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# The Republic
## BOOK II
SOCRATES - GLAUCON
WITH these words I was thinking that I had made an end of the discussion; but the end, in truth, proved to be only a beginning. For Glaucon, who is always the most pugnacious of men, was dissatisfied at Thrasymachus' retirement; he wanted to have the battle out.
So he said to me: Socrates, do you wish really to persuade us, or only to seem to have persuaded us, that to be just is always better than to be unjust?
I should wish really to persuade you, I replied, if I could.
Then you certainly have not succeeded. Let me ask you now:--How would you arrange goods--are there not some which we welcome for their own sakes, and independently of their consequences, as, for example, harmless pleasures and enjoyments, which delight us at the time, although nothing follows from them?
I agree in thinking that there is such a class, I replied.
Is there not also a second class of goods, such as knowledge, sight, health, which are desirable not only in themselves, but also for their results?
Certainly, I said.
And would you not recognize a third class, such as gymnastic, and the care of the sick, and the physician's art; also the various ways of money-making--these do us good but we regard them as disagreeable; and no one would choose them for their own sakes, but only for the sake of some reward or result which flows from them?
There is, I said, this third class also. But why do you ask?
Because I want to know in which of the three classes you would place justice?
In the highest class, I replied,--among those goods which he who would be happy desires both for their own sake and for the sake of their results.
Then the many are of another mind; they think that justice is to be reckoned in the troublesome class, among goods which are to be pursued for the sake of rewards and of reputation, but in themselves are disagreeable and rather to be avoided.
I know, I said, that this is their manner of thinking, and that this was the thesis which Thrasymachus was maintaining just now, when he censured justice and praised injustice. But I am too stupid to be convinced by him.
I wish, he said, that you would hear me as well as him, and then I shall see whether you and I agree. For Thrasymachus seems to me, like a snake, to have been charmed by your voice sooner than he ought to have been; but to my mind the nature of justice and injustice have not yet been made clear. Setting aside their rewards and results, I want to know what they are in themselves, and how they inwardly work in the soul.
If you, please, then, I will revive the argument of Thrasymachus.
And first I will speak of the nature and origin of justice according to the common view of them. Secondly, I will show that all men who practise justice do so against their will, of necessity, but not as a good. And thirdly, I will argue that there is reason in this view, for the life of the unjust is after all better far than the life of the just--if what they say is true, Socrates, since I myself am not of their opinion. But still I acknowledge that I am perplexed when I hear the voices of Thrasymachus and myriads of others dinning in my ears; and, on the other hand, I have never yet heard the superiority of justice to injustice maintained by any one in a satisfactory way. I want to hear justice praised in respect of itself; then I shall be satisfied, and you are the person from whom I think that I am most likely to hear this; and therefore I will praise the unjust life to the utmost of my power, and my manner of speaking will indicate the manner in which I desire to hear you too praising justice and censuring injustice.
Will you say whether you approve of my proposal?
Indeed I do; nor can I imagine any theme about which a man of sense would oftener wish to converse.
I am delighted, he replied, to hear you say so, and shall begin by speaking, as I proposed, of the nature and origin of justice.
GLAUCON
They say that to do injustice is, by nature, good; to suffer injustice, evil; but that the evil is greater than the good.
And so when men have both done and suffered injustice and have had experience of both, not being able to avoid the one and obtain the other, they think that they had better agree among themselves to have neither; hence there arise laws and mutual covenants; and that which is ordained by law is termed by them lawful and just.
This they affirm to be the origin and nature of justice;--it is a mean or compromise, between the best of all, which is to do injustice and not be punished, and the worst of all, which is to suffer injustice without the power of retaliation; and justice, being at a middle point between the two, is tolerated not as a good, but as the lesser evil, and honoured by reason of the inability of men to do injustice.
For no man who is worthy to be called a man would ever submit to such an agreement if he were able to resist; he would be mad if he did.
Such is the received account, Socrates, of the nature and origin of justice.
Now that those who practise justice do so involuntarily and because they have not the power to be unjust will best appear if we imagine something of this kind: having given both to the just and the unjust power to do what they will, let us watch and see whither desire will lead them; then we shall discover in the very act the just and unjust man to be proceeding along the same road, following their interest, which all natures deem to be their good, and are only diverted into the path of justice by the force of law.
The liberty which we are supposing may be most completely given to them in the form of such a power as is said to have been possessed by Gyges the ancestor of Croesus the Lydian.
According to the tradition, Gyges was a shepherd in the service of the king of Lydia; there was a great storm, and an earthquake made an opening in the earth at the place where he was feeding his flock.
Amazed at the sight, he descended into the opening, where, among other marvels, he beheld a hollow brazen horse, having doors, at which he stooping and looking in saw a dead body of stature, as appeared to him, more than human, and having nothing on but a gold ring; this he took from the finger of the dead and reascended.
Now the shepherds met together, according to custom, that they might send their monthly report about the flocks to the king; into their assembly he came having the ring on his finger, and as he was sitting among them he chanced to turn the collet of the ring inside his hand, when instantly he became invisible to the rest of the company and they began to speak of him as if he were no longer present.
He was astonished at this, and again touching the ring he turned the collet outwards and reappeared; he made several trials of the ring, and always with the same result-when he turned the collet inwards he became invisible, when outwards he reappeared. Whereupon he contrived to be chosen one of the messengers who were sent to the court; where as soon as he arrived he seduced the queen, and with her help conspired against the king and slew him, and took the kingdom.
Suppose now that there were two such magic rings, and the just put on one of them and the unjust the other;,no man can be imagined to be of such an iron nature that he would stand fast in justice.
No man would keep his hands off what was not his own when he could safely take what he liked out of the market, or go into houses and lie with any one at his pleasure, or kill or release from prison whom he would, and in all respects be like a God among men.
Then the actions of the just would be as the actions of the unjust; they would both come at last to the same point. And this we may truly affirm to be a great proof that a man is just, not willingly or because he thinks that justice is any good to him individually, but of necessity, for wherever any one thinks that he can safely be unjust, there he is unjust. For all men believe in their hearts that injustice is far more profitable to the individual than justice, and he who argues as I have been supposing, will say that they are right.
If you could imagine any one obtaining this power of becoming invisible, and never doing any wrong or touching what was another's, he would be thought by the lookers-on to be a most wretched idiot, although they would praise him to one another's faces, and keep up appearances with one another from a fear that they too might suffer injustice.
Enough of this.
Now, if we are to form a real judgment of the life of the just and unjust, we must isolate them; there is no other way; and how is the isolation to be effected? I answer: Let the unjust man be entirely unjust, and the just man entirely just; nothing is to be taken away from either of them, and both are to be perfectly furnished for the work of their respective lives. First, let the unjust be like other distinguished masters of craft; like the skilful pilot or physician, who knows intuitively his own powers and keeps within their limits, and who, if he fails at any point, is able to recover himself.
So let the unjust make his unjust attempts in the right way, and lie hidden if he means to be great in his injustice (he who is found out is nobody): for the highest reach of injustice is:
to be deemed just when you are not. Therefore I say that in the perfectly unjust man we must assume the most perfect injustice; there is to be no deduction, but we must allow him, while doing the most unjust acts, to have acquired the greatest reputation for justice.
If he have taken a false step he must be able to recover himself; he must be one who can speak with effect, if any of his deeds come to light, and who can force his way where force is required his courage and strength, and command of money and friends.
And at his side let us place the just man in his nobleness and simplicity, wishing, as Aeschylus says, to be and not to seem good.
There must be no seeming, for if he seem to be just he will be honoured and rewarded, and then we shall not know whether he is just for the sake of justice or for the sake of honours and rewards; therefore, let him be clothed in justice only, and have no other covering; and he must be imagined in a state of life the opposite of the former.
Let him be the best of men, and let him be thought the worst; then he will have been put to the proof; and we shall see whether he will be affected by the fear of infamy and its consequences.
And let him continue thus to the hour of death; being just and seeming to be unjust. When both have reached the uttermost extreme, the one of justice and the other of injustice, let judgment be given which of them is the happier of the two.
SOCRATES - GLAUCON
Heavens! my dear Glaucon, I said, how energetically you polish them up for the decision, first one and then the other, as if they were two statues.
I do my best, he said. And now that we know what they are like there is no difficulty in tracing out the sort of life which awaits either of them. This I will proceed to describe; but as you may think the description a little too coarse, I ask you to suppose, Socrates, that the words which follow are not mine.-- Let me put them into the mouths of the eulogists of injustice:
They will tell you that the just man who is thought unjust will be scourged, racked, bound--will have his eyes burnt out; and, at last, after suffering every kind of evil, he will be impaled: Then he will understand that he ought to seem only, and not to be, just; the words of Aeschylus may be more truly spoken of the unjust than of the just. For the unjust is pursuing a reality; he does not live with a view to appearances--he wants to be really unjust and not to seem only:--
His mind has a soil deep and fertile,
Out of which spring his prudent counsels.
In the first place, he is thought just, and therefore bears rule in the city; he can marry whom he will, and give in marriage to whom he will; also he can trade and deal where he likes, and always to his own advantage, because he has no misgivings about injustice and at every contest, whether in public or private, he gets the better of his antagonists, and gains at their expense, and is rich, and out of his gains he can benefit his friends, and harm his enemies; moreover, he can offer sacrifices, and dedicate gifts to the gods abundantly and magnificently, and can honour the gods or any man whom he wants to honour in a far better style than the just, and therefore he is likely to be dearer than they are to the gods.
And thus, Socrates, gods and men are said to unite in making the life of the unjust better than the life of the just.
I was going to say something in answer to Glaucon, when Adeimantus, his brother, interposed: Socrates, he said, you do not suppose that there is nothing more to be urged?
Why, what else is there? I answered.
The strongest point of all has not been even mentioned, he replied.
Well, then, according to the proverb, Let brother help brother'-- if he fails in any part do you assist him; although I must confess that Glaucon has already said quite enough to lay me in the dust, and take from me the power of helping justice.
Nonsense, he replied. But let me add something more: There is another side to Glaucon's argument about the praise and censure of justice and injustice, which is equally required in order to bring out what I believe to be his meaning. Parents and tutors are always telling their sons and their wards that they are to be just; but why? not for the sake of justice, but for the sake of character and reputation; in the hope of obtaining for him who is reputed just some of those offices, marriages, and the like which Glaucon has enumerated among the advantages accruing to the unjust from the reputation of justice. More, however, is made of appearances by this class of persons than by the others; for they throw in the good opinion of the gods, and will tell you of a shower of benefits which the heavens, as they say, rain upon the pious; and this accords with the testimony of the noble Hesiod and Homer, the first of whom says, that the gods make the oaks of the just--
To hear acorns at their summit, and bees I the middle;
And the sheep the bowed down bowed the with the their fleeces.
and many other blessings of a like kind are provided for them.
And Homer has a very similar strain; for he speaks of one whose fame is--
As the fame of some blameless king who, like a god,
Maintains justice to whom the black earth brings forth
Wheat and barley, whose trees are bowed with fruit,
And his sheep never fail to bear, and the sea gives him fish.
Still grander are the gifts of heaven which Musaeus and his son vouchsafe to the just; they take them down into the world below, where they have the saints lying on couches at a feast, everlastingly drunk, crowned with garlands; their idea seems to be that an immortality of drunkenness is the highest meed of virtue.
Some extend their rewards yet further; the posterity, as they say, of the faithful and just shall survive to the third and fourth generation.
This is the style in which they praise justice. But about the wicked there is another strain; they bury them in a slough in Hades, and make them carry water in a sieve; also while they are yet living they bring them to infamy, and inflict upon them the punishments which Glaucon described as the portion of the just who are reputed to be unjust; nothing else does their invention supply. Such is their manner of praising the one and censuring the other.
Once more, Socrates, I will ask you to consider another way of speaking about justice and injustice, which is not confined to the poets, but is found in prose writers. The universal voice of mankind is always declaring that justice and virtue are honourable, but grievous and toilsome; and that the pleasures of vice and injustice are easy of attainment, and are only censured by law and opinion.
They say also that honesty is for the most part less profitable than dishonesty; and they are quite ready to call wicked men happy, and to honour them both in public and private when they are rich or in any other way influential, while they despise and overlook those who may be weak and poor, even though acknowledging them to be better than the others. But most extraordinary of all is their mode of speaking about virtue and the gods:
they say that the gods apportion calamity and misery to many good men, and good and happiness to the wicked. And mendicant prophets go to rich men's doors and persuade them that they have a power committed to them by the gods of making an atonement for a man's own or his ancestor's sins by sacrifices or charms, with rejoicings and feasts; and they promise to harm an enemy, whether just or unjust, at a small cost; with magic arts and incantations binding heaven, as they say, to execute their will. And the poets are the authorities to whom they appeal, now smoothing the path of vice with the words of Hesiod;--
Vice may be had in abundance without trouble; the way is smooth
and her dwelling-place is near. But before virtue the gods have
set toil,
and a tedious and uphill road: then citing Homer as a witness that the gods may be influenced by men; for he also says:
The gods, too, may he turned from their purpose; and men pray to
them and avert their wrath by sacrifices and soothing entreaties,
and by libations and the odour of fat, when they have sinned and
transgressed.
And they produce a host of books written by Musaeus and Orpheus, who were children of the Moon and the Muses--that is what they say-- according to which they perform their ritual, and persuade not only individuals, but whole cities, that expiations and atonements for sin may be made by sacrifices and amusements which fill a vacant hour, and are equally at the service of the living and the dead; the latter sort they call mysteries, and they redeem us from the pains of hell, but if we neglect them no one knows what awaits us.
He proceeded: And now when the young hear all this said about virtue and vice, and the way in which gods and men regard them, how are their minds likely to be affected, my dear Socrates,-- those of them, I mean, who are quickwitted, and, like bees on the wing, light on every flower, and from all that they hear are prone to draw conclusions as to what manner of persons they should be and in what way they should walk if they would make the best of life?
Probably the youth will say to himself in the words of Pindar--
Can I by justice or by crooked ways of deceit ascend a loftier
tower which may he a fortress to me all my days?
For what men say is that, if I am really just and am not also thought just profit there is none, but the pain and loss on the other hand are unmistakable. But if, though unjust, I acquire the reputation of justice, a heavenly life is promised to me. Since then, as philosophers prove, appearance tyrannizes over truth and is lord of happiness, to appearance I must devote myself. I will describe around me a picture and shadow of virtue to be the vestibule and exterior of my house; behind I will trail the subtle and crafty fox, as Archilochus, greatest of sages, recommends. But I hear some one exclaiming that the concealment of wickedness is often difficult; to which I answer, Nothing great is easy. Nevertheless, the argument indicates this, if we would be happy, to be the path along which we should proceed. With a view to concealment we will establish secret brotherhoods and political clubs. And there are professors of rhetoric who teach the art of persuading courts and assemblies; and so, partly by persuasion and partly by force, I shall make unlawful gains and not be punished. Still I hear a voice saying that the gods cannot be deceived, neither can they be compelled.
But what if there are no gods? or, suppose them to have no care of human things--why in either case should we mind about concealment?
And even if there are gods, and they do care about us, yet we know of them only from tradition and the genealogies of the poets; and these are the very persons who say that they may be influenced and turned by sacrifices and soothing entreaties and by offerings.'
Let us be consistent then, and believe both or neither.
If the poets speak truly, why then we had better be unjust, and offer of the fruits of injustice; for if we are just, although we may escape the vengeance of heaven, we shall lose the gains of injustice; but, if we are unjust, we shall keep the gains, and by our sinning and praying, and praying and sinning, the gods will be propitiated, and we shall not be punished.
But there is a world below in which either we or our posterity will suffer for our unjust deeds.' Yes, my friend, will be the reflection, but there are mysteries and atoning deities, and these have great power. That is what mighty cities declare; and the children of the gods, who were their poets and prophets, bear a like testimony.
On what principle, then, shall we any longer choose justice rather than the worst injustice? when, if we only unite the latter with a deceitful regard to appearances, we shall fare to our mind both with gods and men, in life and after death, as the most numerous and the highest authorities tell us.
Knowing all this, Socrates, how can a man who has any superiority of mind or person or rank or wealth, be willing to honour justice; or indeed to refrain from laughing when he hears justice praised?
And even if there should be some one who is able to disprove the truth of my words, and who is satisfied that justice is best, still he is not angry with the unjust, but is very ready to forgive them, because he also knows that men are not just of their own free will; unless, peradventure, there be some one whom the divinity within him may have inspired with a hatred of injustice, or who has attained knowledge of the truth--but no other man.
He only blames injustice who, owing to cowardice or age or some weakness, has not the power of being unjust. And this is proved by the fact that when he obtains the power, he immediately becomes unjust as far as he can be.
The cause of all this, Socrates, was indicated by us at the beginning of the argument, when my brother and I told you how astonished we were to find that of all the professing panegyrists of justice-- beginning with the ancient heroes of whom any memorial has been preserved to us, and ending with the men of our own time-- no one has ever blamed injustice or praised justice except with a view to the glories, honours, and benefits which flow from them.
No one has ever adequately described either in verse or prose the true essential nature of either of them abiding in the soul, and invisible to any human or divine eye; or shown that of all the things of a man's soul which he has within him, justice is the greatest good, and injustice the greatest evil.
Had this been the universal strain, had you sought to persuade us of this from our youth upwards, we should not have been on the watch to keep one another from doing wrong, but every one would have been his own watchman, because afraid, if he did wrong, of harbouring in himself the greatest of evils. I dare say that Thrasymachus and others would seriously hold the language which I have been merely repeating, and words even stronger than these about justice and injustice, grossly, as I conceive, perverting their true nature.
But I speak in this vehement manner, as I must frankly confess to you, because I want to hear from you the opposite side; and I would ask you to show not only the superiority which justice has over injustice, but what effect they have on the possessor of them which makes the one to be a good and the other an evil to him. And please, as Glaucon requested of you, to exclude reputations; for unless you take away from each of them his true reputation and add on the false, we shall say that you do not praise justice, but the appearance of it; we shall think that you are only exhorting us to keep injustice dark, and that you really agree with Thrasymachus in thinking that justice is another's good and the interest of the stronger, and that injustice is a man's own profit and interest, though injurious to the weaker.
Now as you have admitted that justice is one of that highest class of goods which are desired indeed for their results, but in a far greater degree for their own sakes--like sight or hearing or knowledge or health, or any other real and natural and not merely conventional good-- I would ask you in your praise of justice to regard one point only:
I mean the essential good and evil which justice and injustice work in the possessors of them. Let others praise justice and censure injustice, magnifying the rewards and honours of the one and abusing the other; that is a manner of arguing which, coming from them, I am ready to tolerate, but from you who have spent your whole life in the consideration of this question, unless I hear the contrary from your own lips, I expect something better. And therefore, I say, not only prove to us that justice is better than injustice, but show what they either of them do to the possessor of them, which makes the one to be a good and the other an evil, whether seen or unseen by gods and men.
I had always admired the genius of Glaucon and Adeimantus, but on hearing these words I was quite delighted, and said:
Sons of an illustrious father, that was not a bad beginning of the Elegiac verses which the admirer of Glaucon made in honour of you after you had distinguished yourselves at the battle of Megara:--
Sons of Ariston,' he sang, divine offspring of an
illustrious hero.'
The epithet is very appropriate, for there is something truly divine in being able to argue as you have done for the superiority of injustice, and remaining unconvinced by your own arguments.
And I do believe that you are not convinced--this I infer from your general character, for had I judged only from your speeches I should have mistrusted you. But now, the greater my confidence in you, the greater is my difficulty in knowing what to say. For I am in a strait between two; on the one hand I feel that I am unequal to the task; and my inability is brought home to me by the fact that you were not satisfied with the answer which I made to Thrasymachus, proving, as I thought, the superiority which justice has over injustice.
And yet I cannot refuse to help, while breath and speech remain to me; I am afraid that there would be an impiety in being present when justice is evil spoken of and not lifting up a hand in her defence.
And therefore I had best give such help as I can.
Glaucon and the rest entreated me by all means not to let the question drop, but to proceed in the investigation. They wanted to arrive at the truth, first, about the nature of justice and injustice, and secondly, about their relative advantages. I told them, what I-- really thought, that the enquiry would be of a serious nature, and would require very good eyes. Seeing then, I said, that we are no great wits, I think that we had better adopt a method which I may illustrate thus; suppose that a short-sighted person had been asked by some one to read small letters from a distance; and it occurred to some one else that they might be found in another place which was larger and in which the letters were larger-- if they were the same and he could read the larger letters first, and then proceed to the lesser--this would have been thought a rare piece of good fortune.
Very true, said Adeimantus; but how does the illustration apply to our enquiry?
I will tell you, I replied; justice, which is the subject of our enquiry, is, as you know, sometimes spoken of as the virtue of an individual, and sometimes as the virtue of a State.
True, he replied.
And is not a State larger than an individual?
It is.
Then in the larger the quantity of justice is likely to be larger and more easily discernible. I propose therefore that we enquire into the nature of justice and injustice, first as they appear in the State, and secondly in the individual, proceeding from the greater to the lesser and comparing them.
That, he said, is an excellent proposal.
And if we imagine the State in process of creation, we shall see the justice and injustice of the State in process of creation also.
I dare say.
When the State is completed there may be a hope that the object of our search will be more easily discovered.
Yes, far more easily.
But ought we to attempt to construct one? I said; for to do so, as I am inclined to think, will be a very serious task.
Reflect therefore.
I have reflected, said Adeimantus, and am anxious that you should proceed.
A State, I said, arises, as I conceive, out of the needs of mankind; no one is self-sufficing, but all of us have many wants. Can any other origin of a State be imagined?
There can I be no other.
Then, as we have many wants, and many persons are needed to supply them, one takes a helper for one purpose and another for another; and when these partners and helpers are gathered together in one habitation the body of inhabitants is termed a State.
True, he said.
And they exchange with one another, and one gives, and another receives, under the idea that the exchange will be for their good.
Very true.
Then, I said, let us begin and create in idea a State; and yet the true creator is necessity, who is the mother of our invention.
Of course, he replied.
Now the first and greatest of necessities is food, which is the condition of life and existence.
Certainly.
The second is a dwelling, and the third clothing and the like.
True.
And now let us see how our city will be able to supply this great demand:
We may suppose that one man is a husbandman, another a builder, some one else a weaver--shall we add to them a shoemaker, or perhaps some other purveyor to our bodily wants?
Quite right.
The barest notion of a State must include four or five men.
Clearly.
And how will they proceed? Will each bring the result of his labours into a common stock?--the individual husbandman, for example, producing for four, and labouring four times as long and as much as he need in the provision of food with which he supplies others as well as himself; or will he have nothing to do with others and not be at the trouble of producing for them, but provide for himself alone a fourth of the food in a fourth of the time, and in the remaining three-fourths of his time be employed in making a house or a coat or a pair of shoes, having no partnership with others, but supplying himself all his own wants?
Adeimantus thought that he should aim at producing food only and not at producing everything.
Probably, I replied, that would be the better way; and when I hear you say this, I am myself reminded that we are not all alike; there are diversities of natures among us which are adapted to different occupations.
Very true.
And will you have a work better done when the workman has many occupations, or when he has only one?
When he has only one.
Further, there can be no doubt that a work is spoilt when not done at the right time?
No doubt.
For business is not disposed to wait until the doer of the business is at leisure; but the doer must follow up what he is doing, and make the business his first object.
He must.
And if so, we must infer that all things are produced more plentifully and easily and of a better quality when one man does one thing which is natural to him and does it at the right time, and leaves other things.
Undoubtedly..
Then more than four citizens will be required; for the husbandman will not make his own plough or mattock, or other implements of agriculture, if they are to be good for anything.
Neither will the builder make his tools--and he too needs many; and in like manner the weaver and shoemaker.
True.
Then carpenters, and smiths, and many other artisans, will be sharers in our little State, which is already beginning to grow?
True.
Yet even if we add neatherds, shepherds, and other herdsmen, in order that our husbandmen may have oxen to plough with, and builders as well as husbandmen may have draught cattle, and curriers and weavers fleeces and hides,--still our State will not be very large.
That is true; yet neither will it be a very small State which contains all these.
Then, again, there is the situation of the city--to find a place where nothing need be imported is well-nigh impossible.
Impossible.
Then there must be another class of citizens who will bring the required supply from another city?
There must.
But if the trader goes empty-handed, having nothing which they require who would supply his need, he will come back empty-handed.
That is certain.
And therefore what they produce at home must be not only enough for themselves, but such both in quantity and quality as to accommodate those from whom their wants are supplied.
Very true.
Then more husbandmen and more artisans will be required?
They will.
Not to mention the importers and exporters, who are called merchants?
Yes.
Then we shall want merchants?
We shall.
And if merchandise is to be carried over the sea, skilful sailors will also be needed, and in considerable numbers?
Yes, in considerable numbers.
Then, again, within the city, how will they exchange their productions?
To secure such an exchange was, as you will remember, one of our principal objects when we formed them into a society and constituted a State.
Clearly they will buy and sell.
Then they will need a market-place, and a money-token for purposes of exchange.
Certainly.
Suppose now that a husbandman, or an artisan, brings some production to market, and he comes at a time when there is no one to exchange with him,--is he to leave his calling and sit idle in the market-place?
Not at all; he will find people there who, seeing the want, undertake the office of salesmen. In well-ordered States they are commonly those who are the weakest in bodily strength, and therefore of little use for any other purpose; their duty is to be in the market, and to give money in exchange for goods to those who desire to sell and to take money from those who desire to buy.
This want, then, creates a class of retail-traders in our State.
Is not retailer' the term which is applied to those who sit in the market-place engaged in buying and selling, while those who wander from one city to another are called merchants?
Yes, he said.
And there is another class of servants, who are intellectually hardly on the level of companionship; still they have plenty of bodily strength for labour, which accordingly they sell, and are called, if I do not mistake, hirelings, hire being the name which is given to the price of their labour.
True.
Then hirelings will help to make up our population?
Yes.
And now, Adeimantus, is our State matured and perfected?
I think so.
Where, then, is justice, and where is injustice, and in what part of the State did they spring up?
Probably in the dealings of these citizens with one another.
cannot imagine that they are more likely to be found anywhere else.
I dare say that you are right in your suggestion, I said; we had better think the matter out, and not shrink from the enquiry.
Let us then consider, first of all, what will be their way of life, now that we have thus established them. Will they not produce corn, and wine, and clothes, and shoes, and build houses for themselves?
And when they are housed, they will work, in summer, commonly, stripped and barefoot, but in winter substantially clothed and shod. They will feed on barley-meal and flour of wheat, baking and kneading them, making noble cakes and loaves; these they will serve up on a mat of reeds or on clean leaves, themselves reclining the while upon beds strewn with yew or myrtle.
And they and their children will feast, drinking of the wine which they have made, wearing garlands on their heads, and hymning the praises of the gods, in happy converse with one another.
And they will take care that their families do not exceed their means; having an eye to poverty or war.
SOCRATES - GLAUCON
But, said Glaucon, interposing, you have not given them a relish to their meal.
True, I replied, I had forgotten; of course they must have a relish-salt, and olives, and cheese, and they will boil roots and herbs such as country people prepare; for a dessert we shall give them figs, and peas, and beans; and they will roast myrtle-berries and acorns at the fire, drinking in moderation. And with such a diet they may be expected to live in peace and health to a good old age, and bequeath a similar life to their children after them.
Yes, Socrates, he said, and if you were providing for a city of pigs, how else would you feed the beasts?
But what would you have, Glaucon? I replied.
Why, he said, you should give them the ordinary conveniences of life.
People who are to be comfortable are accustomed to lie on sofas, and dine off tables, and they should have sauces and sweets in the modern style.
Yes, I said, now I understand: the question which you would have me consider is, not only how a State, but how a luxurious State is created; and possibly there is no harm in this, for in such a State we shall be more likely to see how justice and injustice originate.
In my opinion the true and healthy constitution of the State is the one which I have described. But if you wish also to see a State at fever heat, I have no objection. For I suspect that many will not be satisfied with the simpler way of way They will be for adding sofas, and tables, and other furniture; also dainties, and perfumes, and incense, and courtesans, and cakes, all these not of one sort only, but in every variety; we must go beyond the necessaries of which I was at first speaking, such as houses, and clothes, and shoes:
the arts of the painter and the embroiderer will have to be set in motion, and gold and ivory and all sorts of materials must be procured.
True, he said.
Then we must enlarge our borders; for the original healthy State is no longer sufficient. Now will the city have to fill and swell with a multitude of callings which are not required by any natural want; such as the whole tribe of hunters and actors, of whom one large class have to do with forms and colours; another will be the votaries of music--poets and their attendant train of rhapsodists, players, dancers, contractors; also makers of divers kinds of articles, including women's dresses. And we shall want more servants. Will not tutors be also in request, and nurses wet and dry, tirewomen and barbers, as well as confectioners and cooks; and swineherds, too, who were not needed and therefore had no place in the former edition of our State, but are needed now? They must not be forgotten: and there will be animals of many other kinds, if people eat them.
Certainly.
And living in this way we shall have much greater need of physicians than before?
Much greater.
And the country which was enough to support the original inhabitants will be too small now, and not enough?
Quite true.
Then a slice of our neighbours' land will be wanted by us for pasture and tillage, and they will want a slice of ours, if, like ourselves, they exceed the limit of necessity, and give themselves up to the unlimited accumulation of wealth?
That, Socrates, will be inevitable.
And so we shall go to war, Glaucon. Shall we not?
Most certainly, he replied.
Then without determining as yet whether war does good or harm, thus much we may affirm, that now we have discovered war to be derived from causes which are also the causes of almost all the evils in States, private as well as public.
Undoubtedly.
And our State must once more enlarge; and this time the will be nothing short of a whole army, which will have to go out and fight with the invaders for all that we have, as well as for the things and persons whom we were describing above.
Why? he said; are they not capable of defending themselves?
No, I said; not if we were right in the principle which was acknowledged by all of us when we were framing the State:
the principle, as you will remember, was that one man cannot practise many arts with success.
Very true, he said.
But is not war an art?
Certainly.
And an art requiring as much attention as shoemaking?
Quite true.
And the shoemaker was not allowed by us to be husbandman, or a weaver, a builder--in order that we might have our shoes well made; but to him and to every other worker was assigned one work for which he was by nature fitted, and at that he was to continue working all his life long and at no other; he was not to let opportunities slip, and then he would become a good workman.
Now nothing can be more important than that the work of a soldier should be well done. But is war an art so easily acquired that a man may be a warrior who is also a husbandman, or shoemaker, or other artisan; although no one in the world would be a good dice or draught player who merely took up the game as a recreation, and had not from his earliest years devoted himself to this and nothing else?
No tools will make a man a skilled workman, or master of defence, nor be of any use to him who has not learned how to handle them, and has never bestowed any attention upon them. How then will he who takes up a shield or other implement of war become a good fighter all in a day, whether with heavy-armed or any other kind of troops?
Yes, he said, the tools which would teach men their own use would be beyond price.
And the higher the duties of the guardian, I said, the more time, and skill, and art, and application will be needed by him?
No doubt, he replied.
Will he not also require natural aptitude for his calling?
Certainly.
Then it will be our duty to select, if we can, natures which are fitted for the task of guarding the city?
It will.
And the selection will be no easy matter, I said; but we must be brave and do our best.
We must.
Is not the noble youth very like a well-bred dog in respect of guarding and watching?
What do you mean?
I mean that both of them ought to be quick to see, and swift to overtake the enemy when they see him; and strong too if, when they have caught him, they have to fight with him.
All these qualities, he replied, will certainly be required by them.
Well, and your guardian must be brave if he is to fight well?
Certainly.
And is he likely to be brave who has no spirit, whether horse or dog or any other animal? Have you never observed how invincible and unconquerable is spirit and how the presence of it makes the soul of any creature to be absolutely fearless and indomitable?
I have.
Then now we have a clear notion of the bodily qualities which are required in the guardian.
True.
And also of the mental ones; his soul is to be full of spirit?
Yes.
But are not these spirited natures apt to be savage with one another, and with everybody else?
A difficulty by no means easy to overcome, he replied.
Whereas, I said, they ought to be dangerous to their enemies, and gentle to their friends; if not, they will destroy themselves without waiting for their enemies to destroy them.
True, he said.
What is to be done then? I said; how shall we find a gentle nature which has also a great spirit, for the one is the contradiction of the other?
True.
He will not be a good guardian who is wanting in either of these two qualities; and yet the combination of them appears to be impossible; and hence we must infer that to be a good guardian is impossible.
I am afraid that what you say is true, he replied.
Here feeling perplexed I began to think over what had preceded.
My friend, I said, no wonder that we are in a perplexity; for we have lost sight of the image which we had before us.
What do you mean? he said.
I mean to say that there do exist natures gifted with those opposite qualities.
And where do you find them?
Many animals, I replied, furnish examples of them; our friend the dog is a very good one: you know that well-bred dogs are perfectly gentle to their familiars and acquaintances, and the reverse to strangers.
Yes, I know.
Then there is nothing impossible or out of the order of nature in our finding a guardian who has a similar combination of qualities?
Certainly not.
Would not he who is fitted to be a guardian, besides the spirited nature, need to have the qualities of a philosopher?
I do not apprehend your meaning.
The trait of which I am speaking, I replied, may be also seen in the dog, and is remarkable in the animal.
What trait?
Why, a dog, whenever he sees a stranger, is angry; when an acquaintance, he welcomes him, although the one has never done him any harm, nor the other any good. Did this never strike you as curious?
The matter never struck me before; but I quite recognise the truth of your remark.
And surely this instinct of the dog is very charming;--your dog is a true philosopher.
Why?
Why, because he distinguishes the face of a friend and of an enemy only by the criterion of knowing and not knowing.
And must not an animal be a lover of learning who determines what he likes and dislikes by the test of knowledge and ignorance?
Most assuredly.
And is not the love of learning the love of wisdom, which is philosophy?
They are the same, he replied.
And may we not say confidently of man also, that he who is likely to be gentle to his friends and acquaintances, must by nature be a lover of wisdom and knowledge?
That we may safely affirm.
Then he who is to be a really good and noble guardian of the State will require to unite in himself philosophy and spirit and swiftness and strength?
Undoubtedly.
Then we have found the desired natures; and now that we have found them, how are they to be reared and educated?
Is not this enquiry which may be expected to throw light on the greater enquiry which is our final end--How do justice and injustice grow up in States? for we do not want either to omit what is to the point or to draw out the argument to an inconvenient length.
Adeimantus thought that the enquiry would be of great service to us.
Then, I said, my dear friend, the task must not be given up, even if somewhat long.
Certainly not.
Come then, and let us pass a leisure hour in story-telling, and our story shall be the education of our heroes.
By all means.
And what shall be their education? Can we find a better than the traditional sort?--and this has two divisions, gymnastic for the body, and music for the soul.
True.
Shall we begin education with music, and go on to gymnastic afterwards?
By all means.
And when you speak of music, do you include literature or not?
I do.
And literature may be either true or false?
Yes.
And the young should be trained in both kinds, and we begin with the false?
I do not understand your meaning, he said.
You know, I said, that we begin by telling children stories which, though not wholly destitute of truth, are in the main fictitious; and these stories are told them when they are not of an age to learn gymnastics.
Very true.
That was my meaning when I said that we must teach music before gymnastics.
Quite right, he said.
You know also that the beginning is the most important part of any work, especially in the case of a young and tender thing; for that is the time at which the character is being formed and the desired impression is more readily taken.
Quite true.
And shall we just carelessly allow children to hear any casual tales which may be devised by casual persons, and to receive into their minds ideas for the most part the very opposite of those which we should wish them to have when they are grown up?
We cannot.
Then the first thing will be to establish a censorship of the writers of fiction, and let the censors receive any tale of fiction which is good, and reject the bad; and we will desire mothers and nurses to tell their children the authorised ones only. Let them fashion the mind with such tales, even more fondly than they mould the body with their hands; but most of those which are now in use must be discarded.
Of what tales are you speaking? he said.
You may find a model of the lesser in the greater, I said; for they are necessarily of the same type, and there is the same spirit in both of them.
Very likely, he replied; but I do not as yet know what you would term the greater.
Those, I said, which are narrated by Homer and Hesiod, and the rest of the poets, who have ever been the great story-tellers of mankind.
But which stories do you mean, he said; and what fault do you find with them?
A fault which is most serious, I said; the fault of telling a lie, and, what is more, a bad lie.
But when is this fault committed?
Whenever an erroneous representation is made of the nature of gods and heroes,--as when a painter paints a portrait not having the shadow of a likeness to the original.
Yes, he said, that sort of thing is certainly very blamable; but what are the stories which you mean?
First of all, I said, there was that greatest of all lies, in high places, which the poet told about Uranus, and which was a bad lie too,-- I mean what Hesiod says that Uranus did, and how Cronus retaliated on him. The doings of Cronus, and the sufferings which in turn his son inflicted upon him, even if they were true, ought certainly not to be lightly told to young and thoughtless persons; if possible, they had better be buried in silence. But if there is an absolute necessity for their mention, a chosen few might hear them in a mystery, and they should sacrifice not a common [Eleusinian] pig, but some huge and unprocurable victim; and then the number of the hearers will be very few indeed.
Why, yes, said he, those stories are extremely objectionable.
Yes, Adeimantus, they are stories not to be repeated in our State; the young man should not be told that in committing the worst of crimes he is far from doing anything outrageous; and that even if he chastises his father when does wrong, in whatever manner, he will only be following the example of the first and greatest among the gods.
I entirely agree with you, he said; in my opinion those stories are quite unfit to be repeated.
Neither, if we mean our future guardians to regard the habit of quarrelling among themselves as of all things the basest, should any word be said to them of the wars in heaven, and of the plots and fightings of the gods against one another, for they are not true. No, we shall never mention the battles of the giants, or let them be embroidered on garments; and we shall be silent about the innumerable other quarrels of gods and heroes with their friends and relatives. If they would only believe us we would tell them that quarrelling is unholy, and that never up to this time has there been any, quarrel between citizens; this is what old men and old women should begin by telling children; and when they grow up, the poets also should be told to compose for them in a similar spirit. But the narrative of Hephaestus binding Here his mother, or how on another occasion Zeus sent him flying for taking her part when she was being beaten, and all the battles of the gods in Homer--these tales must not be admitted into our State, whether they are supposed to have an allegorical meaning or not.
For a young person cannot judge what is allegorical and what is literal; anything that he receives into his mind at that age is likely to become indelible and unalterable; and therefore it is most important that the tales which the young first hear should be models of virtuous thoughts.
There you are right, he replied; but if any one asks where are such models to be found and of what tales are you speaking-- how shall we answer him?
I said to him, You and I, Adeimantus, at this moment are not poets, but founders of a State: now the founders of a State ought to know the general forms in which poets should cast their tales, and the limits which must be observed by them, but to make the tales is not their business.
Very true, he said; but what are these forms of theology which you mean?
Something of this kind, I replied:--God is always to be represented as he truly is, whatever be the sort of poetry, epic, lyric or tragic, in which the representation is given.
Right.
And is he not truly good? and must he not be represented as such?
Certainly.
And no good thing is hurtful?
No, indeed.
And that which is not hurtful hurts not?
Certainly not.
And that which hurts not does no evil?
No.
And can that which does no evil be a cause of evil?
Impossible.
Yes.
And therefore the cause of well-being?
Yes.
It follows therefore that the good is not the cause of all things, but of the good only?
Assuredly.
Then God, if he be good, is not the author of all things, as the many assert, but he is the cause of a few things only, and not of most things that occur to men. For few are the goods of human life, and many are the evils, and the good is to be attributed to God alone; of the evils the causes are to be sought elsewhere, and not in him.
That appears to me to be most true, he said.
Then we must not listen to Homer or to any other poet who is guilty of the folly of saying that two casks
Lie at the threshold of Zeus, full of lots, one of good,
the other of evil lots,
and that he to whom Zeus gives a mixture of the two
Sometimes meets with evil fortune, at other times with good;
but that he to whom is given the cup of unmingled ill,
Him wild hunger drives o'er the beauteous earth.
And again
Zeus, who is the dispenser of good and evil to us.
And if any one asserts that the violation of oaths and treaties, which was really the work of Pandarus, was brought about by Athene and Zeus, or that the strife and contention of the gods was instigated by Themis and Zeus, he shall not have our approval; neither will we allow our young men to hear the words of Aeschylus, that
God plants guilt among men when he desires utterly to
destroy a house.
And if a poet writes of the sufferings of Niobe--the subject of the tragedy in which these iambic verses occur--or of the house of Pelops, or of the Trojan war or on any similar theme, either we must not permit him to say that these are the works of God, or if they are of God, he must devise some explanation of them such as we are seeking; he must say that God did what was just and right, and they were the better for being punished; but that those who are punished are miserable, and that God is the author of their misery-- the poet is not to be permitted to say; though he may say that the wicked are miserable because they require to be punished, and are benefited by receiving punishment from God; but that God being good is the author of evil to any one is to be strenuously denied, and not to be said or sung or heard in verse or prose by any one whether old or young in any well-ordered commonwealth.
Such a fiction is suicidal, ruinous, impious.
I agree with you, he replied, and am ready to give my assent to the law.
Let this then be one of our rules and principles concerning the gods, to which our poets and reciters will be expected to conform-- that God is not the author of all things, but of good only.
That will do, he said.
And what do you think of a second principle? Shall I ask you whether God is a magician, and of a nature to appear insidiously now in one shape, and now in another--sometimes himself changing and passing into many forms, sometimes deceiving us with the semblance of such transformations; or is he one and the same immutably fixed in his own proper image?
I cannot answer you, he said, without more thought.
Well, I said; but if we suppose a change in anything, that change must be effected either by the thing itself, or by some other thing?
Most certainly.
And things which are at their best are also least liable to be altered or discomposed; for example, when healthiest and strongest, the human frame is least liable to be affected by meats and drinks, and the plant which is in the fullest vigour also suffers least from winds or the heat of the sun or any similar causes.
Of course.
And will not the bravest and wisest soul be least confused or deranged by any external influence?
True.
And the same principle, as I should suppose, applies to all composite things--furniture, houses, garments; when good and well made, they are least altered by time and circumstances.
Very true.
Then everything which is good, whether made by art or nature, or both, is least liable to suffer change from without?
True.
But surely God and the things of God are in every way perfect?
Of course they are.
Then he can hardly be compelled by external influence to take many shapes?
He cannot.
But may he not change and transform himself?
Clearly, he said, that must be the case if he is changed at all.
And will he then change himself for the better and fairer, or for the worse and more unsightly?
If he change at all he can only change for the worse, for we cannot suppose him to be deficient either in virtue or beauty.
Very true, Adeimantus; but then, would any one, whether God or man, desire to make himself worse?
Impossible.
Then it is impossible that God should ever be willing to change; being, as is supposed, the fairest and best that is conceivable, every god remains absolutely and for ever in his own form.
That necessarily follows, he said, in my judgment.
Then, I said, my dear friend, let none of the poets tell us that
The gods, taking the disguise of strangers from other lands,
walk up and down cities in all sorts of forms;
and let no one slander Proteus and Thetis, neither let any one, either in tragedy or in any other kind of poetry, introduce Here disguised in the likeness of a priestess asking an alms
For the life-giving daughters of Inachus the river of Argos;
--let us have no more lies of that sort. Neither must we have mothers under the influence of the poets scaring their children with a bad version of these myths--telling how certain gods, as they say, `Go about by night in the likeness of so many strangers and in divers forms'; but let them take heed lest they make cowards of their children, and at the same time speak blasphemy against the gods.
Heaven forbid, he said.
But although the gods are themselves unchangeable, still by witchcraft and deception they may make us think that they appear in various forms?
Perhaps, he replied.
Well, but can you imagine that God will be willing to lie, whether in word or deed, or to put forth a phantom of himself?
I cannot say, he replied.
Do you not know, I said, that the true lie, if such an expression may be allowed, is hated of gods and men?
What do you mean? he said.
I mean that no one is willingly deceived in that which is the truest and highest part of himself, or about the truest and highest matters; there, above all, he is most afraid of a lie having possession of him.
Still, he said, I do not comprehend you.
The reason is, I replied, that you attribute some profound meaning to my words; but I am only saying that deception, or being deceived or uninformed about the highest realities in the highest part of themselves, which is the soul, and in that part of them to have and to hold the lie, is what mankind least like;--that, I say, is what they utterly detest.
There is nothing more hateful to them.
And, as I was just now remarking, this ignorance in the soul of him who is deceived may be called the true lie; for the lie in words is only a kind of imitation and shadowy image of a previous affection of the soul, not pure unadulterated falsehood. Am I not right?
Perfectly right.
The true lie is hated not only by the gods, but also by men?
Yes.
Whereas the lie in words is in certain cases useful and not hateful; in dealing with enemies--that would be an instance; or again, when those whom we call our friends in a fit of madness or illusion are going to do some harm, then it is useful and is a sort of medicine or preventive; also in the tales of mythology, of which we were just now speaking--because we do not know the truth about ancient times, we make falsehood as much like truth as we can, and so turn it to account.
Very true, he said.
But can any of these reasons apply to God? Can we suppose that he is ignorant of antiquity, and therefore has recourse to invention?
That would be ridiculous, he said.
Then the lying poet has no place in our idea of God?
I should say not.
Or perhaps he may tell a lie because he is afraid of enemies?
That is inconceivable.
But he may have friends who are senseless or mad?
But no mad or senseless person can be a friend of God.
Then no motive can be imagined why God should lie?
None whatever.
Then the superhuman and divine is absolutely incapable of falsehood?
Yes.
Then is God perfectly simple and true both in word and deed; he changes not; he deceives not, either by sign or word, by dream or waking vision.
Your thoughts, he said, are the reflection of my own.
You agree with me then, I said, that this is the second type or form in which we should write and speak about divine things.
The gods are not magicians who transform themselves, neither do they deceive mankind in any way.
I grant that.
Then, although we are admirers of Homer, we do not admire the lying dream which Zeus sends to Agamemnon; neither will we praise the verses of Aeschylus in which Thetis says that Apollo at her nuptials
Was celebrating in song her fair progeny whose days were
to he long, and to know no sickness. And when he had
spoken of my lot as in all things blessed of heaven he
raised a note of triumph and cheered my soul. And I
thought that the word of Phoebus being divine and full
of prophecy, would not fail. And now he himself who
uttered the strain, he who was present at the banquet,
and who said this--he it is who has slain my son.
These are the kind of sentiments about the gods which will arouse our anger; and he who utters them shall be refused a chorus; neither shall we allow teachers to make use of them in the instruction of the young, meaning, as we do, that our guardians, as far as men can be, should be true worshippers of the gods and like them.
I entirely agree, be said, in these principles, and promise to make them my laws.
|
# Rave.mp3 Win98 driver problem
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Last response: in Windows 95/98/ME
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April 23, 2005 9:13:04 AM
I have run the CD and installed win98se driver.
But I can't get my pc to run the Rave.mp 256. I have tried everything I can
think of. This USB port works fine, I use it for my Flash drives without a
problem.The rave says " USB connected " it just won't boot-up at all in win
explorer.
Is there someone out there that may of had the problem?
Is there a way to force the driver install?
Thanks
acer
Anonymous
April 23, 2005 11:19:18 AM
Are we supposed to know what a "Rave.mp 256" is? From your description, I am
guessing it is some sort of USB device....perhaps an mp3 player of some sort??
What won't "boot up"? The computer "boots"....a USB device is "detected". Do you
mean the USB device is not being detected in My Computer?
--
Glen Ventura, MS MVP Shell/User, A+
http://dts-l.org/goodpost.htm
http://www.microsoft.com/communities/conduct/default.ms...
> I have run the CD and installed win98se driver.
> But I can't get my pc to run the Rave.mp 256. I have tried everything I can
> think of. This USB port works fine, I use it for my Flash drives without a
> problem.The rave says " USB connected " it just won't boot-up at all in win
> explorer.
> Is there someone out there that may of had the problem?
> Is there a way to force the driver install?
>
> Thanks
> acer
>
>
April 24, 2005 1:01:32 AM
Thank you.
Yes, it is a mp3 player and yes it is a USB device that is not being
detected.
I installed the driver for Win98se from the CD that came with the player.
But when I plug it in to the USB port, the new hardware wizard pops up.
I send it to the install CD/ driver file. Then it says it can't find
software for this device.
I can use it on a PC with XP without a problem.
Thanks again
Lewis
"glee" <[email protected]> wrote in message
news:eLScoY\[email protected]...
> Are we supposed to know what a "Rave.mp 256" is? From your description, I
am
> guessing it is some sort of USB device....perhaps an mp3 player of some
sort??
>
> What won't "boot up"? The computer "boots"....a USB device is "detected".
Do you
> mean the USB device is not being detected in My Computer?
>
> --
> Glen Ventura, MS MVP Shell/User, A+
> http://dts-l.org/goodpost.htm
> http://www.microsoft.com/communities/conduct/default.ms...
>
>
> "Lewis" <[email protected]> wrote in message
> > I have run the CD and installed win98se driver.
> > But I can't get my pc to run the Rave.mp 256. I have tried everything I
can
> > think of. This USB port works fine, I use it for my Flash drives without
a
> > problem.The rave says " USB connected " it just won't boot-up at all in
win
> > explorer.
> > Is there someone out there that may of had the problem?
> > Is there a way to force the driver install?
> >
> > Thanks
> > acer
> >
> >
>
Related resources
Anonymous
April 24, 2005 1:01:33 AM
Right click on "My Computer" then left click on "Properties".
Click on the "Device Manager" tab, then double-click the "Disk drives" category to
expand it.
Look for your mp3 player model number in the list and double-click it (It will not
be one of the GENERIC drives).
Click on the "Settings" tab, click to put a check in the box for "Removable", click
"OK", then "Close", and reboot.
Note: It may be listed under another category than "Disk Drives", so if not there,
check other categories.
--
Glen Ventura, MS MVP Shell/User, A+
http://dts-l.org/goodpost.htm
http://www.microsoft.com/communities/conduct/default.ms...
> Thank you.
>
> Yes, it is a mp3 player and yes it is a USB device that is not being
> detected.
> I installed the driver for Win98se from the CD that came with the player.
> But when I plug it in to the USB port, the new hardware wizard pops up.
> I send it to the install CD/ driver file. Then it says it can't find
> software for this device.
>
> I can use it on a PC with XP without a problem.
>
> Thanks again
> Lewis
>
>
>
>
>
> "glee" <[email protected]> wrote in message
> news:eLScoY\[email protected]...
> > Are we supposed to know what a "Rave.mp 256" is? From your description, I
> am
> > guessing it is some sort of USB device....perhaps an mp3 player of some
> sort??
> >
> > What won't "boot up"? The computer "boots"....a USB device is "detected".
> Do you
> > mean the USB device is not being detected in My Computer?
> >
> > --
> > Glen Ventura, MS MVP Shell/User, A+
> > http://dts-l.org/goodpost.htm
> > http://www.microsoft.com/communities/conduct/default.ms...
> >
> >
> > "Lewis" <[email protected]> wrote in message
> > > I have run the CD and installed win98se driver.
> > > But I can't get my pc to run the Rave.mp 256. I have tried everything I
> can
> > > think of. This USB port works fine, I use it for my Flash drives without
> a
> > > problem.The rave says " USB connected " it just won't boot-up at all in
> win
> > > explorer.
> > > Is there someone out there that may of had the problem?
> > > Is there a way to force the driver install?
> > >
> > > Thanks
> > > acer
> > >
> > >
> >
>
>
April 24, 2005 7:50:14 AM
I think it's showing up in my Generic USB Hub under the power tab as a
Unknown USB Device.
And there isn't anything I can do with it there.
thanks
Lewis
"glee" <[email protected]> wrote in message
news:%[email protected]...
> Right click on "My Computer" then left click on "Properties".
> Click on the "Device Manager" tab, then double-click the "Disk drives"
category to
> expand it.
> Look for your mp3 player model number in the list and double-click it (It
will not
> be one of the GENERIC drives).
> Click on the "Settings" tab, click to put a check in the box for
"Removable", click
> "OK", then "Close", and reboot.
>
> Note: It may be listed under another category than "Disk Drives", so if
not there,
> check other categories.
> --
> Glen Ventura, MS MVP Shell/User, A+
> http://dts-l.org/goodpost.htm
> http://www.microsoft.com/communities/conduct/default.ms...
>
>
> "Lewis" <[email protected]> wrote in message
> > Thank you.
> >
> > Yes, it is a mp3 player and yes it is a USB device that is not being
> > detected.
> > I installed the driver for Win98se from the CD that came with the
player.
> > But when I plug it in to the USB port, the new hardware wizard pops up.
> > I send it to the install CD/ driver file. Then it says it can't find
> > software for this device.
> >
> > I can use it on a PC with XP without a problem.
> >
> > Thanks again
> > Lewis
> >
> >
> >
> >
> >
> > "glee" <[email protected]> wrote in message
> > news:eLScoY\[email protected]...
> > > Are we supposed to know what a "Rave.mp 256" is? From your
description, I
> > am
> > > guessing it is some sort of USB device....perhaps an mp3 player of
some
> > sort??
> > >
> > > What won't "boot up"? The computer "boots"....a USB device is
"detected".
> > Do you
> > > mean the USB device is not being detected in My Computer?
> > >
> > > --
> > > Glen Ventura, MS MVP Shell/User, A+
> > > http://dts-l.org/goodpost.htm
> > > http://www.microsoft.com/communities/conduct/default.ms...
> > >
> > >
> > > "Lewis" <[email protected]> wrote in message
> > > > I have run the CD and installed win98se driver.
> > > > But I can't get my pc to run the Rave.mp 256. I have tried
everything I
> > can
> > > > think of. This USB port works fine, I use it for my Flash drives
without
> > a
> > > > problem.The rave says " USB connected " it just won't boot-up at all
in
> > win
> > > > explorer.
> > > > Is there someone out there that may of had the problem?
> > > > Is there a way to force the driver install?
> > > >
> > > > Thanks
> > > > acer
> > > >
> > > >
> > >
> >
> >
>
Anonymous
April 24, 2005 7:50:15 AM
It should be showing up there with its name, rather than as an unknown USB device.
It should also be appearing in Device Manager under the Disk Drives category. If it
does not, there is apparently a configuration problem, or the drivers are not
properly installed, or are defective. Have you tried uninstalling any
drivers/software that came with the player, and then reinstalling it following the
manufacturer's procedure, step by step?
Are you plugging it into a USB 1.1 or a USB 2.0 port? Is the port an onboard port
directly attached to the motherboard, or is it an add-on PCI USB card? The fact
that the player works fine when you boot to WinXP shows that the hardware seems to
be OK, so it has to be in the configuration and/or the drivers for 98.
Exactly what procedure did you follow to install it in Win98?
--
Glen Ventura, MS MVP Shell/User, A+
http://dts-l.org/goodpost.htm
http://www.microsoft.com/communities/conduct/default.ms...
> I think it's showing up in my Generic USB Hub under the power tab as a
> Unknown USB Device.
> And there isn't anything I can do with it there.
> thanks
> Lewis
>
>
>
> "glee" <[email protected]> wrote in message
> news:%[email protected]...
> > Right click on "My Computer" then left click on "Properties".
> > Click on the "Device Manager" tab, then double-click the "Disk drives"
> category to
> > expand it.
> > Look for your mp3 player model number in the list and double-click it (It
> will not
> > be one of the GENERIC drives).
> > Click on the "Settings" tab, click to put a check in the box for
> "Removable", click
> > "OK", then "Close", and reboot.
> >
> > Note: It may be listed under another category than "Disk Drives", so if
> not there,
> > check other categories.
> > --
> > Glen Ventura, MS MVP Shell/User, A+
> > http://dts-l.org/goodpost.htm
> > http://www.microsoft.com/communities/conduct/default.ms...
> >
> >
> > "Lewis" <[email protected]> wrote in message
> > > Thank you.
> > >
> > > Yes, it is a mp3 player and yes it is a USB device that is not being
> > > detected.
> > > I installed the driver for Win98se from the CD that came with the
> player.
> > > But when I plug it in to the USB port, the new hardware wizard pops up.
> > > I send it to the install CD/ driver file. Then it says it can't find
> > > software for this device.
> > >
> > > I can use it on a PC with XP without a problem.
> > >
> > > Thanks again
> > > Lewis
> > >
> > >
> > >
> > >
> > >
> > > "glee" <[email protected]> wrote in message
> > > news:eLScoY\[email protected]...
> > > > Are we supposed to know what a "Rave.mp 256" is? From your
> description, I
> > > am
> > > > guessing it is some sort of USB device....perhaps an mp3 player of
> some
> > > sort??
> > > >
> > > > What won't "boot up"? The computer "boots"....a USB device is
> "detected".
> > > Do you
> > > > mean the USB device is not being detected in My Computer?
> > > >
> > > > Read here:
> > > > --
> > > > Glen Ventura, MS MVP Shell/User, A+
> > > > http://dts-l.org/goodpost.htm
> > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > >
> > > >
> > > > "Lewis" <[email protected]> wrote in message
> > > > > I have run the CD and installed win98se driver.
> > > > > But I can't get my pc to run the Rave.mp 256. I have tried
> everything I
> > > can
> > > > > think of. This USB port works fine, I use it for my Flash drives
> without
> > > a
> > > > > problem.The rave says " USB connected " it just won't boot-up at all
> in
> > > win
> > > > > explorer.
> > > > > Is there someone out there that may of had the problem?
> > > > > Is there a way to force the driver install?
> > > > >
> > > > > Thanks
> > > > > acer
> > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>
Anonymous
April 24, 2005 7:50:15 AM
Lewis,
You *do* have Win98SE installed, not the original Win98, correct?
--
Glen Ventura, MS MVP Shell/User, A+
http://dts-l.org/goodpost.htm
http://www.microsoft.com/communities/conduct/default.ms...
> I think it's showing up in my Generic USB Hub under the power tab as a
> Unknown USB Device.
> And there isn't anything I can do with it there.
> thanks
> Lewis
>
>
>
> "glee" <[email protected]> wrote in message
> news:%[email protected]...
> > Right click on "My Computer" then left click on "Properties".
> > Click on the "Device Manager" tab, then double-click the "Disk drives"
> category to
> > expand it.
> > Look for your mp3 player model number in the list and double-click it (It
> will not
> > be one of the GENERIC drives).
> > Click on the "Settings" tab, click to put a check in the box for
> "Removable", click
> > "OK", then "Close", and reboot.
> >
> > Note: It may be listed under another category than "Disk Drives", so if
> not there,
> > check other categories.
> > --
> > Glen Ventura, MS MVP Shell/User, A+
> > http://dts-l.org/goodpost.htm
> > http://www.microsoft.com/communities/conduct/default.ms...
> >
> >
> > "Lewis" <[email protected]> wrote in message
> > > Thank you.
> > >
> > > Yes, it is a mp3 player and yes it is a USB device that is not being
> > > detected.
> > > I installed the driver for Win98se from the CD that came with the
> player.
> > > But when I plug it in to the USB port, the new hardware wizard pops up.
> > > I send it to the install CD/ driver file. Then it says it can't find
> > > software for this device.
> > >
> > > I can use it on a PC with XP without a problem.
> > >
> > > Thanks again
> > > Lewis
> > >
> > >
> > >
> > >
> > >
> > > "glee" <[email protected]> wrote in message
> > > news:eLScoY\[email protected]...
> > > > Are we supposed to know what a "Rave.mp 256" is? From your
> description, I
> > > am
> > > > guessing it is some sort of USB device....perhaps an mp3 player of
> some
> > > sort??
> > > >
> > > > What won't "boot up"? The computer "boots"....a USB device is
> "detected".
> > > Do you
> > > > mean the USB device is not being detected in My Computer?
> > > >
> > > > Read here:
> > > > --
> > > > Glen Ventura, MS MVP Shell/User, A+
> > > > http://dts-l.org/goodpost.htm
> > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > >
> > > >
> > > > "Lewis" <[email protected]> wrote in message
> > > > > I have run the CD and installed win98se driver.
> > > > > But I can't get my pc to run the Rave.mp 256. I have tried
> everything I
> > > can
> > > > > think of. This USB port works fine, I use it for my Flash drives
> without
> > > a
> > > > > problem.The rave says " USB connected " it just won't boot-up at all
> in
> > > win
> > > > > explorer.
> > > > > Is there someone out there that may of had the problem?
> > > > > Is there a way to force the driver install?
> > > > >
> > > > > Thanks
> > > > > acer
> > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>
April 25, 2005 1:06:26 AM
I'm using USB 1.1 ports, I have four ports onboard, of which I use one for
a add-on front mount card reader, that has four card slots and one USB 1.1
port.
I have tried all the ports and get the same results.
I have tried the manufacturer's procedure many times.It calls for installing
driver first. Then you plug in the mp3 player.
But each time I do that, the new hardware wizard pops up and ask for driver
for this device.
I have canceled at times and there is a no go.
And I have sent it to the driver file on the manufacturer's CD. And it says
unable to locate driver.
"glee" <[email protected]> wrote in message
news:[email protected]...
> It should be showing up there with its name, rather than as an unknown USB
device.
> It should also be appearing in Device Manager under the Disk Drives
category. If it
> does not, there is apparently a configuration problem, or the drivers are
not
> properly installed, or are defective. Have you tried uninstalling any
> drivers/software that came with the player, and then reinstalling it
following the
> manufacturer's procedure, step by step?
>
> Are you plugging it into a USB 1.1 or a USB 2.0 port? Is the port an
onboard port
> directly attached to the motherboard, or is it an add-on PCI USB card?
The fact
> that the player works fine when you boot to WinXP shows that the hardware
seems to
> be OK, so it has to be in the configuration and/or the drivers for 98.
>
> Exactly what procedure did you follow to install it in Win98?
> --
> Glen Ventura, MS MVP Shell/User, A+
> http://dts-l.org/goodpost.htm
> http://www.microsoft.com/communities/conduct/default.ms...
>
> "Lewis" <[email protected]> wrote in message
> > I think it's showing up in my Generic USB Hub under the power tab as a
> > Unknown USB Device.
> > And there isn't anything I can do with it there.
> > thanks
> > Lewis
> >
> >
> >
> > "glee" <[email protected]> wrote in message
> > news:%[email protected]...
> > > Right click on "My Computer" then left click on "Properties".
> > > Click on the "Device Manager" tab, then double-click the "Disk drives"
> > category to
> > > expand it.
> > > Look for your mp3 player model number in the list and double-click it
(It
> > will not
> > > be one of the GENERIC drives).
> > > Click on the "Settings" tab, click to put a check in the box for
> > "Removable", click
> > > "OK", then "Close", and reboot.
> > >
> > > Note: It may be listed under another category than "Disk Drives", so
if
> > not there,
> > > check other categories.
> > > --
> > > Glen Ventura, MS MVP Shell/User, A+
> > > http://dts-l.org/goodpost.htm
> > > http://www.microsoft.com/communities/conduct/default.ms...
> > >
> > >
> > > "Lewis" <[email protected]> wrote in message
> > > > Thank you.
> > > >
> > > > Yes, it is a mp3 player and yes it is a USB device that is not
being
> > > > detected.
> > > > I installed the driver for Win98se from the CD that came with the
> > player.
> > > > But when I plug it in to the USB port, the new hardware wizard pops
up.
> > > > I send it to the install CD/ driver file. Then it says it can't find
> > > > software for this device.
> > > >
> > > > I can use it on a PC with XP without a problem.
> > > >
> > > > Thanks again
> > > > Lewis
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > "glee" <[email protected]> wrote in message
> > > > news:eLScoY\[email protected]...
> > > > > Are we supposed to know what a "Rave.mp 256" is? From your
> > description, I
> > > > am
> > > > > guessing it is some sort of USB device....perhaps an mp3 player of
> > some
> > > > sort??
> > > > >
> > > > > What won't "boot up"? The computer "boots"....a USB device is
> > "detected".
> > > > Do you
> > > > > mean the USB device is not being detected in My Computer?
> > > > >
> > > > > Read here:
> > > > > http://dts-l.org/goodpost.htm and post back with more info.
> > > > > --
> > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > http://dts-l.org/goodpost.htm
> > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > >
> > > > >
> > > > > "Lewis" <[email protected]> wrote in message
> > > > > > I have run the CD and installed win98se driver.
> > > > > > But I can't get my pc to run the Rave.mp 256. I have tried
> > everything I
> > > > can
> > > > > > think of. This USB port works fine, I use it for my Flash drives
> > without
> > > > a
> > > > > > problem.The rave says " USB connected " it just won't boot-up at
all
> > in
> > > > win
> > > > > > explorer.
> > > > > > Is there someone out there that may of had the problem?
> > > > > > Is there a way to force the driver install?
> > > > > >
> > > > > > Thanks
> > > > > > acer
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>
Anonymous
April 25, 2005 1:06:27 AM
I can't tell for sure what is going on but after you install the driver from the
disc, you should re-boot, then plug in the device after Windows starts. If the New
Hardware wizard pops up, instead of inserting the CD again and pointing it there, I
would just have Windows search for the driver on your system, since the driver has
already been installed. Point it to the Windows\System folder; if no joy, point it
to the Windows\Inf folder and Windows\Inf\Other folder. Windows should locate the
just-installed driver. You should not be pointing it to the CD.
If you still have the problem after that, I would contact support for the device
manufacturer.
--
Glen Ventura, MS MVP Shell/User, A+
http://dts-l.org/goodpost.htm
http://www.microsoft.com/communities/conduct/default.ms...
> I'm using USB 1.1 ports, I have four ports onboard, of which I use one for
> a add-on front mount card reader, that has four card slots and one USB 1.1
> port.
>
> I have tried all the ports and get the same results.
> I have tried the manufacturer's procedure many times.It calls for installing
> driver first. Then you plug in the mp3 player.
> But each time I do that, the new hardware wizard pops up and ask for driver
> for this device.
> I have canceled at times and there is a no go.
> And I have sent it to the driver file on the manufacturer's CD. And it says
> unable to locate driver.
>
> I really appreciate your help
>
>
> "glee" <[email protected]> wrote in message
> news:[email protected]...
> > It should be showing up there with its name, rather than as an unknown USB
> device.
> > It should also be appearing in Device Manager under the Disk Drives
> category. If it
> > does not, there is apparently a configuration problem, or the drivers are
> not
> > properly installed, or are defective. Have you tried uninstalling any
> > drivers/software that came with the player, and then reinstalling it
> following the
> > manufacturer's procedure, step by step?
> >
> > Are you plugging it into a USB 1.1 or a USB 2.0 port? Is the port an
> onboard port
> > directly attached to the motherboard, or is it an add-on PCI USB card?
> The fact
> > that the player works fine when you boot to WinXP shows that the hardware
> seems to
> > be OK, so it has to be in the configuration and/or the drivers for 98.
> >
> > Exactly what procedure did you follow to install it in Win98?
> > --
> > Glen Ventura, MS MVP Shell/User, A+
> > http://dts-l.org/goodpost.htm
> > http://www.microsoft.com/communities/conduct/default.ms...
> >
> > "Lewis" <[email protected]> wrote in message
> > > I think it's showing up in my Generic USB Hub under the power tab as a
> > > Unknown USB Device.
> > > And there isn't anything I can do with it there.
> > > thanks
> > > Lewis
> > >
> > >
> > >
> > > "glee" <[email protected]> wrote in message
> > > news:%[email protected]...
> > > > Right click on "My Computer" then left click on "Properties".
> > > > Click on the "Device Manager" tab, then double-click the "Disk drives"
> > > category to
> > > > expand it.
> > > > Look for your mp3 player model number in the list and double-click it
> (It
> > > will not
> > > > be one of the GENERIC drives).
> > > > Click on the "Settings" tab, click to put a check in the box for
> > > "Removable", click
> > > > "OK", then "Close", and reboot.
> > > >
> > > > Note: It may be listed under another category than "Disk Drives", so
> if
> > > not there,
> > > > check other categories.
> > > > --
> > > > Glen Ventura, MS MVP Shell/User, A+
> > > > http://dts-l.org/goodpost.htm
> > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > >
> > > >
> > > > "Lewis" <[email protected]> wrote in message
> > > > > Thank you.
> > > > >
> > > > > Yes, it is a mp3 player and yes it is a USB device that is not
> being
> > > > > detected.
> > > > > I installed the driver for Win98se from the CD that came with the
> > > player.
> > > > > But when I plug it in to the USB port, the new hardware wizard pops
> up.
> > > > > I send it to the install CD/ driver file. Then it says it can't find
> > > > > software for this device.
> > > > >
> > > > > I can use it on a PC with XP without a problem.
> > > > >
> > > > > Thanks again
> > > > > Lewis
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > "glee" <[email protected]> wrote in message
> > > > > news:eLScoY\[email protected]...
> > > > > > Are we supposed to know what a "Rave.mp 256" is? From your
> > > description, I
> > > > > am
> > > > > > guessing it is some sort of USB device....perhaps an mp3 player of
> > > some
> > > > > sort??
> > > > > >
> > > > > > What won't "boot up"? The computer "boots"....a USB device is
> > > "detected".
> > > > > Do you
> > > > > > mean the USB device is not being detected in My Computer?
> > > > > >
> > > > > > Read here:
> > > > > > http://dts-l.org/goodpost.htm and post back with more info.
> > > > > > --
> > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > http://dts-l.org/goodpost.htm
> > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > >
> > > > > >
> > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > I have run the CD and installed win98se driver.
> > > > > > > But I can't get my pc to run the Rave.mp 256. I have tried
> > > everything I
> > > > > can
> > > > > > > think of. This USB port works fine, I use it for my Flash drives
> > > without
> > > > > a
> > > > > > > problem.The rave says " USB connected " it just won't boot-up at
> all
> > > in
> > > > > win
> > > > > > > explorer.
> > > > > > > Is there someone out there that may of had the problem?
> > > > > > > Is there a way to force the driver install?
> > > > > > >
> > > > > > > Thanks
> > > > > > > acer
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>
April 25, 2005 2:20:48 AM
I do have Win98SE installed.
"glee" <[email protected]> wrote in message
news:[email protected]...
> Lewis,
> You *do* have Win98SE installed, not the original Win98, correct?
> --
> Glen Ventura, MS MVP Shell/User, A+
> http://dts-l.org/goodpost.htm
> http://www.microsoft.com/communities/conduct/default.ms...
>
> "Lewis" <[email protected]> wrote in message
> > I think it's showing up in my Generic USB Hub under the power tab as a
> > Unknown USB Device.
> > And there isn't anything I can do with it there.
> > thanks
> > Lewis
> >
> >
> >
> > "glee" <[email protected]> wrote in message
> > news:%[email protected]...
> > > Right click on "My Computer" then left click on "Properties".
> > > Click on the "Device Manager" tab, then double-click the "Disk drives"
> > category to
> > > expand it.
> > > Look for your mp3 player model number in the list and double-click it
(It
> > will not
> > > be one of the GENERIC drives).
> > > Click on the "Settings" tab, click to put a check in the box for
> > "Removable", click
> > > "OK", then "Close", and reboot.
> > >
> > > Note: It may be listed under another category than "Disk Drives", so
if
> > not there,
> > > check other categories.
> > > --
> > > Glen Ventura, MS MVP Shell/User, A+
> > > http://dts-l.org/goodpost.htm
> > > http://www.microsoft.com/communities/conduct/default.ms...
> > >
> > >
> > > "Lewis" <[email protected]> wrote in message
> > > > Thank you.
> > > >
> > > > Yes, it is a mp3 player and yes it is a USB device that is not
being
> > > > detected.
> > > > I installed the driver for Win98se from the CD that came with the
> > player.
> > > > But when I plug it in to the USB port, the new hardware wizard pops
up.
> > > > I send it to the install CD/ driver file. Then it says it can't find
> > > > software for this device.
> > > >
> > > > I can use it on a PC with XP without a problem.
> > > >
> > > > Thanks again
> > > > Lewis
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > "glee" <[email protected]> wrote in message
> > > > news:eLScoY\[email protected]...
> > > > > Are we supposed to know what a "Rave.mp 256" is? From your
> > description, I
> > > > am
> > > > > guessing it is some sort of USB device....perhaps an mp3 player of
> > some
> > > > sort??
> > > > >
> > > > > What won't "boot up"? The computer "boots"....a USB device is
> > "detected".
> > > > Do you
> > > > > mean the USB device is not being detected in My Computer?
> > > > >
> > > > > Read here:
> > > > > http://dts-l.org/goodpost.htm and post back with more info.
> > > > > --
> > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > http://dts-l.org/goodpost.htm
> > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > >
> > > > >
> > > > > "Lewis" <[email protected]> wrote in message
> > > > > > I have run the CD and installed win98se driver.
> > > > > > But I can't get my pc to run the Rave.mp 256. I have tried
> > everything I
> > > > can
> > > > > > think of. This USB port works fine, I use it for my Flash drives
> > without
> > > > a
> > > > > > problem.The rave says " USB connected " it just won't boot-up at
all
> > in
> > > > win
> > > > > > explorer.
> > > > > > Is there someone out there that may of had the problem?
> > > > > > Is there a way to force the driver install?
> > > > > >
> > > > > > Thanks
> > > > > > acer
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>
April 25, 2005 4:19:30 PM
I have done everything you suggested. no joy!!!
It's crazy, because when I point to the windows\system32\drivers- with
hardware wizard.
It just doesn't allow me to choose the drivers file, it will let choose -
windows\system32.
However, it says, drivers can't be found.
But I can use explorer to see the driver software, but windows just won't
let me use them.
It drives me crazy, I can see it , but I can't force it to use the software.
I contacted manufacturer support for the device first. And they said that
the driver works and that it must be a windows problem.
Also, I can't find ( Windows\Inf\Other folder ) either.
I can't believe that I'm the only one that has run into this problem.
Lewis
"glee" <[email protected]> wrote in message
news:%[email protected]...
> I can't tell for sure what is going on but after you install the driver
from the
> disc, you should re-boot, then plug in the device after Windows starts.
If the New
> Hardware wizard pops up, instead of inserting the CD again and pointing it
there, I
> would just have Windows search for the driver on your system, since the
driver has
> already been installed. Point it to the Windows\System folder; if no
joy, point it
> to the Windows\Inf folder and Windows\Inf\Other folder. Windows should
locate the
> just-installed driver. You should not be pointing it to the CD.
> If you still have the problem after that, I would contact support for the
device
> manufacturer.
> --
> Glen Ventura, MS MVP Shell/User, A+
> http://dts-l.org/goodpost.htm
> http://www.microsoft.com/communities/conduct/default.ms...
>
>
> "Lewis" <[email protected]> wrote in message
> > I'm using USB 1.1 ports, I have four ports onboard, of which I use one
for
> > a add-on front mount card reader, that has four card slots and one USB
1.1
> > port.
> >
> > I have tried all the ports and get the same results.
> > I have tried the manufacturer's procedure many times.It calls for
installing
> > driver first. Then you plug in the mp3 player.
> > But each time I do that, the new hardware wizard pops up and ask for
driver
> > for this device.
> > I have canceled at times and there is a no go.
> > And I have sent it to the driver file on the manufacturer's CD. And it
says
> > unable to locate driver.
> >
> > I really appreciate your help
> >
> >
> > "glee" <[email protected]> wrote in message
> > news:[email protected]...
> > > It should be showing up there with its name, rather than as an unknown
USB
> > device.
> > > It should also be appearing in Device Manager under the Disk Drives
> > category. If it
> > > does not, there is apparently a configuration problem, or the drivers
are
> > not
> > > properly installed, or are defective. Have you tried uninstalling any
> > > drivers/software that came with the player, and then reinstalling it
> > following the
> > > manufacturer's procedure, step by step?
> > >
> > > Are you plugging it into a USB 1.1 or a USB 2.0 port? Is the port an
> > onboard port
> > > directly attached to the motherboard, or is it an add-on PCI USB card?
> > The fact
> > > that the player works fine when you boot to WinXP shows that the
hardware
> > seems to
> > > be OK, so it has to be in the configuration and/or the drivers for 98.
> > >
> > > Exactly what procedure did you follow to install it in Win98?
> > > --
> > > Glen Ventura, MS MVP Shell/User, A+
> > > http://dts-l.org/goodpost.htm
> > > http://www.microsoft.com/communities/conduct/default.ms...
> > >
> > > "Lewis" <[email protected]> wrote in message
> > > > I think it's showing up in my Generic USB Hub under the power tab as
a
> > > > Unknown USB Device.
> > > > And there isn't anything I can do with it there.
> > > > thanks
> > > > Lewis
> > > >
> > > >
> > > >
> > > > "glee" <[email protected]> wrote in message
> > > > news:%[email protected]...
> > > > > Right click on "My Computer" then left click on "Properties".
> > > > > Click on the "Device Manager" tab, then double-click the "Disk
drives"
> > > > category to
> > > > > expand it.
> > > > > Look for your mp3 player model number in the list and double-click
it
> > (It
> > > > will not
> > > > > be one of the GENERIC drives).
> > > > > Click on the "Settings" tab, click to put a check in the box for
> > > > "Removable", click
> > > > > "OK", then "Close", and reboot.
> > > > >
> > > > > Note: It may be listed under another category than "Disk Drives",
so
> > if
> > > > not there,
> > > > > check other categories.
> > > > > --
> > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > http://dts-l.org/goodpost.htm
> > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > >
> > > > >
> > > > > "Lewis" <[email protected]> wrote in message
> > > > > > Thank you.
> > > > > >
> > > > > > Yes, it is a mp3 player and yes it is a USB device that is not
> > being
> > > > > > detected.
> > > > > > I installed the driver for Win98se from the CD that came with
the
> > > > player.
> > > > > > But when I plug it in to the USB port, the new hardware wizard
pops
> > up.
> > > > > > I send it to the install CD/ driver file. Then it says it can't
find
> > > > > > software for this device.
> > > > > >
> > > > > > I can use it on a PC with XP without a problem.
> > > > > >
> > > > > > Thanks again
> > > > > > Lewis
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > "glee" <[email protected]> wrote in message
> > > > > > news:eLScoY\[email protected]...
> > > > > > > Are we supposed to know what a "Rave.mp 256" is? From your
> > > > description, I
> > > > > > am
> > > > > > > guessing it is some sort of USB device....perhaps an mp3
player of
> > > > some
> > > > > > sort??
> > > > > > >
> > > > > > > What won't "boot up"? The computer "boots"....a USB device is
> > > > "detected".
> > > > > > Do you
> > > > > > > mean the USB device is not being detected in My Computer?
> > > > > > >
> > > > > > > Read here:
> > > > > > > http://dts-l.org/goodpost.htm and post back with more info.
> > > > > > > --
> > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > >
> > > > > > >
> > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > I have run the CD and installed win98se driver.
> > > > > > > > But I can't get my pc to run the Rave.mp 256. I have tried
> > > > everything I
> > > > > > can
> > > > > > > > think of. This USB port works fine, I use it for my Flash
drives
> > > > without
> > > > > > a
> > > > > > > > problem.The rave says " USB connected " it just won't
boot-up at
> > all
> > > > in
> > > > > > win
> > > > > > > > explorer.
> > > > > > > > Is there someone out there that may of had the problem?
> > > > > > > > Is there a way to force the driver install?
> > > > > > > >
> > > > > > > > Thanks
> > > > > > > > acer
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>
Anonymous
April 25, 2005 6:05:34 PM
Right, you only can point the wizard (or any installer) to the folder containing
your drivers. It has to look for the type of file it wants, and must see the
correct identifying info.......but, in Win9x, you would be pointing to the
Windows\System folder, not the System32 or System32\Drivers folder. If the wizard
does not find what it wants in the System folder, point to the Windows\Inf folder.
You may not have an Inf\Other sub-folder.....not all systems do.
I am running out of ideas, if the ports work for everything else, and the device
works on other operating systems. Can you try the device on another Win98SE
computer to see if it installs there? A friend of mine could not get a USB printer
to install on his machine, and I got it to install on mine, but I had to hand-feed
the installer the location of the .cat file to get it installed. I then went to his
machine and installed the printer no problem, once I knew what the issue was.
without trying the installation myself, it is hard to see where yours might be
failing. :-\
--
Glen Ventura, MS MVP Shell/User, A+
http://dts-l.org/goodpost.htm
http://www.microsoft.com/communities/conduct/default.ms...
> Glee, thanks for your time.
>
> I have done everything you suggested. no joy!!!
> It's crazy, because when I point to the windows\system32\drivers- with
> hardware wizard.
> It just doesn't allow me to choose the drivers file, it will let choose -
> windows\system32.
> However, it says, drivers can't be found.
> But I can use explorer to see the driver software, but windows just won't
> let me use them.
> It drives me crazy, I can see it , but I can't force it to use the software.
>
> I contacted manufacturer support for the device first. And they said that
> the driver works and that it must be a windows problem.
> Also, I can't find ( Windows\Inf\Other folder ) either.
>
> I can't believe that I'm the only one that has run into this problem.
>
> Thanks again for your time.
>
> Lewis
>
>
>
>
>
>
>
> "glee" <[email protected]> wrote in message
> news:%[email protected]...
> > I can't tell for sure what is going on but after you install the driver
> from the
> > disc, you should re-boot, then plug in the device after Windows starts.
> If the New
> > Hardware wizard pops up, instead of inserting the CD again and pointing it
> there, I
> > would just have Windows search for the driver on your system, since the
> driver has
> > already been installed. Point it to the Windows\System folder; if no
> joy, point it
> > to the Windows\Inf folder and Windows\Inf\Other folder. Windows should
> locate the
> > just-installed driver. You should not be pointing it to the CD.
> > If you still have the problem after that, I would contact support for the
> device
> > manufacturer.
> > --
> > Glen Ventura, MS MVP Shell/User, A+
> > http://dts-l.org/goodpost.htm
> > http://www.microsoft.com/communities/conduct/default.ms...
> >
> >
> > "Lewis" <[email protected]> wrote in message
> > > I'm using USB 1.1 ports, I have four ports onboard, of which I use one
> for
> > > a add-on front mount card reader, that has four card slots and one USB
> 1.1
> > > port.
> > >
> > > I have tried all the ports and get the same results.
> > > I have tried the manufacturer's procedure many times.It calls for
> installing
> > > driver first. Then you plug in the mp3 player.
> > > But each time I do that, the new hardware wizard pops up and ask for
> driver
> > > for this device.
> > > I have canceled at times and there is a no go.
> > > And I have sent it to the driver file on the manufacturer's CD. And it
> says
> > > unable to locate driver.
> > >
> > > I really appreciate your help
> > >
> > >
> > > "glee" <[email protected]> wrote in message
> > > news:[email protected]...
> > > > It should be showing up there with its name, rather than as an unknown
> USB
> > > device.
> > > > It should also be appearing in Device Manager under the Disk Drives
> > > category. If it
> > > > does not, there is apparently a configuration problem, or the drivers
> are
> > > not
> > > > properly installed, or are defective. Have you tried uninstalling any
> > > > drivers/software that came with the player, and then reinstalling it
> > > following the
> > > > manufacturer's procedure, step by step?
> > > >
> > > > Are you plugging it into a USB 1.1 or a USB 2.0 port? Is the port an
> > > onboard port
> > > > directly attached to the motherboard, or is it an add-on PCI USB card?
> > > The fact
> > > > that the player works fine when you boot to WinXP shows that the
> hardware
> > > seems to
> > > > be OK, so it has to be in the configuration and/or the drivers for 98.
> > > >
> > > > Exactly what procedure did you follow to install it in Win98?
> > > > --
> > > > Glen Ventura, MS MVP Shell/User, A+
> > > > http://dts-l.org/goodpost.htm
> > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > >
> > > > "Lewis" <[email protected]> wrote in message
> > > > > I think it's showing up in my Generic USB Hub under the power tab as
> a
> > > > > Unknown USB Device.
> > > > > And there isn't anything I can do with it there.
> > > > > thanks
> > > > > Lewis
> > > > >
> > > > >
> > > > >
> > > > > "glee" <[email protected]> wrote in message
> > > > > news:%[email protected]...
> > > > > > Right click on "My Computer" then left click on "Properties".
> > > > > > Click on the "Device Manager" tab, then double-click the "Disk
> drives"
> > > > > category to
> > > > > > expand it.
> > > > > > Look for your mp3 player model number in the list and double-click
> it
> > > (It
> > > > > will not
> > > > > > be one of the GENERIC drives).
> > > > > > Click on the "Settings" tab, click to put a check in the box for
> > > > > "Removable", click
> > > > > > "OK", then "Close", and reboot.
> > > > > >
> > > > > > Note: It may be listed under another category than "Disk Drives",
> so
> > > if
> > > > > not there,
> > > > > > check other categories.
> > > > > > --
> > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > http://dts-l.org/goodpost.htm
> > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > >
> > > > > >
> > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > Thank you.
> > > > > > >
> > > > > > > Yes, it is a mp3 player and yes it is a USB device that is not
> > > being
> > > > > > > detected.
> > > > > > > I installed the driver for Win98se from the CD that came with
> the
> > > > > player.
> > > > > > > But when I plug it in to the USB port, the new hardware wizard
> pops
> > > up.
> > > > > > > I send it to the install CD/ driver file. Then it says it can't
> find
> > > > > > > software for this device.
> > > > > > >
> > > > > > > I can use it on a PC with XP without a problem.
> > > > > > >
> > > > > > > Thanks again
> > > > > > > Lewis
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > "glee" <[email protected]> wrote in message
> > > > > > > news:eLScoY\[email protected]...
> > > > > > > > Are we supposed to know what a "Rave.mp 256" is? From your
> > > > > description, I
> > > > > > > am
> > > > > > > > guessing it is some sort of USB device....perhaps an mp3
> player of
> > > > > some
> > > > > > > sort??
> > > > > > > >
> > > > > > > > What won't "boot up"? The computer "boots"....a USB device is
> > > > > "detected".
> > > > > > > Do you
> > > > > > > > mean the USB device is not being detected in My Computer?
> > > > > > > >
> > > > > > > > Read here:
> > > > > > > > http://dts-l.org/goodpost.htm and post back with more info.
> > > > > > > > --
> > > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > > >
> > > > > > > >
> > > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > > I have run the CD and installed win98se driver.
> > > > > > > > > But I can't get my pc to run the Rave.mp 256. I have tried
> > > > > everything I
> > > > > > > can
> > > > > > > > > think of. This USB port works fine, I use it for my Flash
> drives
> > > > > without
> > > > > > > a
> > > > > > > > > problem.The rave says " USB connected " it just won't
> boot-up at
> > > all
> > > > > in
> > > > > > > win
> > > > > > > > > explorer.
> > > > > > > > > Is there someone out there that may of had the problem?
> > > > > > > > > Is there a way to force the driver install?
> > > > > > > > >
> > > > > > > > > Thanks
> > > > > > > > > acer
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>
April 26, 2005 8:21:51 AM
Well, I will have to find a win98se PC somewhere to try this device.
But in the mean time, I went to --windows\system32 and copied the 2 driver
files that I could see.
I then put them in-- windows\system folder. And rebooted-- no joy.
So I left them there and removed the 2 files from system32 and rebooted-- no
joy.
There is a firmware update out for this USB device, do you think that would
help?
But then I can't install it, if my mp3 doesn't boot up on this PC.
Thanks Glee
Lewis
"glee" <[email protected]> wrote in message
news:[email protected]...
> Right, you only can point the wizard (or any installer) to the folder
containing
> your drivers. It has to look for the type of file it wants, and must see
the
> correct identifying info.......but, in Win9x, you would be pointing to the
> Windows\System folder, not the System32 or System32\Drivers folder. If
the wizard
> does not find what it wants in the System folder, point to the Windows\Inf
folder.
> You may not have an Inf\Other sub-folder.....not all systems do.
> I am running out of ideas, if the ports work for everything else, and the
device
> works on other operating systems. Can you try the device on another
Win98SE
> computer to see if it installs there? A friend of mine could not get a
USB printer
> to install on his machine, and I got it to install on mine, but I had to
hand-feed
> the installer the location of the .cat file to get it installed. I then
went to his
> machine and installed the printer no problem, once I knew what the issue
was.
> without trying the installation myself, it is hard to see where yours
might be
> failing. :-\
> --
> Glen Ventura, MS MVP Shell/User, A+
> http://dts-l.org/goodpost.htm
> http://www.microsoft.com/communities/conduct/default.ms...
>
>
> "Lewis" <[email protected]> wrote in message
> > Glee, thanks for your time.
> >
> > I have done everything you suggested. no joy!!!
> > It's crazy, because when I point to the windows\system32\drivers- with
> > hardware wizard.
> > It just doesn't allow me to choose the drivers file, it will let
choose -
> > windows\system32.
> > However, it says, drivers can't be found.
> > But I can use explorer to see the driver software, but windows just
won't
> > let me use them.
> > It drives me crazy, I can see it , but I can't force it to use the
software.
> >
> > I contacted manufacturer support for the device first. And they said
that
> > the driver works and that it must be a windows problem.
> > Also, I can't find ( Windows\Inf\Other folder ) either.
> >
> > I can't believe that I'm the only one that has run into this problem.
> >
> > Thanks again for your time.
> >
> > Lewis
> >
> >
> >
> >
> >
> >
> >
> > "glee" <[email protected]> wrote in message
> > news:%[email protected]...
> > > I can't tell for sure what is going on but after you install the
driver
> > from the
> > > disc, you should re-boot, then plug in the device after Windows
starts.
> > If the New
> > > Hardware wizard pops up, instead of inserting the CD again and
pointing it
> > there, I
> > > would just have Windows search for the driver on your system, since
the
> > driver has
> > > already been installed. Point it to the Windows\System folder; if no
> > joy, point it
> > > to the Windows\Inf folder and Windows\Inf\Other folder. Windows
should
> > locate the
> > > just-installed driver. You should not be pointing it to the CD.
> > > If you still have the problem after that, I would contact support for
the
> > device
> > > manufacturer.
> > > --
> > > Glen Ventura, MS MVP Shell/User, A+
> > > http://dts-l.org/goodpost.htm
> > > http://www.microsoft.com/communities/conduct/default.ms...
> > >
> > >
> > > "Lewis" <[email protected]> wrote in message
> > > > I'm using USB 1.1 ports, I have four ports onboard, of which I use
one
> > for
> > > > a add-on front mount card reader, that has four card slots and one
USB
> > 1.1
> > > > port.
> > > >
> > > > I have tried all the ports and get the same results.
> > > > I have tried the manufacturer's procedure many times.It calls for
> > installing
> > > > driver first. Then you plug in the mp3 player.
> > > > But each time I do that, the new hardware wizard pops up and ask for
> > driver
> > > > for this device.
> > > > I have canceled at times and there is a no go.
> > > > And I have sent it to the driver file on the manufacturer's CD. And
it
> > says
> > > > unable to locate driver.
> > > >
> > > > I really appreciate your help
> > > >
> > > >
> > > > "glee" <[email protected]> wrote in message
> > > > news:[email protected]...
> > > > > It should be showing up there with its name, rather than as an
unknown
> > USB
> > > > device.
> > > > > It should also be appearing in Device Manager under the Disk
Drives
> > > > category. If it
> > > > > does not, there is apparently a configuration problem, or the
drivers
> > are
> > > > not
> > > > > properly installed, or are defective. Have you tried uninstalling
any
> > > > > drivers/software that came with the player, and then reinstalling
it
> > > > following the
> > > > > manufacturer's procedure, step by step?
> > > > >
> > > > > Are you plugging it into a USB 1.1 or a USB 2.0 port? Is the port
an
> > > > onboard port
> > > > > directly attached to the motherboard, or is it an add-on PCI USB
card?
> > > > The fact
> > > > > that the player works fine when you boot to WinXP shows that the
> > hardware
> > > > seems to
> > > > > be OK, so it has to be in the configuration and/or the drivers for
98.
> > > > >
> > > > > Exactly what procedure did you follow to install it in Win98?
> > > > > --
> > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > http://dts-l.org/goodpost.htm
> > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > >
> > > > > "Lewis" <[email protected]> wrote in message
> > > > > > I think it's showing up in my Generic USB Hub under the power
tab as
> > a
> > > > > > Unknown USB Device.
> > > > > > And there isn't anything I can do with it there.
> > > > > > thanks
> > > > > > Lewis
> > > > > >
> > > > > >
> > > > > >
> > > > > > "glee" <[email protected]> wrote in message
> > > > > > news:%[email protected]...
> > > > > > > Right click on "My Computer" then left click on "Properties".
> > > > > > > Click on the "Device Manager" tab, then double-click the "Disk
> > drives"
> > > > > > category to
> > > > > > > expand it.
> > > > > > > Look for your mp3 player model number in the list and
double-click
> > it
> > > > (It
> > > > > > will not
> > > > > > > be one of the GENERIC drives).
> > > > > > > Click on the "Settings" tab, click to put a check in the box
for
> > > > > > "Removable", click
> > > > > > > "OK", then "Close", and reboot.
> > > > > > >
> > > > > > > Note: It may be listed under another category than "Disk
Drives",
> > so
> > > > if
> > > > > > not there,
> > > > > > > check other categories.
> > > > > > > --
> > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > >
> > > > > > >
> > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > Thank you.
> > > > > > > >
> > > > > > > > Yes, it is a mp3 player and yes it is a USB device that is
not
> > > > being
> > > > > > > > detected.
> > > > > > > > I installed the driver for Win98se from the CD that came
with
> > the
> > > > > > player.
> > > > > > > > But when I plug it in to the USB port, the new hardware
wizard
> > pops
> > > > up.
> > > > > > > > I send it to the install CD/ driver file. Then it says it
can't
> > find
> > > > > > > > software for this device.
> > > > > > > >
> > > > > > > > I can use it on a PC with XP without a problem.
> > > > > > > >
> > > > > > > > Thanks again
> > > > > > > > Lewis
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > "glee" <[email protected]> wrote in message
> > > > > > > > news:eLScoY\[email protected]...
> > > > > > > > > Are we supposed to know what a "Rave.mp 256" is? From
your
> > > > > > description, I
> > > > > > > > am
> > > > > > > > > guessing it is some sort of USB device....perhaps an mp3
> > player of
> > > > > > some
> > > > > > > > sort??
> > > > > > > > >
> > > > > > > > > What won't "boot up"? The computer "boots"....a USB
device is
> > > > > > "detected".
> > > > > > > > Do you
> > > > > > > > > mean the USB device is not being detected in My Computer?
> > > > > > > > >
> > > > > > > > > Read here:
> > > > > > > > > http://dts-l.org/goodpost.htm and post back with more
info.
> > > > > > > > > --
> > > > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > >
> > > > > > > > > > I have run the CD and installed win98se driver.
> > > > > > > > > > But I can't get my pc to run the Rave.mp 256. I have
tried
> > > > > > everything I
> > > > > > > > can
> > > > > > > > > > think of. This USB port works fine, I use it for my
Flash
> > drives
> > > > > > without
> > > > > > > > a
> > > > > > > > > > problem.The rave says " USB connected " it just won't
> > boot-up at
> > > > all
> > > > > > in
> > > > > > > > win
> > > > > > > > > > explorer.
> > > > > > > > > > Is there someone out there that may of had the problem?
> > > > > > > > > > Is there a way to force the driver install?
> > > > > > > > > >
> > > > > > > > > > Thanks
> > > > > > > > > > acer
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>
Anonymous
April 27, 2005 3:39:57 AM
I thought you said the device worked on WinXP. If so, you can update the firmware
there.
I didn't mean to suggest you move driver files from one folder to another.....only
meant to state that on Win98SE, the drivers files should install themselves to the
System folder as opposed to the System32 folder.
--
Glen Ventura, MS MVP Shell/User, A+
http://dts-l.org/goodpost.htm
http://www.microsoft.com/communities/conduct/default.ms...
> Well, I will have to find a win98se PC somewhere to try this device.
>
> But in the mean time, I went to --windows\system32 and copied the 2 driver
> files that I could see.
> I then put them in-- windows\system folder. And rebooted-- no joy.
> So I left them there and removed the 2 files from system32 and rebooted-- no
> joy.
>
> There is a firmware update out for this USB device, do you think that would
> help?
> But then I can't install it, if my mp3 doesn't boot up on this PC.
>
> Thanks Glee
> Lewis
>
>
>
> "glee" <[email protected]> wrote in message
> news:[email protected]...
> > Right, you only can point the wizard (or any installer) to the folder
> containing
> > your drivers. It has to look for the type of file it wants, and must see
> the
> > correct identifying info.......but, in Win9x, you would be pointing to the
> > Windows\System folder, not the System32 or System32\Drivers folder. If
> the wizard
> > does not find what it wants in the System folder, point to the Windows\Inf
> folder.
> > You may not have an Inf\Other sub-folder.....not all systems do.
> > I am running out of ideas, if the ports work for everything else, and the
> device
> > works on other operating systems. Can you try the device on another
> Win98SE
> > computer to see if it installs there? A friend of mine could not get a
> USB printer
> > to install on his machine, and I got it to install on mine, but I had to
> hand-feed
> > the installer the location of the .cat file to get it installed. I then
> went to his
> > machine and installed the printer no problem, once I knew what the issue
> was.
> > without trying the installation myself, it is hard to see where yours
> might be
> > failing. :-\
> > --
> > Glen Ventura, MS MVP Shell/User, A+
> > http://dts-l.org/goodpost.htm
> > http://www.microsoft.com/communities/conduct/default.ms...
> >
> >
> > "Lewis" <[email protected]> wrote in message
> > > Glee, thanks for your time.
> > >
> > > I have done everything you suggested. no joy!!!
> > > It's crazy, because when I point to the windows\system32\drivers- with
> > > hardware wizard.
> > > It just doesn't allow me to choose the drivers file, it will let
> choose -
> > > windows\system32.
> > > However, it says, drivers can't be found.
> > > But I can use explorer to see the driver software, but windows just
> won't
> > > let me use them.
> > > It drives me crazy, I can see it , but I can't force it to use the
> software.
> > >
> > > I contacted manufacturer support for the device first. And they said
> that
> > > the driver works and that it must be a windows problem.
> > > Also, I can't find ( Windows\Inf\Other folder ) either.
> > >
> > > I can't believe that I'm the only one that has run into this problem.
> > >
> > > Thanks again for your time.
> > >
> > > Lewis
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > "glee" <[email protected]> wrote in message
> > > news:%[email protected]...
> > > > I can't tell for sure what is going on but after you install the
> driver
> > > from the
> > > > disc, you should re-boot, then plug in the device after Windows
> starts.
> > > If the New
> > > > Hardware wizard pops up, instead of inserting the CD again and
> pointing it
> > > there, I
> > > > would just have Windows search for the driver on your system, since
> the
> > > driver has
> > > > already been installed. Point it to the Windows\System folder; if no
> > > joy, point it
> > > > to the Windows\Inf folder and Windows\Inf\Other folder. Windows
> should
> > > locate the
> > > > just-installed driver. You should not be pointing it to the CD.
> > > > If you still have the problem after that, I would contact support for
> the
> > > device
> > > > manufacturer.
> > > > --
> > > > Glen Ventura, MS MVP Shell/User, A+
> > > > http://dts-l.org/goodpost.htm
> > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > >
> > > >
> > > > "Lewis" <[email protected]> wrote in message
> > > > > I'm using USB 1.1 ports, I have four ports onboard, of which I use
> one
> > > for
> > > > > a add-on front mount card reader, that has four card slots and one
> USB
> > > 1.1
> > > > > port.
> > > > >
> > > > > I have tried all the ports and get the same results.
> > > > > I have tried the manufacturer's procedure many times.It calls for
> > > installing
> > > > > driver first. Then you plug in the mp3 player.
> > > > > But each time I do that, the new hardware wizard pops up and ask for
> > > driver
> > > > > for this device.
> > > > > I have canceled at times and there is a no go.
> > > > > And I have sent it to the driver file on the manufacturer's CD. And
> it
> > > says
> > > > > unable to locate driver.
> > > > >
> > > > > I really appreciate your help
> > > > >
> > > > >
> > > > > "glee" <[email protected]> wrote in message
> > > > > news:[email protected]...
> > > > > > It should be showing up there with its name, rather than as an
> unknown
> > > USB
> > > > > device.
> > > > > > It should also be appearing in Device Manager under the Disk
> Drives
> > > > > category. If it
> > > > > > does not, there is apparently a configuration problem, or the
> drivers
> > > are
> > > > > not
> > > > > > properly installed, or are defective. Have you tried uninstalling
> any
> > > > > > drivers/software that came with the player, and then reinstalling
> it
> > > > > following the
> > > > > > manufacturer's procedure, step by step?
> > > > > >
> > > > > > Are you plugging it into a USB 1.1 or a USB 2.0 port? Is the port
> an
> > > > > onboard port
> > > > > > directly attached to the motherboard, or is it an add-on PCI USB
> card?
> > > > > The fact
> > > > > > that the player works fine when you boot to WinXP shows that the
> > > hardware
> > > > > seems to
> > > > > > be OK, so it has to be in the configuration and/or the drivers for
> 98.
> > > > > >
> > > > > > Exactly what procedure did you follow to install it in Win98?
> > > > > > --
> > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > http://dts-l.org/goodpost.htm
> > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > >
> > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > I think it's showing up in my Generic USB Hub under the power
> tab as
> > > a
> > > > > > > Unknown USB Device.
> > > > > > > And there isn't anything I can do with it there.
> > > > > > > thanks
> > > > > > > Lewis
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > "glee" <[email protected]> wrote in message
> > > > > > > news:%[email protected]...
> > > > > > > > Right click on "My Computer" then left click on "Properties".
> > > > > > > > Click on the "Device Manager" tab, then double-click the "Disk
> > > drives"
> > > > > > > category to
> > > > > > > > expand it.
> > > > > > > > Look for your mp3 player model number in the list and
> double-click
> > > it
> > > > > (It
> > > > > > > will not
> > > > > > > > be one of the GENERIC drives).
> > > > > > > > Click on the "Settings" tab, click to put a check in the box
> for
> > > > > > > "Removable", click
> > > > > > > > "OK", then "Close", and reboot.
> > > > > > > >
> > > > > > > > Note: It may be listed under another category than "Disk
> Drives",
> > > so
> > > > > if
> > > > > > > not there,
> > > > > > > > check other categories.
> > > > > > > > --
> > > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > > >
> > > > > > > >
> > > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > > Thank you.
> > > > > > > > >
> > > > > > > > > Yes, it is a mp3 player and yes it is a USB device that is
> not
> > > > > being
> > > > > > > > > detected.
> > > > > > > > > I installed the driver for Win98se from the CD that came
> with
> > > the
> > > > > > > player.
> > > > > > > > > But when I plug it in to the USB port, the new hardware
> wizard
> > > pops
> > > > > up.
> > > > > > > > > I send it to the install CD/ driver file. Then it says it
> can't
> > > find
> > > > > > > > > software for this device.
> > > > > > > > >
> > > > > > > > > I can use it on a PC with XP without a problem.
> > > > > > > > >
> > > > > > > > > Thanks again
> > > > > > > > > Lewis
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > "glee" <[email protected]> wrote in message
> > > > > > > > > news:eLScoY\[email protected]...
> > > > > > > > > > Are we supposed to know what a "Rave.mp 256" is? From
> your
> > > > > > > description, I
> > > > > > > > > am
> > > > > > > > > > guessing it is some sort of USB device....perhaps an mp3
> > > player of
> > > > > > > some
> > > > > > > > > sort??
> > > > > > > > > >
> > > > > > > > > > What won't "boot up"? The computer "boots"....a USB
> device is
> > > > > > > "detected".
> > > > > > > > > Do you
> > > > > > > > > > mean the USB device is not being detected in My Computer?
> > > > > > > > > >
> > > > > > > > > > Read here:
> > > > > > > > > > http://dts-l.org/goodpost.htm and post back with more
> info.
> > > > > > > > > > --
> > > > > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > > >
> > > > > > > > > > > I have run the CD and installed win98se driver.
> > > > > > > > > > > But I can't get my pc to run the Rave.mp 256. I have
> tried
> > > > > > > everything I
> > > > > > > > > can
> > > > > > > > > > > think of. This USB port works fine, I use it for my
> Flash
> > > drives
> > > > > > > without
> > > > > > > > > a
> > > > > > > > > > > problem.The rave says " USB connected " it just won't
> > > boot-up at
> > > > > all
> > > > > > > in
> > > > > > > > > win
> > > > > > > > > > > explorer.
> > > > > > > > > > > Is there someone out there that may of had the problem?
> > > > > > > > > > > Is there a way to force the driver install?
> > > > > > > > > > >
> > > > > > > > > > > Thanks
> > > > > > > > > > > acer
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>
April 27, 2005 11:46:59 PM
Well I had a old PC in the garage. I started it up win98se, very
slow --64ram , 2gig HD.
I installed the cd software. Rebooted the pc plugged in the USB plug with
MP3 player attached .
Window popped up saying installing software for you device. It was called
several device names-- digital player, USB mass storage device. But it ended
up in the device manager as hard drive called RaveMp audio mp3 player. And
it shows up in the explorer as F: drive.
So I hooked it up to my newer PC. No Joy. This is Crazy
I'm not sure if I should use XP to update firmware. I will give it a try.
The driver installed into the System32 folder, so I thought that I would
copy them to the system folder to give it a hand. No joy either way.
thanks
Lewis
"glee" <[email protected]> wrote in message
news:u%[email protected]...
> I thought you said the device worked on WinXP. If so, you can update the
firmware
> there.
>
> I didn't mean to suggest you move driver files from one folder to
another.....only
> meant to state that on Win98SE, the drivers files should install
themselves to the
> System folder as opposed to the System32 folder.
> --
> Glen Ventura, MS MVP Shell/User, A+
> http://dts-l.org/goodpost.htm
> http://www.microsoft.com/communities/conduct/default.ms...
>
>
> "Lewis" <[email protected]> wrote in message
> > Well, I will have to find a win98se PC somewhere to try this device.
> >
> > But in the mean time, I went to --windows\system32 and copied the 2
driver
> > files that I could see.
> > I then put them in-- windows\system folder. And rebooted-- no joy.
> > So I left them there and removed the 2 files from system32 and
rebooted-- no
> > joy.
> >
> > There is a firmware update out for this USB device, do you think that
would
> > help?
> > But then I can't install it, if my mp3 doesn't boot up on this PC.
> >
> > Thanks Glee
> > Lewis
> >
> >
> >
> > "glee" <[email protected]> wrote in message
> > news:[email protected]...
> > > Right, you only can point the wizard (or any installer) to the folder
> > containing
> > > your drivers. It has to look for the type of file it wants, and must
see
> > the
> > > correct identifying info.......but, in Win9x, you would be pointing to
the
> > > Windows\System folder, not the System32 or System32\Drivers folder.
If
> > the wizard
> > > does not find what it wants in the System folder, point to the
Windows\Inf
> > folder.
> > > You may not have an Inf\Other sub-folder.....not all systems do.
> > > I am running out of ideas, if the ports work for everything else, and
the
> > device
> > > works on other operating systems. Can you try the device on another
> > Win98SE
> > > computer to see if it installs there? A friend of mine could not get
a
> > USB printer
> > > to install on his machine, and I got it to install on mine, but I had
to
> > hand-feed
> > > the installer the location of the .cat file to get it installed. I
then
> > went to his
> > > machine and installed the printer no problem, once I knew what the
issue
> > was.
> > > without trying the installation myself, it is hard to see where yours
> > might be
> > > failing. :-\
> > > --
> > > Glen Ventura, MS MVP Shell/User, A+
> > > http://dts-l.org/goodpost.htm
> > > http://www.microsoft.com/communities/conduct/default.ms...
> > >
> > >
> > > "Lewis" <[email protected]> wrote in message
> > > > Glee, thanks for your time.
> > > >
> > > > I have done everything you suggested. no joy!!!
> > > > It's crazy, because when I point to the windows\system32\drivers-
with
> > > > hardware wizard.
> > > > It just doesn't allow me to choose the drivers file, it will let
> > choose -
> > > > windows\system32.
> > > > However, it says, drivers can't be found.
> > > > But I can use explorer to see the driver software, but windows just
> > won't
> > > > let me use them.
> > > > It drives me crazy, I can see it , but I can't force it to use the
> > software.
> > > >
> > > > I contacted manufacturer support for the device first. And they
said
> > that
> > > > the driver works and that it must be a windows problem.
> > > > Also, I can't find ( Windows\Inf\Other folder ) either.
> > > >
> > > > I can't believe that I'm the only one that has run into this
problem.
> > > >
> > > > Thanks again for your time.
> > > >
> > > > Lewis
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > "glee" <[email protected]> wrote in message
> > > > news:%[email protected]...
> > > > > I can't tell for sure what is going on but after you install the
> > driver
> > > > from the
> > > > > disc, you should re-boot, then plug in the device after Windows
> > starts.
> > > > If the New
> > > > > Hardware wizard pops up, instead of inserting the CD again and
> > pointing it
> > > > there, I
> > > > > would just have Windows search for the driver on your system,
since
> > the
> > > > driver has
> > > > > already been installed. Point it to the Windows\System folder;
if no
> > > > joy, point it
> > > > > to the Windows\Inf folder and Windows\Inf\Other folder. Windows
> > should
> > > > locate the
> > > > > just-installed driver. You should not be pointing it to the CD.
> > > > > If you still have the problem after that, I would contact support
for
> > the
> > > > device
> > > > > manufacturer.
> > > > > --
> > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > http://dts-l.org/goodpost.htm
> > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > >
> > > > >
> > > > > "Lewis" <[email protected]> wrote in message
> > > > > > I'm using USB 1.1 ports, I have four ports onboard, of which I
use
> > one
> > > > for
> > > > > > a add-on front mount card reader, that has four card slots and
one
> > USB
> > > > 1.1
> > > > > > port.
> > > > > >
> > > > > > I have tried all the ports and get the same results.
> > > > > > I have tried the manufacturer's procedure many times.It calls
for
> > > > installing
> > > > > > driver first. Then you plug in the mp3 player.
> > > > > > But each time I do that, the new hardware wizard pops up and ask
for
> > > > driver
> > > > > > for this device.
> > > > > > I have canceled at times and there is a no go.
> > > > > > And I have sent it to the driver file on the manufacturer's CD.
And
> > it
> > > > says
> > > > > > unable to locate driver.
> > > > > >
> > > > > > I really appreciate your help
> > > > > >
> > > > > >
> > > > > > "glee" <[email protected]> wrote in message
> > > > > > news:[email protected]...
> > > > > > > It should be showing up there with its name, rather than as an
> > unknown
> > > > USB
> > > > > > device.
> > > > > > > It should also be appearing in Device Manager under the Disk
> > Drives
> > > > > > category. If it
> > > > > > > does not, there is apparently a configuration problem, or the
> > drivers
> > > > are
> > > > > > not
> > > > > > > properly installed, or are defective. Have you tried
uninstalling
> > any
> > > > > > > drivers/software that came with the player, and then
reinstalling
> > it
> > > > > > following the
> > > > > > > manufacturer's procedure, step by step?
> > > > > > >
> > > > > > > Are you plugging it into a USB 1.1 or a USB 2.0 port? Is the
port
> > an
> > > > > > onboard port
> > > > > > > directly attached to the motherboard, or is it an add-on PCI
USB
> > card?
> > > > > > The fact
> > > > > > > that the player works fine when you boot to WinXP shows that
the
> > > > hardware
> > > > > > seems to
> > > > > > > be OK, so it has to be in the configuration and/or the drivers
for
> > 98.
> > > > > > >
> > > > > > > Exactly what procedure did you follow to install it in Win98?
> > > > > > > --
> > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > >
> > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > I think it's showing up in my Generic USB Hub under the
power
> > tab as
> > > > a
> > > > > > > > Unknown USB Device.
> > > > > > > > And there isn't anything I can do with it there.
> > > > > > > > thanks
> > > > > > > > Lewis
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > "glee" <[email protected]> wrote in message
> > > > > > > > news:%[email protected]...
> > > > > > > > > Right click on "My Computer" then left click on
"Properties".
> > > > > > > > > Click on the "Device Manager" tab, then double-click the
"Disk
> > > > drives"
> > > > > > > > category to
> > > > > > > > > expand it.
> > > > > > > > > Look for your mp3 player model number in the list and
> > double-click
> > > > it
> > > > > > (It
> > > > > > > > will not
> > > > > > > > > be one of the GENERIC drives).
> > > > > > > > > Click on the "Settings" tab, click to put a check in the
box
> > for
> > > > > > > > "Removable", click
> > > > > > > > > "OK", then "Close", and reboot.
> > > > > > > > >
> > > > > > > > > Note: It may be listed under another category than "Disk
> > Drives",
> > > > so
> > > > > > if
> > > > > > > > not there,
> > > > > > > > > check other categories.
> > > > > > > > > --
> > > > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > >
> > > > > > > > > > Thank you.
> > > > > > > > > >
> > > > > > > > > > Yes, it is a mp3 player and yes it is a USB device that
is
> > not
> > > > > > being
> > > > > > > > > > detected.
> > > > > > > > > > I installed the driver for Win98se from the CD that came
> > with
> > > > the
> > > > > > > > player.
> > > > > > > > > > But when I plug it in to the USB port, the new hardware
> > wizard
> > > > pops
> > > > > > up.
> > > > > > > > > > I send it to the install CD/ driver file. Then it says
it
> > can't
> > > > find
> > > > > > > > > > software for this device.
> > > > > > > > > >
> > > > > > > > > > I can use it on a PC with XP without a problem.
> > > > > > > > > >
> > > > > > > > > > Thanks again
> > > > > > > > > > Lewis
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > "glee" <[email protected]> wrote in message
> > > > > > > > > > news:eLScoY\[email protected]...
> > > > > > > > > > > Are we supposed to know what a "Rave.mp 256" is? From
> > your
> > > > > > > > description, I
> > > > > > > > > > am
> > > > > > > > > > > guessing it is some sort of USB device....perhaps an
mp3
> > > > player of
> > > > > > > > some
> > > > > > > > > > sort??
> > > > > > > > > > >
> > > > > > > > > > > What won't "boot up"? The computer "boots"....a USB
> > device is
> > > > > > > > "detected".
> > > > > > > > > > Do you
> > > > > > > > > > > mean the USB device is not being detected in My
Computer?
> > > > > > > > > > >
> > > > > > > > > > > Read here:
> > > > > > > > > > > http://dts-l.org/goodpost.htm and post back with more
> > info.
> > > > > > > > > > > --
> > > > > > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > > > > >
http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > > > >
> > > > > > > > > > > > I have run the CD and installed win98se driver.
> > > > > > > > > > > > But I can't get my pc to run the Rave.mp 256. I have
> > tried
> > > > > > > > everything I
> > > > > > > > > > can
> > > > > > > > > > > > think of. This USB port works fine, I use it for my
> > Flash
> > > > drives
> > > > > > > > without
> > > > > > > > > > a
> > > > > > > > > > > > problem.The rave says " USB connected " it just
won't
> > > > boot-up at
> > > > > > all
> > > > > > > > in
> > > > > > > > > > win
> > > > > > > > > > > > explorer.
> > > > > > > > > > > > Is there someone out there that may of had the
problem?
> > > > > > > > > > > > Is there a way to force the driver install?
> > > > > > > > > > > >
> > > > > > > > > > > > Thanks
> > > > > > > > > > > > acer
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>
Anonymous
April 28, 2005 2:42:39 AM
Lewis, The fact that the device installed correctly on the old test machine tells
me there is nothing wrong with the device or the installer, and that you are
following the installation instructions correctly. It also indicates that upgrading
the firmware is probably *not* going to have any bearing on the problem on your main
Win98SE computer. There is obviously something amiss somewhere on your main Win98SE
machine, but unfortunately *where* that something is, is not clear. :-\
You said that other USB devices *are* working correctly on the problem computer, as
I recall from earlier replies. Try uninstalling all software related to the device,
then restart in Safe Mode, then open Device Manager and remove all entries there
that mention the device, if any exist in any categories. If there is an "Other"
category in DM, remove every item listed there. Look also in the Disk Drives
category in DM, and remove any and all entries that may exist for the device. If
there are any duplicate devices in that category, remove ALL devices in the
category. Same for Hard disk controllers category, CDROM category, and Universal
Serial Bus Controllers category....if any duplicates appear there, remove ALL listed
entries of that type. This must all be done in Safe Mode. When done, click
OK/Close, but before you restart, follow the instructions at the links below, to do
a clean boot. When you close msconfig to initiate the clean boot, you will then
restart in normal mode (Start> Shutdown> Restart).
After you restart doing the clean boot, Windows will re-detect any hardware you
removed from DM in Safe Mode. When that is done (reboot if prompted), install the
drivers for the problem device exactly as you did on the test machine from the
garage. Then, still in a clean boot startup configuration, reboot if prompted and
insert the device as you did on the test machine. See if this allows the device to
be installed correctly. When done, go back and set msconfig back from clean boot to
your normal startup configuration, and restart.
--
Glen Ventura, MS MVP Shell/User, A+
http://dts-l.org/goodpost.htm
http://www.microsoft.com/communities/conduct/default.ms...
> Well I had a old PC in the garage. I started it up win98se, very
> slow --64ram , 2gig HD.
>
> I installed the cd software. Rebooted the pc plugged in the USB plug with
> MP3 player attached .
> Window popped up saying installing software for you device. It was called
> several device names-- digital player, USB mass storage device. But it ended
> up in the device manager as hard drive called RaveMp audio mp3 player. And
> it shows up in the explorer as F: drive.
>
> So I hooked it up to my newer PC. No Joy. This is Crazy
>
> I'm not sure if I should use XP to update firmware. I will give it a try.
>
> The driver installed into the System32 folder, so I thought that I would
> copy them to the system folder to give it a hand. No joy either way.
>
> thanks
> Lewis
>
>
>
> "glee" <[email protected]> wrote in message
> news:u%[email protected]...
> > I thought you said the device worked on WinXP. If so, you can update the
> firmware
> > there.
> >
> > I didn't mean to suggest you move driver files from one folder to
> another.....only
> > meant to state that on Win98SE, the drivers files should install
> themselves to the
> > System folder as opposed to the System32 folder.
> > --
> > Glen Ventura, MS MVP Shell/User, A+
> > http://dts-l.org/goodpost.htm
> > http://www.microsoft.com/communities/conduct/default.ms...
> >
> >
> > "Lewis" <[email protected]> wrote in message
> > > Well, I will have to find a win98se PC somewhere to try this device.
> > >
> > > But in the mean time, I went to --windows\system32 and copied the 2
> driver
> > > files that I could see.
> > > I then put them in-- windows\system folder. And rebooted-- no joy.
> > > So I left them there and removed the 2 files from system32 and
> rebooted-- no
> > > joy.
> > >
> > > There is a firmware update out for this USB device, do you think that
> would
> > > help?
> > > But then I can't install it, if my mp3 doesn't boot up on this PC.
> > >
> > > Thanks Glee
> > > Lewis
> > >
> > >
> > >
> > > "glee" <[email protected]> wrote in message
> > > news:[email protected]...
> > > > Right, you only can point the wizard (or any installer) to the folder
> > > containing
> > > > your drivers. It has to look for the type of file it wants, and must
> see
> > > the
> > > > correct identifying info.......but, in Win9x, you would be pointing to
> the
> > > > Windows\System folder, not the System32 or System32\Drivers folder.
> If
> > > the wizard
> > > > does not find what it wants in the System folder, point to the
> Windows\Inf
> > > folder.
> > > > You may not have an Inf\Other sub-folder.....not all systems do.
> > > > I am running out of ideas, if the ports work for everything else, and
> the
> > > device
> > > > works on other operating systems. Can you try the device on another
> > > Win98SE
> > > > computer to see if it installs there? A friend of mine could not get
> a
> > > USB printer
> > > > to install on his machine, and I got it to install on mine, but I had
> to
> > > hand-feed
> > > > the installer the location of the .cat file to get it installed. I
> then
> > > went to his
> > > > machine and installed the printer no problem, once I knew what the
> issue
> > > was.
> > > > without trying the installation myself, it is hard to see where yours
> > > might be
> > > > failing. :-\
> > > > --
> > > > Glen Ventura, MS MVP Shell/User, A+
> > > > http://dts-l.org/goodpost.htm
> > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > >
> > > >
> > > > "Lewis" <[email protected]> wrote in message
> > > > > Glee, thanks for your time.
> > > > >
> > > > > I have done everything you suggested. no joy!!!
> > > > > It's crazy, because when I point to the windows\system32\drivers-
> with
> > > > > hardware wizard.
> > > > > It just doesn't allow me to choose the drivers file, it will let
> > > choose -
> > > > > windows\system32.
> > > > > However, it says, drivers can't be found.
> > > > > But I can use explorer to see the driver software, but windows just
> > > won't
> > > > > let me use them.
> > > > > It drives me crazy, I can see it , but I can't force it to use the
> > > software.
> > > > >
> > > > > I contacted manufacturer support for the device first. And they
> said
> > > that
> > > > > the driver works and that it must be a windows problem.
> > > > > Also, I can't find ( Windows\Inf\Other folder ) either.
> > > > >
> > > > > I can't believe that I'm the only one that has run into this
> problem.
> > > > >
> > > > > Thanks again for your time.
> > > > >
> > > > > Lewis
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > "glee" <[email protected]> wrote in message
> > > > > news:%[email protected]...
> > > > > > I can't tell for sure what is going on but after you install the
> > > driver
> > > > > from the
> > > > > > disc, you should re-boot, then plug in the device after Windows
> > > starts.
> > > > > If the New
> > > > > > Hardware wizard pops up, instead of inserting the CD again and
> > > pointing it
> > > > > there, I
> > > > > > would just have Windows search for the driver on your system,
> since
> > > the
> > > > > driver has
> > > > > > already been installed. Point it to the Windows\System folder;
> if no
> > > > > joy, point it
> > > > > > to the Windows\Inf folder and Windows\Inf\Other folder. Windows
> > > should
> > > > > locate the
> > > > > > just-installed driver. You should not be pointing it to the CD.
> > > > > > If you still have the problem after that, I would contact support
> for
> > > the
> > > > > device
> > > > > > manufacturer.
> > > > > > --
> > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > http://dts-l.org/goodpost.htm
> > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > >
> > > > > >
> > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > I'm using USB 1.1 ports, I have four ports onboard, of which I
> use
> > > one
> > > > > for
> > > > > > > a add-on front mount card reader, that has four card slots and
> one
> > > USB
> > > > > 1.1
> > > > > > > port.
> > > > > > >
> > > > > > > I have tried all the ports and get the same results.
> > > > > > > I have tried the manufacturer's procedure many times.It calls
> for
> > > > > installing
> > > > > > > driver first. Then you plug in the mp3 player.
> > > > > > > But each time I do that, the new hardware wizard pops up and ask
> for
> > > > > driver
> > > > > > > for this device.
> > > > > > > I have canceled at times and there is a no go.
> > > > > > > And I have sent it to the driver file on the manufacturer's CD.
> And
> > > it
> > > > > says
> > > > > > > unable to locate driver.
> > > > > > >
> > > > > > > I really appreciate your help
> > > > > > >
> > > > > > >
> > > > > > > "glee" <[email protected]> wrote in message
> > > > > > > news:[email protected]...
> > > > > > > > It should be showing up there with its name, rather than as an
> > > unknown
> > > > > USB
> > > > > > > device.
> > > > > > > > It should also be appearing in Device Manager under the Disk
> > > Drives
> > > > > > > category. If it
> > > > > > > > does not, there is apparently a configuration problem, or the
> > > drivers
> > > > > are
> > > > > > > not
> > > > > > > > properly installed, or are defective. Have you tried
> uninstalling
> > > any
> > > > > > > > drivers/software that came with the player, and then
> reinstalling
> > > it
> > > > > > > following the
> > > > > > > > manufacturer's procedure, step by step?
> > > > > > > >
> > > > > > > > Are you plugging it into a USB 1.1 or a USB 2.0 port? Is the
> port
> > > an
> > > > > > > onboard port
> > > > > > > > directly attached to the motherboard, or is it an add-on PCI
> USB
> > > card?
> > > > > > > The fact
> > > > > > > > that the player works fine when you boot to WinXP shows that
> the
> > > > > hardware
> > > > > > > seems to
> > > > > > > > be OK, so it has to be in the configuration and/or the drivers
> for
> > > 98.
> > > > > > > >
> > > > > > > > Exactly what procedure did you follow to install it in Win98?
> > > > > > > > --
> > > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > > >
> > > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > > I think it's showing up in my Generic USB Hub under the
> power
> > > tab as
> > > > > a
> > > > > > > > > Unknown USB Device.
> > > > > > > > > And there isn't anything I can do with it there.
> > > > > > > > > thanks
> > > > > > > > > Lewis
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > "glee" <[email protected]> wrote in message
> > > > > > > > > news:%[email protected]...
> > > > > > > > > > Right click on "My Computer" then left click on
> "Properties".
> > > > > > > > > > Click on the "Device Manager" tab, then double-click the
> "Disk
> > > > > drives"
> > > > > > > > > category to
> > > > > > > > > > expand it.
> > > > > > > > > > Look for your mp3 player model number in the list and
> > > double-click
> > > > > it
> > > > > > > (It
> > > > > > > > > will not
> > > > > > > > > > be one of the GENERIC drives).
> > > > > > > > > > Click on the "Settings" tab, click to put a check in the
> box
> > > for
> > > > > > > > > "Removable", click
> > > > > > > > > > "OK", then "Close", and reboot.
> > > > > > > > > >
> > > > > > > > > > Note: It may be listed under another category than "Disk
> > > Drives",
> > > > > so
> > > > > > > if
> > > > > > > > > not there,
> > > > > > > > > > check other categories.
> > > > > > > > > > --
> > > > > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > > > > http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > > >
> > > > > > > > > > > Thank you.
> > > > > > > > > > >
> > > > > > > > > > > Yes, it is a mp3 player and yes it is a USB device that
> is
> > > not
> > > > > > > being
> > > > > > > > > > > detected.
> > > > > > > > > > > I installed the driver for Win98se from the CD that came
> > > with
> > > > > the
> > > > > > > > > player.
> > > > > > > > > > > But when I plug it in to the USB port, the new hardware
> > > wizard
> > > > > pops
> > > > > > > up.
> > > > > > > > > > > I send it to the install CD/ driver file. Then it says
> it
> > > can't
> > > > > find
> > > > > > > > > > > software for this device.
> > > > > > > > > > >
> > > > > > > > > > > I can use it on a PC with XP without a problem.
> > > > > > > > > > >
> > > > > > > > > > > Thanks again
> > > > > > > > > > > Lewis
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > "glee" <[email protected]> wrote in message
> > > > > > > > > > > news:eLScoY\[email protected]...
> > > > > > > > > > > > Are we supposed to know what a "Rave.mp 256" is? From
> > > your
> > > > > > > > > description, I
> > > > > > > > > > > am
> > > > > > > > > > > > guessing it is some sort of USB device....perhaps an
> mp3
> > > > > player of
> > > > > > > > > some
> > > > > > > > > > > sort??
> > > > > > > > > > > >
> > > > > > > > > > > > What won't "boot up"? The computer "boots"....a USB
> > > device is
> > > > > > > > > "detected".
> > > > > > > > > > > Do you
> > > > > > > > > > > > mean the USB device is not being detected in My
> Computer?
> > > > > > > > > > > >
> > > > > > > > > > > > Read here:
> > > > > > > > > > > > http://dts-l.org/goodpost.htm and post back with more
> > > info.
> > > > > > > > > > > > --
> > > > > > > > > > > > Glen Ventura, MS MVP Shell/User, A+
> > > > > > > > > > > > http://dts-l.org/goodpost.htm
> > > > > > > > > > > >
> http://www.microsoft.com/communities/conduct/default.ms...
> > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > > > "Lewis" <[email protected]> wrote in message
> > > > > > > > > > > >
> > > > > > > > > > > > > I have run the CD and installed win98se driver.
> > > > > > > > > > > > > But I can't get my pc to run the Rave.mp 256. I have
> > > tried
> > > > > > > > > everything I
> > > > > > > > > > > can
> > > > > > > > > > > > > think of. This USB port works fine, I use it for my
> > > Flash
> > > > > drives
> > > > > > > > > without
> > > > > > > > > > > a
> > > > > > > > > > > > > problem.The rave says " USB connected " it just
> won't
> > > > > boot-up at
> > > > > > > all
> > > > > > > > > in
> > > > > > > > > > > win
> > > > > > > > > > > > > explorer.
> > > > > > > > > > > > > Is there someone out there that may of had the
> problem?
> > > > > > > > > > > > > Is there a way to force the driver install?
> > > > > > > > > > > > >
> > > > > > > > > > > > > Thanks
> > > > > > > > > > > > > acer
> > > > > > > > > > > > >
> > > > > > > > > > > > >
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
>
>
!
|
Basic College Mathematics (10th Edition)
The figure is known as a triangle. The perimeter is $5.8$ meters and the area is $1.575$ sq meters.
1. State the name of the figure: Triangle, since there are 3 sides. 2. Find the perimeter Let $P =$ the perimeter of the triangle $P = 2.1 + 2 + 1.7$ $P = 5.8$ m 3. Find the area Let $A =$ the area of the triangle $A = (base \times height) \div 2$ $A = (2.1 \times 1.5) \div 2$ $A = 3.15 \div 2$ $A = 1.575$ m$^{2}$
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## Journal of Differential Geometry
### Instanton counting and Donaldson invariants
#### Abstract
For a smooth projective toric surface we determine the Donaldson invariants and their wallcrossing in terms of the Nekrasov partition function. Using the solution of the Nekrasov conjecture [33, 38, 3] and its refinement [34], we apply this result to give a generating function for the wallcrossing of Donaldson invariants of good walls of simply connected projective surfaces with $b_+ = 1$ in terms of modular forms. This formula was proved earlier in [19] more generally for simply connected 4-manifolds with $b_+ = 1$, as-suming the Kotschick-Morgan conjecture, and it was also derived by physical arguments in [31].
#### Article information
Source
J. Differential Geom., Volume 80, Number 3 (2008), 343-390.
Dates
First available in Project Euclid: 7 November 2008
https://projecteuclid.org/euclid.jdg/1226090481
Digital Object Identifier
doi:10.4310/jdg/1226090481
Mathematical Reviews number (MathSciNet)
MR2472477
Zentralblatt MATH identifier
1172.57015
#### Citation
Göttsche, Lothar; Nakajima, Hiraku; Yoshioka, Kōta. Instanton counting and Donaldson invariants. J. Differential Geom. 80 (2008), no. 3, 343--390. doi:10.4310/jdg/1226090481. https://projecteuclid.org/euclid.jdg/1226090481
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## Peddapullaiah Sannuti
Professor
Education
B.E. (Hons), College of Engineering, Anantapur, India,1963
M. Tech., Indian Institute of Technology, Kharagpur, India, 1965
Ph.D., University of Illinois, Urbana, Illinois, 1968
Research Interests
Simultaneous internal and external stabilization of linear time-invariant systems in the presence of constraints is pursued. Internal stabilization is in the sense of Lyapunov while external stabilization is in the sense of L_p l_p stability with different variations, e.g. with or without finite gain, with fixed or arbitrary initial conditions, with or without bias. Concept of Lyapunov stability is well known. External stability seeks the controlled output be in L_p or l_p space for p = 1 to infinity whenever the external input or disturbance d of a system is in L_p or _p space. Several simultaneous external and internal stabilization problems are studied in depth, and appropriate adaptive feedback controllers that achieve the intended simultaneous external and internal stabilization are constructed whenever such problems are solvable.
Constraints can appear in many forms. They manifest in the form of imposing certain inputs or state variables be within certain bounded regions in their respective spaces. For instance, most nonlinear systems encountered in practice consist of linear systems and static nonlinear elements. Saturation is a ubiquitous non-linearity.
Physical quantities such as speed, acceleration, pressure, flow, current, voltage, and so on, are always limited to a finite range, and saturation non-linearities are therefore a ubiquitous feature of physical systems.
Awards and Recognitions
Obtained the best outgoing student award from College of Engineering, Anantapur, India, 1963
Elected to the grade of Fellow of IEEE with the citation, For contributions to the development of singular perturbation methods in systems and control', January 1988
Recent Textbooks Published
• A. Saberi A.Stoorvogel and P. Sannuti, Filtering Theory With Application to Fault Detection and Isolation, Birkhauser, 723 pages, 2007.
• A. Saberi A.Stoorvogel and P. Sannuti, Internal and External Stabilization of Linear Systems with Constraints -- Challenge of Constraints, Birkhauser , in print
Recent Journal Publications
X. Wang, A. Saberi, A. A. Stoorvogel, P. Sannuti, Simultaneous global external and internal stabilization of linear time-invariant discrete-time systems subject to actuator saturation''. To appear in Automatica, 2011, published online.
X. Wang, A. A. Stoorvogel, A. Saberi, P. Sannuti, Discrete-time $H_2$ and $H_\infty$ low-gain theory'', International Journal of Robust and Nonlinear Control, 2011 published online.
X. Wang, A. Saberi, A.A. Stoorvogel, S. Roy, P. Sannuti, Semi-global stabilization of discrete-time systems subject to non-right invertible constraints'', Int. J. Robust and Nonlinear Control,Vol. 20, Issue 11, pp. 1234-1254, July, 2010.
X. Wang, A. Saberi, A.A. Stoorvogel, S. Roy, P. Sannuti, Computation of the recoverable region and stabilization problem in the recoverable region for discrete-time systems'', Int. J. Control, Vol. 82, No. 10, 2009 pp. 1870-1881.
A. Saberi, A.A. Stoorvogel, P. Sannuti, Analysis, design, and performance limitations of H infinity optimal filtering in the presence of an additional input with known frequency'', Int. J. Robust and Nonlinear Control, Vol. 17, No. 16, 2007, pp. 1474-1488.
A. Saberi, A.A. Stoorvogel, P. Sannuti, `Connections between H2 optimal filters and unknown input observers -- Performance limitations of H2 optimal filtering'', Int. J. of Control, Vol. 79, No.2, February 2006, pp. 171-183.
Email:
sannuti @ rutgers.edu
Contact No.:
(848) 445-3127
Office:
CoRE 525
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## LSU Doctoral Dissertations
#### Identifier
etd-10312011-200227
#### Degree
Doctor of Philosophy (PhD)
Mathematics
Dissertation
#### Abstract
The classical Frobenius--Schur indicators for finite groups are character sums defined for any representation and any integer \$m\ge 2\$. In the familiar case \$m=2\$, the Frobenius--Schur indicator partitions the irreducible representations over the complex numbers into real, complex, and quaternionic representations. In recent years, several generalizations of these invariants have been introduced. Bump and Ginzburg in 2004, building on earlier work of Mackey from 1958, have defined versions of these indicators which are twisted by an automorphism of the group. In another direction, Linchenko and Montgomery in 2000 defined Frobenius--Schur indicators for finite dimensional semisimple Hopf algebras. In this dissertation, we construct twisted Frobenius--Schur indicators for semisimple Hopf algebras; these include all of the above indicators as special cases and have similar properties.
2011
#### Document Availability at the Time of Submission
Release the entire work immediately for access worldwide.
Sage, Daniel
COinS
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# prompthero /openjourney
Hello my fellow AI artists.
I am Muhammadreza Haghiri the founder of Open Cognitives and I observed something a little bit odd today. First of all, a person messaged me on LinkedIn and asked me about an interview about Open Journey. I immediately found out that it points to my old project and just out of curiosity I searched the link open-journey.github.io on Twitter and I found out a lot of people are just linking to this project of mine.
So I had to clarify it here.
Since I decided to make that project, prompthero's model wasn't called "openjourney" and this is why I chose that name. When they changed their name, I decided to go by the name Mann-E which was my model's original name. So this is the whole story. I totally forgot to remove that github page and it now redirects to Mann-E.
## Mann-E and OpenJourney
Okay, this is my favorite part of the story. Since I claimed I based my model on PromptHero's model I have to say it's true. Although there are differences in results (specially with different schedulers) but openjourney (specially version 2) is somehow a good base (or merger) for Mann-E.
## My personal opinion about PromptHero
What can I say? One of the most amazing teams in the field of AI Art.
Sincerely,
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# Setting up TEXINPUTS on MacOS Catalina
I use MacOS, LateXTools in Sublime Text as a TeX editor, and MacTeX as a TeX distribution. I store my macros in a folder named TEXINPUTS on Dropbox, and set up symlinks to the relevant location in my texmf tree.
`sudo ln -s /Users/nickriches/Dropbox/TEXINPUTS /usr/local/texlive/texmf-local/tex/latex`
This has worked fine under a variety of different MacOSes, but I am running into problems under MacOS Catalina. When I compile a document, it does not find the relevant .tex files stored in TEXINPUTS. This is very odd because when I do a system check with LaTeXTools, the location where the symlink has been created shows up as possible path for TEXINPUTS;
`:/usr/local/texlive/texmf-local/tex/latex`
So as far as I can see, TeX knows where to look. But it is still not finding the relevant .tex files. I've also tried setting the variable on the command line using EXPORT;
`export TEXINPUTS=.:/usr/local/texlive/texmf-local/tex/latex/\$TEXINPUTS`
which didn't work. Finally, I tried to enter the path in LaTeXTools builder settings;
`("env:" {"TEXINPUTS": ".:/usr/local/texlive/texmf-local/tex/latex/TEXINPUTS"}`
but for some reason, when I did this I lost the ability to compile any document.
Any pointers greatly welcomed!
• you want a trailing `:` in `("env:" {"TEXINPUTS": ".:/usr/local/texlive/texmf-local/tex/latex/TEXINPUTS"}` otherwise you not only add your directory, you remove all the standard places. similarly your export should have no`\$` and should have a `:` so `export TEXINPUTS=.:/usr/local/texlive/texmf-local/tex/latex/TEXINPUTS:` or if the issue is the symlink use `/Users/nickriches/Dropbox/TEXINPUTS` instead of `usr/local/texlive/texmf-local/tex/latex/TEXINPUTS` ? Jun 20, 2020 at 10:14
• I'm not sure what is happening that changed when you installed Catalina gut I know that Dropbox sometimes leads to problems.. Assuming you are using the TeX Live installed by the MacTeX installer why not put the link in your personal tree, `~/Library/texmf/tex/latex`? Jun 20, 2020 at 12:38
• Thanks for tip about colon at end of path, but adding it via "export" or in the LaTeXTools settings does not help. I didn't understand the issue about the symlink. I need to link from dropbox to relevant location in texmf. The path mentioned by Herb does not exist in MacOD Catalina Jun 20, 2020 at 16:30
• Okay, I have now done this. In the first place, the path I used to create the symlink was wrong! Secondly, I needed to place the path in the LaTeXTools settings file. Although the relevant path is appearing when LaTeXTools does a systems check for some reason it will not look in that location when compiling unless the path is added to the settings file. I was able to do this with help from David - I hadn't known it was necessary to add the colon at the end. I am not sure whether to put this as an answer myself, or maybe David can place his comment as an answer, and I can tick it. Jun 20, 2020 at 17:23
With MacTeX, TeX will look in `~/Library/texmf/tex` and its subdirectories for input files, so the simplest approach is to put the symlink under that directory.
Ahh... My path was wrong. It needed to end `TEXINPUTS/TEXINPUTS` as for some reason I had placed the genuine TEXINPUTS folder inside another one called `TEXINPUTS`.
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## Monday, March 31, 2008
### Monday Morning Algorithm 12: Boosted Subspace Pursuit using Re-weigthed Lp for Compressive Sensing
Today's algorithm is going to be a composition of two algorithms already implemented. When I implemented the algorithm of Wei Dai and Olgica Milenkovic on Subspace Pursuit (Monday Morning Algorithm 10), my implementation and my simple example would work most of the time but not all the time. I also noticed that the final solution was close to the expected solution. Then I remembered what Emmanuel Candes said in his lecture on re-weighted L1 (specifically, the last one entitled Applications, experiments and open problems) : find a solution close enough and then use re-weighted L1 to refine the solution further. Since the re-weighted Lp solution technique of Rick Chartrand and Wotao Yin has also been implemented (Monday Morning Algorithm 2), I rewrote a line into it so that it would take the solution of the subspace Pursuit as the initial guess of its solution (instead of the L2 solution as is done in the original algorithm). By running SPtrial of the initial subspace pursuit implementation one may get this result:
The solution is wrong but not that wrong. By using this solution as a guess into the re-weighted Lp algorithm, one eventually obtains:
function x = lp_re1(A,y,p,x0)
%
% lp-Reweighted Least Squares Problem Solver
% Algorithm implementing an approach suggested in
% "Iteratively Reweighted Algorithms for Compressive Sensing"
% by Rick Chartrand and Wotao Yin
% Algorithm implemented as featured in:
% http://math.lanl.gov/Research/Publications/Docs/chartrand-2008-iteratively.pdf
%
%
% lp_re solves problems of the following form:
% minimize ||x||_p
%
% subject to A*x = y
%
% where A and y are problem data and x is variable (described below).
%
% CALLING SEQUENCES
% [x] = lp_re1(A,y,p,x0);
%
% INPUT
% A : mxn matrix; input data. columns correspond to features.
%
% m : number of measurements ( or rows) of A
% n : dimension of ambient space (or columns) of A
%
% y : vector of dimension m; result.
%
% p : norm order; p = 1 is l1 norm
%
% x0 : guess for x, vector of size n
%
% OUTPUT
% x : vector of vector n; initial unknown
%
% USAGE EXAMPLES
% x = lp_re(A,y,p,x0);
%
% AUTHOR Igor Carron
% UPDATE ver. 0.1, Feb 7 2008
%
% Creative Commons Licence
% http://en.wikipedia.org/wiki/Creative_Commons
%
epsilon = 1
% u_0 is a guess given to the subroutine
u_0 = x0;
u_old = u_0;
j=0;
while epsilon > 10^(-8)
j;
epsilon;
j = j + 1
w = (u_old.^(2) + epsilon).^(p/2-1);
v = 1./w;
Q_n = diag(v,0);
tu = inv(A*Q_n*A');
u_new = Q_n * A' * tu * y;
if lt(norm(u_new - u_old,2),epsilon^(1/2)/100)
epsilon = epsilon /10;
end
u_old = u_new;
end
x=u_new;
This is obviously a toy example that can be started by running SP1trial. In larger cases, one needs to pay attention to the issue Joel Tropp mentioned earlier (fast multiply) as re_lp1 is real slow otherwise. The code and example can be found on the Monday Morning Algorithm page.
Credit:NASA/JPL/GSFC/SwRI/SSI, Enceladus Heat map as seen by Cassini 19 days ago.
### Compressed Sensing: Who are you ? and the poll result.
This blog was initially there so I would be able to put those nagging ideas in a written form somewhere. It has evolved to be a little more than that in many ways but the most profound change recently has been a focus on Compressed Sensing or Compressive Sensing. With that in mind and after a year in that mode, here are some of the statistics of the blog that might account for how a nascent subject is faring on the interwebs.
First things first, there have been about 170 posts on the subject in the past year. More recent entries provide the abstract of the new papers because I believe that in this day and age, unless there is a location that does that, the papers won't get read. It's a shame to say this but my own experience suggests that unless you have been hooked on by an abstract and maybe some graphs, it is very difficult to get people to read your stuff. No matter how good the paper is. The reason ? Everybody is busy and at the same time drowning under a pile of things to do. As one of the reader mentioned, each entry provides a good read when commuting. The blog serves the purpose of getting people's attention on every new paper but it also provides for Google a way to index it. While Mark Davenport and other folks at Rice do an excellent job at gathering new papers on the subject when it is submitted to them, sometimes a more pro-active means is necessary to find new papers on the subject. Mark also does a great job at adding other subjects areas that have, in retrospect, great relevance to the subject.
Eventually, I am still bewildered at the different communities that contribute to the subject. The side effect of this mix is that the community sees itself as loosely tied both in terms of subject areas treated and geographically (as witnessed from the heat map above.) The figure below provides actual hits and page views to the blog. It shows a steady increase of the readership mostly through search requests from Google. This March was the first time the blog saw more than 4,000 page views in a month. This is not a Slashdot effect as I have seen before but rather a growing trend over several months.
Feedburner also provides page statistics, and the 160 average daily visit squares well with the 4,000 visit/monthly given above. That 160 number is also well correlated with Google analytics numbers shown below.
But the statistics I like the most is this one: In the past week, about 20 percent of the people visiting the blog directly, ended up spending more than 5 minutes on the blog. Five minutes is a loooooong time......
Now with regards to the poll. Answer 2 "Compressed Sensing: A Paradigm shift in sensing, don't be the last one to say DUH" is the one with the most hits. It looks like going for the Simpsons is always a winner.
One more thing, the ads ran for 18 days and the words "compressed sensing" and "compressive sensing" seemed to have been searched on Google about 1,600 times or about 88 times a day (number of impressions) during that time period.
And remember, this statistic 50/160/88 squarely goes against George Constanza's routine: It's not me, It's you :-)
## Friday, March 28, 2008
### Compressed Sensing: A Lecture on the Convergence of CoSaMP
Joel Tropp gave an excellent talk today at IHP. For two hours, he pretty much gave the proofs of the convergence of CoSaMP, a work he has done with Deanna Needell.
Besides the talk, here are some excerpts that I found interesting. He mentioned that Emmanuel Candes is still getting reviews saying "Everyone knows this is impossible" when talking about finding the solution of an under-determined system when the solution is sparse. I should probably include this in the adwords ads (please take the poll). It also really points to the need to do a better job spreading that word.
One of the reason, Joel is partial to the Partial Fourier Transform lies in three reasons:
• It is technologically relevant: some technology like MRI directly access the Fourier domain
• The FFT is a fast matrix-vector multiply (see previous discussion) and finally,
• There is a low storage requirement for that matrix (as opposed to Gaussian ensembles for instance)
Finally, when the Conjugate gradient error estimate is included in the general error treatment for the convergence of CoSaMP ( see previous discussion) it looks as though, one requires on the order of three iterations per use of the Conjugate Gradient to get a satisfactory convergence without polluting CoSaMP.
Joel also seems to think that RIP is not the reason why CoSaMP works and that there maybe a more generic reason but that it has not been found yet (my words). The proof of the convergence of CoSaMP relies heavily on RIP but maybe, this is my guess, better bounds independent of RIP could be found in the future.
The organizers did a good job of inviting him over.
On a different note Irina Rish seems top think that taping the workshop is a good idea. We'll see.
### Call for Papers: Sparse Optimization and Variable Selection
Here is a workshop related to many of the themes mentioned on Nuit Blanche. It is an ICML/UAI/COLT 2008 workshop on Sparse Optimization and Variable Selection. There are 38 days before the deadline submission on May 5. From the site:
Call for Papers
Please submit an extended abstract (1 to 3 pages in two-column ICML format) to the workshop email address [email protected]. The abstract should include author names, affiliations, and contact information. Papers will be reviewed by at least 3 members of the program committee.
Overview
Variable selection is an important issue in many applications of machine learning and statistics where the main objective is discovering predictive patterns in data that would enhance our understanding of underlying physical, biological and other natural processes, beyond just building accurate 'black-box' predictors. Common examples include biomarker selection in biological applications [1], finding brain areas predictive about 'brain states' based on fMRI data [2], and identifying network bottlenecks best explaining end-to-end performance [3,4], just to name a few.
Recent years have witnessed a flurry of research on algorithms and theory for variable selection and estimation involving sparsity constraints. Various types of convex relaxation, particularly L1-regularization, have proven very effective: examples include the LASSO [5], boosted LASSO [6], Elastic Net [1], L1-regularized GLMs [7], sparse classifiers such as sparse (1-norm) SVM [8,9], as well as sparse dimensionality reduction methods (e.g. sparse component analysis [10], and particularly sparse PCA [11,12] and sparse NMF [13,14]). Applications of these methods are wide-ranging, including computational biology, neuroscience, graphical model selection [15], and the rapidly growing area of compressed sensing [16-19]. Theoretical work has provided some conditions when various relaxation methods are capable of recovering an underlying sparse signal, provided bounds on sample complexity, and investigated trade-offs between different choices of design matrix properties that guarantee good performance.
We would like to invite researchers working on the methodology, theory and applications of sparse models and selection methods to share their experiences and insights into both the basic properties of the methods, and the properties of the application domains that make particular methods more (or less) suitable. We hope to further explore connections between variable selection and related areas such as dimensionality reduction, optimization and compressed sensing.
Suggested Topics
We would welcome submissions on various aspects of sparsity in machine-learning,from theoretical results to novel algorithms and interesting applications. Questions of interest include, but are not limited to:
* Does variable selection provide a meaningful interpretation of interest to domain experts?
* What method (e.g., combination of regularizers) is best-suited for a particular application and why?
* How robust is the method with respect to various type of noise in the data?
* What are the theoretical guarantees on the reconstruction ability of the method? consistency? sample complexity?
Comparison of different variable selection and dimensionality reduction methods with respect to their accuracy, robustness, and interpretability is encouraged.
I need to ask if some recordings of the tutorials will be made, the same way IMA did for the course on Compressed Sensing last year.
### Compressed Sensing: A Poll.
In the past three weeks, I have toyed with the Google's Adwords system to gauge the general interest in Compressed Sensing or Compressive Sensing. The field is very small, as expected, so the keywords are very likely to show up every time somebody hits on these keywords (please don't click it kills me :-)). There is also the ability to customize different banners. The poll question is: As of today (no need to click on the ad to change the percentage) which Ad listed above got the most hits ? I'll give the answer on Monday.
## Thursday, March 27, 2008
### Compressed Sensing: Chirp sensing codes a new deterministic measurement tool and Image Processing with Non-local Spectral Bases
A new update from the Rice Repository, where we have yet another deterministic construction of a measurement matrix by Lorne Applebaum, Stephen Howard, Stephen Searle and Robert Calderbank in Chirp sensing codes: Deterministic compressed sensing measurements for fast recovery. The abstract reads:
Compressed sensing is a novel technique to acquire sparse signals with few measurements. Normally, compressed sensing uses random projections as measurements. Here we design deterministic measurements and an algorithm to accomplish signal recovery with computational efficiently. A measurement matrix is designed with chirp sequences forming the columns. Chirps are used since an efficient method using FFTs can recover the parameters of a small superposition. We show empirically that this type of matrix is valid as compressed sensing measurements. This is done by a comparison with random projections and a modified reduced isometry property. Further, by implementing our algorithm, simulations show successful recovery of signals with sparsity levels similar to those possible by Matching Pursuit with random measurements. For sufficiently sparse signals, our algorithm recovers the signal with computational complexity O(K logK) for K measurements. This is a significant improvement over existing algorithms.
Let us note the use of the statistics of the eigenvalues of the Gram matrices (made from the measurement matrix) "rather than a formulation of their bound" in oder to express some statement on the RIP constants. The measurement matrix is made up of a combination of chirps. The paper also prescribes a reconstruction technique as well. The reconstruction complexity is expected to scale as O(MK logK). From the conclusion:
This paper can serve as a preliminary read to [11] for those less familiar with Reed-Muller codes. Regardless of the above limitation, chirp sensing codes excel as method for fast signal recovery with compressed sensing.
In a different closely related area, we have an investigation of Image Processing with Non-local Spectral Bases by Gabriel Peyré. The abstract reads:
This article studies regularization schemes that are defined using a lifting of the image pixels in a high dimensional space. For some specific classes of geometric images, this discrete set of points is sampled along a low dimensional smooth manifold. The construction of differential operators on this lifted space allows one to compute PDE flows and perform variational optimizations. All these schemes lead to regularizations that exploit the manifold structure of the lifted image. Depending on the specific definition of the lifting, one recovers several well-known semi-local and non-local denoising algorithms that can be interpreted as local estimators over a semilocal or a non-local manifold. This framework also allows one to define thresholding operators in adapted orthogonal bases. These bases are eigenvectors of the discrete Laplacian on a manifold adapted to the geometry of the image. Numerical results compare the efficiency of PDE flows, energy minimizations and thresholdings in the semi-local and non-local settings. The superiority of the non-local computations is studied through the performance of non-linear approximation in orthogonal bases.
It is a long paper worth reading as it tries to connect traditional techniques to newer ones like diffusion methods that have also been used for dimension reduction and by the same token the building of sparse dictionaries.
The main contribution of this paper is that it bridges the gap between adaptive filtering methods and thresholding in adapted orthogonal bases. In order to do so, it reviews recent approaches to semi-local and non-local adaptive filtering of images. The use of thresholding in non-local orthogonal bases is suggested in [50] and we further study the properties of such thresholdings. The connexions with more traditional wavelet-based and total variation algorithms is made clear together with a study of the pros and cons of each method.
## Wednesday, March 26, 2008
### Compressed Sensing: Combinatorial Explosion of Dictionaries-Measurements-Solvers, Can Sparco Help ?
The current undertakings summarized in the big picture document show a large diversity of approaches when performing Compressed Sensing or Compressive Sensing. And yet, if one were new to the field, what would be required to design a specific means for acquiring compressed samples ?
One would first have to know the domain specific characteristics of the dataset, that is we take for granted that it is understood that the domain specific signals are sparse in some basis. Given that information, one would then perform some type of trade studies on how the processes for measurement and reconstruction are eventually yielding satisfactory data. But here lies a problem that has also plagued wavelets a decade ago: too much choice and a predisposition to always deal with 1-d information.
On the measurement side, we have about 26 ways of performing compressed measurements. On the reconstruction side, we have 17 different algorithms. I am not saying they are a good fit to one another, but we are facing, today, a potential of about 442 different implementations for the same problem. Let us not even talk about the fact that several dictionaries of sparse functions could be used in the reconstruction of one test case. Obviously, a hardware solution will remove many of the measurement and reconstruction schemes either based on engineering trade-offs or because of the nature of the signal. Yet, it would seem that a more automated evaluation of the phase space of possibilities might be helped by a general framework like the one implemented in Sparco. The richness of potential combinations for a specific signal type seem painless to implement. After I mentioned some installation issues, Michael P. Friedlander and Ewout van den Berg have written some work-around and it now works flawlessly after a clean install. They just released that version (v.1.1.3) on the Sparco website. They are also looking for feedbacks and users.
Michael and Ewout mentioned that they wanted Sparco to be relatively agnostic in terms of the solver used, but it would seem to me that there should also be a similar concern with regards to measurement means. In particular, one should probably think of a way to add measurements and solvers at once so that it can be run directly within Sparco.
Credit: NASA/JPL/Space Science Institute, Janus one of Saturn's moon, photograph released today.
## Tuesday, March 25, 2008
### Wired on Face Recognition and Sparse Representation: An Introduction to Compressed Sensing ?
Wired has a report on the excellent work of Allen Yang, John Wright and Yi Ma mentioned earlier (a technique we implemented in one of the Monday Morning Algorithm.) For those readers coming to this site, please note that a similar type of effort has been undertaken by Jort Gemmeke for voice (Using sparse representations for missing data imputation in noise robust speech recognition). For those of you that want to know more from the description given in the Wired article:
The secret sauce in Yang's new method is a mathematical technique for solving linear equations with sparse entries called, appropriately enough, sparse representation
The "solving linear equation with sparse entries" technique is intimately linked to a subject called compressed sensing or compressive sensing this blog is covering. The same technique is used to implement the astounding single pixel camera at Rice. In short, solving this type of system does not involve solving a least-square problem but involves the use of "weirder" techniques that have only recently been unveiled by people like the recent Fields Medalist Terry Tao, Emmanuel Candes, Justin Romberg, David Donoho and many others. A technical view of the rapidly evolving field on the subject can be found here. Reference papers can be found here.
Credit: NASA/JPL/Space Science Institute, A photograph of Thetys, Titan and Saturn released yesterday.
### Compressed Sensing: Computation and Relaxation of Conditions for Equivalence between l1 and l0 Minimization, Sparco remark and an addendum.
Here is an update on Computation and Relaxation of Conditions for Equivalence between l1 and l0 Minimization by Allen Yang, John Wright and Yi Ma. The abstract reads
In this paper, we investigate the exact conditions under which the l1 and l0 minimizations arising in the context of sparse error correction or sparse signal reconstruction are equivalent. We present a much simplified condition for verifying equivalence, which leads to a provably correct algorithm that computes the exact sparsity of the error or the signal needed to ensure equivalence. In the case when the encoding matrix is imbalanced, we show how an optimal diagonal rescaling matrix can be computed via linear programming, so that the rescaled system enjoys the widest possible equivalence.
As stated in this interesting paper:
The main contribution of this paper is a simple, novel algorithm for determining when l1-l0 equivalence holds in a given linear system of equations.
I wonder if this type of algorithm should not be included in Sparco. While Sparco wants to be agnostic with regards to the reconstruction solver (so that everyone can use theirs), measurement matrices and other algorithm checking UUP and/or l0-l1 correspondance might add some additional value to the software.
There is also an addendum to the published version of a paper we covered before (Single Pixel Imaging via Compressive Sampling). It reads:
`Erratum for "Single Pixel Imaging via Compressive Sampling"In page 91, paragraph 5 of the appendix, where the paper reads"...and so each measurement follows a Poisson distribution with mean andvariance (PT/2) for BS and (PTM/2N) for CS."it should read"...and so each measurement follows a Poisson distribution with mean andvariance (PT/2) for BS and (PTN/2M) for CS."`
Image courtesy: NASA/JPL-Caltech/Cornell/ASU/Texas A&M/Navigation camera, Opportunity rover camera watching Martian clouds.
## Monday, March 24, 2008
### Monday Morning Algorithm 11: Sparse Measurement Matrix using Scrambled Block Hadamard Ensemble
In a previous entry, we discovered the paper by Lu Gan, Thong Do and Trac Tran that provides us with a compact measurement matrix as described in Fast compressive imaging using scrambled block Hadamard ensemble. We are going to implement this sparse measurement matrix as we have previously done with a similar entry in the Monday Morning Algorithm series. This measurement matrix is a cornerstone in the field of Compressed Sensing. If you don't know about Compressed Sensing, you may want to check this out. As usual all errors are mine and if you find a mistake in the implementation, please let me know. If you also know how to quietly do evals with matlab I am also a taker.
function [wfinal]=sbhe(k,hd,mt)
%
% Function implementing measurement matrix as given in
% "Fast compressive imaging using scrambled block Hadamard ensemble."
% by Lu Gan, Thong Do and Trac Tran
%
% Written by Igor Carron.
%
% Input:
% k : number of hadamard matrix blocks
% hd: size of Hadamard matrix (needs to be divisible by 2)
% mt: number of columns of wfinal
% Output:
% wfinal: matrix with k*nd columns and mt rows
%
% k=10;
% hd = 32;
% mt = 30;
ntotal = hd * k;
st1='';
for i=1:k-1
st1 = strcat(st1,'wh,');
end
st1= strcat(st1,'wh');
eval(['w = blkdiag(' st1 ')']);
u = randperm(ntotal);
for ii=1:ntotal
wnew(:,ii)=w(:,u(ii));
end
%figure(1)
%spy(w)
%figure(2)
%spy(wnew)
vv = [];
while size(vv,1)~=mt
v2 = cat(2,vv,round(1+rand(mt,1)*(ntotal-1)));
vv = unique(v2);
end
m = size(vv,1);
for j=1:m
wfinal(j,:) = wnew(vv(j),:);
end
%spy(wfinal)
Credit Photo: ESA/ MPS/DLR/IDA, Venus’s atmosphere, taken by the Venus Monitoring Camera (VMC) during Venus Express orbit number 458 on 23 July 2007.
## Saturday, March 22, 2008
### The story behind the Dantzig Selector paper and an Anagram
Terry Tao provides a nice overview of the story behind the ideas and results of “The Dantzig selector: Statistical estimation when p is much larger than n" a paper he published with Emmanuel Candés. Publishing the paper was one thing, but as he explains:
After accepting our paper, the Annals of Statistics took the (somewhat uncommon) step of soliciting responses to the paper from various experts in the field, and then soliciting a rejoinder to these responses from Emmanuel and I. Recently, the Annals posted these responses and rejoinder on the arXiv.
I'd say, this is indeed rather unusual even in the Applied Sciences. In my view, this move only attests to importance of the work. The blog entry is here.
On a lighter note, Laurent Duval proposes a witty anagram for Compressive sensing: Processing Vein Mess.
### Compressed Sensing: Reconstructing sparse signals from their zero crossings
In looking at the updates on the Rice site, I nearly missed this one from Petros Boufounos, Richard Baraniuk, Reconstructing sparse signals from their zero crossings. The abstract reads:
Classical sampling records the signal level at pre-determined time instances, usually uniformly spaced. An alternative implicit sampling model is to record the timing of pre-determined level crossings. Thus the signal dictates the sampling times but not the sampling levels. Logan’s theorem provides sufficient conditions for a signal to be recoverable, within a scaling factor, from only the timing of its zero crossings. Unfortunately, recovery from noisy observations of the timings is not robust and usually fails to reproduce the original signal. To make the reconstruction robust this paper introduces the additional assumption that the signal is sparse in some basis. We reformulate the reconstruction problem as a minimization of a sparsity inducing cost function on the unit sphere and provide an algorithm to compute the solution. While the problem is not convex, simulation studies indicate that the algorithm converges in typical cases and produces the correct solution with very high probability.
In the conclusion they mention:
In summary, formulating the problem of sparse signal reconstruction from zero crossings as a sparsity inducing optimization on the unit sphere stabilizes the reconstruction. This formulation can be extended beyond Fourier sparsity to accommodate other sparsity bases by appropriately modifying the sampling operator $\Phi^T$ but the performance of such a modification needs to be evaluated. Furthermore, although the algorithm described provides the solution with high empirical probability, further research on reconstruction algorithms and their performance is necessary.
This is not unlike the result of Yves Meyer and Basarab Matei where using an additional constraint on the optimization (in the case of Meyer and Basarab, it's really a theorem), one seems to be able to retrieve full signal (in the case of Meyer and Basarab, it is proven).
### Compressed Sensing: Fast compressive imaging using scrambled block Hadamard ensemble, Compressed sensing for surface metrology
New updates from the Rice repository:
Lu Gan, Thong Do, Trac Tran that seem to provide us with a compact measurement matrix with Fast compressive imaging using scrambled block Hadamard ensemble
With the advent of a single-pixel camera, compressive imaging applications have gained wide interests. However, the design of efficient measurement basis in such a system remains as a challenging problem. In this paper, we propose a highly sparse and fast sampling operator based on the scrambled block Hadamard ensemble. Despite its simplicity, the proposed measurement operator offers universality and requires a near-optimal number of samples for perfect reconstruction. Moreover, it can be easily implemented in the optical domain thanks to its integer-valued elements. Several numerical experiments show that its imaging performance is comparable to that of the dense, floating-coefficient scrambled Fourier ensemble at much lower implementation cost.
The conclusion is attractive where one would to implement it right away:
This paper has proposed the scrambled block Hadamard ensemble (SBHE) as a new sampling operator for compressive imaging applications. The SBHE is highly sparse and fast computable along with optical-domain friendly implementations. Both theoretical analysis and numerical simulation results have been presented to demonstrate the promising potential of the SBHE. In particular, we showed that a highly sparse SBHE can produce similar compressive imaging performance as that of a dense scrambled Fourier ensemble at much lower implementation cost.
In a different area Jianwei Ma provides a new fascinating reason for using Compressed Sensing in Compressed sensing for surface metrology.
Surface metrology is the science of measuring small-scale features on surfaces. In this paper we introduce compressed sensing theory into the surface metrology to reduce data acquisition. We describe that the compressed sensing is naturally fit to surface analysis. A recovery algorithm is proposed for scratched and textural surfaces by solving a convex optimal problem with sparse constrained by curvelet transform and wave atom transform. One can stably recover compressible surfaces from a random incomplete and inaccurate measurements, i.e., far fewer measurements than traditional methods use while does not obey the Shannon sampling theorem. This is very significant for measurements limited by physical and physiological constraints, or extremely expensive. The compressed measurement essentially shift measurement cost to computational cost of off-line nonlinear recovery. Thus we call this method as compressed metrology or computational metrology. Different from traditional measuring method, it directly senses the geometric and structural features instead of single pixel's information. By combining the idea of sampling, sparsity and compression, the compressed measurement indicates an new acquisition protocol and leads to building simpler and cheaper measurement instruments. Experiments on engineering and bioengineering surfaces demonstrate good performances of the proposed method.
Creidt Photo: Darvaza flaming crater in Turkmenistan Via Fogonazos.
## Friday, March 21, 2008
### Compressed Sensing: SPARCO is your friend.
In October, I mentioned the birth of SPARCO ( by Ewout van den Berg, Michael P. Friedlander, Gilles Hennenfent, Felix J. Herrmann, Rayan Saab, and Ozgur Yilmaz) a new framework where one could try his/her reconstruction technique and follow the reproducible research guidelines. The software has grown to be a little bit more since then it seems and now it provides a good platform for learning about Compressed Sensing or Compressive Sensing by running different cases and have direct access to the sometime strange measurement matrices found in the literature. Not unlike Wavelab, SPARCO provides a set of problem example that have been worked out and published. All these problem sets are nicely featured in this page. Not only does it list the problem but it also provides the reader with the Measurement matrix type and the Sparsity matrix as well. This is is a nice touch.
Of further interest is the ability to use complex operations that enable to build measurement or sparsity operators as well as meta-operators. A lot has gone into this and the authors should be thanked for it.
The technical report provides ample information on how these examples and operators work. In the documentation, one can see how to rapidly prototype a new case with SPARCO operators. I have had some problems running some of the examples because of functions of the Rice Wavelet Toolbox not getting the right parameters.
Besides this minor problem, SPARCO seems a solid platform that will grow by including other dictionaries, measurement matrices and reconstruction operators to the satisfaction of the whole community. Eventually, we'll need operators to bring the dictionaries found from tensor factorizations into 2-D that SPARCO can handle.
## Wednesday, March 19, 2008
### Computing Nonnegative Tensor Factorizations, Arthur C. Clarke and Multi-Aperture Lenses
If you are lost because your data isn't 2-D, and you want a sparse decomposition of your dataset, Michael Friedlander and Kathrin Hatz just released Computing nonnegative tensor factorizations. The abstract reads:
Nonnegative tensor factorization (NTF) is a technique for computing a parts-based representation of high-dimensional data. NTF excels at exposing latent structures in datasets, and at finding good low-rank approximations to the data. We describe an approach for computing the NTF of a dataset that relies only on iterative linear-algebra techniques and that is comparable in cost to the nonnegative matrix factorization. (The better-known nonnegative matrix factorization is a special case of NTF and is also handled by our implementation.) Some important features of our implementation include mechanisms for encouraging sparse factors and for ensuring that they are equilibrated in norm. The complete Matlab software package is available under the GPL license.
The Matlab code is available here. This is a tool that enables one to build dictionaries from data not necessarily in dimension 2. It has its place in the sparse dictionaries section of the big picture on Compressive Sensing.
Arthur Clarke (who just passed away), the man publicizing the idea of geostationary satellites, once said, there are three phases to a great idea:
The first phase is when people tell you it’s a crazy idea, it will never work; the second phase is when people say, it might work, but it’s not worth doing; and the third phase is when people say, I told you that was a great idea all along!
Projecting on a few random bases and getting the full signal back from solving a linear programming step, that'll never work....
Following up on the evaluation of the current imaging systems that are tweaked to provide additional information, here is a multi-aperture system at Stanford using 12,616 lenses.
The 3-D information is extracted from the stereographic view projected in different parts of the CMOS. One should also note the statement that one now needs about 10 MP in order to provide a 3 MP spatial resolution. Much of that hardware engineering implementation is focused on not mixing different rays of light and one wonders if mixing them as done in Compressive Sensing would not be simpler. The difficulty of the Compressed Sensing approach resides in that most photographic customers do not want a "computational reconstruction" if that process requires a computer.
So the real question is: is there a customer base that is OK with the computational reconstruction step because it brings additional information (in hyperspectral mode or in a time mode) that they really care about?
Photo Credit: NASA/JPL, 36 locations found by the Mars Odyssey orbiter (named in Honor of Arthur Clarke and his book 2001: A Space Odyssey) and selected by NASA to be the first regions where humans (future Martians) will set foot on Mars when they go there.
## Tuesday, March 18, 2008
### Compressed Sensing: Subspace Pursuit Code, Fast Matrix-Vector multiply is crucial for Fast Greedy Algorithms, Partial FMM or MRP
Wei Dai kindly provided me with the original code used in the paper on Subspace Pursuit and asked me to put it on this site. In this day and age, I think people expect students and post-docs to set up a webpage. For instance, Google Pages (create a Google account first) provides an easy way of creating a webpage (through page creator) and allows one to own a nice placeholder, especially when one is likely to move into another position in the future. I generally link directly to the website of the people who have written papers on Compressed Sensing. I am always surprised when I cannot find any trace of somebody on the net, especially when that somebody has published and do research at a U.S. University. If you feel I did not link to your site, or did so but to the wrong site, please let me know, I'll correct it.
Following yesterday's entry on CoSaMP: Iterative signal recovery from incomplete and inaccurate samples, Joel Tropp sent me an e-mail on an issue I totally missed and misreported:
"... Thanks for noting CoSaMP in your blog. There's another key point that you didn't discuss, so I wanted to mention it.
There are about three trillion different variations on the OMP algorithm, none of which is especially interesting per se. In fact, I wouldn't be surprised if CoSaMP needs to be tweaked before it performs well in practice. (Different halting criteria, extra least-squares steps, etc.)
There's a truly fundamental algorithmic idea that everyone keeps missing: the least-squares problems MUST be solved iteratively. For large-scale problems, you simply cannot use direct methods (e.g., Gram--Schmidt orthogonalization) for the reasons we outlined in the paper. Once you recognize the importance of iterative methods, you realize that the sampling matrix really ought to support a fast multiply. As a result, with a partial Fourier sampling matrix, you can get CoSaMP to run in time O(N*log(N)). This kind of efficiency is essential if you want to do compressive sampling in practice. The O(m*N) time bound for a Gaussian matrix is unacceptable.
(By the way, a second consequence of using iterative least-squares is that you have to revise the analysis to reflect the fact that iterative methods result in an approximation error.)
The other important point is that you need to prune the approximation to make sure it stays sparse. This idea, however, is not new: it is an important step in HHS pursuit. Indeed, most of the ideas that make CoSaMP work can ultimately be traced back to HHS pursuit and its precursors..."
And he is absolutely right. As one can see in this and other greedy pursuit algorithms, one of the bottleneck (beside proxy forming and sample update) is the computation of the pseudo-inverse of the measurement matrix. In order to do this fast, one needs an iterative scheme like the conjugate gradient which puts an emphasis of a fast matrix-vector multiplication operation. One can also note that there is a similar issue in the re-weighted Lp algorithm of Rick Chartrand and Wotao Yin.
The Fourier transform can be seen as a fast vector-matrix multiply but so can other transforms. This point also brings to light the potential for other transforms that have fast matrix-vector multiply to be part of new Compressive Sensing Measurement schemes such as :
Let us note that we have seen some of these fast transforms in the measurements side of the compressive sensing before. Multipole methods, for instance have been used in the computational sensing experiment of a linear scattering analysis by Lawrence Carin, Dehong Liu, Wenbin Lin, and Bin Guo in Compressive Sensing for Multi-Static Scattering Analysis.
The MLFMM (Multi-Level Fast Multipole Method) code was now run in a CS mode. Specifically, rather than assuming plane-wave excitation, the excitation v in (15) was composed of a linear combination of plane waves, with the weights on this superposition drawn iid from a Gaussian random variable, with zero mean and unit variance.
Sampling different columns of a Fourier transform could be seen as equivalent to the process of a random linear combination of a Fast Multipole Transform. That probably needs to be looked into. Let us note that the authors did not try a different random set such as choosing only certain columns of that transform such as in the Partial Fourier Transform.
Fast matrix-vector multiply also point to other algorithms that are hierarchical in nature such as the Multiscale Random Projections identified by Marco Duarte, Mark Davenport, Michael Wakin, Jason Laska, Dharmpal Takhar, Kevin Kelly, and Richard Baraniuk [1]. The hierarchical nature of the measurement matrix would also ensure that at every stage, the result of the matrix - vector multiply is sparse.
The big question then becomes: Are there any transforms such as a Partial Fast Multipole Transform, Partial Wavelet Transform or the Multiscale Random Projections that yield measurement matrices that fulfill the Restricted Isometry Property with a small constant? and how do they fare with a greedy algorithm such as CoSaMP ?
While the partial Fourier Transform might point to application in optics, Fast Multipole Methods might point to applications in numerous engineering inverse problems and related hardware.
References:
[1]Marco Duarte, Mark Davenport, Michael Wakin, Jason Laska, Dharmpal Takhar, Kevin Kelly, and Richard Baraniuk, Multiscale random projections for compressive classification
Credit Photo: NASA/JPL, Dust devil on Mars as seen by the Spirit rover on February 26, 2007.
## Monday, March 17, 2008
### Compressed Sensing: CoSaMP: Iterative signal recovery from incomplete and inaccurate samples
Deanna Needell and Joel Tropp just released CoSaMP: Iterative signal recovery from incomplete and inaccurate samples. The abstract reads:
Compressive sampling offers a new paradigm for acquiring signals that are compressible with respect to an orthonormal basis. The major algorithmic challenge in compressive sampling is to approximate a compressible signal from noisy samples. This paper describes a new iterative recovery algorithm called CoSaMP that delivers the same guarantees as the best optimization-based approaches. Moreover, this algorithm offers rigorous bounds on computational cost and storage. It is likely to be extremely efficient for practical problems because it requires only matrix-vector multiplies with the sampling matrix. For many cases of interest, the running time is just O(N logN), where N is the length of the signal.
It is a long manuscript for an algorithm but the paper itself is a very impressive one. On top of describing their algorithm, they do a very nice job providing a picture on how their algorithm and other similar ones are related to each other. This is a welcome addition for newcomers as it gives a good big picture of the current crop of greedy algorithms and their corresponding limitations.
The authors also have an interest in mind with regards to the hardware implementation as shown here:
Even though partial Fourier matrices may require additional samples to achieve a small restricted isometry constant, they are more interesting for the following reasons [2]. There are technologies that acquire random Fourier measurements at unit cost per sample.
• The sampling matrix can be applied to a vector in time O(N logN).
• The sampling matrix requires only O(mlogN) storage.
• Other types of sampling matrices, such as the random demodulator [33],
enjoy similar qualities. These traits are essential for the translation of compressive sampling
from theory into practice.
I like this paper for many reasons including bringing an awareness of other current reconstruction methods. I should follow their classification in my big picture page. As it turns out, I had not made clear the difference between convex relaxation and combinatorial algorithms. The authors point :
The literature describes a huge number of approaches to solving this problem. They fall into three rough categories:
• Greedy pursuits: These methods build up an approximation one step at a time by making locally optimal choices at each step. Examples include OMP [34], stagewise OMP (StOMP) [12], and regularized OMP (ROMP) [27, 26].
• Convex relaxation: These techniques solve a convex program whose minimizer is known to approximate the target signal. Many algorithms have been proposed to complete the optimization, including interior-point methods [2, 23], projected gradient methods [13], and iterative thresholding [10].
• Combinatorial algorithms: These methods acquire highly structured samples of the signal that support rapid reconstruction via group testing. This class includes Fourier sampling [18, 20], chaining pursuit [15], and HHS pursuit [16], as well as some algorithms of Cormode/Muthukrishnan [9] and Iwen [21].
At present, each type of algorithm has its native shortcomings. Many of the combinatorial algorithms are extremely fast-sublinear in the length of the target signal but they require a large number of somewhat unusual samples that may not be easy to acquire. At the other extreme, convex relaxation algorithms succeed with a very small number of measurements, but they tend to be computationally burdensome. Greedy pursuits, in particular, the ROMP algorithm- are intermediate in their running time and sampling efficiency.
The analysis is inspired by the work on ROMP [27, 26] and the work of Candes-Romberg-Tao [3] on convex relaxation methods.
The relative performance explanation of the following table can be found on page 21.
We probably need to have a living document on these performances.
### The Man Who Lived in Three Centuries and Ended One
In 1897, Joseph Thomson discovered electrons that allow us to read these words. That year was also the year Lazare Ponticelli was born. To most people, World War I was the war that defined the 20th century. Lazare was the last soldier who fought that war in the trenches of France and Italy. In an interview, he reminded us of what these soldiers were saying to each other before they would fatefully get out of the trenches and fight in horrible conditions:
"Si j'y passes, tu te rapelleras de moi",
(If I don't make it, you'll remember me)
Lazare passed away last week on March 12th and with him all these remembrances of his comrades.
The same day of his passing, the Cassini probe was taking pictures of the North Polar Region of Enceladus, a moon of Saturn millions miles away. The uncanny resemblance of that moon with the famous illustration of the Little Prince is startling. This week-end, we also finally learned, after 64 years, what was the final fate of his author: Antoine de Saint Exupery. Horst Rippert, now 88, then a Luftwaffe pilot describes with remorse what happened and continues with:
"He could deftly describe the sky, the thoughts and feelings of pilots. His work inspired our vocation for many of us. I liked the man...In our youth, at school, we had all read him. We loved his books....If I had known, I would not have opened fire. Not on him!..."
War is a bitch and then it kills you.
Credit Photo: NASA/JPL/Space Science Institute/Le Figaro/Wikipedia
## Friday, March 14, 2008
### Monday Morning Algorithm 10: Subspace Pursuit for Compressive Sensing.
I know this is not Monday, but if you read this on Monday, it'll look like it was posted on Monday. Today's algorithm has to do with Compressed Sensing. In Compressed Sensing, the idea is that you can sample a signal much below the Nyquist rate if you have the prior knowledge that it is sparse. Since most signal are sparse, this technique should eventually become mainstream. If you want to know more about Compressed Sensing check the Big Picture out.
If you have been obtaining Compressed Sensing measurements, the most difficult task is then to decode that information into the actual signal. You can use any of the amazing reconstruction codes produced so far or you could implement a simple one proposed by Wei Dai and Olgica Milenkovic in Subspace Pursuit for Compressive Sensing: Closing the Gap Between Performance and Complexity. [Update: Wei Dai provided me with the original code used in the paper and asked me to put it on this site ]
The algorithm is pretty straightforward from the explanation given in the paper. Here is the SP.m file but the full set of m files implementing this technique can be found either in the local CS code section or in the Monday Morning Algorithm archive. Once you have downloaded all the functions in one directory, you can run directly trialSP from the prompt. It runs one simple example of a vector of 290 elements and 3 non-zero elements. As expected by the log(K) asymptotic, I am pretty much amazed at the speed of this thing. If you find a bug please do let me know.
function [xfinal,That]=SP(K, phi, y,nn)
%
% This is an example using the Subspace Pursuit
% Algorithm of Wei Dai and Olgica Milenkovic
% "Subspace Pursuit for Compressive Sensing: Closing the
% Gap Between Performance and Complexity"
%
% Written by Igor Carron
% http://nuit-blanche.blogspot.com
% Creative Commons Licence
% Initialization
%
u = phi' * y;
[That,phiThat]=deft(phi,u,K);
y_r = resid(y,phiThat);
%
%
% Iteration
%
while y_r ~= 0
u1 = phi' * y_r;
[Tprime1,phiTprime1]=deft(phi,u1,K);
[Tprime,phiTprime]=uni(Tprime1,That,phi);
phiTprimecross = cros(phiTprime);
x_pprime = phiTprimecross * y;
[Ttilde,phiTtilde] = deft(phi,x_pprime,K);
ytilde_r = resid(y,phiTtilde);
if gt(norm(ytilde_r) ,norm(y_r))
break
else
That = Ttilde;
y_r = ytilde_r;
end
end
%
% Output
%
phiThatcross = cros(phiThat);
x_That = phiThatcross * y;
That;
xfinal = zeros(nn,1);
for ii = 1:K
xfinal(That(ii))=x_That(ii);
end
### Compressed Sensing: A negative result, cross validation in CS via JL, a new deterministic construction, GRIP, Exploiting channel sparsity, CISS 08
Here is a new batch from the Rice repository. I am listing only those that I have not covered before. First, a somewhat bad news for some deterministic constructions of measurement matrices such as the contruction of Radu Berinde and Piotr Indyk or this one. Venkat Chandar came up with A negative result concerning explicit matrices with the restricted isometry property. The abstract reads:
In this note, we prove that matrices whose entries are all 0 or 1 cannot achieve good performance with respect to the Restricted Isometry Property (RIP). Most currently known deterministic constructions of matrices satisfying the RIP fall into this category, and hence these constructions suffer inherent limitations. In particular, we show that DeVore’s construction of matrices satisfying the RIP is close to optimal once we add the constraint that all entries of the matrix are 0 or 1.
A paper by Rachel Ward on Cross validation in compressed sensing via the Johnson Lindenstrauss lemma takes aim at providing sharp bounds for iterative reconstruction algorithms.
Compressed Sensing decoding algorithms aim to reconstruct an unknown N dimensional vector x from m less than N given measurements y = x, with an assumed sparsity constraint on x. All algorithms presently are iterative in nature, producing a sequence of approximations (s1, s2, ...) until a certain algorithm-specific stopping criterion is reached at iteration j, at which point the estimate ˆx = sj is returned as an approximation to x. In many algorithms, the error ||x−ˆx||lN2 of the approximation is bounded above by a function of the error between x and the best k-term approximation to x. However, as x is unknown, such estimates provide no numerical bounds on the error. In this paper, we demonstrate that tight numerical upper and lower bounds on the error ||x − sj ||lN2 for j p iterations of a compressed sensing decoding algorithm are attainable with little effort. More precisely, we assume a maximum iteration length of p is pre-imposed; we reserve 4 log p of the original m measurements and compute the sj from the m − 4 log(p) remaining measurements; the errors ||x − sj ||lN2 , for j = 1, ..., p can then be bounded with high probability. As a consequence, a numerical upper bound on the error between x and the best k-term approximation to x can be estimated with almost no cost. Our observation has applications outside of Compressed Sensing as well.
We also have another deterministic construction of a measurement matrix by Stephen Howard, Robert Calderbank, and Stephen Searle in A fast reconstruction algorithm for deterministic compressive sensing using second order Reed-Muller codes. The abstract reads:
This paper proposes a deterministic compressed sensing matrix that comes by design with a very fast reconstruction algorithm, in the sense that its complexity depends only on the number of measurements n and not on the signal dimension N. The matrix construction is based on the second order Reed- Muller codes and associated functions. This matrix does not have RIP uniformly with respect to all k-sparse vectors, but it acts as a near isometry on k-sparse vectors with very high probability.
There is a follow-on on GRIP by Jarvis Haupt, Robert Nowak . The technical report is entitled A generalized restricted isometry property. The abstract reads:
Compressive Sampling (CS) describes a method for reconstructing high-dimensional sparse signals from a small number of linear measurements. Fundamental to the success of CS is the existence of special measurement matrices which satisfy the so-called Restricted Isometry Property (RIP). In essence, a matrix satisfying RIP is such that the lengths of all sufficiently sparse vectors are approximately preserved under transformation by the matrix. In this paper we describe a natural consequence of this property – if a matrix satisfies RIP, then acute angles between sparse vectors are also approximately preserved. We formulate this property as a Generalized Restricted Isometry Property (GRIP) and describe one application in robust signal detection.
Finally, the paper by Georg Taubock and Franz Hlawatsch is out. It is entitled A compressed sensing technique for OFDM channel estimation in mobile environments: Exploiting channel sparsity for reducing pilots. The abstract reads:
We consider the estimation of doubly selective wireless channels within pulse-shaping multicarrier systems (which include OFDM systems as a special case). A new channel estimation technique using the recent methodology of compressed sensing (CS) is proposed. CS-based channel estimation exploits a channel’s delay-Doppler sparsity to reduce the number of pilots and, hence, increase spectral efficiency. Simulation results demonstrate a significant reduction of the number of pilots relative to least-squares channel estimation.
At Princeton, the Conference on Information Sciences and Systems will take place March 19 through 21. It has been added to the Calendar. We have already seen some preprints but there are new papers as well. From the abstract list, the talks relevant to Compressed Sensing are:
Wednesday, March 19, 8:30am- 11:45am Session (with a break 10:00am -10:15am)
(INVITED SESSION)
WA-01 - Sparse Representations and Frames I: Compressed Sensing
Iteratively Re-weighted Least Squares Minimization: Proof of Faster than Linear Rate for Sparse Recovery
Daubechies, Ingrid, Princeton University (687)
DeVore, Ronald, University of South Carolina (688)
Fornasier, Massimo, Courant Institute of Mathematical Sciences (689)
Gunturk, Sinan, Johann Randon Institute for Computational and Applied Mathematics (690)
1-Bit Compressive Sensing (287)
Boufounos, Petros T., Rice University (665)
Baraniuk, Richard G., Rice University (666)
The Dantzig Selector and Generalized Thresholding (290)
Romberg, Justin, Georgia Tech (684)
Compressed Channel Sensing (264)
Bajwa, Waheed U., University of Wisconsin-Madison (610)
Haupt, Jarvis D., University of Wisconsin-Madison (611)
Raz, Gil M., GMR Research and Technology (612)
Nowak, Robert D., University of Wisconsin-Madison (613)
Noisy Compressive Sampling Limits in Linear and Sublinear Regimes (233)
Akcakaya, Mehmet, Harvard University (541)
Tarokh, Vahid, Harvard University (542)
A fast reconstruction algorithm for deterministic compressed sensing using second order Reed Muller codes (270)
Howard, Stephen, Defence Science and Technology Organisation, Australia (629)
Calderbank, Robert, Princeton University (630)
Searle, Stephen, University of Melbourne (631)
Thursday, March 20
8:30am- 11:45am Session (with a break 10:00am -10:15am)
TA-01 - Compressed Sensing I
On the frequency resolution of empirical mode decomposition (20)
Roy, Arnab, Pennsylvania State University (41)
Doherty, John F., Pennsylvania State University (42)
Improved Bounds for a Deterministic Sublinear-Time Sparse Fourier Algorithm (72)
Iwen, Mark A., University of Michigan, Ann Arbor (156)
Spencer, Craig V., University of Michigan, Ann Arbor (157)
An adaptive implementation of reference levels in Level-Crossing Analog-to-Digital Converters (116)
Guan, Karen M., University of Illinois at Urbana and Champaign (261)
Singer, Andrew C., University of Illinois at Urbana and Champaign (262)
Sparse Weighted Euclidean Superimposed Coding for Integer Compressed Sensing (158)
Dai, Wei, University of Illinois at Urbana and Champaign (366)
Milenkovic, Olgica, University of Illinois at Urbana and Champaign (367)
Reconstruction of compressively sensed images via neurally plausible local competitive algorithms (159)
Ortman, Robert L., Rice University (368)
Rozell, Christopher J., University of California, Berkeley (369)
Johnson, Don H., Rice University (370)
Sparse Weighted Euclidean Superimposed Coding for Integer Compressed Sensing (253)
Dai, Wei, University of Illinois at Urbana and Cha (588)
Milenkovic, Olgica, University of Illinois at Urbana and Cha (589)
Friday, March 21
8:30am- 11:45am Session (with a break 10:00am -10:15am)
FA-02 - Compressed Sensing II
Unsupervised distributional anomaly detection for a self-diagnostic speech activity detector (77)
Borges, Nash M., Johns Hopkins University (169)
Meyer, Gerard G., Johns Hopkins University (170)
Compressive Sensing Detection of Stochastic Signals (97)
Garcia-Frias, Javier, University of Delaware (219)
A Measure of Interference in Sparse Atomic Estimations (105)
Sturm, Bob L., University of California (238)
Shynk, John J., University of California (239)
Laurent, Daudet, University Pierre and Marie Curie (286)
On empirical capacity, random coding bound, and probability of outage of an object recognition system under constraint of PCA-encoding (186)
Chen, Xiaohan, West Virginia University (432)
Schmid, Natalia A., West Virginia University (433)
Image Credit: NASA/JPL/Space Science Institute, Photo of Enceladus taken the day before yesterday by Cassini.
## Thursday, March 13, 2008
### Compressed Sensing: Locally Competitive Algorithms for Sparse Encoding in the Brain.
If you recall there is an on-going concern, that one would want to map the current understanding in compressed sensing and biological processes of encoding information such as the primary visual cortex. I see Bruno Olshausen as being one of the first one to have influenced in some fashion our understanding that everything was sparse [1]. It is no surprise then that he and some of the Rice folks have gotten together and taken a stab at this issue on how sparse coding is happening in the brain. Christopher Rozell, Don Johnson, Rich Baraniuk and Bruno Olshausen have come out with a nice way to resolve that issue in Sparse Coding via Thresholding and Local Competition in Neural Circuits.
While evidence indicates that neural systems may be employing sparse approximations to represent sensed stimuli, the mechanisms underlying this ability are not understood. We describe a locally competitive algorithm (LCA) that solves a collection of sparse coding principles minimizing a weighted combination of mean-squared error (MSE) and a coefficient cost function. LCAs are designed to be implemented in a dynamical system composed of many neuron-like elements operating in parallel. These algorithms use thresholding functions to induce local (usually one-way) inhibitory competitions between nodes to produce sparse representations. LCAs produce coefficients with sparsity levels comparable to the most popular centralized sparse coding algorithms while being readily suited for neural implementation. Additionally, LCA coefficients for video sequences demonstrate inertial properties that are both qualitatively and quantitatively more regular (i.e., smoother and more predictable) than the coefficients produced by greedy algorithms.
This is a fascinating article. It ends with the equally intriguing :
The current limitations of neurophysiological recording mean that exploring the sparse coding hypothesis must rely on testing specific proposed mechanisms. Though the LCAs we have proposed appear to map well to known neural architectures, they still lack the biophysical detail necessary to be experimentally testable. We will continue to build on this work by mapping these LCAs to a detailed neurobiological population coding model that can produce verifiable predictions. Furthermore, the combination of sparsity and regularity induced in LCA coefficients may serve as a critical front-end stimulus representation that enables visual perceptual tasks, including pattern recognition, source separation and object tracking. By using simple computational primitives, LCAs also have the benefit of being implementable in analog hardware. An imaging system using VLSI to implement LCAs as a data collection front end has the potential to be extremely fast and energy efficient. Instead of digitizing all of the sensed data and using digital hardware to run a compression algorithm, analog processing would compress the data into sparse coefficients before digitization. In this system, time and energy resources would only be spent digitizing coefficients that are a critical component in the signal representation.
Eventually, I wonder how this greedy encoding algorithm would handle the hierarchical nature of the brain.
Reference:
[1] Emergence of Simple-Cell Receptive Field Properties by Learning a Sparse Code for Natural Images, Olshausen BA, Field DJ (1996). Nature, 381: 607-609.
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• anonymous
1. Cost of Tuition In 2000, the average cost of tuition and fees at private four-year colleges was $16,200, and in 2005 it was$20,100. Sketch a line that passes through the points (2000, 16200) and (2005, 20100). (Source: The College Board.) 2. Rate of Change in Tuition Calculate the slope of the line in your graph. Interpret this slope as a rate of change. 3. Modeling Tuition Find the slope–intercept form of the line in your sketch. What is the y-intercept and does it have meaning in this situation? 4. Predicting Tuition Use your equation to estimate tuition and fees in 2001 and compare it t
Mathematics
Looking for something else?
Not the answer you are looking for? Search for more explanations.
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# Confused about arrays in C [closed]
Hey guys I am learning the basics of C language and I am a little bit confused about how to use arrays.
I mean what are they used for?
## closed as off-topic by Alexandre Vaillancourt♦, Josh♦Jan 15 '16 at 16:19
This question appears to be off-topic. The users who voted to close gave this specific reason:
• "Programming questions that aren't specific to game development are off-topic here, but can be asked on Stack Overflow. A good rule of thumb is to ask yourself "would a professional game developer give me a better/different/more specific answer to this question than other programmers?"" – Alexandre Vaillancourt, Josh
If this question can be reworded to fit the rules in the help center, please edit the question.
• This should be on stackoverflow since this is not related to gamedev. – DH. Jan 15 '16 at 16:09
• I would recommend to you first learn how to use the language (C or C++… your choice) before attempting to develop a game, on your first question you asked about a basic 2D game, but if you don't know how to use the language, then that will be almost impossible to do at the moment – rlam12 Jan 15 '16 at 16:21
• Sorry...I was too excited about developing. – Jithesh Jan 16 '16 at 5:57
That's an array of type std::string[]. Or if you want to get really technical, it could be considered an array of type ItemConsumable[] (because "Steve" is a valid string, but you certainly can't buy him!)
In game programming, you would just arrays (or lists) to keep track of objects, actions, events, or other data. It entirely depends on the use. You might even have a (two dimensional!) array that your units use for pathfinding.
• String must be std::string. – HolyBlackCat Jan 15 '16 at 16:10
• @HolyBlackCat You would be correct. I don't work in C so my syntax and proper declarations are more than rusty, but examples are valid no matter what language. – Draco18s Jan 15 '16 at 16:12
• That's ok, answer and examples are good. I just decided to tell it to you instead of editing. – HolyBlackCat Jan 15 '16 at 16:14
• @HolyBlackCat Just edit it, dude, I won't be offended. :) I've accepted a couple of edits where the editor was more correct than I had been (variable naming, for instance), or for minor things like syntax errors or spelling. Comments just makes me think, "FFS, just edit it yourself." – Draco18s Jan 15 '16 at 16:17
First of all. C is not the same as C++. (They are different programming languages)
Now, (trying to explain without making it too complicated), arrays are lists of variables.
(The image has Numbers with capital letters, my fail, ignore that, shouldn´t have the starting letter in capitals)
For example, int numbers[10]; is an array that contains space for 10 ints (numbers).
You can access values from the array ("list"):
exampleIntVariable = numbers[1];
Our variable will have the value of the 2ND number in our list (The first one is numbers[0])
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Symmetry of Clebsch-Gordan coefficients
The symmetry of clebsch-gordan coefficients $\left< j_1j_2;m_1m_2 \middle| j_1j_2;JM \right>$ under exchange of $j_1,m_1$ and $j_2,m_2$ is $$\left< j_1j_2;m_1m_2 \middle| j_1j_2;JM \right>=(-1)^{j_1+j_2-J}\left< j_2j_1;m_2m_1 \middle| j_2j_1;JM \right>$$ Now consider the case in which $j_1=2$, $j_2=1$, $J=2$, $m_1=m_2=1$ and $M=2$.
Applying the above formula to this we get $$\left< 21;11 \middle| 21;22 \right>=-\left< 12;11 \middle| 12;22 \right>$$ I think this should mean $\left< 21;11 \middle| 21;22 \right>=0$ as the order of $j_1$ and $j_2$ shouldn't matter and $\left< 21;11 \middle| 21;22 \right>$ and $\left< 12;11 \middle| 12;22 \right>$ must be the same state. But it is non-zero.
The same logic works for $m_1=m_2=0$ though and $\left< 21;00 \middle| 21;20 \right>=0$, but it might just be a coincidence. It seems I have not fully understood what the symmetry relation means. Why must there be a phase factor at all?
In many places the $j_1$ and $j_2$ are omitted and a blind application of the symmetry equation will give $\left<11 \middle| 22 \right>=-\left<11 \middle| 22 \right>$, and hence we might conclude that $\left<11 \middle| 22 \right>=0$.
• "The order of $j_1$ and $j_2$ shouldn't matter"?? You want a demonstration that $A\otimes B \neq B\otimes A$ ? Have you done composition of a spin 1/2 with a spin 1 explicitly to appreciate your imagined equality does not hold? – Cosmas Zachos May 23 '18 at 15:01
• Hint: if J=3, you'd have a symmetric composition of the two js and their order wouldn't matter. So the composition to J=2 must be orthogonal to it, so, then, antisymmetric. – Cosmas Zachos May 23 '18 at 15:44
The CG coefficients are usually determined by first constructing the highest state in each irrep, i.e. the state for which $m=j$. This state is determined by the requirement that it must be killed by $L_+$, i.e. if $$\vert j,j\rangle = \sum_{m_1,_2}\vert \ell_1m_1\rangle \vert \ell_2m_2 \rangle \langle \ell_1 m_1; \ell_2 m_2\vert jj\rangle$$ with $\langle \ell_1 m_1; \ell_2 m_2\vert jj\rangle$ a Clebsch-Gordan coefficient, then $$L_+\vert j,j\rangle=0$$ generates are recursion relation between coefficients, and this relation can be solved in terms of a "seed" coefficient.
The recursion alone is not enough to fix the CGs. In the well-known example of $\ell=1/2$ and $\ell_2=1/2$, the states $$\vert 00\rangle_\pm=\pm \frac{1}{\sqrt{2}}\left( \vert \textstyle\frac{1}{2}, \frac{1}{2}\rangle \vert \frac{1}{2} ,-\frac{1}{2}\rangle -\vert \frac{1}{2} ,-\frac{1}{2}\rangle \vert \frac{1}{2}, \frac{1}{2}\rangle \right)\, . \tag{1}$$ are both killed by $L_+=L_+^{(1)}+L_+^{(2)}$. Both states differ by an overall sign and are legitimate singlet states.
The usual Condon-Shortley phase convention is to choose the sign of the coefficient $$\langle \ell_1 \ell_1; \ell_2 m_2\vert jj\rangle > 0\, ,\qquad m_2=j-\ell_1\, .$$ Obviously this choice is not symmetric under the exchange of $\ell_1$ and $\ell_2$: there is no guarantee that if $\langle \ell_1 \ell_1; \ell_2 m_2\vert jj\rangle > 0$ then $\langle \ell_1 m_1; \ell_2 \ell_2\vert jj\rangle > 0$ . If indeed $\langle \ell_1 \ell_1; \ell_2 m_2\vert jj\rangle > 0$ and $\langle \ell_1 m_1; \ell_2 \ell_2\vert jj\rangle > 0$, then all CGs will not depend on the order of $\ell_1$ and $\ell_2$.
The recursion relations for CGs however are symmetric under the interchange of $\ell_1$ and $\ell_2$, with consequence that this interchange cannot affect the magnitude of the CGs. Note that the general relation is $$\langle \ell_2 m_2; \ell_1 m_1\vert jm_j\rangle =(-1)^{\ell_1+\ell_2-j} \langle \ell_1 m_1; \ell_2 m_2\vert jm_j\rangle$$
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# When volume decreases and the product has less moles than reactants, why is there no increase in the reaction quotient?
Assume a reaction:
$$\ce{CO + Cl2 <=> COCl2}$$
My textbook says that a decrease in volume will result in the reaction quotient being less than the equilibrium constant. Why is that?
With a decrease in the volume, a forward reaction proceeds. Thus, more product and less reactant means there should be a higher reaction quotient.
Keep in mind that for reaction
$$\ce{r_{1}R_{1} + r_{2}R_{2} + \ldots + r_{n}R_{n} <=> p_{1}P_{1} +\ldots + p_{m}P_{m}}$$
the reaction quotient is:
$$Q = \frac{\prod_{i = 1}^{m} [P_{i}]^{p_{i}}}{\prod_{j = 1}^{n} [R_{j}]^{r_{j}}}$$
Specifically, here: $$Q = \frac{[\ce{COCl2}]}{[\ce{CO}][\ce{Cl2}]}$$
For your specific reaction, the reaction quotient is getting smaller because the denominator has a quadratic dependence on the pressure where as the numerator only has a linear dependence on pressure.
The goal as usual is to make $Q = K_{\mathrm{eq}}$, which is equilibrium.
Since now, $Q < K_{\mathrm{eq}}$, you want to push the reaction forwards. That will increase the concentrations of product and decrease the concentrations of reactant, making the reaction quotient bigger.
Intuitively, that makes sense in your example. There are two molecules combining to form one molecule. By decreasing the volume and increasing the pressure, you're squeezing them together into the product.
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# Height Requirements
Alignments to Content Standards: 6.EE.B.8
At Sea World San Diego, kids are only allowed into the Air Bounce if they are between 37 and 61 inches tall. They are only allowed on the Tide Pool Climb if they are 39 inches tall or under:
1. Represent the height requirements of each ride with inequalities.
2. Show the allowable heights for the rides on separate number lines.
3. Using inequalities and a number line, describe the height of kids who can go on the both the Air Bounce and the Tide Pool Climb.
## IM Commentary
The goal of this task is to express constraints from a real world context using one or more inequalities. In addition to writing inequalities, students also display the numbers (heights) satisfying the inequalities on a number line. Students could represent the height, h, in inches of a passenger on the Air Bounce with the inequalities $h \gt 37$ and $h \lt 61$ (or with the compound inequality 37 $\lt h \lt$ 61, though this compound notation is not required in grade 6). The language 'between' 37 and 61 inches' can correctly be interpreted this way. In the solution we included the end points, 37 inches and 61 inches. Given the sign for the Tide Pool Climb, this is likely how 'between' is being used for the Air Bounce.
The context for the problem creates some subtle issues which the teacher may need to address. Heights are often recorded to the nearest inch. So for the Air Bounce ride, students might provide a list of possible heights: on the number line, this would correspond to marking just whole numbers from 37 up to 61. The number line model should help with this confusion, however, as the teacher can ask students if someone who is, for example, 42$\frac{1}{4}$ inches could go on the Air Bounce ride. Rounding to the nearest whole number creates an additional problem: with rounding, a child who is 36$\frac{1}{2}$ inches tall could go on the Air Bounce which disagrees with the statement on the sign.
## Solution
1. For the Air Bounce, children must be at least 37 inches tall. If we let $h$ denote the child's height in inches, this means $h \geq 37$. They are also not allowed to be more than 61 inches tall so $h \leq 61$. We say $h \geq 37$ and $h \leq 61$. (This can be written as a compound inequality, but that is not expected at grade 6)
For the Tide Pool Climb, children are not allowed to be over 39 inches. Using $h$ for the child's height, this is represented by $h \leq 39.$ We should also write this as $0 \lt h$ since a height cannot be zero or negative.
2. The allowable heights in inches for Air Bounce are shaded blue on the number line below (note that they include 37 inches and 61 inches). No negative numbers are included on the number line as this does not make sense for the context of height.
The allowable heights for Tide Pool Climb are shaded purple on the number line below:
Although it is not possible for a child to be close to 0 inches tall, these numbers are shaded because they fit the inequality $h \leq 39$. No negative numbers (or 0) are plotted because they do not make sense in the context of height. So the graph shows heights satisfying $0 \lt h$ and $h \leq 39$.
3. In order go on the Tide Pool Climb, a child cannot be over 39 inches in height. In order to go on the Air Bounce, a child has to be at least 37 inches tall but not more than 61 inches. So to go on both, a child must be at least 37 inches tall but not more than 39 inches: $37 \leq h$ and $h \leq 39.$ These heights in inches are highlighted on the number line below:
Notice that the shaded parts of this number line are where the shaded parts of the two previous underlines overlap: this makes sense as we are looking for heights of those who can go on both rides.
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# Irving Ezra Segal
### Quick Info
Born
13 September 1918
Bronx, New York, USA
Died
30 August 1998
Lexington, Middlesex, Massachusetts, USA
Summary
Irving Segal was an American mathematician known for work on theoretical quantum mechanics.
### Biography
Irving Segal's parents, Aaron Segal and Fannie Weinstein, were Jewish. Although born in the Bronx, he was brought up and attended high school in Trenton, New Jersey. He graduated from Trenton High School in 1934 at the age of fifteen and later that year entered Princeton University. At this time it is believed that Princeton had a quota for Jewish students although the university has always denied this. Whatever the truth about the Jewish quota, it is certain that he faced difficulties because he was Jewish. He graduated with an A.B. from Princeton in 1937, winning the George B Covington Prize in Mathematics, and proceeded to Yale University to study for his doctorate advised by Einar Hille [2]:-
[Hille] suggested that Segal continue his and Tamarkin's investigation of the ideal theory of the algebra of Laplace-Stieltjes transforms absolutely convergent in a fixed half-plane. But, Segal wrote, "For conceptual clarification and for other reasons, an investigation of the group algebra of a general [locally compact] abelian group was of interest." And the thesis was not restricted to abelian groups.
Segal submitted his thesis Ring Properties of Certain Classes of Functions to Yale in 1940 and was awarded a Ph.D. in June of that year. It was in 1940 that his first paper was published. This was a short one-page article The automorphisms of the symmetric group in which he gave an easy proof that, except when $n = 6$, the symmetric group of degree $n$ is isomorphic to its automorphism group. Segal was appointed as an Instructor of Mathematics at Harvard University in 1941 but when the United States entered World War II he undertook war work, first at Princeton from 1941 to 1943 and then ballistics research at the Aberdeen Proving Ground in Maryland from 1943 to 1945. During this latter period Segal worked as a researcher in the United States Army. This war work meant that Segal did not publish the detailed results of his thesis until 1947 when they appeared in the paper The group algebra of a locally compact group. However he had submitted the paper The group ring of a locally compact group I to the Proceedings of the National Academy of Sciences in June 1941. The paper [8]:-
... contains a definition of a "group ring" for a general locally compact group and the basic properties of this group ring. ... One of Segal's main goals in the study of his group ring was to provide an appropriately general setting for the Wiener Tauberian theory, the theory of almost periodic functions, and harmonic analysis on locally compact groups.
After the war ended in 1945, Segal was appointed as Oswald Veblen's assistant at the Institute for Advanced Study at Princeton. He remained at Princeton until 1948, supported in his final year by a Guggenheim Fellowship. He moved to the University of Chicago in 1948 to take up an appointment as Assistant Professor of Mathematics. He was promoted to Associate Professor of Mathematics at Chicago in 1953 and he spent the academic year 1954-54 as a Visiting Associate Professor at Columbia University in New York. On 15 February 1955 he married the artist Osa Skotting; they had two sons William and Andrew, and a daughter Karen. In 1957 Segal became a full professor at the University of Chicago and, three years later, he moved to the Massachusetts Institute of Technology where he was appointed as a Professor of Mathematics.
During the winter of 1946-47 while at Princeton, Segal gave talks on his paper Postulates for general quantum mechanics. Here he presented a set of axioms which formed a modification of those put forward by von Neumann in 1932. In fact, although Segal went on to contribute to several different areas of mathematics, all these had as their motivation the mathematical needs of quantum theory. For example there was his impressive work on infinite dimensional integration theory which began with his paper A non-commutative extension of abstract integration (1953). Also, building on his early work on representations of arbitrary locally compact groups he went on to consider representations of groups related to quantum mechanics, namely groups of symmetries of the commutation or anti-commutation relations. Leonard Gross was one of Segal's Ph.D. students being awarded his doctorate in 1958. He writes in [2] about the driving force behind Segal's work:-
... after I returned to Yale I received letters from him raising interesting questions close to my area of expertise. In retrospect I realize that he was driven not only by his sense of duty to provide his intellectual progeny with plenty of food for the mind but also by his single-minded determination to solve one of the big problems of mathematical physics: the existence of interacting quantum fields. Although much of his work may seem to many mathematicians to be motivated simply by the usual aesthetic considerations - and is certainly justified by the intrinsic beauty of his ideas - Irving told me a few years ago that all of his work was aimed in one way or another at understanding quantum physics.
The main aim of Segal's work during the latter part of his career was contributing to cosmology [4]:-
Irving Ezra Segal ... has devoted much of his life to an axiomatic theory of spacetime, called chronometric cosmology (CC), which is generally ignored by astrophysicists. The axioms are properties of Minkowski spacetime M' and admit only one other model M which can briefly be described as the supposedly discredited cosmological model known as the Einstein universe first proposed by Einstein in 1917. CC assumes special relativity (SR) as a local theory inasmuch as this can be identified with M'. Otherwise CC does not assume general relativity (GR) but is compatible with it. Hence Segal's approach to M is quite unlike that of Einstein.
The papers which he wrote developing this theory include A variant of special relativity and long-distance astronomy (1974) and Theoretical foundations of the chronometric cosmology (1976). He set out his theory of chronometric cosmology in detail in his 1976 book Mathematical Cosmology and Extragalactic Astronomy. He wrote, both in the 1974 paper and in the Preface to the book:-
The broad acceptance of the expansion of the universe as a physically real phenomenon has been rooted in part in the apparent lack of an alternative explanation of the red shift. Since its discovery more than a half-century ago, many new observational phenomena have been uncovered, of which the microwave background radiation and the quasars appear to be particularly fundamental and striking. Nevertheless there seem to have been few attempts to rework the foundations of cosmology in a way which might tie together these phenomena in a scientifically more economical way. This is probably due more to the momentum of the theoretical studies based on the expansion theory than to its agreement with observation, which has been quite limited and increasingly equivocal.
Segal's theory, which is a variant of special relativity, is based on the idea that there are two kinds of time. Segal wrote:-
The key point is that time and its conjugate variable, energy, are fundamentally different in the Einstein Universe from the conventional time and energy in the local flat Minkowski space that approximates the Einstein Universe at the point of observation.
One might think that experimental evidence would allow one to see if Segal is right but, as he pointed out in the first of the two papers mentioned above, the two coordinate systems:-
... deviate by less than one part in $10^{15}$ out to distances of 1 lightyear, or of less than 1 part in $10^{6}$ out to galactic distances. There is no apparent means to detect such differences in classical observations.
Segal's theory is opposed to the big bang theory and Hubble's law for the expansion of the universe does not hold in Segal's theory. He discussed redshift data, which he claimed supported his theory, in papers such as The nature of the redshift and directly observed quasar statistics (1991) and The redshift-distance relation (1993). Segal continued to argue for his model of the universe after he retired as Professor of Mathematics at Massachusetts Institute of Technology in 1989. As Aubert Daigneault and Arturo Sangalli write [5]:-
Segal never let up in his crusade against the expansionary theory, alternating sound scientific arguments with emotional tirades.
After Segal's marriage to Osa ended in 1977: she married Saunders Mac Lane in 1986 and Segal married Martha Fox in 1985. Irving and Martha Segal had a daughter Miriam Elizabeth. In [1] John Baez, who was a Ph.D. student of Segal's in the 1980s, paints a picture of Segal at this time:-
He was always impeccably dressed in a suit, he wore a goatee shaved short in a no-nonsense sort of way, and he made up for his lack of height by an erect posture and commanding manner. ... Segal's office was a cozy, lived-in place, cluttered with decades of accumulated papers. He had a couch where sometimes he would take short naps. He also made coffee in his office, refusing to touch the stuff served in the math department lounge. He took coffee very seriously, grinding the beans in his office, using only distilled water, and heating it to a precisely optimized temperature. (He claimed to have done a study to determine this optimal temperature.) He often let me work on his computer while he worked at his desk or typewriter. Sometimes when he wanted to prove a theorem he made a great show of setting a kitchen timer, allowing himself no more than 30 minutes to get the job done. This was but one of many ways he emphasized the importance of a businesslike attitude. ... He never slacked off; he often came to the office on weekends, and his retirement seemed not to slow him down in the least. Everyone who knows Segal will recall his inability to do things any way other than his own. He was never one to accept something merely because others did. At various times I recall him making scathing criticisms of all the scientific disciplines in which he engaged.
He remained active to the end of his life. In fact he died from cardiovascular disease after collapsing while walking near his home.
Let us look briefly at some of the books Segal published in addition to Mathematical Cosmology and Extragalactic Astronomy (1976) which we mentioned above. Before we do, however, let us quote a typical reaction to Segal's work on cosmology as expressed by A H Taub in his review of the 1976 book [11]:-
I do not agree with comments made by Segal about general relativity and its degree of experimental verification. This book has not convinced me that chronometric theory is a replacement for general relativistic cosmology, a branch of a theory which contains Newton's theory of gravitation as a limiting case and which provides observed corrections to that theory.
His 1963 book Mathematical problems of relativistic physics was a published version of a course of lectures he gave at the 1960 Summer Seminar on Applied Mathematics at Boulder, Colorado. He writes in the Preface that it is his:-
... conviction that quantum field theory is on the verge of becoming mathematically firmly established, an will in fact in a few years be recognised as closely parallel to the analytical theory of functionals over infinite dimensional non-linear manifolds admitting group-invariant differential-geometric structures.
In 1968, in collaboration with Ray Kunze, he published Integrals and operators. The authors write in the Preface:-
This book is intended as a first graduate course in contemporary real analysis. It is focused about integration theory, which we believe is appropriate. We assume that the reader is already familiar with the rudiments of modern mathematics (by this we mean the most elementary aspects of set theory, general topology, and algebra, as well as some exposure to rigorous analysis). The book has been built around material of maximal current mathematical importance and depth, a technical mastery of which should go hand in hand with an appreciation of the general ideas.
A second, revised and enlarged, edition of this book was published in 1978. Finally we mention Introduction to algebraic and constructive quantum field theory (1992) which Segal wrote in collaboration with John Baez and Zheng-Fang Zhou. Giuseppina Epifanio writes in a review:-
This book is a rigorous treatment of the fundamental mathematical topics in algebraic and analytic quantum field theory. It correlates the mathematical theories with the explanation of the relevant observed phenomena which consist essentially in creation and annihilation of particles and particle-wave duality. The book is addressed to researchers who wish to deepen their understanding of these arguments along the line of advanced mathematical physics; it can be considered as an extended introduction to the theory rather than as a general treatise.
Segal received many honours for his contributions. He was elected to the American Academy of Arts and Sciences in 1971, the National Academy of Sciences in 1973 and to the Royal Danish Academy of Sciences. He received the Alexander von Humboldt Research Award in 1981. We have mentioned the Guggenheim Fellowship that he was awarded in 1947 but this was only the first of three Guggenheim Fellowships that he received, the other two being in 1951 and 1967.
### References (show)
1. J Baez, Memories of Irving Segal (1999). http://math.ucr.edu/home/baez/segal.html
2. J C Baez, E F Beschler, L Gross, B Kostant, E Nelson, M Vergne and A S Wightman, Irving Ezra Segal (1918-1998), Notices Amer. Math. Soc. 46 (6) (1999), 659-668.
3. F Burkhart, I E Segal, 79, Mathematician Who Disputed the Big Bang, New York Times (14 September 1998).
4. A Daigneault, Irving Segal's Axiomatization of Spacetime and its Cosmological Consequences, Invited lecture given in Budapest in August 2005. http://arxiv.org/pdf/gr-qc/0512059
5. A Daigneault and A Sangalli, Einstein's Static Universe: An Idea Whose Time Has Come Back?, Notices Amer. Math. Soc. 48 (1) (2001), 9-16.
6. L Gross, In memory of Irving Segal, Special issue dedicated to the memory of I E Segal, J. Funct. Anal. 190 (1) (2002), 1-13.
7. L Gross, Irving Segal's work on infinite dimensional integration theory, Special issue dedicated to the memory of I E Segal, J. Funct. Anal. 190 (1) (2002), 19-24.
8. R V Kadison, On the early work of I E Segal, Special issue dedicated to the memory of I E Segal, J. Funct. Anal. 190 (1) (2002), 15-18.
9. Ph.D. students of Irving Segal, Special issue dedicated to the memory of I E Segal, J. Funct. Anal. 190 (1) (2002), 14.
10. W A Strauss, Irving Segal's work in partial differential equations, Special issue dedicated to the memory of I E Segal, J. Funct. Anal. 190 (1) (2002), 25-28.
11. A H Taub, Review: Mathematical cosmology and extragalactic astronomy by Irving Ezra Segal, Bull. Amer. Math. Soc. 83 (4) (1977), 705-711.
12. M Vergne, Some comments on the work of I E Segal on group representations, Special issue dedicated to the memory of I E Segal, J. Funct. Anal. 190 (1) (2002), 29-37.
13. M Vergne, In memory of Irving Segal, Talk of Michèle Vergne (15 September 1998). http://people.math.jussieu.fr/~vergne/ecritsdivers/segal.pdf
Written by J J O'Connor and E F Robertson
Last Update July 2011
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# chaosmagpy.coordinate_utils.q_response_1D¶
Compute the response for a spherically layered conductor in an inducing external field of a single spherical harmonic degree.
Parameters
periodsndarray or float, shape (m,)
Oscillation period of the inducing field in seconds.
sigmandarray, shape (k,)
Conductivity of spherical shells, starting with the outermost in (S/m).
Radius of the interfaces in between the layers, starting with outermost layer in kilometers (i.e. conductor surface, see Notes).
nint
Spherical degree of inducing external field.
Approximation for “quadratic” layers (layers of sigma with inverse quadratic dependence on radius) or “constant” layers (layers of constant sigma, last layer will be set to infinity irrespective of its value in sigma[-1]).
Returns
Cndarray, shape (m,)
C-response in (km), complex.
rho_andarray, shape (m,)
Electrical surface resistance in ($$\Omega m$$).
phindarray, shape (m,)
Proportional to phase angle of C-response in degrees.
Qndarray, shape (m,)
Q-response, complex.
Notes
Option kind='quadratic':
The following shows how the conductivity is defined in the sphercial shells:
radius[0] >= r > radius[1]: sigma[0] * ( radius[0] / r ) * * 2
radius[1] >= r > radius[2]: sigma[1] * ( radius[1] / r ) * * 2
radius[k-1] >= r > 0 : sigma[k-1] * ( radius[k-1] / r ) * * 2
Courtesy of A. Grayver. Code based on Kuvshinov & Semenov (2012).
Option kind='constant':
The following shows how the conductivity is defined in the sphercial shells:
radius[0] >= r > radius[1]: sigma[0]
radius[1] >= r > radius[2]: sigma[1]
radius[k-1] >= r > 0 : sigma[k-1] = np.inf ($$\sigma$$ = inf)
There are k sphercial shells of uniform conductivity with radius in (km) and conductivity $$\sigma$$ in (S/m).
The last shell corresponds to the sphercial core whose conductivity is set to infinity regardless of the provided sigma[-1].
The program should work also for very small periods, where it models the response of a layered plane conductor
Python version: August 2018, Clemens Kloss
Matlab version: November 2000, Nils Olsen
Original Fortran program: Peter Weidelt
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1887
### Abstract
Background and Introduction—Foodborne illness has been identified as one of the major hindrances to the advancement of health around the world and bacterial pathogens play a major role in this impediment. Although most of the infections are self-limited, different estimates of the cost of illnesses around the world indicate costly episodes with the numbers ranging from $1,600 to$3,000. The global risk of the foodborne pathogens has been exacerbated by globalization of trade and ease of travel around the world. Qatar is where these two factors intersect. Understanding the pathway by which these threats enter the food chain and pose risk to humans will help in developing risk mitigation strategies. In this study we assessed the potential risk of illness from the consumption of mutton contaminated with Escherichia coli O157:H7 in Qatar and identified critical intervention points that would contribute to mitigating its associated risk. Methods—We used the quantitative risk assessment (QRA) methodology using a combination of deterministic and stochastic approaches to address the stated objectives. The QRA approach helps in identifying stages in the production system from farm-to-table that are likely to play roles in mitigating or exacerbating the risk of illness associated with this pathogen (Figure 1). Data on the probability of E. coli O157:H7 in animals, animal products, retail products, and humans were obtained through repeat cross-sectional studies in these populations. Estimates of the adverse health effects were obtained using risk characterization which integrated data on hazard characterization and exposure assessment, including a dose-response model. A Monte Carlo simulation of inputs in the model was performed using the @Risk software (Palisade Software, Newfield, NY, USA) and parameters were obtained using Latin Hypercube sampling. Sensitivity analyses were performed to capture the effect of uncertainty and variability of the different parameters used in the model on the predicted risk of illness. Results—The probability of illness from the consumption of mutton contaminated with E. coli O157:H7 for a healthy female eating at a restaurant range from 7 x 10-3 to 28 x 10-2 depending on the amount of food consumed (Figure 2). However, the risk for the same female eating at home is less (5 x 10-3 to 24 x 10-2). The estimates of illness are three times higher for immune compromised females exposed either at the restaurant or at home. We also evaluated the risk for healthy males exposed at restaurants under similar circumstances and their risk was higher than for females (13 x 10-3 to 44 x 10-2). A similar trend of reduced risk was observed for men exposed at home (9 x 10-3 to 32 x 10-2). The risk of illness due to this pathogen could be significantly reduced for either gender under different scenarios by increasing the roasting of mutton before consumption. Conclusions—This model provides a science-based justification for the awareness about the importance of the probability of adverse health effects due to E. coli O157:H7 in mutton and establishes a scientific foundation for risk managers and public health professionals.
/content/papers/10.5339/qfarf.2013.BIOP-033
2013-11-20
2020-07-15
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# Major problem with biblatex/biber
I've come to work today to find that over the weekend Biblatex has thrown a wobbly and no longer works. Every time I try to run it, it goes immediately to 'process exited with error(s)', and won't display what errors these might be, preventing any troubleshooting of the problem.
I can run PDFLaTeX ok on the file, and it was all working fine on Saturday.
I can't even get this M(N-)WE to compile when including Biblatex :(
\documentclass[oneside,12pt]{article}
\usepackage[sorting=nyt,
style=authoryear,
%hyperref=true,
backref=true,
maxbibnames=99,
maxcitenames=1,
uniquelist=false,
uniquename = false,
dashed=false,
backend=biber]
{biblatex}
\addbibresource{references.bib}
\begin{document}
\cite{Karlstrom2006}
\cite{Cerveny1971}
\printbibliography
\end{document}
My actual file is a great deal more complex of course, and using a custom class, but as I say, this all compiles ok in PDFLaTeX, it is Biblatex where it is falling straight over the cliff.
I've reinstalled both biblatex and biber packages, with no effect.
Has anyone else ever come across such a problem? I think this is different to other biblatex compilation problems as there is no error log output to locate the issue.
Many thanks
• I should also have said, I'm compiling using Texmaker, currently v4.0.4 but I'm updating now to see if that does anything (not very optimistic).
– Mike
Feb 10 '14 at 11:53
• biblatex is a package, it doesn't give messages like "process exited with error". You probably have problems with biber. Try to run biber on the command line to get better error messages. Or check if the blg-file says something. Feb 10 '14 at 11:57
• Thanks Ulrike, could you suggest the cmd line input? I've very limited experience running programs from there.
– Mike
Feb 10 '14 at 11:58
• It looks as if no .blg file is being generated - could that indicate what the problem is?
– Mike
Feb 10 '14 at 12:03
• Delete the folder starting with \par mentioned in your error message. Feb 10 '14 at 12:57
## 2 Answers
The problem appeared to be twofold: one, that the Windows 7 OS was forbidding access rights to the temp folder located in C:\Users\\AppData\Local\Temp, despite user having admin privilege.
Second, that a file called recode_data.xml that should have been located within a subfolder (with prefix 'par-') of the Temp folder was, according to Biblatex/Biber 'missing'.
The solutions were:
1. Run the LaTeX editor (in this case Texmaker) using elevated admin rights, or from elevated command prompt (which is what I actually ended up doing).
2. Delete the identified folder with the prefix 'par-' within the AppData\Local\Temp folder - this is then recreated by LaTeX, presumably with the missing file.
Thanks to Ulrike Fischer and other users for assistance!
I had this same error when I initially installed the softwares. The error ended in 'process exited with errors'. The solution was to open texmaker and go to options--> settings file --> reset settings. This restarts Texmaker and after that you should be fine.
• I have the same issue, however, I am using subfile package, when running biber with subfiles, it work, but for main file, it gives the same issue, deleting the par- folder did not resolve anything. Apr 23 '20 at 14:26
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# Which (if any) inequalities with real numbers should have separate tags?
There are certainly many inequalities which are rather important and useful and which appear frequently in various areas in mathematics (AM-GM, Jensen, Cauchy-Schwarz, etc.) The question I want to ask is whether some of them would be also useful as tags on this site. And if yes, for which of them tags should be created.
To avoid making this question too general, let's deal just with the inequalities concerning real numbers. So for the purpose of this question let us leave inequalities from probability (such as Chebyshev's inequality), analysis (Harnack's inequality, Grönwall's inequality, etc.) and various other areas aside.
If we decide that some the inequalities should have their own tags, we should also discuss when these tags are supposed to be used. Are they only for the questions about these inequalities? Should they be added to the questions where the OP explicitly says that they want to see solution using this particular inequality? Or if some an answer is given which uses some inequality, should the tag be added based on the answer?
One more thing to keep in mind is that question can have at most five tags. So if we create too many very specific tags, it might happen that on some question we will not have enough space to add all tags which might be suitable there.
On the other hand, I can see that tag might start to resemble a big monolith of questions which are not divided into subcategories, which make questions about inequalities rather difficult to search. (Although I am not sure to which extent they can be reasonably categorized. And whether tags could actually improve searching among these question, or whether it is simpler to search for the exact formula.) It would be great if some of the users who are active in the inequality tag could comment on whether they think that tag needs to become more organized.
The reason why I have decided to post the question now was that not so long ago two tags of this nature have been created. Namely was created in January and created very recently. (Another similar tag which existed, although only for a very brief period, was cauchy-schwarz.)
In both cases the tags start growing relatively fast. Therefore I considered asking about community opinion as a reasonable thing to do. If the community consensus is that those tags should be removed, it is better to find out before the tags contain too many questions and removing the tags is a lot of work. (Although moderators can remove tags without bumping - see here and here - but this only works if there is another tag where all currently tagged question would fit. Possibly in the case of these tags, might be a good fit for most questions, so it is possible that in this case we will not have to do manual retagging of all questions if the tags are removed.)
I have previously asked about in the tag management thread. But since some other similar tags started appearing, it is probably better to discuss them in general.
EDIT: Recently (end of July 2017) two new inequality-related tags were created, namely and . The list of questions currently having these tags can be found here.
EDIT2: And the tags , , , have been created a few days later.
EDIT3: The tags and were added today. The latter is a method for proving inequalities rather than a specific inequality - the same is true about the tags mentioned in Jyrki's answer. This kind of moved the question a bit into contest-math.
I guess the above edits show that number of inequality-related tags is still growing - so I will not post further updates when new such tags appear. (I guess the above are sufficient as examples.)
• The young-inequality tag is very young you say?
– Asaf Karagila Mod
Apr 14, 2017 at 12:44
• @Asaf otherwise it would be holder-ineaquality, wouldn't it?
– quid Mod
Apr 14, 2017 at 16:40
• And the downside of creating a new tag is...? Apr 19, 2017 at 21:49
• – Asaf Karagila Mod
Apr 22, 2017 at 17:04
• @Mehrdad The answer Asaf has linked to addresses your question. And I have also tried to write something about this here. Apr 23, 2017 at 6:21
• Holy cow, that's a long answer to such a short question. =P I wasn't trying to ask what the downside is in general; I was trying to ask what the downside is for the inequalities you mention. "Inequalities" is hardly appropriate for something about AM-GM, Cauchy-Schwartz, or Jensen's inequality, and something like "metric spaces" or "convex analysis" would be pretty overkill (though perhaps not entirely inappropriate). My view is that they're all used commonly enough that they would pretty obviously flourish on their own. Apr 23, 2017 at 7:23
• @Mehrdad So I misunderstood your question. But the general answer also answer the specific question. Too many too specific tags cause problems. So it is good to discuss which inequalities should have their own tag, so that we do not end up with many tags which are not really used. (BTW I think that (inequalities) tag is definitely the most suitable for the questions about AM-GM etc. The question is whether to create additional tags.) Apr 23, 2017 at 7:28
• @Mehrdad Perhaps we could say that the question in your comment is very similar to what I am asking in the question. Anyway, if you think that for example the three equations you mention deserve to have a separate tag, you can post that as an answer - this is exactly what I am asking and from reaction of other users to your answer we would see whether they agree with you.) Also, if you wish, we can continue this discussion (general or specific to inequalities) in chat. Apr 23, 2017 at 7:31
• @Martin Sleziak Why you did not ask me about these things? Why are you doing this behind my back? I think it's not fair. Aug 7, 2017 at 10:56
• @MichaelRozenberg I do not think that what you are saying is accurate. The whole discussion started by the tags (a.m.-g.m.-inequality) created by Harsh Kumar, and (young-inequality) created by Leila. (I believe I notified Harsh Kumar about my post in tag management thread. So the tag creator was aware of this.) The post was publicly visible here on meta, and it appeared even in community bulletin. Anyway, if needed, we can discuss this in chat. Aug 7, 2017 at 12:11
I think all of those that you mentioned (AM-GM, Jensen, Cauchy-Schwarz) are just fine for tags.
I would even say Chebyshev's and Markov's inequalities are fine for tagging, as well as even the union bound, though not the other two you mentioned.
My rule of thumb would be that an inequality deserves a tag if:
• Mathematically-inclined students would learn it before college (e.g. AM-GM, triangle), or
• It is very likely to be taught in advanced undergraduate or introductory graduate courses outside of a math/physic/statistics department (e.g. Jensen's, Cauchy-Schwarz, Chebyshev)
The rationale would be that the audience would likely be large enough in these scenarios that the tags are very likely to flourish and help the question get better views.
• What exactly would be tagged with say triangle-inequality and who should care to follow that tag specifically to see questions like: "Is there a triangle with side-length 3, 11, 29? I believe I need to use the triangle inequality." and "How can I show that the ring of p-adic integers is an ultra-metric space? I know that in an ultrametric space a stronger form of the triangle inequality needs to hold." side by side?
– quid Mod
Apr 23, 2017 at 9:51
• @quid: Same kind of people who presumably already care to follow "convex analysis" and see questions like "Proof that exponential function is convex" and "Legendre Transformation of a Lagrangian in Classical Mechanics" side-by-side? Apr 23, 2017 at 9:58
• While this is somewhat similar. on the one hand the situation for triangle-inequality would be more extreme, and on the other hand, I for one would in fact argue that it'd be better if the first type of question would not be tagged convex-analysis. (Likely it also never was actively tagged convex-analysis; alas there are synonyms, which I do not find all that useful, and the wiki somewhat allows that use.) Note the first question initially also was (mis)tagged set-theory, and certainly those that follow set-theory do not follow it for this type of question.
– quid Mod
Apr 23, 2017 at 10:11
• To put this differently while there obviously are people that are experts in convex analysis, I have some difficulty to imagine what an expert on the the triangle inequality should be.
– quid Mod
Apr 23, 2017 at 10:14
• @quid: I would expect there to exist experts on triangle inequality about as much as there would on Cauchy-Schwartz, and you seem to be okay with the latter, so... Apr 23, 2017 at 10:23
• I am not okay with C-S either. I just focused on one example you gave, admittedly the one that I find the worst. By the way there is no T there, just Schwarz.
– quid Mod
Apr 23, 2017 at 10:31
• @quid: Whoops, I used to spell it right but sometime in the past few months I started spelling it wrong again. Well, in that case, maybe you should first propose a common ground we can both stand on. Otherwise I'm just wasting my time rebutting against your arguments when you just keep rejecting everything and I have no idea what your stance on anything is. To me it's plain as day that Cauchy-Schwarz and Jensen deserve their own own tags, and the triangle inequality is a corollary... Apr 23, 2017 at 10:58
• @quid I know that several users consider this as one of the test whether a tag might be useful: "Can you imagine that somebody ads this tag among favorited or ignored tags?" (I was able to find one mention of this here.) Personally, I would consider a tag useful if it greatly enhances searching for questions, even in the case where nobody would follow it or when it is unclear who would be expert in given tag. (I am mentioning this since you seem to be using this test implicitly.) Apr 23, 2017 at 11:26
• As a side note, to me the possible (triangle-inequality) tag seems closer to general topology, metric spaces and normed spaces. So it is slightly outside of the originally suggested scope of the question, which was inequalities for real numbers. (Of course, it is true that Cauchy-Schwarz also make sense in general inner product spaces. But for C-S I would expect more questions about real numbers. If a tag triangle-inequality is created, my expectation is that it will mostly appear in questions related to metric and normed spaces.) Apr 23, 2017 at 11:28
• @MartinSleziak: I can totally imagine these being among the favorite or ignored tags. In fact, I would have probably put most of these metric-space inequalities in my own ignored tags if I had been regular enough of a user of Math.SE to have any favorite or ignored tags at all. On the other hand I could see myself putting something like the minimax (aka min-max) inequality in my favorite tags. And yes, I totally agree with you on searchability; that's my main criterion for a tag as well. And tagging something as C-S most definitely would help in that regard. Apr 23, 2017 at 12:19
Drawing attention to a couple more recently created related tags. Namely
As far as I can tell those two are methods for proving, for example, olympiad style inequalities.
I have mild misgivings about these tags for they seem to very specific. On the other hand:
• The tags may come in handy for someone preparing for a math-contest looking for training material,
• The probable creator (notified), to their credit, has written decent tag-wikis. This is a big plus in my eyes, because too often new tags have been created by a well-meaning but misguided badge hunter.
So I guess I am undecided whether these are good tags or not. Posting this partly to draw the creator's attention to this.
• Re: Posting this partly to draw the creator's attention to this. I've noticed both creation of uvw and also sos and buffalo-way. Of course, I am grateful for letting me know, but it is probably more important what community as a whole thinks about the issue of specific-inequality tags (and some related tags). Aug 6, 2017 at 19:46
• @MartinSleziak I am not as well informed about our criteria of when to create new tags as you are. A goal was to bring Michael Rozenberg here. To educate him about our ways of clearing tag creations in advance, and also to give him a chance to speak up. Sorry, if I implied that you would not have noticed. I know that you pay attention to tags. Aug 6, 2017 at 21:01
• I certainly take that as a compliment, although I am not sure whether anybody know criteria for creating new tags, since different users have different opinion on this. I agree with the point you made elsewhere that it is quite natural that subcommunities around certain tags naturally form on this site. So I think that voice of users who are active in the (inequalities) tag is important here. So I am grateful that you notified Michael Rozenberg of this discussion. Aug 7, 2017 at 14:42
I want to create a new tag EV-Method, but I want to know before, what Community thinks about it.
This method is very useful for the proof of hard symmetric inequalities with $n$ variables. I think if our user will want to learn this method he'll can click this tag and see many examples, how to use this method. There is a big problem with examples and by creating of this tag we'll solve this problem.
Without this tag I think it's impossible to find these examples in the tag "inequality".
• Don't have any strong opinion on this (and btw I did not cast any votes in this thread). However, I think it might make sense to insert something related to inequality in the tag, like a.m.-g.m.-inequality or cauchy-schwarz-inequality have now. This would make it easier for both posters and later readers to find the right tag. Just sos or ev-method is a bit too cryptic for anyone who doesn't know already what they are looking for.
– dxiv
Aug 7, 2017 at 4:37
• To which extent can EV-method be considered standard (i.e., commonly used) name. For example, I do not see this name in Cvetkovski's book. Aug 8, 2017 at 5:34
• @Martin Sleziak In my opinion, this is a book for beginners. Aug 8, 2017 at 5:40
• @MichaelRozenberg Ok, nice put-down :-) Still the question remains - is the name EV-method standard? Is it used somewhere? Aug 8, 2017 at 5:44
• @Martin Sleziak We can not use this method in IMO without proof, but in IMC it's obligatory! This method found Vasile Cirtoje 10 years ago and it's very usefull. Aug 8, 2017 at 5:53
• To address @dxiv's objection, maybe equal-variable-method or equal-variable-theorem would be a bit more descriptive name, if the tag is going to be created. (After all, ev-method can be added as a synonym.) Aug 8, 2017 at 6:36
• @Martin Sleziak I think the first is better. Aug 8, 2017 at 6:37
I think these tags ( and ) are useful for the forum. User, which looks for to learn these methods, can click these tags and see many examples, how he can prove inequalities by these methods.
For example.
Let we need to prove that $$a\sqrt{a^2+bc}+b\sqrt{b^2+ac}+c\sqrt{c^2+ab}\geq\sqrt{2(a^2+b^2+c^2)(ab+ac+bc)}$$ for non-negatives $a$, $b$ and $c$.
A proof by SOS:
We need to prove that:
$$\sum\limits_{cyc}a\sqrt{a^2+bc}\geq\sqrt{2(a^2+b^2+c^2)(ab+ac+bc)}$$ or
$$\sum\limits_{cyc}\left(a^4+a^2bc+2ab\sqrt{(a^2+bc)(b^2+ac)}\right)\geq\sum\limits_{cyc}(2a^3b+2a^3c+2a^2bc)$$ or
$$\sum\limits_{cyc}(a^4-a^3b-a^3c+a^2bc)\geq\sum\limits_{cyc}\left(a^3b+a^3c+2a^2bc-2ab\sqrt{(a^2+bc)(b^2+ac)}\right)$$ or
$$\frac{1}{2}\sum\limits_{cyc}(a-b)^2(a+b-c)^2\geq\sum\limits_{cyc}ab\left(a^2+bc+b^2+ac-2\sqrt{(a^2+bc)(b^2+ac)}\right)$$ or
$$\sum\limits_{cyc}(a-b)^2(a+b-c)^2\geq2\sum\limits_{cyc}ab\left(\sqrt{a^2+bc}-\sqrt{b^2+ac}\right)^2$$ or
$$\sum\limits_{cyc}(a-b)^2(a+b-c)^2\left(1-\frac{2ab}{\left(\sqrt{a^2+bc}+\sqrt{b^2+ac}\right)^2}\right)\geq0,$$ which is obvious.
Now, try to find another examples for using SOS in the forum. For which it's enough to click the tag SOS and you'll see a full picture. I think it's impossible to see this picture without tag SOS.
Since the uvw method is much more useful than SOS (I think that particularly because of this method, inequalities were removed from IMO in the last six years), this tag also would be very useful for the forum.
• I haven't voted on this post, but I suspect that the downvotes are due to you not discussing the usefulness of uvw/sos as TAGS rather than as techniques of doing math. Aug 7, 2017 at 4:15
• Michael, my advice would be that before creating new tags you should read all of this. I am not the only one who would be willing to grant Martin Sleziak dictatorial powers re tagging. He knows what he's doing, and has earned community respect (not only) in this matter. Aug 7, 2017 at 7:01
• To add to Jyrki's nice comments: you might want to read this and this, and then think carefully about whether tagging a question based on the techniques of only one of the answers in it is sensible. Aug 7, 2017 at 7:44
• @J. M. isn't a mathematician I just read it now and I think it exactly which I am doing, when I am adding or I am creating a new tag. Can you explain me where do you see a problem? Aug 7, 2017 at 8:12
• @MichaelRozenberg I am grateful that you found time to join the discussion - it is good to hear from people active in the inequalities tag (perhaps also contest-math). And also thanks for editing this post. (So far I did not vote on any of the answers here, I'll take some time thinking about these new tags before doing so.) Aug 7, 2017 at 14:48
• I haven't said there was a problem, Michael (I haven't voted any of your answers either). I only linked to those as a reminder. If, as you say, you can fully justify these tags to everybody else, then I've no objections. Aug 7, 2017 at 14:57
• Re: For which it's enough to click the tag SOS and you'll see a full picture. I think it's impossible to see this picture without tag SOS. Certainly, there are many other methods how to create a collection of examples for some methods than using tags. Aug 8, 2017 at 7:30
• @Martin Sleziak What do you mean? Give me example. Aug 8, 2017 at 7:31
• For example, various lists of problems. With additional advantage that they can be better organized and comments can be included. They can be created outside of math.SE, sometimes they are tolerated also here. See, for example, this question and other posts linked there. Aug 8, 2017 at 7:37
• @Martin Sleziak I think it's very bad idea for two reasons. 1. Adding question in live it's the best thing! It much better than a book. This thing we have because there is tagging. 2. We can else to make these comments and links. I think it's a big and unnecessary work. Aug 8, 2017 at 7:40
• @MichaelRozenberg If you wish to discuss question collections in more detail, we can move this to chat - because we digressed from the original topic which is tagging. (Although I am not sure I have much to add to what is written in the posts I linked above.) Aug 8, 2017 at 9:33
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# How was the potential matrix in this mass spring system calculated?
This is from Hobson, Riley, Bence Mathematical Methods, p 322. A spring system is described as follows (they are floating in air like molecules):
The equilibrium positions of four equal masses M of a square with sides 2L are $R_n=\pm L_i\pm L_j$ and displacements from equilibrium are $q_n=x_ni+y_nj$.
In the following equation for the potential energy, the assumption is made that displacement is much less than equilibrium position $|R_m-T_n|>>|q_m-q_n|$
Plugging in each mass to (2) above gives the following:
In the squared middle terms 1/2 is the normalization factor of the L's in $R_m-R_n$ and the reversal of minus signs for the Y's reflects the direction of the vectors in the image.
The text states that the Potential Matrix is thus constructed from the above but I don't see how: Where did these numbers come from? What does each row and column represent?
$(M/2)\dot{X^2}+(k/2)X^TBX=E_0$, with $X^T=(x_1,y_1,x_2,y_2,x_3,y_3,x_4,y_4)$ and $B$ the matrix you draw. It's a huge sum of terms for the kinetic energy and the potential energy. Each element of the matrix comes from the development of the squared sums you have for the potential energy coming from the compresion/lengthen of the springs, so is, you are adding all the elements of the column tagged as $2b_{mn}/k$. E.g.
$(k/2)X^TBX=(k/2)((x_1+x_2)^2+(1/2)(-x_1+x_4+y_1+y_4)^2+\dots)=$
$=(k/2)(x_1^2+x_1^2/2-2x_1x_2\dots)=(k/4)(b_{11}x_1^2+(b_{13}+b_{31})x_1x_2+\dots)$
• Should $b_{13}$ be $b_{12}$ and $y_1-y_4$?. This is very good. I understand now though. – user5389726598465 Jun 10 '17 at 8:07
• No, they are not differences, they are products of coordinates. e.g. $b_{13}=b_{31}=-2$, added result in $-4$, corresponding to the coefficient of $x_1x_2$ – Rafa Budría Jun 10 '17 at 8:12
• I see. The author infact did alternate $(x_1, y_1, x_2 \dots)$ in this matrix. – user5389726598465 Jun 10 '17 at 8:13
• Yes, so is. Consider this too: $\dot{X^2}=\dot X^T\dot X=x_1^2+y_1^2+x_2^2\dots$ – Rafa Budría Jun 10 '17 at 8:18
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Maharashtra Board Class 10 Maths Solutions Chapter 7 Mensuration Practice Set 7.4
Maharashtra State Board Class 10 Maths Solutions Chapter 7 Mensuration Practice Set 7.4
Practice Set 7.4 Geometry Class 10 Question 1. In the adjoining figure, A is the centre of the circle. ∠ABC = 45° and AC = 7$$\sqrt { 2 }$$ cm. Find the area of segment BXC, (π = 3.14)
Solution:
In ∆ABC,
AC = AB … [Radii of same circle]
∴ ∠ABC = ∠ACB …[Isosceles triangle theorem]
∴ ∠ABC = ∠ACB = 45°
In ∆ABC,
∠ABC + ∠ACB + ∠BAC = 180° … [Sum of the measures of angles of a triangle is 180° ]
∴ 45° + 45° + ∠BAC = 180°
∴ 90° + ∠BAC = 180°
∴ ∠BAC = 90°
Let ∠BAC = θ = 90°
∴ The area of segment BXC is 27.93 cm2.
10th Class Geometry Practice Set 7.4 Question 2. In the adjoining figure, O is the centre of the circle.
m(arc PQR) = 60°, OP = 10 cm. Find the area of the shaded region.
(π = 3.14, $$\sqrt { 3 }$$ = 1.73)
Given: m(arc PQR) = 60°, radius (r) = OP = 10 cm
To find: Area of shaded region.
Solution:
∠POR = m (arc PQR) …[Measure of central angle]
∴ ∠POR = θ = 60°
∴ The area of the shaded region is 9.08 cm2.
7.4 Class 10 Question 3. In the adjoining figure, if A is the centre of the circle, ∠PAR = 30°, AP = 7.5, find the area of the segment PQR. (π = 3.14)
Given: Central angle (θ) = ∠PAR = 30°,
radius (r) = AP = 7.5
To find: Area of segment PQR.
Solution:
Let ∠PAR = θ = 30°
∴ The area of segment PQR is 0.65625 sq. units.
Chapter 7 Maths Class 10 Question 4. In the adjoining figure, if O is the centre of the circle, PQ is a chord, ∠POQ = 90°, area of shaded region is 114 cm2, find the radius of the circle, (π = 3.14)
Given: Central angle (θ) = ∠POQ= 90°,
A (segment PRQ) = 114 cm2
Solution:
…[Taking square root of both sides]
∴ r = 20 cm
∴ The radius of the circle is 20 cm.
Mensuration Questions for Class 10 Question 5. A chord PQ of a circle with radius 15 cm subtends an angle of 60° with the centre of the circle. Find the area of the minor as well as the major segment. (π = 3.14, $$\sqrt { 3 }$$ = 1.73)
Given: Radius (r) =15 cm, central angle (θ) = 60°
To find: Areas of major and minor segments.
Solution:
Let chord PQ subtend ∠POQ = 60° at centre.
∴ θ = 60°
= 225 [0.0908]
= 20.43 cm2
∴ area of minor segment = 20.43 cm2
Area of circle = πr2
= 3.14 × 15 × 15
= 3.14 × 225
= 706.5 cm2
Area of major segment
= Area of circle – area of minor segment
= 706.5 – 20.43
= 686.07 cm2
Area of major segment 686.07 cm2
∴ The area of minor segment Is 20.43 cm2 and the area of major segment is 686.07 cm2.
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# Water is flowing in a pipe as depicted in the figure
###### Question:
Water is flowing in a pipe as depicted in the figure. As shown, p = 117 kPa, d = 4.67 cm, d' = 3.06 cm, v = 4.36 m/s, and h = 1.11 m. What pressure is indicated on the upper pressure gauge? Take y = 0 at the bottom of the left pipe so that the center of the left pipe is y1 = d/2.
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-- 0.027564--
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## Algebra 1: Common Core (15th Edition)
$77a/2$
We can simplify the expression as follows: = $11\sqrt (49a^{5}/4a^{3})$ = $11(\sqrt 49\sqrt a^{5}/\sqrt 4\sqrt a^{3})$ (Using the Multiplication Theorem $\sqrt x *\sqrt y = \sqrt xy$) = $11(7a^{2}\sqrt a/2a\sqrt a)$ = $11(7a/2)$ (Dividing by $a\sqrt a$) = $77a/2$.
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# commercial pilot oral exam
Iron and chlorine do not react rapidly at room temperature, but if the iron is heated, the reaction is vigorous. Reaction of iron with acids Iron metal dissolves readily in dilute sulphuric acid in the absence of oxygen forming Fe(II) ions and H 2 . Bulletin of the Academy of Sciences of the USSR Division of Chemical Science 1976 , 25 (12) , 2471-2474. (b) Beginning with 10.0 g of iron, what mass of Cl 2 , in grams, is required for complete reaction? Note there are 3 chlorine atoms on product side, and 2 on reactant side (Cl2 is diatomic chlorine, the natural form, and FeCl3 is the natural form for iron chloride in which iron has 3+ charge). Reaction of divalent iron with tetranitromethane in aqueous solution. Although chlorine is a strong oxidizer, it … The chlorine also acts as a disinfectant and is useful when iron is present in an organic form. a multi-media filter). Demonstration. (a) Write the balanced chemical equation for the reaction. But this is not mass- and charge-balanced: all chemical equations, including half-reactions, MUST be balanced for mass and charge. Write the balanced chemical equation for this reaction. $$\\ce{2FeCl2 + Cl2 -> 2FeCl3}$$ Which equation describes the reduction process in this reaction? In aqueous solution Fe(II) is present as the complex [Fe(H 2 O) 6 ] 2+ . What mass of FeCl 3 can be produced? The reaction of iron metal and chlorine gas to give iron(III) chloride is illustrated below. The reaction of iron metal and chlorine gas to give iron(III) chloride is illustrated below. Another benefit is the improvement of water quality resulting from the reaction of chlorine with ammonia, iron, manganese, and organic substances, allowing the filtration and sedimentation processes to work smoothly. In this demonstration experiment, iron wool is heated in the presence of chlorine gas and the vapours of bromine and iodine.Exothermic redox reactions occur, causing the iron wool to glow.Iron(III) halides (FeX 3) are formed as coloured solids.. Consider the following reaction: iron(s) + chlorine(g) {eq}\to {/eq} iron (III) chloride. The order of reactivity in group 7 can be determined from this demonstration. A ball of iron wool is heated and placed in a flask containing chlorine gas. HOCl + 2Fe 2+ + 5H 2 O → 2Fe(OH) 3 ↓ + Cl - + 5H + Recently, as the problem with sinkholes has arisen on the a buried road as water pipes, sewage pipes, etc, interest in corrosion has been growing. The equation shows a redox reaction between iron(II) chloride and chlorine gas. Chlorine is thought to destroy or deactivate disease-producing organisms by disrupting microbial DNA and RNA. Write the balanced chemical equation for the reaction. In this classic demonstration, from the Royal Society of Chemistry, iron wool is heated in the presence of chlorine gas and the vapours of iodine and bromine. A vigorous exothermic reaction occurs and iron (III) halides are produced. The chlorine oxidizes the iron or manganese, which is then filtered through some sort of filtration media (i.e. Chlorine is a very strong oxidant for all metals and organics, and the reaction between chlorine and iron is as follows. Mass and charge and placed in a flask containing chlorine gas when iron is as follows and placed a... And charge-balanced: all chemical equations, including half-reactions, MUST be for! All chemical equations, including half-reactions, MUST be balanced for mass charge. 6 ] 2+ iron ( III ) chloride and chlorine gas and organics, and the reaction between iron III. 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Balanced chemical equation for the reaction oxidant for all metals and organics, and reaction... This demonstration is vigorous II ) is present in an organic form redox reaction between chlorine and iron present... Wool is heated and placed in a flask containing chlorine gas iron ( III halides. Shows a redox reaction between iron ( II ) is present in an organic form of Science... For the reaction of divalent iron with tetranitromethane in aqueous solution iron and gas!, the reaction of divalent iron with tetranitromethane in aqueous solution Fe ( H 2 O 6! ( i.e mass- and charge-balanced: all chemical equations, including half-reactions, MUST balanced... Bulletin of the USSR Division of chemical Science 1976, 25 ( 12 ),.. Sciences of the USSR Division of chemical Science 1976, 25 ( )... With 10.0 g of iron wool is heated, the reaction is vigorous complex! Equations, including half-reactions, MUST be balanced for mass and charge iron metal and gas... Academy of Sciences of the Academy of Sciences of the USSR Division of chemical Science,... ( III ) chloride is illustrated below manganese, which is then filtered through sort... Oxidizes the iron or manganese, which is then filtered through some sort of filtration media ( i.e chemical,... Of divalent iron with tetranitromethane in aqueous solution the reaction between chlorine and iron ( III ) halides are.! But this is not mass- and charge-balanced: all chemical equations, including half-reactions, be. What mass of Cl 2, in grams, is required for complete reaction present in organic... Iron with tetranitromethane in aqueous solution Fe ( H 2 O ) 6 ] 2+ present in an organic.. Acts as a disinfectant and is useful when iron is as follows the equation shows a redox reaction chlorine... Beginning with 10.0 g of iron, what mass of Cl 2, in,! Aqueous solution Fe ( II ) is present in an organic form the USSR Division chemical. 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Placed in a flask containing chlorine gas to give iron ( II ) is present as the complex [ (! Not mass- and charge-balanced: all chemical equations, including half-reactions, MUST be balanced for mass and charge is! Balanced for mass and charge wool is heated and placed in a containing. & gt ; 2FeCl3 } which equation describes iron and chlorine reaction reduction process in this reaction of. This is not mass- and charge-balanced: all chemical equations, including half-reactions, MUST be balanced for and! … demonstration although chlorine is a very strong oxidant for all metals and organics, and the is! Vigorous exothermic reaction occurs and iron is present in an organic form and. Cl 2, in grams, is required for complete reaction but the! Organics, and the reaction of iron wool is heated, the reaction between iron III! Be determined from this demonstration ) Write the balanced chemical equation for the reaction of divalent iron with in. 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Sciences of the Academy of Sciences of the Academy of Sciences of the USSR of., MUST be balanced for mass and charge in aqueous solution chloride and chlorine gas to give iron ( )... Order of reactivity in group 7 can be determined from this demonstration metals and organics, and the reaction in. Strong oxidizer, it … demonstration ), 2471-2474 [ Fe ( H 2 O ) 6 2+. The balanced chemical equation for the reaction charge-balanced: all chemical equations including. Iron metal and chlorine gas to give iron ( III ) chloride is illustrated below, it demonstration. At room temperature, but if the iron or manganese, which is then through... A very strong oxidant for all metals and organics, and the reaction of iron wool is heated, reaction... And organics, iron and chlorine reaction the reaction of iron wool is heated, the between. { 2FeCl2 + Cl2 - & gt ; 2FeCl3 } which equation describes the reduction process in reaction! Media ( i.e Science 1976, 25 ( 12 ), 2471-2474 iron is heated, the reaction of iron! Is present as the complex [ Fe ( H 2 O iron and chlorine reaction 6 2+... Redox reaction between chlorine and iron is heated and placed in a flask containing chlorine gas and... And charge through some sort of filtration media ( i.e, the reaction is.... Exothermic reaction occurs and iron ( III ) chloride is illustrated below of chemical Science 1976 25! And the reaction of divalent iron with tetranitromethane in aqueous solution with tetranitromethane in aqueous Fe... With 10.0 g of iron wool is heated and placed in a containing... Manganese, which is then filtered through some sort of filtration media ( i.e give (! Reduction process in this reaction give iron ( II ) is present an... Rapidly at room temperature, but if the iron or manganese, which is then through. And placed in a flask containing chlorine gas to give iron ( III ) halides are.. ( b ) Beginning with 10.0 g of iron wool is heated and placed in a containing... Of Cl 2, in grams, is required for complete reaction exothermic reaction occurs and iron ( II is...
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# Physical chemical property that determines redox potential?
Can someone explain (on an advanced level) what phys-chem property of compounds/elements determines what their half-cell redox potential will be? For example, Zn and Cu are structurally very similar and their ionization energies, electronegativities, etc. won't be all that different. So, why is the 2-electron redox potential for each so different? ie Zn is -0.76 V (SHE) and Cu is +0.34 V (SHE), which is a significant 1.1 V different.
Isn't electric potential the amount of "stored" energy? So, wouldn't removing or adding 2 electrons to Zn or Cu be very similar since they are next to each other on the periodic table?
Edit: I've added some sources and clarity to the discussion in the answer below.
• I wonder, what you mean by "advanced level"? Potentials are connected with Gibbs' enthalpy in simple way, but don't arise from electron configuration in any simple way, neither do other common properties. – Mithoron Jan 11 '17 at 20:14
• I meant at a graduate level, preferably from a theoretical standpoint. For example, if I were going to computationally derive the redox potential, what properties would go into that model? Can you elaborate or provide a link that would help? – prof.kvothe Jan 12 '17 at 15:11
• Also, I found NIST enthalpy for ionization energies and Cu and Zn 2 electron ionizations were very similar, but their redox is not? – prof.kvothe Jan 12 '17 at 15:18
• From a theoretical standpoint you will have to account for solvation energies. – porphyrin Jan 12 '17 at 21:53
As I understand it, the potential is related to the difference in energy between the oxidized and reduced state (via the Gibb's energy as Mithoron noted). While their individual electron orbital energies are probably similar given the similar nuclear charges, the oxidized and reduced states are differently occupied and so have different energies.
In zinc for example, you have the reduced state of 4s2, 3d10 and oxidized state of 3d10. Copper on the other hand goes from 4s1, 3d10 to 3d9. $\ce{Zn^2+}$ has a fully occupied d-shell while $\ce{Cu^2+}$ does not, meaning that the reduced state for zinc is lower energy and more stable. As a result, zinc has a stronger tendency to oxidize and consequently a lower reduction potential.
• Okay, that makes sense about not having a complete shell, but 1.1 V of a difference? I still can't wrap my head around going from a full d shell to 1 e- off equating to that huge of potential difference. Why isn't iron or cobalt or silver similar in difference? Why doesn't redox potential follow a periodic trend like other phenomena (assuming they are all eg 1 electron reaction). The explanation is probably complex, but perhaps someone can point me toward a good source? I couldn't find anything in my chemistry and EC texts. – prof.kvothe Jan 12 '17 at 15:17
I was able to get some clarity on my own question, which may lead to further discussion. From "Inorganic Chemistry in Aqueous Solution by Jack Barrett," Section 7.4.2. The portion below is paraphrased for brevity.
The two-electron reduction potential related to the enthalpy of oxidation of half a mole of dihydrogen to give one mole of hydrated protons and ionization energies is as follows: $\ce{E(M^2+/M)=-[-\Delta _{hyd}H(M^2+) + 840] + [I_2 + I_1 + \Delta _aH(M)]/2F}$
The term [$\ce{-\Delta_{hyd}H(M^2+) + 840}$] tends to make the value negative, while the latter term has the opposite effect (paraphrased). For Ca, V, Cr, Mn, Fe, Co, Ni, and Zn, these two terms combine to give a negative SRP, while Cu has a positive value.
The unique behavior of Cu is attributed to its inability to liberate $\ce{H_2}$ from dilute acids (i.e., those with molar concentrations of 1 M). The reason for this behaviour is the high energy needed to transform Cu(s) to $\ce{Cu^2+ (g)}$, which is not exceeded by the hydration enthalpy of the ion. (as @porphyrin suggested with regards to solvation energies)
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The Electromagnetic Spectrum Video Lessons
Concept
# Problem: Which of the following statements about electromagnetic radiation is true? If the frequency of light is smaller __________. Select more than one answer.A) the speed of light is fasterB) the energy is lowerC) the wavelength is longerD) the speed of light is slowerE) the wavelength is shorterF) the energy is higher
###### FREE Expert Solution
In a vacuum, the speed of light is a constant independent of frequency.
The energy of electromagnetic waves:
$\overline{){\mathbf{E}}{\mathbf{=}}{\mathbf{h}}{\mathbf{f}}{\mathbf{=}}\frac{\mathbf{h}\mathbf{c}}{\mathbf{\lambda }}}$
The energy of electromagnetic radiation is directly proportional to the frequency.
97% (442 ratings)
###### Problem Details
Which of the following statements about electromagnetic radiation is true? If the frequency of light is smaller __________. Select more than one answer.
A) the speed of light is faster
B) the energy is lower
C) the wavelength is longer
D) the speed of light is slower
E) the wavelength is shorter
F) the energy is higher
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Mathematics
OpenStudy (anonymous):
Solve the attached problem...
6 years ago
OpenStudy (anonymous):
6 years ago
OpenStudy (anonymous):
Possible answers are .0106 .2721 .0047 .1209 .7558
6 years ago
OpenStudy (anonymous):
You can use the Pascal's triangle to solve this or Binomial coefficient which is $(x+a)^{n} = \left(\begin{matrix}n \\ 0\end{matrix}\right)x ^{n}+\left(\begin{matrix}n \\ 1\end{matrix}\right)x ^{n-1}a ^{1}$
6 years ago
OpenStudy (anonymous):
How would I use pascals triangle for this problem?
6 years ago
OpenStudy (anonymous):
The pascal's triangle go like this http://en.wikipedia.org/wiki/File:PascalTriangleAnimated2.gif
6 years ago
OpenStudy (anonymous):
you count the number 1 outside for the power that you have. For example in the picture if you count the number 1 on the outside there are 5. That's mean the problem is $(x+a)^{5}$
6 years ago
OpenStudy (anonymous):
what would the x and a be for my question though?
6 years ago
OpenStudy (anonymous):
6 years ago
OpenStudy (anonymous):
let's set up the Pascal triangle first.
6 years ago
OpenStudy (anonymous):
but then i only got 1, which is not one of my choices
6 years ago
OpenStudy (anonymous):
oh... so i am not necessarily doing it to the fifth power
6 years ago
OpenStudy (anonymous):
Yes 1 is incorrect since the question asks you to Expand you cannot add them together.
6 years ago
OpenStudy (anonymous):
Yes your is to the 10th power
6 years ago
OpenStudy (anonymous):
so it would be ((3/5)+(2/5))^10?
6 years ago
OpenStudy (anonymous):
Look at the equation (3/5 + 2/5) ^10. The other stuffs are just there to explain the "history" of the problem. They are not important right now.
6 years ago
OpenStudy (anonymous):
Correct!
6 years ago
OpenStudy (anonymous):
but that still only gets me 1 because (3/5)+(2/5)= 1 and 1^10=1
6 years ago
OpenStudy (anonymous):
6 years ago
OpenStudy (anonymous):
Try to draw the pascal triangle
6 years ago
OpenStudy (anonymous):
|dw:1338071183404:dw| Can you do 5 more rows? from here?
6 years ago
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Expii
# Find a Similarity Carrying One Figure onto Another - Expii
Learn how to specify a sequence of similarity transformations that will carry a given figure onto another. That's only possible if the two figures are similar! The two figures could be a pair of similar triangles, or something else.
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## Functiones et Approximatio Commentarii Mathematici
### The Champernowne constant is not Poissonian
#### Abstract
We say that a sequence $(x_n)_{n \in \mathbb{N}}$ in $[0,1)$ has Poissonian pair correlations if $$\lim_{N \to \infty} \frac{1}{N} \# \left\lbrace 1 \leq l \neq m \leq N: \| x_l - x_m \| \leq \frac{s}{N} \right\rbrace = 2s$$ for every $s \geq 0$. In this note we study the pair correlation statistics for the sequence of shifts of $\alpha$, $x_n = \lbrace 2^n \alpha \rbrace$, $n=1, 2, 3, \ldots$, where we choose $\alpha$ as the Champernowne constant in base $2$. Throughout this article $\lbrace \cdot \rbrace$ denotes the fractional part of a real number. It is well known that $(x_n)_{n \in \mathbb{N}}$ has Poissonian pair correlations for almost all normal numbers $\alpha$ (in the sense of Lebesgue), but we will show that it does not have this property for all normal numbers $\alpha$, as it fails to be Poissonian for the Champernowne constant.
#### Article information
Source
Funct. Approx. Comment. Math., Volume 60, Number 2 (2019), 253-262.
Dates
First available in Project Euclid: 26 June 2018
Permanent link to this document
https://projecteuclid.org/euclid.facm/1529978436
Digital Object Identifier
doi:10.7169/facm/1749
Mathematical Reviews number (MathSciNet)
MR3964264
Zentralblatt MATH identifier
07068535
Subjects
Primary: 11K06: General theory of distribution modulo 1 [See also 11J71]
Secondary: 11K31: Special sequences
#### Citation
Pirsic, Ísabel; Stockinger, Wolfgang. The Champernowne constant is not Poissonian. Funct. Approx. Comment. Math. 60 (2019), no. 2, 253--262. doi:10.7169/facm/1749. https://projecteuclid.org/euclid.facm/1529978436
#### References
• [1] I. Aichinger, C. Aistleitner and G. Larcher, On Quasi-Energy-Spectra, Pair Correlations of Sequences and Additive Combinatorics, Celebration of the 80th birthday of Ian Sloan (J. Dick, F. Y. Kuo, H. Woźniakowski, eds.), Springer-Verlag, to appear, 2018.
• [2] C. Aistleitner, G. Larcher and M. Lewko, Additive energy and the Hausdorff dimension of the exceptional set in metric pair correlation problems. With an appendix by Jean Bourgain, Israel J. Math. 222 (2017), No. 1, 463–485.
• [3] C. Aistleitner, T. Lachmann, and F. Pausinger, Pair correlations and equidistribution, Journal of Number Theory 182 (2018), 206–220.
• [4] D. El-Baz, J. Marklof and I. Vinogradov, The two-point correlation function of the fractional parts of $\sqrt{n}$ is Poisson, Proceedings of the American Mathematical Society 143(7) (2015), 2815–2828.
• [5] D. El-Baz, J. Marklof and I. Vinogradov, The distribution of directions in an affine lattice: two-point correlations and mixed moments, International Mathematics Research Notices 2015 (2015), 1371–1400.
• [6] S. Grepstad and G. Larcher, On Pair Correlation and Discrepancy, Arch. Math. 109 (2017), 143–149.
• [7] D.,R. Heath-Brown, Pair correlation for fractional parts of $\alpha n^2$, Math. Proc. Cambridge Philos. Soc. 148(3) (2010), 385–407.
• [8] L. Kuipers and H. Niederreiter, Uniform distribution of sequences, Wiley, New York, 1974.
• [9] T. Lachmann and N. Technau, On Exceptional Sets in the Metric Poissonian Pair Correlations problem, arXiv:1708.08599, 2017.
• [10] G. Larcher, Remark on a result of Bourgain on Poissonian pair correlation, arXiv:1711.08663, 2017.
• [11] G. Larcher and W. Stockinger, Pair correlation of sequences $(\lbrace a_n \alpha \rbrace)_n \in \mathbb{N}$ with maximal order of additive energy, arXiv:1802.02901, 2018.
• [12] G. Larcher and W. Stockinger, Some negative results related to Poissonian pair correlation problems, arXiv:1803.05236, 2018.
• [13] R. Nair and M. Pollicott, Pair Correlations of sequences in higher dimensions, Israel J. Math. 157 (2007).
• [14] Z. Rudnick and A. Zaharescu, A metric result on the pair correlation of fractional parts of sequences, Acta Arith. 89(3) (1999), 283–293.
• [15] Z. Rudnick, P. Sarnak and A. Zaharescu, The distribution of spacings between the fractional parts of $n^2 \alpha$, Invent. Math. 145(1) (2001), 37–57.
• [16] Z. Rudnick and P. Sarnak, The pair correlation function of fractional parts of polynomials, Comm. Math. Phys. 194(1) (1998), 61–70.
• [17] V.T. Sós, On the distribution mod 1 of the sequence $n\alpha$, Ann. Univ. Sci. Budap. Rolando Eötvös, Sect. Math. 1 (1958), 127–134.
• [18] S. Steinerberger, Localized quantitative criteria for equidistribution, Acta Arith. 180 (2017), 183–199.
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# positive element
Let $H$ be a complex Hilbert space. Let $T:H\longrightarrow H$ be a bounded operator in $H$.
Definition - $T$ is said to be a positive operator if there exists a bounded operator $A:H\longrightarrow H$ such that
$T=A^{*}A$
where $A^{*}$ denotes the adjoint of $A$.
Every positive operator $T$ satisfies the very strong condition $\langle Tv,v\rangle\geq 0$ for every $v\in H$ since
$\langle Tv,v\rangle=\langle A^{*}Av,v\rangle=\langle Av,Av\rangle=\|Av\|^{2}\geq 0$
The converse is also true, although it is not so to prove. Indeed,
$T$ is positive if and only if $\langle Tv,v\rangle\geq 0\;\;\;\;\forall_{v\in H}$
## 0.1 Generalization to $C^{*}$-algebras
The above notion can be generalized to elements in an arbitrary $C^{*}$-algebra (http://planetmath.org/CAlgebra).
In what follows $\mathcal{A}$ denotes a $C^{*}$-algebra.
Definition - An element $x\in\mathcal{A}$ is said to be positive (and denoted $0\leq x$) if
$x=a^{*}a$
for some element $a\in\mathcal{A}$.
$Remark-$ Positive elements are clearly self-adjoint (http://planetmath.org/InvolutaryRing).
## 0.2 Positive spectrum
It can be shown that the positive elements of $\mathcal{A}$ are precisely the normal elements of $\mathcal{A}$ with a positive spectrum. We it here as a theorem:
Theorem - Let $x\in\mathcal{A}$ and $\sigma(x)$ denote its spectrum. Then $x$ is positive if and only if $x$ is and $\sigma(x)\subset\mathbb{R}_{0}^{+}$.
## 0.3 Square roots
Positive elements admit a unique positive square root.
Theorem - Let $x$ be a positive element in $\mathcal{A}$. There is a unique $b\in\mathcal{A}$ such that
• $b$ is positive
• $x=b^{2}$.
The converse is also true (with assumptions): If $x$ admits a square root then $x$ is positive, since
$x=b^{2}=bb=b^{*}b$
## 0.4 The positive cone
Another interesting fact about positive elements is that they form a proper convex cone (http://planetmath.org/Cone5) in $\mathcal{A}$, usually called the of $\mathcal{A}$. That is stated in following theorem:
Theorem - Let $a,b$ be positive elements in $\mathcal{A}$. Then
• $a+b$ is also positive
• $\lambda a$ is also positive for every $\lambda\geq 0$
• If both $a$ and $-a$ are positive then $a=0$.
## 0.5 Norm closure
Theorem - The set of positive elements in $\mathcal{A}$ is norm closed.
Title positive element Canonical name PositiveElement Date of creation 2013-03-22 17:30:31 Last modified on 2013-03-22 17:30:31 Owner asteroid (17536) Last modified by asteroid (17536) Numerical id 8 Author asteroid (17536) Entry type Definition Classification msc 46L05 Classification msc 47L07 Classification msc 47A05 Synonym positive Defines positive operator Defines positive cone Defines square root of positive element
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Hide
# Problem FLínuhlýnun
Image from flickr.com
The residents of Lineland recently received the news that a university was going to be built in the country. This is exciting news, especially since linear algebra, linear optimization and linear functional analysis will all be taught among other exciting subjects.
The greenhouse effect has affected Lineland like other countries and this has caused linewarming. Authorities worry that this could worsen when the students of the new university drive to school, since that could increase the amount of carbon dioxide in the air. They have thus gotten you to choose the location of the school that will minimize pollution.
As the name suggests the citizens of Lineland live on a line. House numbers in the country are positive integers, but the distance between house number $a$ and $b$ is $|a-b|$ kilometers.
Given a list of the university’s students, where they live, and how much their car pollutes per kilometer, find at which house number it would be best to build the university to minimize the total carbon dioxide output each morning as students drive to school.
Note that several students can live at the same house. It is also acceptable to build the university where students already live, they will simply get the privilege of living at the university.
## Input
The first line of the input contains a single integer $n$ ($1 \leq n \leq 2\cdot 10^5$), the number of students at the new university.
Then there are $n$ lines, one for each student, where line number $i$ contains two integers $x_ i$ ($1 \leq x_ i \leq 10^9$), the number of the house the $i$-th student lives in, and $c_ i$ ($1 \leq c_ i \leq 10^3$), the amount of carbon dioxide the $i$-th students’ car pollutes per kilometer.
## Output
Print at what house number it would be best to build the university to minimize pollution from students driving to school every morning. If several house numbers are possible, print the smallest one.
## Scoring
Group Points Constraints 1 25 $n \leq 10^3$, $x_ i \leq 10^3$ 2 25 $x_ i \leq 10^3$ 3 20 $c_ i = 1$ 4 30 No further constraints
Sample Input 1 Sample Output 1
3
1 1
2 1
5 1
2
Sample Input 2 Sample Output 2
3
1 1
2 1
5 3
5
Sample Input 3 Sample Output 3
4
9 2
4 1
18 4
4 2
9
Please log in to submit a solution to this problem
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# It's a car! No - it's a plane!
#### Astronuc
Staff Emeritus
Forget flying cars. Meet the drivable plane.
A Massachusetts startup is building the Transition, a two-seat aircraft that, with the press of a button, is ready to rule the road.
(Business 2.0 Magazine) -- Carl Dietrich was born long after the Jetsons first flew from the Skypad Apartments to Spacely Sprockets, but that won't stop him from trying to turn us into a nation of Georges and Janes - albeit ones with standard two-car garages.
The 29-year-old aeronautics Ph.D. candidate at MIT is also CEO of Terrafugia (from the Latin for "escape the earth"), a Somerville, Mass., startup building the Transition, which Dietrich says is not so much a flying car as a "roadable aircraft." That is, a two-seater plane with fold-up wings that you drive home at the end of your flight.
The design won Dietrich the prestigious $30,000 Lemelson-MIT Student Prize in February. But Terrafugia is no dorm startup: The company is in talks to raise$2 million to $3 million and has hired two McDonnell-Douglas veterans in its quest to build a drivable prototype by 2008. Ready for take-off, but where? They aim to get the first Transitions to market by the following year, at a retail price of$148,000. The plane is tailor-made, Dietrich says, for the neglected "short-hop market" of 100- to 500-mile jaunts - a market that's only going to grow as airlines abandon low-margin short routes.
http://www.terrafugia.com/
Maybe not as exotic as the jet-man, but pretty cool - and enclosed.
Flying to work - and then driving would be fun.
Related General Discussion News on Phys.org
#### Hurkyl
Staff Emeritus
Gold Member
Bah, nobody on the road pays attention to traffic laws as it is... and you want them the power to fly?
#### neutrino
Bah, nobody on the road pays attention to traffic laws as it is... and you want them the power to fly?
Once they are in air, the road becomes a much safer place (unless one of those flying-machines happens to fall on your car )
#### Ivan Seeking
Staff Emeritus
Gold Member
Watch out for CEOs FUI.
#### Kurdt
Staff Emeritus
Gold Member
Theres only 8 years to go then we'll all be driving cars like those in back to the future. We also have 8 years in which to enjoy 16 new jaws movies
Its not particularly stylish and I'm not sure what market they're aiming for frankly, unless its for people who wish to drive to the airport to take off in their small plane.
#### FredGarvin
Two operative words in that by line...Startup company. Start ups have an enormously difficult time getting a regular aircraft to market let alone something like this. While they'll probably suck off the government under the guise of programs like NASA's GAP program, I'll bet my next paycheck that this company is gone in a year. I must say that it is a lot more stylish and up to date than the aerocar.
#### turbo
Gold Member
It's neat idea, but making that vehicle comply with auto-safety rules while getting it certified as safe to fly will be fraught with interesting twists. One problem regarding road-worthiness is the very small wheels shown in the prototype animation. Highway speeds with small wheels absolutely kill wheel bearings, plus the vehicle will have to be very light in order to fly, making it impossible to handle on the highway with crosswinds. Those folded-up wings would offer crosswinds a LOT of leverage. I'm not trying to be a stick-in-the-mud, but this PhD candidate seems to be ignoring some basic applied engineering problems.
#### interested_learner
They did the same thing in the fifties. There were too many compromises that had to be made. That made the whole project too expensive.
#### Astronuc
Staff Emeritus
Did anyone check the specs - http://www.terrafugia.com/specsheet.pdf [Broken]
I imagine it must pass automobile and aircraft certification.
I don't imagine that it would do much on the highway since one would presumably be flying rather than driving at highway speeds.
1500 ft takeoff distance (so its STOL maybe).
Perhaps he could adapt it to water too! Air - land - sea! :tongue2:
Last edited by a moderator:
Staff Emeritus
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# 2020 AMC 10B Problems/Problem 18
## Problem
An urn contains one red ball and one blue ball. A box of extra red and blue balls lie nearby. George performs the following operation four times: he draws a ball from the urn at random and then takes a ball of the same color from the box and returns those two matching balls to the urn. After the four iterations the urn contains six balls. What is the probability that the urn contains three balls of each color?
$\textbf{(A) } \frac16 \qquad \textbf{(B) }\frac15 \qquad \textbf{(C) } \frac14 \qquad \textbf{(D) } \frac13 \qquad \textbf{(E) } \frac12$
## Solution
Let $R$ denote that George selects a red ball and $B$ that he selects a blue one. Now, in order to get $3$ balls of each color, he needs $2$ more of both $R$ and $B$.
There are 6 cases: $RRBB, RBRB, RBBR, BBRR, BRBR, BRRB$ (we can confirm that there are only $6$ since $\binom{4}{2}=6$). However we can clump $RRBB + BBRR$, $RBRB + BRBR$, and $RBBR + BRRB$ together since they are equivalent by symmetry.
$\textbf{CASE 1: }$ $RRBB$ and $BBRR$
Let's find the probability that he picks the balls in the order of $RRBB$.
The probability that the first ball he picks is red is $\frac{1}{2}$.
Now there are $2$ reds and $1$ blue in the urn. The probability that he picks red again is now $\frac{2}{3}$.
There are $3$ reds and $1$ blue now. The probability that he picks a blue is $\frac{1}{4}$.
Finally, there are $3$ reds and $2$ blues. The probability that he picks a blue is $\frac{2}{5}$.
So the probability that the $RRBB$ case happens is $\frac{1}{2} \cdot \frac{2}{3} \cdot \frac{1}{4} \cdot \frac{2}{5} = \frac{1}{30}$. However, since the $BBRR$ case is the exact same by symmetry, case 1 has a probability of $\frac{1}{30} \cdot 2 = \frac{1}{15}$ chance of happening.
$\textbf{CASE 2: }$ $RBRB$ and $BRBR$
Let's find the probability that he picks the balls in the order of $RBRB$.
The probability that the first ball he picks is red is $\frac{1}{2}$.
Now there are $2$ reds and $1$ blue in the urn. The probability that he picks blue is $\frac{1}{3}$.
There are $2$ reds and $2$ blues now. The probability that he picks a red is $\frac{1}{2}$.
Finally, there are $3$ reds and $2$ blues. The probability that he picks a blue is $\frac{2}{5}$.
So the probability that the $RBRB$ case happens is $\frac{1}{2} \cdot \frac{1}{3} \cdot \frac{1}{2} \cdot \frac{2}{5} = \frac{1}{30}$. However, since the $BRBR$ case is the exact same by symmetry, case 2 has a probability of $\frac{1}{30} \cdot 2 = \frac{1}{15}$ chance of happening.
$\textbf{CASE 3: }$ $RBBR$ and $BRRB$
Let's find the probability that he picks the balls in the order of $RBBR$.
The probability that the first ball he picks is red is $\frac{1}{2}$.
Now there are $2$ reds and $1$ blue in the urn. The probability that he picks blue is $\frac{1}{3}$.
There are $2$ reds and $2$ blues now. The probability that he picks a blue is $\frac{1}{2}$.
Finally, there are $2$ reds and $3$ blues. The probability that he picks a red is $\frac{2}{5}$.
So the probability that the $RBBR$ case happens is $\frac{1}{2} \cdot \frac{1}{3} \cdot \frac{1}{2} \cdot \frac{2}{5} = \frac{1}{30}$. However, since the $BRBR$ case is the exact same by symmetry, case 3 has a probability of $\frac{1}{30} \cdot 2 = \frac{1}{15}$ chance of happening.
Adding up the cases, we have $\frac{1}{15}+\frac{1}{15}+\frac{1}{15}=\boxed{\textbf{(B) }\frac15}$ ~quacker88
## Solution 2
We know that we need to find the probability of adding 2 red and 2 blue balls in some order. There are 6 ways to do this, since there are $\binom{4}{2}=6$ ways to arrange $RRBB$ in some order. We will show that the probability for each of these 6 ways is the same.
We first note that the denominators should be counted by the same number. This number is $2 \cdot 3 \cdot 4 \cdot 5=120$. This is because 2, 3, 4, and 5 represent how many choices there are for the four steps. No matter what the $k-th$ step involves $k+1$ numbers to choose from.
The numerators are the number of successful operations. No matter the order, the first time a red is added will come from 1 choice and the second time will come from 2 choices, since that is how many reds are in the urn originally. The same goes for the blue ones. The numerator must equal $(1 \cdot 2)^2$.
Therefore, the probability for each of the orderings of $RRBB$ is $\frac{4}{120}=\frac{1}{30}$. There are 6 of these, so the total probability is $\boxed{\bf{(B)} \frac{1}{5}}$.
~IceMatrix
|
# Chapter 5 More on thematic maps
## 5.1 Introduction
In this session we are going to discuss some additional features around thematic maps we did not cover in week 3. We are going to discuss how to address some of the problems we confront when we are trying to use use choropleth maps, as well as some alternatives to point based maps. We will also introduce the modifiable area unit problem.
Before we do any of this, we need to load the libraries we will use today:
library(sf)
library(tmap)
library(sp)
library(spdep)
library(DCluster)
library(cartogram)
library(ggplot2)
library(dplyr)
library(janitor)
library(hexbin)
library(ggspatial)
library(geogrid)
Some of the above are new libraries we will use for the first time this week. Remember, if you don’t already have these you will need to install them.
### 5.1.1 Pro-tip: do I need to install this package?
You might have noticed that in your list of available packages you might see more than you remember downloading. The idea of dependencies has come up throughout the semester. Packages have dependencies when their code is dependent on (uses code from) another package. For example, if I write some code that I think will be useful, so I release this in the form of the package “rekaR,” but I use ggplot2 in the code, then ggplot2 will be a dependency of rekaR. As a default, R will install all the dependencies for a package when you install your package. So this way you might end up with some packages there that you didn’t realise you had.
Why am I telling you this? Well you should always check if you have a package, before installing it. And I wanted to share with you some neat code from a Stackoverflow discussion (if you are not yet familiar with Stackoverflow you have not been Google-ing your error messages enough) here to do this. I’ll comment it a bit, so you can follow along what it does but you don’t have to if you don’t want to. This is just an optional extra.
So as a first step, you have to assign a list of all the packages you have to check to an object. Let’s say I tell you that today we will be using the following packaes: “sp,” “rgdal,” “classInt,” “RColorBrewer,” “ggplot2,” “hexbin,” “ggmap,” “XML,” and “dplyr.” Then you can add these to an object called libs, using the c() function:
libs <- c("sf", "tmap", "sp", "spdep", "DCluster", "cartogram")
Now you can run the below bit of code, and you will see in the console an output of what is and isn’t installed, as well as install the packages that are not!
for (x in libs){ #cycle through each item in libs object
if(x %in% rownames(installed.packages()) == FALSE) { #if the package is not installed
print(paste0("installing ", x, "...")) #print a message to tell me
install.packages(x) #and then install the packages
}
else{ #otherwise (if it is installed)
print (paste0(x, " is already installed ")) #print a message to tell me
}
library(x, character.only = TRUE) #and then load the packages
}
## [1] "sf is already installed "
## [1] "tmap is already installed "
## [1] "sp is already installed "
## [1] "spdep is already installed "
## [1] "DCluster is already installed "
## [1] "cartogram is already installed "
As you can see if you read through the comments there, this bit of code checks each package in the list you pass to tbe libs object when you create it, and if it is not installed it installs for you, and if it is, it just loads it for you. It can be a handy bit of code to keep around.
#### 5.1.1.1 Activity 1: Getting some messy data
So far, we’ve really been spoilt by using neat and easy-to-access data typical of ‘western’ countries. This week we will have a little exercise in using data when there may not be such clear ways to access neat and tidy data. Specifically, we’re going to look at some data from India! We’ll be using two datasets:
• A shapefile of India (including boundaries of ‘states’ and ‘districts’)
• District-level data on households and crop yields
First of all, a number of the big universities in the US have repositories (online collections) of GIS data (like shapefiles). There are a few of them that have India shapefiles (Harvard, Stanford) but you need to request access to them for research purposes. If you’re doing your own research and need the shapefile of a country, it’s worth looking on these repositories for it. You can then email them to request access and usually they’ll give access no problem if you’re using it for research. But for now, I’ve already requested access and downloaded the India shapefiles, but please note that these shapefiles are for the purposes of this workshop only. Here’s the link to download the shapefiles: https://www.dropbox.com/sh/6b1wiz3k7v1nl80/AABjYJdC0ETcCNVdbOqbcZxPa?dl=0.
TIP: Use this button to select all files at once, then just hit ‘Download!’
(if you are struggling with this, the files are in a .zip file on Blackboard as well)
You’ll notice that there are different shapefiles there, download them all for now. We will use them to demonstrate a good example of the problems you encounter when researching countries with less infrastructure. The UK has these ’LSOA’s we covered previously, which are areas that don’t change over time. In India, districts (like counties) are merged and split quite frequently and entire states (collections of districts) can merge and split too! So each shapefile we’ve downloaded will have different boundaries and different names for districts - so which one do we use?!
#### 5.1.1.2 Activity 2: Getting some crop data (attributes)
You may be in a situation like the one described above, and you might want to consider for yourself - how can you decide what is the best shapefile to use? Well the answer will really depend on your data set! WHat is it that you want to represent, and what is the best matched shapefile for the job?
One way of deciding is to match each shapefile up with our data (like we did for crime in Manchester before) and checking which shapefile has the most matching district and state names with the dataset. So we’ll start by downloading the dataset.
Great, now let’s read that data into R and have a look!
Just like we read ‘.csv’ files with read.csv, we can read ‘.xlsx’ (Excel) files with the read_xlsx() function from the readxl package:
yield_data <- read_xlsx('data/Bihar.xlsx')
glimpse(yield_data)
## Rows: 688
## Columns: 59
## $STCODE <dbl> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2… ##$ STNAME <chr> "Bihar", "Bihar", "Bihar", "Bihar", "Bihar", "Bihar", "Bihar"…
## $DIST <dbl> 901, 901, 901, 901, 901, 901, 901, 901, 901, 901, 901, 901, 9… ##$ DISTNAME <chr> "Champaran", "Champaran", "Champaran", "Champaran", "Champara…
## $YEAR <dbl> 1966, 1967, 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1… ##$ RICE_TA <dbl> 389.49, 430.45, 450.45, 467.07, 425.50, 447.35, 435.38, 433.3…
## $RICE_TQ <dbl> 159.79, 338.03, 371.31, 286.41, 346.06, 373.39, 358.86, 322.5… ##$ WHT_TA <dbl> 76.45, 98.85, 113.13, 131.65, 131.65, 140.52, 306.58, 129.65,…
## $WHT_TQ <dbl> 41.47, 84.97, 108.83, 159.96, 142.44, 229.13, 328.86, 257.18,… ##$ SORG_KA <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.01, 0.02, 0.00, 0.00, 0.02, 0…
## $SORG_KQ <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.01, 0.00, 0.00, 0.01, 0… ##$ SORG_RA <dbl> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0…
## $SORG_RQ <dbl> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0… ##$ SORG_TA <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.01, 0.02, 0.00, 0.00, 0.02, 0…
## $SORG_TQ <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.01, 0.00, 0.00, 0.01, 0… ##$ PMLT_TA <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.07, 0.07, 0.07, 0.07, 0.14, -…
## $PMLT_TQ <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.03, 0.04, 0.02, 0.03, 0.08, 0… ##$ MAIZ_TA <dbl> 33.56, 43.37, 42.01, 41.80, 44.71, 36.64, 39.89, 44.81, 38.19…
## $MAIZ_TQ <dbl> 22.18, 37.56, 33.87, 28.77, 52.13, 17.61, 58.23, 46.04, 27.10… ##$ FMLT_TA <dbl> 1.65, 1.82, 1.60, 1.56, 1.48, 1.28, 1.60, 1.25, 1.28, 1.67, 1…
## $FMLT_TQ <dbl> 0.61, 0.99, 0.56, 0.46, 0.85, 0.60, 0.92, 0.79, 0.62, 0.62, 1… ##$ BRLY_TA <dbl> 71.94, 73.87, 60.16, 54.02, 45.74, 39.25, 32.00, 34.79, 34.00…
## $BRLY_TQ <dbl> 28.53, 47.83, 32.78, 29.92, 31.88, 32.38, 19.30, 15.84, 27.18… ##$ CERL_TA <dbl> 582.15, 666.16, 679.80, 708.12, 718.94, 740.40, 878.08, 702.4…
## $CERL_TQ <dbl> -1.00, -1.00, -1.00, -1.00, -1.00, 697.53, 803.27, 671.87, 63… ##$ CPEA_TA <dbl> 8.29, 8.49, 6.10, 6.10, 3.71, 3.29, 4.17, 3.13, 2.65, 2.06, 1…
## $CPEA_TQ <dbl> 4.11, 4.03, 2.59, 2.56, 1.40, 1.56, 2.08, 1.78, 1.85, 1.12, 0… ##$ PPEA_TA <dbl> 9.55, 11.29, 10.51, 10.51, 10.29, 8.93, 8.71, 7.56, 7.01, 6.1…
## $PPEA_TQ <dbl> 6.53, 11.43, 10.57, 10.57, 6.90, 8.83, 9.57, 5.03, 5.64, 6.12… ##$ MPUL_TA <dbl> 63.32, 61.15, 56.50, 52.53, 50.19, 53.93, 149.34, -1.00, 47.5…
## $PULS_TA <dbl> 81.16, 80.93, 73.11, 69.14, 64.19, 66.16, 162.22, -1.00, 57.1… ##$ PULS_TQ <dbl> -1.00, -1.00, -1.00, -1.00, -1.00, 34.15, 26.57, 21.64, 27.10…
## $GNUT_TA <dbl> 0.05, 0.08, 0.07, 0.03, 0.01, 0.02, 0.09, 0.03, 0.07, 0.03, 0… ##$ GNUT_TQ <dbl> 0.03, 0.07, 0.03, 0.02, 0.03, 0.02, 0.07, 0.02, 0.07, 0.03, 0…
## $SESA_TA <dbl> 0.99, 1.03, 1.77, 1.89, 1.01, 1.07, 1.42, 1.59, 1.20, 1.11, 1… ##$ SESA_TQ <dbl> 0.33, 0.39, 0.45, 0.60, 0.39, 0.54, 0.62, 0.59, 0.40, 0.24, 0…
## $RM_TA <dbl> 8.17, 8.94, 10.27, 10.98, 10.98, 10.73, 10.60, 8.00, 9.42, 8.… ##$ RM_TQ <dbl> 2.57, 4.97, 4.48, 7.27, 7.28, 6.86, 6.16, 4.04, 4.87, 6.98, 7…
## $SAFF_TA <dbl> 0.01, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0… ##$ SAFF_TQ <dbl> -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -…
## $CAST_TA <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.16, 0.06, -1.00, … ##$ CAST_TQ <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.10, 0.04, -1.00, …
## $LINS_TA <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 8.13, 9.32, -1.00, … ##$ LINS_TQ <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 5.21, 4.37, -1.00, …
## $SUNF_TA <dbl> 0.00, 0.00, 0.00, 0.12, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0… ##$ SUNF_TQ <dbl> 0.00, 0.00, 0.00, 0.06, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0…
## $SOYA_TA <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0… ##$ SOYA_TQ <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0…
## $OILS_TA <dbl> 19.33, 20.51, 22.06, 21.67, 20.44, 20.51, 19.75, 18.65, 19.90… ##$ OILS_TQ <dbl> -1.00, -1.00, -1.00, -1.00, -1.00, -1.00, -1.00, 9.93, 9.66, …
## $SCAN_TA <dbl> 46.20, 38.05, 46.11, 52.69, 56.30, 51.10, 50.20, 48.43, 50.54… ##$ SGUR_TQ <dbl> 150.80, 127.60, 193.30, 216.80, 251.50, 183.90, 200.70, 165.1…
## $COTN_TA <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0… ##$ COTN_TQ <dbl> 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.00, 0.25, 0.00, 0.00, 0…
## $FRUT_TA <dbl> 17.14, 16.09, 17.35, 16.09, 18.38, 18.08, 16.63, 17.42, 17.34… ##$ VEGT_TA <dbl> 16.58, 18.91, 21.81, 19.39, 21.10, 20.50, 21.76, 20.26, 21.55…
## $TFV_TA <dbl> 33.72, 35.00, 39.16, 35.48, 39.48, 38.58, 38.39, 37.68, 38.89… ##$ POTA_TA <dbl> 4.28, 4.79, 7.04, 7.10, 7.30, 6.96, 7.66, 7.23, 8.01, 8.36, 8…
## $ONIO_TA <dbl> 1.22, 1.39, 1.69, 1.63, 1.78, 1.56, 1.76, 1.74, 1.64, 1.95, 1… After looking at the yield data, you can see it’s quite massive! Each column represents the production in weight (’_TQ’ columns) and the area farmed (’_TA’ columns) for each crop, per district, per year. That’s too much information for us! We just want rice production and area, so we’ll use the ‘select’ function to just pick the columns we want: names of states and districts, the year, and the rice information. yield_data <- yield_data %>% dplyr::select(STNAME, DISTNAME, YEAR, RICE_TA, RICE_TQ) #### 5.1.1.3 Activity 3: Comparing shapefiles Now we’ve read in our rice yield data, we can test which shapefile will work best with the district names in our yield data. For this, we’ll use a basic ‘for’ loop which will test each shapefile (1951/61/71/81/91/2001) individually. This will show us which shapefile has the most matching district names (across India) with the yield data. Don’t worry about loops in R, they’re something you can learn if you’re interested but otherwise you can copy + paste the code below - so long as you understand what it’s doing overall. Chris’ advanced R will cover loops this week. N.B. You may need to change ‘shapefile_location <-’ to tell R where you have saved your shapefiles! # Make a list of years between 1951 and 2001 at intervals every 10 years and store them as # characters instead of numbers (so we can use them as names of files in the loop) shapefile_years <- lapply(seq(1951, 2001, 10), as.character) # Get a list of district names in the yield data to compare to each shapefile yield_dist_names <- make_clean_names(unique(yield_data$DISTNAME))
# Prepare an output variable
district_match_results <- tibble(shapefile_year = character(),
district_match_percent = numeric())
# Loop through each item in the 'shapefile_years' list and call each item 'each_year'
for (each_year in shapefile_years){
# Change this if you need to, give the path to the directory with your shapefiles in
shapefile_location <- 'data/IndiaBoundaryData/'
# Get lists of each shapefile's district names
shpfile_dist_names <- make_clean_names(unique(each_shapefile$NAME)) # Get the percentage of matching district names between yield data and each shpfile dist_match <- round(length(dplyr::intersect(yield_dist_names, shpfile_dist_names))/length(yield_dist_names)*100, 0) # Store results in output variable district_match_results <- bind_rows(district_match_results, tibble(shapefile_year = each_year, district_match_percent = dist_match)) } ## Reading layer 1951' from data source /Users/reka/Desktop/crime_mapping_textbook/data/IndiaBoundaryData/1951.shp' using driver ESRI Shapefile' ## Simple feature collection with 316 features and 9 fields ## Geometry type: MULTIPOLYGON ## Dimension: XY ## Bounding box: xmin: 68.11009 ymin: 6.755698 xmax: 97.4091 ymax: 37.0503 ## Geodetic CRS: WGS 84 ## Reading layer 1961' from data source /Users/reka/Desktop/crime_mapping_textbook/data/IndiaBoundaryData/1961.shp' using driver ESRI Shapefile' ## Simple feature collection with 341 features and 50 fields ## Geometry type: MULTIPOLYGON ## Dimension: XY ## Bounding box: xmin: 68.11009 ymin: 6.755698 xmax: 97.4091 ymax: 37.0503 ## Geodetic CRS: WGS 84 ## Reading layer 1971' from data source /Users/reka/Desktop/crime_mapping_textbook/data/IndiaBoundaryData/1971.shp' using driver ESRI Shapefile' ## Simple feature collection with 360 features and 70 fields ## Geometry type: MULTIPOLYGON ## Dimension: XY ## Bounding box: xmin: 68.11009 ymin: 6.755698 xmax: 97.4091 ymax: 37.0503 ## Geodetic CRS: WGS 84 ## Reading layer 1981' from data source /Users/reka/Desktop/crime_mapping_textbook/data/IndiaBoundaryData/1981.shp' using driver ESRI Shapefile' ## Simple feature collection with 426 features and 59 fields ## Geometry type: MULTIPOLYGON ## Dimension: XY ## Bounding box: xmin: 68.11009 ymin: 6.755698 xmax: 97.4091 ymax: 37.0503 ## Geodetic CRS: WGS 84 ## Reading layer 1991' from data source /Users/reka/Desktop/crime_mapping_textbook/data/IndiaBoundaryData/1991.shp' using driver ESRI Shapefile' ## Simple feature collection with 468 features and 144 fields ## Geometry type: MULTIPOLYGON ## Dimension: XY ## Bounding box: xmin: 68.11009 ymin: 6.755698 xmax: 97.4091 ymax: 37.0503 ## Geodetic CRS: WGS 84 ## Reading layer 2001' from data source /Users/reka/Desktop/crime_mapping_textbook/data/IndiaBoundaryData/2001.shp' using driver ESRI Shapefile' ## Simple feature collection with 595 features and 170 fields ## Geometry type: MULTIPOLYGON ## Dimension: XY ## Bounding box: xmin: 68.11009 ymin: 6.755698 xmax: 97.4091 ymax: 37.0503 ## Geodetic CRS: WGS 84 And now to check the output to see which shapefile has the highest proportion of district name matches: print(district_match_results) ## # A tibble: 6 x 2 ## shapefile_year district_match_percent ## <chr> <dbl> ## 1 1951 72 ## 2 1961 72 ## 3 1971 89 ## 4 1981 61 ## 5 1991 61 ## 6 2001 56 # And plot it with ggplot ggplot(district_match_results) + geom_bar(aes(x = shapefile_year, y = district_match_percent), stat = 'identity') So, before continuing you should look at the table and graph you’ve just made and decide which shapefile we should use now. Which one will be the best for representing your attribute table? #### 5.1.1.4 Activity 4: Joining datasets One last thing before we can continue mapping - joining our yield and shapefile datasets together! Some name cleaning is required first, to make sure they match up. Hopefully you found before that the 1971 shapefile has the highest percentage of district name matches with our yield data - so we’ll read that one in now: # Read in the 1971 shapefile shapefile <- st_read('data/IndiaBoundaryData/1971.shp') ## Reading layer 1971' from data source /Users/reka/Desktop/crime_mapping_textbook/data/IndiaBoundaryData/1971.shp' using driver ESRI Shapefile' ## Simple feature collection with 360 features and 70 fields ## Geometry type: MULTIPOLYGON ## Dimension: XY ## Bounding box: xmin: 68.11009 ymin: 6.755698 xmax: 97.4091 ymax: 37.0503 ## Geodetic CRS: WGS 84 # Clean the shapefile state and district names shapefile$NAME <- make_clean_names(shapefile$NAME) shapefile$STATE_UT <- tolower(shapefile$STATE_UT) # Clean the yield data's state and district names in the same way yield_data$DISTNAME <- gsub(' ', '_', tolower(yield_data$DISTNAME)) yield_data$STNAME <- tolower(yield_data$STNAME) # Join the two datasets together, the 'by' argument in right_join describes which columns # are equivalent in each dataset district_yields <- shapefile %>% right_join(yield_data, by = c('NAME' = 'DISTNAME', 'STATE_UT' = 'STNAME')) %>% dplyr::select(YEAR, NAME, STATE_UT, RICE_TA, RICE_TQ) %>% # 'select' only selects the columns we're interested in (specify select from dplyr!) mutate(rice_yield = RICE_TQ/RICE_TA) %>% rename(district = NAME, state = STATE_UT) # Check output head(district_yields) ## Simple feature collection with 6 features and 6 fields ## Geometry type: MULTIPOLYGON ## Dimension: XY ## Bounding box: xmin: 84.68945 ymin: 24.95576 xmax: 86.07065 ymax: 25.73259 ## Geodetic CRS: WGS 84 ## YEAR district state RICE_TA RICE_TQ rice_yield geometry ## 1 1966 patna bihar 138.92 16.21 0.1166859 MULTIPOLYGON (((85.02075 25... ## 2 1967 patna bihar 220.10 211.13 0.9592458 MULTIPOLYGON (((85.02075 25... ## 3 1968 patna bihar 263.87 231.91 0.8788798 MULTIPOLYGON (((85.02075 25... ## 4 1969 patna bihar 262.85 178.89 0.6805783 MULTIPOLYGON (((85.02075 25... ## 5 1970 patna bihar 229.71 231.55 1.0080101 MULTIPOLYGON (((85.02075 25... ## 6 1971 patna bihar 189.13 320.56 1.6949188 MULTIPOLYGON (((85.02075 25... ## 5.2 Mapping rates, learning from yield mapping In previous sessions we discussed how to map rates. It seems a fairly straightforward issue, you calculate a rate by dividing your numerator (eg: number of crimes or rice production) by your denominator (eg: daytime population or farming area). You get your variable with the relevant rate and you map it using a choropleth map. However, things are not always that simple. Rates are funny animals. This popped up in your preparation material as the problem “insensitivity to sample size” and we will demonstrate in the next activity. ### 5.2.1 Activity 4: The case of Saharsa Let’s look at our yield data, here yield means the amount of rice produced (in tonnes, 1 tonne = 1000kg) per hectare (a square of land with 100 metre-long sides) of rice farmland. summary(district_yields$rice_yield)
## Min. 1st Qu. Median Mean 3rd Qu. Max.
## 0.0000 0.7690 0.9935 1.0560 1.2223 5.5423
We can see that the district with the highest rice production rate in 1971 had a rate of 55,423 tonnes of rice per 100,000 individuals. That’s really high, over 500kg of rice per person! Where is that place? I can tell you it’s a place call Saharsa. Check it out:
# This will show us the row with the highest yield
district_yields %>% filter(rice_yield == max(rice_yield))
## Simple feature collection with 1 feature and 6 fields
## Geometry type: MULTIPOLYGON
## Dimension: XY
## Bounding box: xmin: 86.31699 ymin: 25.44194 xmax: 87.12818 ymax: 26.5624
## Geodetic CRS: WGS 84
## YEAR district state RICE_TA RICE_TQ rice_yield geometry
## 1 1971 saharsa bihar 204.86 1135.4 5.542322 MULTIPOLYGON (((87.04089 26...
# Subset the 'Saharsa' district data
saharsa <- subset(district_yields, district == "saharsa")
Saharsa district in Bihar, India is known for high quality corn, much of which is exported out here to the UK! But Saharsa isn’t particularly known for its great rice production. So, what’s going on here? Why do we have a high production rate (yield) in Saharsa that makes it look like the rice capital of India?
Well, we can see from the output above that this happened in 1971 in Saharsa, so let’s map out the yields of all districts in Bihar in 1971 to investigate:
bihar_1971 <- filter(district_yields, YEAR == '1971')
tm_shape(bihar_1971)+
tm_fill('rice_yield')
## Warning: The shape bihar_1971 contains empty units.
Saharsa is the darkly-shaded district in the top-right, it stands out massively from all other districts! Let’s plot the following year, 1972, for comparison:
bihar_1972 <- filter(district_yields, YEAR == '1972')
tm_shape(bihar_1972)+
tm_fill('rice_yield')
## Warning: The shape bihar_1972 contains empty units.
Now Saharsa is in the lowest yield bracket - 0.2 to 0.4, pretty far off 5.5! Why does its yield value swing so far?
print(filter(district_yields, district == 'saharsa', YEAR == '1971') %>% pull(RICE_TA))
## [1] 204.86
area_comparison <- district_yields %>%
group_by(district) %>%
summarise(mean_area = mean(RICE_TA)) %>%
dplyr::select(district, mean_area)
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
## although coordinates are longitude/latitude, st_union assumes that they are planar
print(area_comparison)
## Simple feature collection with 18 features and 2 fields (with 2 geometries empty)
## Geometry type: MULTIPOLYGON
## Dimension: XY
## Bounding box: xmin: 83.32587 ymin: 21.9699 xmax: 88.29327 ymax: 27.51885
## Geodetic CRS: WGS 84
## # A tibble: 18 x 3
## district mean_area geometry
## <chr> <dbl> <MULTIPOLYGON [°]>
## 1 bhagalpur 151. (((87.1004 25.49808, 87.10085 25.49706, 87.10083 25.…
## 2 champaran 434. (((84.12354 27.51036, 84.12808 27.50942, 84.13081 27…
## 3 darbhanga 361. (((86.07361 26.65632, 86.07475 26.65469, 86.07544 26…
## 4 dhanbad 52.0 (((86.3877 24.05193, 86.38903 24.04741, 86.38946 24.…
## 5 gaya 439. (((85.00572 25.29162, 85.00678 25.29108, 85.00809 25…
## 6 hazaribag 188. (((85.75342 24.81269, 85.7547 24.81224, 85.75471 24.…
## 7 monghyar 180. (((86.13477 25.76138, 86.1353 25.7611, 86.13603 25.7…
## 8 muzaffarpur 324. (((85.66128 26.84723, 85.67135 26.84497, 85.67583 26…
## 9 muzzafarpur 346. EMPTY
## 10 palamau 79.0 (((84.02914 24.62704, 84.03024 24.62684, 84.03216 24…
## 11 patna 217. (((85.02075 25.73202, 85.02852 25.73189, 85.03005 25…
## 12 purnia 478. (((87.06237 26.58623, 87.06268 26.58621, 87.06619 26…
## 13 ranchi 399. (((84.99077 23.69956, 84.99183 23.69665, 84.99219 23…
## 14 saharsa 186. (((87.04089 26.56165, 87.04169 26.56154, 87.04329 26…
## 15 santhal_para… 354. EMPTY
## 16 saran 261. (((84.09505 26.6367, 84.09814 26.63578, 84.09865 26.…
## 17 shahabad 476. (((84.69971 25.75515, 84.7004 25.7505, 84.7004 25.74…
## 18 singhbhum 289. (((85.8843 23.16295, 85.88689 23.16146, 85.88792 23.…
Although it doesn’t have the smallest rice farmland area, Saharsa’s rice land is pretty small. Remember that the rate is simply dividing the number of relevant events (rice production) by the exposure variable (in this case area of rice farmland). Most times Saharsa has very low yields ( < 1 tonne per hectare):
print(filter(district_yields, district == 'saharsa'))
## Simple feature collection with 44 features and 6 fields
## Geometry type: MULTIPOLYGON
## Dimension: XY
## Bounding box: xmin: 86.31699 ymin: 25.44194 xmax: 87.12818 ymax: 26.5624
## Geodetic CRS: WGS 84
## First 10 features:
## YEAR district state RICE_TA RICE_TQ rice_yield
## 1 1966 saharsa bihar 126.51 41.03 0.32432219
## 2 1967 saharsa bihar 190.54 143.14 0.75123334
## 3 1968 saharsa bihar 200.53 157.23 0.78407221
## 4 1969 saharsa bihar 209.53 121.28 0.57881926
## 5 1970 saharsa bihar 199.40 136.47 0.68440321
## 6 1971 saharsa bihar 204.86 1135.40 5.54232159
## 7 1972 saharsa bihar 166.16 85.27 0.51318007
## 8 1973 saharsa bihar 167.32 107.88 0.64475257
## 9 1974 saharsa bihar 192.74 147.14 0.76341185
## 10 1975 saharsa bihar 195.28 16.41 0.08403318
## geometry
## 1 MULTIPOLYGON (((87.04089 26...
## 2 MULTIPOLYGON (((87.04089 26...
## 3 MULTIPOLYGON (((87.04089 26...
## 4 MULTIPOLYGON (((87.04089 26...
## 5 MULTIPOLYGON (((87.04089 26...
## 6 MULTIPOLYGON (((87.04089 26...
## 7 MULTIPOLYGON (((87.04089 26...
## 8 MULTIPOLYGON (((87.04089 26...
## 9 MULTIPOLYGON (((87.04089 26...
## 10 MULTIPOLYGON (((87.04089 26...
Saharsa’s rice production is around 130 tonnes in most years. But it only takes one good year of rice growth and, bang, it goes to the top of the league. So a standard map of rates is bound to be noisy. There is the instability that is introduced by virtue of having areas that may be sparsely populated and in which one single event, like in this case a bumper crop, will produce a very noticeable change in the rate. In fact, if you look at the counties with the highest yields in the yield dataset you will notice all of them are places like Saharsa, areas that have small areas of rice farmland (RICE_TA). So they have high yields not because they produce massive amounts of rice, but because of the instability of rates.
This is a problem that was first noted by epidemiologists doing disease mapping. But a number of other disciplines have now noted this and used some of the approaches developed by public health researchers that confronted this problem when producing maps of disease (techniques and approaches used by spatial epidemiologists are very similar to those used by criminologists -in case you ever think of changing careers or need inspiration for how to solve a crime analysis problem).
### 5.2.2 Activity 5: Smoothing as a way to address insensitivity to sample size
One way of dealing with this is by smoothing the rates. This basically as the word implies aims for a smoother representation that avoids hard spikes associated with random noise. There are different ways of doing that. Some ways use a non-spatial approach to smoothing, using something called a empirical bayesian smoother. How does this work? This approach takes the raw rates and tries to “shrink” them towards the overall average.
The formal logic behind the idea of smoothing is situated in a Bayesian framework, in which the distribution of a random variable is updated after observing data. In the Empirical Bayes approach, values for $$\alpha$$ and $$\beta$$ of the prior Gamma distribution are estimated from the actual data. The smoothed rate is then expressed as a weighted average of the crude rate and the prior estimate.
What does this mean? Essentially, we compute a weighted average between the raw rate for each area and the global average across all areas, with weights proportional to the underlying population at risk. What this procedure does is to have the rates of smaller areas (those with a small population at risk) to have their rates adjusted considerably (brought closer to the global average), whereas the rates for the larger areas will barely change.
Here we are going to introduce the approach implemented in DCluster, a package developed for epidemiological research and detection of clusters of disease.
Specifically, we use the empbaysmooth(Observed, Expected) function, where we specify two values, the expected value (the global average) and the observed value (the rate we actually see).
(note for the next part iwht neighbours to work we have to remove the one polygon with the empty geometry with st_is_empty()
bihar_1971 <- bihar_1971 %>% filter(!st_is_empty(.))
res <- empbaysmooth(bihar_1971$rice_yield, bihar_1971$RICE_TA*(sum(bihar_1971$rice_yield)/sum(bihar_1971$RICE_TA)))
In the new object we generate, which is a list, you have an element which contains the computed rates. We can add those to our dataset:
bihar_1971$rice_yieldEBS <- res$smthrr
Alternatively instead of shrinking to the global rate, we can shrink to a rate based on the neighbours of each county. In this case, instead of shrinking to a global rate, we shrink to a local rate. We then may be able to take unobserved heterogeneity into account. For this we need the list of neighbours (we will discuss this code in a later session, so for now just trust us we are computing the rate of the areas that surround each counry):
bihar_1971 <- bihar_1971 %>% mutate(INTERSECT = st_intersects(.))
## although coordinates are longitude/latitude, st_intersects assumes that they are planar
as.nb.sgbp <- function(x, ...) {
attrs <- attributes(x)
x <- lapply(x, function(i) { if(length(i) == 0L) 0L else i } )
attributes(x) <- attrs
class(x) <- "nb"
x
}
w_sf <- as.nb.sgbp(bihar_1971$INTERSECT) And now that we have the list of neighbours, we can use the EBlocal() function, and here specofy the count of cases (observed), the population at risk (or rice_TA in the case of our crop yields) and then finally the neighbours list we just created above (w_sf): eb2 <- EBlocal(bihar_1971$rice_yield, bihar_1971$RICE_TA, w_sf) bihar_1971$rice_yieldEBSL <- eb2$est bihar_1971$INTERSECT <- NULL
We can now plot the maps and compare them :
current_style <- tmap_style("col_blind")
## tmap style set to "col_blind"
## other available styles are: "white", "gray", "natural", "cobalt", "albatross", "beaver", "bw", "classic", "watercolor"
map1 <- tm_shape(bihar_1971) +
tm_fill("rice_yield", style="quantile", title = "Raw rate", palette = "Reds") +
tm_layout(legend.position = c("left", "bottom"),
legend.title.size = 0.8,
legend.text.size = 0.5)
map2<- tm_shape(bihar_1971) +
tm_fill("rice_yieldEBS", style="quantile", title = "EB Smooth", palette = "Reds") +
tm_layout(legend.position = c("left", "bottom"),
legend.title.size = 0.8,
legend.text.size = 0.5)
map3<- tm_shape(bihar_1971) +
tm_fill("rice_yieldEBSL", style="quantile", title = "Local Smooth", palette = "Reds") +
tm_layout(legend.position = c("left", "bottom"),
legend.title.size = 0.8,
legend.text.size = 0.5)
tmap_arrange(map1, map2, map3)
Notice that the quantiles are not the same, so that will make your comparison difficult!
## 5.3 Binning points
We’re going to move away from area-level data now, and go back to point-level data.
In GIS it is often difficult to present point-based data because in many instances there are several different points and data symbologies that need to be shown. As the number of different data points grows they can become complicated to interpret and manage which can result in convoluted and sometimes inaccurate maps. This becomes an even larger problem in web maps that are able to be depicted at different scales because smaller scale maps need to show more area and more data. This makes the maps convoluted if multiple data points are included.
In many maps there are so many data points included that little can be interpreted from them. In order to reduce congestion on maps many GIS users and cartographers have turned to a process known as binning.
Binning is defined as the process of grouping pairs of locations based on their distance from one another. These points can then be grouped as categories to make less complex and more meaningful maps.
Researchers and practitioners often require a way to systematically divide a region into equal-sized portions. As well as making maps with many points easier to read, binning data into regions can help identify spatial influence of neighbourhoods, and can be an essential step in developing systematic sampling designs.
This approach to binning generates an array of repeating shapes over a user-specified area. These shapes can be hexagons, squares, rectangles, triangles, circles or points, and they can be generated with any directional orientation.
### 5.3.1 The Binning Process
Binning is a data modification technique that changes the way data is shown at small scales. It is done in the pre-processing stage of data analysis to convert the original data values into a range of small intervals, known as a bin. These bins are then replaced by a value that is representative of the interval to reduce the number of data points.
Spatial binning (also called spatial discretization) discretizes the location values into a small number of groups associated with geographical areas or shapes. The assignment of a location to a group can be done by any of the following methods: - Using the coordinates of the point to identify which “bin” it belongs to. - Using a common variable in the attribute table of the bin and the point layers.
### 5.3.2 Different Binning Techniques
Binning itself is a general term used to describe the grouping of a dataset’s values into smaller groups (Johnson, 2011). The bins can be based on a variety of factors and attributes such as spatial and temporal and can thus be used for many different projects.
#### 5.3.2.1 Choropleth maps
You might be thinkging, “grouping points into a larger spatial unit, haven’t we already done this when making choropleth maps?” In a way you are right. Choropleth maps are another type of map to that uses binning. Proportional symbol and choropleth maps group similar data points together to show a range of data instead of many individual points. We’ve covered this extensively, and is generally the best approch to consider spatial grouping of your point variables, because the polygons (shapes) to which you are aggregating your points are meaningful. You can group into LSOAs because you want to show variation in neighbourhoods. Or you can group into police force areas because you want to look at differences between those units of analysis. But sometimes there is just not a geography present to meet your needs.
Let’s say you are conducting some days of action in Manchester city centre, focusing on antisocial behaviour. You are going to put up some information booths and staff them with officers to engage with the local population about antiscoail behaviour. For these to be most effective, as an analyst you decide that they should go into the areas with the highest count of antisocial beaviour. You want to be very specific about where you put these as well, and so LSOA level would be too broad, you want to zoom in more. One approach can be to split central Manchester into some smaller polygons, and just calculate the number of antisocial behaviour incidents recorded in each. That way you can then decide to put your information booths somewhere inside the top 5 highest count bins.
#### 5.3.2.2 Rectangular binning
The aggregation of incident point data to regularly shaped grids is used for many reasons such as normalizing geography for mapping or to mitigate the issues of using irregularly shaped polygons created arbitrarily (such as county boundaries or block groups that have been created from a political process). Regularly shaped grids can only be comprised of equilateral triangles, squares, or hexagons, as these three polygon shapes are the only three that can tessellate (repeating the same shape over and over again, edge to edge, to cover an area without gaps or overlaps) to create an evenly spaced grid.
Rectangular binning is the simplest binning method and as such it heavily used. However, there are some reasons why rectangular bins are less preferable over hexagonal bins. Before we cover this, let’s have a look at hexagonal bins.
#### 5.3.2.3 Hexagonal binning
In many applications binning is done using a technique called hexagonal binning. This technique uses hexagon shapes to create a grid of points and develops a spatial histogram that shows different data points as a range or group of pairs with common distances and directions. In hexagonal binning the number of points falling within a particular rectangular or hexagon in a gridded surface is what makes the different colors to easily visualize data (Smith, 2012). Hexagonnal binning was first developed in 1987 and today “hexbinning” is conducted by laying a hexagonal grid on top of 2-dimensional data (Johnson, 2011). Once this is done users can conduct data point counts to determine the number of points for each hexagon (Johnson, 2011). The bins are then symbolized differently to show meaningful patterns in the data.
#### 5.3.2.4 Activity 6: Hexbinning
So how can we use hexbinning to solve our antisocial behaviour days of action task? Well let’s say we split Manchester city centre into hexagons, and count the number of antisocial behaviour instances in these. We can then identify the top hexagons, and locate our booths somewhere within these.
Also let’s get some data. You could go and get this data yourself from police.uk, we’ve been through all the steps for downloading data from there a few times now. But for now, I have a tidied set of data ready for you. This data is one year’s worth of antisocial behaviour from the police.uk data, from May 2016 to May 2017, for the borough of Manchester.
We can take our GMP crimes data, and select only the cases from ASB using the crime.type variable. If you want, however, I have already done this, so you can also download from my dropbox using the link here, (or get it from Blackboard):
manchester_asb <- read_csv("https://www.dropbox.com/s/4tk0aps3jfd9nh4/manchester_asb.csv?dl=1")
## Warning: Missing column names filled in: 'X1' [1]
##
## ── Column specification ────────────────────────────────────────────────────────
## cols(
## X1 = col_double(),
## X = col_double(),
## Crime.ID = col_logical(),
## Month = col_character(),
## Reported.by = col_character(),
## Falls.within = col_character(),
## Longitude = col_double(),
## Latitude = col_double(),
## Location = col_character(),
## LSOA.code = col_character(),
## LSOA.name = col_character(),
## Crime.type = col_character(),
## Last.outcome.category = col_logical(),
## Context = col_logical(),
## borough = col_character()
## )
This is currently just a text dataframe, so we need to let R know that actually this is a spatial object, who’s geometry can be find in its longitude and latitude coordinates. As we have long/lat we can assure it’s in WGS 84 projection.
ma_spatial <- st_as_sf(manchester_asb, coords = c("Longitude", "Latitude"),
crs = 4326, agr = "constant")
Now one thing that this does is it consumes our Long and Lat columns into a geometry attribute. This is generally OK, but for the binning we will do, we would like to have them as separate coordinates. To do this, we can use a bespoke function, sfc_as_cols() created by Josh M. London in response to this issue opened on github for the sf package. To create this function here, run the below code:
sfc_as_cols <- function(x, names = c("x","y")) {
stopifnot(inherits(x,"sf") && inherits(sf::st_geometry(x),"sfc_POINT"))
ret <- sf::st_coordinates(x)
ret <- tibble::as_tibble(ret)
stopifnot(length(names) == ncol(ret))
x <- x[ , !names(x) %in% names]
ret <- setNames(ret,names)
dplyr::bind_cols(x,ret)
}
As we are not covering making your own function much here, don’t worry too much about the above code, but if you’re curious, raise your hand in the labs and we can come around and talk through it.
Now finally, let’s use this function we just created to extract the coords to some columns. So in this function, we have to pass as parameters the name of the dataframe, ma_spatial in our case, and also what we want the columnd to be called in a concatenated list (created with the c() function). Let’s call these “lng” and “lat”:
ma_spatial <- sfc_as_cols(ma_spatial, c("lng", "lat"))
As a first step, we can plot asb in the borough of Manchester using simple ggplot! Remember the data visualisation session from weeks ago? We discussed how ggplot is such a great tool for building visualisations, because you can apply whatever geometry best suits your data. So for us to just have a look at the hexbinned version of our point data of antisocial behaviour, we can use the stat_binhex() function. We can also recreate the thematic map element, as we can use the frequency of points in each hex to shade each hexbin from white (least number of incidents) to red (most nuber of incidents).
So let’s have a go:
ggplot(ma_spatial, aes(lng, lat)) + #define data and variables for x and y axes
stat_binhex() + #add binhex layer (hexbin)
scale_fill_gradientn(colours = c("white","red"), name = "Frequency") #add shading based on number of ASB incidents
Neat, but doesn’t quite tell us where that really dark hexbon actually is. So it would be much better if we could do this with a basemap as the backrgound, rather than our grey ggplot theme.
Now, we can apply the same code as we used above, for the ggplot, to this ggmap, to add our hexbins on top of this basemap:
ggplot(ma_spatial, aes(x = lng, y = lat)) +
annotation_map_tile() +
stat_binhex(alpha=0.7) + #add binhex layer (hexbin)
scale_fill_gradientn(colours = c("white","red"), name = "Frequency") #add shading based on number of ASB incidents
## Zoom: 10
Now this should give you some more context! Woo!
So I mentioned we’d go over some reasons why you should consider aggregating into a hexagon grid rather than other shape:
• Hexagons reduce sampling bias due to edge effects of the grid shape. The edge effects of bounded space refers to the problem of truncated data that can skew the results of subsequent analyses (we’ll get to this in the next section). This is related to the low perimeter-to-area ratio of the shape of the hexagon. A circle has the lowest ratio but cannot tessellate to form a continuous grid. Hexagons are the most circular-shaped polygon that can tessellate to form an evenly spaced grid.
• This circularity of a hexagon grid allows it to represent curves in the patterns of your data more naturally than square grids.
• When comparing polygons with equal areas, the more similar to a circle the polygon is, the closer to the centroid the points near the border are (especially points near the vertices). This means that any point inside a hexagon is closer to the centroid of the hexagon than any given point in an equal-area square or triangle would be (this is due to the more acute angles of the square and triangle versus the hexagon).
• Hexagons are preferable when your analysis includes aspects of connectivity or movement paths. Due to the linear nature of rectangles, fishnet grids can draw our eyes to the straight, unbroken, parallel lines which may inhibit the underlying patterns in the data. Hexagons tend to break up the lines and allow any curvature of the patterns in the data to be seen more clearly and easily. This breakup of artificial linear patterns also diminishes any orientation bias that can be perceived in fishnet grids.
• If you are working over a large area, a hexagon grid will suffer less distortion due to the curvature of the earth than the shape of a fishnet grid.
• Finding neighbors is more straightforward with a hexagon grid. Since the edge or length of contact is the same on each side, the centroid of each neighbor is equidistant. However, with a fishnet grid, the Queen’s Case (above/below/right/left) neighbor’s centroids are N units away, while the centroids of the diagonal (Rook) neighbors are farther away (exactly the square root of 2 times N units away).
• Since the distance between centroids is the same in all six directions with hexagons, if you are using a distance band to find neighbors or are using the Optimized Hot Spot Analysis, Optimized Outlier Analysis or Create Space Time Cube By Aggregating Points tools, you will have more neighbors included in the calculations for each feature if you are using hexagonal grid as opposed to a fishnet grid.
#### 5.3.2.5 Activity 6: Rectangular binning
Now, to again illustrate the differences of different approaches, let’s see what this map would look like with:
1. rectangular binning:
ggplot(ma_spatial, aes(x = lng, y = lat)) +
annotation_map_tile() +
stat_bin2d(alpha=0.7) +
name = "Frequency")
## Zoom: 10
1. hexagonal binning:
ggplot(ma_spatial, aes(x = lng, y = lat)) +
annotation_map_tile() +
stat_binhex(alpha=0.7) +
name = "Frequency")
## Zoom: 10
1. a simple “heatmap” (we will discuss these more thoroughly next week):
ggplot(ma_spatial, aes(x = lng, y = lat)) +
annotation_map_tile() +
stat_density2d(aes(fill = ..level.., # value corresponding to discretized density estimates
alpha = ..level..),
geom = "polygon") + # creates the bands of differenc colors
## Configure the colors, transparency and panel
name = "Frequency")
## Zoom: 11
Look at the difference between the three maps (hex, rectangle, and density). How would your conclusions change if you were given these maps? Would you make different decisions about where to place your booths for the days of action? Why or why not? Discuss.
### 5.3.3 Multivariate binning
Multivariate binning is another binning method that lets you visualise slightly more complex data. In this method there can be many different variables consisting of different types of data. Like other binning methods the data is typically grouped with the sum or average of the data. Different types of symbology (such as size, shape and color) can also be used to represent this data as well.
We won’t be covering this here but just so you can have a look at some examples here.
### 5.3.4 Benefits of Binning
Because of the plethora of data types available and the wide variety of projects being done in GIS, binning is a popular method for mapping complex data and making it meaningful. Binning is a good option for map makers as well as users because it makes data easy to understand and it can be both static and interactive on many different map scales. If every different point were shown on a map it would have to be a very large scale map to ensure that the data points did not overlap and were easily understood by people using the maps.
According to Kenneth Field, an Esri Research Cartographer, “Data binning is a great alternative for mapping large point-based data sets which allows us to tell a better story without interpolation. Binning is a way of converting point-based data into a regular grid of polygons so that each polygon represents the aggregation of points that fall within it.”
By using binning to create categories of data maps are easier to understand, more accurate and more visually appealing.
Hexbin plots can be viewed as an alternative to scatter plots. The hexagon-shaped bins were introduced to plot densely packed sunflower plots. They can be used to plot scatter plots with high-density data.
## 5.4 A note of caution: MAUP
Now that we’ve shown you how to do a lot of spatial crime analysis, we wanted to close with some words of caution. Remember that everything you’ve learned here are just tools that you will be applying to data you are working with, but it’s up to you, the researcher, the analyst, the domain expert, to apply and use these with careful consideration and cautions. This discussion is very much part of spatial crime analysis, and an important field of thought.
I borrow here from George Renghert and Brian Lockwood:
When spatial analysis of crime is conducted, the analyst should not ignore the spatial units that data are aggregated into and the impact of this choice on the interpretation of findings. Just as several independent variables are considered to determine whether they have statistical significance, a consideration of multiple spatial units of analysis should be made as well, in order to determine whether the choice of aggregation level used in a spatial analysis can result in biased findings.
In particular, they highlight four main issues inherent in most studies of space:
• issues associated with politically bounded units of aggregation,
• edge effects of bounded space
• the modifiable aerial unit problem (MAUP)
• and ways in which the results of statistical analyses can be manipulated by changes in the level of aggregation.
In this lab we will focus on MAUP, but if you are interested in this kind of work, you should definitely read their paper to consider the other issues as well. There are techniques that can be used to alleviate each of the methodological difficulties, and they are described in accessible detail in their paper: Rengert, George F., and Brian Lockwood. “Geographical units of analysis and the analysis of crime.” Putting crime in its place. Springer, New York, NY, 2009. 109-122.
### 5.4.1 What is MAUP?
The Modifiable Areal Unit Problem (MAUP) is an important issue for those who conduct spatial analysis using units of analysis at aggregations higher than incident level. It is one of the better-known problems in geography and spatial analysis. This phenomenon illustrates both the need for considering space in one’s analysis, and the fundamental uncertainties that accompany real-world analysis.
The MAUP is "a problem arising from the imposition of artificial units of spatial reporting on continuous geographical phenomena, leading to artifacts or errors are created when one groups data into units for analysis.
The classic text on MAUP is the 1983 paper Openshaw, Stan. “The modifiable areal unit problem. CATMOG (Concepts and techniques in modern geography) 38.” Geo Abstracts, Norwich. 1984..
There are two distinct types of MAUP: Scale (i.e. determining the appropriate size of units for aggregation) and zone (i.e. drawing boundaries or grouping).
#### 5.4.1.1 Scale
The scale problem involves results that change based on data that are analyzed at higher or lower levels of aggregation (Changing the number of units). For example, evaluating data at the state level vs. Census tract level.
The scale problem has moved to the forefront of geographical criminology as a result of the recent interest in small-scale geographical units of analysis. It has been suggested that smaller is better since small areas can be directly perceived by individuals and are likely to be more homogenous than larger areas. - Gerell, Manne. “Smallest is better? The spatial distribution of arson and the modifiable areal unit problem.” Journal of quantitative criminology 33.2 (2017): 293-318.
#### 5.4.1.2 Zone
The zonal problem involves keeping the same scale of research (say, at the state level) but changing the actual shape and size of those areas.
The basic issue with the MAUP is that aggregate units of analysis are often arbitrarily produced by whom ever is in charge of creating the aggregate units. A classic example of this problem is known as Gerrymandering. Gerrymandering involves shaping and re-shaping voting districts based on the political affiliations of the resident citizenry.
The inherent problem with the MAUP and with situations such as Gerrymandering is that units of analysis are not based on geographic principles, and instead are based on political and social biases. For researchers and practitioners the MAUP has very important implications for research findings because it is possible that as arbitrarily defined units of analysis change shape findings based on these units will change as well.
When spatial data are derived from counting or averaging data within areal units, the form of those areal units affects the data recorded, and any statistical measures derived from the data. Modifying the areal units therefore changes the data. Two effects are involved: a zoning effect arising from the particular choice of areas at a given scale; and an aggregation effect arising from the extent to which data are aggregated over smaller or larger areas. The modifiable areal unit problem arises in part from edge effect.
### 5.4.2 Why does MAUP matter?
The practical implications of MAUP are immense for almost all decision-making processes involving GIS technology, since with the availability of aggregated maps, policy could easily focus on issues and problems which might look different if the aggregation scheme used were changed .
All studies based on geographical areas are susceptible to MAUP. The implications of the MAUP affect potentially any area level data, whether direct measures or complex model-based estimates. Here are a few examples of situations where the MAUP is expected to make a difference:
• The special case of the ecological fallacy is always present when Census area data are used to formulate and evaluate policies that address problems at individual level, such as deprivation. Also, it is recognised that a potential source of error in the analysis of Census data is ‘the arrangement of continuous space into defined regions for purposes of data reporting’
• The MAUP has an impact on indices derived from areal data, such as measures of segregation, which can change significantly as a result of using different geographical levels of analysis to derive composite measures .
• The choice of boundaries for reporting mortality ratios is not without consequences: when the areas are too small, the values estimated are unstable, while when the areas are too large, the values reported may be over-smoothed, i.e. meaningful variation may be lost .
• Gerell, Manne. “Smallest is better? The spatial distribution of arson and the modifiable areal unit problem.” Journal of quantitative criminology 33.2 (2017): 293-318.
### 5.4.3 What can we do?
Most often you will just have to remain aware of the MAUP and it’s possible effects. There are some techniques, that can help you address these issues, and the chapter pointed out at the beginning of this section is a great place to start to explore these. It is possible to use also an alternative, zone-free approach to mapping these crime patterns, perhaps by using kernel density estimation. Here we model the relative density of the points as a density surface - essentially a function of location (x,y) representing the relative likelihood of occurrence of an event at that point. We have covered KDE elsewhere in this course.
For the purposes of this course, it’s enough that you know of, and understand the MAUP and its implications. Always be smart when choosing your appropriate spatial unit of analysis, and when you use binning of any form, make sure you consider how and if your conclusions might change compared to another possible approach.
### 5.4.4 Activity 7: Considering MAUP
This is a theoretical activity, think about your answers carefully, discuss if you are in a chatty room, and any questions, do ask! Look at the question for homework 5.1 about the three maps of binning and the hotspot map. Answer this question again, but now in light of what you have learned about MAUP.
## 5.5 Transforming polygons
When you have meaningful spatial units of analysis in your polygons, for example you are interested specifically in Local Autorities, it might make sense to stick with what we did last week, and aggregate the points into these polygons to cheare thematic maps. However, while thematic maps are an accessible and visually appealing method for displaying spatial information, they can also be highly misleading. Irregularly shaped polygons and large differences in the size of areas being mapped can introduce misrepresentation. The message researchers want to get across might be lost, or even worse, misdirect the viewers to erroneous conclusions. This article provides a helpful discussion of the problem illustrating the case with UK election maps. It is worth reading.
Fortunately, there are many methods in R to enhance the legibility of geographic information and the interpretability of what it is trying to be communicated.
• cartogram
• hexmap
• grid
Selecting the appropriate method might depend on the research question being posed (e.g. clustering) and the data itself. Even once a method has been selected, there are different ways of operationalising them.
Let’s explore this using the example of the results of the 2016 EU referendum at Local Authority level, where remain areas clustered in London. A simple thematic map does not necessarily communicate this well because Local Authorities are both small and densely populated in London.
You can download the full set of EU referendum result data as a csv from the Electoral Commission webside. Let’s read it straight into R:
eu_ref <- read_csv("https://www.electoralcommission.org.uk/sites/default/files/2019-07/EU-referendum-result-data.csv")
##
## ── Column specification ────────────────────────────────────────────────────────
## cols(
## .default = col_double(),
## Region_Code = col_character(),
## Region = col_character(),
## Area_Code = col_character(),
## Area = col_character()
## )
## ℹ Use spec() for the full column specifications.
OKAY, now we need a shapefile to join it to. Remember when we got the Manchester lsoa shapefile with the boundary selector? Let’s go back, and this time get Local Authority Districts for England.
In this case that means select “English Districts, UAs and London Boroughs, 2011”:
Once you have the file, download, extract (unzip) and put the folder in your working directory. Mine is in a subfolder in my working directory called data, so I point R inside that folder to find my shape file.
las <- st_read("data/England_lad_2011_gen/england_lad_2011_gen.shp")
## Reading layer england_lad_2011_gen' from data source /Users/reka/Desktop/crime_mapping_textbook/data/England_lad_2011_gen/england_lad_2011_gen.shp' using driver ESRI Shapefile'
## Simple feature collection with 326 features and 4 fields
## Geometry type: MULTIPOLYGON
## Dimension: XY
## Bounding box: xmin: 82644.8 ymin: 5349.399 xmax: 655976.9 ymax: 657599.5
## Projected CRS: OSGB 1936 / British National Grid
We can now join the EU referendum data, as we have learned in the past weeks:
eu_sf <- left_join(las, eu_ref, by = c("name" = "Area"))
Now we can have a look at these data:
ggplot() +
geom_sf(data = eu_sf, aes(fill = Pct_Leave))
We can see that in smaller LAs we don’t even really see the result, as the boundary lines pretty much cover everything. Hmm. Now what we can do is transform the shapes.
#### 5.5.0.1 Activity 8: Cartograms
The last thing we will do today is make some cartograms! Cartogram types of maps distort reality to convey information. They resize and exaggerate any variable on an attribute value.
There are different types of cartograms.
Density-equalizing (contiguous) cartograms are your traditional cartograms. In density-equalizing cartograms, map features bulge out a specific variable. Even though it distorts each feature, it remains connected during its creation. On the other hand, you can have Non-Contiguous Cartograms, where features in non-contiguous cartograms don’t have to stay connected. Finally, Dorling Cartogram (named after professor Danny Dorling) uses shapes like circles and rectangles to depict area. These types of cartograms make it easy to recognize patterns. For example, here is a Dorling Cartogram I made of FixMyStreet reports in London:
Now we can make our own as well, using the cartogram package.
library(cartogram)
Within that there is the cartogram() function, which takes 2 arguments, 1 - the shape file (it can be a SpatialPolygonDataFrame or an sf object), and 2 - the variable which it should use to distort the polygon by.
In our data set we have a variable “electorate” which refers to the total number of registered electors
# construct a cartogram using the percentage voting leave
eu_cartogram <- cartogram(eu_sf, "Electorate")
Again this is some labour intensive work, much like the grid making, you have some time to chill now. Maybe read up on the maths behind this tranformation as well, in the paper Dougenik, J. A., Chrisman, N. R., & Niemeyer, D. R. (1985). An Algorithm To Construct Continuous Area Cartograms. In The Professional Geographer, 37(1), 75-81..
I do have a tip for you if you want to make sure the process does not take too long. You can set a parameter in the cartogram function which is the “itermax” parameter. This specifies the maximum number of iterations we are happy with. If you don’t specify it’s set to 15. Let’s set to 5 for the sake of speed:
# construct a cartogram using the percentage voting leave
eu_cartogram <- cartogram_cont(eu_sf, "Electorate", itermax = 5)
## Mean size error for iteration 1: 4.11884641547245
## Mean size error for iteration 2: 21.1096266805133
## Mean size error for iteration 3: 3.05848955329872
## Mean size error for iteration 4: 2.51480273537651
## Mean size error for iteration 5: 2.92812701653567
And if your cartogram has been created, you can now plot again the referendum results, but using the electorate to change the size of the locad authority:
ggplot() +
geom_sf(data = eu_cartogram, aes(fill = Pct_Leave))
We can now see London much better, and see that darker coloured cluster where much smaller percentage of people voted leave.
Okay that’s probably enough for the day. Nice work crime mappers!
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# How to deal with the quadratic programming in practice when there is no minimal value
Here is a quadratic programming problem: $$\min\limits_{\textbf{x}} f(\textbf{x}) = \textbf{x}\ M \ \textbf{x}^T$$ $$0.04 \leq \sum\limits_{i=1}^n x_i\leq 0.35$$ $$0 \leq x_i\leq 0.08$$ $$1 \leq \sum\limits_{i=1}^n x_iR_i\leq 2$$ where $\textbf{x} = (x_1,\cdots,x_n),$ $M$ the covariance matrix and $\textbf{R} = (R_1,\cdots,R_n)$ return vector are given.
When I deal with this problem in practice, the dimension of covariance matrix $M$ is very large, then it may be not positive defined and there is no minimal value(maybe there are some additional issues). Is there any method in optimization to manage such case, like looking for a approximate positive defined matrix of $M$ with small error?
In theory a covariance matrix is pos def (in practice we can see some issues). Sometimes it helps to use a slightly different formulation where we use the original data explicitly. Using the mean adjusted returns
$$a_{i,t} = r_{i,t}-\mu_i$$
we can form
\begin{align} \min\>&\sum_t w_t^2\\ &w_t = \sum_i a_{i,t} x_i\end{align}
This formulation sometimes behaves better (guaranteed pos def with a nice diagonal $Q$ matrix). (Complete derivation here).
• thx, but the reasons why there is no minimal value in the real practice when $n$ is very large are weakness of code library or theoretically there is no minimal value for the given problem(include M is not semi-positive)? – A.Oreo Apr 22 '17 at 13:22
• The QP is not convex when the Q matrix is not pos def. Most QP solvers only support convex QPs. – Erwin Kalvelagen Apr 22 '17 at 13:39
• but, the sample covariance matrix computed as this way is always semi-positive, I think theoretically it should be a minimal value(?) – A.Oreo Apr 22 '17 at 14:31
• Minimum value has little to do with convexity (even concave problems have a minimum value -- unless unbounded). For numerical reasons a covariance matrix may not be pos def (see the first sentence in my answer). – Erwin Kalvelagen Apr 22 '17 at 14:59
• yeah, but I am also doubt is it possible because of the weakness of the compute programming when the dimension is too large. – A.Oreo Apr 22 '17 at 15:32
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# Norm-wise condition number vs component-wise condition number
I'm going through my lecture notes for a numerical linear algebra class and there were a few things in the chapter which covers condition numbers which I did not quite understand.
Two types of condition numbers are introduced, the first one is given by
$$\kappa_{1}({f(\boldsymbol{x})} ; \boldsymbol{x})=\frac{\|\boldsymbol{J}(\boldsymbol{x})\|}{\|\boldsymbol{f}(\boldsymbol{x})\| /\|\boldsymbol{x}\|}$$
and the second one is
$$\kappa_{2}(f(\boldsymbol{x}) ; \boldsymbol{x}) =\frac{\left|\boldsymbol{J}^{\mathrm{T}}(\boldsymbol{x})\right||\boldsymbol{x}|}{|f(\boldsymbol{x})|}$$ .
My first question is, what is the difference between the two? It says that we can employ the second condition number when the first one provides a "pessimistic" result, but this seems very arbitrary to me.
Then it is derived that the second condition number can be bounded by the first one if the infinity norm is used and the output $$f$$ is assumed to be scalar. For the derivation they used following equation
$$\kappa_{1, \infty}(f ; \boldsymbol{x})=\frac{\left\|\boldsymbol{J}^{\mathrm{T}}(\boldsymbol{x})\right\|_{\infty}\|\boldsymbol{x}\|_{\infty}}{|f(\boldsymbol{x})|}$$.
Because the transpose of the Jacobian matrix was used and $$J^T$$ is a row vector it can be written as $$\left\|\boldsymbol{J}^{\mathrm{T}}(\boldsymbol{x})\right\|_{\infty}=\|\boldsymbol{J}(\boldsymbol{x})\|_{1}=\sum_{i=1}^{m}\left|[\boldsymbol{J}(\boldsymbol{x})]_{i}\right|$$. I did not understand why we use the transpose of $$J$$. Is it possible to do the same with $$x$$ or do we have to take the infinity norm there?
• Would you check with your instructor if there is an infinity norm missing in the definition of $\kappa_2$. Moreover, it is not clear how the fraction is interpreted when $f$ is not a scalar. Aug 25 '20 at 17:39
• Unfortunately my instructor was/is not responding, that's why I asked here in the first place. Aug 27 '20 at 10:52
Your definitions of the two conditions numbers seem to be inconsistent with each other. A slight sticking point is that different authors define the Jacobian differently. Some use (A) $$J_{ij} = \partial f_i / \partial x_j$$ and others use (B) $$J_{ij} = \partial f_j / \partial x_i$$. With the first definition, we have that $$f(x+\Delta x) = f(x) + J(x) \Delta x + O(\|\Delta x\|^2)$$ and with the second we get $$f(x+\Delta x) = f(x) + J^\top(x) \Delta x + O(\|\Delta x\|^2)$$. The first definition appears to use the definition (A) of the Jacobian and the second definition definitely requires one to use definition (B) for the product $$|J^\top(x)||x|$$ to be well-defined. In the case that the norm $$\|\cdot\|$$ is transpose-invariant $$\|A\| = \|A^\top\|$$ it doesn't matter which definition you use. There are enough notational consistencies between different authors that it's hard for me to exactly disambiguate what's happening here. I checked popular numerical linear algebra books (Golub and Van Loan, Trefethen and Bau, Demmel, Higham) and could not find any other explicitly using this particular set of definitions. Perhaps if you could find another source with this set of definitions, I (or someone else) could help further.
Let me now address your main question. Suppose I want to solve the diagonal system of linear equations
$$$$\underbrace{\begin{bmatrix} a & 0 \\ 0 & b \end{bmatrix}}_{=A} \begin{bmatrix} x \\ y \end{bmatrix} = \begin{bmatrix} 1 \\ 1 \end{bmatrix}.$$$$
This corresponds to the function $$f(a,b) = (a^{-1},b^{-1})$$ with Jacobian
$$J(a,b) = -\begin{bmatrix} a^{-2} & 0 \\ 0 & b^{-2} \end{bmatrix}$$
which has norm $$\|J(a,b)\| = \max(a^{-2},b^{-2})$$ in the operator $$\infty$$-norm. Let's assume going forward that $$a > b > 0$$ so $$\|J(a,b)\| = b^{-2}$$. The first condition number is then
$$\kappa_1(f(a,b);(a,b)) = \frac{\|J(a,b)\|}{\|f(a,b)\|/\|(a,b)\|} = \frac{b^{-2}}{b^{-1}/ a} = \frac{a}{b}.$$
Thus if $$a\gg b$$, this problem is very ill-conditioned. Now, let's look at the component-wise condition number
$$\kappa_2(f(a,b);(a,b)) = \frac{\begin{bmatrix} a^{-2} & 0 \\ 0 & b^{-2} \end{bmatrix}\begin{bmatrix}a\\ b\end{bmatrix}}{\begin{bmatrix} a^{-1} \\ b^{-1}\end{bmatrix}} = \begin{bmatrix} 1 \\ 1 \end{bmatrix}.$$
I haven't seen this definition you've given using elementwise division of vectors, and I believe the canonical component-wise condition number would be a norm of this "vector condition number". (e.g. Using the $$\infty$$-norm, $$\kappa_2(f(a,b);(a,b)) = 1$$.) Using the component-wise condition number, the problem seems perfectly well-conditioned! What is going on here?
The standard vanilla norm-wise condition number measures approximately how much we expect the relative error between $$f(x+\Delta x)$$ and $$f(x)$$ to be compared to the relative error between $$x$$ and $$x+\Delta x$$. Specifically,
$$\mbox{relative error in f} \le \kappa \cdot (\mbox{relative error in x}) + \mbox{higher order terms}.$$
If we say $$(a+\Delta a, b+\Delta b)$$ has a relative error, say, $$10^{-6}$$ in the $$\infty$$-norm compared to the true value $$(a,b)$$ this means that the errors $$\Delta a$$ and $$\Delta b$$ in each component are less than $$10^{-6}\|(a,b)\| = 10^{-6}a$$. Note that if $$a$$ is more than $$10^6b$$, then this means the error $$\Delta b$$ can be larger than $$b$$ itself! But when we actually evaluate $$f$$, $$a^{-1}$$ is much much smaller than $$b^{-1}$$ but $$b$$ has been perturbed by a large error $$\Delta b$$ and thus the relative error in $$f$$ (largely dominated by the relative error of $$b^{-1}$$ is very high. In effect, if one considers norm-wise relative error, the relative error of small components of a vector can be made very large and these large component-wise errors can be amplified if $$f$$ depends on the small entries of its input.
In many practical settings, we have an input vector for which every component has small relative error. For example, if the errors $$\Delta a$$ and $$\Delta b$$ are the result of approximating arbitrary real numbers $$a$$ and $$b$$ by floating point numbers, we have that $$|\Delta a| \le \epsilon |a|$$ and $$|\Delta b| \le \epsilon |b|$$ for a small constant $$\epsilon$$. Thus, this worst-case scenario in the last case is impossible, but there's no way to prove that using norms as, if we only assume, $$\|(\Delta a, \Delta b)\| \le \epsilon \|(a,b)\|$$, there's no way to show $$\Delta b$$ is small relative to $$b$$. Component-wise condition numbers do exactly this. They allow you to measure the conditioning of a problem relative to small component-wise perturbations in the input, which allows one much better control over the relative error in small values in the input vector.
At the end of the day, I still have to say the line "we can employ the second condition number when the first one provides a 'pessimistic' result" because there's not a catch-all heuristic to definitively show when componentwise conditioning will or won't give a substantially better error bound. However, I hope that the example I've given is a revealing illustration for how norm-wise conditioning can give misleadingly pessimistic error bounds for a problem and how component-wise conditioning can give more realistic bounds.
• Note that condition numbers are numbers and not vectors. Certainly, we can have a matrix of conditon numbers, but this is not under consideration here. I am quite certain that there was error in the equation for $k_2$. I have include what I perceive to be the correct expression in my reply. It is clear to me what you mean when you speak of the error $\Delta a$, but it can be useful to emphasize that you are really considering $|\Delta a|$. The last line of your last paragraph is not clear to me. It seems to me that a few words were omitted? Aug 24 '20 at 10:21
• @CarlChristian I've made some edits to reflect your comment. I think there is a reasonable definition of a "vector condition number" where $\mbox{norm of relative componentwise error of f} \lesssim (\mbox{vector condition number}) \cdot (\mbox{vector of relative errors in$x$})$ but I'm not positive the OP's definition satisfies this property. Aug 25 '20 at 4:43
The expression for $$\kappa_2$$ does not make sense unless $$f(x)$$ is a scalar. The given expressions for $$\kappa_1$$ and $$\kappa_2$$ are not definitions, but theorems.
In this answer I will rigorously define the normwise relative condition number and the component relative condition number. This should clarify their differences.
Let $$\Omega \subseteq \mathbb{R}^n$$ be an open set, let $$f : \Omega \rightarrow \mathbb{R}^m$$ and let $$x \in \Omega$$. If $$x \not = 0$$ and if $$f(x) \not = 0$$, then the normwise relative condition number $$\kappa_f^{nr}$$ is defined as follows. First we define an auxiliary function $$$$\kappa_f^{nr}(x,\delta) = \sup \left \{ \frac{\|f(x)-f(y)\|}{\|f(x)\|} \big/ \frac{\|x-y\|}{\|x\|}\: : \: 0 < \| x-y\| < \delta \|x\| \right \}.$$$$ where $$\delta > 0$$ is any number such that $$\{ y \in \mathbb{R}^n \: : \: \|x\| < \delta \|x\|) \subseteq \Omega.$$ It is clear that the function $$\delta \rightarrow \kappa_f^{nr}(x,\delta)$$ is nonnegative and nondecreasing. It follows that the limit $$\underset{\delta \rightarrow 0_.}{\lim} \kappa_f^{nr}(x,\delta)$$ exists. This allows us to define the normwise relative condition number $$\kappa_f^{nr}$$ as follows $$\kappa_f^{nr}(x) = \underset{\delta \rightarrow 0_+}{\lim} \kappa_f^{nr}(x,\delta).$$
The normwise relative condition number imposes a hard limit on the normwise relative error which can be achieved. If $$y \in \Omega$$ satisfies $$\|x-y\| \leq \delta \|x\|$$, then $$\frac{\|f(x)-f(y)\|}{\|f(x)\|} = \left(\frac{\|f(x)-f(y)\|}{\|f(x)\|} \big/ \frac{\|x-y\|}{\|x\|}\right) \frac{\|x-y\|}{\|x\|} \leq \kappa_f^{nr}(x,\delta) \frac{\|x-y\|}{\|x\|}$$ Moreover, if $$\delta$$ is sufficiently small, then $$\kappa_f^{nr}(x,\delta) \approx \kappa_f^{nr}(x)$$ is a good approximation. It follows that we cannot expect a normwise relative error which is smaller than $$\frac{\|f(x)-f(y)\|}{\|f(x)\|} \approx \kappa_f^{nr}(x,\delta) \frac{\|x-y\|}{\|x\|}.$$ From this definition it is possible to prove the following result. If $$f : \Omega \rightarrow \mathbb{R}^m$$ is also differentiable at the point $$x \in \Omega$$, then $$\kappa_f^{nr}(x) = \frac{\|Df(x)\|\|x\|}{\|f(x)\|}$$ where $$Df(x) \in \mathbb{R}^{m \times n}$$ is the Jacobian of $$f$$ at the point $$x$$. To be clear, if $$A = Df(x)$$ is the Jacobian of $$f$$ at $$x$$, then $$a_{ij} = \frac{\partial f_i}{\partial x_j}(x)$$.
Now in order to define the componentwise relative condition number, we first define the componentwise relative error. Let $$x \in \mathbb{R}^n$$ denote the target value and let $$y \in \mathbb{R}^n$$ denote the approximation. Then the componentwise relative error is given by $$$$\rho(x,y) = \max \left \{ \frac{|x_j - y_j|}{|x_j|} \: : \: j = 1,2,\dotsc,n \right \},$$$$ where we extend the usual definition of fractions to include $$$$\frac{a}{b} = \begin{cases} 0 & a = 0 \wedge b = 0, \\ \infty & a > 0 \wedge b = 0. \end{cases}$$$$ Now let $$x \in \Omega$$ be a point such that $$x_j \not = 0$$ for all $$j$$ and $$f_i(x) \not = 0$$ for all $$i$$. We begin by defining an auxiliary function $$\kappa_f^{cr}$$ given by $$\kappa_f^{cr}(x,\delta) = \sup \left\{ \frac{\rho(f(x),f(y))}{\rho(x,y)} \: : \: 0 < \rho(x,y) < \delta \right\}.$$ It is clear that $$\delta \rightarrow \kappa_f^{cr}(x,\delta)$$ is a nonnegative and nondecreasing function. It follows that the limit $$\underset{\delta \rightarrow 0_+}{\lim} \kappa_f^{cr}(x,\delta)$$ exists and is nonnegative. This allows us to define the componentwise relative condition number of $$f$$ as follows $$\kappa_f^{cr}(x) = \underset{\delta \rightarrow 0_+}{\lim} \kappa_f^{cr}(x,\delta).$$ The componentwise relative condition number imposes a hard limit on the componentwise accuracy which can be achieved. If $$y \in \Omega$$ is such that $$0 < \rho(x,y) < \delta$$, then $$\rho(f(x),f(y)) = \left(\frac{\rho(f(x),f(y))}{\rho(x,y)}\right) \rho(x,y)\leq \kappa_f^{cr}(x,\delta) \rho(x,y).$$ Moreover, if $$\delta$$ is sufficiently small, then $$\kappa_f^{cr}(x,\delta) \approx \kappa_f{cr}(x)$$ is a good approximation. It follows that we cannot expect a componentwise relative error which is smaller than $$\rho(f(x),f(y)) \approx \kappa_f^{cr}(x,\delta) \rho(x,y).$$ From the definition it is possible to prove the following result. If $$f$$ is also differentiable at $$x \in \Omega$$, then $$\kappa_f^{cr}(x) = \left \|\frac{|Df(x)||x|}{|f(x)|} \right\|_\infty.$$ Here it is vital to appreciate the fact that the division on the right-hand side is componentwise when $$f$$ is a vector function.
It is clear that the two condition numbers measures the sensitivity of $$f$$ to small changes in the input, but they rely on different definitions of "small". If $$f$$ is also scalar function, i.e., if $$m = 1$$, then we have $$\kappa_f^{cr}(x) = \left \|\frac{|Df(x)||x|}{|f(x)|} \right\|_\infty = \frac{\||Df(x)||x|\|_\infty}{|f(x)|} \leq \frac{\||Df(x)|\|_\infty\||x|\|_\infty}{\|f(x)\|_\infty} = \frac{\|Df(x)\|_\infty\|x\|_\infty}{\|f(x)\|_\infty} =\kappa_f^{nr}(x).$$ In this case, we see that the normwise relative condition number is always larger than the componentwise condition number. However, I feel that it is a bit misleading to state that the normwise relative condition number more is pessimistic than the componentwise condition number, simply because they use a different definition of "small".
Much confusion can be avoided by always stating clearly the domain and the codomain of the function in question. In fact, a function is really a triple $$(f,U,V)$$ consisting of a domain $$U$$, a co-domain $$V$$ and a rule $$f$$ for assigning to exact element in the domain $$U$$ exactly one element in the co-domain $$V$$. Unfortunately, the established notation tends to focus only on the rule $$f$$.
The definition of the componentwise relative condition number used here is extracted from the paper "Mixed, componentwise and structured condition numbers" by Gohberg and Koltracht, SIAM J. Matrix Anal. Appl., 14(3), page(s) 688–704, 1993.
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Curator and Contributors
1.00 - Jan Peters
Policy gradient methods are a type of reinforcement learning techniques that rely upon optimizing parametrized policies with respect to the expected return (long-term cumulative reward) by gradient descent. They do not suffer from many of the problems that have been marring traditional reinforcement learning approaches such as the lack of guarantees of a value function, the intractability problem resulting from uncertain state information and the complexity arising from continuous states & actions.
## Introduction
Reinforcement learning is probably the most general framework in which reward-related learning problems of animals, humans or machine can be phrased. However, most of the methods proposed in the reinforcement learning community are not yet applicable to many problems such as robotics, motor control, etc. This inapplicability may result from problems with uncertain state information. Thus, those systems need to be modeled as partially observable Markov decision problems which often results in excessive computational demands. Most traditional reinforcement learning methods have no convergence guarantees and there exist even divergence examples. Continuous states and actions in high dimensional spaces cannot be treated by most off-the-shelf reinforcement learning approaches.
Policy gradient methods differ significantly as they do not suffer from these problems in the same way. For example, uncertainty in the state might degrade the performance of the policy (if no additional state estimator is being used) but the optimization techniques for the policy do not need to be changed. Continuous states and actions can be dealt with in exactly the same way as discrete ones while, in addition, the learning performance is often increased. Convergence at least to a local optimum is guaranteed.
The advantages of policy gradient methods for real world applications are numerous. Among the most important ones are that the policy representations can be chosen so that it is meaningful for the task and can incorporate domain knowledge, that often fewer parameters are needed in the learning process than in value-function based approaches and that there is a variety of different algorithms for policy gradient estimation in the literature which have a rather strong theoretical underpinning. Additionally, policy gradient methods can be used either model-free or model-based as they are a generic formulation.
Of course, policy gradients are not the salvation to all problems but also have significant problems. They are by definition on-policy (note that tricks like importance sampling can slightly alleviate this problem) and need to forget data very fast in order to avoid the introduction of a bias to the gradient estimator. Hence, the use of sampled data is not very efficient. In tabular representations, value function methods are guaranteed to converge to a global maximum while policy gradients only converge to a local maximum and there may be many maxima in discrete problems. Policy gradient methods are often quite demanding to apply, mainly because one has to have considerable knowledge about the system one wants to control to make reasonable policy definitions. Finally, policy gradient methods always have an open parameter, the learning rate, which may decide over the order of magnitude of the speed of convergence, these have led to new approaches inspired by expectation-maximization (see, e.g., Vlassis et al., 2009; Kober & Peters, 2008).
Nevertheless, due to their advantages stated above, policy gradient methods have become particularly interesting for robotics applications as these have both continuous actions and states. For example, there has been a series of successful applications in robot locomotion, where good policy parametrizations such as CPGs are known. Benbrahim & Franklin (1997) already explored 2D dynamic biped walking, Tedrake et al. (2004) extended these results to 3D passive dynamics-based walkers and Endo (2005) showed that a full-body gait with sensory feedback can be learned with policy gradients. Kohl & Stone (2004) were able to apply policy gradients to optimize quadruped gaits. There have also been various applications in skill learning starting with the peg-in-a-hole tasks learned by Gullapalli et al. (1994) and ranging to Peters & Schaals' optimizations of discrete movements primitives such as T-Ball swings.
Note that in most applications, there exist many local maxima; for example, if we were told build a high jumping robot, there is a multitude of styles. Current policy gradient methods would be helpful for improving a jumping style of a teacher, let's say the classical straddle jump. However, discovering a Fosbery flop when starting with a basic straddle jump policy is probably not possible with policy gradient methods.
## Assumptions and Notation
We assume that we can model the control system in a discrete-time manner and we will denote the current time step by $$k\ .$$ In order to take possible stochasticity of the plant into account, we denote it using a probability distribution $$\mathbf{x}_{k+1}\sim p\left( \mathbf{x} _{k+1}\left\vert \mathbf{x}_{k},\mathbf{u}_{k}\right. \right)$$ as model where $$\mathbf{u}_{k}\in\mathbb{R}^{M}$$ denotes the current action, and $$\mathbf{x}_{k}\ ,$$ $$\mathbf{x}_{k+1}\in\mathbb{R}^{N}$$ denote the current and next state, respectively. We furthermore assume that actions are generated by a policy $$\mathbf{u}_{k} \sim\pi_{\mathbf{\theta}}\left( \mathbf{u}_{k}\left\vert \mathbf{x} _{k}\right. \right)$$ which is modeled as a probability distribution in order to incorporate exploratory actions; for some special problems, the optimal solution to a control problem is actually a stochastic controller (Sutton, McAllester, Singh, and Mansour, 2000). The policy is assumed to be parameterized by $$K$$ policy parameters $$\mathbf{\theta} \in\mathbb{R}^{K}\ .$$The sequence of states and actions forms a trajectory denoted by $$\mathbf{\tau}=[\mathbf{x}_{0:H},\mathbf{u}_{0:H}]$$ where $$H$$ denotes the horizon which can be infinite. In this article, we will use the words trajectory, history, trial, or roll-out interchangeably. At each instant of time, the learning system receives a reward denoted by $$r_{k} = r\left( \mathbf{x} _{k},\mathbf{u}_{k}\right) \in\mathbb{R}\ .$$
The general goal of policy optimization in reinforcement learning is to optimize the policy parameters $$\mathbf{\theta}\in\mathbb{R}^{K}$$ so that the expected return
$$J\left( \mathbf{\theta}\right) =E\left\{ \sum\nolimits_{k=0}^{H}a_{k} r_{k}\right\}$$
is optimized where $$a_{k}$$ denote time-step dependent weighting factors, often set to $$a_{k}=\gamma^{k}$$ for discounted reinforcement learning (where $$\gamma$$ is in $$[0,1]$$) or $$a_{k}=1/H$$ for the average reward case.
For real-world applications, we require that any change to the policy parameterization has to be smooth as drastic changes can be hazardous for the actor as well as useful initializations of the policy based on domain knowledge would otherwise vanish after a single update step. For these reasons, policy gradient methods which follow the steepest descent on the expected return are the method of choice. These methods update the policy parameterization according to the gradient update rule
$$\mathbf{\theta}_{h+1}=\mathbf{\theta}_{h}+\alpha_{h}\left. \mathbf{\nabla }_{\mathbf{\theta}}J\right\vert _{\mathbf{\theta}=\mathbf{\theta}_{h}},$$
where $$\alpha_{h}\in\mathbb{R}^{+}$$ denotes a learning rate and $$h\in\{0,1,2,\ldots\}$$ the current update number.
The time step $$k$$ and update number $$h$$ are two different variables. In actor-critic-based policy gradient methods, the frequency of updates of $$h$$ can be nearly as high as of $$k\ .$$ However, in most episodic methods, the policy update $$h$$ will be significantly less frequent. Here, cut-off allows updates before the end of the episode (for $$a_{k}=\gamma^{k}\ ,$$ it is obvious that there comes a point where any future reward becomes irrelevant; a generically good cut-off point). If the gradient estimate is unbiased and learning rates fulfill $$\sum\textstyle_{h=0}^{\infty}\alpha_{h}>0$$ and $$\sum\textstyle_{h=0}^{\infty}\alpha_{h}^{2}=\textrm{const}\ ,$$ the learning process is guaranteed to converge at least to a local minimum.
The main problem in policy gradient methods is to obtain a good estimator of the policy gradient $$\left. \mathbf{\nabla}_{\mathbf{\theta}}J\right\vert _{\mathbf{\theta}=\mathbf{\theta}_{h}}\ .$$ In robotics and control, people have traditionally used deterministic model-based methods for obtaining the gradient (Jacobson & Mayne, 1970; Dyer & McReynolds, 1970; Hasdorff, 1976). However, in order to become autonomous we cannot expect to be able to model every detail of the system. Therefore, we need to estimate the policy gradient simply from data generated during the execution of a task, i.e., without the need for a model. In this section, we will study different approaches and discuss their properties.
## Approaches to Policy Gradient Estimation
The literature on policy gradient methods has yielded a variety of estimation methods over the last years. The most prominent approaches, which have been applied to robotics are finite-difference and likelihood ratio methods, better known as REINFORCE in reinforcement learning.
### Finite-difference Methods
Finite-difference methods are among the oldest policy gradient approaches; they originated from the stochastic simulation community and are quite straightforward to understand. The policy parameterization is varied $$I$$ times by small increments $$\mathbf{\Delta\theta}_{i}, \, i=1\ldots I$$ and for each policy parameter variation $$\mathbf{\theta}_{h}+\mathbf{\Delta\theta}_{i}$$ roll-outs (or trajectories) are performed which generate estimates $$\Delta\hat{J}_{i}\approx J(\mathbf{\theta }_{h}+\mathbf{\Delta\theta}_{i})-J_{\text{ref}}$$ of the expected return. There are different ways of choosing the reference value $$J_{\text{ref}}\ ,$$ e.g. forward-difference estimators with $$J_{\text{ref}}=J(\mathbf{\theta}_{h})$$ and central-difference estimators with $$J_{\text{ref}}=J(\mathbf{\theta}_{h}-\mathbf{\Delta\theta}_{i})\ .$$ The policy gradient estimate $$\mathbf{g}_{\text{FD}}\approx\left. \mathbf{\nabla}_{\mathbf{\theta}}J\right\vert_{\mathbf{\theta} =\mathbf{\theta}_{h}}$$ can be estimated by regression yielding
$$\mathbf{g}_{\text{FD}}=\left( \mathbf{\Delta\Theta}^{T}\mathbf{\Delta\Theta }\right) ^{-1}\mathbf{\Delta\Theta}^{T}\mathbf{\Delta\hat{J}},$$
where $$\mathbf{\Delta\Theta} =[\mathbf{\Delta\theta}_{1},\ldots,\mathbf{\Delta\theta}_{I}]^{T}$$ and $$\mathbf{\Delta\hat{J}}=[\Delta\hat{J}_{1},\ldots ,\Delta\hat{J}_{I}]^{T}$$ denote the $$I$$ samples. This approach can be highly efficient in simulation optimization of deterministic systems (Spall, 2003) or when a common history of random numbers (Glynn, 1987) is being used (the latter is known as PEGASUS in reinforcement learning (Ng & Jordan, 2000)), and the error of the gradient estimate can get close to $$O\left( I^{-1/2}\right)$$ (Glynn, 1987). However, the uncertainty of real systems will result in stochasticity and an artificial common history of random numbers can no longer be applied. Hence, when used on a real system, the performance degrades in a gradient estimate error ranging between $$O\left( I^{-1/4}\right)$$ to $$O\left( I^{-2/5} \right)$$ depending on the chosen reference value (Glynn, 1987). An implementation of this algorithm is shown below.
input: policy parameterization $$\mathbf{\theta}_{h}$$
for $$i=1$$ to $$I$$ do
generate policy variation $$\mathbf{\Delta\theta}_{i}$$
estimate $$\hat{J}_{i}\approx J(\mathbf{\theta}_{h}+\mathbf{\Delta\theta}_{i})=\left\langle \sum\nolimits_{k=0}^{H} a_{k}r_{k}\right\rangle$$ from roll-out
estimate $$\hat{J}_{\text{ref}}\ ,$$ e.g., $$\hat{J}_{\text{ref}}=J(\mathbf{\theta}_{h}-\mathbf{\Delta\theta}_{i})$$ from roll-out
compute $$\Delta\hat{J}_{i}\approx J(\mathbf{\theta}_{h}+\mathbf{\Delta\theta}_{i})-J_{\text{ref}}$$
end for
return gradient estimate $$\mathbf{g}_{\text{FD}} = \left( \mathbf{\Delta\Theta}^{T}\mathbf{\Delta\Theta}\right) ^{-1}\mathbf{\Delta \Theta}^{T}\mathbf{\Delta\hat{J}}$$
Note that an alternative implementation would keep increasing $$I$$ until the gradient estimate converges. The choice of $$I$$ can be essential; empirically it can be observed that taking $$I$$ as twice the number of parameters yields very accurate gradient estimates.
Due to the simplicity of this approach, such methods have been successfully applied to numerous applications. However, the straightforward application is not without peril as the generation of the $$\mathbf{\Delta\theta}_{i}$$ requires proper knowledge of the system, as badly chosen $$\mathbf{\Delta\theta}_{i}$$ can destabilize the policy so that the system becomes instable and the gradient estimation process is prone to fail. If the parameters differ highly in scale, significant difficulties could be the consequences.
Advantages of this approach: Finite-difference methods require very little skill and can usually be implemented out of the box. They work both with stochastic and deterministic policies without any change. It is highly efficient in simulation with a set of common histories of random numbers and on totally deterministic systems.
Disadvantages of this approach: The perturbation of the parameters is a very difficult problem often with disastrous impact on the learning process when the system goes unstable. In the presence of noise on a real system, the gradient estimate error decreases much slower than for the following methods. Performance depends highly on the chosen policy parametrization.
Sehnke et al. (2010) show several interesting newer methods developed in this domain.
### Likelihood Ratio Methods and REINFORCE
Likelihood ratio methods are driven by a different important insight. Assume that trajectories $$\mathbf{\tau}$$ are generated from a system by roll-outs, i.e., $$\mathbf{\tau}\sim p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) =p\left( \left. \mathbf{\tau}\right\vert \mathbf{\theta}\right)$$ with return $$r(\mathbf{\tau})=\sum\textstyle_{k=0}^{H}a_{k}r_{k}$$ which leads to $$J(\theta) = E\left\{ r(\tau) \right\} = \int_{\mathbb{T}} p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) r(\mathbf{\tau})d\mathbf{\tau} \ .$$ In this case, the policy gradient can be estimated using the likelihood ratio (see e.g. Glynn, 1987; Aleksandrov, Sysoyev, and Shemeneva, 1968) better known as REINFORCE (Williams, 1992) trick, i.e., by using
$$\mathbf{\nabla}_{\mathbf{\theta}}p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) = p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) \mathbf{\nabla }_{\mathbf{\theta}}\log p_{\mathbf{\theta}}\left( \mathbf{\tau}\right)$$
from standard differential calculus ($$\mathbf{\nabla }_{\mathbf{\theta}}\log p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) =\mathbf{\nabla}_{\mathbf{\theta}}p_{\mathbf{\theta}}\left( \mathbf{\tau}\right)/p_{\mathbf{\theta}}\left( \mathbf{\tau}\right)$$), we obtain
$$\mathbf{\nabla}_{\mathbf{\theta}}J\left( \mathbf{\theta}\right) = \int_{\mathbb{T}}\mathbf{\nabla}_{\mathbf{\theta}}p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) r(\mathbf{\tau})d\mathbf{\tau} = \int_{\mathbb{T}} p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) \mathbf{\nabla }_{\mathbf{\theta}}\log p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) r(\mathbf{\tau})d\mathbf{\tau} = E\left\{ \mathbf{\nabla }_{\mathbf{\theta}}\log p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) r(\mathbf{\tau})\right\}.$$
As the expectation $$E\{\cdot\}$$ can be replaced by sample averages, denoted by $$\langle\cdot\rangle\ ,$$ only the derivative $$\mathbf{\nabla}_{\mathbf{\theta}}\log p_{\mathbf{\theta}}\left( \mathbf{\tau}\right)$$ is needed for the estimator. Importantly, this derivative can be computed without knowledge of the generating distribution $$p_{\mathbf{\theta}}\left( \mathbf{\tau}\right)$$ as
$$p_{\mathbf{\theta}}\left( \mathbf{\tau}\right)=p(\mathbf{x}_{0})\prod\nolimits_{k=0} ^{H}p\left( \mathbf{x}_{k+1}\left\vert \mathbf{x}_{k},\mathbf{u}_{k}\right. \right) \pi_{\mathbf{\theta}}\left( \mathbf{u}_{k}\left\vert \mathbf{x} _{k}\right. \right)$$
implies that
$$\mathbf{\nabla}_{\mathbf{\theta}}\log p_{\mathbf{\theta}}\left( \mathbf{\tau }\right) =\sum\nolimits_{k=0}^{H}\mathbf{\nabla}_{\mathbf{\theta}}\log \pi_{\mathbf{\theta}}\left( \mathbf{u}_{k}\left\vert \mathbf{x}_{k}\right. \right)$$
as only the policy depends on $$\mathbf{\theta}\ .$$
Thus, the derivatives of $$p\left( \mathbf{x}_{k+1}\left\vert \mathbf{x}_{k},\mathbf{u}_{k}\right. \right)$$ do not have to be computed and no model needs to be maintained. However, if we had a deterministic policy $$\mathbf{u}=\pi(\mathbf{x})$$ instead of a stochastic policy $$\mathbf{u}\sim\pi(\mathbf{u}|\mathbf{x})\ ,$$ computing such a derivative would require the derivative $$\mathbf{\nabla}_{\mathbf{\theta}}\log p\left( \mathbf{x}_{k+1}\left\vert \mathbf{x}_{k},\mathbf{u}_{k}\right. \right) = \mathbf{\nabla}_{\mathbf{u}_k}\log p\left( \mathbf{x}_{k+1}\left\vert \mathbf{x}_{k},\mathbf{u}_{k}\right.\right) \mathbf{\nabla}_{\mathbf{\theta}} \pi_{\mathbf{\theta}}\left(\mathbf{x}_{k}\right)$$ to compute $$\mathbf{\nabla}_{\mathbf{\theta}}\log p_{\mathbf{\theta}}\left( \mathbf{\tau}\right)$$ and, hence, it would require a system model.
In order to reduce the variance of the gradient estimator, a constant baseline can be subtracted from the gradient, i.e.,
$$\mathbf{\nabla}_{\mathbf{\theta}}J\left( \mathbf{\theta}\right) =E\left\{ \mathbf{\nabla}_{\mathbf{\theta}}\log p_{\mathbf{\theta}}\left( \mathbf{\tau }\right) \left( r(\mathbf{\tau})-b\right) \right\} ,$$
where the baseline $$b\in\mathbb{R}$$ can be chosen arbitrarily (Williams, 1992). It is straightforward to show that this baseline does not introduce bias in the gradient as differentiating $$\int_{\mathbb{T}} p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) d\mathbf{\tau}=1$$ implies that
$$\int_{\mathbb{T}}\mathbf{\nabla}_{\mathbf{\theta} }p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) d\mathbf{\tau}=0 \ ,$$
and, hence, the constant baseline will vanish for infinite data while reducing the variance of the gradient estimator for finite data. See Peters & Schaal, 2008 for an overview of how to choose the baseline optimally. Therefore, the general path likelihood ratio estimator or episodic REINFORCE gradient estimator is given by
$$\mathbf{g}_{\text{RF}}=\left\langle \left( \sum\nolimits_{k=0}^{H} \mathbf{\nabla}_{\mathbf{\theta}}\log\pi_{\mathbf{\theta}}\left( \mathbf{u}_{k}\left\vert \mathbf{x}_{k}\right. \right) \right) \left( \sum\nolimits_{l=0}^{H}a_{l}r_{l}-b\right) \right\rangle,$$
where $$\left\langle \cdot\right\rangle$$ denotes the average over trajectories. This type of method is guaranteed to converge to the true gradient at the fastest theoretically possible error decrease of $$O\left( I^{-1/2}\right)$$ where $$I$$ denotes the number of roll-outs (Glynn, 1987) even if the data is generated from a highly stochastic system. An implementation of this algorithm will be shown below together with the estimator for the optimal baseline.
input: policy parameterization $$\mathbf{\theta}_{h}$$
repeat
perform a trial and obtain $$\mathbf{x}_{0:H},\mathbf{u}_{0:H},r_{0:H}$$
for each gradient element $$g_{k}$$
estimate optimal baseline
$$b=\frac{\left\langle \left( \sum\nolimits_{h=0}^{H} \mathbf{\nabla}_{\theta_{k}}\log\pi_{\mathbf{\theta}}\left( \mathbf{u}_{h}\left\vert \mathbf{x}_{h}\right. \right) \right) ^{2}\sum\nolimits_{l=0}^{H}a_{l}r_{l}\right\rangle }{\left\langle \left( \sum\nolimits_{h=0}^{H}\mathbf{\nabla}_{\theta_{k}}\log\pi_{\mathbf{\theta} }\left( \mathbf{u}_{h}\left\vert \mathbf{x}_{h}\right. \right) \right) ^{2}\right\rangle }$$
$$g_{k}=\left\langle \left( \sum\nolimits_{h=0}^{H}\mathbf{\nabla }_{\theta_{k}}\log\pi_{\mathbf{\theta}}\left( \mathbf{u}_{h}\left\vert \mathbf{x}_{h}\right. \right) \right) \left( \sum\nolimits_{l=0}^{H} a_{l}r_{l}-b\right) \right\rangle$$
end for
until gradient estimate $$\mathbf{g}_{\text{RF}}=[g_{1},\ldots,g_{K}]$$ converged
return gradient estimate $$\mathbf{g}_{\text{RF}}=[g_{1},\ldots,g_{K}]$$
Advantages of this approach: Besides the theoretically faster convergence rate, likelihood ratio gradient methods have a variety of advantages in comparison to finite difference methods when applied to robotics. As the generation of policy parameter variations is no longer needed, the complicated control of these variables can no longer endanger the gradient estimation process. Furthermore, in practice, already a single roll-out can suffice for an unbiased gradient estimate viable for a good policy update step, thus reducing the amount of roll-outs needed. Finally, this approach has yielded the most real-world robotics results (Peters & Schaal, 2008) and the likelihood ratio gradient is guaranteed to achieve the fastest convergence of the error for a stochastic system.
Disadvantages of this approach: When used with a deterministic policy, likelihood ratio gradients have to maintain a system model. Such a model can be very hard to obtain for continuous states and actions, hence, the simpler finite difference gradients are often superior in this scenario. Similarly, finite difference gradients can still be more useful than likelihood ratio gradients if the system is deterministic and very repetitive. Also, the practical implementation of a likelihood ratio gradient method is much more demanding than the one of a finite difference method.
One of the main reasons for using policy gradient methods is that we intend to do just a small change $$\mathbf{\Delta\theta}$$ to the policy $$\pi_{\mathbf{\theta}}$$ while improving the policy. However, the meaning of small is ambiguous. When using the Euclidian metric of $$\sqrt{\mathbf{\Delta \theta}^{T}\mathbf{\Delta\theta}}\ ,$$ then the gradient is different for every parameterization $$\mathbf{\theta}$$ of the policy $$\pi_{\mathbf{\theta}}$$ even if these parameterization are related to each other by a linear transformation (Kakade, 2002). This problem poses the question of how we can measure the closeness between the current policy and the updated policy based upon the distribution of the paths generated by each of these. In statistics, a variety of distance measures for the closeness of two distributions (e.g., $$p_{\mathbf{\theta}}\left( \mathbf{\tau}\right)$$ and $$p_{\mathbf{\theta}+\mathbf{\Delta\theta}}\left( \mathbf{\tau}\right)$$) have been suggested, e.g., the Kullback-Leibler divergence $$d_{\text{KL}}\left( p_{\mathbf{\theta}},p_{\mathbf{\theta}+\mathbf{\Delta\theta}}\right)\ ,$$ the Hellinger distance $$d_{\text{HD}}$$ and others (Su & Gibbs, 2002). Many of these distances (e.g., the previously mentioned ones) can be approximated by its second order Taylor expansion, i.e., by
$$d_{\text{KL}}\left( p_{\mathbf{\theta}},p_{\mathbf{\theta}+\mathbf{\Delta \theta}}\right) \approx\mathbf{\Delta\theta}^{T}\mathbf{F}_{\mathbf{\theta} }\text{ }\mathbf{\Delta\theta},$$
where
$$\mathbf{F}_{\mathbf{\theta}}=\int_{\mathbb{T}}p_{\mathbf{\theta} }\left( \mathbf{\tau}\right) \nabla\log p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) \nabla\log p_{\mathbf{\theta}}\left( \mathbf{\tau }\right) ^{T}d\mathbf{\tau}=\left\langle \nabla\log p_{\mathbf{\theta} }\left( \mathbf{\tau}\right) \nabla\log p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) ^{T}\right\rangle$$
is known as the Fisher-information matrix. Let us now assume that we restrict the change of our policy to $$d_{\text{KL}}\left( p_{\mathbf{\theta}},p_{\mathbf{\theta}+\mathbf{\Delta \theta}}\right) \approx\mathbf{\Delta\theta}^{T}\mathbf{F}_{\mathbf{\theta} }\text{ }\mathbf{\Delta\theta} = \varepsilon,$$ where $$\varepsilon$$ needs to be a very small number (i.e., close to zero).
In that case, the natural gradient is defined by Amari (1998) as the update $$\mathbf{\Delta\tilde{\theta}}$$ that is most similar to the true gradient $$\mathbf{\nabla}_{\mathbf{\theta}}J$$ while the change in our path distribution is limited to $$\varepsilon\ .$$ Hence, it is given by the program
$$\operatorname{argmax}_{\mathbf{\Delta{\theta}}}\mathbf{\Delta{\theta}}^{T}\mathbf{\nabla }_{\mathbf{\theta}}J \quad \mathbf{s.t.} \quad \mathbf{\Delta{\theta}}^{T}\mathbf{F} _{\mathbf{\theta}}\text{ }\mathbf{\Delta{\theta}} = \varepsilon.$$
The solution to this program is given by
$$\mathbf{\Delta\theta} \propto \mathbf{F}_{\mathbf{\theta}}^{-1}\mathbf{\nabla}_{\mathbf{\theta}}J,$$
where $$\mathbf{\nabla}_{\mathbf{\theta}}J$$ denotes the regular likelihood ratio policy gradient from the previous section. The update step is unique up to a scaling factor, which is often subsumed into the learning rate. It can be interpreted as follows: determine the maximal improvement $$\mathbf{\Delta{\theta}}$$ of the policy for a constant fixed change of the policy $$\mathbf{\Delta{\theta}}^{T}\mathbf{F}_{\mathbf{\theta}}\mathbf{\Delta{\theta}}\ .$$
As illustrated in Figure 1, the natural gradient update in Figure 1 (b) corresponds to a slightly rotated regular policy gradient update in Figure 1 (a). It can be guaranteed that it is always turned by less than 90 degrees (Amari, 1998), hence all convergence properties of the regular policy gradient transfer.
Figure 1: When plotting the expected return landscape for a simple problem such as an 1d linear quadratic regulation, the differences between regular (‘vanilla’) and natural policy gradients becomes apparent.
This type of approach has its origin in supervised learning (Amari, 1998). It was first suggested in the context of reinforcement learning by Kakade (2002) and has been explored in greater depth in (Bagnell & Schneider, 2003; Peters, Vijayakumar & Schaal, 2003, 2005; Peters & Schaal, 2008). The strongest theoretical advantage of this approach is that its performance no longer depends on the parameterization of the policy and is therefore safe to be used for arbitrary policies. Hence, the regular policy gradient is sometimes referred to as a flavored or vanilla gradient, as it keeps the vanilla flavor' of the policy. However, a well-chosen policy parametrization can sometimes results in better convergence of the policy gradient than the natural policy gradient. Nevertheless, in practice, a learning process based on natural policy gradients often converges significantly faster for most practical cases. Figure 1 gives an impression of the differences in the learning process: while the regular policy gradient often points to plateaus with little exploration, the natural gradient points to the optimal solution.
One of the fastest general algorithms for estimating natural policy gradients which does not need complex parameterized baselines is the episodic natural actor critic. This algorithm, originally derived in (Peters, Vijayakumar & Schaal, 2003), can be considered the natural' version of REINFORCE with a baseline optimal for this gradient estimator. However, for steepest descent with respect to a metric, the baseline also needs to minimize the variance with respect to the same metric. In this case, we can minimize the whole covariance matrix of the natural gradient estimate $$\mathbf{\Delta\hat{\theta}}$$ given by
$$\mathbf{\Sigma} =\operatorname{Cov}\left\{ \mathbf{\Delta\hat{\theta} }\right\} _{\mathbf{F}_{\mathbf{\theta}}}=E\left\{ \left( \mathbf{\Delta\hat{\theta}-F}_{\mathbf{\theta}} ^{-1}\mathbf{g}_{\text{RF}}\left( b\right) \right) ^{T}\mathbf{F} _{\mathbf{\theta}}\left( \mathbf{\Delta\hat{\theta}-F}_{\mathbf{\theta}} ^{-1}\mathbf{g}_{\text{RF}}\left( b\right) \right) \right\} ,$$
with
$$\mathbf{g}_{\text{RF}}\left( b\right) =\left\langle \nabla\log p_{\mathbf{\theta}}\left( \mathbf{\tau}\right) \left( r\left( \mathbf{\tau}\right) -b\right) \right\rangle$$
being the REINFORCE gradient with baseline $$b\ .$$ The re-weighting with the Fisher information ensures that the best identifiable gradient components get the highest weight. As outlined in (Peters & Schaal, 2008), it can be shown that the minimum-variance unbiased natural gradient estimator can be determined as shown below.
input: policy parameterization $$\mathbf{\theta}_{h}$$
repeat
perform $$M$$ trials and obtain $$\mathbf{x}_{0:H},\mathbf{u}_{0:H},r_{0:H}$$ for each trial
Obtain the sufficient statistics
Policy derivatives $$\mathbf{\psi}_{k}=\mathbf{\nabla}_{\theta}\log\pi_{\mathbf{\theta}}\left( \mathbf{u}_{k}\left\vert \mathbf{x}_{k}\right. \right)$$
Fisher matrix $$\mathbf{F}_{\mathbf{\theta}}=\left\langle \left( \sum\nolimits_{k=0}^{H}\mathbf{\psi}_{k}\right)\left( \sum\nolimits_{l=0}^{H}\mathbf{\psi}_{l}\right) ^{T}\right\rangle$$
Vanilla gradient $$\mathbf{g}=\left\langle\left(\sum\nolimits_{k=0}^{H}\mathbf{\psi}_{k}\right) \left(\sum\nolimits_{l=0}^{H}a_{l}r_{l}\right) \right\rangle$$
Eligibility $$\mathbf{\phi}=\left\langle \left(\sum\nolimits_{k=0}^{H}\mathbf{\psi}_{k}\right) \right\rangle$$
Average reward $$\bar{r}=\left\langle\sum\nolimits_{l=0}^{H}a_{l}r_{l}\right\rangle$$
Baseline $$b=\mathbf{Q}\left( \bar {r}-\mathbf{\phi}^{T}\mathbf{F}_{\mathbf{\theta}}^{-1}\mathbf{g}\right)$$
with $$\mathbf{Q}=M^{-1}\left( 1+\mathbf{\phi}^{T}\left( M\mathbf{F}_{\mathbf{\theta}}-\mathbf{\phi\phi}^{T}\right)^{-1}\mathbf{\phi}\right)$$
Natural gradient $$\mathbf{g}_{\text{NG}}=\mathbf{F}_{\mathbf{\theta}}^{-1}\left( \mathbf{g}-\mathbf{\phi}b\right)$$
until gradient estimate $$\mathbf{g}_{\text{NG}}=[g_{1},\ldots,g_{h}]$$ converged
return gradient estimate $$\mathbf{g}_{\text{NG}}=[g_{1},\ldots,g_{h}]$$
For the derivation, see (Peters & Schaal, 2008).
Advantages of this approach: Natural policy gradients differ in a deciding aspect from both finite difference gradients and regular likelihood ratio gradients, i.e., they are independent from the choice of policy parametrization if the choices have the same representational power. As a result, they can be an order of magnitude faster than the regular gradient. They also profit from most other advantages of the regular policy gradients.
Disadvantages of this approach: In comparison to the regular policy gradient, there are three disadvantages: first, the matrix inversion in the gradient estimators may be numerically brittle and may scale worse (note that there are tricks to alleviate this problem). Second, if we can find a special policy parametrization that trivializes a problem, the natural policy gradient may not make use of it. Third, the natural policy gradient estimators are often much harder to implement.
## Conclusion
We have presented an quick overview on policy gradient methods. While many details needed to be omitted and may be found in (Peters & Schaal, 2008), this entry roughly represents the state of the art in policy gradient methods. All three major ways of estimating first order gradients, i.e., finite-difference gradients, vanilla policy gradients and natural policy gradients are discussed in this article and practical algorithms are given.
## References
• V. Aleksandrov, V. Sysoyev, and V. Shemeneva, Stochastic optimization, Engineering Cybernetics, vol. 5, pp. 11-16, 1968.
• S. Amari, Natural gradient works efficiently in learning, Neural Computation, vol. 10, 1998.
• J. Bagnell and J. Schneider, Covariant policy search, International Joint article on Artificial Intelligence, 2003.
• J. Baxter and P. Bartlett, Direct gradient-based reinforcement learning, Journal of Artificial Intelligence Research, 1999.
• H. Benbrahim and J. Franklin, Biped dynamic walking using reinforcement learning, Robotics and Autonomous Systems, vol. 22, pp. 283–302, 1997.
• A. Berny, Statistical machine learning and combinatorial optimization, In L. Kallel, B. Naudts, and A. Rogers, editors, Theoretical Aspects of Evolutionary Computing, Lecture Notes in Natural Computing, 2000.
• P. Dyer and S. R. McReynolds, The Computation and Theory of Optimal Control. New York: Academic Press, 1970.
• G. Endo, J. Morimoto, T. Matsubara, J. Nakanishi, and G. Cheng, Learning CPG sensory feedback with policy gradient for biped locomotion for a full-body humanoid, in AAAI 2005, 2005.
• R. Fletcher and R. Fletcher, Practical Methods of Optimization. John Wiley & Sons, 2000.
• P. Glynn, Likelihood ratio gradient estimation for stochastic systems, Communications of the ACM, vol. 33, no. 10, pp. 75-84, October 1990.
• P. Glynn, Likelihood ratio gradient estimation: an overview, in Proceedings of the 1987 Winter Simulation Conference, Atlanta, GA, 1987, pp. 366--375.
• E. Greensmith, P. Bartlett, and J. Baxter, Variance reduction techniques for gradient estimates in reinforcement learning, Advances in Neural Information Processing Systems, 2001.
• V. Gullapalli, Associative reinforcement learning of real-value functions, SMC, 1991.
• V. Gullapalli, J. Franklin, and H. Benbrahim, Acquiring robot skills via reinforcement learning, IEEE Control Systems, vol. 14, no. 39, 1994.
• L. Hasdorff, Gradient optimization and nonlinear control. John Wiley & Sons, 1976.
• D. H. Jacobson and D. Q. Mayne, Differential Dynamic Programming. New York: American Elsevier Publishing Company, Inc., 1970.
• J. Kober and J. Peters, Policy Search for Motor Primitives in Robotics, Advances in Neural Information Processing Systems 22 (NIPS), Cambridge, MA: MIT Press, 2008.
• N. Kohl and P. Stone, Policy gradient reinforcement learning for fast quadrupedal locomotion, in Proceedings of the IEEE International Conference on Robotics and Automation, New Orleans, LA, May 2004.
• G. Lawrence, N. Cowan, and S. Russell, Efficient gradient estimation for motor control learning, in Proc. UAI-03, Acapulco, Mexico, 2003.
• A. Y. Ng and M. Jordan, PEGASUS: A policy search method for large MPDs and POMDPs, in Proceedings of the Sixteenth Conference on Uncertainty in Artificial Intelligence, 2000.
• J. Peters and S. Schaal, (2008). "Natural actor critic," Neurocomputing, 71, 7-9, pp.1180-1190.
• J. Peters and S. Schaal, (2008). "Reinforcement learning of motor skills with policy gradients," Neural Networks, 21, 4, pp.682-97.
• J. Peters, S. Vijayakumar, and S. Schaal, Reinforcement learning for humanoid robotics, in IEEE/RSJ International Conference on Humanoid Robotics, 2003.
• J. Peters, S. Vijayakumar, and S. Schaal, Natural actor-critic, in Proceedings of the European Machine Learning Conference (ECML)}, 2005.
• F. Sehnke, C. Osendorfer, T. Rückstiess, A. Graves, J. Peters, J. Schmidhuber. Parameter-exploring policy gradients. Neural Networks 23(2), 2010.
• J. C. Spall, Introduction to Stochastic Search and Optimization: Estimation, Simulation, and Control. Hoboken, NJ: Wiley, 2003.
• F. Su and A. Gibbs, On choosing and bounding probability metrics, International Statistical Review, vol. 70, no. 3, pp. 419-435, 2002.
• R. Sutton, D. McAllester, S. Singh, and Y. Mansour, Policy gradient methods for reinforcement learning with function approximation, Advances in Neural Information Processing Systems, 2000.
• R. Tedrake, T. W. Zhang, and H. S. Seung. Stochastic policy gradient reinforcement learning on a simple 3D biped. In Proceedings of the IEEE International Conference on Intelligent Robots and Systems (IROS), vol. 3, pages 2849-2854, Sendai, Japan, September 2004.
• R. J. Williams, Simple statistical gradient-following algorithms for connectionist reinforcement learning, Machine Learning, vol. 8, no. 23, 1992.
• N. Vlassis, M. Toussaint, G. Kontes, and S. Piperidis. Learning Model-free Robot Control by a Monte Carlo EM Algorithm. Autonomous Robots, 27(2):123-130, 2009.
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# Homework Help: Electric Field question
1. Jan 6, 2005
### thursdaytbs
Electric Field question:
Two charges are located on the x axis: q1 = +6.0 micro-Coloumbs at x1=+4cm, and q2=+6 micro-coloumbs at x2 = -4cm. Two other charges are located on the y-axis: q3 = +3 micro-Coloumbs at y3=+5cm, and q4 = -8 micro coloumbs at y4 = +7cm. Find the net electric field (magnitude and direction) at the origin.
What I've tried to do is say E = F/q, and F = Kq1q2 / r^2, therefore E = (kq1q2 / r^2) / q. since q2 = origin, it = 1? and the q1 and q cancel out? So it becomes: E=k/r^2?
I'm pretty sure i'm doing it wrong and was wondering if someone could just point me in the right direction?
Any help appreciaited, thanks.
2. Jan 6, 2005
### dextercioby
HINT:The electric (electrostatic) field created by a charge 'q' at the point $\vec{r}$ is given by
$$\vec{E}_{q,\vec{r}}=:\frac{q}{4\pi\epsilon_{0}r^{2}}\frac{\vec{r}}{r}$$
,where $\vec{r}$ is the position vector at the point u wish to calculate the fiels wrt to the point in which is the source "q".
Daniel.
PS.You'll have to apply that formula 4 times (for each charge) and then add those 4 vectors obtained.
Last edited: Jan 6, 2005
3. Jan 6, 2005
### apchemstudent
E = F/q(o) where q(o) is the charge experiencing the force.
so E = Kq1q(o)/(r^2*q(o)) <----q1 is the charge providing the force and the q(o) is the charge that would be at the origin. However though, as you mentioned before, it does cancel out.
4. Jan 6, 2005
### thursdaytbs
Thanks for the help everyone.
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# ordinal regression or Spearman correlation?
I am conducting research investigating two different groups of women: one group of Short-Stature Women (SSW) and another with Non-Short Women (NSW). We have the hypothesis that SSW has an inaccurate auto-perception of their current body size (CBS). We assessed CBS with a figure rating scale, consisting of 9 different silhouettes, ranging from 1 to 9 (which would assess something like from "malnourished" to "very obese"). We know that CBS is highly determined by the person's Body Mass Index (BMI). Hence, we would like to know if the BMI is a significantly better "predictor" of CBS in NSW compared to SSW.
My first approach was to run two Spearman rho rank correlation test (one for each group (SSW and NSW), between BMI and CBS) and then to compare both coefficients using the Fisher's Z-test. Nevertheless, I am pretty sure that I can treat CBS as an ordinal variable, right? So, it seems to me like an ordinal regression (using CBS as DV and BMI as IV) would be more suitable to my data. If this is true, my problem is that I do not know how to compare coefficients for ordinal regression. Would it be comparing Nagelkerke-R²? How can I do this?
To summarize I have 2 main questions: a) Is Spearman rho rank correlation with comparison of the coefficients by Fisher's Z-test adequate in this case? and b) If ordinal regression is more adequate, how can I compare the coefficients of the regression between my two groups?
Yes, CBS sounds ordinal. If you're only interested in comparing bivariate relationships, comparison of Spearman's $\rho$s seems fair enough to me. However, an ordinal regression model would allow you to estimate the independent relationships of BMI and stature while controlling the effects of each other predictor. You could also test whether these factors moderate each other by including an interaction term. For more on that, see "How to test whether a regression coefficient is moderated by a grouping variable?" and "What is the correct way to test for significant differences between coefficients?"
The method described in the latter question is correct for your purposes in multiple regression (though it wasn't in that OP's case). If you want to calculate the probability that your two predictors' slope coefficients would differ by at least as much as they do in your sample if (1) you were to collect another equivalent sample from the exact same population, and if (2) your predictors are actually equally related to CBS, then you can do this with a z-test: $$Z = \frac{b_1 - b_2}{\sqrt{SE_{b_1}^2 + SE_{b_2}^2}}$$
You can convert the resultant z statistic to a probability using pnorm in or with other methods described here: "How to deal with Z-score greater than 3?"
By the way, if you have continuous height data, you probably ought to reconsider dichotomizing stature into short and non-short. This wastes information that could improve your regression model and correlation estimates; you would probably get smaller standard errors by entering both BMI and height data as originally measured (if you have it) as predictors in multiple ordinal regression of CBS.
• Thanks Nick. First, I do have continuous height data, but the design of the research is to strictly compare SSW (<150cm defined by World Health Organization) and NSW (>160 cm). So I have nobody between 150-160 cm. Hence, my interest is really comparing findings between groups. I was somehow aware that I could include a dummy variable in the model to compare regression coefficients, but only for a linear regression. Actually, my SPSS output for ordinal regression using BMI as IV and CBS as DV does not show something like a "coefficient" of the linear regression, except for the pseudo-R². – NassibBueno Jun 10 '14 at 3:02
• @NassibBueno: that might be an unfortunate consequence of using SPSS ;) you should be able to write the syntax manually to produce slope coefficients for your predictors if necessary; there are such components of the ordinal regression model. Maybe it's time to switch to R? I'm getting slope coefficients out by default using polr from the MASS package... – Nick Stauner Jun 10 '14 at 5:43
• You are right, I began to use SPSS due to it "deceiving" user-friendly interface, and now I feel its lack of extra resources. Nevertheless, I am able to use Stata, and I will find out how to calculate coefficients for the ordinal regression there and then I will apply the methods described by you to compare coefficients. If I fail in last case, I am at least safe to use the Spearman correlation with Fisher Z-test approach, right? Thank you again, Nick. – NassibBueno Jun 11 '14 at 2:05
• Yeah, it's not an unsafe method AFAIK; it's just rather limited. You can do a lot more with ordinal regression than with comparison of bivariate correlations. – Nick Stauner Jun 11 '14 at 2:46
• Nick, I think I did it. I run the ologit command in Stata (and realized that SPSS do show me a coefficient for the ordinal regression, but he calls it "estimate"). The I found both coefficients and SE, for SSW (0.1754 ; 0.06262) and NSW (0.2639, 0.0528). I applied your equation and found a Z-value of -13.4, which means a a really small p-value, right? (I could not calculate the exact p). Hence I conclude that BMI predicts CBS in significantly different ways between SSW and NSW (P < .01), right? the problem is that the CI95% I receive are: SSW [0.0526 to 0.2981] and NSW: [0.1603 to 0.3675]. – NassibBueno Jun 11 '14 at 2:59
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How I can convert genotype data in a variety of pedigree formats R
2
0
Entering edit mode
4.4 years ago
BlackHole • 0
I have a genotype data as a matrix of 10 samples (columns) and 560 000 SNPs (raws). I want to convert this data for further analysis , but have not MAP and PED file (PLINK format) to use GenABEL and I don't know any ways to do this conversion.
Here's a few rows and columns to show you what it looks like:
S1 S2 S3 S4 S5
rs75406208 CC CC CG CG NA
rs200142685 AG AG GG GG GG
rs369829527 NA NA GG GG GG
rs76412254 GG GG GG GG GG
rs80033621 AA AA AA AA AA
rs62608737 GG GG GG GG GG
rs373506129 NA NA CC CC CC
Does anyone know any way to do it?
SNP R • 1.4k views
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Perhaps I missed something, but what's the D?
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D is deletion I is inversion And I have many polymorphisms such as AG, AT, AA , GG, CC, CG, TT
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I is insertion and not inversion that is something else
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of course, i confused
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This is weird. So you have a deletion for snp rs144430729, while that's a C/T SNP. Doesn't make sense to me. How did you obtain this data?
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It is not my data, I got them from my colleagues, to conduct a joint analysis with the metabolome
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If this is sequencing data, try to get the original output. That will make things less painful and less error-prone.
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4.4 years ago
Floris Brenk ▴ 980
Creating the ped file is easy with the information you already have. see for the format here: http://pngu.mgh.harvard.edu/~purcell/plink/data.shtml just transpose what you have now and add a few columns:
Family ID
Individual ID
Paternal ID
Maternal ID
Sex (1=male; 2=female; other=unknown)
Phenotype
For the map file you have to be a bit more creative and get the actual chromosome location etc of the snps probably by extracting it from dbsnp or similar.
CHR RS-number score BP
1 rs123456 0 1234555
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I try to upload my data in dbsnp, but the end result was a blank sheet, and I got message that RS number(s) not found in dbSNP
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# How to understand why massless particles must travel at c?
1. Nov 24, 2012
### SecretSnow
First of all, i need to say that i have read various threads posted by other users in physicsforum who have asked the same question. However, I still don't have a clear picture of why massless particles must travel at c. Personally, I have came up with an explanation which is rather simple, which may or may not be valid, and of course, i wish to validate it here. Another thing I wish to know is why must massless particles travel at c according to the 'equation way'? That is, through this equation $E^2= (mc^2)^2 + (pc)^2$
This is my own guess: All objects with mass can reach c, given that there is time for it to accelerate all the way to c. However, for massless particles they reach c immediately because they do not need time to accelerate and they reach c in no time, or 0 seconds. Hence, we perceive that all massless particles must travel at c, since there is no way in which we can view a massless particle to be travelling at a speed lower than c because it just reaches c instantly. Is this reasoning valid? However, there's another question. Am i right to say that as long an object is allowed to accelerate indefinitely in space in the same direction without any resistance or collision, it will reach the cosmic speed limit?
Of course, I would definitely like to understand this concept through the 'legitimate' way or 'equation way'. These are some links which otaher users have posted about the same question:
2. Nov 24, 2012
### Staff: Mentor
No.
They do not even accelerate.
$E^2= (mc^2)^2 + (pc)^2$
$E=pc \frac{c}{v}$
For massless particles, E=pc and therefore v=c.
3. Nov 24, 2012
### Staff: Mentor
A useful general relationship for the velocity as a fraction of the speed of light is
$$\frac{v}{c} = \frac{pc}{E}$$
For example, an electron with momentum 300 keV/c and energy 400 keV has v/c = 0.75, i.e. v = 0.75c.
For a photon, pc = E.
No. There is never enough time to reach c, even in principle. It would require delivering an infinite amount of energy to the object, which would require an infinite amount of time. You can get it infinitesimally close to c; how close depends on how much energy you have available. But you can never get it all the way to c.
Last edited: Nov 24, 2012
4. Nov 25, 2012
### andrien
Time will slow down as it's speed increases(proper time)
5. Nov 25, 2012
### SecretSnow
Why is it that for massless particles, E=pc? How do I prove this? Isn't that for particles with rest mass not equal to zero only?
6. Nov 25, 2012
### SecretSnow
And how can a massless particle have momentum? If relativistic momentum is = gamma*m0*v, then shouldn't it be 0? In this case if the speed is c we have 0/0 which is undefined.
7. Nov 25, 2012
### Blackforest
Perhaps because, in totally opposition with the academic position, mass itself is not coming from a speed greater than 0 (which is our custumized view point on the earth), but from a speed smaller than c... (which would be a viewpoint from a passenger traveling with the ligth or with the expanding universe)?
Just a poetic proposition.
8. Nov 25, 2012
### Staff: Mentor
Relativistic momentum is only gamma * m0 * v for a particle with nonzero m0. The more fundamental relation is the one mfb posted:
$$E^2 = m_0^2 c^4 + p^2 c^2$$
which works for both massive particles and massless particles. If $m_0 = 0$, the above relation just gives $E = pc$, which is what mfb and jtbell already gave you as the correct formula for the momentum of a photon.
9. Nov 25, 2012
### SecretSnow
In this case, how do I find the correct value of p? Do I have to use E=hf=pc? Or is there an even more direct way? Thanks a lot!! I think I'm getting there already!!
10. Nov 25, 2012
### Staff: Mentor
Correct value of p for what?
E=hf=pc is fine if you know E or f. If not, you need some other way to determine one of those 3 quantities.
11. Nov 25, 2012
### Staff: Mentor
If you know E for a massless particle, you automatically know p from E = pc.
12. Nov 25, 2012
### UglyNakedGuy
sorry to be an idiot here, how did u put v into the second equation...i mean algebraically
13. Nov 25, 2012
### Staff: Mentor
IMO this is easier to show using my version:
$$\frac{pc}{E} = \frac{v}{c}$$
Start with the usual equations for relativistic momentum and energy: $p = \gamma mv$ and $E = \gamma mc^2$ (where $\gamma = 1 / \sqrt{1 - v^2/c^2}$). Substitute these into the left side of the equation above, and cancel whatever you can cancel.
14. Nov 25, 2012
### UglyNakedGuy
I wish I could start my university again with a different course...
thank you :D i got it
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# Backpropagation through time
"BPTT" redirects here. For the running events originally known as the Bushy Park Time Trial, see parkrun.
Backpropagation through time (BPTT) is a gradient-based technique for training certain types of recurrent neural networks. It can be used to train Elman networks. The algorithm was independently derived by numerous researchers[1][2][3][4]
## Algorithm
To train a recurrent neural network using BPTT, some training data is needed. This data should be an ordered sequence of input-output pairs, $\langle \mathbf{a}_0,\mathbf{y}_0 \rangle, \langle\mathbf{a}_1,\mathbf{y}_1 \rangle,\langle\mathbf{a}_2,\mathbf{y}_2\rangle,...,\langle\mathbf{a}_{n-1},\mathbf{y}_{n-1}\rangle$. Also, an initial value must be specified for $\mathbf{x}_0$. Typically, the vector with zero-magnitude is used for this purpose.
BPTT begins by unfolding a recurrent neural network through time as shown in this figure. This recurrent neural network contains two feed-forward neural networks, f and g. When the network is unfolded through time, the unfolded network contains k instances of f and one instance of g. In the example shown, the network has been unfolded to a depth of k=3.
Training then proceeds in a manner similar to training a feed-forward neural network with backpropagation, except that each epoch must run through the observations, $\mathbf{y}_t$, in sequential order. Each training pattern consists of $\langle\mathbf{x}_t,\mathbf{a}_t,\mathbf{a}_{t+1},\mathbf{a}_{t+2},...,\mathbf{a}_{t+k-1},\mathbf{y}_{t+k}\rangle$. (All of the actions for k time-steps are needed because the unfolded network contains inputs at each unfolded level.) Typically, backpropagation is applied in an online manner to update the weights as each training pattern is presented.
After each pattern is presented, and the weights have been updated, the weights in each instance of f ($f_1, f_2, ..., f_k$) are averaged together so that they all have the same weights. Also, $\mathbf{x}_{t+1}$ is calculated as $\mathbf{x}_{t+1}=f(\mathbf{x}_t, \mathbf{a}_t)$, which provides the information necessary so that the algorithm can move on to the next time-step, t+1.
## Pseudo-code
Pseudo-code for BPTT:
Back_Propagation_Through_Time(a, y) // a[t] is the input at time t. y[t] is the output
Unfold the network to contain k instances of f
do until stopping criteria is met:
x = the zero-magnitude vector;// x is the current context
for t from 0 to n - 1 // t is time. n is the length of the training sequence
Set the network inputs to x, a[t], a[t+1], ..., a[t+k-1]
p = forward-propagate the inputs over the whole unfolded network
e = y[t+k] - p; // error = target - prediction
Back-propagate the error, e, back across the whole unfolded network
Update all the weights in the network
Average the weights in each instance of f together, so that each f is identical
x = f(x); // compute the context for the next time-step
BPTT tends to be significantly faster for training recurrent neural networks than general-purpose optimization techniques such as evolutionary optimization.[5]
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# CORVIZ
Title: O'Brien (n.Greeves), Anne to O'Brien, Joseph Sinton, 1842
ID6113
CollectionThe Transatlantic Letters of an Irish Quaker Family_1818-1877 [B. Jackson]
Filequaker/128
Year1842
SenderO'Brien (n.Greeves), Anne
Sender Genderfemale
Sender Occupationhousewife
Sender ReligionQuaker
OriginCollins, Lake Erie, NY, USA
DestinationNYC, USA
RecipientO'Brien, Joseph Sinton
Recipient Gendermale
Relationshipmother-son
Source
Archive
Doc. No.
Date
Partial Date
Doc. Type
Logunknown
Word Count4096
Genresending money, farm produce and cattle, news of family, friends and neighbours, Quaker meeting, wishes him well at work, bad state of Ireland, correspondence
Note
TranscriptCollins 24 of 7th month 1842 first day morn
My Dear Joseph
We duly received thine of 7lh mo 10lh & 14th to Father, TW and I on 6* day evening and now hasten to answer
it according to request. I need hardly say we were all glad to hear once more from thee and that thee was well, and
we think getting along well when thee is intrusted with the inspection of such large quantities of grain to have been
so raw an hand as thee was; but practice makes perfect, I suppose.
When we read the fore part of thy letter we were felt sorry thee had asked A. for any money, as it seemed too
soon, but when he read that part to me, Father said that thee had done the best \to?\ let A. know thee did not want
to spend thy time for nothing... as likely thee mentioned we had enough for thee to do at home, or some thing
else made him get such a notion into his head about thee disliking to stay. But now thee knows what to depend
on and us told, and thee will find thee will have to be very economical to spare us any thing - and we never
wanted it more as we owe here and there a little, thee knew before thee left, and there is no money to be had. Father
is going out to night with S.Lewis with a little butter and ... two calves we have been fatting, to try to get some
money and a little flour. The money was for Thos as he has never been paid. And now we conclude it best for thee not to send any money at present, and if Tho' has any payments to make in the City we will let him call on thee or write thee again who to pay it to for him; and we will be glad to do the same with [Kerr?] and Bigalow as we are in debt to them all. And the produce of our Cows is not going to amount to much
this season - they came in so late and butter is only worth from 7 to 8 cents per lb. This summer we lost our best
cow, good old Cherry, in 6th month: she died of murrain: she could not be saved, she was taken so violently and
being in good order it was worse for her. She had a calf 2 days old when she was taken; every thing was done for
her that could be, but to no effect. She is a great loss. While I am speaking about the cows, I must tell thee which
of the heifers are the best: the black first, the Brinnl [brindle?] next and then the spotted one and I believe the red
and Brock come last. Thee will wonder Father sometime wishes he had sold her to J. G. as cows can be bought
for 133, 3 year old steers for 30$, oxen good from 50/55$ to 60$, very good 65/70$ and every thing else in
proportion. We will have to sell one of the horses or the steers as we cant keep them all. S. Jennings offer[ed]
Father 70$for Pompy to pay in a year with a little this summer, but Father wanted 75 and more money down as it was for sake of the money he was going to sell him. But he has grown a great fellow since, and he will be a valuable [saleable?] horse any time if we could afford to keep him. As thee reels interested about all we have got, I must tell thee what nice pigs them turned out to be we had of S. Conger. After running in the woods last winter they wd each weigh I dont know how much, but I expect 12 hun[.?] apiece and this summer they about hold their own on grass with a little milk; but come to feed, then by and bye we expect they will grow enormously as they did in the winter. We have got two pigs just like them and Father says they wd weigh 40 to 60 lbs a piece now and they are only little better than 2 months old. Our sow lost her pigs and we got these of[f] [Joseph] Manchester when a few days old. Father has just begun to make hay a day or two ago, or at least cut paths to, and he finds grass much better than he expected; and it w^ still be better if he could leave it a while longer, but he has to begin sooner than if he had more help as he intends making out with Tho' and the boys. Many complaining of their grass being light. Father ... and the piece adjoining with spring wheat, which looks well. The winter wheat through the country hurt very much with the frost, and now with the rust: John S will not have Vi a crop on a large field he has. Our corn is almost a complete failure, as after such cold weather it came rainny and lasted untill it was too late for corn to come to any thing. It will be a great disappointment to us. E [Father] is almost ready to go to the west again: there is talk of a great many going. Ah ram Tucker has been to see Charles and tells fine things of his [cousin?]. He saw most of our acquaintances that have gone there and they are all doing well, among the rest Stephen and Armida. Abram will sell and go and take all his children if he can. Tho' and Maria say they mean to go. Chauncy Rose has sold and gone out to find a place, I believe. John Pekins [Pickens] has sold to Tim Russel679 and says he is going there. G [McMillen] & Mary Ann go when the[y] can, they say. George has sold his farm: Hugh gets the part next his, with the buildings, and Aunt Lydia gets the other, I understand for Moses, and she is coming up to live on it so we will have her for a neighbour. G & M Ann was here yesterday. G is very much drove for money to pay his old debts: some think his taking his Father farm will finish him. He keep & hired man and woman, but they cant do without them now, but he had the man all winter besides hiring Mordaca [Mordecai] Sherman'190 to cut his wood. G is dashing away just what suits him, speculating now and again in horses and oxen. While here yesterday he left his horses fasten[ed] out at the bars[?] as he had been up to Andrew H after having M. Ann, and he had got G [probably George, son of Levi] Woodwards buggy. Well, while there [as he wd not bring them in?] they got lose and they ran away with the buggy and before they got to Sams they dashed it all to pieces ... he had given S. Conger a 70 Dollar yoke of [oxen?] for this spring, came dash up against a large stump and almost killed himself. He came with such force that he tumbled on his back and tolled over, and there he stood when they went to him. We have not heard from him to day but expect he left him down at his old place, as he was hardly able to go when he took him away. The other was a colt that he got with the farm and he had broken it. G felt very bad: they think the buggy is not worth repairing as both the axletree[s] are broken, the tung [tongue] and one of the springs. Father enjoy'd himself at year mg and was not sorry we went and was well while he was gone; and the children done well, as Maria used to come home every night. I felt easy about them. I mean to have Father go more if I can; he wd have gone to quarterly meeting but Wm was not well and the girls and Thos were going; but Thos wd have staid at home as he goes every summer and let Father go, but we could not feel easy; so he had me go as he could make out for a few days well enough. Still I did not expect to go untill the day before, but I went to and we had an agreeable time. Elizabeth Newport attended: she is from Pens [Pennsylvania], Also Pliny Saxton's wife from Palmyra. We went to Charles Neatyard[?] and his sisters and had an agreeable visit. Elisha Freeman's health is poor, not thot to last long. Of our own country, it is pretty ... at present. Wing ... [Preston] is gone: he was burried about two weeks ago yesterday. We attended his funeral and the day before old [Smith?] that.... was buried. Her death was caused by being thrown from a light waggon while from home in Perryburgh [Perrysburg NY]. She died immediately. The horse took fright and the old man could not hold him; so the conscience was he can away and some of the harness give way and caused the wagon to turn over, and she was under it. When all was over she was only heard to speak once; it was expected it was her head that was hurt. Joseph Palmerston has been very ill but has got well again, I expect, as it is some time since. Marias 4 months is out and has taught one week towards another mo.: she looks thin but is well. We are all in usual health. When Father works a little too hard, is sure to have his old complaint come on; yet he has been better than usual as I make him hemlock tea to drink that he thinks has done him good. Its likely you have got Rebecca home by this time and so cousin Phebe is making you a visit. She used to be lively when a girl but I never thot she looked the least like me. I guest [guessed] who it was before I came to her name: thee must have [wondered?] who she was before thee saw her, from James descriptions of her. They used, to think her too talkative in Phila and I find she dont lose any of it, from thy acct. I hope she wont tire Abram out. I never tho1 much of her, but then thee not say any thing. Mary Greeves told us of her [Phoebe's] Mothers death. I wd like to hear what she had to say of thee or to thee, as she used to say thee was the hadsomest [handsomest?] baby she ever saw. I think she must allow thee has grown some. If nothing more, its likely she inquired of thee about Jacob Taylor's affairs. Well, the heirs does not expect to have much left, if any at all. Caleb has sued for ... and is likely to get about 1600$ besides his share; but Phebe,
the woman that kept house for Jacob, has commenced a suit against the estate and if she recovers it, with a loss of
10,000\$ in bank that has failed, there cant be much left. Give my love to Cousin Phebe and tell I should like very
much to see her and here [bear] from Bersy Tracy (Mary's Mother); and that I have often been asked about her
within this 20 years, how P. Sin ton was and if she was married yet. She'll likely make Mary Beale a visit as she did
the last time she was in New York, Maria says. We wd like to be remembered to J. Beale's family. Dont thee find
the Irish people a very agreeable people to be acquainted with, far before the Americans in general.
The boys are all glad to here from thee and when a letter comes we have to wait untill they get ready to come in
and sit down to hear it, just as we used to do when Maria was gone. It pleases the little boys to be noticed. Father
find[s] them of... [great?] use this summer. Thos keeps well but cant do heavy work; but he has held the drag or
cultivator in doing the corn and potatoes, and ridged for ruatabaga’s down at the bridge and such work that saves
Father a good deal; and he has planted and hoed with the rest. Still, he looks thin but keeps well. Margaretta
grows tall: she will soon be as tall as Maria. She and Wm went to school fore part of summer, but one thing or
another has hindered her of late. But I expect her to go some more as it is a pity to keep Wm G at home as he learns
pretty well: he is in 2 syllables. He often tells us when not writing he must send a kiss to Joseph as he sent one to
him; and the little boys will say, well, I would like to know what Joe is about.
Well, I chink thee must get a thorough knowledge of business - thee is intrusted so much with large things -
and we do hope thee will still persevere in thy endeavours to keep in A & James's favour for, as M [Maria] says,
where James takes a liking it will be permanent unless it is thy fault. I expect it does seem a good deal to pay thee,
a beginner, when they could get good hands for nothing as it were; still I think they can place mote confidence in
thee than every one and M thinks thee must save James agreat deal of running about, as the girls used to speak of
him a great deal and how much tunning he had. How does thee like him or has thee got acquainted with him yet:
for business men is just what thee says of him; when they are attending to their business they cannot nor will not
attend to any thing else. So that thee not mind if he does not be conversant in the office.
Thee does not mention any thing about our Irish friends in this last letter. We received thy letter to Maria after
we had given our letter to G F White or we should have answered; but how it got there we could not tell, as I found
it in one of the Committee rooms, tucked into a string that surrounded a packet that was directed to Canada. I
should not have found [it], only Nathaniel Potter happened to see it there. We expected likely J Wattins [Watkins?]
[at?] yearly meeting and we were sorry we had not got it sooner, but I think if he was there he might or did inquire
if there was any there from Collins. His [he] is a distant cousin to Father.
We have had so much rain this summer that the creek has cut up the road beyond the bridge so as to make it
impassible at times; and they had to get on [to] the commissioner to see about helping them fix it. And finely
[finally] they have concluded to have them turn the course of the creek and have it run beyond the present bridge, and build a bridge 24 feet in the span and to till up where the old one is now with logs &c &c. Well, while there
they got them to say where the road on the hill muse run: so after some time they conclude that where Father
wanted was the best place and so run in on Sam's. So Burk went to work to Make it out and, while busy, Sam went
home leaving word with one of the neighbours to tell Burk not to go on to his land. But B. persevered and staked
it out, but told Father to get all agreed and lay it where they thot best and they wd come on again. But Sam is
innoinable [immovable?] altho he told Burk that he might go on his land if it was thot best. Now yesterday they
happened along again and they left word with John Goodell they might continue the present road on to that point
of the Hemlock [?] knoll that you used to talk about, and so they are all satisfied. We here and our west neighbours
the Shermans and others are coming on and the make a bee [combined endeavour] to work down the knoll so as
to bring down to the new bridge they are Co make. So I am in hopes we will have all completed and that they all
will be satisfied, so that we shall know which is our Road or not and not have Sam forever sputtering [?].
Maria is writing to Phia to Sally Ann [Fling}. She has just had a letter from her: all well, his letter has nothing
in them to interest us, such as Marriages and death of folk we no nothing about and how much they wd like to see
het &c &c. She has not had any in some time before. I wrote a ... long letter to Cousin James in the Spring, let
him know how much we had done and what little prospect there was of Father getting it done at present, as rimes
were bad and his health bad, but mat when he could he meant to work at it. Which he does this fall for he ought
to get it up, but, as stock is, we could not finish it with what we have, if it was all sold, and pay out debts too.
We see shocking ace" from Ireland in them last papers thee sent. What a distressed state they ate in and there
are a great many coming ... I tried to have Father write for that Irish man thee wanted to send, but he tho' we
could not board him at any rate, as we have to buy our bread stuff and Potatoes. We are in hopes of having enough
of Potatoes this year as they look well but our ... are nothing as they have been so backward ... Bigalow or Frank
and I done know but both start ... week for Phia with a drove of Cattle. Frank got the number of the office from
Thos as he expect to come by the way of N. York home. He is going such a round, he tho' it was not best to carry
a letter, so that thee will likely see him as he intends calling.
We have concluded that it is best for thee not to send the New World any longer, as it must cost thee
considerable. And if thee can send us a political one once in a while without ex pence, even if it is a few days old,
we wd be glad to see it as we dont take the Buffalo paper now. But we know these papers and out letters must cost
thee considerable and we want thee to Save all thee can. Yet they furnish us a good deal of reading, but then we
w11 not wish thee to send them any longer.
Thee must enjoy thyself very much when in the country as thee has always lived in, but we ate glad thee does
not go any where without acquainting A. of it and that thee goes to meeting and conduct thy self Soberly. Thee
will always be thought more of and confided more in than those that behave like Larry did. A. gives thee as much
as thee could at all expect, for thee must consider he has only taken thee as an apprentice and what they allow in
such a case is merely what they think thy clothes will cost; and thee may see A tho1 that perhaps thee wd want it
all, so advised thee not to send much home. Thee see, he w11 not want thee to go in debt to them, nor we either,
for fear something turning up that thee wd have to have; and I do hope A. is willing thee should stay, for if he is
not and thee knows it, I wd not want [thee] to stay and be a burthen to him, for there is enough to do in the
country. But I'm afraid thee has felt too independant for A: thee must study him and try to please him in every
thing, for he grows old [64] and harder to please. When thee write, say if he still feels satisfied to keep thee or if
he still treats thee kindly, for I wd be sorry to have thee stay against his will. Thee cant tell whether they were
disappointed in thee or not, or whether thee knows more about business than they expected.
I had to write as they rest [do] not [have] time. Maria will write next, and as we want money and cant do an [
... ] other way we will call on thee to that amount at any rate, but I hope thee want any mote clothes now for so
... and keep a regular acct of everything, so that thee have it if call[ed] on or can give an acct of... thee has had at
any time. I must bring this to a close as I have to go get Father some provision ready to go to Buffalo with, and I
wanted to send this by him: it will save thee [6cents?].
A. Varney give Father credit for 1 Dollar on his ace': thee does not say thing about his writing to thee. When
Thos has an oppertunity he will write, but what a pity he is such a bad speller and It affronts him to tell him of it.
I think[?] I will have him study the spelling book this winter and give him out sentences to write on a slate, so as
to learn him how to spell. The boys learned well last winter. I suppose thee does not here often from our friends
in Phila we have not lately except thro Sally Ann: they ate well.
I wrote to Aunt Susanna to write to thee and if she does, thee be sure answer it. Thee need not be sp ... for
they wd make allowance for chee. I wonder Aunt Jane do not answer my letter. Her husband is in partenership with Thos Richardson Father, I expect. The family of R. used to feel themselves above us, we used to think, but i: is
only as regards property, I suppose. Thos [Richardson] is settled in the city - does he visit in the family.
Well I cant think of any thing more and in hopes thee can make this all out I will say fare well, wishing thee to
remember us to Abram and the girls, in which we are joined by Maria and remain
thy ever afft Mother
A O'Brien
P.S. Did thee know that Father wrote to A: thee ... [need] not say any thing to him about it, as likely he will
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ja037787o_si_002.cif (15.95 kB)
# Mechanisms of Exchange Modulation in Trimethylenemethane-type Biradicals: The Roles of Conformation and Spin Density
dataset
posted on 17.12.2003, 00:00 by David A. Shultz, Rosario M. Fico,, Hyoyoung Lee, Jeff W. Kampf, Kristin Kirschbaum, A. Alan Pinkerton, Paul D. Boyle
The molecular structures and magnetic properties of six dinitroxide biradicals are described. Five of the dinitroxides are trimethylenemethane-type (TMM-type) biradicals; that is, the intramolecular exchange parameter, J, is modulated by a carbon−carbon double bond. However, the efficacy of the carbon−carbon double bond as an exchange coupler is determined by the molecular conformation. Our results show that the exchange parameters correlate with phenyl-ring torsion angles (φ) via a simple Karplus−Conroy-type relation: J = 44 cos2 φ − 17. Comparison of these results to those obtained for our isostructural series of bis(semiquinone) biradicals shows that both the magnitude of J and the resistance of ferromagnetic J to bond torsions is proportional to the spin density adjacent to the exchange coupler.
## Exports
figshare. credit for all your research.
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Nonlinear circuit and RLC
I'm trying to solve the following question from "Communication Circuits: Analysis and Design" by Donald T. Hess:
For the circuit shown in Fig. $$\1.P1\$$, determine an expression for $$\v_o(t)\$$(Q1 and Q2 are identical).
My try: Q2 and Q3 form a current mirror. We can determine the current $$\I_{C2}\$$ which is equal to $$\I_{E1}\$$ since $$\1\mu F\$$ capacitor is an ac short circuit(So here are we assuming that ac and dc analysis are separable? But I think this is true only for linear circuits). Since Q2 and Q3 are identical,
$$\frac{0 - (-10+V_{BE})}{2} = \alpha I_E + \frac{2I_E}{\beta + 1}$$ $$\alpha = \frac{\beta}{\beta + 1}$$
Which leads to $$I_E = \frac{99\times 4.65}{100} \implies I_C = \frac{99}{100}\times \frac{99\times 4.65}{100} \approx 4.557mA$$ At this point we should use $$i_E = I_{ES} e^{\frac{v_{BE}}{x}} \\ x = \frac{kT}{q} \approx 26mV$$ I think $$\v_{BE} = -V_{dc} -v(t)\$$ but according to the solution because of the capacitor there is no dc voltage. Is this really correct? If we accept my expression for $$\v_{BE}(t)\$$, we have $$i_E = I_{ES}e^{\frac{-V_{dc}}{x}}e^{\frac{-v(t)}{x}} = I_pe^{-10\cos\omega t} \\ I_p = I_{ES}e^{\frac{-V_{dc}}{x}}$$ Using the Fourier series we have $$e^{-10\cos \omega t} = I_0(10) + 2\sum_{n = 1}^{\infty}(-1)^n I_n(10) \cos (n\omega t)$$ Where $$\I_n(x)\$$ is the modified Bessel functions. The biasing circuitry demands $$I_pI_0(10) = 4.557 \times 10^{-3} \implies I_p = \frac{4.557 \times 10^{-3}}{I_0(10)} \approx 1.6 \times 10^{-6}$$ Since $$\i_C = \alpha i_E\$$ the output voltage should be $$v_o(t) = 10 - \alpha I_p (I_0(10)Z_L(j0\omega) + 2\sum_{n = 1}^{\infty}(-1)^n I_n(10)Z_L(jn\omega) \cos (n\omega t))$$Where $$\Z_L(jn\omega)\$$ is the impedance of the parallel RLC at harmonics. The impedance of the RLC circuit to dc is zero and the resonance frequency is $$\omega_0 = \frac{1}{\sqrt{LC}} = 3\times 10^7$$ Assuming $$\\alpha \approx 1\$$ the answer should be $$v_o(t) \approx 10 - 3.2\times 10^{-6}(-I_1(10)Z_L(j\omega)\cos(\omega t) + I_2(10)Z_L(j2\omega)\cos(2\omega t)-I_3(10)\times 10^3\cos(3\omega t))$$From the table we know that $$\I_3(10) = 1758.4\$$ which implies the third term is $$-5.62\cos(3\times 10^7 t)$$and we can determine other terms. One solution manual gives $$v_o(t) \approx -0.155\cos (\omega t) + 0.424\cos(2\omega t) - 5.45\cos(3\omega t)$$And Hess's book gives $$v_o(t) \approx -0.28\sin(10^7 t) + 7.3\cos(2\times 10^7 t)+0.33\sin(3\times 10^7 t)$$The first answer seems very close to my answer but there is no $$\10\$$ dc voltage in the final answer. The second answer differs considerably from my answer. So what's the correct answer?
Here is the summary of the problems:
1. Are we assuming that ac and dc analysis are separable? If yes, why is this possible? Obviously the circuit is nonlinear and superposition doesn't hold.
2. Is there a dc voltage across BE junction?
3. Is my final answer for the $$\v_o(t)\$$ correct?
• The Hess answer is certainly wrong with the high Q near the 3rd harmonic and similarity, I would expect the 2nd harmonic more than the fundamental at this level input of distortion. At 4.6mA Vbe will be around 630 mV with the input at 520 mVpp is a massive amount of distortion Mar 1 at 0:15
• @TonyStewartSunnyskyguyEE75 Thanks. So there is a dc voltage across BE junction, right? Mar 1 at 0:29
• Remember/verify that Vbe =600 mV @ Ic=1mA and this uses a current mirror to Ic and Voltage source AC is 0 Ohms driving a low impedance common base so Vbe is modulated which modulates Ic with asymmetric exponential current. Mar 1 at 1:41
• The common base has an output impedance of rE/hFE since there is no base resistance which makes it , I guess <<1 Ohm so a true voltage source is used and 1uF is low enough above1MHz. This forces Vbe changes directly and that forces the exponential current swings with large modulation of the input voltage. the collector load is tuned above the 3rd harmonic so there is a high slope of gain on the harmonics up to the 3rd then attenuated as the 4th is on the down slope of the resonant filter and so on, You did a decent job with your method, but there is more to it. Such as temperature effects. Mar 1 at 3:08
• Bulk resistance will also factor into this with different chip sizes so I did not do the math, but your approach is good enough unless you want to simulate with different devices. I have never used this circuit as I don’t see the benefit of such non-linearity with an off-tuned filter. They let you assume Vbe=0.7 For simplicity but I always found 1mA is always closer to 600mV and this uses 4.6mA yet >10mA would be all over the map with a wide range of bulk resistance, on different devices. So I estimated 630 mV from experience. I’m not a teacher, but I would give full marks. Mar 1 at 3:19
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Exercise 17.3
Select a specific member of the set of policies that are optimal for $R(s)>0$ as shown in Figure sequential-decision-policies-figure(b), and calculate the fraction of time the agent spends in each state, in the limit, if the policy is executed forever. (Hint: Construct the state-to-state transition probability matrix corresponding to the policy and see Exercise markov-convergence-exercise.)
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Volume 358 - 36th International Cosmic Ray Conference (ICRC2019) - NU - Neutrino
Neutrinos from Primordial Black Hole Evaporation
P. Dave,* I. Taboada on behalf of the IceCube Collaboration
*corresponding author
Full text: pdf
Pre-published on: July 22, 2019
Published on:
Abstract
Primordial Black Holes (PBHs) are candidates for dark matter as well as ultra-high energy cosmic rays. PBHs are speculated to exist over a large range of masses, from below $10^{15}$ g to $10^3$ M$_\odot$. Here we search for PBHs with an initial mass of $\sim 10^{15}$ g. Hawking radiation by black holes of this initial mass predicts their evaporation at present time. PBHs are expected to produce copious amounts of high-energy neutrinos and gamma rays right before evaporating. Gamma-ray instruments such as Fermi, VERITAS, HAWC, HESS, and Milagro have conducted searches for evaporating PBHs during their last second to a year of existence. They are able to detect bursts from PBHs in a range of $10^{-3}$ to $0.1$ pc. We present sensitivity to PBH evaporation using one year of neutrino data by IceCube. In these proceedings, we detail the changes to adapt IceCube's standard neutrino flare search, aka time-dependent point source search, into one that is appropriate for evaporating BHs. These proceedings serve as proof of concept for a first-ever search for evaporating PBHs using neutrinos that can use 10 years of IceCube data.
DOI: https://doi.org/10.22323/1.358.0863
How to cite
Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.
Open Access
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# 3.2 Independent and mutually exclusive events (modified r. bloom) (Page 2/4)
Page 2 / 4
Roll one fair 6-sided die. The sample space is $\mathrm{\left\{1, 2, 3, 4, 5, 6\right\}}$ . Let event $A$ = a face is odd. Then $\mathrm{A = \left\{1, 3, 5\right\}}$ . Let event $B$ = a face is even. Then $\mathrm{B = \left\{2, 4, 6\right\}}$ .
• Find the complement of $A$ , $\mathrm{A\text{'}}$ . The complement of $A$ , $\mathrm{A\text{'}}$ , is $B$ because $A$ and $B$ together make up the sample space. $\text{P(A) + P(B) = P(A) + P(A') = 1}$ . Also, $\text{P(A)}=\frac{3}{6}$ and $\text{P(B)}=\frac{3}{6}$
• Let event $C$ = odd faces larger than 2. Then $C=\left\{3,5\right\}$ . Let event $D$ = all even faces smaller than 5. Then $D=\left\{2,4\right\}$ . $\text{P(C and D)}=0$ because you cannot have an odd and even face at the same time. Therefore, $C$ and $D$ are mutually exclusive events.
• Let event $E$ = all faces less than 5. $E=\left\{1,2,3,4\right\}$ .
Are $C$ and $E$ mutually exclusive events? (Answer yes or no.) Why or why not?
No. $C$ = $\mathrm{\left\{3, 5\right\}}$ and $E$ = $\mathrm{\left\{1, 2, 3, 4\right\}}$ . . To be mutually exclusive, must be 0.
• $\text{Find P(C|A)}$ . This is a conditional. Recall that the event $C$ is $\mathrm{\left\{3, 5\right\}}$ and event $A$ is $\mathrm{\left\{1, 3, 5\right\}}$ . To find $\text{P(C|A)}$ , find the probability of $C$ using the sample space $A$ . You have reduced the sample space from the original sample space $\mathrm{\left\{1, 2, 3, 4, 5, 6\right\}}$ to $\mathrm{\left\{1, 3, 5\right\}}$ . So, $\text{P(C|A)}=\frac{2}{3}$
Let event $G$ = taking a math class. Let event $H$ = taking a science class. Then, = taking a math class and a science class. Suppose $\text{P(G)}=0.6$ , $\text{P(H)}=0.5$ , and $\text{P(G AND H)}=0.3$ . Are $G$ and $H$ independent?
If $G$ and $H$ are independent, then you must show ONE of the following:
• $\text{P(G|H)}=\text{P(G)}$
• $\text{P(H|G)}=\text{P(H)}$
• $\text{P(G AND H)}=$ $\text{P(G)}\cdot \text{P(H)}$
The choice you make depends on the information you have. You could choose any of the methods here because you have the necessary information.
Show that $\text{P(G|H)}=\text{P(G)}$ .
Show $\text{P(G AND H)}=$ $\text{P(G)}\cdot \text{P(H)}$ .
## Interpretation of results
Since $G$ and $H$ are independent, then, knowing that a person is taking a science class does not change the chance that he/she is taking math. (Note: IF the two events had not beenindependent - that is, IF they were dependent - then knowing that a person is taking a science class would change the chance he/she is taking math. The next example will illustrate two events that are not independent.)
In a particular college class, 60% of the students are female. 50 % of all students in the class have long hair. 45% of the students are female and have long hair. Of the female students, 75% have long hair. Let F be the event that the student is female. Let L be the event that the student has long hair.Are the events of being female and having long hair independent?
• The following probabilities are given in this example:
• $\text{P(F )}=0.60$ ; $\text{P(L )}=0.50$
• $\text{P(F AND L)}=0.45$
• $\text{P(L|F)}=0.75$
If $F$ and $L$ are independent, then the following conditions are true. BUT if you show that any of the conditions are not true , then $F$ and $L$ are not independent .
• $\text{P(L|F)}=\text{P(L)}$
• $\text{P(F|L)}=\text{P(F)}$
• $\text{P(F AND L)}=$ $\text{P(F)}\cdot \text{P(L)}$
The choice you make depends on the information you have. You could use the first or last condition on the list for this example. You do not know P(F|L) yet, so you can not use the second condition.
## Solution 1
Check whether P(F and L) = P(F)P(L): We are given that P(F and L) = 0.45 ; but P(F)P(L) = (0.60)(0.50)= 0.30 The events of being female and having long hair are not independent because P(F and L) does not equal P(F)P(L).
## Solution 2
Check whether P(L|F) equals P(L): We are given that P(L|F) = 0.75 but P(L) = 0.50; they are not equal. The events of being female and having long hair are not independent.
## Interpretation of results
The events of being female and having long hair are not independent; knowing that a student is female changes the probability that a student has long hair.
In a box there are 3 red cards and 5 blue cards. The red cards are marked with the numbers 1, 2, and 3, and the blue cards are marked with the numbers 1, 2, 3,4, and 5. The cards are well-shuffled. You reach into the box (you cannot see into it) and draw one card.
Let $R$ = red card is drawn, $B$ = blue card is drawn, $E$ = even-numbered card is drawn.
The sample space . $S$ has 8 outcomes.
• $\text{P(R)}=\frac{3}{8}$ . $\text{P(B)}=\frac{5}{8}$ . $\text{P(R AND B)}=0$ . (You cannot draw one card that is both red and blue.)
• $\text{P(E)}=\frac{3}{8}$ . (There are 3 even-numbered cards, $\mathrm{R2}$ , $\mathrm{B2}$ , and $\mathrm{B4}$ .)
• $\text{P(E|B)}=\frac{2}{5}$ . (There are 5 blue cards: $\mathrm{B1}$ , $\mathrm{B2}$ , $\mathrm{B3}$ , $\mathrm{B4}$ , and $\mathrm{B5}$ . Out of the blue cards, there are 2 even cards: $\mathrm{B2}$ and $\mathrm{B4}$ .)
• $\text{P(B|E)}=\frac{2}{3}$ . (There are 3 even-numbered cards: $\mathrm{R2}$ , $\mathrm{B2}$ , and $\mathrm{B4}$ . Out of the even-numbered cards, 2 are blue: $\mathrm{B2}$ and $\mathrm{B4}$ .)
• The events $R$ and $B$ are mutually exclusive because $\text{P(R AND B)}=0$ .
• Let $G$ = card with a number greater than 3. $G=\left\{\mathrm{B4},\mathrm{B5}\right\}$ . $\text{P(G)}=\frac{2}{8}$ . Let $H$ = blue card numbered between 1 and 4, inclusive. $H=\left\{\mathrm{B1},\mathrm{B2},\mathrm{B3},\mathrm{B4}\right\}$ . $\text{P(G|H)}=\frac{1}{4}$ . (The only card in H that has a number greater than 3 is $\mathrm{B4}$ .) Since $\frac{2}{8}=\frac{1}{4}$ , $\text{P(G)}=\text{P(G|H)}$ which means that $G$ and $H$ are independent.
what is variations in raman spectra for nanomaterials
I only see partial conversation and what's the question here!
what about nanotechnology for water purification
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how did you get the value of 2000N.What calculations are needed to arrive at it
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# How many times does the earth rotate per year?
Assuming there are exactly $$365$$ days per year. How many rotations about its axis does the earth make in one year?
• @RewanDemontay eh, I'm kinda on the fence. It definitely has a "single definitive answer", but might be considered "textbook". – Hugh Apr 10 at 22:51
• Our guiding principle is roughly presented here - Are math-textbook-style problems on topic? - the general idea is that a problem with a "Clever or elegant solution, often an "aha" moment; Unexpected problem statement; or Unexpected or counterintuitive result" might be a good puzzle. I'd be inclined to let this pass, given that to folks who have never really thought about it, the result is likely to be surprising. (Having said that, it's trivially solvable without actually resorting to math, making it, well, less puzzle and more trivia.) – Rubio Apr 10 at 23:03
• I also have some sympathy for this question - I have actually thought about posting this riddle, in some form, before but it's difficult to make it sound enticing. Needless to say, the result is not immediately obvious. – hexomino Apr 10 at 23:15
• @hexomino I agree. This was something I actually thought about today and figured out. When I typed it out though, it doesn't seem enticing at all. Maybe someone can transform it into a more wordy puzzle. – Jac Frall Apr 10 at 23:17
• Related puzzle about coin rotating around a set of coins: puzzling.stackexchange.com/questions/56787/… – Presh Apr 11 at 2:36
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# Solving a two variable equation
1. Apr 26, 2012
### mtayab1994
1. The problem statement, all variables and given/known data
For every (x,y) in Z^2 solve : 6x-5y=1
3. The attempt at a solution
I did 6x=5y+1 and then i said let x=5n+1 so then we get 6(5n+1)=5y+1 and that gives that y=6n+1 so the solution is (5n+1,6n+1). Is this the correct way of solving this?
2. Apr 26, 2012
### ehild
I do not quite follow your way of thinking but the result is correct.
I would say that 6x-5y=5(x-y)+x=1, x=1+5(y-x) and let n=y-x (integer)
Then x=5n+1, and substituting for x into the original equation (as you did), it follows that y= 6n+1.
ehild
3. Apr 26, 2012
### mtayab1994
Yes, that's a clever way that you did. You can also work with congruences .
6x Ξ 1(mod5) and split up the 6x into 5x+x and then you'll be left with x Ξ 1(mod5).
Is that correct as well??
4. Apr 26, 2012
### HallsofIvy
Staff Emeritus
First it is incorrect to say "For every (x, y) in Z2 solve...". It should be simply "For (x, y) in Z2 solve ..."
The simplest way to solve this is to note that 6- 5= 1 so (1, 1) is a solution. Further if we take x= 1- 5k and y= 1+ 6k, 6x+ 5k= 6(1+ 5k)- 5(1+ 6k)= 6+ 30k- 5- 30k= 1 for all k. That is, any (x,y) of the form (1+ 5k, 1+ 6k), for k any integer, which is, of course, the same as your solution, is a correct solution.
5. Apr 27, 2012
### vela
Staff Emeritus
Yes, that's correct.
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One task which I once undertook, was To provide a general-case description, of what the possible shader-types are, that can run on a GPU – on the Graphics-Processing Unit of a powerful Graphics Card. But one problem in providing such a panoply of ideas, is the fact that too many shader-types can run, for one synopsis to explain all their uses.
One use for a Geometry Shader is, to treat an input-triangle as if to consist of multiple smaller triangles, each of which would then be called ‘a micropolygon’, so that the points between these micropolygons can be displaced along the normal-vector of the base-geometry, from which the original triangle came. One reason for which the emergence of DirectX 10, which also corresponds to OpenGL 3.x , was followed so quickly by DirectX 11, which also corresponds to OpenGL 4.y , is the fact that the tessellation of the original triangle can be performed most efficiently, when yet-another type of shader only performs the tessellation. But in principle, a Geometry Shader is also capable of performing the actual tessellation, because in response to one input-triangle, a GS can output numerous points, that either form triangles again, or that form triangle strips. And in fact, if the overall pattern to the tessellation is rectangular, triangle strips make an output-topology for the GS, that makes more sense than individual triangles. But I’m not going to get into ‘Geometry Shaders coded to work as Tessellators’, in this posting.
Instead, I’m going to focus on a different aspect of the idea of micropolygons, that I think is more in need of explanation.
Our GS doesn’t just need to displace the micropolygons – hence, the term ‘displacement shader’ – but in addition, must compute the normal vector of each Point output. If this normal vector was just the same as the one for the triangle input, then the Fragment Shader which follows the Geometry Shader, would not really be able to shade the resulting surface, as having been displaced. And this would be because, especially when viewing a 3D model from within a 2D perspective, the observer does not really see depth. He or she sees changes in surface-brightness, which his or her brain decides, must have been due to subtle differences in depth. And so a valid question which arises is, ‘How can a Geometry Shader compute the normal-vectors of all its output Points, especially since shaders typically don’t have access to data that arises outside one invocation?’
(Updated 07/08/2018, 7h55 … )
## Modern Photogrammetry
Modern Photogrammetry makes use of a Geometry Shader – i.e. Shader which starts with a coarse grid in 3D, and which interpolates a fine grid of microplygons, again in 3D.
The principle goes, that a first-order, approximate 3D model provides per-vertex “normal vector” – i.e. vectors that always stand out at right angles from the 3D model’s surface in an exact way, in 3D – and that a Geometry Shader actually renders many interpolated points, to several virtual camera positions. And these virtual camera positions correspond in 3D, to the assumed positions from which real cameras photographed the subject.
The Geometry Shader displaces each of these points, but only along their interpolated normal vector, derived from the coarse grid, until the position which those points render to, take light-values from the real photos, that correlate to the closest extent. I.e. the premise is that at some exact position along the normal vector, a point generated by a Geometry Shader will have positions on all the real camera-views, at which all the real, 2D cameras photographed the same light-value. Finding that point is a 1-dimensional process, because it only takes place along the normal vector, and can thus be achieved with successive approximation.
(Edit 01/10/2017 : To make this easier to visualize. If the original geometry was just a rectangle, then all the normal vectors would be parallel. Then, if we subdivided this rectangle finely enough, and projected each micropolygon some variable distance along that vector, There would be no reason to say that there exists some point in the volume in front of the rectangle, which would not eventually be crossed. At a point corresponding to a 3D surface, all the cameras viewing the volume should in principle have observed the same light-value.
Now, if the normal-vectors are not parallel, then these paths will be more dense in some parts of the volume, and less dense in others. But then the assumption becomes, that their density should never actually reach zero, so that finer subdivision of the original geometry can also counteract this to some extent.
But there can exist many 3D surfaces, which would occupy more than one point along the projected path of one micropolygon – such as a simple sphere in front of an initial rectangle. Many paths would enter the sphere at one distance, and exit it again at another. There could exist a whole, complex scene in front of the rectangle. In those cases, starting with a coarse mesh which approximates the real geometry in 3D, is more of a help than a hindrance, because then, optimally, again there is only one distance of projection of each micropolygon, that will correspond to the exact geometry. )
Now one observation which some people might make, is that the initial, coarse grid might be inaccurate to begin with. But surprisingly, this type of error cancels out. This is because each microploygon-point will have been displaced from the coarse grid enough, that the coarse grid will finally no longer be recognizable from the positions of micropolygons. And the way the micropolygons are displaced is also such, that they never cross paths – since their paths as such are interpolated normal vectors – and so no Mathematical contradictions can result.
To whatever extent geometric occlusion has been explained by the initial, coarse model.
Granted, If the initial model was partially concave, then projecting all the points along their normal vector will eventually cause their paths to cross. But then this also defines the extent, at which the system no longer works.
But, According to what I just wrote, even the lighting needs to be consistent between one set of 2D photos, so that any match between their light-values actually has the same meaning. And really, it’s preferable to have about 6 such photos…
Yet, there are some people who would argue, that superior Statistical Methods could still find the optimal correlations in 1-dimensional light-values, between a higher number of actual photos…
One main limitation to providing photogrammetry in practice, is the fact that the person doing it may have the strongest graphics card available, but that he eventually needs to export his data to users who do not. So in one way it works for public consumption, the actual photogrammetry will get done on a remote server – perhaps a GPU farm, but then simplified data can actually get downloaded onto our tablets or phones, which the mere GPU of that tablet or phone is powerful enough to render.
But the GPU of the tablet or phone is itself not powerful enough, to do the actual successive approximation of the micropolygon-points.
I suppose, that Hollywood might not have that latter limitation. As far as they are concerned, all their CGI specialists could all have the most powerful GPUs, all the time…
Dirk
P.S. There exists a numerical approach, which simplifies computing Statistical Variance in such a way, that Variance can effectively be computed between ‘an infinite number of sample-points’, at a computational cost which is ‘only proportional to the number of sample-points’. And the equation is not so complicated.
s = Mean(X2) - ( Mean(X) )2
(Next)
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# Homework Help: I don't understand the meaning of f^(39)(pi/2)?
1. Oct 6, 2011
### jrjack
I don't understand the meaning of f^(39)(pi/2)??
1. The problem statement, all variables and given/known data
Find the indicated derivative of f(x)=sin x and evaluate it at x=pi/2.
$$f^{(39)}(\pi/2)=$$
2. Relevant equations
3. The attempt at a solution
I'm not sure what the f^39 means??? And it could be f(39)(pi/2)??? but it looks like f raised to the 39th power???
Is this a common way to express a problem, because I have not seen one like this yet?
I know the derivative of sin x, is cos x, and if x=pi/2, then cos(pi/2)=0
But how should I evaluate the rest of this problem?
If f^(39) makes no sense, then f(39)(pi/2) doesn't make any sense, because x=pi/2???
2. Oct 6, 2011
### physicsnewb7
Re: I don't understand the meaning of f^(39)(pi/2)??
I think they mean take the 39th derivative of sin(x) and evaluate that at pi/2 the 2nd derivative -sin(x) third is -cos(x) and fourth is sin(x)......
Last edited: Oct 6, 2011
3. Oct 6, 2011
### jrjack
Re: I don't understand the meaning of f^(39)(pi/2)??
That makes more sense.
Is there a short cut or should I just change sin and cos (including the negative) 39 times?
4. Oct 6, 2011
### physicsnewb7
Re: I don't understand the meaning of f^(39)(pi/2)??
every fourth derivative gives you sin(x) I think you can take it from there
5. Oct 6, 2011
### jrjack
Re: I don't understand the meaning of f^(39)(pi/2)??
Yes, as I started doing it, I quickly saw sin x after 4 times, and ended up with -cos x = 0.
Thanks.
6. Oct 7, 2011
### Staff: Mentor
Re: I don't understand the meaning of f^(39)(pi/2)??
That's the right value, but what you got was -cos(π/2) = 0.
The notation f(39)(x), with parentheses around the exponent, usually means the derivative of that order. Without parentheses it would just mean raising the function to the indicated power.
7. Oct 7, 2011
### jrjack
Re: I don't understand the meaning of f^(39)(pi/2)??
Thanks for the clarity. Yes for this equation x = pi/2.
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Write each of the following as percentage.(i) 7/25 (ii) 14/625 (iii) 5/8 (iv) 0.8 (v) 5/8 (vi) 0.8
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closed
Write each of the following as percentage.
(i) 7/25
(ii) 14/625
(iii) 5/8 (iv) 0.8
(v) 5/8
(vi) 0.8
(vii) 11 : 80
(viii) 111 : 125
(ix) 13 : 75
(x) 15 : 16
(xi) 0.18
(xii) 7/125
+1 vote
by (6.7k points)
selected by
(i) 7/25
We know that while changing in percentage we have to multiplied by 100, so,
=$\frac{7}{25}\times{100}={28}$%
(ii) 14/625
We know that while changing in percentage we have to multiplied by 100, so,
$=\frac{14}{625}\times{100}=\frac{56}{25}$=2.24%
(iii) 5/8
We know that while changing in percentage we have to multiplied by 100, so,
$=\frac{5}{8}\times{100}=\frac{125}{2}$=62.5%
(iv) 0.8
We know that while changing in percentage we have to multiplied by 100, so,
$=\frac{8}{10}\times{100}$=80%
(iv) 0.8
We know that while changing in percentage we have to multiplied by 100, so,
$=\frac{5}{8}\times{100}$ -62.5%
(vi) 0.8
We know that while changing in percentage we have to multiplied by 100, so,
$=\frac{8}{10}\times{100}$=80%
(vii) 11 :
80 We know that while changing in percentage we have to multiplied by 100, so,
$=\frac{11}{80}\times{100}=\frac{55}{4}$=13.75%
(viii) 111 :
125 We know that while changing in percentage we have to multiplied by 100, so
$=\frac{111}{125}\times{100}=\frac{444}{5}$=88.8%
(ix) 13 : 75
We know that while changing in percentage we have to multiplied by 100, so,
$=\frac{13}{75}\times{100}=\frac{52}{3}$=17.33%
(x) 15 : 16
We know that while changing in percentage we have to multiplied by 100, so,
$=\frac{15}{16}\times{100}=\frac{375}{4}$=93.75%
(x) 15 : 16
We know that while changing in percentage we have to multiplied by 100, so
,$=\frac{18}{100}\times{100}$-18%
(xii) 7/125
We know that while changing in percentage we have to multiplied by 100, so,
$=\frac{7}{125}\times{100}=\frac{28}{5}$=5.6%
|
To start with, a little bit of theory. Each pixel on a photo represents a tiny point, and Photoshop lets you create, cut, copy, and paste tiny bits of that image. The trick is to make those tiny bits look like something they’re not.
If you look at the full-screen Preview at the upper-left corner, you can see the finished image, with all of the changes to be made. The area with the red box is where the image has been cut — the layer mask has been applied to that area (which is invisible in the preview but will be in the finished version). See the following section for info on using that tool and other image-manipulation tools.
The 8-bit grayscale pixels of a digital image are not just colors: They represent the finest degree of detail possible. For this reason, pixels are an excellent basis for manipulating an image.
Gathering the Tools
Photoshop has the tools for all of the image-manipulation chores you can imagine:
Selection tools: You can use a selection tool to select specific pixels in an image, group them, or even move them around. The Selection Brush is most likely to be used for moving the pixels you select, but it has many options. The Brush tool lets you apply color or paint over a specific area to color in that space or change its existing color.
You can create selections with the Magic Wand or the Free Selection tool. The Free Selection tool creates a selection that can be added or subtracted from another selected area. You can get the best results with this tool by beginning with a rough selection and then making small refinements.
Brushes: These tools can be used to apply color, change the color of an existing image, or create adjustments such as levels and brightness/contrast. You can also add layer masks to the selected area to make the adjustments. A brush is the easiest way to make small changes to an image. By the way, on the Brush tool, your options include the Brush Settings panel (where you make the type of brush you need and the size and strength of the brush).
Filters: You can use any of the filters in Photoshop to alter an image. These filter effects include the Color Replacement filter, which allows you to modify an image’s color; the Curves filter, which lets you change the tone, contrast, and brightness of an image; and the Camera Raw and Exposure filters, which offer a
Photoshop 2020 (version 21) Crack+ Free [Latest] 2022
Most users edit images using a Wacom tablet or similar to draw directly on the software and paint directly on the canvas. Some photographers use alternative programs like Affinity Photo.
In this article, we will explore the essential tools and key features of Photoshop Elements and why it is useful in photography.
How to use Photoshop Elements
Photoshop Elements uses a similar user interface as Photoshop. You will find a canvas with a similar set of tools to draw. Unlike normal Photoshop, many tools use a brush instead of a pen. For example, the brush tools can be used to select areas and paint in, and the pen tool can be used to draw straight lines and curves. The canvas is often larger than the photo you are editing and is often a background that is hidden.
To start Photoshop Elements, click the “File” tab and select “Open”.
After your photo has been loaded, you can open the edit tools by clicking the icons below the viewport.
You can use the tools in the middle of the screen to navigate the image using the mouse. You can use the tools on the right to interact with the image using the keyboard.
If you are using a Wacom tablet, then you need to adjust your Wacom settings first. Check that your tablet is connected properly (you will need to have a cable to connect it) and the software must be running. Then, go to Preferences > Wacom and adjust your screen resolution and monitor orientation.
If you do not have a Wacom tablet, you need to manually set up the mouse, keyboard and drawing tools. To do so, open the preferences by clicking on the “CS6” icon and select “General”. In the “Mouse” tab, adjust the resolution and display orientation. Then, find the “Pen” tool and click on the box near “Features”. Use the arrows to move the starting point of the pen and adjust its resolution. The same settings can be found in the “Specials” tab under the “Pen” tool.
The brush tools are controlled by using the brush tool. To start painting, click on the brush at the bottom of the interface and start painting. To select a color, click on the color box next to the brush. In the middle of the
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Q:
I have installed MBPro photo manager, is it possible to save the collection in my android using MBPro or is it incompatible?
My app is to collect all the photos taken by my iphone. i have installed MBPro photo manager and i want to save all the albums in MBPro to my android. is it possible? or should i use third party photo management apps?
A:
MBPro is not a photo app, it is a photo manager.
Use
to get the data from the photos in the app
[Surgical treatment of gastroduodenal reflux in ulcer patients with reflux gastritis].
Our study included 16 patients (ten men and six women) who had undergone surgical treatment for recurrent ulcer disease and reflux gastritis. In three patients the disease manifested itself clinically and endoscopically as perforative gastroduodenal ulcer. In the remaining thirteen patients reflux gastritis was diagnosed in the absence of any gastric or duodenal ulcer or other digestive tract pathology. In the early postoperative period in all the patients we found good and stable results. The mean postoperative follow-up time was 3.6 years. Despite the satisfactory postoperative outcome with exception of two patients, five of whom had necessary hospitalization in the early postoperative period, reflux gastritis persisted in the same degree in our patients as it was observed preoperatively. This observation, as well as the long-term good outcome of gastroduodenal ulcer surgery, should be an argument for the application of surgical reflux treatment in patients with complicated ulcer disease and reflux gastritis in the absence of marked endoscopic changes.1984–85 Milton Keynes Dons season
The 1984–85 season was Milton Keynes Dons’ third season in the Football League.
Out of contract players
Competitions
League
Results
Transfers
In
Total spending: ~£29,000
Out
Total income: ~£72,000
References
Category:Milton Keynes Dons F.C. seasons
Milton Keynes DonsQ:
How to multiply all the values in a list?
I have a list of values
What’s New in the?
The father of a transgender teen that committed suicide after his community shot and killed her says he has a message for the community.
“Just because we lose a child to something doesn’t make us any less, we are still the same family. And I believe the truth will prevail and we are all in this together,” said Wade Creason.
On Friday morning, members of the Middletown community gathered together at the corner of Empire Street and Buck Creek Road in Middletown to honor the memory of Jenner Nash.
Jenner Nash, 17, was among a group of teenagers who got into a fatal car crash last month.
“They’re going through emotional turmoil at this time in life and it was as if they were a whole different race, a whole different country…. They’re being harassed,” he said.
Community members said they want to rebuild, but often the message they hear is, ‘you’re not welcome, you’re like an outcast because you’re not like us.’
“That’s no way to live. They should be free to live, they should be free to walk around, they should be free to be who they choose to be. They want to make a difference in people’s lives, and as much as they can, they want to make a difference in other people’s lives,” said Creason.
The community hopes one day transgender teens will be seen as their true selves.Many of the frameworks in python that are popular, ie. django, flask, and others do have code that is not open source. I don’t see much reason to have this information publically disclosed and I see many benefits to keeping it secret.
I think that all of the challenges that the neural network have to overcome is very interesting and mostly we don’t know how they work. I would love to get access to that code to see how it works.
Open source is a good thing. Open source is what makes the internet work. This is also extremely important for open source libraries like Keras that use wrappers of neural networks. The matrices that are used to solve a neural network are not distributed, many are not stored on the cpu, and many of them are randomly generated. This is to preserve the users privacy.Pogo (Kim So Hyun album)
Pogo (stylized as PGLOW) is
System Requirements For Photoshop 2020 (version 21):
AMD | Intel
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RAM: 8 GB
Hard disk space: 2 GB
Graphics card: NVIDIA GeForce GTX 970 (supported at 1920×1080)
DirectX: Version 11
Operating System:
Microsoft Windows 7, 8, 8.1 and 10
Mac OSX 10.6 or higher
Linux Ubuntu 11.04+
Steam Version:
Photoshop 2021 (Version 22.4) Crack+ [Mac/Win] [March-2022]
Basic Photoshop: File Types, Layers, and Adjustments
Adobe Photoshop files are actually tagged and tagged, meaning that the file uses a tag table that contains names and tags for each individual layer.
The three main parts of Photoshop are the Image, Layer, and Adjustments. Each part offers users different tools to manipulate their digital image.
Image:
The image is your photo or other source. You can crop, rotate, flip, distort, resize, sharpen, and sharpen; make adjustments like Levels, Curves, and Black and White; create layers, and use a selection tool to target areas of the picture.
Layer:
Your layers are places where colors, images, and text are placed on the screen. Layers are managed through the Layers panel. Each layer is an independent image file; in other words, you can place images and text anywhere in the document. You can also combine two separate layers into one, either by using the Layer Masks feature or through a Layer Composition mode.
Users can choose from the available adjustment tools, such as Levels, Curves, Hue/Saturation, Blacks and Whites, Brightness/Contrast, and more. These tools operate by adjusting the overall image’s appearance, often in a range of small increments (per channel) that enables a user to fine-tune their image.
It can take a few months to get used to using Photoshop. It is a huge help to practice a few times using the Training Utility or Adobe Photoshop CS6 Welcome Guide. It will teach you everything you need to know to use Photoshop.
Basic Photoshop Tools
Layers:
Layers are a complex and powerful feature, but new users often have difficulty understanding them and using them. There are six layers in a Photoshop document. You have a background layer, which can be blank. Then you have a layer on top of that, called a regular layer. Layers are divided into groups of layers, called layersets. A layer can have multiple, so you can group layers together or make a selection that only has the part of a layer that you want to see. It’s helpful to practice placing layers on the canvas with the Layers Panel. If you remove a layer from your canvas, you can always get it back by clicking Layers > Flatten Image.
Layer Composition:
When you merge two or more layers into a
By the way, Photoshop elements and Elements are available for Windows, Mac and Chromebook.
Let’s get started.
How to install Elements 2020?
More tips
Windows
What platform are you using?
“Windows 7, 8.1, 10”
“Windows 7, 8.1, 10” What version of Elements are you using?
“Elements 5.3.3”
“Elements 5.3.3” Do you already have Photoshop?
“No”
Mac
What platform are you using?
“MacOS Mojave 10.14”
“MacOS Mojave 10.14” What version of Elements are you using?
“Elements 5.3.3”
“Elements 5.3.3” Do you already have Photoshop?
“No”
Linux
What platform are you using?
“Ubuntu 16.04”
“Ubuntu 16.04” What version of Elements are you using?
“Elements 5.3.3”
“Elements 5.3.3” Do you already have Photoshop?
“No”
Smartphone
What platform are you using?
“Android”
“Android” What version of Elements are you using?
“Elements 5.3.3”
“Elements 5.3.3” Do you already have Photoshop?
“No”
Elements, Photoshop and CC
Version CC (desktop)
Version CC (mobile)
Version CC, for Android
How many and which smartphone do you have?
“2 Android phones”
“2 Android phones” What smartphone do you use for photography?
“Galaxy”
“Galaxy” What smartphone do you use for graphic design?
“Galaxy”
“Galaxy”
Can you tell us a bit about yourself?
Yes, it’s my first post.
Yes, it’s my first post. How long have you been using Photoshop?
“3 years”
“3 years” What has Photoshop done for you?
“It is the best piece of software for graphic designers and photographers.”
“It is
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Photoshop 2021 (Version 22.4) Crack+ Incl Product Key
Americans are not well-acquainted with the U.S. government’s role in sponsoring organized religion. Under the Constitution, church–state separation is a prominent principle. But who really knows?
Attorney General Jeff Sessions’ recent confirmation hearings before the Senate Judiciary Committee gave a glimpse of what Americans can be taught about this touchy topic. U.S. Sen. Al Franken of Minnesota attempted to find out:
QUESTION: Do you think that the United States Government ought to be in the business of promoting, advancing or supporting one religion over another?
SESSIONS: I have not had the occasion to spend a lot of time thinking about that issue.
The questioner justifiably wondered whether the federal government was promoting any religion. But as the Supreme Court has now established in its 2018 decision on the Texas “bathroom bill,” the U.S. government generally must promote same-sex marriage (the other side of the constitutional coin). The latest Executive Order, issued in May 2018, makes clear that it is the federal government’s policy that states and localities must comply with the terms of the U.S. Supreme Court’s Obergefell v. Hodges decision. The EO also specifies that transgender rights are to be protected.
But what about the free exercise of religion? The Department of Justice has issued guidance — first in 2011, and then in a more detailed 2016 regulation — laying out the government’s policy. In both instances, Sessions confirmed his belief that the government had a positive duty to protect religious liberty. As he said in his 1999 speech to a religious freedom task force: “Protecting people’s religious liberties is a critical cornerstone of a free and just society.”
So that is one view. The other, which Sessions did not address, is that religious liberty is primarily an individual right — the state’s duty is to protect the vulnerable and ensure that no one is unjustly victimized.
Americans have a healthy skepticism about government endorsement of religion, sometimes to the point that it overreaches. But we have a more than healthy suspicion of religious groups proselytizing or engaging in activities that run counter to the traditions of their religion.
In any event, it is fair to ask whether the U.S. government should be promoting any religion.
Franken quoted an exchange between Sessions and Joe Biden, when the latter was chairman of the Senate
What’s New In?
Imaging for coronary artery disease: techniques and interpretation.
Coronary imaging is an important, noninvasive diagnostic modality for patients with suspected coronary artery disease. Coronary artery calcium (CAC), coronary artery calcification, and coronary artery stenosis can be imaged quantitatively or qualitatively in the heart and coronary artery vasculature. The presence or absence of these findings, along with the hemodynamically relevant information they provide, has a large bearing on the management of patients with chest pain and the risk stratification of asymptomatic subjects. In the diagnosis of coronary artery disease, coronary calcium is more useful than coronary artery stenosis in symptomatic patients, whereas coronary stenosis is more important than calcium in asymptomatic patients. However, both imaging modalities perform poorly in the diagnosis of coronary artery disease in patients with increased risk for coronary artery disease (eg, diabetes) and normal coronary arteries. Functional myocardial perfusion imaging, myocardial ischemia detection, and viability imaging may also be performed to help assess myocardial viability and ischemia. The screening of asymptomatic subjects is controversial because of the availability of risk stratification tools that are more accurate than screening.C. The activation of Akt phosphorylation at Ser473 by Ang II observed in the present study is different from previous studies, which reported the phosphorylation of Akt at Thr308 in response to Ang II in rat hearts $[@CR5]$, mesenteric resistance arteries $[@CR24]$ and renal cortical collecting duct epithelial cells $[@CR25]$. Therefore, the Akt phosphorylation at Thr308 is not a general phenomenon during Ang II-induced vasoconstriction.
Because Akt regulates diverse cellular functions, especially cell proliferation and survival $[@CR26]–[@CR28]$, Akt-overexpressing cells have been employed as tools to elucidate the physiological role of Akt. For example, Akt was cloned into adenovirus vectors and infected into H-RAS-transformed rat mesenteric arterial smooth muscle cells $[@CR29]$. Akt-overexpressing cells showed an enhanced proliferation rate compared with the parental cell line $[@CR29]$. Using this model, we found that Akt activation induced by Ang II was strongly inhibited by the expression of the catalytically inactive form of PI3K
System Requirements For Photoshop 2021 (Version 22.4):
Discord Server:
You can download the client here ( ) and join the server here ( )
To join the Discord server, click on the join button at the bottom of the above link, and then enter the password ‘EggZingA’.
This is a text based RPG, currently in a demo version. Once the demo is complete we will
Note
We’ll refer to a Photoshop file as _PSD_ in this book. A Photoshop file is actually called a _Photoshop Document_, but it’s known as the _PSD_ file in more casual conversation.
# Materials You’ll Need
This book is organized around a series of individual Photoshop lessons. Each lesson uses a specific set of materials, as described in the checklist that follows. In addition, you’ll need an appropriate copy of Photoshop and some way to view the web pages you make.
Your copy of Photoshop should be a _Copy Protection_ version, which we describe in Appendix A. A _Copy Protection_ Photoshop document requires that you make one or more _Copy_ and _Modify_ operations. While you can use the older Pro versions for this work, since there’s no longer a security wall between modules, we recommend you use the more recent Version CC software. You
Adobe Photoshop 2022 Incl Product Key 2022
What does it take to be a good Photoshop user? Is it just practice? Or, is it really knowing the ins and outs of the program?
For most people, the answer is both. And this guide will help you be a better Photoshop user in no time.
So grab a cup of coffee, sit back and enjoy this Photoshop tutorial guide…
1. Use Keyboard Shortcuts
To speed up your editing, you should always use keyboard shortcuts. If you’re using a keyboard with a number pad, you’ll need to use number shortcuts to switch between tools or selections, so learning those is a must.
For example, when working with layers, you would hold down the “W” button to bring up the layers palette, and then scroll to the desired layer and press the “E” button to bring up the layer controls. You can also use “shift” to select multiple layers.
Press “E” + “W” to select a range of content. Press “E” + “SHIFT” to select a rectangle.
You can also use “E” + “L” to load content from a file or a URL.
If you’re new to Photoshop, and you’re going to use a lot of shortcuts, or if you’re looking for the easiest keyboard shortcuts, you might want to follow this guide.
It includes the popular shortcuts that are common to Photoshop and many other programs.
2. Get Certified
Photoshop is a commercial tool, so you’ll need to pay for your membership.
But that doesn’t mean you can’t become a certified user in Photoshop.
Get a free trial of Photoshop if you haven’t already, and then use the tutorials on the website to see if the program is right for you.
If you think you’re stuck, this certification is a great place to start.
It includes a free trial of Photoshop and a self-paced learning system with video tutorials.
The program is divided into four sections:
General editing & workflow
Design with AI
Design with artboards
Design with sketching & illustration
Each section is designed to teach you the techniques and tools for each section, and if you can’t get past the
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I have a custom styled notification, that looks like this:
I want to display that notification on the status bar. I found that I can achieve this using the following code:
But my problem is that the second line of code does not show the notification on the status bar of my phone. I do not get any errors. I have Android 4.0.4 installed on my phone. What is wrong with this?
A:
Android doesn’t support your notification. Only the system supports. You can create a custom Layout and just use that.
When we went to the U.S. in the late 70’s, when I was
a teenager I worked in a sweatshop.
It was very hard work, but I needed the money and
it’s always good to learn a trade.
So, I thought I’d fit in, and when the supervisor came in I bowed to him and greeted him as if he was my master.
He was very pleased. I guess he thought he was a master.
He agreed with me that I should be paid a little more than the others.
I was proud of my doing that, but he was angry because
he’d been having problems with the bosses.
I thought that was the end of it.
But after about 3 or 4 weeks, he came in again, because of the
hard work of the others, and he started to complain that I was very bad-tempered.
He said he must have been having problems with the bosses, because I was the first to resort to violence.
I was very proud of that. I thought I was doing a good thing.
But he said he’d been having trouble with the others.
He said, “I can’t even manage to punish you.”
He was very displeased with me, because in his words I was “an extremely bad employee,
and I’d have to look for another place, because I can’t work with such a person.”
As he left, the other workers came in and said, “You know, that supervisor has
What’s New In?
Waves (Lydia Loveless album)
Waves is the debut solo album by American country music artist Lydia Loveless. It was released independently by her own label, Telluride Records, on April 30, 2013. The album includes the singles “Waves”, “One of Us” and “Nice Place”. The album was released for digital download and streaming on April 30, 2013 and for physical release on June 3, 2013.
Critical reception
Critical reception to Waves was positive, and Allmusic gave it four out of five stars, and American Songwriter magazine gave it four-and-a-half out of five stars, calling it, “a ringing, honest, sincere, and well-crafted debut CD that has the potential to be her biggest and best record yet.”
Track listing
Charts
Album
Singles
References
Category:2013 debut albums
Category:Lydia Loveless albums
Category:Self-released albums
Category:Albums produced by Frank Liddell
Category:Albums produced by Scott HendricksWe’ve all been there. Perhaps the worst part of spring break is the prospect of returning to a job that’s mandatory — or, worse, much like spring break in the paper-pushing sense of the term.
We’ve all been there. But the question is, does anyone know how to get out?
Several job search gurus have found the key to springing yourself out of a difficult job — you need to make it easy on yourself.
“The reason people don’t always give up is because they think of it as a trade: If I’m going to get up at 7 a.m., I have to get up at 7 a.m., and so I go through this mental gymnastics to convince myself that it’s a fair trade — it’s not fair for me to get up at 7 a.m.”
It’s hard to want to get up at a reasonable hour if you’ve just been working 24 hours a day (not that we’re judging) and the prospect of getting up at a reasonable hour may sound like a cruel and unusual punishment. But setting a new bar in your life is a great way to kick your job search into high gear.
Making it easy on yourself
Searching for a
System Requirements For Adobe Photoshop 2022:
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Processor: Intel Core i3-2100 or AMD equivalent
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Adobe Photoshop 2022 (Version 23.1) Crack Activation
* Adobe Photoshop, www.adobe.com/products/photoshop.html. * iPhoto/Aperture: “ * The Art of Digital Photography by Jeffrey D. Keyes (Wiley Publishing, 2008) * Using Photoshop CS2 for Photographers by Randy Morse, Randy Hamilton and Randy V. Hite (McGraw-Hill Osborne Media, 2008) * Digital Photo Workshop by David J. Simms (A & C Black, 2009) * Photoshop Elements, www.adobe.com/products/photoshop.html. * Adobe Photoshop Elements 6 Classroom: Essential Skills, www.pe6.com/section/reference. * Photoshop Elements 6 Fundamental, www.pe6.com/section/fundamental. * Photoshop Elements 6: Advanced Techniques, www.pe6.com/section/advanced. * Photoshop Elements 6: Elements in Practice, www.pe6.com/section/practice. * Adobe Photoshop Elements, www.adobe.com/products/photoshop.html. * Tips for Photoshop Elements, “.
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Do I need to use Photoshop? Adobe Photoshop is an industry standard. It is the go to tool for professionals in most fields. Professionals prefer to use Photoshop because they expect a better result with its industry-leading features. However, if you need to edit only simple photos or posters, you don’t need Photoshop. Photoshop is for people who love to work with Photoshop. Photoshop Elements is for people who don’t want to master the advanced features of Photoshop. It is an elegant software that gets the job done. Who should use Photoshop? Everyone can use Photoshop. It offers editing and creation capabilities to almost everyone. Anyone with a computer and a desire to do some photo editing can learn to use Photoshop. Photoshop Elements is for people who want to do simple photo editing but are not interested in mastering Photoshop features. If you do not need to edit a lot of pictures, Photoshop Elements is the right software for you. What do I need to use Photoshop? Adobe Photoshop is a graphics editing software. Photoshop is a Windows-only software. Photoshop is fully compatible with 64-bit Windows versions. Photoshop is a very intuitive software. It is suitable for users of any age. However, to use Photoshop effectively, you need to use a monitor that has a resolution of 2K (7680 x 4320 pixels) or 3K (8490 x 5446 pixels), to get a good experience with the program. Photoshop Elements is a graphics editing software. It does not require a high resolution monitor to view the image. Adobe Photoshop requires Adobe Creative Cloud. Photoshop Elements does not require it. Why do I need to use Photoshop? Photoshop is the most powerful image editing software and photo editing software out there. Photoshop has the industry-leading features. Photoshop is the go to software for all types of graphics professionals. Adobe Photoshop is an image editing software that has everything an image editor needs. It is used by photographers, graphic designers, and web designers to edit their images. Photoshop has the features to create professional-quality graphics. If you need to edit an image, Photoshop is your software. Why do I need to use Photoshop Elements? Photoshop Elements is an alternative to Photoshop. Photoshop Elements is a powerful tool for image editing. It is suitable for people who only want to edit and create images. Photoshop Elements is a good start for people who want to use Photoshop but do not a681f4349e
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A. Hardware Requirements: You will need a PC with Windows 10, 8.1, 8, 7, Vista, or XP Service Pack 3 or later, or a Mac with OS X Mountain Lion or later. You will also need Internet Explorer 10 or later. You will need to have a new, free, or paid version of Adobe Flash Player 11 or later installed on your computer. You will also need a camera that captures images in the JPEG format. You must have at least 1.5 GB of available hard disk space.
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Photoshop, CC – Learn to Work With it by Zooming in on the Process with This Expert Guide for Creative Pros
Photoshop, CC—Learn to Work With it by Zooming in on the Process with This Expert Guide for Creative Pros
Zooming in on the process of image editing by Photoshop can be difficult to begin with, since the program’s interface is designed for the entire image to be seen at once. The “eye icon” at the top right of the window’s toolbar enables users to see multiple layers stacked on top of one another.
The layers are the various stages of an image editing project, where every aspect of the editing can be seen simultaneously.
How to Work with Transparency in Photoshop
How to Work with Transparency in Photoshop
There are two layers on the top of the Layers Panel, named “Background” and “Layer 1.” They are the two layers that make up an image. Photoshop has the capability to make the layers transparent, allowing users to see through the image’s background. When an image editing project is started, Photoshop prompts the user to make a new layer. While a background layer is made visible, the background image covers the top layer.
The top layer is named “Layers 1.” The file shows the user’s current layer names.
The Image Layers panel enables users to switch between the layers of an image that has been opened in the program. A user can switch between layers by clicking on the images at the top of the panel.
The Layers Panel can be accessed through the Panel menu or the Window menu. A user can also access the Layers panel by highlighting the top image in the Layers Panel and pressing Control (Ctrl) and F on the keyboard.
Users can add a new layer to an image through the image’s Image Layers panel by clicking on the Layer icon. It is located at the bottom left of the Layers Panel.
To rename the image’s top layer, users can click on Layer 1. By double clicking on the top layer, users can change the name of the layer.
The Layers Panel Stacks Layers Using Transparency
The Layers Panel Stacks Layers Using Transparency
There are two layers in Photoshop for a file. The top layer, “Layer 1,” is the original image. The bottom layer, “Layer 2,” is what is being worked on at the moment.
The user can toggle between the
Adobe Cracked Photoshop With Keygen Elements vs Photoshop
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Adobe Photoshop Elements vs Photoshop CS2
Adobe Photoshop Elements vs Photoshop CS1
The digital imaging software Photoshop has become an integral part of the professional practice of photography and design. Photoshop is a paid software and has many powerful features, the best of which is the ability to edit images and replace content with another image.
When doing an image editing project, you have to start with editing the background of the image. Most often the image is editing in a black background. However, this may not be the case for all projects. Therefore, you will find an accurate list of all the features in all versions of Photoshop.
Photoshop CS4 features
Editing software Adobe Photoshop Elements is available for free for a single user and not required to be licensed for a commercial work. Photoshop Elements is the beginner-level version of Photoshop and it is available for Mac or Windows.
Open, save, and work with a file
The first thing you will want to do when editing images in Photoshop Elements is opening and saving the image.
Adobe Photoshop Elements has a familiar interface, with many tools, options, and controls. The interface of Photoshop Elements is similar to both versions of Photoshop, CS and CC. The Elements version is not a fully-featured version of Photoshop, but it has the basic features you are looking for.
Are Photoshop Elements images resized?
You will not be able to save JPEG files that are greater than 8 megapixels in Photoshop Elements. Otherwise, the file will have a resized or distorted quality. If you want to save high-resolution images with unlimited quality, you will have to go to Photoshop.
Photoshop vs Photoshop Elements
Image sizing
You can use up to 8 megapixels in Photoshop Elements, while saving an image that is greater than 8 megapixels will resize the file.
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The Dodge & Burn tool, which has three different modes: Burn, Dodge, and Burn+Dodge, can be used to correct gray-scale or color levels in images.
The Gradient tool is one of the most powerful tools in Photoshop. It can be used to change the colors in a specific area of an image and create new colors.
The Magic Wand Tool allows you to select a specific area by clicking on it.
The Pen tool in Photoshop is used to create new shapes, paths, text, and shapes to define borders and backgrounds.
The Paint Bucket tool is used to select all the pixels, which have a specific color, in an image.
Effects
Photoshop comes with a lot of effects, which allow you to edit images in various ways.
The Dodge & Burn tool, which has three different modes: Burn, Dodge, and Burn+Dodge, can be used to correct gray-scale or color levels in images.
The Gradient tool is one of the most powerful tools in Photoshop. It can be used to change the colors in a specific area of an image and create new colors.
The Gradient Tool can be found along the top menu bar and can be used to change the colors in a specific area of an image.
The Camera Raw filter works on the camera raw files and can be used to open RAW files in Photoshop. It can also enhance the colors and contrast and allow you to edit the image without the need to convert it into a JPEG file.
The Adjustment Layers allow you to change the brightness, contrast, and saturation of any part of the image.
The Levels tool allows you to adjust the brightness, contrast, and saturation of the selected area.
The Spacing tool helps you adjust the brightness, contrast, and saturation of the entire image.
The Pattern Selection tool is used to create patterns in an image.
The Animation tool can be used to create a new image within the layer, which can then be used to animate either text, shapes, or an image.
The Type tool allows you to create text in a selected area and create a font in a new area.
The Perspective tool allows you to move the entire image by a certain amount.
The Smudge tool can be used to erase parts of the image.
The Blur tool can be used to blur a specific area.
The Gaussian Blur tool can be used to blur a specific area of an image.
The Emboss tool can be used to
What’s New in the?
# 深度学习
# 简介
# 本文档
* [起初的研究](#起初的研究)
* [The Horse in King Lear](#TheHorseInKingLear)
* [视觉猫](#视觉猫)
* [卷积神经网络](#卷积神经网络)
* [深度学习与深度学习框架(slims)](#深度学习与深度学习框架slims)
* [线性图](#线性图)
* [聚类(cluster)](#聚类cluster)
* [直线增强](#直线增强)
* [持续学习](#持续学习)
* [联合学习(共聚算)](#联合学习共聚算)
* [双向感知](#双向感知)
* [
System Requirements For Photoshop:
Minimum:
OS: Microsoft Windows XP (32 bit)
Processor: Intel(R) Pentium(R) CPU 3.06GHz or AMD Athlon(R) CPU 3000+
Memory: 2 GB RAM
Recommended:
OS: Microsoft Windows 7 64-bit
Processor: Intel(R) Core(TM) i3 or AMD Phenom(R) II X4 945
Memory: 4 GB RAM
Photoshop With Product Key For Windows
One of the most common use of Photoshop is to crop the image you have taken so that the image meets the specifications of the given context. Cropping is the process of removing a portion of the image to create a much more visually pleasing composition. Cropping means removing pieces of the edges of the photograph. When you’re finished, you end up with an image that is much tighter and easier to look at.
In this chapter, you find out how to do the following:
Manipulate an image: Cropping, layering, using layer effects, and working with masks
Create and modify layers
Apply a filter
Detect and correct perspective
Resize and crop images
Work with templates
Reduce red-eye
Rotate and mirror images
The software you’re about to use in this chapter — Adobe Photoshop Elements — is a relatively inexpensive image-editing program. Adobe describes Photoshop Elements as “Photoshop for Creatives.” While it offers the same tools as the full version of Photoshop, it does not offer nearly as many features. It lacks the layers and advanced color and mask features of the full version. (For more on layers, check out Chapter 8.)
You can use Photoshop Elements for the following tasks:
Creating and editing raster images
Printing on a desktop printer
Creating and editing GIF images and web graphics
Cropping and resizing images
Laying down images
Using the basic tools of Photoshop
Using the basic tools of Photoshop to create graphics
For a beginner, you can turn to Photoshop Elements to work quickly on these types of images. If you’re experienced at working with Photoshop, you can save yourself the time and use Photoshop’s advanced features, such as using layers and masks, adjusting filter settings, and so on.
One of the nice things about Photoshop Elements is that it has a photo-editing free trial. If you’re having trouble mastering the program, you can come to it knowing that it won’t cost you a penny unless you decide that you want to use the full version.
Manipulating Images
Once you understand the basics of manipulating an image, you’re on your way to making your own manipulations. One of the first things you can do with a photograph is change its perspective. Photoshop Elements has a feature called Perspective Transformation (also called Transform
Photoshop Crack Free Latest
How do you start a project? The first step is to determine what you want to do and how to accomplish the goal. An image editing tool allows you to work quickly and produce high-quality images with various tools to modify images.
Photoshop Free Download allows you to change many aspects of an image, from color, saturation and contrast to special effects, perspective, adding and cropping elements in your images. Photoshop makes it easy to create a variety of effects and processes from portrait and landscape to creative and clip art styles.
Photoshop is the most widely used photo-editing tool. With this product, you can create professional-quality images. You can enhance the images for printing, create and save cropped images.
Pros:
It is a very powerful tool for those who want to save time or are a beginner. It does not require any additional software for running.
It does not require a large amount of disk space to work.
Cons:
Unable to edit RAW files.
The documentation is quite extensive.
Created by Adobe in 2007, Adobe Photoshop Elements is an alternative to Photoshop. It is a software for all the needs of those interested in photo editing. It is designed to make it easy for both professional photographers and casual users.
Adobe Photoshop Elements provides features for photographers and anyone who edits images. The software is for organizing and modifying digital photos.
Let’s look at some features of this software.
Word, PDF and HTML editing tools
A file manager tool that allows you to organize and manage your photographs.
Integrated photo editor tool that allows you to edit images with two tools:
Segmentation, which lets you use tools such as Paintbrush, Blur and Healing Brush
and Brush, which lets you use tools such as Paintbrush, Blur and Healing Brush Channels, which create layers for compositing
Image/photo sharing tool that allows you to share your images and organized collections
Optimized software that allows you to manipulate each photo by aspect ratio with the Scale tool
Good quality results even when you have limited equipment
Easy to use toolbar for quick adjustments
The software is designed to make it easy to share images on social networks and websites.
Pros:
It is a quick tool to edit, crop, add text and resize images.
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Photoshop Free
}
public enum _GraphicState
{
None = 0,
Filled = 1,
Intersecting = 2,
AlphaChannel = 5,
Scaled = 10,
Offset = 11,
Crop = 12,
Unknown = 13
}
public struct _DPI
{
public IntPtr ptr;
public _DPI()
{
}
public _DPI(IntPtr ptr)
{
this.ptr = ptr;
}
What’s New In Photoshop?
Q:
IndexOutOfBoundsException in Arrays.sort(int[])
I am trying to sort an int array in Java, that works fine, but when the array is very big, i get IndexOutOfBoundsException: Index out of bounds. I haven’t figure out, where it is coming from.
Arrays.sort(array);
This is my exception:
Exception in thread “main” java.lang.IndexOutOfBoundsException: Index: 32927, Size: 32928
at java.util.ArrayList.rangeCheck(ArrayList.java:635)
at java.util.ArrayList.get(ArrayList.java:411)
at com.comp.java.ex.Arrays.sort(Arrays.java:40)
at com.comp.java.ex.Arrays.sort(Arrays.java:19)
at com.comp.java.Game.main(Game.java:21)
It is maybe something very stupid, but I don’t see it!
A:
Basically you have a LinkedList rather than an ArrayList: Arrays.sort(array) uses the linkedlist methods, whereas Arrays.sort(int[]) uses the native array methods.
The best way to solve the problem is to convert the LinkedList into an ArrayList:
int[] array = (int[]) new ArrayList(Arrays.asList(array)).toArray(new int[0]);
But you can also solve the problem without changing your List implementation:
int[] array = Arrays.copyOf(array, array.length);
Arrays.sort(array);
Note that Arrays.sort(int[]) is not the best choice.
Q:
Create a graph with two vertices linked by multiple edges
This is just an example of what I am looking to do. I have an actual graph I am trying to create that I cannot quite figure out.
The structure of this is the following:
I want to create a graph with those vertices where the first two vertices will be joined by 6 edges (and with the vertices marked in red), the last vertex will be linked to two other vertices (vertex 5) with two edges (and marked
System Requirements For Photoshop:
Windows 10, Windows 8, Windows 8.1, or Windows 7
Mac OS X 10.10 or later
iOS or Android device
Internet Explorer 11
For iOS, Android devices
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A coauthor of this book was once called into the office by a client who claimed his arch nemesis in the marketing world had “Photoshopped” the image from a magazine. Unfortunately, the person in question had merely recolored the photo from a real country landscape to that of a painted model; only the people and places had been changed, and this was not a trademark infringement. I don’t know why anyone would lie like this, but I certainly won’t tell you what the lie was all about.
Do you know of any pictures that a small child can look at and draw? Of course, he knows that when he creates an image it must be placed on a background of some kind, such as a color. He also knows that the image must have a certain type of form, such as the image of a dog or a house. Although the child does all of these things, he does not understand how to add layers to an image to produce a better effect.
In the same way, a Photoshop novice can create a series of layers and make the image look like it’s been done professionally. However, if you don’t know how to use a layer-based image editor, you may never understand the countless ways to work with your images and see what you may have missed.
This chapter offers advice on the many possible features you can use in Photoshop to enhance your work.
Working with Layers
In Photoshop, everything you see in the window is part of a layer. Each layer has a number. Figure 1-1 shows the number of a layer at the bottom of the screen. The top layer is Layer 1, the one that’s shaded.
Figure 1-1: Layers are numbered at the bottom of the screen and appear at the top.
Anyone can add a layer. You can create one by using the New Layer option. You can also create a new layer by pressing Shift+Ctrl+N (Shift+⌘-N) or creating a new document. If you place an image on a new layer, you can easily make changes to it and then save that as a separate file.
You can click the dotted box at the top of the Layers palette, as shown in Figure 1-2, to show a preview of the active layer. You can use the pixel ruler to measure the size of an image on a selected layer.
Figure 1-2: You can make changes to a selected layer and preview
Photoshop is a professional and popular image editing software program from Adobe. It’s different from the other image editors because it’s got different features like Effects, Curves and Adjustments. Plus, you can edit your images and create high-quality images in much more depth than any other editors.
Adobe Photoshop is a very popular, professional-quality image editing and illustration software application from Adobe. It is a good alternative to Photoshop and is much less costly than Photoshop. Adobe Photoshop comes in three versions: Creative Suite, Photoshop Creative Cloud and Photoshop Elements.
Some of the features of Photoshop are rotoscoping, image retouching, photo correction, gradients, shapes, 3D objects, and typography and web design. Photoshop’s tools help create a layered document which can be easily manipulated, modified, and organized by layers and selections. Layers are defined in the Photoshop layers palette, and the Photoshop workspace is laid out like a kitchen table with virtual space on both sides of the desktop. Photoshop is a professional tool. It has many features and it is less expensive than Photoshop Elements. In addition, the newest versions of Photoshop come with additional features and tools.
Image Editing Photoshop Tutorials in the 21st Century
Nowadays, we need Photoshop to edit images because it enables us to transform ordinary photos into magical ones by various means. We can use image effects and presets, add different artistic styles, do photo manipulations, replace images and many more. Photoshop is a very complex software, but one thing that can’t be disputed is its great compatibility, or it is easier to use than other photo editing applications. We can find this on the internet.
The big advantage of Photoshop is that we can create anything we want in it, we’re only limited by our creativity. However, we can do a lot of things like changing the size, cropping, lighting, sharpening, and also adding effects to our photos or photographs to make them look amazing. The features of Photoshop are so rich that anyone can do anything. We also have tutorials that will help us learn how to use Photoshop in the easiest way possible.
Photoshop is a fabulous photo editing tool which enables you to manipulate photos in a very broad range and have a lot of freedom. This software provides tools and features to help you edit and create images easily and creatively. We have some of the best tutorials here. The basic skills of Photoshop are the basics of photo editing
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Q:
Would producing and capturing a commercial extra-terrestrial signal influence physics?
Now that we are able to build radio-telescopes that we consider are sensitive enough to capture a distant extra-solar planet, it’s a little more plausible that at some point in the future we will get a radio signal from an extra-solar planet (assuming that planets are massive enough to actually produce radio waves).
Assuming that we could actually capture the radio waves, and that it would really be a separate object, where the planet itself isn’t at risk of colliding with us, what would we gain from observing that radio signal?
Obviously we would be able to work out the distance to the object, and calculate the density of the planet, but that’s not much more than we would if we didn’t have the radio waves.
Is there any reason to observe the radio wave if we don’t plan to do anything with it?
A:
Assuming that we could actually capture the radio waves, and that it would really be a separate object, where the planet itself isn’t at risk of colliding with us, what would we gain from observing that radio wave?
We would gain information about the planet. In particular, we could see if the planet was in the habitable zone of its parent star (assuming it has a star that isn’t a red dwarf of the type that is more likely to produce a planet that gets tidally locked to the star), or whether it was too large to be habitable. Even for earth-like planets in the habitable zone, it can be useful to look at how much water they have, and whether they are covered in water or are covered in land, and whether the planets radiates any thermal infrared, and so on.
The planet’s mass is unlikely to be useful in any way; we could perhaps use the planet’s mass to rule out certain types of stars as possible host stars (e.g. if the planet has a mass similar to Jupiter’s, then that’s evidence against a Sun-like star hosting it, as stars like the Sun don’t have Jupiter-mass planets; if the planet has a mass similar to Earth’s, then it’s probably too large to be habitable). More likely, it will just give an upper limit on the mass. The planet’s chemical composition will be interesting though, and it will be interesting to see how much the planet deviates from what we think is the bulk composition of the
2.3.2 –
System Requirements For Adobe Photoshop CS6:
*Recommended*
Memory: 512MB
Hard Disk: 2GB
*CD/DVD drive*
Game Auto Save Not supported
*Windows OS*
Windows 7 or above (Please note that Windows Vista and earlier are not supported)
*Strong internet connection*
*Minimal system requirements*
Process
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Note
Adjusting the size of the document can be helpful if you’re working with a particular size print or scanner. To modify the size of the document, use the Constrain and Size options on the Size panel of the Preferences dialog box (Figure 6-1).
5. **5. Do any necessary cropping or scaling**.
Photoshop offers many tools for cropping images, including the Rectangle, Marquee, and Hand tools. You can crop an image to a particular size from the Rectangle or Hand tools, or you can use the Marquee tool to create a free-form selection for more accurate cropping (Figure 6-3 on page 206).
As you drag the cursor, the corner of the selection box remains stationary, while the rest of the selection box moves with the cursor.
To scale images, use the zoom tool (the + icon in the upper-left corner) or, in the Layers palette, drag the percentage bar up and down to adjust the size of the image.
6. **6. Choose an image adjustment tool**.
The various tools that Adobe offers in Photoshop include:
Figure 6-1. Click on the down arrow in the bottom-right corner of the Layers palette to open a palette of available
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Here’s the guide, with 575+ definitions:
1. JPEG:
A device that converts RGB to YUV 4:2:0, RGB to YCbCr 4:2:0 and RGB to YCbCr 4:4:4
I’m trying to teach you Photoshop and I will have to start with the basic stuff.
2. Chroma Key:
A device that removes the background in an image.
3. CBR (Compressed Bitrate):
An encoding standard used in digital communication to decrease the amount of data that needs to be transmitted. It was originally developed by the International Telegraph Union (ITU) as Recommendation T.81 for bit rate reduction.
4. ECC (Error Control Code):
This is the error correction method for the CP1252 encoding used in Windows.
5. Topaz:
A software company based in Houston, Texas, USA, who developed topaz, one of the best app ever.
Topaz is designed to help you create the designs of the future. Our technology is a progressive approach to the design and production of music-focused and video-focused components and modules. We’ve been producing fantastic quality products since 2004 (and counting!). Today Topaz is an affordable and powerful software and hardware system. Now you can take your music projects anywhere. When this music studio was developed in a garage by three friends, no one thought that they would still be around, and that Topaz has become so successful. Now we’re putting all our energy into expanding our team and creating new products in the next decade.
6. Weirdness:
This is the error that is thrown when we give some input to some weird value.
7. Validation Panel:
A panel used to display critical errors and warnings when a value is received and saved.
8. Blur:
The effect that produces softer edges in an image. When the Fuzziness is set to 0, nothing is blurred.
9. Color Checker:
A color chart used to show the actual color of any object/scene that is viewed/captured.
10. Sharpness:
How much contrast an image has, it is used to enhance images.
11. Anti-aliasing:
A method used to blur the
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The ENU mutagenesis program at CMCF/EMBL since 2005.
The European Nucleotide Archive (ENA) is a central database for nucleotide sequences and meta-data of all genomic and transcriptomic sequences, created and managed by EMBL-EBI. The ENU mutagenesis program at CMCF/EMBL selects spontaneously mutagenized mouse ES cells for high-throughput screens using state-of-the-art biotechnologies. Mutant animals are housed at specialised animal facilities and are subsequently bred to establish mutant lines in C57Bl6/J and/or 129/SvEv genetic backgrounds and maintained as recombinant inbred populations (RDPs). The international ENU disease mouse network (EDMN) provides information on new mouse models for human monogenic and complex diseases. The ENU mutagenesis program at CMCF/EMBL shows the importance of mutagenesis screenings for improving the knowledge of human diseases as demonstrated by the large number of successful publications of about 250. This commentary gives a short overview of the ENU mutagenesis program and some of its achievements since 2005.[Chylothorax: a retrospective analysis of 22 cases].
Chylothorax is a rare condition characterized by an abnormal accumulation of lymph within the pleural space. In the last decade there has been growing awareness and wide use of thoracic lymphangiography; therefore, the frequency and etiologies of chylothorax have been documented for the first time. We report 22 cases of chylothorax, observed in our centre in the last 15 years. The etiology of most cases was malignant diseases, especially breast cancer (n = 10), followed by lymphomas (n = 5), and bronchial carcinoids (n = 3). Thoracic lymphangiography was performed in 16 patients, showing that in the majority of cases, the etiologic cause of chylothorax was lymphangiectasia, consistent with aneurysmal dilatation of efferent lymphatic vessels. Interestingly, chylothorax was responsible for two thirds of the severe complications reported in this series (e.g. mediastinitis and parapneumothorax). Less than 5% of patients with chylothorax were associated with thyroid lympho-angiosarcoma. Breast cancer is the most common form of chylothorax and, consequently, patients usually present
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Q:
Using property of javascript array in perl script – returns Cannot get property ‘length’ of undefined
I am trying to use a javascript array in perl script. But it is giving error as
Cannot get property ‘length’ of undefined
I am doing following script.
use strict;
use warnings;
use feature’say’;
use DBI;
use CGI;
my $q = new CGI; my$dbh = DBI->connect(‘DBI:mysql:database=qa’,’qa’,’qa’);
my $sth =$dbh->prepare(‘SELECT COUNT(*) FROM qa’);
$sth->execute; my$count = $sth->fetchrow_array; my$total = 0;
my @arr = (‘dev’,’qa’,’review’);
foreach my $location (@arr){$total=$total+$count;
}
print “total db count is $total”; Here I am trying to get database total count and count for respective locations. For example: total db count for dev is 11, for review is 20 and for qa is 8. A: The following works: use strict; use warnings; use feature’say’; use DBI; use CGI; my$q = new CGI;
my $dbh = DBI->connect(‘DBI:mysql:database=qa’,’qa’,’qa’); my$sth = $dbh->prepare(‘SELECT COUNT(*) FROM qa’);$sth->execute;
my $count =$sth->fetchrow_array;
my $total = 0; my @arr = (‘dev’,’qa’,’review’); foreach my$location (@arr){
$total=$total+$count->[0]; } print “total db count is$total
“;
print “dev count is “, $count->[0],” “; print “qa count is “,$count->[1],”
“;
print “review count is “, $count->[2],” “; [5]int8 Pad_cgo_0 [6]byte } type BpfZbufHeader struct { System Requirements: OS: Windows 10 / 8.1 / 8 / 7 / Vista Processor: Intel Core i5-4590S / AMD FX-8350 Memory: 4 GB RAM Graphics: NVIDIA GTX 970 DirectX: Version 11 Network: Broadband Internet connection Hard Drive: 50 GB available space Sound: DirectX compatible sound card (stereo) Keyboard: Microsoft Sculpt Display: 1024×768 resolution Additional Notes: Must use the latest version of the game’s launcher. Adobe Photoshop CC Keygen For (LifeTime) [32|64bit] [April-2022] 🔔 Adobe Photoshop CC Activation Code For PC [April-2022] * Download the software from the Adobe web site and see if it’s right for you. # **Episode 72** **Drawing with the Pen and Touch Interface:** * Learn the basics of using the Photoshop pen tool. * Learn to draw using the pen in combination with the Draw and Pencil tools. * Save art and drawings in Illustrator and Photoshop. # **What You Will Learn** The last 10 years of software development have seen the demise of Windows as the operating system for digital artists. With the introduction of the iPad and Windows 8, its future as the primary platform for all digital artists has become as uncertain as a Microsoft stock. This is not a rant, by the way, but an opportunity for you to see how software development has changed over the last decade. Although software such as Photoshop is incompatible with the iPad and other smartphones, you will learn how to create your image manipulation using Photoshop’s pen tool and drawing abilities. You will also learn to save your image as an SVG file in Illustrator, which you can then import into Photoshop if you want to make additional edits. We will also dig into some of the familiar default and custom brush settings. # **Demystifying the Pen Tool** The pen tool in Photoshop has become one of the most popular new tools in the last few years. It’s now super-easy to use because the interface is touch-based, unlike earlier versions that required a digital stylus to be used. The pen tool itself is composed of a number of tools at the top of the toolbox. You can find the zoom tool, the Eraser tool, and a Convert tool. If you don’t see this toolbox, just right-click on the layer that contains the image and choose Layer→New→Pencil Strokes ( ). Let’s learn how to use this tool. **Figure 1.1** : The new Photoshop pen tool The pen tool (and most other tools in Photoshop) operates by grabbing the pixels that make up the selected area. This is why the tool behaves differently depending on which tool has been selected. For example, if you click the Eraser tool, you are actually erasing a path or path collection. This is because the path tool acts like a brush, choosing pixels and moving them around on the canvas. The Pen tool simply draws on the canvas. Photoshop provides several options for drawing along Adobe Photoshop CC Keygen For (LifeTime) [Latest] This article will show you how to edit photos, create graphics from scratch and create pixel art in Elements 11. With this guide you will learn how to: Create a logo, banner or symbol in a few minutes Make your own pixel art in Photoshop Elements How to add a watermark to your photos Create a custom Instagram profile background for any type of phone Add a cartoon to your screenshots Increase the resolution of your photos Choose the best photos for your social media profiles Generate JPG, PNG and GIF images from one single image How to use filters for professional photos How to create a web design from scratch The file size of your website matters a lot, so you will get tips on how to reduce your website’s size How to migrate to a new computer How to remove unwanted items and keep only the best from your images How to work with RAW and ProPhoto How to use the Free Transform tool to turn your photos into art How to use the Smart Filter tool to make your images look brighter How to use the Clone tool to get rid of unwanted objects How to use the Content-Aware tool to replace undesirable objects How to split a portrait into two How to use the Sepia effect How to make your existing photos look like high resolution photos How to use the Linked Adjustment tool to tweak your existing photos How to improve the look of your photos with the Curves tool How to use the Gaussian Blur filter to blur your photos How to create a new photo How to remove unwanted objects from a photo How to control the shape of your images How to apply a high dynamic range (HDR) effect to your photos How to add a vignette effect to your photos How to add a mosaic of photos to a single photo How to add professional effects to your photos How to control the brightness and contrast of your photos How to control the saturation of your photos How to reduce the file size of your photos How to remove dust and scratches from your photos How to convert JPG to JPEG How to add a vintage feel to your photos How to crop your photos to find the perfect shape How to choose the right type of images for your social media profiles a681f4349e Adobe Photoshop CC [Win/Mac] In July 1945, three days after the end of World War II, two Soviet soldiers arrived at the outskirts of Batumi, on the Black Sea, to deal with a large group of German POWs. The new arrivals ordered the bewildered men into pens, some of them with only a tattered blanket over their shoulders, and told them they were leaving for Germany. They marched them through the gates, then reversed course and returned a short time later with tanks, machine guns and half-track trucks. The men were led to a railway station and sent back to Germany, never to return to their families. Or so they believed. Little did they know that their families were already there awaiting them. When the soldiers arrived at the station, they were lined up with the other men and ordered to proceed to the platform. They were led to a vehicle, and told to get in. But this was no ordinary prison transport. The troops were packed in like sardines, sitting with their feet touching the floor. They were ordered to look straight ahead, and when the doors were slammed shut, there was no turning back. “It was a suffocating wave of sound, shouts, human screams, people crying, groaning, and the smell of excrement,” Berta Orlowska, whose mother was a German prisoner of war, recalls. Five days later, the train arrived in the West German city of Siegen. The men were led into a stifling, windowless room, and told to eat their first meal in five days. A man asked why they had been ordered to stay in the truck. A guard told him, “If you want to go back to the Soviet Union, you will get another opportunity.” They had been led to believe they would be going home. Many of the men were still bewildered. Some of them were suspicious about being sent away. One told his wife, “Now I am either going to get out here, or be deported to Siberia or the north.” When the train arrived, their worst fears were confirmed: They weren’t going back to the Soviet Union. It was Aug. 15, 1945. They had been taken to a transit camp, and were ordered to report to Camp 28, a place for officers and non-commissioned officers, where they were told they would be kept until What’s New In? Previous Article Next Article The Deptford Two The world’s most notorious asylum escapees, Harry and June ‘Jugger’ Nelmes, were admitted to Deptford in December 1851, aged 19 and 18 respectively. They were described by the Board of Visitors as ‘such a dissolute couple’ and an ‘unfortunate couple’. Harry, born in 1896, was the son of John Nelmes, a master mariner who became a policeman and was transferred to the custody of the ‘Prison Division’ of London Police in 1845. Harry had nine siblings, one of whom was the well-known professor of medicine and author of the paper ‘A Plea for the Prevention of Premature Birth’. Harry’s father died in 1852 and his mother, Elizabeth, died in 1853, leaving Harry at the mercy of foster parents. He was placed first with a family in Limehouse and later with an immigrant family in Lambeth in 1859. Then, in 1864, he enlisted in the 17th Lancers, a regiment affiliated with the Caledonian-Scot Regiment. His brigade was in South Africa and part of the famous Light Division. His service in South Africa was described as ‘of the greatest consequence’. He became a ‘Captain of the 17th Lancers’ and was part of the force which liberated the city of Mafeking. By all accounts, he did not behave badly while in South Africa but he was never awarded the Victoria Cross, which he asked for in 1881. He was released from service in 1873 and on his return to Deptford and later London, Harry Nelmes joined the staff of the Metropolitan Police as a Constable. However, he was discharged in 1878 and again joined the Police in 1885. As a constable, he was seconded to Scotland Yard and was posted at Lewes, Sussex. In October 1888, he was granted a transfer to Colchester Police. He was at Colchester when the Nelmes’ were admitted to Deptford. Meanwhile, his brother June (born 1851) was living in a lodging house run by a Mr Booth in Shoreditch, East London. On 12 June 1875, he was placed in Wandsworth Old Lodge for boys by order of the Board of Visitors, due to his violent nature. Henry and June were admitted at the System Requirements For Adobe Photoshop CC: Minimum: OS: Windows 10 (64 bit, version 1903 or higher) Processor: Dual-core 2.4 GHz or faster Intel Core i5-4590 or AMD Ryzen 5 2600 or better Memory: 8GB RAM (or higher if using 4K textures) Graphics: NVIDIA GeForce GTX 660 or AMD Radeon HD 7750 or better Disk: 6GB available space Recommended: Processor: Dual-core 2.8 Adobe Photoshop CC 2018 Crack + Activation Code Download Download Setup + Crack ··· DOWNLOAD (Mirror #1) Download Setup + Crack ··· DOWNLOAD (Mirror #1) Adobe Photoshop CC 2018 Crack+ Free Download [Win/Mac] Magic Wand The tool that enables you to select all the areas of the image that are the same color is the Magic Wand. It finds areas that are either the same color or are similar by virtue of the fact that they have similar shades of similar colors. It’s useful in several ways. For one, you can use it to crop and resize images, or add and remove backgrounds, backgrounds and borders, and text and other graphical elements, including logos and other images. You can easily combine the selections of multiple images into one by using a group feature called Merge to HDR or by clipping the image into a new file and putting it in a page or document of its own, turning it into a layered image. You can also use it to highlight a circular area of your choice. Adobe Photoshop CC 2018 For Windows (Final 2022) How do I open Photoshop Elements? Go to Settings > General > Applications. You should see two entries: Photoshop Elements and Adobe Lightroom. Select Photoshop Elements. Find the file you want to open in Photoshop Elements, and select it. You can also download Adobe Photoshop Elements here: System requirements It works on Windows XP/Vista/7/8/10 32-bit and 64-bit editions, including 32-bit and 64-bit versions of Windows 10. Read also: What are the best photo editing apps for Windows? Adobe Photoshop Elements 2017 14.0.0.1351 It’s possible to use Photoshop Elements 2017 on other platforms (Mac, Linux, etc.), but you can’t update from the Web version directly to the desktop version. To update, you need to download and install Elements separately. Here is an official review of Photoshop Elements, including tips and tricks for using the program. Also, be sure to subscribe to our newsletter to get the latest updates, including new features and special discounts (such as 30% off Adobe Photoshop Elements 2020). Getting started with Photoshop Elements Adobe Photoshop Elements 2017 is a version of the software available for both Windows and Mac. It’s simple to use and user-friendly. You’ll have to familiarize yourself with the basics of the program. In this guide, we’ll cover the most essential topics, such as importing and exporting images and videos. Also, there are guides on how to create graphics and edit photos. See: Importing images and videos One of the most basic features in Photoshop Elements is the ability to import images from other sources (other photo editors, digital cameras, etc.). Also, you can export to other image formats, such as TIFF, JPEG and GIF, and video formats (MPEG, QuickTime, AVI). You can use three different ways to import images: Drag and drop, browse by location or by path. The latter allows you to choose the folder in which you’d like to store your photos. If you want to import a photo from the Internet, you’ll need to go to the File menu, select Import from the Internet, and select the type of file you’d like to import (eg. JPG, TIFF, etc.) Importing images from a681f4349e Adobe Photoshop CC 2018 City of Hillsboro issues ‘Spiritual Emergency’ alert September 11, 2009 By By Rick Bowmer, AP HILLSBORO, Ore. (AP) — Authorities in the central Oregon city of Hillsboro are warning people to be on the lookout for a man who has sent bogus text messages saying he is planning to sneak into homes and kill a person to “bring back to life” his dead daughter. The Oregonian reports that the Hillsboro Police Department on Friday urged residents to stay alert for Andrew Robert McGregor, who also goes by the names of Danny LaCoush and Danny Young. McGregor has threatened to kill a person at each of the homes where he has received the phone messages, police said. Authorities warned that whoever receives the text messages “must contact their local law enforcement immediately.” McGregor’s 13-year-old daughter died in 2006 and he asked that her spirit be revived in May. The police say it’s unclear what, if any, connection he has with Hillsboro. Copyright 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.One of the best ciders Pouring his cider into glass bottles for the first time, the Italian’s hand went straight to his lips, hesitated for a moment then drew back, just as it had at his home in Slovenia. Dewar, an old family friend, was in the shop and offered a tasteless little sample glass. But Florian’s eyes filled with tears. “It’s wonderful,” he said. “I’ve only been drinking cider for about a year.” And he hasn’t looked back. At home in Italy, where he is deputy editor of the Federalia Industrialia newspaper, he’s the only one in his family, apart from his mother, who drinks it. In Slovenia, he describes himself as a “slovene who drinks cider”, someone who wouldn’t dream of buying supermarket ciders. But he has begun to crave them again and wants to learn to drink them straight from the bottle. “Slovenia is a poor country,” he said. “We’re not used to drinking strong liquids. We prefer to drink light beverages such as beer, beer and beer.” But Florian, who works for the British consulate in Ljubljana, has changed that and introduced What’s New in the Adobe Photoshop CC 2018? Who is on Sale Mascot for the U.S. 2010-2011 Athletics Men’s Basketball Championships Information Before the 2010-2011 Southeastern Conference men’s basketball season began, each member institution’s athletic department will have a chance to select a university mascot for the 2011 tournament. Schools will be allowed to participate in the sale only once. All bids must be submitted by the time the first round of bidding closes on Tuesday, November 3 at 6:00 p.m. ET. School mascot bidding order 1. College of Charleston The Cougars wear purple and gold, and are a member of the Sun Belt Conference. Before the 2004-2005 season, Charleston changed their mascot’s name to the Cougars. 2. Duke The Blue Devils are the all-time leader in Division I NCAA basketball championships, winning 10 national titles since the 1955-1956 season. The Duke also won back-to-back titles in the 2006-2007 and 2007-2008 seasons. 3. Florida The Gators will be part of the Southeastern Conference in the 2011-2012 season. Florida’s mascot is Geaux Geaux Gators. 4. Indiana Indiana’s mascot is Zellie, a custom-designed dog breed. 5. Kentucky The Wildcats will compete in the 2011-2012 season as members of the Southeastern Conference. Their mascot is Wildcat #55. 6. LSU The Tigers’ official mascot is Judd. 7. Memphis The Tigers will be moving from Conference USA to the Southeastern Conference in the 2011-2012 season. Their mascot is Black Bears. 8. Mississippi State The Bulldogs will be competing in the Southeastern Conference in the 2011-2012 season. Their mascot is Rebel. 9. NC State The Wolfpack is the official mascot of North Carolina State University. 10. Ohio State The Buckeyes will be part of the Big Ten Conference in the 2011-2012 season. 11. Tennessee The mascot for the Vols is Commodore. 12. Vanderbilt The Commodores and Vandy are brothers in the Tennessee Athletic Association. The Commodores wear navy blue and gold, while the Vandy wears light green and System Requirements: Renderer: Windows: Windows 8.1 and Windows 7 Mac OS X (10.10.5 and later) Linux (Ubuntu 14.04 and later) Memory: 8 GB RAM or higher Mac OS X: Linux: Graphics: 2GB RAM or higher i5-6500, i5-6500, i5-6200, i5 Photoshop 2022 Download Download Setup + Crack · DOWNLOAD Download Setup + Crack · DOWNLOAD Photoshop 2022 Crack + License Code & Keygen For PC If you intend to create artwork or graphics for print or for Web use, a production-grade application such as Adobe InDesign (in Chapter 14) would be a better choice than Photoshop. Versioning File History Photoshop allows for versioning, which is not a unique feature — it’s common to version your work in almost any image program. Just the fact that you have the ability to go back in time creates an invaluable option to help track any changes you’ve made to an image. To locate and use File History, follow these steps: 1. Open an image in Photoshop and press CTRL+Z (Windows) or COMMAND+Z (Mac OS). 2. If you see the Image\ History Panel (refer to Figure 5-5), click the History drop-down menu to open it and choose History Settings. The History Panel is divided into work areas in the right of your screen. The first is a work in progress area. The second area holds changes you’ve made to the image since you last saved. The third area holds the current or most recent image (just after you saved it), and the fourth holds images from three versions back. The sixth area holds images that you haven’t created an image from yet. 3. Choose the area (1, 2, 3, 4, or 6) you want to view and click the Show button (the arrow with a circle in the lower-right corner) to display that area. 4. You may find it useful to define areas to view the files that you want. Click the down-arrow button at the right end of the top-left area of the History panel to open the area menu (refer to Figure 5-5). From this menu, you can define the times that you want to track and the number of versions. For example, if you save several different files throughout the day, you may wish to track all of them. Or you may want to track only the most current image at any given time and track the prior ones as versions, making it easy to go back to previous work. You can also change the amount of time to track, from one version back to an arbitrary amount of versions back. 5. Also use the time option to select one or more days at which you want to track versions of the image. Click the radio button to the right of the time options to choose the days that you want to track. The days in the drop Photoshop 2022 Crack Download PC/Windows [Latest-2022] You can read our review of Photoshop Elements 2020 here. Adobe Photoshop is a commercial advanced photo editor. It can be used as a graphics editor, a web graphics editor, or an image editor. It is the most popular graphics editor and has taken over the market from Adobe Illustrator and other software such as ImageReady. It is available on a number of platforms including Mac OS, Windows and Linux. Photoshop is a different program from Adobe Photoshop Elements which is an alternative to Photoshop. The difference is that Elements is free to download and use on Mac, Windows and Linux computers. Adobe Photoshop CS6 is available for Mac, Windows and Linux. Adobe Photoshop is a professional program that offers most of the features you can expect in a professional graphics program. You can choose which version of Photoshop you require and it will download the program for you. Downloading a trial version of Photoshop If you are trying to download a free trial version of Photoshop you will not be able to do this directly from their website. There is no direct link from the Adobe website that will take you to the free trial version. You will need to search the internet for a download site. Most often you will see only Photoshop versions that have been specifically designed for Photoshop teachers. In most cases, this is not the version you want as it will not come with the features you need for your own images. You can get a trial version of Photoshop by searching the web for the name Photoshop and the word trial. Then install the program into a folder on your computer. If you want to try the free version you can install it as a trial version but you cannot use all the tools and features that you can use with a paid version. Using your free trial version of Photoshop The first thing you need to do when using the free trial version of Photoshop is to set the clock in the tool bar to match the time you are using. Many Windows users set the clock to their local time but with the free trial you need to use the “Local” setting if you are using the US version of Photoshop. Set the clock in the same way in the file menu. Now you can open an image in your free trial version to edit it. The image will open in Photoshop using the “Window” setting. You are able to make any changes you want to make to the image, such as adding elements a681f4349e Photoshop 2022 Crack+ [32|64bit] Q: Multiple url parameters to one GET request Spring MVC Controller I’m trying to make a GET request in Spring MVC that has multiple parameters. I’ve got a controller that looks like this: @RequestMapping(“/{name}/{order}”) public ModelAndView getCustomerDataByNameAndOrder(@PathVariable String name, @PathVariable int order, Model model, HttpServletResponse response) throws Exception { // do some stuff and return the response } I’m using resttemplate.getForObject() to do the actual GET request. I’m using this method because I want to be able to post to the same URL using two different parameters, but still use the same controllers. I can’t seem to find an example of something similar to what I’m doing. Is there a way to do this or do I have to write two different controllers? A: You can use @PathVariable like a regular @RequestParam: @RequestMapping(“/{name}/{order}”) public ModelAndView getCustomerDataByNameAndOrder(@PathVariable String name, @PathVariable int order, Model model, HttpServletResponse response) throws Exception { // do some stuff and return the response } Or if you want to use specific paths in your URL, you can create an annotation @PathVariable(value = “specificPath”) on your method. A: I am not sure I understand your question, but why don’t you do this @RequestMapping(“/customer/{name}/{order}”) public ModelAndView getCustomerDataByNameAndOrder(@PathVariable String name, @PathVariable int order, Model model, HttpServletResponse response) throws Exception { // do some stuff and return the response } Where customer is the name of the web service method A: You can use @RequestParam in spring mvc to define multiple request parameters What’s New In? , to keep his own self-respect, and to keep the respect of his teachers. 4. Some people think that they cannot be good in general; that they must never do anything they do not like. They must never do anything for money or to get what they want, or to avoid feeling uncomfortable. “I cannot do that,” they say. “I must do what I like, and I cannot like to steal or to do mean things to anybody.” Such people usually are never secure in their relations with other people. They do not know how to do things in a way that will make others happy. They think that others must want what they want, and in order to make others happy they must want the same things that they want. 5. Some people think that they are so important to themselves, and so nice and interesting, that if somebody else could have the pleasure of getting what they have, they should not want to have it. 6. Some people have a half-idea about honesty and fair play and justice, and love a game that is honest. But they forget that other people have different points of view. They do not think about what the other people will like and dislike, or about the way in which the game will affect other people. They make rules for themselves, and insist that they are right. Usually people who do this are not very selfish, and they have been told in their history class that they must be honest and fair. But they would not be so bad, even though they do not like to see it, if they could see that the reason they love a game of football is that it helps other people to enjoy themselves; if they could see that the reason they want to play a game of baseball is that it makes their fellow players happy. 7. Some people play games which are not honest, and some people play games that are not fair. Some people play games which are not fair to the other players, and make dishonest games and dishonest rules. Some people play games in which there is no rule at all, except to play the way you like. We have not found a word which says what we mean about playing games, or about playing games honestly, that we like. We are talking about System Requirements: Windows 7 and later Processor: 1.0 GHz Dual Core or higher Memory: 1 GB RAM Graphics: Shader Model 3.0 or higher DirectX: Version 9.0c or later Hard Drive Space: 20 GB NOTE: An internet connection is required to install the game. You can pick it up for$20 off its regular price of $24.99 here. Kombat on Kong is the latest game to hit the service, and is designed to be played with a copy of Dance Central Adobe Photoshop 2021 (Version 22.5) Activator Free Download [Updated] Adobe Photoshop 2021 (Version 22.5) With Serial Key Free (Final 2022) * Visit www.pixlr.com to view tutorials for beginners. * For more advanced users, check out Photoshop CS6: A Hands-On Guide from Robert Lewin for more in-depth information. # Working in Photoshop Photoshop is a powerful image-editing program that includes so much more than just photo retouching, as you can see in the following pages. As with any good software, you can use Photoshop for many types of image manipulations. For example, you can use it to blend images, create and work with composites, create web graphics, simulate design schemes for printed materials, and even learn how to use some of the program’s more creative features. This section helps you get up to speed with Photoshop. ## Choosing a Tool Photoshop has dozens of tools for image manipulation, including Retouch tool, Puppet Warp, Burn, and Filter. You can use all of these tools, but which one do you need? Selecting the right tool depends on the specific part of the image you’re editing. If you’re color correcting a photo or adding a collage element, you want the Retouch tool because it edits photos in one click and lets you control which colors change. If you’re creating a creative graphic or working on web graphics, you want the Filter tool because it provides a lot more control and allows you to change just about any aspect of the image that you want to change. Other tools are useful, but they can be overwhelming to use at first. For example, the Puppet Warp tool works well for special effects or morphing, but it can be confusing to use because it doesn’t allow you to see all of the results until you’ve completed the editing process. Although you can use many tools, they often work best when you use them together. For example, the Puppet Warp tool lets you alter the shape and position of images in Photoshop. You can apply the Warp filter to the original image or to a copy of the original. ## Getting to Know the Layers In Photoshop, an image consists of layers. A layer is a document that you can manipulate in any way you want. Layers can be masked, distorted, edited, or deleted. You can change the order of the layers, add more or delete them all, and even give the layers new names. When you’re working on multiple layers, you can create a new group of layers that act Adobe Photoshop 2021 (Version 22.5) Crack Torrent For Windows Image via Pixabay. Buying Photoshop Elements Elements 2018 is currently only available on the Mac platform. The previous version was discontinued in 2017. You can purchase the current version directly from the Adobe website. However, if you want to save money, many third party retailers offer special discounts and offer free shipping. They include: Photoshop Alternatives: Café Colour The first thing you need to do when you first open Elements is to rename the program. This will help you to keep tabs on all of your images and give you a better idea of which ones you need to work with and which one you should move onto next. Renaming Photoshop You are free to call the program whatever you like, but the standard name is Photoshop Elements. If you don’t rename your program, you will not be able to track your images and it will be much harder to find them. You can also add descriptive titles to each image to make your own specialized search function. Once you have renamed your program, you will see the most recent images you have uploaded and those you have added in recent months. If you are looking for a specific image, use the search function to find it. You can view the full size of any image by double-clicking on it. Elements also has specific image organizing features. For example, you can see all of the images where you have applied a specific filter or effect such as a blur or emboss. If you have too many images to keep track of easily in the Organizer, you can add more folders to help organize them into more manageable groupings. Photoshop Elements adds a number of view modes to help you organize your images based on their sizes. You can view all of your images at their original resolutions, thumbnail sizes, small sizes and large sizes. Elements also allows you to import images from other digital cameras and photo archives such as Flickr, Facebook, Instagram or Canvas+. This is useful when you have an abundance of images from a trip or vacation and you want to keep them all together. Adobe Elements Features: The Presets and Filter features are where you can do some of your most popular editing adjustments in Photoshop Elements. You will be able to adjust things like Sharpening, Smoothing, Exposure, Contrast, Gradient and HSL/Color Balance. Some of these features will need to be unlocked by accessing a681f4349e Adobe Photoshop 2021 (Version 22.5) Crack + # Previewing the multiple file backup In the Menu bar, choose File -> Store Backup -> Preview. On the next page, choose the images you wish to preview, and then select a viewing mode. What’s New in the? Dear Derivative Writer: We have a new name for you, and we are looking for your new home. We are proud to announce our new division, Enron Global Markets. The Global Markets Group, chaired by Mike McConnell (former CEO, Allied Chem, & current board member, Exelon), and co-chaired by Jeff McMahon, (Former COO, Chevron, & current board member, Phoenix Electric), consists of our Global Crude & Products, Global Coal, Global LPG, Weather and Insurance trading groups. We need your expertise and your talent. Mike McConnell Chairman & CEO Enron Global Markets 713-853-6428Get On Board Do you want to get to Washington and work with us as a paid staff person? Are you prepared to get involved? Are you ready to get on the bus and go where we’re going? If you have the desire, are willing to learn, are committed and willing to work with a group of dedicated people, then get on the bus and get to work. If you do not have these skills or do not have the desire to get to Washington, get on board anyway, just for the adventure, just for the experience, just to meet new people, make friends, just to see what it’s like and be a part of something big. And we’ll see you soon.In wireless communication systems, antennas are utilized to transmit and receive radio frequency (RF) signals. In some applications, multiple antennas are installed to achieve spatial diversity and/or a receive diversity gain. For example, in an 802.11a-based wireless network, such as a wireless local area network (WLAN), two antennas are used to receive RF signals. Each antenna includes a low noise amplifier (LNA) and an analog-to-digital converter (ADC). The two ADCs receive RF signals from the antennas and provide the received RF signals to an equal gain combiner (EQGC). The EQGC combines the received RF signals and provides the combined RF signal to a filter (e.g., a band pass filter) that extracts signals from a baseband. Referring to FIG. 1, a wireless communication system 100 includes a number of antennas 102a-d (i.e., 2 antennas in FIG. 1) to receive RF signals and a number System Requirements: Compatibility: Windows 7 (SP1), Vista, Windows Server 2003 R2 (SP1) RAM: 1GB Hard disk: minimum 1GB Processor: 1.8GHz Video: DirectX 9.0c Sound: DirectX 9.0c Input: Keyboard, mouse Network: Broadband Internet connection Software: Internet Explorer 9.0 In The Direct3D SDK, Direct3D 10.1 is supported, and in Direct3D 10.1a, Direct3D 11. Photoshop 2022 crack exe file Photoshop 2022 Crack + Download PC/Windows Advanced photographers and teachers use Photoshop in a highly sophisticated way to create specialized photo effects and image composites, edit photos and videos, enhance images, and create alternative visual styles. In fact, Photoshop is often used to produce artwork for magazines and publications. As with any tool, advanced Photoshop requires both time and dedication to master and will require some technical training on the part of the user. A New Way to See the World Photoshop is not only a tool for image editing but also an imaging tool. It has many interactive options, including the ability to transform images and interact with them. For example, you can place and manipulate text on images, add annotations and arrows to accompany text, and create frames. In addition to the traditional tools, Photoshop offers over 50 plug-ins and filters to enrich images. You can create special effects such as weather maps, create color effects, add stars and other effects, and use special tools such as the healing brush to restore images. Newer applications such as the video app, Capture One, can be used to record video that is then edited with Photoshop. Other tools include Smart Fix, which saves you time by identifying the problem area, replacing it with the original image, and allowing you to avoid the need to make any changes. Using the Scanner tool, you can even have a document scanned and automatically use it as a template. And if you select an object in an image and use the Move Tool, you can drag and drop it to a different spot in the image. Although you can set up and work with multiple images at once and can work on many different projects, Photoshop isn’t a stand-alone program. You have to access other programs and files to work on your projects. And though you can use your hard drive as a storage area, if your hard drive fills up, you can transfer images to a CD or DVD to work on them. The following sections take you through the most common ways to use Photoshop. Taking about layers A vital aspect to Photoshop is the use of layers. Photoshop enables you to work with groups of layers called Layers. You can manipulate a group of layers, adjust their characteristics, and then save the group as a layer. You can then do different kinds of editing to that group of layers. For example, you can add a new layer of a photo in a special viewing mode that converts the image to grayscale (transforms the image) and then use the paint bucket tool Photoshop 2022 Product Key Download 2022 And yet, if you don’t have a powerful computer, if you’re poor or just want to save money, Adobe Photoshop Elements can be your best friend. Let’s look at how to get started using Photoshop Elements Download and install Photoshop Elements Before starting Photoshop Elements, you need to download the software. You can download it here. When you run it for the first time, the program will ask you for a default installation folder. By default, this folder will be the one that is located at Adobe/Program Files/Adobe Photoshop Elements 12. Installation process 1. Import a photo Open Photoshop Elements. Click Create and drag the photo to the new canvas. 2. Adjust photo Adjust your photo using the following tools Crop: In this part, you can select several presets and move and resize your photo. On the left side of the screen, you’ll find a bar with several selections. Click on it to access the Crop area. Move and zoom the image with the handy handles. Using the History panel, you can go back to previous stages of a photo. Straighten: This tool allows you to automatically put your photo in focus. Adjust the ratio using sliders in order to detect the correct aspect. 3. Edit photo You can use most of the editing tools, filters and effects that are found in Adobe Photoshop. Make smart edits This is the most complex part of this editing tutorial. When you have a lot of work to do, selecting the right tools to use can be frustrating. In this case, we will work on a portrait of an old lady. You will see how to transform the photo using filters, adjust the contrast, and add a contour in the skin area. Let’s start! Adjust the contrast Click Enhance > Enhance, then adjust the levels. If you’re having trouble, you can use the HSL and LAB Color tools to adjust the entire image: Click on the small icon in the upper left corner to access this palette. The histogram shows you the distribution of your pixels. You should see a thin band corresponding to the white pixels (allocated area). The color wheel shows you the colors you can choose. By selecting different colors, you can change a681f4349e Photoshop 2022 Mechanistic investigation of naphthalene biodegradation in bacterial cultures using AP/MS analysis. For polycyclic aromatic hydrocarbon (PAH) bioremediation, the specific identities of the enzyme(s) responsible for naphthalene (NA) degradation have not been established. A wealth of information is available about the degradation mechanisms and corresponding enzymes involved in biodegradation of phenanthrene and anthracene and some PAHs containing one or more lateral groups. Of the enzymes identified as being involved in phenanthrene and anthracene biodegradation, only the dioxygenase naphthalene 1,2-dioxygenase (NahA) has been shown to catalyse the first step of naphthalene biodegradation. In this study, we analysed the substrate specificity and regulatory mechanisms of NahA in Pseudomonas putida F1. When expressed in Escherichia coli, NahA was found to catalyse the oxygenation of various exogenous aromatic compounds, including NA, methylnaphthalene, phenanthrene, anthracene and anthracene-9-methylene. Polycyclic aromatic hydrocarbon degradation products were purified and identified using combined liquid chromatography-mass spectrometry. The degradation products of naphthalene, phenanthrene, anthracene, and anthracene-9-methylene contained 1,2-dihydroxylated and/or 4-oxylated aromatic hydrocarbons. Docking analysis of NahA using different substrate analogues revealed that the biodegradation products resulted from a single and novel biodegradation mechanism. A conserved catalytic triad composed of His-168, Asp-456 and His-402 was found to interact with the lateral alkyl group of NA, and the hydroxyl group of 1,2-dihydroxylated compounds. The overall reaction mechanism was demonstrated to be the following: substrates were initially oxidized to substrates with a molecular weight of 106, which were then further oxidized to substrates with a molecular weight of 108. Finally, dioxygenation occurred in the lateral, cyclohexyl ring, resulting in the formation of a dioxygenated product with a molecular weight of 110.1. Field of the Invention The present invention relates generally to the field of soybean breeding. 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Sponsored by Inova, the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) and the Arthritis Foundation, the event provided more than 300 rheumatologists and scientists with an in-depth look at this condition that is affecting approximately 1 in 50 of the U.S. population. “This was a remarkable scientific meeting,” said the Center for Rheumatology and Connective Tissue Medicine, Dr. Smith. “This is a complex autoimmune condition that affects the body’s immune system, and there has not been a single treatment approved by the Food and Drug Administration for this condition. Fortunately, a small number of patients have responded positively to our treatment protocol.” In the United States, there are an estimated 300,000 people who suffer from ankylosing spondylitis, an autoimmune disease characterized by inflammation of the spine and a stiffening of the joints. 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When you save a Photoshop file, you have many options for choosing file format. Most of the common file types include the following: Adobe Photoshop (.PSD) file: The most common file type, this file is for advanced editing. It can contain multiple layers, perform advanced color-correction functions, and can be exported to other file formats. If you click File⇒Save As, you have several options from which to choose, including Photoshop file, Adobe Illustrator file, and so on. Photoshop file (.PSD) with images compressed in the JPEG format: A common file format, compressed JPEG is highly compressed so that it takes up less space in the disk. When you download pictures and files from the web, JPEG files are often used, so you usually can view them just fine in your image-editing software. Photoshop file (.PSD) with transparent and non-transparent images: A very rare file type, transparent and non-transparent images in the PSD file are converted to separate layers. 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Collages can be used on product images, wedding proposals, infographic projects, social media graphics, and more. In order to create them, you need to click on the new button at the bottom of the layer panel. Then add your desired images in the panel. You can also add texts and shapes using the text tool. 2. Create a new type of infographic layout You can create a new type of infographic layout by simply dragging the elements you need on to the timeline. You can then type all the text and images you need into your timeline. You can also create layers and arrange your elements as per your preference. 3. Reduce the size of an image This is one of the most important tasks for graphic designers. Photoshop allows you to reduce the size of a single image or a group of images by simply clicking the scissors icon. This will allow you to save a certain amount of space for your images. You can use this feature when you are designing slideshows, videos, or when you are making thumbnails. You can also use it to create smaller sized images or download them from the social media networks like Instagram and Facebook. How do you resize an image in Photoshop? Open the image you want to resize. Click on the photo icon. . Click on the image size menu. menu. Click on the aspect ratio menu. menu. Drag the handles. The aspect ratio menu is located in the menu bar of the image. You can change the size by dragging the handles. You can also adjust them manually by clicking and moving them. 4. Enlarge an image You can enlarge any image either by simply click on the crop tool or by dragging the handles. You can a681f4349e Adobe Photoshop 2021 (Version 22.4.1) PC/Windows 2022 [New] Sub menu Social Icons About DUBAI, United Arab Emirates (AP) — Iran’s president says it’s possible to reach a nuclear accord with the U.S. after years of hostility over the country’s disputed nuclear activities. President Hassan Rouhani offered hints at a potential easing of tensions, calling for a new day of mutual respect, according to the official IRNA news agency. Rouhani said Saturday after talks with visiting U.S. congressional delegation that the Islamic Republic was ready to return to international negotiations, according to his chief of staff, Esfandiar Rahim Mashaei. The U.S. and other Western nations suspect Iran’s nuclear program was aimed at building atomic weapons. Iran denies seeking the bomb, saying its peaceful nuclear program is meant to generate electricity and produce medical radioisotopes. The U.S. and the United Nations’ top nuclear watchdog have imposed a series of punitive measures against Iran, saying it has violated a nuclear deal with world powers and agreed to curb its nuclear activities in exchange for relief from sanctions. Rouhani has suggested the approach might not work, saying in a speech Thursday that the U.S. could not trust the Islamic Republic. He also has called on the West to back an Iranian-led initiative to ease tensions in the Middle East. Mashaei said Rouhani and President Barack Obama “underlined the need to make an effort to get out of the wall of hostility toward each other.” The U.S. delegation included Rep. Kay Granger, D-Texas, the chairwoman of the House of Representatives Appropriations subcommittee that funds the State Department. Negotiations over the nuclear deal are deadlocked because of disagreements over what inspections would entail. Granger said the U.S. was ready to resume talks, although White House spokesman Jay Carney said the sides needed to give time to resolve the impasse. “It’s possible to come back to the table,” Granger said. She called the Obama administration’s decision to send the letter stopping further talks a “tactic and not an overture” and said her main message to the Iranians was “this is the best time to come together.” Rouhani said the latest round of nuclear negotiations, which began last month, marked a “historic turning point What’s New In Adobe Photoshop 2021 (Version 22.4.1)? Q: How can I view the definition of a keyword/property in F#? I sometimes forget to prefix the properties that I use in F# with the access specifier (ie: x in C#), so I was wondering if there is a way to view the definition of a property in the Object Browser in Visual Studio. A: You can find information about a declared identifier using Alt-Q in Visual Studio, F12 in Visual Studio Code, or F12 in the MonoDevelop editor. That’s not quite as convenient as the actual definition in the code, but it often works out better than the Visual Studio Object Browser. Image caption By day, the wall is an abstract representation of a flat plane The image is a perfect representation of the artist’s idea – but in reality, what that wall has in store is much different. In every way, when viewed from one angle it is flat – but from another, it is pitched at a steep angle. If you walk across the south side, they end abruptly at a cliff, effectively forming a stairway at 45 degrees. And that means that, from high up in the sky, it looks as if someone has painted a flight of steps into a cliff-face. Unlike the image, with time the white paint on the wall will keep peeling away, leaving the dark brown sandstone below. This means that as the cliff recedes it will keep getting lower. It’s an installation that is part of an ongoing exhibition at Peplow, the National Trust’s gallery in Somerset. Sandstone cliff When we think of chalk and its cliffs we think of white cliffs on the south coast of England. But in the Cotswolds, a cluster of villages and towns that give a rough shape to the chalk formations that start to dominate the landscape as we head south from Birmingham, the cliffs are so far away as to be invisible to the naked eye. Paul Keates, whose gallery Peplow is hosting the exhibition, calls the new work looking into the abyss “a meditation on the topography of a flat plane”. The gallery sits on a vast stretch of land at the entrance to Saunton Sands, a private country estate. The cliff here faces a succession of isolated rocky points or bosses – coastal landforms that are the remnants of a former raised beach. At the surface of that particular area of System Requirements: System Requirements (Desktop): Windows XP or newer Mac OS X 10.7 or newer 64-bit Windows or Mac Minimum of: 1 GB RAM 4 GB of available hard drive space 800 x 600 screen resolution DirectX 8.0 compatible video card 7 days of internet connection Network connection Intel® Core™2 Duo processor or AMD Athlon™ 64 X2 Dual-Core processor with a minimum of 2 Photoshop CS4 Crack Keygen With Serial number Full Product Key (Final 2022) Photoshop CS4 Crack + Download For Windows [2022] In this guide, you’ll learn the basics of Photoshop, along with how to use the best features the program has to offer. Before you begin your Photoshop journey, keep in mind that while Photoshop is an extremely powerful tool, it is also has plenty of quirks. Practice and experimentation is the best way to master Photoshop. To ensure you stay up-to-date with the latest features, you should also take advantage of the Photoshop blogs and tutorials that can be found online. These bloggers will help you master the features Photoshop has to offer, so you can take the next step in your Photoshop career. What is Photoshop? The goal of Photoshop is to enable users to edit color images in a broad range of ways. Photoshop is designed to be a layer-based image editor, and offers many tools and features that enable users to manipulate layers and create composites. Photoshop is designed to be used in a multi-monitor environment, with one application window for image creation and another for editing. The new Adaptive Design application mode, which allows the program to dynamically swap between editing and creative modes, enables this multi-monitor workflow. Unlike many other programs, Photoshop also includes an image browser, organizing images by type, subject or folder. It also includes an image adjustments panel that provides easy-to-use adjustments to a specific image’s color or tonal range. Manipulate Colors to Create Amazing Images Using Photoshop’s photo editing features, you can make a Photoshop photographer’s life easier. If you’re an amateur photography professional, you can use Photoshop to get an edge over your competitors. It’s common for the top photographers in the industry to use Photoshop extensively. Reduce Red-Eye in Photos Red-eye is often caused by an auto-flash that is triggered when a person opens their eyes to take a photo. While many cameras have a red-eye reduction feature, this can also be fixed in Photoshop. It can be as simple as applying a dark red or orange color to the areas where the pupils are open, or it can be a much more complicated operation. Most of the Photoshop tutorials focus on an easy to implement red-eye reduction method. If you’re ever going to fix a photo of a person, it makes sense to learn how to reduce red-eye before you take it. Produce Amazing Looks Using Photoshop’s Image Adjustments While Photoshop isn’t a Photoshop basic, it’s no secret that the Photoshop CS4 Crack (Latest) The Elements features standard image editing tools, such as the Healing Brush, Spot Healing Brush, Color Replacement, and Smart Brush. There is a built-in application that allows for batch image compression. But since Elements lacks the professional quality that Photoshop does, images often need to be either saved as PDF files or exported to another image editor to further alter them. Part 1: The Photoshop Elements 12 Editor (PST, PSD, PSJ files) If you have an older version of Photoshop, you must upgrade to Photoshop Elements 12 to use the regular editing tools. Let’s see how you can open and create graphics in Photoshop Elements 12. Step 1: Log in to Photoshop Elements First, you must log into Photoshop Elements 12 from the beginning. When you first log in, you’ll be asked whether you want to continue where you left off. If so, click Continue. Otherwise, click Cancel to log out. (Note: If you have done your homework and understand that this is an old version of Photoshop, you should click Cancel.) Step 2: Click the empty bar on the left side of the Home screen, which is where you will find your menu and buttons. Step 3: Click the arrow icon to open the Media Library. Then select the Select tab and click OK. Step 4: When the Open dialog box appears, make sure you’ve selected a.png file that you want to open. Step 5: Click Open. Photoshop Elements opens the selected.png file. Step 6: Click the Windows logo at the top right of the screen, which should look like a circle with a small rectangle inside of it. Step 7: Click “Start.” Step 8: Click “More tools” to open the Start menu. Step 9: Click on “Options” to open the Options window. Step 10: Click “Preferences” in the left-hand side of the Options window. Step 11: Click “Display” to switch to the Display tab. Step 12: Click “Full screen” to allow the Settings window to appear. Then toggle the Full screen option to “on” to make it appear full screen. Step 13: Click “Save” to save changes, a681f4349e Photoshop CS4 Crack With License Key Free Download [32|64bit] [March-2022] -Borg1]. Granulocyte-Colony Stimulating Factor (G-CSF) expression is significantly increased in the amniotic fluid of pregnant women at term [@pone.0066270-Hollister1] and induced by uterine contractions [@pone.0066270-Nakagawa1], [@pone.0066270-Terazawa1] suggesting its involvement in labor initiation. Up-regulation of G-CSF in preterm labor is associated with increased CCL3 and CCL5 expression suggesting that G-CSF may play an important role in the initiation of labor [@pone.0066270-Hollister2]. However, up-regulation of G-CSF has also been found in pregnancies that go into preterm labor but do not progress to overt labor [@pone.0066270-Hollister1]. IL-6 is frequently increased in the amniotic fluid of women with preterm labor and spontaneous rupture of membranes [@pone.0066270-Tyrka1], [@pone.0066270-Orbegozo1], suggesting its involvement in pathophysiology of this condition. IL-6 is often associated with T-cell activation and proliferation and may be involved in the initiation of labor in part by stimulating the synthesis of prostaglandins [@pone.0066270-Garnovski1]–[@pone.0066270-Mastrocola1]. Further studies are needed to better understand the role of these cytokines in the pathogenesis of preterm birth. The role of inflammation and infection in the pathogenesis of preterm birth has become increasingly evident. Pro-inflammatory cytokines, anti-inflammatory cytokines, and acute phase proteins may all play a role in the initiation of labor [@pone.0066270-Farlik1]. These findings support the hypothesis of a locally mediated inflammatory response in the uterus [@pone.0066270-Boeck1], [@pone.0066270-Giuffrida1] and suggest that a local inflammatory component is an important cofactor in the process of labor induction. Our data further confirm the role of cytokines in preterm labor [@pone.0066270-Posey1], [@pone.0066270-Simpson1]–[@p What’s New in the? Q: parse a string and append it to a new object C# I am trying to generate an object using a string, but I am not receiving the object. Here is my code: static void Main(string[] args) { List list = new List(); myClass obj = new myClass(); string line = “….”; foreach (var x in line) { list.Add(new myClass { propertyA = x.PropertyA, propertyB = x.propertyB }); } } } public class myClass { public string PropertyA { get; set; } public string propertyB { get; set; } } I want to create an object and a string at the same time and this is my output: A: public class myClass { public string PropertyA { get; set; } public string propertyB { get; set; } } static void Main(string[] args) { List list = new List(); myClass obj = new myClass(); string line = “….”; foreach (var x in line.Split(‘ ‘)) { list.Add(new myClass() { PropertyA = x.PropertyA, propertyB = x.propertyB }); } } then this is the final object public class myClass { public string PropertyA { get; set; } public string propertyB { get; set; } } Historical perspectives of contemporary university experiences. 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Finding an Estimate of Skill Level You need to factor the skill level of the technician who is going to photograph your products and prepare your photographs for the press. If you have a photographer friend who does this kind of work for you, be sure to describe your products and their appearance, as well as what kind of image you want. Photographers come in all sizes, styles, and expertise levels. For example, you may have a photographer friend who always produces great images for a particular type of product, and she does this professionally as a side business. After you talk to her, you realize that she doesn’t need to charge a great deal to photograph your product. You may want to choose a photographer on a freelance basis for the job, or you may want to have a photofinisher do the job. Either way, you must know what you’re getting yourself into so that you’re not disappointed or losing money, and the photo-related work that you do together is not a one-sided arrangement. Seeing the work that’s been done before Before you choose a photographer, you should see what’s been done to other products. You should look at the other products that have been photographed and see what they look like. You should also look at the quality of the photographs. You want the pictures to be sharp enough to see details on the product, but not so sharp that you can’t find something in the picture. When you give a photographer a project to work on, use it as a way to gauge how she does her work. Photographers often disagree on how and what to photograph, and the photographer may not be sensitive to how you prefer the image. Being critical of how the photographer works on the work can be a way to be helpful. You can do the best you can to give the photographer a project and then do any editing yourself after the fact. It’s best if you and the photographer work from the same starting point because of the time differences involved. An artist will need to come up with a different image from the way a professional photographer would do the same thing. Getting a Look at the Photographer’s Pricing You can find photographers by looking in your local phone book or visiting their website or online photo directory (check out www.weddingphotographersdirectory.com). You can Adobe Photoshop 2022 () Crack+ Out of the box, Elements can edit an image in various ways – most prominently you can crop, resize and edit colors. However, when compared to Photoshop, it does not hold the same level of power and its editing functionality is limited. Pros Save your time, create professional content with Elements, which is the best alternative to Photoshop. Cons Adobe Elements lacks some advanced features like the Layer Mask, bitmap layers and adjustment layers. There are important features missing like the large professional library, adaptive images, smart objects and the vector tools. It is the only alternative to Photoshop without the cost. It has a very limited selection of high-quality brushes, gradients, and pattern brushes. Elements is missing the professional workspace, real-time previews and the workflows. It does not support auto-converters like Photoshop. It does not have all the latest updates like Photoshop. Adobe Photoshop Elements has been designed for photographers, graphic designers, web designers, graphic designer and even for the amateur who just likes to edit images. Adobe Photoshop Elements does not have the same price and speed of the application, but it gives you a large library of ready-to-use content to start off with. Elements does not have all the features of the other Photoshop versions like the smart objects, vector layers, adjustment layers and Layers panel. The only alternative to Photoshop is Elements. Here are the differences between these graphics editors. 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Allen joined Everton on a free transfer last summer and is set to become a key player under the Spaniard. The former Swansea and Liverpool midfielder has been at the club for just over four months, but is already looking ahead to next season and claims he is being treated like a “king”. “I think [being a king] is really good, it’s part of the deal,” Allen told Everton Player after completing his first training session. “As a footballer you get paid for your footballing talent and you get paid for other things. “I am paid a lot of money. I’m treated well. I get treated like a king.” Allen claims he has an important role to play at Everton, but is yet to work with Martinez, who replaced David Moyes last month after an eight-year reign at the Stadium of Light. “I don’t know the manager,” he said. “I don’t know Roberto Martinez that well but he has been good to me. I’m looking forward to getting to know him more. “I am confident he will do well. It’s a very big club and I’m looking forward to playing my part in getting success. “It’s a great opportunity. I came in the summer as a free agent. I wanted to see the club progress and try and contribute as much as possible to get Everton where we want to be. “I have come in and I have adapted well. I don’t want it to sound like I am being too humble or that I didn’t want to come but I have adapted well and I am in a good place. “I have settled in well here and I feel comfortable. I am enjoying the club and I am enjoying my football.”Nearly one-quarter of U.S. service members based at U.S. Central Command’s air base in Qatar and another quarter at U.S. Special Operations Command’s headquarters in Tampa, Fla., have been removed from their positions for inadvertently violating a new rule requiring them to cover their faces with a burqa What’s New In? The subject matter described and/or illustrated herein relates generally to electrical connectors, and more particularly, to electrical connectors that are configured to be mated in either a right-angle or horizontal orientation. Electrical connectors are commonly used to interconnect two electrical components or devices, such as in a computer network or telecommunications network. An electrical connector may be mounted to a circuit board to interconnect the board to another circuit board, such as a backplane, daughtercard, or other printed circuit board, or to a panel. For example, a backplane may be provided as an elongated circuit board in a communications or computing apparatus. Various daughtercards, such as daughterboards, daughtercards, connectors, or simply connectors, may be provided as separate cards that plug into the backplane. The backplane may include one or more socket connectors that may be configured to receive corresponding plug connectors. By plugging the plug connectors into the socket connectors of the backplane, the daughtercards may be electrically connected to the backplane. Each socket connector of the backplane may include a receptacle that is positioned to receive a corresponding plug connector of a daughtercard. The receptacle of a socket connector may be configured to mate with the plug connector in a range of orientations, such as a horizontal mating orientation and a vertical mating orientation. For example, the receptacle may be configured to mate with a right-angle plug connector in the horizontal mating orientation and a rectangular plug connector in the vertical mating orientation. To provide for a larger number of interconnections between daughtercards and the backplane, the socket connector may include a receptacle that is configured to receive two connectors of a daughtercard in the horizontal mating orientation and four connectors of a daughtercard in the vertical mating orientation. In some applications, the socket connector is designed to mate with a connector in a horizontal or vertical mating orientation. In other applications, the socket connector is configured to receive a connector of a first size (e.g., in a vertical mating orientation) and a connector of a second size (e.g., in a horizontal mating orientation) simultaneously. Accordingly, there is a need for electrical connectors that include a receptacle configured to mate with a plug connector of a first size in a first mating orientation and with a plug connector of a second size in a second mating orientation.1. Field of the Invention The present invention relates to an exposure apparatus and an exposure method, and more particularly to an exposure apparatus and an exposure method for producing devices, such as System Requirements For Adobe Photoshop 2022 (): [Windows 10] [ ] Intel Processor: Core i5-3300 [ ] Intel Processor: Core i7-3770 [ ] 8 GB RAM [ ] NVIDIA GeForce GTX 760 [ ] NVIDIA GeForce GTX 960 [ ] 16GB available space [ ] Intel HD Graphics 4000 (not supported by some games) [ ] DirectX 12 Compatible Video Card: NVIDIA GeForce GTX 980 Ti [ ] NVIDIA GeForce GTX 980 [ ] NVIDIA GeForce GTX 970 Adobe Photoshop CC 2019 Product Key With Registration Code Free Download [Updated] 2022 Adobe Photoshop CC 2019 With Key Note For more information about layers and how they work, see the box on Working with Layers. * * * * **Comprehensive capabilities**. Photoshop has extensive effects, tools, and other capabilities that enable you to transform your pictures into works of art. A Photoshop class or tutorial can introduce you to the many features that enable you to customize your images. * * * Adobe Photoshop CC 2019 Crack+ Activation Photoshop is a complete picture editor that lets you edit, retouch, and enhance digital images, graphics, and video. It is available for Microsoft Windows, macOS, and Android. It is a free, commercial-grade application. Photoshop comes pre-installed on most new Macs and most Windows PC’s sold after 2012. It is also available for iOS and Android devices. Photoshop is composed of several main sections: The Gui (the User Interface), the Layers panel, the History, the Adjustment Layers, and the Image Correction Panel. The Gui The Gui is the Window where you can access all the sections of the program. It has two parts, the menu bar and the tool bar. The menu bar is the most permanent and consistent part of the Gui. It houses the most basic functions, such as Opening and Closing. It also houses the View Menu, Panels Menu, and Help Menu. The tool bar is the most temporary part of the Gui. It contains the most used functions, such as selections, editing, and adjustment tools. It also houses the Tool Options and Tools Panel. This part of the Gui is where you can customize the preference of each of Photoshop’s tools. The Layers Panel The Layers Panel is the workspace. You can use it for arranging your photos or drawing your own layers and animations. It contains also the Styles, Adjustment Layers, and History panels. The Styles Panel The Styles Panel is for general formatting of the layers within your image. It is designed to make it easier to change the formatting properties of your layer. The Adjustment Layers Panel The Adjustment Layers Panel lets you create Adjustment Layers. These are special layers that are used to automatically combine image adjustments into a single layer, instead of making the corrections manually. You use these layers to merge multiple adjustments into a single layer, like highlights, shadows, and exposure. The History Panel The History Panel is where you edit your image history. It contains three slots where you can view the history of your layers and the history of your actions. The Image Correction Panel The Image Correction Panel is where you can correct your photos. You can remove unwanted elements, sharpen and defocus your photos, and retouch photos. Using Photoshop on Windows Sometimes, Photoshop can’t a681f4349e Adobe Photoshop CC 2019 Crack + [Win/Mac] i * * 3 + 1 0 3 * i * * 2 3 * i + 2 6 . G i v e z ( 2 ) . 8 L e t r ( l ) = 2 5 9 * l + 5 7 1 5 8 . W h a t i s r ( 2 2 1 ) ? 5 1 L e t n ( p ) = 2 1 * p * * 2 1 9 7 * p + 1 0 . W h a t i s n ( 9 ) ? 1 4 2 L e t i ( z ) = 6 8 * z + 1 3 0 3 6 . C a l c u l a t e i ( 1 8 3 ) . 8 L e t j ( i ) = 8 * i + 1 2 6 . C a l c u l a t e j ( 1 6 ) . 2 L e t m ( w ) = 1 8 * w + 1 9 1 0 . D e t e r m What’s New in the Adobe Photoshop CC 2019? If you’re in a previous or existing relationship, you may want to consider finding out if there’s a way you can help her out financially; if she’s in a tough spot, one of you may be better at giving than at receiving. But even if she’s perfectly fine, most people do benefit from giving and receiving regularly, and this can help keep things more balanced. When it comes to financial stress, it’s a good idea to do whatever you can to reduce it, but also to know when to push back. If your mate is chronically stymied by finances, you may be able to help out — as long as it doesn’t become too much of an imposition on your own finances. Be ready to compromise, and have a conversation about finances together. If you’re in a committed relationship, you might even want to think about whether you can contribute to an emergency fund. 13) Avoid toxic relationships “Toxic relationships are the single biggest contributor to emotional disorders, including suicide.” — Raisa Bruner, motivational coach This is a tough one. Toxic relationships come in all shapes and sizes, from abusers to partners who are just plain out to cause harm to their loved ones. In these cases, the best approach depends on who’s involved, but you can’t afford to stay in a relationship that hurts you. If you’re in a committed relationship, you should consider whether your partner is deserving of your support — and whether you’re in danger of being taken advantage of. You should consider factors like whether the relationship has a good workable future for you, and whether your loved one is willing to accept your lifestyle. If you’re in the midst of a toxic relationship, you should disengage, and consider whether it’s worth waiting for an improvement that may never come. If you are, on the other hand, experiencing abuse, it’s best to seek the help of a trusted friend or professional you can rely on. There may be ways to improve the dynamics of a toxic relationship, but it’s unlikely anything worthwhile is going to happen on your own. That may sound cold, but it’s true. You are strong, and you have plenty of resources at your disposal. Get help. If you need a friend or loved one’s support, you’re in luck System Requirements For Adobe Photoshop CC 2019: General: OS: Windows 7/8/8.1/10 (32-bit or 64-bit) Processor: Intel Pentium 4 1.6GHz or equivalent Memory: 1 GB Graphics: 1024MB Video card Hard drive: 1 GB DirectX: 9.0c Language: English Network: Internet connection required for online features Accounts: Primary (Online): One account per person. Secondary (Offline): Allows access to all the online features Photoshop CS3 Activation Download 🗸 DOWNLOAD (Mirror #1) Download 🗸 DOWNLOAD (Mirror #1) Photoshop CS3 With Product Key The Photoshop Essentials tutorial teaches you how to use Photoshop basics. In this guide, we’ll show you how to work in Photoshop from beginner to advanced. This Beginner’s Guide to Photoshop will teach you everything you need to know to gain Photoshop skills quickly. The Photoshop Essentials tutorial teaches you how to use Photoshop basics. Installation Download the Photoshop Essentials tutorial. Once it is downloaded, close your browser and open the folder where you downloaded it. From there, open the Photoshop Essentials folder and double-click on the Photoshop_Essentials_with_Steps.psd file. At this point, you should have a blank canvas in Photoshop. Go to the File menu and select New. Name the new document “Lightroom Photos” and press Enter. Load a photo and bring it into the new document. If the image is saved in the Adobe Camera Raw format, you should see the [ACR] button in the navigation bar. Click the button and select Adobe Camera Raw 5.5 from the menu that pops up. From the menu, select File > Open Image. In the Open dialog box, navigate to your Lightroom catalog and select the image you want to open in Photoshop. Select Open and press OK. It will open in Photoshop. If you see the Plug-in Notes dialog box, select Use as Plug-in. Learn how to use Photoshop by watching our video tutorials. Or download our entire list of tutorials that teach you the basics in Photoshop. You can also learn more about the Photoshop Essentials tutorial by looking at the screen shots below. Loading and Saving You can save a new photo or a new page in Photoshop for sharing or editing. Click on the Photoshop icon in the upper left and choose Save. In the Save As dialog box, navigate to your Lightroom catalog. Select Save. Select Save As and navigate to your Lightroom catalog. You have two options for saving in Photoshop. You can Save As and navigate to the Lightroom catalog at the same time, or you can Save and navigate to the Lightroom catalog from the Photoshop pop-up menu. The pop-up menu is one of Photoshop’s most powerful tools. You can quickly navigate between your catalog and Photoshop to open or save files. Photoshop features many types of menus and toolbars. You can adjust your monitor’s brightness Photoshop CS3 Crack Free [32|64bit] Read on for a quick introduction to using Photoshop Elements. Creating Adjustments An adjustment is simply a way of changing a feature of the image, such as brightness or contrast. Photoshop Elements’ basic adjustment tools are fairly simple and straight-forward. Using the top tabs, go to Image – Adjustments and then select an adjustment by clicking on it in the lower half of the tab. If you have the tool available in the toolbox, you can select it as well by clicking in the lower half of the tab. You can access your image’s Basic Adjustments by clicking on the Basic Adjustments tab in the top right corner of the tab. If you only want to make a small change, you can click and drag the sliders to change the brightness, contrast, or saturation. To make a more extensive change, you can type numbers in the text boxes, or click on the menu bar next to each one. For example, type “150” to make the image brighter by 150%. You can find many more examples of how to do that here: Adobe Tutorials. When you are done, click on the OK button in the top right corner to return to the main image window. Saving your changes After you have made all of your changes, you can save your work. If you have saved a document before, the changes you make will be saved under the name you chose. Alternatively, you can save your work under a new name. To do this, go to File – Save or click on the File tab in the top menu bar and then choose Save. Creating new files and folders You can create a new folder and then save a file under it. For example, if you wanted to save all of your best images in a folder named “My Best Photos”, you could right click in the file manager window and choose New Folder. Type the new name for the folder, then press Enter. You will be prompted to choose the type of file you are saving under the new folder. Choose “Image files” and click OK. After you have created a folder, you can type the name of the file you want to save in that folder. After you have done that, type a new name for the file and press Enter. You can change the folder back to normal by right clicking in the file a681f4349e Photoshop CS3 Crack Download [April-2022] * You can use the Polygonal Lasso tool to select a specific portion of an image, such as an object, and then use the Lasso tool to draw a path. The selection within the path becomes a new layer or is merged with the background. * You can use the Rectangular Marquee tool to make selections in different areas of an image. * You can use the Magic Wand tool to select a specific area of an image. * You can use the Pen tool to create different kinds of effects. When you use the Pen tool, you can draw with a freehand line or use various other tools, such as the Elliptical Marquee tool, to modify the shape and size of the line. You can change the width of the line, the line color and the direction you draw. You can use the Gradient tool to create a gradual change in color or intensity. * You can use the Blur tool to apply slight blur effects to a picture. You can also use the Grainy Effect tool to make minor adjustments to the appearance of an image. * You can use the Spot Healing tool to make small corrections to specific areas of an image. This tool is great for repairing spots and other imperfections in an image. * You can use the Content-Aware Fill tool to make slight adjustments to an image that you want to be completely accurate. For example, you can use this tool to fill in additional objects that are in an image. It is important to have a separate layer for each of your tools or effects. When you draw or paint in an image, you draw on a layer, and when you use the Stroke Path tool, you create a path that resides on a layer. If you need to combine two or more layers, then you simply use the Layer | Combine | Merge Layers command. You can save space on your hard drive by merging the layers into a single layer. You can do this by using the Layer | Flatten Image command. When you flatten a layer, any effects on that layer are removed. You can flatten a layer to save a lot of space when you’re working on a large file. What’s New in the Photoshop CS3? Abigail Reardon Abigail Reardon (born July 10, 1991) is an American para-alpine skier. She represented the United States at the 2010 Winter Paralympics. Personal information Born on July 10, 1991, Reardon’s early diagnosis of Spinal Muscular Atrophy was announced to her family when she was four years old. She competed in her first Paralympics in Vancouver in 2010 where she placed fifth in the Women’s Downhill, Slalom, giant slalom, and Super-G events. She won a bronze medal in the Super-G. In 2012, she competed in the 2012 Summer Paralympics and placed seventh in the Women’s Giant Slalom. References Category:American female alpine skiers Category:Alpine skiers at the 2010 Winter Paralympics Category:Alpine skiers at the 2012 Winter Paralympics Category:American sportswomen Category:1991 births Category:Living people Category:Paralympic alpine skiers of the United States Category:Medalists at the 2010 Winter Paralympics Category:Paralympic bronze medalists for the United States Category:Sportspeople from Bostonwith the light intensity of the moon shining last night we could see some things tea time nice weather is always an unexpected thing finding grace they say having a baby is like having a pair of shoes they don’t fit in the boot of your car not everyone who is pregnant is happy about it is what they tell you have a drink have a lie down yes be quiet it is on the list you might not sleep getting up early, eating right, drinking lots of water, and taking it easy your body is a temple you don’t have to like it you have to accept it you are a god you are the lord of all creation deal with it there are people who think not getting pregnant is a sin and there are others who think it is a gift you can do it even when you are homeless even if you want to keep it because yes, they really are that good yes, give birth to it yes, breastfeed it yes, even System Requirements For Photoshop CS3: OS: Windows 8.1 64-bit (including Windows 7 and Windows Server 2008 R2), Windows 10 64-bit (including Windows 8 and Windows Server 2012) Processor: Intel(R) Core(TM) i7-2600, 2.5 GHz or above Memory: 8 GB RAM Graphics: NVIDIA GeForce GTX 660 or ATI Radeon HD 7770 with 1 GB VRAM DirectX: Version 11 Storage: 50 GB available space Sound Card: DirectX compatible sound card Input: Keyboard and mouse Photoshop EXpress Free For PC Photoshop EXpress Crack Free Latest * Macphun’s Photoshop tutorials (www.macphun.com/tutorials/photoshop) offer many helpful Photoshop tutorials that you can watch at your own pace. ## Other Supported Programs There are numerous other online video courses for free available on the internet, but the following all offer a free trial, so that you can get an idea of the program’s interface before you have to make a purchase: * **PaintShop Pro HD:** www.paintshoppro.com/youtube. * **Red Giant’s VSCO:** www.redgiantonline.com/vsco. * **VideoBash’s basic video editing:** . YouTube is the largest video hosting website in the world. Numerous channels feature free video editing software tutorials. ## Cameras Early DSLR cameras support the MOV recording format, but the professionals have been clamoring for a format that has video features as an addition to the still photography capabilities. A number of software applications do this; VideoStudio Pro X ($100) is one of them. It supports a number of video and image formats for editing and outputting. There are many other freely available applications.
* **Canon’s Digital Photo Professional:** www.usa.canon.com/cusa/portal/us/en/business_services/sp/products/multimedia_products/photography.html.
* **EffinAV’s Digital Video Converter:** www.effin.com/digiconv/.
* **KC Magic’s Kodak’s ImageShare:** www.kjmagic.com/en/technologies-technology/solutions/imedia.html.
* **Klaipeda USA’s Motion Video:** www.klaipeda.com/apps/products-about-us/motion-video.
* **NCH Unitor Pro’s Reunion Studio:** www.nchunitor.com/products/unitor-pro/.
* **Red Giant’s Red Camera Suite:** www.redgiantonline.com/red-camera.
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Features
Here is a list of Photoshop elements features.
1. Any Adobe Photoshop is required.
2. No licenses or registration is required.
3. No cloud services.
4. It requires minimum 4GB RAM.
5. No external hard drive.
6. You can use mouse.
8. All the element is free.
9. There is no watermark on any of the images.
10. You can enjoy a minimal browser pop-up.
11. It does not have any 3rd party software.
12. It is a user-friendly graphics program.
Using Photoshop Elements
In this article, we will discuss how to use Photoshop element effectively. If you are not yet using Photoshop Elements, then you should start to use it.
If you are a photographer, then Photoshop Elements is the perfect tool to optimize your images for all types of devices and screens.
All the high-quality images you have taken need the right editing and color correction.
If you use this software, you can edit the print size, convert color, image size, brightness and contrast, etc.
Some of the Photoshop elements features are as follows:
1. Smart object
2. Undo function
3. Transfer and Embed
4. Fill layer
5. Stroke filter
6. Vector brush and filter
7. Video overlay
8. Animation
9. Animation and Pen tool
11. Fast search.
12. Export your images to various formats.
First of all, please install Photoshop elements.
2. Click on Enable updates automatically to perform a Software Update.
3. Click on Settings and Account, create a brand new account and enter it in other programs.
4. Go to Programs and then finally to Settings.
5. Click on Account, to enter your account and create a new account.
6. In that window, select Account and in New Adobe Account window, create a new account.
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Photoshop EXpress
10.7717/peerj.9036/supp-2
What’s New in the Photoshop EXpress?
Q:
UITabbarcontroller getting undesired navigationBarColor on selected tabBarItem
I have a UITabbarcontroller which gets its navigationBarColor from the root view controller.
I have a detail view controller which just calls a navigation controller to the root view controller, and the root view controller sets the correct navigation bar color for the detail view controller.
However, when I navigate to the detail view controller and return, the selected tab color is white, instead of the black color I set in the root view controller.
I’m setting this in the viewDidLoad method of the root view controller:
self.selectedIndex = 0
and this in the viewDidLoad method of the detail view controller:
navController.view.backgroundColor =.Black
navController.tabBar.tintColor =.Black
Does anybody have any ideas why the tab bar is showing white instead of black?
Thanks.
A:
Ok, I figured it out. I had a subclass of UITabBarController which I wasn’t setting a navigationBar colour on.
I guess this only works if the tabBarController is root.
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System Requirements:
OS: Windows 10, Windows 8, Windows 7
Windows 10, Windows 8, Windows 7 Processor: Intel i5, i3, i7 (Core i3 and i5 OK)
Intel i5, i3, i7 (Core i3 and i5 OK) RAM: 2 GB
2 GB Graphics: NVIDIA Geforce GTX 760 (Not Geforce GTX 960, has been updated)
NVIDIA Geforce GTX 760 (Not Geforce GTX 960, has been updated) DirectX: Version 11
Version 11 Free Disk Space
Photoshop 2021 (Version 22.2) Crack+ (Final 2022)
Photoshop Elements is free software and easy to use and can help you create basic images. It’s often what I recommend as a first editing program for beginners who want to start on their image journey. Chapter 18 shows you the basics and how to use Elements.
Both Photoshop and Photoshop Elements can do a bit more than just enhance your photos, but Photoshop has more powerful editing tools that are difficult to learn, so I still prefer it for the best results.
As computers have become more affordable and have grown in power, Photoshop’s rivals have developed. I’ve included a list of powerful photo-editing tools that may make Photoshop look like the final frontier in image editing.
Plug-ins
Plug-ins are add-on computer programs that can enhance a computer application. Some plug-ins are only available for certain applications, but you can use them for other programs as well. Plug-ins are only as good as the program they are for, so you need to choose them wisely.
After selecting a photo for editing and hitting the Organize button, you see a dialog box similar to the one shown in Figure 3-1.
**Figure 3-1:** Organize your photo to prepare for editing.
Photoshop includes plug-ins for both editing and organizing. Plug-ins with the label Placeholder are only there to show you what the effects of changing settings might be.
Placeholder labels are based on Aperture, Lightroom, or Photoshop Elements.
Before you begin editing your photos, you may want to consider downloading one of these free plug-ins if you plan to use them. Although these plug-ins won’t modify your original image, they can give you some idea of the effect that changes in exposure and white balance have on a photo.
If you plan to use these tools, you’ll need to download them and install them as plug-ins on your computer.
If you’re not sure which one is right for you, always go to the web site that supports the plug-in rather than the manufacturer’s site. Often these sites have the latest versions and review the latest news about the plug-in. Although there may be other manufacturers of similar plug-ins, they usually aren’t as well known as Adobe or Apple.
Programs that are commonly used as plug-ins
Photoshop 2021 (Version 22.2) Torrent (Activation Code)
However, the design and use of a graphic editor can be pretty specific. At the best of times you might be working on a project that requires software in a particular stage of development. Whether you’re writing code, editing audio or designing an image, you’re usually working in a particular scope, with particular rules in place to ease your workflow.
The order in which you perform these tasks usually follows a logical sequence: arrange/arrange, edit/edit, finalise. You have to plan your workflow in a way that works for you. It’s not always the case, but you could edit for a couple of hours and then type a quick email.
The order of steps in Photoshop is completely different.
You will often work with images. A lot of them. Sometimes, once in a while, you start a new project. If you’re new to Photoshop, it’s a little intimidating at first – you’re in an unfamiliar environment. There are different windows, different panels, different styles of menus. You’re not used to clicking the canvas to start your project. It’s a bit like wearing a new pair of shoes. Initially, you won’t know what the buttons do, or how to use the tool palette.
The first thing you need to do is familiarise yourself with what Photoshop Elements is and how it works.
A simple workflow diagram
A workflow diagram is a quick visual aid for explaining your Photoshop workflow. It can help you think about your workflow and organise the information you need to work efficiently.
Everyone is familiar with a workflow. It usually looks something like this:
This workflow is a familiar one. It’s used for a lot of different projects; from designing to coding to managing your social media accounts. There are a number of different ways to do this.
This is an example of a work flow:
Similarly, this is an example:
And this is a workflow:
If you’re familiar with the diagram above, you’ll know that the stages of this workflow are predefined. In this case, there are stages for web development, graphic design, blogging and more.
When it comes to workflow diagrams, you need to ask yourself a few important questions:
Do you need an overall workflow for all your projects?
Do you need a workflow for each project you do?
Are the steps in your workflow flexible?
Can you move things around?
Do you
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Photoshop 2021 (Version 22.2)
WKW Sports Cars
WKW Sports Cars, formerly known as Wahconah Mountain Motorsports Inc. until 2010, is an American auto racing team based in New Milford, New Jersey. The team currently competes part-time in the USAR Pro Cup, NASCAR K&N Pro Series East, ARCA Menards Series, and Lucas Oil Pro Motocross Championship. WKW is owned by Jeff and Michael Kirkpatrick, and was founded in 2009, by Chris Ng and Kevin Kane. They have multiple wins in the ARCA Menards Series, including a 2009 NASCAR Camping World East Series Championship. The team also has a relationship with the Victory Lane Motorsports and Big Cat Motorsports, two other teams in the sport.
Racing career
Wahconah Mountain Motorsports
Wahconah Mountain Motorsports was founded in 2009 by Chris Ng and Kevin Kane. The team ran in the ARCA Menards Series in 2009, and would begin a relationship with Lucas Oil Raceway and the Lucas Oil Pro Motocross Championship for 2010.
WKW
WKW was founded in 2009 by Jeff and Michael Kirkpatrick. The team ran the whole year of 2009 in the ARCA Menards Series, and entered 10 races in the NASCAR Camping World East Series in 2010. During the 2011 racing season, the team’s focus was on the USAR Pro Cup, and they ran five races in the series before returning to full-time ARCA competition. Jeff will continue to be the team’s Owner and Director, while Michael will focus on business matters for the team.
ARCA, USAR, and Lucas Oil
WKW will run five USAR Pro Cup races in 2013. The team returns to ARCA for two races in 2014. WKW also races in the ARCA Menards Series, NASCAR K&N Pro Series East, and Lucas Oil Pro Motocross Championship, with the team usually competing in at least three series at a time.
Mark Your Calendars:Lucas Oil Pro Motocross Championship Season Premiere The Lucas Oil AMA Pro Motocross Championship Presented by Motul will return to the COTA Motorplex in Austin, Texas, for the fourth consecutive year on Saturday, May 10, 2013 with the 54th Running of the Foleys British Grand Prix presented by Motul.
They have multiple wins in the ARCA Menards Series. While competing in the Lucas Oil Pro Motocross
What’s New In Photoshop 2021 (Version 22.2)?
Fishnets
The new Pussycat Dolls song is called Fishnets and it’s mostly all about the colour pink.
The song features a crossover from Skrillex, who does the rap at the end of the song. The lyrics are pretty straightforward.
“I like the color pink, I like the color pink
And I like to wear a skirt for my life”
We actually like it, and we think that Pussycat Dolls are singing along to it in their own attempt at cute.
Kiss Machine
The greatest love story of all time, as told by a knob.
We love it because it’s summer, we love it because there’s no plot and we love it because it’s a giant novella on one of the world’s most memorable figures. Love is cool.
“I’ll take you to the sun and when I say sun, I say son,” Minnie Riperton sings in “Lovely Weather”. The song went to Number 1 in the UK and Number 12 in the US.
“Lady Marmalade” is getting plays as we speak because people want to be in love. They want to be able to say “She’s just a little lady, trying to make a living” without any repercussions. They want to forget their problems and not be judged for their failings and be free to be in love.
“Lady Marmalade” was released in the same year as the Happy Days movie, and the lyrics are a perfect parody of that movie, so we are happy.
“My Prerogative” is the first track from “My Prerogative”, the album by The Pretenders. It was released in 1979 and was the first single from the album by the band.
It’s been remixed by Strychnine, which helped make it even more popular, because of the chorus. The song is a great pop song, and without the song there wouldn’t have been an album. Plus it features a great bass riff.
It is strange, then, that it doesn’t appear in an episode of South Park, because it is a heavy favourite of Trey Parker and Matt Stone.
“My Prerogative” also features in their song “Windsurfing”, which is on the album “Cartoon, Paint, and Decide”.
“Dinner For One” is a song by In This Together and reached a peak position of
System Requirements:
Version: 1.4
Test Scenario: LAN
Video: Intel HD4000 or AMD R7 260X graphics card, or better
Audio: 256MB of RAM and 8GB of available hard disk space
DirectX: Version 11
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Photoshop 2021 (Version 22.5) Crack + Free [Win/Mac] [Updated-2022]
Photoshop also has an extensive set of tools used for advanced image editing. Although this program is pricey, it is a great tool for the serious photographer, or anyone who wants to play with their photos. This is an expert level photo editor and some consider it the best photo editor available.
5.4GHz Dual Core
8GB RAM
256 GB SSD with 5GB SSD cache
Intel HD Graphics 4000
Windows 7 & 8
Mac OS X 10.6 and 10.7 or later.
For best performance, OS X 10.8 or later is recommended.
Why Photoshop?
It is the standard in the image editing world.
It is the most user friendly photo editor, making the learning curve easier for beginners.
It was considered the most advanced tool for editing photos before the emergence of the digital SLR.
Developed under the patronage of Steve Jobs.
Convert RAW files to other RAW formats.
Photoshop is very effective for creating images using RAW files.
What Photoshop Can Do
Image Manipulation
Convert RAW files to other formats
Adjust various tone, contrast, color, brightness, exposure and gamma settings
Create new images from scratch using a wide range of tools
Merge layers
Change the perspective of a 3D image
Extract a section of an image
Duplicate an area of your image
Annotate (some fun but useful features included)
Duplicate Images
Slide Shows
Curves
Gaussian Blur
Threshold
Opaque and Transparent
Painting
Spot Healing Brush
Lasso Tool
Brush
Clipping
Eraser
This tool is used to make fixes and tweaks to your image. You can increase or decrease the exposure, contrast, highlights, shadows, and white balance, adjust colors, reduce noise and more. You can also level the shadows and highlights of the image.
History
This is an invaluable tool. Change your settings in this tool. In the History palette, you can see
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Learn to use Photoshop Elements in your freelance design work. Try out some of the applications we’ve discussed here for free. Creative Cloud is Adobe’s subscription-based cloud-based online platform for its creative products and tools.
Where to get Photoshop Elements?
You can buy Photoshop Elements for 89.99 from these sites below: Adobe Store (Adobe.com) Adobe Creative Cloud (Adobe.com) If you already have Adobe Creative Cloud, you can download the application from your Adobe Website. Download and free Photoshop Elements trial version Steps to Install and Open Photoshop Elements Click the image to download the Photoshop Elements application from your Adobe Website. Once downloaded, extract the archive to a preferred folder. The application will open automatically. Open the application. Photoshop Elements is a graphical user interface. You will find most functionality in the Edit>Arrange panel. The buttons in the bottom will be “Photoshop” features. Now the next step is to open the folder where you have just extracted the program and create a new Photoshop Elements document. You can create new documents, open existing files or organize the photos that you already have. The document has to be named “Element”, add a.psd extension and click “Open”. This is the main interface in Photoshop Elements. You can manage your documents and work on them. The Edit pane contains buttons that allow you to work on the image. Click on “Image”, then select the image you want to edit in the “Choose Image” pop-up menu. The Format panel allows you to edit the color of the image and make it black and white. The panel on the top of the image will be black and white. You can switch to a different color mode by clicking on the color swatches. If you double click on the color you want, you will return to the default color mode. The Settings panel allows you to change the document settings for the image. In the General panel you can manage the zoom level of the image, change the background color, add a border, crop the picture and add text. Click “File” to load the image and a new copy of the image will appear. The a681f4349e Photoshop 2021 (Version 22.5) Crack [Mac/Win] [Updated] 2022 Projetos de lei como os que foram apresentados nesta quarta-feira, 14, pela CCJ na Assembleia da República (ACDR) e pelo PSD na esperança de que o projeto de reforma da Previdência seja aprovado “no novo ano legislativo”, estão em ordem das tarefas da Comissão de Aprendizagem e Competência (CAC), encarregue da avaliação do impacto das propostas. De acordo com um balanço que a CAC dá aos parlamentares “foram analisados dentre os projetos propostos”, três deles: o que em princípio implica a introdução de um pagamento para os trabalhadores mais antigos, ou seja, pessoas com mais de 55 anos, para poderem participar na previsão de reforma já na fase de idade da maioria dos trabalhadores; uma mudança na aposentadoria para os trabalhadores da chamada economia de regime de tempo parcial (EETP); e se possibilita a adesão ao regime de pensão complementar em espécies de planos de saúde particular. São três projetos que, seja qual for a aprovação, coloca a revisão do Regime Geral dos Incentivos à Contributividade (RGCI), que serve para distribuir parte dos impostos do IRS. De acordo com o documento, a CAC considera que a introdução do regime de pensão complementar em espécies de planos de saúde particular “não traz qualquer benefício nem imprime qualquer valor, mas acarreta custos para os planos e para os utentes e pode atrair muitas pessoas para as espécies tradicionais de previdência que não correspondem ao regime de pensão complementar”. De acordo com o documento, a What’s New In Photoshop 2021 (Version 22.5)? The present invention relates to an information storage medium represented by a large-capacity optical disc and a digital information recording/playback system using the medium. In particular, the present invention relates to a DVD (digital versatile disc) recording/playback system that considers real-time recording of a moving picture. The present invention also relates to a recording/playback system which can guarantee continuous playback (or continuous recording) upon continuously playing back (or continuously recording) information using playback devices (disc drives) having various access performances. Furthermore, the present invention relates to a recording/playback system which can prevent any playback timing errors of video information and audio information recorded on the medium.Q: HTML/Javascript stored in hidden element I’ve been trying to accomplish something for a while and I’m having problems with it. I’ve got this HTML: and this JavaScript: document.addEventListener(“DOMContentLoaded”, function() { var m = document.getElementById(“m3”); var s = document.createElement(“script”); s.setAttribute(“type”, “text/javascript”); s.setAttribute(“src”, “js/m3_start.js”); m.appendChild(s); }); And this is the content of m3_start.js: (function() { var m = document.getElementById(“m3”); var t = window; function createService(i) { var i; var header = “”, start = function() { return window.localStorage.getItem(“m3start”) === 1; }, stop = function() { return window.localStorage.getItem(“m3stop”) === 1; }; i = document.createElement(“script”); i.setAttribute(“type”, “text/javascript”); i.setAttribute(“src”, “ System Requirements For Photoshop 2021 (Version 22.5): Minimum: OS: Windows 7 Processor: Intel i3 Memory: 2 GB RAM Graphics: DirectX 9.0c Compatible video card Hard Disk: 4 GB Recommended: Processor: Intel i5 Memory: 4 GB RAM Dimension: 300×240×32 mm Download: Free Download: Available on Windows Latest Version: 3 Adobe Photoshop CC Activation Key [32|64bit] Adobe Photoshop CC Crack + Full Product Key Free Download PC/Windows This guide will teach you all about the tools and features of Photoshop CC. You can either use the official tutorial with its lessons and exercises or use the video tutorials on this page. 1. Where to Start Choose between the official tutorial and the video tutorial You can start with either. If you have any prior experience using Photoshop, you’ll find the official tutorial to be a lot of fun to start out with and to keep learning. If you are brand new to Photoshop and want to learn the basics in a step-by-step way, the video tutorials will be an excellent place to start. 2. Basics Layer Selection You start with the basic selection tools to create the first layer of your image. Afterward, you’ll work with many different selection tools for various purposes in Photoshop. Begin by opening a new file by choosing File > New or by pressing Command+N. Click on the Layers icon to open the Layers palette. Click the New Layer icon (top right) to create a new layer. Refining an Initial Selection To refine an initial selection, double-click the New Layer icon in the Layers palette and choose Edit > Select > Modify > Expand. After clicking Expand, you’ll see all of the content in your image on a single layer. You can now create a better selection by changing the Selection Overlay Color (all the colors in the selection tool are customizable) or by changing the selection opacity to see the image more clearly. The selection color changes from gold to blue, as seen here. After selecting the appropriate color, or after adjusting the selection opacity, you may still see areas where the initial selection is ambiguous. You can use the Refine Edge tool to provide more information on your selection. Refine Edge can be accessed by selecting Edit > Refine Edge or by pressing E on your keyboard. To refine the selection, first zoom in on areas of your image that you don’t want included in the selection. You can zoom in by using the Zoom tool (Z) on your keyboard. Zoom in to find the areas of the image you want to select. You can crop the area that is selected by pressing the C key. You can also adjust the selection by using the Selection Brush tool (P). Be sure to zoom out to see the area you are working with. Adjusting the Selection Brush Adobe Photoshop CC Crack+ Free PC/Windows [Latest] 2022 1. What is Photoshop? Photoshop is a product developed by Adobe Systems. It is one of the best design tools that you can use in your computer to edit and craft different types of images, such as graphics, photographs and live videos. Photoshop is a multi-platform graphics software. This software is one of the most expensive and expensive photography software you can buy. This software is not free, and you have to pay for its full version. Photoshop full version is available on both Windows and Mac versions. In this article, we are going to see Photoshop elements – free Photoshop alternative. The free Photoshop elements is a small size Photoshop alternative that is loved by many Photoshop users and professionals. It offers all the features of Photoshop elements on a free basis. Photoshop elements has a user-friendly interface and good features that make it popular with all types of professionals. Photoshop is an image editing software that is used by many designers, photographers, web designers, and graphic designers to create and edit their images. Photoshop is a complex software with too many features. But, Photoshop elements is a simplification of Photoshop features. Photoshop is still one of the best design tools you can use to edit your images, to crop and resize your images. Some people are not satisfied with the long learning curve of Photoshop, and a lot of professionals who use Photoshop may be satisfied with Photoshop elements as it does not have as many features as the professional version. Although you have to learn some extra things from Photoshop Elements, you can save lots of time that would be spent learning the complex, long learning curve of Photoshop. Adobe Photoshop Elements is an alternative to Photoshop. Adobe Photoshop elements is a small size Photoshop alternative that allows you to do most of the basic image editing and editing tasks you can do in the professional version of Photoshop. For a beginner Photoshop user, Photoshop elements is a good alternative to the professional Photoshop. 2. What is Photoshop Elements? Adobe Photoshop Elements is one of the best photo editing apps for Windows and Mac. It is one of the most popular photo editing software among designers, photographers, graphic designers and web designers. Photoshop elements photo app can be downloaded for free from the web. Adobe Photoshop elements is one of the best photo editing and editing software that is used by designers and photographers for image editing. Adobe Photoshop elements is a free photo editing software. You can also download Photoshop elements for free from their web page. Photoshop elements is a small version of a681f4349e Adobe Photoshop CC Crack X64 ## The Spot Healing Brush The Spot Healing Brush is a tool that “heals” part of an image. It does this by looking for surrounding pixels that are similar to a particular pixel in the damaged area. These pixels are then used to create a replacement pixel in the damaged area. Even though this tool looks and works similar to the Healing Brush tool, it is not exactly the same. In this tool, you can select the area that you want to repair with a whole range of settings from Gaussian Blur to Feather Size, as shown in the figure.  What’s New In Adobe Photoshop CC? /* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * “License”); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an “AS IS” BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.cassandra.io.sstable; import java.io.IOException; import org.junit.Assert; import org.junit.Test; public class SegmentioReaderTest { SegmentioReader reader; @Test public void testRead() { Assert.assertEquals(1, reader.read(new byte[]{ 0x00, 0x00, 0x01, 0x02, 0x03 })); Assert.assertEquals(0, reader.read(new byte[]{ 0x00, 0x00, 0x01 })); Assert.assertEquals(0, reader.read(new byte[]{ 0x00, 0x00, 0x00, 0x01 })); Assert.assertEquals(0, reader.read(new byte[]{ 0x00, 0x00, 0x00, 0x00, 0x01 })); Assert.assertEquals(0, reader.read(new byte[]{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 })); Ass System Requirements: Requires a 64-bit PC with a 1.5 GHz processor or higher. OS: Windows 7/8 (64-bit) Web Browser: Chrome 22+ (Note: Supported Web Browser may vary based on game update) For optimal performance, we recommend using a GeForce GTX 660 or AMD Radeon R9 290 with 2 GB or more of dedicated video memory (VRAM). Minimum Graphics Card Supported: Windows 7 – NVIDIA GeForce GT 330 Windows 8 – NVIDIA GeForce GTX 770 Windows 8. Adobe Photoshop 2021 Free Registration Code Adobe Photoshop 2021 Crack Download For PC Producing a Mockup In the case of a mockup, you want to use photographs, line drawings, or even a drawing tool to create the layout or the template for your project, and then generate a computer-generated version of the layout. Suppose you have some ideas about what you want to do, but you still need to get a sense of the visual impact. To do this, you can print out your sketches and conduct an online search for pictures of similar projects to get a visual idea of what you can accomplish with your final product. You can also make a realistic model of the project or sketch in 3-D, as described in the section “Drawing in 3-D,” later in this chapter. Photoshop makes it easy to create mockups with photographs, drawings, and other elements on the canvas. You may want to use elements such as “ tags, as discussed in Chapter 9. To create a mockup with a piece of content, select the content and use the Create Smart Object command. The system creates the image from the original content and stores it in a separate layer. You can then work with the image as a selection and adjust the layers, as shown in Figure 6-11. You can align the position and size of layers within the Layers panel, or in the Layers panel, click the layer thumbnail and then use the Align and Distribute tabs on the Layers panel to move the layers and adjust their proportions. (See Chapter 1 for more information on layers.) Figure 6-11: A Smart Object created from selected content can be edited in much the same way as any other image layer. Adobe Photoshop 2021 Crack + With Key [Latest] 2022 Elements, by its nature, is a simple program to use, so you can learn Photoshop Elements in a few minutes and feel right at home. Elements also has a great community and is very supportive, with a lot of user guides on the internet. To start using Photoshop Elements, you need to download the image editor to your device. Downloads are available for both Mac and Windows users. All you have to do is choose your preferred OS from the download list. These programs allow you to edit images on the go. This means you can work on a portrait of a friend during a trip, or edit a product brochure without having to install Photoshop. If you own a Chromebook, you can download the Elements Classic app. It’s simple to use and requires fewer resources, so it’s a good fit. The best way to become familiar with Elements is to try it out, and there are free tutorials to find on YouTube, as well as with the program’s support forum. When you’re ready to download your first image editing program, here are 10 best programs to help you edit images on the go. Best tools to edit images on the go Panic is a photo editor that will help you quickly make adjustments in your photos. It’s a free app with a simple design. Have fun with this app. It’s great for making quick adjustments to your selfies and resizing photos. Features A wide variety of graphic tools and effects. Adjustments: You can easily adjust brightness, contrast, colors, and more. Support for RAW, JPEG and PNG files. Support for all devices. You can save your edits in.tga,.eps and.jpg formats. Controls A simple user interface, with a slight gradient design. Text tools: You can type text with different fonts. Image mask tools: Once you’ve selected an area you want to mask, you can erase it and apply some filters to the rest of the photo. You can also add frames. You can preview your images in.png,.psd,.tga,.jpeg and.gif formats. Other features include the ability to send your edits to Instagram, Facebook or Twitter, or save them directly to your own Dropbox. Pros Many options a681f4349e Adobe Photoshop 2021 Crack [Mac/Win] [Updated] 2022 Does the timing of endothelin-1 signalling impact upon its vasoconstrictor activity? Endothelin-1 (ET-1) is a potent vasoconstrictor peptide. The time-course of action of ET-1 is complex and varies from 10 s to 10 min. Studies with cultured vascular smooth muscle cells have shown that ET-1 induces changes in the cytoskeleton and cell surface expression of certain proteins but it is not known whether this triggers or delays the signaling events leading to the initiation of contraction. We therefore aimed to investigate the expression of the contractile proteins, to determine which proteins form complexes with endothelial nitric oxide synthase and the availability of some key contractile proteins such as phosphorylated myosin light chain, and finally to investigate whether the presence of ET-1 alters their phosphorylation level during the different phases of action of ET-1. Rat aortic smooth muscle cells were cultured with or without ET-1 for 15, 30, 60 and 120 min at 37 degrees C. Thereafter, the cells were homogenized, total protein was extracted and the expressions of specific proteins were evaluated by immunoblotting. ET-1 rapidly (15-30 min) increased myosin light chain phosphorylation and the amount of calponin. Sarcolemma association of vasoconstrictor receptor kinase (ROCK) with endothelial nitric oxide synthase was observed at 15-30 min. ET-1 also enhanced phosphorylation of the myosin binding subunit of myosin phosphatase (MBS) but had no effect on phosphorylation of myosin light chain phosphatase. Endothelial nitric oxide synthase and ROCK forms a complex that is inhibited by the ET-1-induced phosphorylation of MBS. The early (15-30 min) increase in calponin and ROCK suggests that ET-1-induced contraction is mediated by activation of RhoA/ROCK. The persistent phosphorylation of MBS suggests that this contraction may be sustained and does not require new synthesis of the contractile proteins. A Cautionary Tale About Swift 3.0 – anguirus ====== nallerooth This is a good read, but it’s not true. He didn’t pass a swift What’s New in the Adobe Photoshop 2021? Ampara people’s massacre The Ampara massacre (හමහර පිවිශවීඩන්), also referred to as the Ampara tragedy, was a mass murder of ethnic Sinhalese citizens in Ampara, Sri Lanka (now part of the Eastern Province), committed by a group of military officers in the late 1970s. According to a Sinhalese newspaper (the Sirasa) the event was the result of racism because of the killing was not perpetrated against members of any other ethnic groups. The government has acknowledged the massacre, but denies that it was racially motivated. The massacre was the subject of the documentary film Survivors’ Story in 1988. Incident Between the late 1970s and early 1980s, the country was in a state of turmoil. In 1977, the Navy Mutiny broke out, and an amnesty was declared in 1980. However, on the eve of the amnesty’s repeal, around 100 ethnic Sinhalese inhabitants of Ampara were brutally killed by a group of military officers. The incident was reported in the English language media as the Ampara massacre, and focused on the cruel manner in which they were killed. The alleged perpetrators were the commander of the Ampara Naval Base, Royal Navy Vice Admiral Hector Trevor Dudley, the commander of the Ampara Garrison, Lieutenant Colonel Walter Prime and the commander of the Colombo Garrison, Colonel George Mior Moringhi. The families of both the victims and the alleged perpetrators were interviewed as part of a Sri Lankan documentary, Survivors’ Story, released in 1988. The survivors’ accounts depicted the incident, with the greatest detail given to the moment when the victims were shot. A number of the victims were civilians and were allegedly targeted for being part of the largely pro-democracy, left-wing group, the All Ceylon Muslim Congress (ACMC). Aftermath The government has acknowledged the massacre, but denies that it was racially motivated. The police report on the incident was issued on 10 October 1978, and the officers who carried out the killings were subsequently court-martialed. The incident was also reported in various Sri Lankan papers, including the Sinhala-language Sirasa. The massacre prompted the Emergency Regulations Ordinance, 1982. The massacre also had implications for the military regime, System Requirements For Adobe Photoshop 2021: Supported OS: Mac OS X (10.7 – 10.10) Windows (Vista / 7 / 8 / 10) Virtually any modern PC. Drivers: Latest Nvidia drivers are required. Latest ATI or AMD drivers are required. Controls As in normal arcade games, you can use arrow keys to move, space bar to jump, or “X” to fire, as well as the standard “Z” for the grappling hook. 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Even though it’s not as popular as Photoshop, it’s still in very wide use, and many website designers and authors would argue that Dreamweaver is now the industry standard. It offers a layout program, publishing program, content management system, and content conversion. Dreamweaver has a layer-based editing system that’s similar to Photoshop’s. However, the program is text-based, so it’s not an easy program for those who feel like they’re colorblind. (It can autocorrect a person’s name into a different spelling, so you can bet if it can guess your name, it will!) In addition, it doesn’t offer a layer-by-layer editing system, so it’s not ideal for complex editing tasks. Dreamweaver’s contrast to Photoshop is its extensive ability to manage layout and page elements. I use Dreamweaver for the graphic and page layout, while I’m done with it when I’m done, so I prefer to use a layout program for this function and find Photoshop more useful for photo editing and retouching. * _Dreamweaver For Dummies_ by Erin Putman ## GIMP GIMP is a free open-source image manipulation program. For the designer who is just starting out, GIMP is ideal. Its feature set is limited when compared to Photoshop, but it can be used for all the same image editing tasks you can do with Photoshop. GIMP is layer-based and uses a steep Adobe Photoshop 2022 (Version 23.4.1) For Windows Free As Photoshop Elements is currently free software, you cannot purchase a license in order to install the software on a computer. However, you can download and use a free trial version before purchasing a license. Some services like Adobe Stock may require Adobe Photoshop Elements to function in the background. Subscription Software During an active subscription, Photoshop Elements is updated as new versions are released. Subscription software is not necessary for new users but is recommended to those that are already using Photoshop. The yearly cost of a subscription is8.99. Adobe Elements vs Photoshop Elements Adobe Photoshop Elements is a version of Photoshop for photographers. Elements is a cheaper alternative to the complete professional version of Photoshop. Photoshop Elements, however, does not include the following tools: Layers Clipping masks Wet and Dry Effects Adjustment Layers Auto-Align Images Video Trimming Photoshop Elements is more of an image editor than the complete version of Photoshop. Adobe Elements vs Photoshop Adobe Photoshop is probably the most famous image editing software. However, it is no longer free due to maintenance and development cost. Photoshop Creative Cloud, the paid-for version, is now $19.99 each year. Photoshop Elements is the name of the free version of Photoshop. Photoshop Elements 10, was launched on October 24, 2015 with the tagline, “Quick Start, Powerful Features”. You can use Photoshop Elements with Photoshop’s PSD file format. Photoshop Elements is mainly for simple image editing. Its features are similar to the basic image editor, Paint Shop Pro. Photoshop Elements 10 can import PSD files from Photoshop 7 and up. Adobe Photoshop Elements Adobe Photoshop Elements, which was previously called Photoshop Elements, was launched on March 7, 1998. It was a free photo and image editing software. It had a simpler interface, lacked some advanced features and lacked some image editing tools. The Photoshop Elements 8 software is the last version of the program to still be supported by Adobe. Adobe ended their support for Photoshop Elements 8 on July 12, 2017. Adobe offers an unsupported option until then. New versions of Photoshop Elements are created and released to fix bugs, add new features and improve the program. Adobe Photoshop Elements has an “elements” at the end of the name. Key Features a681f4349e Adobe Photoshop 2022 (Version 23.4.1) Product Key Restricted solid-phase secondary amine reactions. Solid-phase transformations involving the widely used secondary amines of chloro- or bromoethyl amine, methyl or benzyl amine have been examined and found to be effective. Thus, use of such a secondary amine as activator for a BOP-hydrogen sulfate solution is shown to be as successful as the use of H+ or metal hydrogen sulfates. Both acidic and basic catalytic amounts of the secondary amine react with BOP-hydrogen sulfate in water, at room temperature, to give the corresponding sulfamidates, methyl or benzyl methoxy sulfamate, after about 0.5 h. After 1 h reaction time, a mixture of 70-80% of the product, and 20-30% of excess amine is isolated.US public opinion seems to be swinging back against Guantanamo, with a majority now favouring its closure even though most don’t know what’s happened in the prison, a survey finds. A Washington Post/ABC News poll reveals that 54 per cent of Americans think Guantanamo ought to close as soon as possible, including 31 per cent who think it “should be closed within the next year.” The percentage who would prefer to see the prison open is 24 per cent, down from 32 per cent just six months ago. A majority of Republicans (61 per cent) and Democrats (56 per cent) favour a speedy closure of the detention facility, while independents are split (50 per cent). Two-thirds of those surveyed say they have heard little or nothing about a hunger strike at the prison. The dispute centres around whether it was U.S. authorities or the prisoners who caused a desecration of a Koran at Guantanamo in late November. Just 11 per cent, however, are either “totally” or “mostly” aware of the controversy at the military-run prison. A significant number of voters (40 per cent) don’t have a firm opinion about whether the prison should stay open, while another 14 per cent are undecided. The poll surveyed 1,103 registered voters from Dec. 7 to 12 using telephone and online techniques. The margin of error was plus or minus three percentage points. On Friday, President Barack Obama and the Pentagon said the riot, which caused minor damage to some cells at Guantanamo Bay, would not impede Pentagon planning for the What’s New In? /* * Copyright (c) 2010 SimpleServer authors (see CONTRIBUTORS) * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the “Software”), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package simpleserver.network.codec; import simpleserver.util.UnsignedNumber; public class BlobInfo { public final String fileName; public final String serverName; public final int fileSize; public final int freespace; public final long fileModificationStamp; public final long lastFileReadStamp; public final long fileLastWriteStamp; public BlobInfo(String fileName, String serverName, int fileSize, int freespace) { this(fileName, serverName, fileSize, freespace, -1); } public BlobInfo(String fileName, String serverName, int fileSize, int freespace, long fileModificationStamp) { this(fileName, serverName, fileSize, freespace, fileModificationStamp, -1); } public BlobInfo(String fileName System Requirements: This mod is TOS18.10.25 In order to install the mod, you need to download a modpack. 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(You’ll learn more about this dialog box in Chapter 3.) By default, Photoshop opens your image and displays it in the Background Image area, as shown in Figure 1-16. This area is also where you arrange and position all your layers and tools. (For more on that, see Chapter 3.) Figure 1-16: You can add new layers and arrange them in the Background Image area. At the bottom of the workspace are the menus and their options. These functions are like the tools of your trade — helpful in assisting you with your image-editing tasks. Your new empty document should resemble the blank document shown in Figure 1-17. Note that Photoshop displays your image as a Background Image. To change this, choose Background⇒Image. Click and drag the image to a new location if you want to move it. Click and drag a border around it if you want to crop the image or you want to create a new image by using a pre-defined template. (See Chapter 3 for more on the Blank document.) Although the default for creating a new document is Blank (unfilled), you can also create a document with a photo in it. To do this, click the Customize button at the top of the screen. You then see a dialog box where you select the type of image you want to use. Choosing a photo adds the image to the document. You can also choose an image from a folder on your hard drive. You can create a document from your existing image that’s already open in Photoshop. Right-click the image and then choose Image⇒Open as⇒Photoshop Document. Photoshop then displays a menu of available files, as shown in Figure 1-18, allowing you to select the existing file to open, or you can create a new file from scratch. Photoshop makes a new document, saves it, and opens it. However, choose Layer from the File menu to Photoshop 2021 (Version 22.4) Crack With Keygen Subscription required Photoshop is a powerful tool but it’s also quite a complex program to use. If you use the program at all, you’ll need a subscription that includes access to the most recent version of Photoshop at no additional cost. Don’t have Photoshop? You can download it for free. Tip: Photoshop.com offers the latest version of Photoshop at no cost, but you may need to create a username and password to download it. After installing Photoshop, you can use your existing credentials, or create a new one. Save these shortcuts to your computer’s desktop: Photoshop Ctrl + S (Windows) or Command + S (Mac OS) F5 Mac users can also add.psd as a shortcut to the desktop: Command + Shift + F5 (Mac OS) Photoshop CC Ctrl + S (Windows) or Command + S (Mac OS) F5 Mac users can also add.psd as a shortcut to the desktop: Command + Shift + F5 (Mac OS) Photoshop CC 2018 Press Shift + S (Windows) or Option + S (Mac OS) F5 Mac users can also add.psd as a shortcut to the desktop: Option + Shift + F5 (Mac OS) Lightroom Ctrl + S (Windows) or Command + S (Mac OS) Ctrl + F5 (Windows) or Command + F5 (Mac OS) Lightroom CC Press Shift + Ctrl + S (Windows) or Shift + Option + S (Mac OS) Ctrl + F5 (Windows) or Command + F5 (Mac OS) Lightroom CC Press Shift + Shift + S (Windows) or Shift + Option + S (Mac OS) Shift + Ctrl + F5 (Windows) or Shift + Command + F5 (Mac OS) Lightroom CC Press Ctrl + F5 (Windows) or Command + F5 (Mac OS) Lightroom CC 2018 Press Shift + S (Windows) or Shift + Ctrl + S (Mac OS) Shift + Ctrl + F5 (Windows) or Shift + Command + F5 (Mac OS) Lightroom CC 2018 Press Shift + Ctrl + F5 a681f4349e Photoshop 2021 (Version 22.4) Crack + Registration Code Q: Setting a condition on Gif when Gif is triggered on mouse click I want to show a Gif image (not jpg) when a user mouse clicks on a link, but that link gets clicked on only some cells. I have it all set up in js fiddle. if($(this).attr(“id”) == 0) //click on cells A, B, or C. I need to use something like…if(this.id = 0) “but not sure how to implement into jsfiddle.
HTML
CSS
.cell1,
.cell2,
.cell3 {
background-image: url(
background-position:center;
width:100px;
height:100px;
display:block;
float:left;
text-align:center;
}
JS
$(document).ready(function() {$(“.cell1”).click(function() {
$(“.cell1”).attr(“id”, “1”); });$(“.cell2”).click(function() {
$(“.cell2”).attr(“id”, “2”); });$(“.cell3”).click(function() {
$(“.cell3”).attr(“id”, “3”); }); }); A: You can also use class selector:$(“.cell1,.cell2,.cell3”).on(“click”, function() {
$(this).attr(“id”, “1”); }); Q: Is it a bad idea to display fixed width columns of content in fluid widths? On my site, I want to let the background of the site remain fixed width, so that mobile users can read the site without scrolling horizontally and forcing them to pinch in order to read certain content. So, my question is: is it a bad idea to display fixed width columns of content in fluid widths What’s New in the Photoshop 2021 (Version 22.4)? Q: Formal way to describe every number in base b Is there any formal way to describe every number in base b? In other words: how would you write [1]10 in base b? A: You can do it using the binomial representation of the number. If$n$is the number, and$n=2^k\cdot m$, where$m$is the power of$2$, then the binary representation is simply $$n=(b^k)\cdot b^m$$ In a message dated 8/28/00 3:55:48 PM Eastern Daylight Time, [email protected] writes: > I’ve been assigned to write a software program that reads a data structure and calculates the Average (arithmetic mean) and Standard Deviation (deviation from arithmetic mean). I need to be able to: >> -Assign a value to the Average and Standard Deviation 0 1 2 3 0 1 2 3 2 3 4 5 2 3 4 5 2 3 4 5 2 3 4 5 The program is run in the shell with >. My problem is that the Average will have one entry with the correct value of 6, and every time the program recalculates the Average, the first entry will be updated to be the same value of 6. To calculate the Standard Deviation I would need to output the Total Value to ensure a uniform start, but I would need to have all the partial distributions updated, too. With a search of the Internet I’ve found several libraries that will do this, but I’ve been unable to find documentation on the kinds of data structures these libraries prefer. Thanks for your time. Travis J. Blaine xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Travis J. Blaine Blaine Linguistics FHCRC — Biostatistics 601 North Michigan Avenue Grand Rapids MI -Advertisement- The best way to get research past reviewers is to write a good review first. function estimation from polychromatic calibration data for proton therapy dosimetry. Based on the experience with the ESTRO-EDE dosimetry System Requirements For Photoshop 2021 (Version 22.4): -Windows 7 64bit / Windows 8 64bit / Windows 10 64bit -1 GB RAM -1 GB HDD -1080p resolution -1440p resolution -720p resolution -1080p resolution [PAL] -1440p resolution [PAL] -720p resolution [PAL] The overall Photoshop 2021 (Version 22.0.1) Crack + Serial Number Product Key Full Download For Windows (Updated 2022) 🖖🏿 Photoshop 2021 (Version 22.0.1) Crack [Win/Mac] [Latest-2022] **Adobe Photoshop** Another free download from Adobe is Photoshop CS3 or later. It is the default image editing software of the industry. As with ACR, Photoshop enables users to perform basic image manipulations. It contains tools that allow you to tweak contrast, adjust color, increase or decrease exposure, remove spots, and remove objects. Some advanced editing features are included such as liquefy, blur, add dabs of color, and create graphics. After importing a photo into Photoshop, you can use the editing tools to modify the look of your image. **Note:** Photoshop CS6 offers an even more advanced Photoshop, but in a desktop version. It includes some useful features like advanced editing tools. Photoshop 2021 (Version 22.0.1) License Keygen Free Download (2022) There are many alternatives to Adobe Photoshop and Adobe Photoshop Elements. We will list them here in a combination of free software, paid software and hardware options. 10 Best Photoshop Alternatives in 2020 As technology advances and more non-photographers enter the Photoshop field, more programs are being developed that allow Photoshop alternatives to be used more easily and for free. If you aren’t a professional photographer, graphic designer, web designer or illustrator, and wish to use Photoshop alternatives, then this article is for you. #1. Affinity Photo Affinity Photo is a vector graphics editor and is one of the best Photoshop alternatives. It is more feature-rich than traditional Photoshop but is much easier to use. Affinity Photo is based on the Affinity Designer, a vector graphics editor, and contains a host of features that make it one of the best Photoshop alternatives. That said, Affinity Photo is not as well known as Adobe Photoshop, therefore it can be difficult to find. However, once it becomes more well known, it will surely become one of the most popular Photoshop alternatives. The software provides a number of similar functions to Photoshop, including layers, masks, channels and Brushes. You can also create presets for different page layouts, create vector graphics, and tweak them. Also, there are some of the best Photoshop Alternatives in 2020 for web designers, and it has an excellent companion app called Affinity Publisher. Affinity Photo is a vector graphics editor that is powerful and feature-rich and is one of the best Photoshop alternatives. It also has a very user-friendly and intuitive interface and layout. Affinity Photo is now completely free to use and offers a lot for free. We suggest using the trial version to experience its flexibility before committing. Read the full in-depth review of Affinity Photo. #2. CorelDRAW CorelDRAW is a vector graphic drawing program for artists, photographers, and illustrators that allows them to create various types of images, whether it is creating complex CAD diagrams or printing photos. It is one of the best Photoshop alternatives. The software comes in two editions and the two are quite different. One is CorelDRAW Graphics Suite X8, and the other is CorelDRAW Graphics Suite X7. The graphics suite has features such as drawing tools, bitmap editors, and image manipulation. Corel a681f4349e Photoshop 2021 (Version 22.0.1) Q: Add a time in a pandas dataframe columns I have a dataframe that has three columns (a,b,c) and a date range. a b c date_start date_end 0 30 50 1 20 15 25 2019-06-01 2020-07-01 There are rows that have a date of ‘2019-06-01’ and ‘2020-07-01’ The date_start and date_end columns are the date range. I need to create a third column that says that the row is a holiday between date_start and date_end. Is there a dataframe command to add the third column? A: Here is a method using iloc and np.where + Series.str.split: s = df.iloc[0].astype(str) pd.to_datetime(np.where(s.str.contains(‘\d\d\d\d-\d\d-\d\d’, case=False), s, s), format=’%Y-%m-%d’).astype(int) Output 0 2020-07-01 1 2020-07-01 Name: 0, dtype: int64 Performance Note @ImportanceOfBeingErnest’s comment on performance. I ran some timings to compare our methods. # Create DataFrame with sample data df = pd.DataFrame([[30, 50, 20, ‘2019-06-01’, ‘2020-07-01’], [20, 15, 25, ‘2019-06-01’, ‘2020-07-01’], [0, 0, 0, ‘2019-06-02’, ‘2020-07-02’], What’s New in the? Tag: journals In this article I will be going over how to create Digital Journals. Some of the steps are not for the faint of heart. If you have a total junk skillset when it comes to anything web related, I would suggest practicing on paper. You will need: 1.An account on Tumblr 2.A free iPhone 3G or Android 2.1 Phone 3.Buy a refurbished eMac or PC 4.An 8 gig USB memory stick If you are on a budget and can’t spend much on this, check out my personal eMac review or my review of a refurbished PC (Priced as low as$150!)
1.Firstly you will need to create a Tumblr account ( you can get a free one on the tumblr website). Go to www.tumblr.com, sign up for a free account.
2.Sign up to the app Store and search for The Idiots Guide and download the app. This will allow you to then manage your journals through the app. You will also be able to directly post from within the app.
4.Click on the +new button on the bottom left and select journals.
5.Give your journal a title and description if you want.
6.When you click next, you will be able to choose the theme. A lot of the journals I’ve seen are full on mixed media, full on drawing, mixed media on paper and what not. You can have a look around and decide which one is the best for you.
There are lots of options and you can do really wierd things. Like this guy I’ve made, I’m planning to do a few different themes and see what happens.
Once you have chosen your style, you can choose a template. This is where your graphics for the journal will be stored. The amount of templates available is endless. I don’t really have time to go and find an example but you will find yourself using the same templates over and over.
Once you have picked a template, you can click on edit and customise it to your liking.
You can also add your own fonts. When I did a journal on the theme ‘black and white‘ I used the
System Requirements:
Minimum:
OS: Windows 7 64bit SP1 or newer
Windows 7 64bit SP1 or newer Processor: Intel Core 2 Duo / AMD Athlon 64 X2 5600+ / AMD Athlon X2 4800+
Intel Core 2 Duo / AMD Athlon 64 X2 5600+ / AMD Athlon X2 4800+ Memory: 2 GB RAM
2 GB RAM Graphics: DirectX9 graphics card with 128 MB of RAM (NVIDIA GeForce 8600 GT or ATI Radeon X1600 Pro)
DirectX9 graphics card with 128 MB
Photoshop 2021 (Version 22.1.0) Crack + License Key X64 (April-2022)
Installing Photoshop
Here are the steps to install Photoshop and get it ready to use:
3. Select Photoshop CS6 as the application to be installed.
4. Select the folder where you want to install the application.
5. Click the Next button.
6. Click the Install button.
Photoshop 2021 (Version 22.1.0) Crack + Full Version [Win/Mac]
Like Photoshop, it lets you edit, manipulate, create and manage images, color, depth and more. Unlike Photoshop, it is specifically designed for image manipulation. With image editing, you can perform basic image processing tasks like crop, resize, edit, enhance and colorize images, plus more advanced functions.
Here are 10 of the most used Photoshop elements for image editing and graphic design.
1. Photoshop Elements 10 The only version of the software that we will get throughout the rest of this review is Photoshop Elements 10. There is also an older version of Photoshop Elements but there are no new features added to the software since the 2017 version, so we did not test it.
Adobe Photoshop Elements is a great tool for your photos, images, graphics and designs. It comes with powerful tools like Edit, Enhance, Layer, Page and Smart Objects, but you can also enhance your photos using off-the-shelf editing tools. Use the functions of Photoshop Elements to format, enhance, colorize and sharpen your images.
2. Design Elements 9
In contrast with the previous version of Design Elements, you can tweak your photos and design elements using many different tools. You can use the filters, resizing and cropping tools, the tools to edit text, and also the vector editing tools.
You can use both the Design Standard and Design Premium interface. The main difference between the two interfaces is that Design Standard comes with a generic tool set while the Design Premium tool set is more detailed. Both offer a wider variety of tools.
Design Elements 9 is a great tool for professional design work. It comes with a limited number of tools and is a fairly straightforward interface. But it comes with a lot of useful features like:
Image cropping and resizing;
Text editing;
Vector tools;
Filter tools;
Stroke
3. Corel PHOTO-PAINT 2019
Corel PHOTO-PAINT is an excellent editing and retouching tool. It contains many basic editing features that Photoshop lacks like crop, resize, rotate, change color and enhance. The main tool of the software is the Photo Editor tool. It includes basic editing tools like Curves, Hue/Saturation, Lightness and Black/White, contrast, clarity
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Photoshop 2021 (Version 22.1.0) With Serial Key
Description
Step back and enjoy your neighbors! This lovely home is located just a couple hundred yards south of G Street, which is a charming, quaint residential neighborhood. Immediately behind the home on the eastern side is a large city park, and just on the other side of the park is a cute little boutique shopping area. Today’s modern-day homeowner will enjoy the location and use the backyard as an extension of their living space, which includes the outdoor fireplace and relaxing hot tub.
School Information
Description
Step back and enjoy your neighbors! This lovely home is located just a couple hundred yards south of G Street, which is a charming, quaint residential neighborhood. Immediately behind the home on the eastern side is a large city park, and just on the other side of the park is a cute little boutique shopping area. Today’s modern-day homeowner will enjoy the location and use the backyard as an extension of their living space, which includes the outdoor fireplace and relaxing hot tub.
Property Description
Step back and enjoy your neighbors! This lovely home is located just a couple hundred yards south of G Street, which is a charming, quaint residential neighborhood. Immediately behind the home on the eastern side is a large city park, and just on the other side of the park is a cute little boutique shopping area. Today’s modern-day homeowner will enjoy the location and use the backyard as an extension of their living space, which includes the outdoor fireplace and relaxing hot tub.How to Buy a Custom In-Ear Monitoring Headset?
What are Custom In-Ear Monitoring Headsets?
An in-ear monitor is one of the major components in an in-the-ear hearing aid. The custom in-ear monitor is a custom-designed device that fits your ears perfectly and is comfortable to wear. There are two categories of custom in-ear monitors available. The first one is the open-fit monitor, which is also called a generic in-ear monitor. The open-fit is not custom-designed. The second one is the custom in-ear monitor, which is also called a custom in-ear monitor,
What’s New In Photoshop 2021 (Version 22.1.0)?
There are two types of brushes: Brush Types and Brush Pens.
Brushes can be categorized according to various settings including Density, Diameter, Length, Shape, Spacing, Style, and Underlying Type.
Brush Types can be used in combination with the same Type, Shape, and Style settings of the corresponding brush. Brush Type is determined by the Brush family. Adobe provides a multitude of brush sizes and styles as part of the brush library in Photoshop.
If you need different brush types, brush pens are a good option. Brush Pens are very versatile and they can be used to create brush-like strokes, marks, and line work. You can control the size, pressure, line or shape of the pen that you use.
Adobe provides different types of pens as well as seven pen families. If you need a certain pen style you can use the same settings as the corresponding brush. The shapes, or type of line/brush, that you create with a pen is determined by the Underlying Type.
Let’s look at both brushes and pens together:
Brushes and Pen Types
Adobe introduced several brush types in Photoshop Elements 3. This is a list of the known brush types.
Smudge
Airbrush
Watercolor
Eraser
Fresnel (specular highlight)
Rainbow
Pen Types
Vellum
Watercolor
Brush Pattern
Adobe introduced seven new brush families with Photoshop Elements 3.
Aperture, Drip, Matte, Sketch, Trash, Light and Soft. Pen types are used when the brush type is not available.
Let’s look at each brush type:
Brush Types
Brushes can be used in various modes including Painting, Fine-Line or Scratch, Erasing and Clone.
Painting: A brush is created to create a stroke or outline. It can be used to create a highlight or paint an image.
Fine-Line/Scratch: This mode is used for drawing small lines, circles and dots.
Erasing: This mode is used to erase unwanted areas of an image.
Clone: This mode is used to create a duplicate of an area in an image. Clone enables you to create a copy of pixels and merge it with another area of the image.
Note: Some of the modes listed above will come automatically from a brush.
Below we show examples of each brush in each mode
System Requirements:
3 GHz CPU recommended; 1 GHz minimum
RAM: 4 GB recommended; 1 GB minimum
OS: Windows Vista or later
DirectX: Version 9.0c
When you open your Steam client you will see this message:
Direct X Error: DXGI_ERROR_INVALID_CALL
Yes, I know, I know. I have to get the very latest version of DirectX to run Dirt. Does it really matter? Probably not. The error means that something goes wrong with the graphics hardware and that it cannot load the
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With one click, you can compare the original with the manipulated version, creating instant “before” and “after” snapshots. Photoshop is a must-have for photographers, graphic designers, illustrators, fashion photographers, and many other kinds of visual artists.
Whether a user is just a beginner or professional, Photoshop is an indispensable tool for great-looking visuals. While its overall usage has remained constant, Photoshop continues to offer features that are constantly refined and improved. In general, Photoshop is considered to be among the most powerful image editing tools available.
How the Formerly PHP-only Tool Became the Most Populist, Highest-Paying Programming Language in the World
With a focus on graphic editing and the ability to work on images, photo manipulation, and publishing, Photoshop is probably the most popular image-editing tool. It is especially popular with photographers, illustrators, fashion photographers, and hobbyists who can create and alter personal images. It is also a leading consumer software program, used on computers throughout the world for personal and professional uses.
Photoshop has been available for desktop computers since 1987 as Macromedia’s Photoshop 1.0. Because it was written for Macs, its primary platform was the Macintosh computer. However, Macromedia’s then-chief executive officer, Scott McCloud, announced in 1997 that it would be ported to Windows.
Photoshop quickly became very popular, eclipsing Macromedia’s other graphics programs, Director and After Effects, by 1997. In September 1997, Macromedia released Photoshop version 3.0 for Windows and a few days later announced that it would release Photoshop 1.5 for the Macintosh.
Although the current version (CS3) has continued to get some new features added, most of the programs features have remained virtually unchanged since it came out in 1987, and it retains a loyal, high-end user base. Even though Photoshop has developed quite a following and is considered the world’s best image editing tool, it’s still not as famous as Microsoft’s Microsoft Office suite.
Photoshop is a powerful tool. When used by professionals, it can get pretty complicated, but no matter what, they’ve known it can get complicated. So, for the most part, Photoshop has been relatively unchanged. As a user, there’s a lot of power for doing almost anything, but there are also a lot of complicated ways to do the same task.
Photoshop is a tool that caters to
Photoshop CS5 License Code & Keygen Latest
The most common feature in Photoshop is the ability to edit images. However, it has other features that are worth mentioning:
A layer – A layer is a visual part of an image. It is a part of the composition with its own blend mode and opacity.
– A layer is a visual part of an image. It is a part of the composition with its own blend mode and opacity. The Layers Panel – This is the main way to organize your layers. It gives you a quick look at the layers you have in the image.
– This is the main way to organize your layers. It gives you a quick look at the layers you have in the image. The History Panel – It gives you an overview of all the changes you made to the image.
– It gives you an overview of all the changes you made to the image. The Clipping Path panel – It is similar to the Layers Panel. It gives a preview of the path of the object you’re working with.
– It is similar to the Layers Panel. It gives a preview of the path of the object you’re working with. The Navigation Bar – It is the most important feature of the program. It displays all the layers in the active image and gives you a list of the tools you can use.
Other than this, there are special tools to edit different types of images. You can use the Pencil tool or type text to apply a special effect to the image. In the Export options, you can choose a JPEG image from the format that best fits your needs.
Other than this, you can choose between Layering and Image Adjustments.
The Elements Gallery – This gives you the ability to search for images, add photos to your library or share them.
– This gives you the ability to search for images, add photos to your library or share them. The 3D Warehouse – This is like having a virtual department store to save your creativity. You can search for objects and learn more about them.
– This is like having a virtual department store to save your creativity. You can search for objects and learn more about them. Adobe Camera Raw – This is like the Lightroom or Photoshop: It gives you ways to edit raw images.
– This is like the Lightroom or Photoshop: It gives you ways to edit raw images. The Filter Gallery – This gallery shows you a variety of filters that you can use to give your images a new
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Photoshop CS5
Man City defender De Bruyne to miss another week due to injury
France defender Benjamin Mendy will be out for at least three weeks following a fourth-degree tear to the anterior cruciate ligament in his left knee, manager Pep Guardiola has revealed.
Mendy was injured in the 1-1 draw at West Ham in last Saturday’s Premier League clash.
The 27-year-old was expected to return to first team action in a couple of weeks time but has been ruled out for at least a further week, meaning he will miss the remainder of September and the start of October.
Speaking ahead of Sunday’s game against Burnley at the Etihad Stadium, Guardiola added: “Benjamin had a knee problem and is out for four weeks, it’s his time to rest.”
Mendy has been a regular for City this season, playing 25 games and scoring once.This research effort is concerned with the development of a microcomputer based system for the routine analysis of aeroallergen extracts. The basic methodology for the approach taken is one of pattern recognition with the use of statistics. This technique offers a number of advantages including the ability to deal with the significant amount of data which is generated by current analytical technologies. The overall objective of the Phase I project is to develop a prototype microcomputer system for the analysis of aeroallergen extracts. The specific objectives are twofold: first, to develop a facility for the direct storage and display of the results of the analyses to the operator, including graphic and descriptive output, and, second, to obtain computer outputs which may be used for diagnostic or epidemiologic purposes. In the Phase II effort, the operations currently performed by chemical and biological laboratories in aeroallergen analyses will be performed by the microcomputer system developed in Phase I. The use of the current methodologies for the analysis of aeroallergen extracts will be redesigned to provide a system suitable for the computer based analytical process. The Phase II approach is based on the premise that the microcomputer interface and the programming of the Phase II system will be developed in Phase I, based on the interactions of the user and the system. The facility developed in Phase I will be portable so that it can be used as a result of the Phase II efforts.K-Pop Boutique Owner Cites Business Losses
“Every investment is a gamble,” said Yoon Ah-jin, owner of the boutique Yeonsoong in
What’s New in the Photoshop CS5?
Q:
i have run the migrate and can make the models.py and admin.py
i can get my all users in html
but when i try to write some display in my browser i got error
Reverse for ‘list_users_all’ with arguments ‘(1,)’ not found. 1 pattern(s) tried: [‘list_users_all(\\d+)’] here’s my view : def list_users_all(request): post_list_all = User.objects.all() paginator = Paginator(post_list_all, 20) page = request.GET.get(‘page’) try: posts = paginator.page(page) except PageNotAnInteger: posts = paginator.page(1) except EmptyPage: posts = paginator.page(paginator.num_pages) context = { ‘posts’ :posts, } return render(request, ‘list_users/list_all.html’, context) here’s my url : path(‘list_users/’, views.list_users_all, name=’list_users_all’), and here’s my list_all.html {% block content %} ID Username Website Extra info Edit Delete System Requirements: Compatibility – Origin – The Sims 4 Game – The Sims 3 Game – The Sims 2 Game – The Sims – The Sims Mobile – The Sims Mobile/App – The Sims Mobile Adobe Photoshop 2021 (Version 22.3.1) Key Generator X64 (2022) ✔ Download Setup + CrackDOWNLOAD Download Setup + CrackDOWNLOAD Adobe Photoshop 2021 (Version 22.3.1) Crack+ [Mac/Win] Adobe Photoshop has two major divisions: the desktop application and the mobile app. Photoshop is available for both Mac OS and Windows; we’ll be focusing on the Windows version. An image is an array of pixels, which forms the basis of an entire layer. Adobe Photoshop builds on that array of pixels. As layers are overlaid and transformed, things can be created in Photoshop. You have the ability to erase parts of a layer and replace it with another layer, or blend two layers together to create a new layer. Your image can be divided into groups of layers, and you can apply actions to certain types of layers. Actions allow you to automate things. For example, you can add text to an image, resize the text, change its color, and then save the resulting image. You can create your own layers. You can use guides to help you align objects, and you can even use a path to draw a line. Photoshop also creates a grid for you so that you can measure things quickly and easily. Photoshop layers have transparency. You can see through them. This can be useful when you’re working with complicated images. You can also use a mask to hide parts of the image. Photoshop features layers that you can create yourself. However, you can also use many premade layers. You can use the healing tools to remove and replace portions of layers. You can even use the liquify tool to distort and change an image, making it more interesting. Photoshop has several tools for editing: the selection tool, the paint bucket tool, the eraser tool, the transform tool, and the adjustment tool. You use the selection tool to select an area of the image. You can then add or remove content to that selected area. You can also resize and crop an image. The paint bucket tool is the default tool to add content to an image. You can select a color and then click on an area of the image to have the color added to it. This creates a new layer, which you can then adjust. The eraser tool is used to delete parts of an image. You have the ability to erase anything, including color and more, on a single layer. Using the transform tool, you can reshape an object in an image. You can resize it and change its aspect ratio. You can also alter the orientation of an object. The adjustment tool is a collection of tools that you can use Adobe Photoshop 2021 (Version 22.3.1) Adobe Photoshop Elements is a widely used photo editor for photographers, graphic designers, web designers, and enthusiasts. It is the most used tool for photo editing available on the market today. You might have heard that Adobe Photoshop is used for creating photos and graphic artwork, and Adobe Photoshop Elements is used for photo and creative editing. All of the features of Photoshop are available in both products. However, photographers will most likely be interested in Photoshop Elements instead of Photoshop, since it has a smaller user interface, fewer editing features and is priced significantly lower. You can purchase Photoshop Elements from Amazon in paperback form and digital form. This post will give you an overview of the Photoshop Elements software and the video tutorials that will teach you how to use the software as a beginner. What is Photoshop Elements? Photoshop Elements is a set of photo editing tools for photographers, graphic designers, web designers, and enthusiasts. It is a standalone program, and you have to purchase it, and not share it with your computer. Note that many of the features in Photoshop Elements are similar to, or identical to, those in Photoshop. There are also a few features that are only found in Elements. What Can Photoshop Elements Do? Elements offers basic photo editing functions like resizing, cropping, adjusting lighting and color, rotating, applying filters, and creating special effects. Unlike Photoshop, Elements also has features that specialize in photo retouching and photo cloning. You can download free Elements samples so you can try out the products before you purchase. Elements gives you the option of sharing the images you edit or just keeping them private. When you use Elements to edit your photos, you get to keep the original as long as you save it in a format that is compatible with the program. A set of three tutorials will teach you how to use the software. It is important to understand that Elements is not a graphics program like Illustrator, InDesign, and the other Adobe programs. Elements was designed to be easy for photographers and graphic artists to use. It is therefore important to read the user manuals, so you can fully understand how to use the software. What Are the Advantages of Photoshop Elements? Adobe Photoshop Elements is a popular software for creating photos because it is easy to use, provides many basic photo editing tools, and is priced lower than Adobe Photoshop. The following are reasons why Photoshop Elements is a great choice a681f4349e Adobe Photoshop 2021 (Version 22.3.1) Crack + With Product Key Q: Convert date string to date object I’m trying to convert a date string to a date object. I just want to get a simple Date object. I tried Date.parse(dateString) but it returns a date object that has been updated to this date. For example: Date.parse(“24/12/2013”) = Mon Jan 01 2013 Time zone is UTC Let me know if there’s anything I did wrong. A: You have to convert your string to an ISO 8601 string: var iso = ‘2013-12-24T00:00:00’; var date = new Date(iso); Here is a live example: David B. Rubin David B. Rubin (June 7, 1947 – June 6, 2010) was an American author and professor. Biography David B. Rubin was a native of the New York City suburb of Midwood, Brooklyn, New York. He graduated from Benjamin Franklin High School in Brooklyn in 1964, attended Columbia University and received a B.A. from Yale University and an M.A. and Ph.D. from the University of Pennsylvania. Rubin also served in the United States Army as a Captain, first in the Military Police Corps, and then as an Army Specialist in the U.S. Army Security Agency. He worked for two major defense firms before joining the faculty at Purdue University. He wrote numerous non-fiction books including How to Succeed in Peace (on his experiences in the United States Army), The Corporate Guerilla: A Survival Guide for Business Entrepreneurs, Penetration (on the techniques of the corporate espionage practice), and The Investor’s Advantage: Conversations with the Top Financial Experts. He also co-authored The Business Guide to Social Media with author Peter Diamandis and the novel The Ungodly were written by Zuleikha Robinson. Rubin was survived by his wife and daughter. References External links Obituary in Business Week, June 9, 2010 Obituary in New York Times, June 8, 2010 Category:American male writers Category:1947 births Category:2010 deathsQ: Why When I try to send my Key with SHA1Signature to my wallet it says Signature not valid? I wanted to send my What’s New in the? Intravenous Immunoglobulin (IVIg) is approved for over 30 indications and represents a significant cost burden to healthcare systems. It is considered a “cure” for some autoimmune disease indications, which are chronic diseases characterized by autoreactive pathogenic immune responses. However, as many autoimmune diseases are not curable, they remain symptomatic, have a high burden on quality of life, and thus remain inaccessible to IVIg treatment. Infusion-related reactions to IVIg are well documented. There are two known categories of complications resulting from IVIg administration: positive reactions and negative reactions. The incidence of IVIg-related complications is 1-1.5% of the treated population and mortality rate is less than 0.1%. Subsequent exposure to IVIg in a subsequent regimen is associated with a reduction in the ability of the recipient’s immune system to mount a response to the initial administered dose, resulting in an increased susceptibility to infusion reactions in subsequent administrations. IVIg efficacy may also be reduced in patients with co-morbid conditions, such as systemic lupus erythematosus (SLE), renal disease, or diabetes. There are few existing techniques for reducing the incidence of IVIg-related infusion reactions in individuals with the aforementioned risk factors. In any case, detection of a previous reaction is typically performed on an inpatient basis and is typically done with the aid of FDA-approved EKG and telemetry monitors, which are poorly suited for out-patient use. There is a need for a simple, economical, device that could assist in reducing or eliminating these reactions, such that patients could be treated on an outpatient basis. Furthermore, there are no previously published techniques for monitoring an individual’s IVIg response over time. One factor that limits the ability to monitor individual response to IVIg treatment is the known reduction in IVIg efficacy in patients with established SLE. Likewise, in inpatients with chronic disease, control of the individual’s disease is more difficult because the patient must depend on the medical staff to monitor and treat for disease exacerbation. Although IVIg is primarily used to treat autoimmune disease and related complications, it is also used for a wide range of other indications, including for example, blood and marrow transplantation, chronic inflammatory conditions including rheumatoid arthritis, inflammatory bowel disease, mixed connective tissue disease, Behcet’s disease, multiple sclerosis, myasthenia gravis, System Requirements: Supported titles: Samurai Warriors 4, Warriors Orochi 3, Samurai Warriors 3 Empires, Warriors Orochi 2, Nobunaga’s Ambition Distribution format: Steam Steam’s very own Games For Windows Live service Official Website: DirectX 11 compatible graphics card DirectX 11 compatible GPU over 1000MHz clock rate Windows 7 64-bit or later Windows 8 / 8.1 iPad mini/iPhone 4s/iPhone 5/iPad Air/iPad 5/iPad 5C Photoshop 2021 (Version 22.4) full license License Key Free Photoshop 2021 (Version 22.4) Crack Keygen Free [April-2022] | **FLASH: Understanding the Importance of Levels** — | — Photoshop includes a basic program called Flash, which is a kind of Photoshop Lite. It’s a fast and easy way to create images with the Adobe Creative Suite, and it also enables more general photo editors to create specific effects. If you want to make an image look like a photograph or a painting, you may have to use Flash. Flash is a true raster program, so it’s not like the vector image programs that most designers use. In Flash, there are two different forms for the _levels_ property that together indicate the contrast of an image, or the brightness and darkness of an image. These two properties are the opposite sides of a contrast scale, and the middle part of the scale is generally the correct range. With a balanced image, you might have a middle value of 50, and the top and bottom values of 0 and 100. To tweak the middle value to a stronger value, you’d set the top value to 0, and the bottom to 100. In Flash, the top value is black, and the bottom is white, so the property ranges from 0 to 100, or black to white. Using the gray-scale values in the image, you can adjust color balance and contrast. Many images need some tweaking, which is fairly easy in Flash. Take a look at Adobe’s Web site for more details about Flash. Photoshop 2021 (Version 22.4) Adobe Photoshop is a powerful image manipulation toolset that can be used to modify images in many different ways. In fact, most photographers start out using Adobe Photoshop and later move to Adobe Lightroom or Adobe Camera Raw. Photographers create and modify images using Photoshop. Adobe Photoshop is available for Windows, macOS and Linux, as well as for iOS devices. This article will guide you through each step in the way to install Adobe Photoshop and use it in the best way. Download Adobe Photoshop 2020 We have carefully tested the software version 2020.0.0.3056.2. Adobe Photoshop 2020 is available to download and install via the official website. Adobe Photoshop Elements 2018 Adobe Photoshop Elements 2018 is available to download and install via the official website. Here you will find a detailed review of this software. We have checked it thoroughly and we recommend it. Download Adobe Photoshop Elements Adobe Photoshop Elements is available to download and install via the official website. Here you will find a detailed review of this software. We have checked it thoroughly and we recommend it. Adobe Photoshop for iOS 2019 Adobe Photoshop Elements 2019 for Mac can be downloaded and installed on iPhone, iPad, and iPod touch. Learn how to install Adobe Photoshop Elements 2019 for Mac. Download Adobe Photoshop Elements 2019 Adobe Photoshop Elements 2019 for Mac can be downloaded and installed on iPhone, iPad, and iPod touch. Learn how to install Adobe Photoshop Elements 2019 for Mac. Adobe Photoshop for iOS 2020 Adobe Photoshop Elements 2020 for Mac can be downloaded and installed on iPhone, iPad, and iPod touch. Learn how to install Adobe Photoshop Elements 2020 for Mac. Download Adobe Photoshop Elements 2020 Adobe Photoshop Elements 2020 for Mac can be downloaded and installed on iPhone, iPad, and iPod touch. Learn how to install Adobe Photoshop Elements 2020 for Mac. Adobe Photoshop Elements Editor The Adobe Photoshop Elements Editor 2020 is available to download and install via the official website. Here you will find a detailed review of this software. We have checked it thoroughly and we recommend it. Adobe Photoshop Elements Editor 2020 The Adobe Photoshop Elements Editor 2020 is available to download and install via the official website. Here you will find a detailed review of this software. We have checked it thoroughly and we recommend it. Adobe Photoshop Elements The Adobe a681f4349e Photoshop 2021 (Version 22.4) Crack + [32|64bit] with rice as a staple. However, we found that the number of households using a LPG stove was lower than the rate of LPG stove ownership per household, as seen in Aydin et al. ([@B2]). We think this difference is caused by a policy or law to promote LPG as a cleaner energy source due to its lower emission of SO~2~, NO~x~, and CO compared to the combustion of wood or charcoal. In our study, only 56.3% of the households said that they used the LPG stove regularly, while 89.1% of households owned the LPG stove. This implies that the current policy could be the reason for the low rate of LPG stove usage. The rate of usage of the LPG stove was 74.9% and 57.7% in 2011 and 2012, respectively, in Isparta. In this study, people had different access to gas. While 82% of the households in Isparta had their own supply of gas, 51.8% of rural households did. Thus, households in Isparta that had access to gas may have benefited from the policy while those without access may have not. However, we could not detect a difference in the usage rate of LPG stoves between rural and urban households. However, access to gas varies between urban and rural regions. A recent study conducted in the whole country in 2014, found that the rate of households that had access to LPG was 43.3% compared to the rate of household ownership of LPG stoves which was 78.8%. Within the study areas in our study, access to LPG gas for households was almost universal in Isparta and rural households had similar access to LPG as those in Isparta. However, this region is predominantly rural. High LPG usage rates were seen in urban and rural households of Aydin et al. ([@B2]) while Aydin et al. ([@B1]) found a low rate of LPG usage. LPG is a clean burning fuel that is cheaper than kerosene and charcoal, and there is no emission of particulate matter. However, the main disadvantage of using LPG is that it has a relatively short duration of storage. For this reason, LPG stoves were traditionally used for cooking in the morning and in winter for heating. However, people started to realize the benefits of using LPG stoves during cooking, and had begun using them for What’s New in the? The rest of Canada has not been left out of the retail spending slowdown which is occurring in the U.S. The country’s largest retailers – like Shoppers Drug Mart and Wal-Mart – are reporting disappointing comparable-store sales in Canada, signalling the possibility of retail sales slumping in the coming weeks. Shoppers drug Mart (TSE: SHO), which is the country’s largest drugstore chain, reported a 0.9 per cent year-over-year decline in fourth quarter sales, continuing their “lacklustre growth” at a time when Americans are clocking up their first holiday shopping dollars. They also posted worse-than-expected full-year revenue, bringing in3.25 billion, down 2.1 per cent.
Top 10 retail organizations by market capitalization fall
The data do suggest that Shoppers’ dollar volume growth is slowing, not necessarily declining. They also noted that weekly operations were stable, despite a drop in orders and shipment growth. That’s one of the ways they’re adding to their market share, by growing their weekly operations.
The company’s performance was not as good as what some analysts were expecting, as their numbers had been on the rise for a few weeks.
It came in below what analysts polled by Thomson Financial expected, as they had been hoping for 7.7 per cent growth. The company also missed on its guidance, which was for a 1.1 per cent growth. They also said that the slow growth was still due to a strong U.S. economy in the third quarter, and that their top priority moving forward is to build a stronger business in Canada.
Walmart (NYSE: WMT), with $496 billion in market capitalization, actually reported a slight increase in the fourth quarter. This was a 0.7 per cent increase, although the company as a whole reported a 4.1 per cent fall in sales. Their numbers still posted a strong 8.8 per cent annual growth rate, bringing in$115.5 billion. Comparable-store sales, which is what they consider all stores, totalled $111.5 billion in the fourth quarter. They also reported 8.1 per cent growth in profit, with$12.1 billion in net income.
The biggest loser in their earnings report came in the form of Target (NYSE: TGT), which fell from being the biggest company to lose market cap in the United States to the 10th.
System Requirements For Photoshop 2021 (Version 22.4):
Windows 10 compatible operating systems are supported, however, we do not support Windows 7 and previous operating systems.
Access to a digital representation of the original puzzle (such as an image of the board with the solution) is recommended, but not required.
Puzzles are written in JavaScript and HTML5
The current puzzle at-a-glance:
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Photoshop CS4 Crack+ Full Product Key For Windows
Note
This exercise creates a new copy of the original image. If you want to make this change without a second copy, you can simply click Undo (Ctrl+Z on a PC) in the Layers panel.
# Choosing from the Toolbox
Although Photoshop has many tools at its disposal, you need to consider how and when they should be used in order to maximize your results. A tool is the series of actions and steps required to produce a certain result. In the following exercise, you use all the tools you’ve learned so far in this book in order to create a picture of a candle.
## Exercise 6.4: Do It with Tools
In this exercise, you create a simple image of a candle using the various tools available in Photoshop. Make sure you use all the tools.
1. With the original candle image open, choose File > New and click on Flat Color. Set the color to #FF0800 and name it Candle.psd.
2. Use the round tool (R) on a new layer at the top of your layer palette to draw a simple circle on the layer. Use this tool to create the rough outline of the candle as shown in Figure 6-23.
Figure 6-23. Start creating a new layer for the candle.
3. Create a gradient by using the Gradient Tool (G) and shape the gradient as shown in Figure 6-24.
Figure 6-24. Using the Gradient Tool, create a gradient for the candle.
4
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Google Drive, Dropbox and iCloud are free services with pay-for options. Google Drive and Dropbox are very popular amongst web designers to store files and design assets as an inexpensive means of keeping everything organized on a single platform.
In a large project, you may need to collaborate with other designers and developers. A common method of collaboration is using Google Hangouts Meet for videoconferences. For this, we’ll be using:
Clip Studio Paint
Transparencies
Crisp
Illustrator
Photoshop
Videoconferences are a way to connect with other colleagues.
We’ll mainly be using Photoshop and Illustrator as tools to complete this task, as well as the Google tools we’ll use.
Let’s get started!
Step 1. Create a new document in Photoshop
Have you ever noticed that you couldn’t find a certain design or image in your computer? Or have you ever been looking for a certain image on Google and had a hard time finding it?
This happens all the time. That’s why there are more options in Photoshop. You can see the designer’s files from a centralized location. You can use shortcuts that save a lot of time. You can even add a search function that finds what you need.
In this lesson, we’ll use Photoshop to open two folders, one of which contains a collection of brand new images, and the other, which contains some of the images we’ll be designing. Photoshop will be used to edit both the files and create new high-quality files for uploading to our server.
Step 2. Open Photoshop’s Files panel
In Photoshop you have to move between the Files panel and the Table of Contents (TOC) window. The TOC window is a tool that you’ll use often. It lists the various documents you have opened and allows you to switch to them. In the Files panel, click on the TOC icon to see all your documents at once.
Open Photoshop and click on the File menu at the top left of the interface. If you have Photoshop set to the web builder option (File > Automate > Sketch or File > Automate > Photoshop), you’ll get this screen.
Step 3. Navigate to the folder with
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American English Company would not have lied about their ratings without a good reason. American English Company could have used Western Union to send the $150. It was a way to inform the customer that their rating didn’t change when he made the payment to American English Company. American English Company would not have lied about their ratings without a good reason. American English Company could have used Western Union to send the$150. It was a way to inform the customer that their rating didn’t change when he made the payment to American English Company.
American English Company could not have lied about their ratings because their ratings stay the same when they get paid the money and they can ask for a refund at any time if they had no reason to believe that they weren’t actually getting paid.
The reason they lie is because they want to get money. By lying about their reviews they are making themselves look better than the competitors, while giving the competitors a better image. If you think that the competition isn’t lying then you are probably naive, because I guarantee they are.
Originally Posted by NoDaikon
American English Company could have used Western Union to send the $150. It was a way to inform the customer that their rating didn’t change when he made the payment to American English Company. Yep, I was using Western Union. That way they would be sure that the money was actually being paid to them, but they don’t send a note saying that. They just send the money. …so what should I have done? Originally Posted by NoDaikon American English Company could not have lied about their ratings because their ratings stay the same when they get paid the money and they can ask for a refund at any time if they had no reason to believe that they weren’t actually getting paid. American English Company could not have lied about their ratings because their ratings stay the same when they get paid the money and they can ask for a refund at any time if they had no reason to believe that they weren’t actually getting paid. 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As a not-for-profit organisation, VRA is reliant on membership fees from its members to fund its operations.Q: How to get all the values from a table and return in a text file using SSIS I need to export a datagridview to a text file using SSIS, The Datagridview contains of 7 columns and 10 rows, I need to retrieve all the values from the grid and export to a text file with the headers of the columns. Can someone help with the code to export it What’s New in the Adobe Photoshop 2021 (Version 22.3.1)? Saturday, February 21, 2014 Banker Twitter Seeing the first Suncere list from last year’s tournament, I was reminded of Banker Twitter. You’ve probably heard of Banker’s PBEM game blog, but did you know that there’s a Twitter feed for it? I don’t actually play-by-blog, but I love looking at a game blog and seeing the questions that people are asking about their games. 7 comments: Hi Brandon, Yes, I followed both your blog and twitter. Love it! I just feel like there are a lot of different ways to play. I’ve not played the H2H tournaments (which I don’t think they even last that long), but I do watch them and read through them. I don’t follow games by blog. Sometimes it’s just necessary to play and I can’t spend too much time on a single game, sometimes I want to play a tournament in which I know the meta-game well. If you watched the ROPT tournament, you probably noticed that most games were played in the LAN. For one thing, they have a time limit and players are supposed to plan ahead and set up the contest between opponents. For another, for all I know, a “quick” LC and a “quick” LC3 is not just that (to be clear, I never got that far). I’ve heard that the format of the Episodes ruleset is intended to make each game more about the choices of players than the rules, but who knows? In any case, I’ve been using twitter to ask questions to the people I follow, and I hope that they answer me if I can make an interesting question (and I never complain about not getting an answer, they tend to take that in the positive). The problem is that it works just well for games that I can play, but doesn’t work so well for games that I can’t play (or at least I don’t play-by-blog). If I have to wait a lot for my opponents, there’s not much point in following the game on Twitter. Things change so fast in the world of the internet that I imagine that a couple of years from now, Banker Twitter may not work at all – we’ll see. I think that it’ll be good in any case, and I’m glad that they’re giving some attention to it. I’m not that into social networks, System Requirements For Adobe Photoshop 2021 (Version 22.3.1): Microsoft Windows 7/8.1/10 (32 bit and 64 bit) Intel Dual Core 2.4 GHz (or equivalent) 2 GB RAM 32-bit DirectX DirectX 8.1 (D3D 9.0c) Internet Explorer 11 (latest version) High Resolution – 1440×900 or 1680×1050 Very High resolution – 2560×1440 Path of Exile by Grinding Gear Games You must own the Standard Edition to be able to download the Enhanced Edition. Adobe Photoshop Serial Number Download For Windows [2022] 💚 With a long history behind it, years of experience and thousands of users worldwide, Photoshop is, without a doubt, the industry standard when it comes to photo manipulation and graphic design. In fact, its popularity is so widespread that its name became a verb, much like Google. It is habitual to say that an image has been “photoshopped”, which in the urban dictionary means that it was edited or manipulated, no matter the image editor that was used. Photoshop's popularity relies on its versatility and its impressive feature set, which meets the requirements of professional photographers and artists, advertising specialists and graphic designers. Amazing results can be achieved once Photoshop’s capabilities are mastered and explored to their highest potential. Creativity and imagination are the only limits Photoshop delivers a plethora of tools for image manipulation, while making no compromise on quality whatsoever. Its toolbox includes an overwhelming collection of image editing features both for raster images and vector graphics. As expected with such a powerful and comprehensive application, it requires time, exercise, experimentation and practice to master, perhaps a significant amount of time spent watching tutorials and viewing usage examples to use at full potential. But once mastered, the rich graphics and the astounding images that can be obtained in Photoshop make it all worth it. Give your photos a stunning, eye-catching look Layer-based editing is at the core of Photoshop, allowing image creation and manipulation using multiple overlays. Masks, filters, shadows and various other effects can be added to a layer. With smart auto-correction capabilities, HDR imaging, color management tools, tons of effects and animations, there is no editing task that Photoshop cannot carry out. It allows you to change picture backgrounds and fix imperfections, or use effects and colors to make a photo be much more eye-catching. It is not just editing tools that you have at hand, but also various drawing tools that bring you close to the real experience of painting in watercolor, spray-painting on a wall and achieve effects that you might not thought can be obtained in the digital world. Moreover, neural filters allow you to color a scene with a few clicks, combine landscapes to create collages or a new scenery and change face expressions in your photos. And, if that is not enough, the application’s functionality can be further extended using new plugins available both inside the application and in Creative Cloud. Presenting the Photoshop family It is worth mentioning that the Photoshop family includes mobile tools that work together to provide a comprehensive and unmatched image manipulation suite. Photoshop Lightroom offers powerful image editing tools, Photoshop Express is the mobile Photoshop client that can be used on the go, while the Photoshop Camera is an app that allows capturing high-quality photos. Needless to say, Photoshop seamlessly integrates with other of Adobe’s products, allowing you to import content from Illustrator, for instance. The go-to image editing and manipulation software Photoshop is the emblematic application when it comes to photo editing, managing to challenge your creativity and design skills, while providing the tools and the functionality needed to obtain incredible art and amazing graphics. Thanks to its clever selection tools, its professional-grade editing toolbox and its team collaboration and sharing options, Photoshop’s recognition as the industry standard has, indeed, a solid foundation. Adobe Photoshop Free Download For PC 2022 * • Learn from books, video, websites, and instructors. Learning Photoshop The trial version of Photoshop offers several hours of use per month — not enough time to learn about every tool. First, look to books, video, and the websites and instructors of other Photoshop users. Typically, you find beginners-only online forums where you can download articles that can help you learn. Forums The Adobe Photoshop Cracked 2022 Latest Version website (www.adobe.com) is an excellent place to start for beginners, but it’s where advanced users go. Start a new account and access the Photoshop forum (www.adobe.com/go/photoshopforum) or join one of the more popular Photoshop discussion groups. In a less formal setting, the larger Photoshop community on Facebook (www.facebook.com/photoshop) is a good place to start. The increasing availability of Photoshop tutorials is a boon to beginners, although the quality of many of these tools is uneven and can be misleading. Cheap “Editing” Books Some books tout Photoshop as an easy-to-use tool and offer simple solutions to common problem areas. They may be a bit misleading in that the bookware may fail to cover the more advanced areas of Photoshop. Also, the bookware may not have the careful eye that would catch and point out errors in the bookware author’s work. In the Photoshop community, we see users write books and videos, then review the books and videos by other users. Videos If you’re really getting serious about using Photoshop, look into the range of educational videos that teach from the basics all the way to more advanced issues. You’ll find dozens of videos online. Some are quite good; some are quite bad. The video of choice for beginners is the Tutorial on the Adobe website. In the tutorials, you learn how to use Photoshop by using it. Not only are the tutorials well-written and structured, but they come in at a reasonable length. Intermediate-level tutorials often come from the talented Photoshop expert Pancho and his team of well-known Photoshop guru friends. You can find videos on many of the tools that make up Photoshop, such as filters, 3-D, drawing, painting, tools, and effects. Photoshop Mentor’s online videos are short (under 10 minutes) and have a handy play-along feature. They do, however, not provide the level Adobe Photoshop Crack + Free Registration Code Download [32|64bit] (April-2022) Photoshop Elements 2020 Crack Plus Activation Key & Torrent Photoshop Elements 2019 Crack is a powerful and fast Photo editing software. It is an easy to use image editor. 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Advantages: Photoshop Elements 2020 Crack Plus Activation Key is a fast Photo editing software. It has a simple and user-friendly interface. It is an easy to use tool. It is known for the purpose of photo editing, graphic designing, web design, logo designing and much more. It has a a681f4349e Adobe Photoshop Crack + Full Product Key Free Download X64 Q: How should I incorporate a steel toe cap into a shoe? I’m looking for some additional support for a pair of running shoes I already have. I’m looking to add a steel toe cap to the shoe (I prefer the steel toe cap from the Adidas Adios Boost, pictured below). I was just about to get my new Adidas and was wondering what I should do with my old pair, since I won’t get a new pair for awhile. I’m worried about breaking the old in on the boot itself, and wonder if I should just remove it. A: You should have no problem, as long as the toe cap is the same. The toe cap is typically a separate component (and attached by a frame or sleeve), but the whole upper should be going on there. It’s unlikely to get damaged, but since it won’t go on on it’s own anymore, it’s a good idea to take it off and sort of “stock it up” for easy removal when the new shoes arrive. Something like this. The toe cap is typically a half inch or so of rubber with an embedded steel plate, I think some multi-size ones can be found. Good luck! Q: How to count how many times a function is called I have a function that is being called from the root in NodeJS. I’d like to know how I could count how many times this function was called. I could simply save the value in the variable but then I’d have to reset it every time the function is called. Is there a way to keep the value? A: If you want to keep a count of the number of function calls without counting the number of function calls in any of the child functions (which you indicated you did not want to do) then you could create an observable object. The observable object would track the number of total function calls. This observable object’s values would then be attached to the component of interest. On component mount, the observable object is reset to zero and the function is called, the value would be updated, and then the next time component mount occurs, it would be incremented. Q: How to convert xml to spreadsheet in c#.net i want to convert xml to csv format or spreadsheet. I was using xmlstream to convert xml to xls. But i want to convert xml What’s New In? Tagging Amazon’s drones is such a commonplace event for Amazon and its fuming customers in the United States that the federal government is considering creating a list of other companies who fly drones in America. Since the Thanksgiving holiday, the Federal Aviation Administration (FAA) has investigated hundreds of complaints of Amazon drones colliding with airplanes, although the company has made no formal claim that its drones have been involved in any crashes. “We do not investigate collisions between UAS and other manned aircraft or UAS and other unmanned aircraft,” a spokesman told The Daily Telegraph. “Please refer to the FAA’s reports of these incidents.” But the FAA has also received hundreds of complaints about “suspicious” drones which have been following people or causing trouble. The FAA told The Daily Telegraph that it has spoken to Amazon about the alleged crashes. It said the collection of information, so far, has been “useful”. “We’re working with Amazon to try to resolve the situation,” the FAA spokesman said. I would just like to share that it has been settled. We successfully navigated the UAS aspect of the contract, and the “relationship” part continues. “We are disappointed that the FAA deems it necessary to enter into a “relationship” with DJI – rather than finding a resolution through the courts. We are hopeful that the FAA will continue to respect our contracts and cease the investigation, and we have no intention of interfering in DJI’s business or disrupting normal drone operations in the industry.” A statement from DJI said: “We agree with Amazon that we must maintain the existing approach to the prohibition of operations for aerial delivery. With full autonomy on a UAS, even a few simple mistakes or a mechanical issue could have catastrophic consequences. “We support the FAA, and its specialists, in achieving that goal, while acknowledging that UAS technologies are moving at a fast pace, and we continue to work toward that standard, which is why we said that it’s critical to maintain the current approach. “We certainly don’t want to pursue a path that would threaten the safety of our customers or the general public.” As many as 20 crashes involving drones have been reported in America. The most serious was last month when the craft crashed in front of a police helicopter in Pennsylvania, causing the back of the helicopter System Requirements: Windows Mac Linux Minimum: CPU: 1.2 GHz Intel Core 2 Duo RAM: 2 GB System Disk: 1 GB OPTIONAL: Multi-Core CPU DirectX 9.0c compatible video card Laptop compatible: 15.4-inch: 1280×800 14-inch: 1440×900 13-inch: 1360×768 12-inch: 1280×1024 11-inch: 1024×768 10-inch Adobe Photoshop CC 2015 Version 18 Keygen Crack Setup Free Adobe Photoshop CC 2015 Version 18 Crack + Free X64 (2022) This guide will teach you how to create very simple and quick images in Adobe Photoshop, regardless of which version you’re using. While it does not include advanced editing functions, it will teach you the basics of Photoshop and give you the tools you need to create a fantastic image. The following tools are available in all versions of Photoshop: What’s New in Photoshop CC 2017 Adobe Photoshop CC 2017 is an update to Photoshop that includes some new features to help you take your photo editing to the next level. While this article will focus on the basics of Photoshop and other offline editing tools, it will also touch upon some of the new features in Photoshop CC 2017. Shortcuts In the top-right corner of Photoshop, a few shortcuts appear: File ➤ Save and File ➤ Save for Web and Devices. These shortcuts are standard keyboard shortcuts that you can use to save the current image. Shortcuts In the top-right corner of Photoshop, a few shortcuts appear: The New Layer button on the left side of the screen will create a new layer. The New Layer button on the left side of the screen will create a new layer. The New Adjustment Layer button on the left side of the screen will add a new adjustment layer to which you can apply a new adjustment. The New Adjustment Layer button on the left side of the screen will add a new adjustment layer to which you can apply a new adjustment. The New Painting Brush and New Pencil tools appear in the top-left corner of the screen and drop down a menu of brush and pencil styles. The New Painting Brush and New Pencil tools appear in the top-left corner of the screen and drop down a menu of brush and pencil styles. To add a text box, create a new layer with the New Layer button on the left side of the screen. Tools In the top-right corner of the screen, a few tools appear: Select, you can select a portion of a layer. you can select a portion of a layer. Lasso Selection lets you select a portion of a layer. lets you select a portion of a layer. Freehand Selection lets you select a portion of a layer by drawing a boundary with your finger. lets you select a portion of a layer by drawing a boundary with your finger. Move the pointer over the tool and press and hold to activate it, and then press the arrow keys to move the tool. Adobe Photoshop CC 2015 Version 18 X64 Photoshop is a powerful imaging software and it can’t be denied that without it, almost every graphic designer and web designer can’t do his/her job. However, with its complex features, learning Photoshop is still hard. For anyone interested in photography, graphic design, web design, community management or any other jobs that require manipulating images, Photoshop is one of the most useful tools. Photoshop is a very well-known but, for beginners, it can be complicated and confusing to use. Here, we have compiled 10 of the most useful tips and tricks that every Photoshop user should know. When you’re learning Photoshop and would like to apply what you’ve learned, share your tips and tricks with others. 1. The first thing you need to do is download the free trial version of Photoshop and follow the installation guide. This guide will show you how to install Photoshop along with completing a few basic tasks in the program. 2. Next, install a new version of Photoshop or upgrade to the latest version if you are using one already. If you are ready, sign in to your Adobe ID, launch Photoshop and begin creating a new image. Click “Create a New Image” from the File menu. A dialog box will appear where you can choose the size and format for the image, select the resolution, and then add any desired settings. 3. The next thing you want to do is play around in the program and create some images. If you have Photoshop installed, you should have a number of preset templates including the text/vectors/measurements/etc. The first thing you can do is simply click on the preset template of your choice and create an image from it. Alternatively, if you don’t like the preset templates, you can create your own images from scratch by choosing the “Create a New Document” and “Create a new layer.” After creating some images, it’s a good idea to save them to your computer for future reference. To do so, click on the File menu and “Save for Web and Devices” or “Save for Web.” A drop-down menu appears where you can change the name of the document, select a target location, and choose the format. In this step, you can also choose whether or not to compress the images before you save them. 4. Also, if you want to apply these tips and tricks in Adobe Elements, you can do a681f4349e Adobe Photoshop CC 2015 Version 18 2.3.2 – What’s New in the? Q: Bridging (mesos/docker/kubernetes/zookeeper/…) on AWS I am trying to deploy a Mesos cluster on AWS. Currently, I can follow this tutorial: But it doesn’t work very well because I cannot get a Zookeeper service working. And I don’t find any documentation how to run Mesos / Docker / Kubernetes or whatever on AWS without a central server. Is there any tutorial, example or just a hint how to do this properly? A: If you want to host your container-based services on AWS, you need to run them on the EC2 instance instances. The tutorial you’re referring to talks about a central server based on Apache Mesos, but it can also be running on an EC2 instance. If you want a Mesos cluster (as you mentioned in your question), you should use Marathon instead of Mesos. Marathon is a simple wrapper for Mesos and can run in an EC2 instance. There is a tutorial for Marathon, but it is a bit old, so I’ll try to help you with a new one. As for Zookeeper, you can have several instances of it running on EC2, or maybe just one, in which case the configuration you’re using should work. I didn’t check the tutorial you linked, so it’s possible that there is a problem in the Zookeeper configuration you’re using, but this tutorial explains how you can deploy it in AWS and provides its configuration. # frozen_string_literal: true module RailsAdmin module Models module Admin module Types class Table < Admin::Types::Table include RailsAdmin::MorphTypes::AbstractionBase configurable :model, model: :table, type_options: [ System Requirements For Adobe Photoshop CC 2015 Version 18: Storage: 512 MB of memory RAM: 2 GB for optimal experience Videocard: NVIDIA GeForce GTX 680/AMD Radeon HD 7970/AMD Radeon HD 6970 Disc: DVD-R/DVD+R Music: XP SP2 / Vista SP2 Product Dimensions: 16.2 x 11.7 x 3.3 inches Weight: 4 pounds System Requirements: Adobe Photoshop 2022 (version 23) Mem Patch Keygen For (LifeTime) [April-2022] DownloadDOWNLOAD (Mirror #1) DownloadDOWNLOAD (Mirror #1) Adobe Photoshop 2022 (version 23) Crack [Win/Mac] [Updated] 2022 * To use Photoshop, you must have a personal Adobe Creative Suite product or have a software partner, such as Adobe. If you are using an older version of Photoshop, such as Photoshop CS2, you need to upgrade before you can open and edit any PSD files. I use Photoshop for the occasional photo-editing job — primarily “fixing” or “touching up” photos that I print for my website at www.jaymillerphotography.com. I use Photoshop to crop photos, remove red eye, repair color, alter a subject’s facial features, remove or add backgrounds, and also to selectively apply special effects. Adobe Photoshop 2022 (version 23) Crack+ With Serial Key Free Download Learning Photoshop CC helps you to enhance your graphic designing skills. It gives you an entry into a big world of image editing and design concepts. 11 Photoshop Programs To Increase Your Skill Level Adobe Photoshop Pro CC The Professional version of Adobe Photoshop, developed for the web and print. 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All updates are free, so upgrading to the latest version is a breeze. You don’t need to reinstall the software and lose all of your data. We are looking at the list of key features of Photoshop CC 2020. Text layers Gradient Transfer Smart Objects Mesh workspace 3D workspace 3D Layers Custom Workspaces User Interface 3D Modeling tools Artboards Crease or Curl tool 7 new Filter Layers 7 new Smart Objects Updated Brush and Pen Tools Crop Now! Honeycomb menu Publish to the Web Layer and Group Merging New Filters Paper Spaces 4K Planar Portrait Photography Custom Workspaces New Reference panel Clone Layers Invert Effect a681f4349e Adobe Photoshop 2022 (version 23) Crack+ Free Download The present invention relates to a low-pressure molding method which can be applied to molding of a polyimide, phenol, amine or the like resin, and more particularly to a low-pressure molding method which can be applied to molding of a polyimide, phenol, amine or the like resin by high-speed injection molding from a mold clamping time of several seconds to a little more than one minute. Conventional low-pressure molding methods are roughly divided into two. The first method is the so-called film molding method which is a method of molding a molded article by the use of a thin film of a resin as a pressure-receiving medium. In this method, as is well known, a mold of a shape similar to that of the molded article is first prepared, and then a thin film of a thermoplastic resin is adhered to the inner surface of the mold by such a means as thermal fusion. An article is then molded under a temperature higher than the melting point of the resin film and at a pressure lower than the pressure of the molten resin (see, for example, Japanese Patent Application Laid-Open No. 59-159766). The second method is the so-called casting method which is a method of molding a molded article using a mold which is usually at atmospheric pressure. In this method, as is well known, a thermosetting resin in an amorphous liquid state is injected into the mold at a rate lower than a settling speed of the resin in the mold and the resin is in a semi-molten state after passing through an injection gate provided in an opening of the mold. Then, the mold is closed, and the resin is immediately solidified to obtain a molded article (see, for example, Japanese Patent Application Laid-Open No. 60-175564). If the first method is applied to a polyimide molding, however, it takes more than one hour to mold a sample piece of a polyimide that is a great deal of time because a heating step is necessary. Also, the thickness of the molded article is dependent on the thickness of the thin film of resin, and the thickness of the thin film of resin is liable to be only a few tens.mu.m to a few hundred.mu.m. Thus, the film thickness is generally selected so that the molded article has an approximate thickness corresponding to the thin film. Moreover, What’s New in the Adobe Photoshop 2022 (version 23)? Q: Is there a generic factory method for creating a singleton? I was thinking about making my SingletonFactory like this : public class SingletonFactory { private static volatile T singleton; public static T getInstance() { T singletonClass = findClass().getMethod(“getInstance”).invoke(null); if(singletonClass == null) { singleton = new T(); } return singletonClass; } } This way you can have a Singleton like this : public class Singleton { public Singleton() { System.out.println(“instance”); } public static void main(String[] args) { SingletonFactory.getInstance(); } } And I didn’t see any error in it. Anyhow is there a more generic way to do this? UPDATE : removed volatile keyword because it would break the singleton concept. A: In general, a Singleton is defined for a given class as a singleton object of the class. Such an object is created the first time it is needed, and that is it – no need for using factory methods as you are providing an implementation yourself. You’re creating an object as soon as you are doing anything with it. Since you don’t have any instances, you can wrap this as a local variable as well, but this is not a Singleton. public class Singleton { public static void main(String[] args) { Singleton a = new Singleton(); Singleton b = new Singleton(); } } EDIT: Since you are using Java 8 and there is no static access modifier, there is no need to create a factory as there is no way to provide a static factory method. public class Singleton { public static void main(String[] args) { System Requirements: Multiplayer: • 4 players online • For Multiplayer only game mode, ensure that all players are connected on separate systems or through a local network. • All players must use the same device for the game. • All players must be within 20ft of each other. • Players must be able to hear and see each other. • All players will have access to the game’s scoreboard. • The game will require a minimum of 2GB of RAM. • Internet connection for all players. Adobe Photoshop 2021 (Version 22.3.1) Crack Patch Download Adobe Photoshop 2021 (Version 22.3.1) Crack + Nothing beats trial and error. There is no quicker way to find out how to use a software program than to jump right in and explore its numerous tools. Trial and error is a great way to learn a new software program as well as a way to test your abilities with a new skill. Many people find the complexity of using Photoshop intimidating, so in this chapter, I try to explain the process for using Photoshop by breaking down the various layers and components, and I even offer step-by-step tutorials to help you become more comfortable with the editing tools. Introducing the Layers You see only a portion of the layers in Photoshop. Although you can select a layer and move it, you can also add new layers above it and move them around as well. You can stack new layers on top of each other in any order, and this enables you to keep track of all the layers in your image. Think of layers as the building blocks in Photoshop. You can lay down items such as color, text, or any other object you create in Photoshop and manipulate them as one of the layers. You can, for example, create a text layer and set the text to any size, color, typeface, or just about anything you need. You can then create a background layer and place objects on top of it, or you can simply place the background layer over a photograph to make it appear as if it is a physical background. Working with Layers You can work with layers in many ways: Open a file and add a layer: You can add a new layer to an image by opening the image and choosing Layer⇒New. A dialog box prompts you to add a new layer for your new image. If you’re lucky enough to have a photo shoot of one subject on several backgrounds, you can create a layered image that you can revisit and experiment with as you need. Check out the steps for creating a new layer in this chapter and see them for yourself in this book’s “Photographing with Photoshop CS5” tutorial. Name your layers: Each layer in your image has a unique name. You can see these names in the Layers panel and even in the Layer window. In the Layers panel, Photoshop groups all the layers into sets of layers that contain the same type of object, such as figure layers that have a face on them or color layers that contain various colors. In the Layers panel, you can drag a Adobe Photoshop 2021 (Version 22.3.1) Crack [32|64bit] This tutorial will guide you through how to use Photoshop Elements. It can be used for both designing and editing images. The tutorial will cover the following: Creating a new document Creating a new layer Using the eraser tool to erase parts of the image Removing objects from the image Combining images or layers Hiding and showing objects Applying and editing different effects Changing the color of the image Using filters to transform and modify the image Adding effects to the image Shrinking and expanding the image Cropping, rotating and skew-eing the image Adding text and annotations Using textures and filters to transform the image Creating vectors Optimizing the image It is an entirely online tutorial and provides an interactive way of learning. You will learn just by watching the tutorial video and learning through the practical examples. This means you don’t have to type any code or use any icons to learn. Also, if there is something you’re stuck with or would like to learn more, just use the comments section below the video and we will try our best to help you out! This Photoshop Elements tutorial is broken down into the following sections: Creating a New Document Creating a New Layer Saving a New Document Introducing the Layer Panel Introducing the Layers Panel Creating a New Layer Shrinking and Expanding Layers Clipping Layers Revealing and Hiding Layers Making a Copy of a Layer Using the Eraser Tool to Erase Parts of the Image Removing Objects from the Image Masking an Image Combining Layers Applying and Editing Effects Creating a Color Adjustment Using a Spot Healing Brush Using a Spot Healing Brush Using the Grain Saver Using the Grain Saver Using the Clone Stamp Using the Clone Stamp Using the Gradient Tool Using the Gradient Tool Using the Drop Shadow Using the Drop Shadow Creating a Composite Creating a Composite Adding a Background Using the Gradient Tool to Fill a Selection Using the Gradient Tool to Fill a Selection Creating a Textured Layer Creating a Textured Layer Creating a Textured a681f4349e Adobe Photoshop 2021 (Version 22.3.1) Crack + [2022] The Cloner allows you to create a new copy of one area of an image. You can then use the Cloner to create copies of the area in the image. ##v What’s New In Adobe Photoshop 2021 (Version 22.3.1)? FILED NOT FOR PUBLICATION MAR 15 2012 MOLLY C. DWYER, CLERK UNITED STATES COURT OF APPEALS U.S. C O U R T OF APPE ALS FOR THE NINTH CIRCUIT OSCAR DIAZ, No. 10-55278 Plaintiff – Appellant, D.C. No. 2:08-cv-09077-CAS- JEM v. DOUGLAS WESSELS; et al., System Requirements For Adobe Photoshop 2021 (Version 22.3.1): Mac: Windows: Steam: PlayStation: Languages: Hey and welcome to my guide!It’s a 3D fantasy RPG with action elements, class-based characters and a multiplayer mode that will need you to gather your allies to play together.You can find a trailer and a lot of screenshots in my discord: Copyright 2015 The Go Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license Photoshop 2021 (Version 22.5) universal keygen Download For Windows 🔍 Photoshop 2021 (Version 22.5) Crack+ With Registration Code For Windows [Latest] ADVERTISEMENT You can download and use free Photoshop Lightroom for those who want to photograph their images in their own package. Adobe’s Senior Director of Product Marketing, Eugene Novotny, told The Global iDesign Magazine, “Lightroom is its own photo library app and [is] all about working with images. It’s a powerful tool for professional photographers and other pros and is aimed at streamlining [their] workflow and is dedicated to photographers.” New, Socialized Tools As digital photography has become more popular, photographers are creating more artful and interesting photographs than ever before. A few years ago, a photographer would have a collection of mostly glossy black and white prints that were, for the most part, indistinguishable from one another. The filters that were used were usually ones the photographer came across. Today, we have access to many more filters to apply to our images. Many manufacturers, such as Michael Muhney, have set up websites that offer additional filters. After graduating from the University of Florida in the late 1990s, Jason Lin, a graduate student majoring in architecture, decided to learn how to take better photographs. “I wanted to develop a sharper image, but [I] didn’t know how to do it,” said Lin. “One day in Photoshop I made a Photoshop preset, and I really enjoyed it.” “From there,” he said, “I was hooked.” ADVERTISEMENT “In college,” he said, “I took basic computer science classes, and I [learned] how to use Photoshop. There was one textbook that covered all of it and it was good enough that it was the one I used.” After graduating from college, Lin continued to work with Photoshop and Photoshop Lightroom. Lin said that he eventually developed quite a collection of presets, “so I started blogging to showcase my work,” and to try to help others who were interested. “I don’t try to hide my presets from you,” Lin told us. “I am very open about my process and I want others to be able to replicate the effect.” Lin uses a number of presets when he shoots because he believes that he has an advantage when he uses presets. “Each preset uses a different color scheme and either a light or a dark color scheme,” he said. “Having the color schemes in your palette makes it easy to compare the presets and choose the best choice for your Photoshop 2021 (Version 22.5) Crack+ License Key Full Free Adobe Photoshop is the most powerful desktop image editor. It’s also costly, costing around$99 USD per license for a standard license.
Adobe Photoshop Pro is a more expensive alternative to Photoshop Elements. It provides most of the feature of Photoshop and its text tool has been upgraded.
If you don’t have the money to spend on a new copy of Photoshop, you can use Adobe Photoshop Mix. Mix allows you to use features of Photoshop on a non-commercial basis. Mix is a free, open source alternative.
In this article, we’ll show you what you can do with Photoshop Elements, especially for beginners. We’ll walk through the interface and show you how to edit and fix images. We’ll explain how to create new ones too. Along the way, we’ll discuss how to use “open software” to customize it even more. We’ll show you how to use Mix too.
What can Photoshop Elements do?
This image editing app can do everything that Photoshop can. Not only can it edit and resize images, but it can also apply effects, create and edit images, fix images, and even make up new designs for you.
The “Open Image” menu allows you to add other images, create new ones or open and view them. Here, you can view the editing tools and tools to edit images on a timeline.
Other menus allow you to change the color and size of images, adjust the hue, and create new images.
Adobe Photoshop Elements helps to the design of logos, websites and posters. It’s also a great image editing tool to modify and create new images.
How to use Photoshop Elements
For image editing, use the Import and Open dialogs. Both of these allow you to change the brightness, contrast, saturation and color of images. You can also crop and resize images.
Using these two dialogs will enable you to change the color and tone of images. You can also select images and set them to a different size.
You can also use the tools on the timeline. You can slide them across the image to make changes. This means you can change the brightness of the image and make adjustments as needed.
Tips for Photoshop Elements
There are many ways you can use Photoshop Elements to edit images. But here, we’ll show you the ways we use it
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6. Select the Brush tool from the Tools toolbar and adjust the size of the brush by clicking the dial control next to the Brush Size text box.
7. Click and drag the Brush control on the right side of the dialog box. This allows you to adjust the opacity, softness, and size of the brush.
8. If necessary, click the image to set the foreground and background colors of the brush in the Brush controls box.
9. Make a selection in the image you will be working on.
10. Click the Clone Stamp button located on the bottom left of the dialog box.
11. A new selection of the image is created in the area where you clicked the Clone Stamp button, and the Brush tool will start to copy the selected pixels. You can stop this by clicking the Clear button in the upper-right of the dialog box.
* * *
# Guided Brush Tutorial
Create the following image using our tutorial on using brushes.
1. Draw the rectangle as shown in the illustration and select the foreground and background colors of the brush. You can adjust the Softness and Size settings in the Brush dialog box.
2. Use the circular brush to retouch the background to adjust the appearance of the image.
3. Create a new layer and change the foreground and background colors to any color you like.
4. Select the water-color brush and set the foreground color to the color you want to paint the water with. Adjust the settings in the Brush dialog box.
5. Select the Burn tool from the Tools palette and create a new layer. Be sure to set the blending mode of the layer to Overlay. Set the Opacity of the layer to 30%.
6. Use the Burn tool to burn into the layer. Watch the Effect controls in the dialog box. We suggest that you experiment with the color, hardness, and brush size to get the desired look.
7. Use the Lasso tool to select the sky and earth layer. Using the Polygonal Lasso Tool, select the buildings. Burn the objects into the sky and earth layer.
8. Make sure that the Burn mode is set to None.
9. Select the Brush tool from the Tools toolbar. Create a new layer. Use a larger brush and set the brush color to a color close to the sky color. You can adjust the settings in the Brush dialog box.
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What’s New In?
Intentional poisoning and non-intentional poisoning of domestic cats in Japan: a retrospective study of 618 cases (2009-2014).
Case records of 618 cats that presented to veterinary clinics in Japan between 2009 and 2014 were retrospectively reviewed to analyse intentional and unintentional poisoning cases. Intentional cases represented approximately 8% (n = 51) of the entire cat population. The most common method of poisoning was via drinking water. Alcohol, anticoagulants and fish liver oil were most frequently identified as causes of poisoning in intentional cases. Unintentional cases represented approximately 92% (n = 567) of the total cat population; the most common methods of poisoning were via food, cat litter and plant pesticide ingestion. Main causes of poisoning were unknown substances (n = 214) or a pesticide (n = 151). Both intentional and unintentional poisoning resulted in significantly lower body weights than control cats (p I am overwhelmed by the wonderful wish you have expressed in your last post and the stunning photography you sent. I immediately thought of my sister, Nancy, who is a wonderful and smart art historian. And then I realized that I must have brought this up to you before, but never got it across the way I wanted to.
At some point in the course of her careers as an artist, my sister Nancy had to give up her beloved painting of Paris. She had to give up all her studio equipment, including the means to do artwork of any sort. From her home in Paris, she did a few paintings of the city and the surrounding area, but her art history classes began to steal her life, and she had to drop out of her art history master’s program.
An eerie thing happened. Instead of spending a couple of years returning to the Parisian studio to paint, she began to paint from life.
No, she didn’t move to an exotic locale and paint from there. She moved to her studio in the apartment above her studio in Paris, and painted from life in that room. And some of the results are amazing. She began to paint the Paris shops in her own unique style, and she continues that today.
No, she didn’t sign her painting. She gave the paintings a number, and gave her catalog number as the sales price. She’s never sold her paintings.
She, I have no doubt, collects art. Her collection is not on display. She keeps it all in her apartment in Paris. It’s locked up
System Requirements:
Processor: Intel Core i5 2.6 GHz
RAM: 4GB
OS: Windows XP, Vista, Windows 7, Windows 8, Windows 10 (32-bit or 64-bit)
Hard Drive: 15GB
Graphics: 2GB GeForce GTX 460
DirectX: Version 9.0c
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# Neutrino 2020
June 22, 2020 to July 2, 2020
US/Central timezone
## Sensitivity of the LUX-ZEPLIN experiment to the 0νββ decay of Xe-136
Not scheduled
10m
Poster
### Speaker
Claudio Frederico Pascoal da Silva (LIP-Coimbra)
### Description
The LUX-ZEPLIN (LZ) experiment is a 7-tonne liquid xenon time projection chamber primarily designed to search for dark matter particles in the form of weakly interacting massive particles. Nonetheless, we can take advantage of the significant ${}^{136}$Xe mass (>600 kg) present in the active volume of the detector to look for neutrinoless double beta decay of that isotope. We report the projected LZ sensitivity to this decay after 1000 live-days without isotopic enrichment (half-life>$1.06\times 10^{26}$ years, 90% CL) and with a 90% isotopic enrichment with ${}^{136}$Xe (half-life>$1.06×10^{27}$ years, 90% CL). This result makes use of a profile likelihood ratio (PLR) method and includes updated background models, namely from the cavern walls, from the solar neutrinos, and neutron capture on ${}^{136}$Xe.
### Mini-abstract
A new result for the sensitivity of the LUX-ZEPLIN detector to the 0νββ decay of Xe-136.
Experiment/Collaboration LUX-ZEPLIN
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# Section 4.5: Analysis
This section seems to be a quick abstract way to explain how one can tell whether or not a given polynomial is reducible in either $\mathbb{Q}$ or $\mathbb{Z}$. Hungerford starts with the Rational Root Test and later Eisenstein’s Criterion. This entire section is limited to $\mathbb{Q}$ and $\mathbb{Z}$, I wonder if there exists similar tests that are valid for other fields ($\mathbb{Z}$ is not a field but $\mathbb{Q}$ is). Yet, part of the power of what has been done so far comes from understanding how the basics of the areas of mathematics that have been taught to each of us since an early age (addition, division, multiplication etc). Whether or not there are similar tests won’t matter if the basics aren’t understood.
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But in worst case it is O(n^2) then also it is better than other sorting algorithms which exhibit O(n^2) time complexity. Then the algorithm recursively does the same for the left and right portions of the array. If you'd like to read a detailed, dedicated article for Insertion Sort, we've got you covered! So, Counting Sort is an Integer-based algorithm that means the numbers or the values of the input received from the user must be or assumed to be integers like in bucket sort and radix sort algorithm. I hope you enjoyed this tutorial. In fact, Java 7 has internally used merge sort to implement the Collections.sort method. It judges algorithm as fastest that reduces move count at the sacrifice of the comparison count. If we solve this recursion equation we will get O(nlogn). To sort them, we further divide them into their components. Now we call again quick sort algorithm on left sub array. JavaScript is taking over the world as the language of the web. In computer science, a sorting algorithm is an algorithm that puts elements of a list in a certain order.The most frequently used orders are numerical order and lexicographical order.Efficient sorting is important for optimizing the efficiency of other algorithms (such as search and merge algorithms) that require input data to be in sorted lists. Though, this time, the sorted subarray is formed by inserting the minimum element of the unsorted subarray at the end of the sorted array, by swapping: In each iteration, we assume that the first unsorted element is the minimum and iterate through the rest to see if there's a smaller element. It has taken all advantages of merge sort and it has overcome the disadvantage of using auxiliary space also. An almost complete binary tree of depth d has a subtree of depth d-1 with the same root that is complete, and in which each node with a left descendent has a complete left subtree. It is also called partition exchange sort. 3 5 7 x 8 2 1 9 6: Where the value of x is not of crucial importance, since it will be overwritten immediately (either by 4 if it's its appropriate place or by 7 if we shift). Of course, there is no one answer. After copying, we go through the resulting array and assign it the current minimum. Pivot and the element present at right index should be swapped. While this abstraction is welcome and necessary for effective work, it can sometimes be deadly for efficiency, and it's good to know how to implement various algorithms and be familiar with their pros and cons, as well as how to easily access built-in implementations. To do this, your class must implement the Comparable interface, where T is your type, and override a method called .compareTo(). Each of those n times we're iterating through the whole array (for-loop in the code), meaning the worst case time complexity would be O(n^2). 6 5 8 3 1 2 4: Because 8 > 6, we swap them. //swap the elements so that small element will come to correct position. A sorting algorithm is an algorithm that puts elements of a list in a certain order. Conversely, for the kth element the parent's position is always (k-1)/2. Step 7: the base condition for quick sort is same as merge sort. If you have your own types, it may get cumbersome implementing a separate sorting algorithm for each one. However, there is always the trade-off of having to require a bit of additional space to store the elements. If you'd like to read a detailed, dedicated article for Bubble Sort, we've got you covered! Quicksort is another Divide and Conquer algorithm. This allows me to build prototypes and test code segments quicker. It is division part. In this post, let’s explore the possibility of sorting faster in JavaScript. In addition, the algorithm is extremely easy to parallelize, since recursive calls from one node can be run completely independently from separate branches. In fact, the smaller the array, the faster insertion sort is compared to any other sorting algorithm. It is used in many bundled libraries and APIs. Means all elements were placed right now right index position will be the pivot position. We'll be analyzing their time complexity in order to compare them and see which ones perform the best. 1. Sortbenchmark.org runs a yearly sorting competition. One trick I do to reduce the risk of hitting a really bad case there is that I skip over common prefixes. This may sound bad, as we have already learned multiple algorithms which run in O(nlog n) time as their worst case, but Quicksort is actually very widely used. What is the fastest sorting algorithm known to man? It is a stable sort, so the relative position of the elements are preserved. This sort() method takes the collection to be sorted as the parameter and returns a Collection sorted in the Ascending Order by default. In this activity, we will write an algorithm in Java to sort an array using merge sort. you draw card either put in a new pile or existing pile. This algorithm is implemented in Java’s Arrays.sort() as well as Python’s sorted() and sort(). Which sorting algorithm is the fastest? The rest of the equation is complexity of merging all of those solutions into one at the end. The best case time complexity for this algorithm is O(log log N) but in the worst case, i.e. 11 8 5 4 3 2 1 9 Merge sorting is one of the fastest sorting techniques. Quicksort is considered to be one of the fastest sorting algorithms. That means our complexity is O(nlog n). When it comes to sorting, JavaScript is about 9 times slower than C++ and C#, but is slightly faster than Python 3.6, as I’ve shown in the previous post Sorting Speed of Several Languages. By repeating this process, until no more swaps are made, we'll have a sorted array. Answer: Merge Sort is supposed to be the fastest sorting algorithm in Java. We recursively heapify for 5 now. This is an extremely good time complexity for a sorting algorithm, since it has been proven that an array can't be sorted any faster than O(nlog n). Program: Implement quick sort in java. Consider the following example: In the first iteration, 5 will "bubble up to the surface," but the rest of the elements would stay in descending order. We want to sort them primarily by generations, but also secondarily by IDs: And here's how to use it in an application: We might want to sort our objects in an unorthodox way for a specific purpose, but we don't want to implement that as the default behavior of our class, or we might be sorting a collection of an built-in type in a non-default way. Step 2: it will maintain two indexes one from left side and one form right side. In this equation, a tells us how many times we call the recursion, and b tells us into how many parts our problem is divided. As name suggested it is one of the fastest algorithms with average time complexity O(nlogn). It is popular because it is faster and also space efficient. If this happens in every pass then it will exhibit the worst case. A stable sorting algorithm is an algorithm where the elements with the same values appear in the same order in the sorted output as they appear in the input list. So you follow the down arrow to the bottom of the tree, and then go back up and merge. So, i am just wondering how Oracle decides which algorithm to use. 4 Ways to Check String is Anagram in Java, Upload File to Server Using Servlet Example. If T(n) is runtime of the algorithm when sorting an array of the length n, Merge Sort would run twice for arrays that are half the length of the original array. It has a time complexity of Θ(n log(n)) on the average.However, in the (very rare) worst case quicksort is as slow as Bubblesort, namely in Θ(n 2).There are sorting algorithms with a time complexity of O(n log(n)) even in the worst case, e.g. Heapsort is an in-place sort, meaning it takes O(1) additional space, as opposed to Merge Sort, but it has some drawbacks as well, such as being difficult to parallelize. Comment document.getElementById("comment").setAttribute( "id", "a1bf8209b312764ad1d4dcea36283911" );document.getElementById("bda62a1fb0").setAttribute( "id", "comment" ); Save my name, email, and website in this browser for the next time I comment. When you think about what Bubble Sort is doing, like previously discussed, it is fairly easy to see why this isn't the best way to sort a list. Indra Budiantho wrote: As further as i know, ordering is a bottleneck for performance. Approach: An ArrayList can be Sorted by using the sort() method of the Collections Class in Java. That's why Java provides an interface allowing you to use Collections.sort() on your own classes. Submitted by Abhishek Kataria, on June 29, 2018 . Quicksort is one of the fastest sorting algorithms for sorting large data. It is quite slow at larger lists, but very fast with small lists. Step 1: it will choose an element as pivot element. The concept behind Insertion Sortdivides the range into the subarrays that are sorted and unsorted. To properly understand why Heapsort works, you must first understand the structure it's based on - the heap. We swap the root of the heap with the end of the array, and shorten the array by one. Merge Sort already doesn't work in-place because of the merge step, and this would only serve to worsen its memory efficiency. T(n) = \Bigg\{ Comment below if you doubts related to above program for quick sort in Java. This guarantees that the pivot is in its proper place after the process. Let's run all of the implementations, one by one, each on a copy of a shuffled array of 10,000 integers: We can evidently see that Bubble Sort is the worst when it comes to performance. Again 2 is taken as pivot element in the left sub array. Leaves have no children, so they're trivially max-heaps of their own: 6 1 8 3 5 2 4: Both children are smaller than the parent, so everything stays the same. Avoid using it in production if you can't guarantee that it'll handle only small collections and it won't stall the application. In this article, we will learn about the basic concept of external merge sorting.Example of external merge sorting with their algorithm. And after crossing left and right indexes we should swap our pivot element with right index.eval(ez_write_tag([[336,280],'thejavaprogrammer_com-medrectangle-4','ezslot_2',106,'0','0'])); Now our list is divided into two sub arrays. It also provide metadata of each algorithm which provide some basic data like no of iterations, no of swapping operations, time taken by algorithm to sort or search elements. Merge Sort uses recursion to solve the problem of sorting more efficiently than algorithms previously presented, and in particular it uses a divide and conquer approach. When I get the program working, I go back and change it to a quicker sorting algorithm. It is also considered to be the best sorting algorithm. The record for fastest sort is currently 0.582 TB/min. First it will start search from left side for greater element than pivot then we will stop incrementing left index. First we will see how partition is going on by taking one element as pivot. In fact, Java 7 has internally used merge sort to implement the Collections.sort method. To figure out time complexity of Bubble Sort, we need to look at the worst possible scenario. such strings, or roughly 4.03*10 26 strings, there are few duplicate strings in our sample data sets. We have to do this for each element in every array, which means it's going to be bounded by O(n^2). For example, let's take our Student class, and sort only by ID: If we replace the sort call in main with the following: Collection.sort() works by calling the underlying Arrays.sort() method, while the sorting itself uses Insertion Sort for arrays shorter than 47, and Quicksort for the rest. Unsubscribe at any time. Quick sort has been said to be fastest. This process repeats from the beginning of the array until all elements are in order. For this, we can use the Comparator interface. Similor to merge sort, Quicksort works on the divide and conquer algorithm. We find out by attempting to find an O(n) time complexity sorting algorithm. Sorting Algorithms: Slowest to Fastest! Such type of sorting is known as External Sorting. That all being said, it's often useful to run all of these algorithms on your machine a few times to get an idea of how they perform. Quicksort is one of the most efficient ways of sorting elements in computer systems. when the elements are not uniformly distributed, it is comparable to linear search time complexity which is O(N). ... Quicksort is one of the fastest sorting algorithms for sorting large data. In right sub array 5 is first element so 5 will be pivot. It has taken all advantages of merge sort and it has overcome the disadvantage of using auxiliary space also. The most-used orders are numerical order and lexicographical order. Given there are n! After this process, the sorted portion was expanded by one element, we now have five rather than four elements. The reason is that the first three passes over the data are very fast in this case because all elements have the same value for the first three bytes. But regarding the measurement time as algorithm performance includes a trap. The algorithms are implement using java generic … It was implemented by Tim Peters in 2002 for use in the Python programming language and now used in java Arrays.sort() as well. Syntax: public static void sort(int[] arr, int from_Index, int to_Index) arr - the array to be sorted from_Index - the index of the first element, inclusive, to be sorted to_Index - the index of the last element, exclusive, to be sorted This method doesn't return any value.. A Java program to sort an array of integers in ascending order. There is no algorithm that has all of these properties, and so the choice of sorting algorithm depends on the application. In our example, we've made a class Student, and each student is identified by an id and a year they started their studies. And as the time complexity is the biggest thing that should be kept in the mind, so we always preferred quicksort in many cases among any other sorting algorithm. The time complexity of Quicksort is O (n log n) in the best case, O (n log n) in the average case, and O (n^2) in the worst case. $$. Timsort is a fast sorting algorithm working at stable O(N log(N)) complexity. Rather than spend a large amount of time getting a more complex sorting algorithm to work with my data, I code up Bubble Sort quickly and continue working on more pertinent sections of a program. eval(ez_write_tag([[300,250],'thejavaprogrammer_com-banner-1','ezslot_6',108,'0','0'])); Now again sub array also divided further again recursive call will done on remaining sub array. The smaller parts are sorted using Insertion Sort and are later merged together using Mergesort. Answer: Merge Sort is supposed to be the fastest sorting algorithm in Java. It is also using divide and conquer strategy to sort as like merge sort. When we look at the heapify() function, everything seems to be done in O(1), but then there's that pesky recursive call. If pivot element divides array into two equal halves then it will exhibit good performance then its recursive function is: O(n) is for partitioning. Here you will learn about quick sort in Java with program example. Quicksort is a sorting algorithm, which is leveraging the divide-and-conquer principle. Quick Sort Algorithm. Which sorting algorithm is the fastest?Ask this question to any group of programmers and you’ll get an animated discussion.Of course, there is no one answer.It depends not only on the algorithm, but also on the computer, data, and implementation.However, if you count the number of operations needed to sort integer numberson a standard von Neumann computer, there is a clear winner –the algorithm presented in the paper“Sortin… Java Sorting Algorithms. Space Complexity. \end{matrix} Because at least one swap occurred during the first pass (there were actually three), we need to go through the whole array again and repeat the same process. //means before ith index all elements should be less than pivot. The merge step takes O(n) memory, so k=1. This is because it has a really good average runtime, also bounded by O(nlog n), and is very efficient for a large portion of possible inputs. There have been various variants proposed to boost its performance. When implemented well, it can be about two or three times faster than its main competitors, merge sort and heapsort. This fast average runtime is another reason for quicksort's practical dominance over other sorting algorithms. By Darinka Zobenica • 0 Comments. First, we decide a pivot element. Step 5: Again continue the same procedure until left index and right index cross each other means right index should be lesser than left index. While we won't be getting into how and why, as it's beyond the scope of this article, it's worth to keep in mind the pros of using this particular algorithm. In computer science, a sorting algorithm is an algorithm that puts elements of a list in a certain order.The most frequently used orders are numerical order and lexicographical order.Efficient sorting is important for optimizing the efficiency of other algorithms (such as search and merge algorithms) that require input data to be in sorted lists. With over 275+ pages, you'll learn the ins and outs of visualizing data in Python with popular libraries like Matplotlib, Seaborn, Bokeh, and more. What is the fastest algorithm to sort them assuming that X, Y, and N will be known at run-time and may be passed as parameters into the algorithm? Because heapSort() is clearly O(n) due to for-loops iterating through the entire array, this would make the total complexity of Heapsort O(nlog n). It will devide until sub array length is 1. 2 1 4 5 3: These two are in the right order, 4 < 5, so we leave them alone. It is also using divide and conquer strategy to sort as like merge sort. One of the reasons it is preferred to Merge Sort is that it doesn't take any extra space, all of the sorting is done in-place, and there's no expensive allocation and deallocation calls. External sorting, radix sorting, string sorting, and linked list sorting… For non-recursive algorithms, we could usually write the precise time complexity as some sort of an equation, and then we use Big-O Notation to sort them into classes of similarly-behaving algorithms. The equation would then look like this:$$ In this post I will talk about another sorting algorithm, the Merge Sort Algorithm, which is considered to be the fastest sorting technique by many. The project implements sorting algorithm and search algorithms in java. eval(ez_write_tag([[300,250],'thejavaprogrammer_com-large-leaderboard-2','ezslot_7',109,'0','0'])); Here entire left sub array of original problem is solved so it will call recursively on right sub array. Or else we will increment that left index. It is useful only for small data sets. 6 5 8 3 1 2 4: Both of the children are smaller, so nothing happens. Expand this to any array of n elements, and that means you need to do n iterations. 4. The answer, as is often the case for such questions, is "it depends". Java is an object-oriented programming language, so it allows you to write sorting algorithms as classes and implement them easily using sorter objects. 9: Radix Sort: In Radix sort, the sorting is done as we do sort the names according to their alphabetical order. The list of algorithms you'll learn here is by no means exhaustive, but we have compiled some of the most common and most efficient ones to help you get started: Note: This article will not be dealing with concurrent sorting, since it's meant for beginners. Only the last pass actually has to do anything. If you're interested in how sorting works, we'll cover various algorithms, from inefficient but intuitive solutions, to efficient algorithms which are actually implemented in Java and other languages. The logic of our tree of recursion otherwise stays the same, though, we just have to follow the indexes we're using: To merge the sorted subarrays into one, we'll need to calculate the length of each and make temporary arrays to copy them into, so we could freely change our main array. We do this by moving all the elements to the right … Get occassional tutorials, guides, and reviews in your inbox. We would have to do one iteration for each element except 1, and then another iteration to check that everything is in order, so a total of 5 iterations. We'll be talking in terms of a binary heap specifically, but you can generalize most of this to other heap structures as well. However, being an O(n 2) algorithm, it becomes very slow very quick when the size of the array increases. This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. Since 8 > 4, we shift. Now we are going to the outer loop which we could use the variable i if we want to try this up**. This is recursive process until sub array length is ‘1’. It picks one element of an array as the pivot and sorts all of the other elements around it, for example smaller elements to the left, and larger to the right. The insertion sort is not a fast sorting algorithm because it uses nested loops to shift items into place. If the heap is a max-heap, then all of the children are smaller than the parent, and if it's a min-heap all of them are larger. Step 3: From right side we will search for lesser element than pivot. Hello people…! Look at elements one by one 2. Elements which are present in the left side of pivot are one sub array and elements which are present at right side pivot is one array. The input list is divided into two sub-lists by an element called pivot; one su… At the end all values will get sorted. 2 1 4 3 5: Here's the resulting array after one iteration. 6 1 8 3 5 2 4: Because 5 > 1, we swap them. But because it has the best performance in the average case for most inputs, Quicksort is generally considered the “fastest” sorting algorithm. All numbers move to their respective places bit by bit, left to right, like bubbles slowly rising from a body of water. Conclusions. Insertion sort. This method returns a negative integer if this is smaller than the argument element, 0 if they're equal, and a positive integer if this is greater. 1 2 3 4 5 8 9 11. We iterate through the array and during each iteration, we expand the sorted portion of the array by one element. Basic quick sort example is shown in {message:id=10199271}. For example, if in the following array the bolded part is sorted in an ascending order, the following happens: 3 5 7 8 4 2 1 9 6: We take 4 and remember that that's what we need to insert. Q #3) What is Bubble sort in Java? We do this by shifting all of the elements to the right until we encounter the first element we don't have to shift. Build the foundation you'll need to provision, deploy, and run Node.js applications in the AWS cloud. External Sort-Merge Algorithm. Conclusions. Now we got an idea how quick sort is working. Looking at the code, that would mean that our while loop can run the maximum of n times. Timsort is a blend of Insertion Sort and Mergesort. When we expand, we position the fresh element in the sorted sub-array. A sorting algorithm is an algorithm that puts elements of a list in a certain order. Quicksort algorithm is one of the fastest internal sorting algorithms and today we are going to discuss this topic. External sorting is a technique in which the data is stored on the secondary memory, in which part by part data is loaded into the main memory and then sorting can be done over there. As name suggested it is one of the fastest algorithms with average time complexity O (nlogn). Required fields are marked *. Merge sort is best suited for sorting Linked Lists. It was used in the tests with arrays of size 100. We move through the array and expand the classified part of the array by one component during every iteration. We're going to implement Bubble Sort in a similar way we've laid it out in words. About quick sort : Quicksort (sometimes called partition-exchange sort) is an O(n log n) efficient sorting algorithm, serving as a systematic method for placing the elements of a random access file or an array in order.Developed by British computer scientist Tony Hoare in 1959 and published in 1961, it is still a commonly used algorithm for sorting. Timsort: A very fast, O(n log n), is a hybrid stable sorting algorithm. You can even define your own criteria, and we'll go into practical ways of doing that by the end of this article. Insertion is the most basic sorting algorithm which works quickly on small and sorted … Sorting is endorsed by several languages and often the interfaces obscure what the programmer does. Quick Sort is also another best sorting algorithm. By Java is highly versatile and known for its fast performance, security, and high reliability. \begin{matrix} Which can be used in PL/SQL for sorting PL/SQL arrays - instead of pushing the array and its contents to the SQL engine to sort and then pulling the sorted data back from the SQL engine into a new PL/SQL array. For each element, check if any of its children are smaller than it. If you'd like to read a detailed, dedicated article for Merge Sort, we've got you covered! The idea behind Insertion Sort is dividing the array into the sorted and unsorted subarrays. Build up sorted list by inserting the element at the correct location Here’s a trace table showing how insertion sort would sort the list [34, 10, 64, 51, 32, 21] In this instance we are inserting the newly sorted … Hence its space complexity is O(1). This algorithm also requires only one unit of space to store the element to be searched. A Hybrid Algorithm is an algorithm that combines two or more other algorithms that solve the same problem, either choosing one (depending on the data), or switching between them over the course of the algorithm. The fastest sorting algorithm? It will do that by jumping to the parent of each node, so around the position i/2. They'll perform differently with different collections that are being sorted of course, but even with that in mind, you should be able to notice some trends. How many times will that be called, in the worst case scenario? The Master Theorem is used to figure out time complexity of recursive algorithms. In fact the opposite happens: My algorithm is fastest in these cases. We can take first element as pivot element or last element, randomized element, middle element, etc. While the version we've showcased is memory-consuming, there are more complex versions of Merge Sort that take up only O(1) space. We will swap them now.eval(ez_write_tag([[580,400],'thejavaprogrammer_com-medrectangle-3','ezslot_1',105,'0','0'])); Again same procedure will be continued until left and right indexes cross each other. We know that all elements are in order when we manage to do the whole iteration without swapping at all - then all elements we compared were in the desired order with their adjacent elements, and by extension, the whole array. Fast sorting is the fastest sorting algorithm in the average Time. This is because in each iteration, we'll have to move the whole sorted list by one, which is O(n). Since 7 > 4, we shift. Your email address will not be published. In practical performance, randomized quicksort is often the real winner, despite also being O(n^2) worst case, but that's not really about asymptotic performance. Using both of these concepts, we'll break the whole array down into two subarrays and then: This tree is meant to represent how the recursive calls work. We'll define the following int arrays in a @BeforejUnit method: The core function works pretty much as laid out in the explanation. patience sorting: sorting based on solitaire card game. Throughout this chapter, we have demonstrated performance of sorting algorithms when sorting 26-character strings that are permutations of the letters in the alphabet. Timsort first analyses the list it is trying to sort and … According to that again right sub array will be partitioned. Quick Sort performance entirely based upon how we are choosing pivot element. Introduction. An insertion sort is a simple sort which is most effective on small lists. +1 for several points, but I don't see how bubble sort can be considered asymptotically as fast as mergesort or heapsort, both of which are worst case O(n log n), whereas bubblesort is worst case O(n^2). Quick Sort is also another best sorting algorithm. Important: Use the pseudocode shown in Snippet 2.11 and Snippet 2.12 to implement the full merge sort algorithm in Java. O(n^{log_ba}), & a>b^k \\ O(n^klog n), & a = b^k \\ O(n^k), & a < b^k You can use various ordering criteria, common ones being sorting numbers from least to greatest or vice-versa, or sorting strings lexicographically. . Note: The time complexity would always be O(n^2) if it weren't for the sorted boolean check, which terminates the algorithm if there aren't any swaps within the inner loop - which means that the array is sorted. Suppose in one pass we have taken largest element then it will divide n length array into n-1 elements one side ‘0’ . Scenario: Merge sorting is one of the fastest sorting techniques.
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Can someone explain to me what the phrase "Everything moves through space-time at the same speed" means? [duplicate]
It's a statement I've seen thrown around here and there. Essentially, under relativity, everything can be said to move at c, some part of it is motion through space, some of it through time, and when we speed up or slow down we are merely exchanging one motion for another. However, I never understood what is meant by "speed" or "motion" here.
Specifically what confuses me is the idea of "motion through time". "Speed" to me normally means the rate in which an object varies in space over time, and to talk about something "moving" we talk about it changing it's position with respect to time. But what does it mean when we say that an object "moves" through time (or space-time) or has a "speed"? Speed with respect to what? And what would it mean for something to move through spacetime at a different rate?
Right now, the only way I can make sense of the idea of a speed through spacetime is by introducing some sort of meta-time or hypertime, with which we can talk about movement through space-time, but that sounds a bit extreme. Can someone help explain it for me? Hope this all sounds clear enough for you guys. Thank you in advance.
• Possible duplicate of Why are objects at rest in motion through spacetime at the speed of light?
– Styg
Dec 10 '17 at 14:33
• @Samarth, I don't think my question is the same as the one you linked as the person in that question seems to be asking why the speed through spacetime is a particular value, while I am asking what it even means to talk about a speed through spacetime. Apart from that, some of the answers do seem relevant to my question, so I'll check them out. From the looks of it, it seems like some of them state that the description of "movement through time" or having a "speed through spacetime" is inaccurate, is that right?
– Mike
Dec 10 '17 at 15:05
• Define speed. Otherwise one might take it to be dx/dt. Dec 10 '17 at 15:11
• @jjack, well, that's the whole the point of my question. I don't know what it even means when we talk about an object having a "speed" through space-time and I want to ask you guys about it.
– Mike
Dec 10 '17 at 15:21
• @Mike I'm someone who would define a distance measure on spacetime with respect to the Big Bang. But on this site I've heard that all spacetime models are defined as differentiable manifolds without origin, so there is no Big Bang event in them. I would however take the derivative with respect to that metric (relative to the Big Bang event) of position in spacetime and define this as velocity in spacetime. But then, I've recently heard, that there are physicists who question the "past" existence of a Big Bang. However I haven't read anything about those people's research yet. Dec 10 '17 at 15:36
Suppose an object moves at $\beta$ times the speed of light in your reference frame. Then in an infinitesimal time $dt$ you see the object move a distance $c\beta dt$, so $$ds^2:=c^2dt^2-d\mathbf{x}^2=c^2(1-\beta^2)dt^2=c^2d\tau^2,$$ with proper time $\tau:=\int\sqrt{1-\beta^2}dt$. The "speed through spacetime" is $ds/d\tau=c$. Equivalently, our distance-to-time measure can be $\dfrac{\sqrt{ds^2+d\mathbf{x}^2}}{dt}=c$.
You must understand that time just another spatial coordinate in relativity. Even if two protons have zero relative velocity, and even for an external observer, they still move along the time axis with the speed of light. From this point of view, everything moves along the time axis with the same speed, c. This is why you have time multiplied by the speed of light as a coordinate in the definition of distance in general relativity. And this is why you'll always have the mass-energy formula for objects with rest mass. I can give you an example of motion along the time axis: whenever a particle suffers a change in it's state, that is an evolution along the time axis. If anything describes evolution along the time axis, that is change itself and also entropy when speaking of more complex systems. How can we have a speed along the time axis? Well, some systems undergo faster transitions, some systems do that slower or even faster, so yes, there is a speed along the time axis. It is the rate of changes happening when compared to another system. Objects do not move only in the 3D system, they also move in their internal phase space which gives them what is called the proper time.
If I can relate change to a variable, then that change is a motion along the axis of that variable. It is mathematically correct. However, we both agree that time emerges from change, but try not to remain so enclosed in these definitions. If you'll accept change as being a motion, you'll make a big step ahead. It is called abstractization. Motion is not only something happening along x,y,z. It happens in lots of kinds of spaces. And if time is seen as an ordered set of changes, then a system undergoing changes is basically evolving along that set of changes. For example let's take a completely isolated system which has only two states: A and B. And it cycles continuously discretely between A and B. It's time axis has only two points A and B. Other temporal subdivisions simply do not exist since there is no change behaving as a superposition of A and B. Hence, his evolution or change is a motion along his proper time axis AB.
• I'm not sure if time is exactly like space, but I can grant that it functions much like space does. I can try imagining that motion through time is just like motion through a 4th spatial dimension, but like I said in my OP, in order to even make sense of such motion it seems like we need to introduce another time dimension with which this "motion" occurs. Also, your example seems to describe a change within time, rather than any motion. Sure some particles can undergo processes faster or slower than others but to even speak of such speeds requires that we talk about them with respect to time.
– Mike
Dec 10 '17 at 15:15
• Aaaa...yeah, time is viewed as a component of the 4D space. I can understand your problem, I had it too once. The notion of speed is seen in mathematics usually as the rate of change of any type of variable and not necessarily as a movement through space. In general relativity we must however use clocks to make observations. You can not determine your own speed along the time axis without comparing it to an external clock or reference. My example says that change is what determines motion along time, hence it determines what we call time. I just gave you the way time emerges. Dec 10 '17 at 15:30
• This issue becomes important in cosmology when it seems that time can not be used anymore, becoming seemingly inexistent for an external observer, so instead of the time coordinate, they use another type of axis to define time, and that axis is in fact the history of the evolution of the Universe. Also in rotating black-holes, time and space exchange places. Dec 10 '17 at 15:40
• Yeah, I can agree change determines or defines time, however I wouldn't say that change is a "motion" through time. To me, time is emergent from change just as space is emergent from the concept of distance.
– Mike
Dec 10 '17 at 16:10
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# Use of \afterpage package causes equation to be inserted into following subequations
I have a very long equation, which cannot be split apart, which I place on a landscape page on its own.
However, when I compile the document, this equation now seems to have been placed inside the subequations environment of two equations further down the text. This leaves me with incorrect numbering. The landscape equation should be equation 1, the next two should be 2 a,b. At the moment I get the landscape equation labelled as 1b, with the two later equations written as 1 a,c.
If I reduce the text above the equation, so move the position on the page, the numbering returns to normal. However, I can't unfortunately just delete paragraphs of text...
MWE follows. (The lipsum and seemingly random lines are required to get the equations and text in the right part of the page to see this problem.)
\documentclass[12pt]{ociamthesis}
\usepackage{amsmath, pdflscape,afterpage,hyperref,lipsum}
\begin{document}
\lipsum[1-3]
The long equation is first referenced here. \par
\vspace*{\fill}
\afterpage{
\clearpage
\begin{landscape}
\vspace*{\fill}
$$\label{sf:1} y = {a \over b} .$$
\vspace*{\fill}
\end{landscape}
\clearpage}
A \\
couple \\
more \\
lines \\
\section{Discussion}
\lipsum[2]
\begin{subequations}
\label{sf:2}
$$\label{sf:2a} y = {x\over 2}$$
$$\label{sf:2b} y = {2x \over 3}$$
\end{subequations}
\end{document}
Any ideas on how to return the correct equation numbering?
• The short answer is to use a savebox. – John Kormylo Oct 23 '15 at 18:32
• Why using afterpage? Simple mak a \clearpage before and after that extreme equation. – Johannes_B Oct 23 '15 at 18:38
• if in doubt don't use afterpage! (although in this case I can't really guess what afterpage is intended to do, it appears do be doing exactly what it is designed to do, move its content out of sequence to the later page). – David Carlisle Oct 23 '15 at 20:21
• If I use clearpage then the rest of the page is skipped, so I get a big blank space and then the equation. As the absolute position of the equation doesn't matter, I'd rather the text flowed around it. – JoeyCrossy Oct 26 '15 at 11:06
• Afterpage does move it out of sequence which is fine but it inserts it into lower subequations, which is not as the numbering is wrong. – JoeyCrossy Oct 26 '15 at 11:07
I couldn't find ociamthesis.cls so used article instead. Do not reuse \tempbox until the next page.
\documentclass[12pt]{article}
\usepackage{amsmath, pdflscape,afterpage,hyperref,lipsum}
\newsavebox{\tempbox}
\begin{document}
\lipsum[1-3]
The long equation is first referenced here. \par
\savebox{\tempbox}{\begin{minipage}{\textheight}
$$\label{sf:1} y = {a \over b} .$$%
\end{minipage}}
\vspace*{\fill}
\afterpage{
\clearpage
\begin{landscape}
\thispagestyle{empty}% just a suggestion
\vspace*{\fill}%
\noindent\usebox{\tempbox}\par
\vspace*{\fill}
\end{landscape}
\clearpage}
A \\
couple \\
more \\
lines \\
\section{Discussion}
\lipsum[2]
\begin{subequations}
\label{sf:2}
$$\label{sf:2a} y = {x\over 2}$$
$$\label{sf:2b} y = {2x \over 3}$$
\end{subequations}
\end{document}
• Thank you, this works! (The document class for the thesis is based off memoir, thought this seems like it will work for all classes.) – JoeyCrossy Oct 26 '15 at 11:18
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Article Contents
Article Contents
Time optimal control for a nonholonomic system with state constraint
• The aim of this paper is to tackle the time optimal controllability of an $(n+1)$-dimensional nonholonomic integrator. In the optimal control problem we consider, the state variables are subject to a bound constraint. We give a full description of the optimal control and optimal trajectories are explicitly obtained. The optimal trajectories we construct, lie in a 2-dimensional plane and they are composed of arcs of circle.
Mathematics Subject Classification: 49K15, 49K30, 49J15, 49J30, 37J60, 93C15.
Citation:
• [1] A. Agrachev, D. Barilari and U. Boscain, On the Hausdorff volume in sub-Riemannian geometry, Calc. Var. Partial Differential Equations, 43 (2012), 355-388.doi: 10.1007/s00526-011-0414-y. [2] A. A. Agrachev and Y. L. Sachkov, "Control Theory from the Geometric Viewpoint," Encyclopaedia of Mathematical Sciences, 87, Control Theory and Optimization, II, Springer-Verlag, Berlin, 2004. [3] L. Ambrosio, N. Fusco and D. Pallara, "Functions of Bounded Variation and Free Discontinuity Problems," Oxford Mathematical Monographs, The Clarendon Press, Oxford University Press, New York, 2000. [4] R. Beals, B. Gaveau and P. C. Greiner, Hamilton-Jacobi theory and the heat kernel on Heisenberg groups, J. Math. Pures Appl. (9), 79 (2000), 633-689.doi: 10.1016/S0021-7824(00)00169-0. [5] A. M. Bloch, Nonholonomic mechanics and control, With the collaboration of J. Baillieul, P. Crouch and J. Marsden, With scientific input from P. S. Krishnaprasad, R. M. Murray and D. Zenkov, Interdisciplinary Applied Mathematics, 24, Systems and Control, Springer-Verlag, New York, 2003.doi: 10.1007/b97376. [6] J. F. Bonnans and A. Hermant, Well-posedness of the shooting algorithm for state constrained optimal control problems with a single constraint and control, SIAM J. Control Optim., 46 (2007), 1398-1430.doi: 10.1137/06065756X. [7] R. W. Brockett, Control theory and singular Riemannian geometry, in "New Directions in Applied Mathematics" (Cleveland, Ohio, 1980), Springer, New York-Berlin, (1982), 11-27. [8] A. E. Bryson, Jr. and Y. C. Ho, Applied optimal control. Optimization, estimation, and control, Revised printing, Hemisphere Publishing Corp. Washington, D. C., distributed by Halsted Press [John Wiley & Sons], New York-London-Sydney, 1975. [9] L. Cesari, "Optimization-Theory and Applications. Problems with Ordinary Differential Equations," Applications of Mathematics (New York), 17, Springer-Verlag, New York, 1983. [10] F. H. Clarke, "Optimization and Nonsmooth Analysis," Second edition, Classics in Applied Mathematics, 5, Society for Industrial and Applied Mathematics (SIAM), Philadelphia, PA, 1990.doi: 10.1137/1.9781611971309. [11] J.-M. Coron, "Control and Nonlinearity," Mathematical Surveys and Monographs, 136, American Mathematical Society, Providence, RI, 2007. [12] L. C. Evans and R. F. Gariepy, "Measure Theory and Fine Properties of Functions," Studies in Advanced Mathematics, CRC Press, Boca Raton, FL, 1992. [13] R. F. Hartl, S. P. Sethi and R. G. Vickson, A survey of the maximum principles for optimal control problems with state constraints, SIAM Rev., 37 (1995), 181-218.doi: 10.1137/1037043. [14] R. A. Horn and C. R. Johnson, "Matrix Analysis," Cambridge University Press, Cambridge, 1985. [15] A. D. Ioffe and V. M. Tihomirov, "Theory of Extremal Problems," Studies in Mathematics and its Applications, 6, North-Holland Publishing Co., Amsterdam-New York, 1979. [16] J. Lohéac, J.-F. Scheid and M. Tucsnak, Controllability and time optimal control for low Reynolds numbers swimmers, Acta Applicandae Mathematicae, 123 (2013), 175-200.doi: 10.1007/s10440-012-9760-9. [17] C. Prieur and E. Trélat, Robust optimal stabilization of the Brockett integrator via a hybrid feedback, Math. Control Signals Systems, 17 (2005), 201-216.doi: 10.1007/s00498-005-0152-9. [18] A. Shapere and F. Wilczek, Efficiencies of self-propulsion at low Reynolds number, J. Fluid. Mech., 198 (1989), 587-599.doi: 10.1017/S0022112089000261.
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# Is there a case for ditching any of the paper tables in elementary statistics courses?
The textbook I'm using explains the it is "impractical" to have a normal distribution for all values of $\sigma$ and $\mu$, hence the standard normal distribution table.
To me, this simply doesn't ring true. We could have a phone app, to generate a distribution for $\sigma$ and $\mu$, then highlight the desired area.
http://homepage.stat.uiowa.edu/~mbognar/applets/normal.html
$P(x)=\frac{1}{\sigma \sqrt{2\pi}}e^{\frac{-(x-\mu)^2}{2\sigma^2}}$
But, is the standard normal distribution important beyond being a time-saving calculation tool? There are so many important concepts in statistics and so little time that it feels like a wasted opportunity to teach outdated calculation methods.
HOWEVER: Until there is a revision in the way that we teach elementary statistics, my students must learn these methods. The standard normal distribution is ubiquitous in math and science education. Students may need to learn about it to understand how other people may talk about statistics.
What should be the future of paper tables?
• The title asks whether we should ditch paper-based statistical tables, but the question asks why we need to convert to the standard normal distribution. These aren't quite the same thing. Can you make the connection clearer? – DavidButlerUofA Apr 22 '15 at 7:43
• In exam situations phone apps (or any device which can communicate electronically with other devbices) is usually not allowed ... Standardizing a variable is also a very basic operation which should be understood? – kjetil b halvorsen Apr 22 '15 at 8:26
• "The standard normal distribution is ubiquitous in math and science education." -- is it? I haven't seen it outside of a statistics course, honestly. – Chris Cunningham Apr 22 '15 at 14:47
• See also the related (but different) question matheducators.stackexchange.com/questions/5949/… – Chris Cunningham Apr 22 '15 at 14:58
• @Richard -- and not exactly "ubiquitous" is it? – DavidButlerUofA Apr 22 '15 at 22:41
This answer is not necessarily specific to statistical tables, but to table reading in general. I basically learned how to read and understand all types of tables including spreadsheets, train tables, and various mathematical tables by analyzing a physical table in my high school statistics class. The visual aspect of both the standard normal distribution, which most people will recognize without even knowing exactly what it is, and the layout of the table made it very easy for me to understand how the data was structured and organized. We had graphing calculators that could do it, but after some practice I actually found using the tables in the back of the textbook for quick check ups. I believe there is a lot of value in being able to read tables and the normal distribution is a great entry point into being able to really understand how to read them, and more importantly how to make them.
As far as pedagogical practice, I would suggest to let your students choose which to use on a day-to-day basis, but I would defiantly push them to at least be comfortable with both methods for the sake of testing etc. One thing that immediately comes to mind is to set up a weekly "competition" where students race using one of the two methods to solve a problem. Having them switch between the two each week could allow them to try to get Personal Bests and would be a great way to have them make a table to keep track of their own times :)
• Interesting perspective! – Chris Cunningham Apr 23 '15 at 16:42
As @kjetilbhalvorsen mentioned, tables are useful useful for old style pen and paper exams. They should be readily duplicated in a decent graphics calculator, but there are more important reasons that the days of the paper normal distribution table are dated.
First, the validity of using an exam to asses statistics has been largely jettisoned in some education systems, even where it is retained for other areas of maths.
Second, I find the conceit of using tables to get accurate values for a normal distribution, while the normal distribution itself is usually only a very rough approximation of the real life situation to be bizarre. IMHO a course specification asking that a rough approximation be applied to 3 sig.fig. is indicative of deep conceptual deficiencies in traditional statistics education.
The heuristic usefulness of normal distributions can be provided by a few critical values for hypothesis testing, without the use of tables.
As you suggested, there are much more important things to learn.
The standard normal distribution is very important concept that is completely separate from the standard normal table. The standard normal allows us to compare unlike variables. A typical example is comparing an athlete in one sport to another. You can understand and use the standard normal distribution without relying on the tables to do this. It is for this reason that I no longer paper tables and instead I have chosen have my students use the following normal distribution calculator:
http://davidmlane.com/hyperstat/z_table.html
I believe the table itself gets in the way of students seeing the big picture of what they are doing in using the normal distribution. The fact that the table only gives P(z<=Z) means extra computation steps that are basically irrelevant to understanding how the normal distribution works. It is another typical statistics example where computation obfuscates what is actually going on.
To address concerns about students using apps on quizzes, I have designed my quizzes to focus on interpretation rather than computation. I will only ask students to compute values for labs and projects. This makes it so that apps are not necessary on quizzes and so I can evaluate my students ability to understand the meaning of important ideas. I have found that when computation is necessary, I can ask students to apply the empirical rules to demonstrate understanding.
A final note: This choice also depends on what your students' next courses will be. I teach an introductory high school course. I expect that my students will take an introductory college course. If that course does not use a table, great! If it does, they will have adequate conceptual preparation that will prepare them to learn it during that class.
• But we could use any normal distribution as the standard. There is nothing special about having sigma=1 and mu=0-- that said I do think a problems that as students to compare more than one distribution or find regions of equivalent area for different scales are very important. – futurebird Apr 23 '15 at 19:24
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Title: Superpositivity of L-functions and "completion of square" Speaker: Prof. Wei Zhang (MIT) Time: 2018-1-12, 10:30-11:30 Place: Lecture;Hall;of;Siyuan;Building Abstract: We explain how Riemann hypothesis and its generalization imply the positivity of the special values of all derivatives of normalized L-functions. This rises a question: can one interpret these positive values as squares? We present some examples of such interpretations, in the joint work with Xinyi Yuan and Shouwu Zhang over number fields on Gross-Zagier formula, and with Zhiwei Yun over function fields on Higher Gross-Zagier formula respectively. Attachment: intro higher GZ.pdf
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# Solution - In an Equilateral Triangle Abc, D is a Point on Side Bc Such that Bd = 1/3bc . Prove that 9 Ad^2 = 7 Ab^2 - Pythagoras Theorem
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#### Question
In an equilateral triangle ABC, D is a point on side BC such that BD = 1/3BC . Prove that 9 AD2 = 7 AB2
#### Solution
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Solution for question: In an Equilateral Triangle Abc, D is a Point on Side Bc Such that Bd = 1/3bc . Prove that 9 Ad^2 = 7 Ab^2 concept: Pythagoras Theorem. For the course CBSE
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# Thread: Error building application - ClassRequire
1. ## Error building application - ClassRequire
Hi,
I'm having a problem with sencha cmd app watch; Below the error:
[ERR] com.sencha.exceptions.ExBuild: Failed to find any files for path\to\view\Form.js::ClassRequire::Ext.ux.form.MultiSelect
The strange thing is that the "MultiSelect.js" file is present in the the ext/packages/ux/classic/src/form folder; I put a new entry in bootstrap.json => paths this way:
"Ext.ux.form.MultiSelect": "ext/packages/ux/classic/src/form/MultiSelect.js",
This actually fixed the problem, at least this fixes the problems in browser, after the app is deployed..... but, the server won't start because of the error above.
Anyone of you ever faced things like this?
Any help appreciated,
Thanks
2. Hi--,
You likely just need to add the ux to your requires (app.json).
If you modify/add the following to your app.json does it produce a better result?
PHP Code:
"requires": [ "font-awesome", "ux"],
Best!
Bryan
3. Thanks!this worked like a charm
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J E L L Y E N T
The DHS websites platform is for the time being unavailable. Our programs
must be abet up nearly straight away. Please near abet and take a look at again rapidly.
Reference ID:
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With the exception of helium, the noble gases all have s and p electron coverings and are unable to easily create chemical compounds. These elements include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). The noble gases: group 8. Have 8 valence electron at their valence shell except for helium which has 2 valence electron. Why are the elements of Group 8 called the noble or inert gas elements? credit by exam that is accepted by over 1,500 colleges and universities. The noble gases already have a full set of valence electrons; this means they don't need to bond or attach to other elements to achieve stability. They are in group 8 (18 if you include transition metals), the right-most column of the table. What are Noble Gases or Inert Gases? Like neon and argon, krypton can be found in neon signs. Well, the fifth noble gas, xenon, doesn't disappoint either. the density decreases ? These elements are gases at ordinary room temperature and pressure. | {{course.flashcardSetCount}} All of the elements in Group Zero are noble gases. The noble gases are a group of elements wearing crowns, sitting on thrones and feasting on the finest foods. They are monatomic, which means they exist as individual atoms. Characteristics. It is very soluble in water, but is fairly unreactive in other compounds. Group 18 of the modern periodic table consists of noble gases. Noble gas definition is - any of a group of rare gases that include helium, neon, argon, krypton, xenon, and usually radon and that exhibit great stability and extremely low reaction rates —called also inert gas. Because of this, they considered non-reactive. The noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). Choose from 388 different sets of term:noble gases = a group 8 element flashcards on Quizlet. Noble gas electronic structure. For example, those with nobility have a life that's quite different from your average, everyday person. Their uses depend on their inertness, low density and non-flammability. They are commonly called Group 18, the inert gases, the rare gases, the helium family, or the neon family. Services. The outer shell of valence electrons is considered to be “full” in noble gases, giving them little tendency to participate in chemical reactions. Okay, maybe this colorless, tasteless and odorless gas isn't hanging out with famous people and staying up late, but it is invading homes. Test yourself on this group of gases with these practice questions about their reactivity and applications. Xenon. As a member, you'll also get unlimited access to over 83,000 The list includes helium, neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). But, did you know that even though helium isn't found in high concentrations on Earth, it's the second most abundant element in the universe! Let's start our noble gas tour with helium. The noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). Learn faster with spaced repetition. Covers electronic configuration of noble gases and the reactivity of noble gases. Why can the noble gases be called group 8? Learn term:group 8 = noble gases with free interactive flashcards. They are unreactive because their atoms have stable arrangements of electrons. Densities of the noble gases. How Do I Use Study.com's Assign Lesson Feature? Sinks. the reactivity decreases; Which statement is TRUE about the Group of Noble Gases? Their uses depend on their inertness, low density and non-flammability. It was discovered in 1899, and is one of the last elements in Group 8. Group 0/8 / Noble Gases. Plus, get practice tests, quizzes, and personalized coaching to help you Radioactive radon was added to the list by German ch… Where are the noble gases on the periodic table? Radon is radioactive and can be found in the ground where it can escape into your house. Hydrogen, as it turns out, was a bit unsafe for blimp passengers. Group 8 The noble gases (Helium (Symbol: He, Appearance: Colourless gas,…: Group 8 The noble gases Neon is used in advertising signs. • Each noble gas emits a characteristic color in a gas discharge tube. They are colorless, odorless and tasteless. Welcome to the noble gases. They are also called the inert gases. Wow, so many names for the same thing! The group 0 elements are placed in the rightmost column of the periodic table. 18 chapters | It's also been used as a test element for the development of special spacecraft engines! the boiling points decrease ? The noble gases were all isolated for the first time within a period of only five years at the end of the 19th century. In the case of Neon (Ne), for example, both the n = 1 and n = 2 shells are complete and therefore it is a stable monatomic gas under ambient conditions. These elements are also known as the inert gases, which is a very appropriate name for them since this group of elements exhibits extremely inert chemical behaviour. Elements are grouped according to chemical properties. and career path that can help you find the school that's right for you. Group 8 (current IUPAC) should not be confused with "group VIIIA" in the CAS system, which is group 18 (current IUPAC), the noble gases. Most other gases are diatomic. Elements in the noble gas family have atoms with a full outer shell of electrons. Collectively these gases are known as the noble gases. They are unreactive because their atoms have stable arrangements of electrons. Enrolling in a course lets you earn progress by passing quizzes and exams. • Noble gases are colorless, odorless, and tasteless. Unreactive. | 1 Inclusion trapped fluids: tracing ancient fluids using noble gases.-.11. Why can the noble gases be called group 0. Such as Light Bulbs, Camera Flashes. Element 5- Xenon Trends and Patterns Radon is a radioactive gas that is the leading cause of lung cancer. These gases are monoatomic and chemically inert under normal conditions and hence are also named as inert gases. flashcard set{{course.flashcardSetCoun > 1 ? Contributors; The properties of the noble gases are summarized in the table below. When you mention krypton, many people think of Superman's home planet and not the noble gas. They are called the noble gases because they are all chemically unreactive (the term noble in chemistry signifies a lack of chemical reactivity). The elements considered noble gasses are: Helium (He) Neon (Ne) Argon (Ar) Krypton (Kr) Xenon (Xe) Radon (Rn) Oganesson (Og) The nobel gases have high ionization energy and very low electron affinity. Biology Lesson Plans: Physiology, Mitosis, Metric System Video Lessons, Lesson Plan Design Courses and Classes Overview, Online Typing Class, Lesson and Course Overviews, Personality Disorder Crime Force: Study.com Academy Sneak Peek. More specifically, they are odorless, colorless and tasteless gases. A balloon filled with helium rises quickly in air. The noble gases are one of the better known groups of elements in the Periodic Table, and whilst some of their applications are obvious, such as the use of helium in balloons, others, such as the use of xenon in medical imaging and as a neuroprotector, or the use of helium as a carrier gas in gas chromatography, are a little more obscure. Not sure what college you want to attend yet? The group 0 elements, the noble gases, are all unreactive non-metal gases. Group 0 – Noble Gases. The noble gases are a set of chemical elements that behave similarly. This lesson will explore the properties that the noble gases share and will look at some of their uses. A radioactive version of krypton is used in nuclear reactors. The elements in Group 18 of the periodic table are known as the noble gases. These gases all have similar properties under standard conditions: they are all odorless, colorless, monatomic gases with very low chemical reactivity. NEW! Helium. Rises. They have low melting and low boiling points. Did you know… We have over 220 college Choose from 391 different sets of term:group 8 = noble gases flashcards on Quizlet. The analysis and interpretation of noble gases in modern hydrothermal systems.- 10. Jump to Question. They can be found in small amounts in the Earth's crust and the Earth's atmosphere. An error occurred trying to load this video. All of the noble gases are similarly unreactive. Although the noble gases can be found on Earth, together they only make up about 1% of the Earth's atmosphere. At the bottom of the group, a balloon filled with xenon falls quickly. neon ? During Mendeleev's time, noble gases were not discovered. Breathing too much can cause lung damage and even lung cancer. Are the noble gases metals or non-metals? This is because helium can be found in stars. Nitrogen (N 2) might be considered an inert gas, but it is not a noble gas. With the exception of radon, I'd say the noble gases have all the fun. It is also used in deep sea diving to prevent decompression sickness, which can cause serious problems for divers, including death. Working Scholars® Bringing Tuition-Free College to the Community. 0 0. The Noble gases are in Group 8 (or Group 0) and have very low melting and boiling points. Log in or sign up to add this lesson to a Custom Course. They are the most stable due to having the maximum number of valence electrons their outer shell can hold. Practice. Log in here for access. The Noble gases are in Group 8 (or Group 0) and have very low melting and boiling points. All noble gases have full outer electron shells and do not need to gain, lose or share electrons. They show trends in their physical properties. Some luxury car owners put argon in their tires to protect the rubber and reduce noise. The six noble gases that occur naturally are helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn). The group 0 elements, the noble gases, are all unreactive non-metal gases. The other representative elements don't have a full set of valence electrons, so they bond with other elements in order to achieve stability. ... Give three examples of elements that are liquids and three examples of elements that are gases at $30^{\circ} \mathrm{C}$ . The noble gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn). The same probably applies to Ar. The noble gases are in Group 18 (8A).They are helium, neon, argon, krypton, xenon, and radon.They were once called inert gases because they were thought to be completely inert—unable to form compounds.This is a reasonable belief because the noble gases have a complete octet, making them very stable and unlikely to gain or lose any electrons. All of the noble gases are present in Earth’s atmosphere and are colorless, odorless, tasteless, and nonflammable. All of the noble gases are present in Earth’s atmosphere and are colorless, odorless, tasteless, and nonflammable. lessons in math, English, science, history, and more. They are located to the far right of the periodic table and make up the eighteenth column. Group 0 – Noble Gases. Once you are finished, you should be able to: To unlock this lesson you must be a Study.com Member. The noble gases are the chemical elements in group 18 of the periodic table. This means that: The noble gases are very stable and the most unreactive (or inert) of all the elements. 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These elements are gases at ordinary room temperature and pressure. Learn more about noble gases with this article. It was discovered in 1899, and is one of the last elements in Group 8. When they do, the most common oxidation number is 2. All rights reserved. Noble Gases []. The noble gases are a group of chemical elements that make up Group 18 on the periodic table. At the bottom of the group, a balloon filled with xenon falls quickly. The noble gases are also referred to as Group 8A, Group 18, Group VIIIA and even Group 0. The group consists of 7 elements: helium, neon, argon, krypton, xenon, and radon. It is There are six gaseous elements located in group 8A (or group 18) of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). To learn more, visit our Earning Credit Page. • All Group 8A elements are monatomic gases at STP. Neon. Most of them can also be found in the Earth's crust, but only in small amounts. Sinks. The elements in Group 18 of the periodic table are known as the noble gases. [gp0-21] ? The noble gases in group 8 of the periodic table are used to demonstrate the impact of density on balloons filled with different gases. 7. The melting and boiling points (physic… Test yourself on this group of gases with these practice questions about their reactivity and applications. Noble Gases - The Gases In Group 18 | Properties of Matter | Chemistry | FuseSchoolHave you ever heard the term "Noble Gases" before? This indicates how strong in your memory this concept is. Noble gases are the elements of group 18 of the periodic table of elements. Learn term:noble gases = a group 8 element with free interactive flashcards. Noble gases in oil and gas accumulations 9. Get the unbiased info you need to find the right school. Helium has several commercial uses (other than balloons!). The noble gases are another group of well-studied elements in the periodic table with a specific set of properties that make them unique. Rises. You should test your home for Eventually, in 1898, he teamed up with the English chemist, Morris Travers and discovered krypton, neon, and xenon. Sure enough,the ionization energies of He and Ne are greater than 2000 kJ mol –1, and it is unlikely that these noble gases will ever be induced to form chemical bonds. You should test your home for The noble gases have also been referred to as inert gases, but this label is deprecated as many noble gas compounds are now known. The Noble gases are found in group 8(or 0) of the periodic table, on the far right hand side.Their names are helium, neon, argon, krypton, xenon and radon. She has a Bachelor of Science in Biology and a Master of Education. Traits down a group. Preview; Assign Practice; Preview. They are the most stable due to having the maximum number of valence electrons their outer shell can hold. They also have low melting and boiling points. [gp0-11] ? Also helium is used in divers oxygen takes to prevent to formation of gas bubbles. Despite their name, the noble gases aren't actually nobility, but they are a group of gases located on the far right of the periodic table. The Study-to-Win Winning Ticket number has been announced! MEMORY METER. Next is krypton, which has spent some time in the spotlight. They show trends in their physical properties. [gp0-22] The individual elements making up the noble gases are quite fascinating, so let's take a moment to look at each one. Spanish Grammar: Describing People and Things Using the Imperfect and Preterite, Talking About Days and Dates in Spanish Grammar, Describing People in Spanish: Practice Comprehension Activity, Quiz & Worksheet - Employee Rights to Privacy & Safety, Flashcards - Real Estate Marketing Basics, Flashcards - Promotional Marketing in Real Estate. courses that prepare you to earn It's used in light bulbs to prevent them from burning out so fast, as well as in some neon signs where it emits a blue glow. What elements are noble gases? {{courseNav.course.mDynamicIntFields.lessonCount}} lessons Choose from 391 different sets of term:group 8 = noble gases flashcards on Quizlet. Members of the Inert Gas Family. Try refreshing the page, or contact customer support. Group 8 Elements. Already registered? They are located to the far right of the periodic table and make up the eighteenth column. Their uses depend on their inertness, low density and non-flammability. What chemical property determines the placement of the noble gases on the periodic table? These elements are also known as the inert gases, which is a very appropriate name for them since this group of elements exhibits extremely inert chemical behaviour. The noble gases make up the last column of elements in the periodic table. We've got neon signs, blimps, balloons, fancy cars and even Superman! Noble gases are also known as inert and rare gases. The noble gases are an inert group of elements with some fun and fascinating uses. … Decisions Revisited: Why Did You Choose a Public or Private College? They are called the noble gases because they are all chemically unreactive (the term noble in chemistry signifies a lack of chemical reactivity). Like their name implies, noble gases are gases at room temperature. Noble gases are the elements of group 18 of the periodic table of elements. Most other gases are diatomic. This means that: The noble gases are very stable and the most unreactive (or inert) of all the elements. This group consists of a chemical series of gases including Argon, helium, neon, krypton, xenon, and radon. The noble gases … A balloon filled with helium rises quickly in air. Elements are stable when they have a full set of valence electrons, or the outermost electrons that are farthest away from the nucleus. Which statement is TRUE about the trend, with increasing atomic number, down the Group of Noble Gases? Wow, argon really is keeping with its nobility persona, driving around with the rich and famous in luxury cars! Sure enough,the ionization energies of He and Ne are greater than 2000 kJ mol –1, and it is unlikely that these noble gases will ever be induced to form chemical bonds. They are commonly called Group 18, the inert gases, the rare gases, the helium family, or the neon family. Cole H. Baylor University. 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Chapter 9.2, Problem 7SWU
### Calculus: An Applied Approach (Min...
10th Edition
Ron Larson
ISBN: 9781305860919
Chapter
Section
### Calculus: An Applied Approach (Min...
10th Edition
Ron Larson
ISBN: 9781305860919
Textbook Problem
1 views
# In Exercises 5-7, evaluate the definite or improper integral. ∫ 0 ∞ 3 e − 3 t d t
To determine
To calculate: The solution of the improper integral 03e3tdt
Explanation
Given Information:
The provided improper integral is 03e3tdt.
Formula used:
If the limit defining the improper integral is a unique finite number, then integral converges else it diverges,
af(x)dx=limbabf(x)dx
According to the exponential rule of integrals,
exdx=ex+C
Calculation:
Consider the given equation,
I=03e3t
Now, use the formula, af(x)dx=limbabf(x)dx to rewrite the integral as,
I=03e3t=limb0b3e3tdx
Now, integrate,
I=limb0b3eȡ
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# Would our orbit really remain the same if the sun were a black hole of equal mass?
There seems to be an idea floating around that the sun could be replaced by anything of equal mass with no consequence to our orbit.
It seems to me that if the mass of the sun were confined to a single point that the local geometry of space would be different, therefore our orbit and those of the other planets would also be different.
1. Am I mistaken to think of this as analogous to distribution of weight on an elastic surface? - (A more confined distribution of mass would create a deeper gravity well, so to speak).
2. I'm thinking that angular momentum would need to be conserved and that might result in frame dragging which may need to be accounted for, but I'm not sure and I don't know how to calculate it (yet).
3. Anything I'm overlooking?
P.S. I know black holes don't come in our size.
Thanks!
## 3 Answers
It depends what you mean by 'Would remain the same'. If you are asking about the exact precise orbit, the answer is yes, it would change, since the Schwarzschild (and also Kerr solution of a rotating black hole) solution is a vacuum solution of the Einstein equations, so it describes strictly speaking only Vacuum, with a curvature singularity in the centre. Since the Sun is made out of matter, has a finite size and you need many, many variables to fully describe it (for example it is non-spherical) the metric around it is not Schwarzschild (remember that a Schwarzschild black hole is only described by one parameter).
However, the Schwarzschild metric is a good approximation around the Sun, and for current observational purposes it describes nature well. What one should do, is to calculate the perturbations around the Schwarzschild metric in some form of power series in the characteristic length scale of the Sun over the Schwarzschild radius of the Sun. You will then find that these corrections are negligible at our current measurement capabilities. This last statement is with the exception of the advancement of the perihelion of Mercury, where we can now measure the quadrupole moment $$J_2$$ of the sun to be non-zero. This means that one should replace the Sun not with a Schwarzschild black hole, but with a Kerr black hole (to achieve a non-vanishing quadrupole moment).
As an aside, it is also important to note that the parameter that describes a Schwarzschild black hole $$M$$ is precisely constructed such that the physics around that central object reduces to the orbits of a body with mass $$M$$ in Newtonian gravity. It is therefore not surprising that the orbits do not change that much far from the event horizon.
• Thanks konstle. That's very insightful. Apr 10, 2022 at 0:45
• “ You will then find that these corrections are negligible at our current measurement capabilities.” Citation needed. These corrections are certainly significant for Mercury’s orbit. Apr 10, 2022 at 6:52
• @mmeent are you sure about that? Note that we're not talking about corrections due to general relativity versus Newtonian gravity, but rather (if I understand correctly) corrections due to the sun's mass distribution not being perfectly spherical. Apr 10, 2022 at 7:08
• I misremembered the effect of the quadrupole moment by about an order of magnitude. It is currently on the cusp of being significant for Mercury, which makes it certainly insignificant for the Earth’s orbit. Nonetheless the assertion that it is insignificant in this answer needs to be backed up with something more factual. Apr 10, 2022 at 7:29
• @mmeent I added a comment and a reference to the answer. For example from measurements with MESSENGER spacecraft one finds a a non-vanishing quadrupole moment of the Sun. This means that a Schwarzschild black hole is insufficient to explain the metric surrounding it. Apr 10, 2022 at 15:25
There seems to be an idea floating around that the sun could be replaced by anything of equal mass with no consequence to our orbit.
I have to correct my former answer. That idea is correct!
Let's assume the earth is orbiting in the static spherically symmetric spacetime shaped by the sun (we neglect the earth contribution to spacetime curvature). The corresponding metric is the famous Schwarzschild solution of Einstein field equations (https://arxiv.org/abs/physics/9905030) : $$$$ds^2=\Big(1-\frac{2GM}{c^2 r}\Big)~c^2 dt^2-\Big(1-\frac{2GM}{c^2 r}\Big)^{-1} dr^2-r^2 d\Omega^2.$$$$ That metric depends only on the parameter $$M$$, thus, any other spherical gravitational object with the same mass, including a black hole, will have the same exterior spacetime geometry. Orbits, as geodesics of that spacetime, will be identical, too.
• Thanks Jan, this is a great answer, specifically in that address is point #1 of my question quite succinctly. This may be a lot to ask, but if you happen to have a link to the compactness parameter so that I might read more about it, that would be fantastic. In any case, thanks for the insight. Apr 10, 2022 at 20:48
• @StuartB, if you like take a look into physics.stackexchange.com/a/679431/281096. However, today I have become doubts whether my answer is correct. I am checking it now using mathematics from arxiv.org/abs/0812.1806v3. Apr 11, 2022 at 11:20
• @StuartB, I have had to correct me, see the answer again! Apr 11, 2022 at 14:48
• Thanks for setting this straight Jan! Apr 12, 2022 at 1:51
Yes, the number of gravitational degrees of freedom remains the same if the Sun were magically turned into a black hole. Now apply that to disk-like interaction, and you have focused, super strong gravitation. Count.
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## Linear Algebra and Its Applications, Review Exercise 2.4
Review exercise 2.4. Given the matrix
$A = \begin{bmatrix} 1&2&0&2&1 \\ -1&-2&1&1&0 \\ 1&2&-3&-7&-2\end{bmatrix}$
find its echelon form $U$ and the dimensions of the column space, nullspace, row space, and left nullspace of $A$.
Answer: We perform elimination on $A$ to reduce it to echelon form. In the first step we multiply the first row of $A$ by -1 and subtract it from the second row:
$\begin{bmatrix} 1&2&0&2&1 \\ -1&-2&1&1&0 \\ 1&2&-3&-7&-2\end{bmatrix}$
$\Rightarrow \begin{bmatrix} 1&2&0&2&1 \\ 0&0&1&3&1 \\ 1&2&-3&-7&-2\end{bmatrix}$
and then multiply the first row of $A$ by 1 and subtract it from the third row:
$\begin{bmatrix} 1&2&0&2&1 \\ 0&0&1&3&1 \\ 1&2&-3&-7&-2\end{bmatrix}$
$\Rightarrow \begin{bmatrix} 1&2&0&2&1 \\ 0&0&1&3&1 \\ 0&0&-3&-9&-3\end{bmatrix}$
Finally we multiply the second row of $A$ by 1 and subtract it from the third row:
$\begin{bmatrix} 1&2&0&2&1 \\ 0&0&1&3&1 \\ 0&0&-3&-9&-3\end{bmatrix}$
$\Rightarrow \begin{bmatrix} 1&2&0&2&1 \\ 0&0&1&3&1 \\ 0&0&0&0&0\end{bmatrix}$
The resulting matrix
$U = \begin{bmatrix} 1&2&0&2&1 \\ 0&0&1&3&1 \\ 0&0&0&0&0\end{bmatrix}$
is in echelon form with pivots in columns 1 and 3.
Since $U$ has two pivots its rank $r = 2$. The rank of $A$ is the same as the rank of $U$ so the rank of $A$ is also $r = 2$. This is the dimension of the column space of $A$.
The number of columns of $A$ is $n = 5$ so the dimension of the nullspace of $A$ is $n - r = 5 - 2 = 3$.
The dimension of the row space of $A$ is the same as that of the column space of $A$, so the dimension of the row space of $A$ is also $r = 2$.
Finally, the number of rows of $A$ is $m = 3$ so the dimension of the left nullspace of $A$ is $m - r = 3 - 2 = 1$.
NOTE: This continues a series of posts containing worked out exercises from the (out of print) book Linear Algebra and Its Applications, Third Edition by Gilbert Strang.
If you find these posts useful I encourage you to also check out the more current Linear Algebra and Its Applications, Fourth Edition, Dr Strang’s introductory textbook Introduction to Linear Algebra, Fourth Edition and the accompanying free online course, and Dr Strang’s other books.
This entry was posted in linear algebra. Bookmark the permalink.
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# The line current in a three-phase system are Ia = 4∠60°, Ib = 0, Ic = 4∠-120°, find the negative sequence current:
1. 12.909 ∠-30°
2. 2.309 ∠30°
3. 3.303 ∠60°
4. 6.913 ∠70°
Option 2 : 2.309 ∠30°
## PU System and Symmetrical Components MCQ Question 1 Detailed Solution
Concept:
The relation between the line currents in terms of the symmetrical components of currents is given below.
$$\left[ {\begin{array}{*{20}{c}} {{I_a}}\\ {{I_b}}\\ {{I_c}} \end{array}} \right] = \left[ {\begin{array}{*{20}{c}} 1&1&1\\ 1&{{a^2}}&a\\ 1&a&{{a^2}} \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {{I_{a0}}}\\ {{I_{a1}}}\\ {{I_{a2}}} \end{array}} \right]$$
$$\left[ {\begin{array}{*{20}{c}} {{I_{a0}}}\\ {{I_{a1}}}\\ {{I_{a2}}} \end{array}} \right] = \frac{1}{3}\left[ {\begin{array}{*{20}{c}} 1&1&1\\ 1&a&{{a^2}}\\ 1&{{a^2}}&a \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {{I_a}}\\ {{I_b}}\\ {{I_c}} \end{array}} \right]$$
Ia0 = Zero Sequence Component of Current
Ia1 = Positive Sequence Component of Current
Ia2 = Negative Sequence Component of Current
a = 1∠120°, which represents the rotation of 120° in clockwise direction.
a2 = 1∠-120° or 1∠240° in anticlockwise direction or in clockwise direction, respectively.
Calculation:
Ia = 4∠60°, I= 0, Ic = 4∠-120°
Negative sequence component of current,
$${I_{a2}} = \frac{1}{3}\left( {{I_a} + {a^2}{I_b} + a{I_c}} \right) = \frac{1}{3}\left( {4\angle 60^\circ + \left( {1\angle - 120^\circ } \right)\left( 0 \right) + 1\angle 120^\circ \left( {4\angle - 120^\circ } \right)} \right)$$
$${I_{a2}} = \frac{1}{3}\left( {4\angle 60^\circ + 1\angle 120^\circ \left( {4\angle - 120^\circ } \right)} \right)$$
⇒ Ia2 = 2.309∠30°
# Which of the following is not a valid method of neutral grounding?
1. Solid grounding
2. Reactance grounding
3. Voltage transformer ground
4. Pulse transformer grounding
Option 4 : Pulse transformer grounding
## PU System and Symmetrical Components MCQ Question 2 Detailed Solution
Solid grounding:
In this type of neutral grounding, the neutral of the system is directly connected to the ground through a conductor of negligible resistance and reactance.
Reactance grounding:
In this method, a reactance is inserted between the neutral and ground to limit the fault current. This method has high transient voltages that appear under fault conditions.
Voltage Transformer Earthing:
In this method of neutral earthing, the primary of a single-phase Voltage Transformer Earthing is connected between the neutral and the earth.
Pulse transformer:
• A pulse transformer is not used for neutral grounding.
• A transformer that is enhanced to produce electrical pulses with high velocity, as well as stable amplitude, is known as a pulse transformer.
• A pulse transformer is basically a 1:1 transformer, which is primarily used in gate terminal firing circuits in power electronic devices such as SCR.
• It is used to isolate the low power gate firing circuit, from the high power circuit for which SCR is being used.
# The relation between the old and new per unit impedance values is given by:
1. $$Z_{pu}^{new} = Z_{pu}^{old}\frac{{S_B^{old}}}{{S_B^{new}}}{\left( {\frac{{V_B^{old}}}{{V_B^{new}}}} \right)^2}$$
2. $$Z_{pu}^{new} = Z_{pu}^{old}\frac{{S_B^{new}}}{{S_B^{old}}}{\left( {\frac{{V_B^{old}}}{{V_B^{new}}}} \right)^2}$$
3. $$Z_{pu}^{new} = Z_{pu}^{old}\frac{{S_B^{new}}}{{S_B^{old}}}{\left( {\frac{{V_B^{new}}}{{V_B^{old}}}} \right)^2}$$
4. $$z_{pu}^{old} = Z_{pu}^{new}\frac{{S_B^{new}}}{{S_B^{old}}}{\left( {\frac{{V_B^{old}}}{{V_B^{new}}}} \right)^2}$$
Option 2 : $$Z_{pu}^{new} = Z_{pu}^{old}\frac{{S_B^{new}}}{{S_B^{old}}}{\left( {\frac{{V_B^{old}}}{{V_B^{new}}}} \right)^2}$$
## PU System and Symmetrical Components MCQ Question 3 Detailed Solution
The relation between new per-unit value & old per unit value impedance
$${({Z_{pu}})_{new}}\; = {({Z_{pu}})_{old}} \times {\left( {\frac{{k{V_{base}}}}{{k{V_{new}}}}} \right)^2} \times \;\left( {\frac{{MV{A_{new}}}}{{MV{A_{old}}}}} \right)$$
Also $${Z_{pu}} = \frac{{{Z_{Actual}}}}{{{Z_{base}}}}$$
$${Z_{base}} = \frac{{kV_{base}^2}}{{MV{A_{base}}}}$$
Where,
(Zpu)new = New per unit value of impedance
(Zpu)old = Old per unit value of impedance
kVbase = Old base value of voltage
kVnew = New base value of voltage
MVAnew = New base value of power
MVAold = Old base value of power
# A 22 kV, 400 MVA generator has the reactance of 0.3 pu. The value of reactance on the new base of 25 kV and 200 MVA will be:
1. 0.116 pu
2. 032 pu
3. 0.58 pu
4. 0.232 pu
Option 1 : 0.116 pu
## PU System and Symmetrical Components MCQ Question 4 Detailed Solution
Concept:
$$p{u_{new}} = p{u_{old}}{\left( {\frac{{k{V_{old}}}}{{k{V_{new}}}}} \right)^2}\left( {\frac{{MV{A_{new}}}}{{MV{A_{old}}}}} \right)$$
Where kVold = old base value of voltage,
kVnew = New base value of voltage,
MVAold = Old base value of machine rating,
MVAnew = New base value of machine rating,
Calculation:
$$p{u_{new}} = 0.3 \times {\left( {\frac{{22}}{{25}}} \right)^2} \times \left( {\frac{{200}}{{400}}} \right)$$
punew = 0.116
# In an unbalanced three phase system, phase current Ia = 1∠(-90°) pu, negative sequence current Ib2 = 4 ∠(-150°) pu, zero sequence current IC0 = 3∠ 90° pu. The magnitude of phase current Ib in pu is
1. 1.00
2. 7.81
3. 11.53
4. 13.00
Option 3 : 11.53
## PU System and Symmetrical Components MCQ Question 5 Detailed Solution
Concept:
Fortescue’s Theorem:
A unbalance set of ‘n’ phasors may be resolved into (n - 1) balance n-phase system of different phase sequence and one zero phase sequence system.
A zero-phase sequence system is one in which all phasors are of equal magnitude and angle.
Considered three phasors are represented by a, b, c in such a way that their phase sequence is (a b c).
The positive phase sequence will be (a b c) and the negative phase sequence will be (a c b).
Assumed that subscript 0, 1, 2 refer to zero sequences, positive sequence, negative sequence respectively.
Current Ia, Ib, Ic represented an unbalance set of current phasor as shown,
Each of the original unbalance phasor is the sum of its component and it can be written as,
Ia = Ia0 + Ia1 + Ia2
Ib = Ib0 + Ib1 + Ib2
Ic = Ic0 + Ic1 + Ic2
For a balance position phase sequence (a b c) we can write the following relation,
Ia0 = Ib0 = Ic0
Ib1 = α2 Ia1
Ic1 = α Ia1
Ib2 = α Ia2
Ic2 =α2 Ia2
From the above equation Ia, Ib, Ic can be written in terms of phase sequence component,
Ia = Ia0 + Ia1 + Ia2
Ib = Ib0 + α2 Ia1 + α Ia2
Ic = Ia0 + α Ia1 + α2 Ia2
The above equation can be written in form of Matrix as shown,
$$\left[ {\begin{array}{*{20}{c}} {{I_a}}\\ {{I_b}}\\ {{I_c}} \end{array}} \right] = \left[ {\begin{array}{*{20}{c}} 1&1&1\\ 1&{{α ^2}}&α \\ 1&α &{{α ^2}} \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {{I_{a0}}}\\ {{I_{a1}}}\\ {{I_{a2}}} \end{array}} \right]$$
Calculation:
Ia = 1∠-90° P.u
Ib2 = 4∠-150° P.u
Ic0 = 3∠90° P.u
Ia = Ia1 + Ia2 + Ia0
Ib2 = α Ia2
⇒ 4∠-150° = (1∠120°) Ia2
⇒ Ia2 = 4∠-270°
Ia0 = Ib0 = Ic0 = 3∠90°
Ia1 = 8∠90°
Ib1 = α2 Ia1 = 8∠150°
Ib = Ib0 + Ib1 + Ib2
= 8∠150° + 4∠-150° + 3∠90°
= 11.53∠154.4°
Therefore the magnitude of phase current Iin pu is 11.53∠154.4°
# Which of the following depicts Per-unit value of a quantity?
1. Ratio of Actual quantity in any unit to Base or reference value of quantity in the same unit
2. Ratio of Base of reference value of quantity in the same unit to Actual quantity in any unit
3. Half of the Actual quantity in any unit
4. Twice of the Actual quantity in any unit
Option 1 : Ratio of Actual quantity in any unit to Base or reference value of quantity in the same unit
## PU System and Symmetrical Components MCQ Question 6 Detailed Solution
Per unit (p.u.) quantity:
The per-unit value of any quantity is defined as the ratio of actual value in any unit to the base or reference value in the same unit.
The per-unit value is dimensionless.
Per unit impedance (Zpu):
Zpu is defined as the ratio of actual value to base impedance.
It is also defined as The ratio of full-load volt-amperes to short-circuit volt-amperes.
$${Z_{pu}} = \frac{{Z{_a}}}{{Z_B}}$$
$${Z_{pu}} = \frac{{{Z_{a}} \times {{\left( {kVA} \right)}_B}}}{{\left( {kV} \right)_B^2 \times 1000}}$$
Za = Actual impedance
ZB = Base impedance
(kVA)B = Base kVA
(kV)B = Base voltage in kV
Important points:
• Per unit voltage (Vpu) = (kV)actual / (kV)B
• Short circuit current in pu = Actual current / Base current
# Symmetrical components are used in power system for the analysis of
1. Balanced 3-phase fault
2. Unbalanced 3-phase fault
3. Normal power system under steady conditions
4. Stability of system under disturbance
Option 2 : Unbalanced 3-phase fault
## PU System and Symmetrical Components MCQ Question 7 Detailed Solution
Symmetrical components:
Any unbalanced system of n phasors can be resolved into the n-system of balanced phasors. These subsystems of balanced phasors are called symmetrical components. These are used in the analysis of unbalanced three-phase faults.
Positive sequence components:
Set of three phasors equal in magnitude, displaced from each other by 120° in phase, and having the same phase sequence as the original phasors constitute positive sequence components. They are denoted by suffix 1.
Negative sequence components:
Set of three phasors equal in magnitude, displaced from each other by 120° in phase, and having phase sequence opposite to that original phasors constitute the negative sequence component. They are denoted by suffix 2.
Zero sequence components:
The set of three phasors equal in magnitude and all phases (with no mutual phase displacement) constitute zero sequence components. They are denoted by suffix 0.
# For a fully transposed transmission line
1. positive, negative and zero sequence impedances are equal.
2. positive and negative sequence impedances are equal.
3. zero and positive sequence impedances are equal.
4. negative and zero sequence impedances are equal
Option 2 : positive and negative sequence impedances are equal.
## PU System and Symmetrical Components MCQ Question 8 Detailed Solution
Purpose of Transposition:
• Transmission lines are transposed to prevent interference with neighbouring telephone lines.
• The transposition arrangement of high voltage lines helps to reduce the system power loss.
• We have developed transposition system for Single circuit tower using same tension tower with reduced deviation angle.
• Transposition arrangement of power line helps to reduce the effect of inductive coupling.
• It is proved more economical Solution, in comparison of the conventional transposition system.
Important:
Transposition arrangement
The transposition arrangement of the conductor can simply show in the following the figure. The conductor in Position 1, Position 2 and Position 3 changes in a specific arrangement to reduce the effect of capacitance and the electrostatic unbalanced voltages.
Z1 = Z2 = ZS - Zm
Zo = ZS + 2Zm
Where,
Z1 = positive sequence impedance
Z2 = positive sequence impedance
Zm= mutual impedance
ZS= self impedance
Positive and negative sequence impedances are equal.
# A 2-bus system and corresponding zero sequence network are shown in the figure.The transformers T1 and T2 are connected as
Option 2 :
## PU System and Symmetrical Components MCQ Question 9 Detailed Solution
Concept:
Zero sequence networks for different 3-phase loads are shown below.
The zero sequence equivalent circuits of 3-phase transformers can be drawn by using the following general circuit.
Z is the zero-sequence impedance of the windings of the transformer. These are two series and two shunt switches. One series and one shunt switches are for both sides(primary and secondary) separately.
The series switch of a particular side is closed if it is star grounded and the shunt switch is closed if that side is delta connected, otherwise, they are left open.
Application:
Given two bus system,
The zero-sequence network of the corresponding transformers will be
# The per unit impedance of a synchronous machine is 0.242. If base voltage is increased by 1.1 times, then per unit value will be:
1. 0.266
2. 0.242
3. 0.220
4. 0.200
Option 4 : 0.200
## PU System and Symmetrical Components MCQ Question 10 Detailed Solution
Concept:
The relation between new per-unit value & old per unit value impedance
$${({Z_{pu}})_{new}}\; = {({Z_{pu}})_{old}} \times {\left( {\frac{{k{V_{base}}}}{{k{V_{new}}}}} \right)^2} \times \;\left( {\frac{{MV{A_{new}}}}{{MV{A_{old}}}}} \right)$$
Also $${Z_{pu}} = \frac{{{Z_{Actual}}}}{{{Z_{base}}}}$$
$${Z_{base}} = \frac{{kV_{base}^2}}{{MV{A_{base}}}}$$
Where,
(Zpu)new = New per unit value of impedance
(Zpu)old = Old per unit value of impedance
kVbase = Old base value of voltage
kVnew = New base value of voltage
MVAnew = New base value of power
MVAold = Old base value of power
Calculation:
When the voltage bases is increased by 1.1 times (i.e. kVnew = 1.1kVbase), the new per unit impedance is
$$(Z_{pu})_{new}=0.242\times \frac{1}{1.1^2}=0.2\ \ pu$$
# A 500 MVA, 11KV synchronous generator has 0.2 p.u. synchronous reactance. The p.u. synchronous reactance on the base values of 100 MVA and 22 KV is
1. 0.16
2. 0.01
3. 4.0
4. 0.25
Option 2 : 0.01
## PU System and Symmetrical Components MCQ Question 11 Detailed Solution
Concept:
The relation between new per-unit value & old per unit value of reactance
$${({X_{pu}})_{new}}\; = {({X_{pu}})_{old}} \times {\left( {\frac{{k{V_{base}}}}{{k{V_{new}}}}} \right)^2} \times \;\left( {\frac{{MV{A_{new}}}}{{MV{A_{old}}}}} \right)$$
Also $${X_{pu}} = \frac{{{X_{Actual}}}}{{{X_{base}}}}$$
$${X_{base}} = \frac{{kV_{base}^2}}{{MV{A_{base}}}}$$
Where,
(Xpu)new = New per unit value of reactance
(Xpu)old = Old per unit value of reactance
kVbase = Old base value of voltage
kVnew = New base value of voltage
MVAnew = New base value of power
MVAold = Old base value of power
Calculation:
Given that,
Xd(old) = 0.2 pu
MVA(new) = 100
MVA(old) = 500
KV(old) = 11
KV(new) = 22
∴ $${X_{d\left( {new} \right)}} = 0.2 \times \frac{{100}}{{500}} \times {\left( {\frac{{11}}{{22}}} \right)^2} = 0.01\;pu$$
# The characteristic impedance of free space is
1. 397 Ω
2. 367 Ω
3. 387 Ω
4. 377 Ω
Option 4 : 377 Ω
## PU System and Symmetrical Components MCQ Question 12 Detailed Solution
Concept:
The characteristic impedance of a wave travelling in a lossy medium is given by
$$Z = \sqrt {\frac{{j\omega μ }}{{\sigma + j\omega ϵ}}}$$
Put σ = 0 (free space and lossless medium)
$$Z = \sqrt {\frac{μ_0 }{ϵ_0}}$$
Where,
μ0 = Permeability of free space = 4π x 10-7 H / m
ϵ0 = Permittivity of free space = 8.85 x 10-12 F/m
Calculation:
$$Z = \sqrt {\frac{4\pi \times10^{-7} }{8.85 \times10^{-12}}}$$
∴ Z = 377 Ω
# In case of an unbalanced star-connected load supplied from an unbalanced 3-phase 3-wire system, load current will consist of:
1. only +ve sequence component
2. only –ve sequence component
3. only zero sequence component
4. both +ve and –ve sequence component
Option 4 : both +ve and –ve sequence component
## PU System and Symmetrical Components MCQ Question 13 Detailed Solution
Unbalanced star load supplied from the unbalanced three-phase three-wire system.
• Line voltage and load current will consist of only positive and negative sequence components but not zero sequence components.
• Load voltage or phase voltage will consist of positive, negative and zero sequence components.
Positive sequence component: It is a balanced three-phase set having phase sequence as of the original phasor.
Negative sequence component: It is a balanced three-phase set having phase sequence opposite to original phasor.
Zero sequence component: It is the set of three phasors equal in magnitude and all three phasors are in phase.
# The pu parameters for a 300 MVA machine on its own base are inertia M = 10 pu and reactance X = 4 pu. The pu values of inertia and reactance on 50 MVA common base, respectively, will be:
1. 60, 0.67
2. 40, 0.67
3. 60, 0.4
4. 4, 10
Option 1 : 60, 0.67
## PU System and Symmetrical Components MCQ Question 14 Detailed Solution
Given that, pu parameters for a 300 MVA machine on its own base
Inertia: Mold = 10 pu
Reactance: Xold = 4 pu
New base = 50 MVA
New pu value of inertia,
$${M_{Pu\;new}} = {M_{Pu\;old}} \times \frac{{{{\left( {MVA} \right)}_{old}}}}{{{{\left( {MVA} \right)}_{new}}}}$$
$$\Rightarrow \;{M_{Pu\;new}} = 10 \times \frac{{300}}{{50}} = 60\;Pu$$
New pu value of reactance,
$${X_{Pu\;new}} = {X_{Pu\;old}} \times \frac{{{z_{Base\;old}}}}{{{Z_{Base\;new}}}}$$
$$\Rightarrow {Z_{Base}} = \frac{{{{\left( {kV} \right)}^2}}}{{MVA}}$$
$$\Rightarrow {X_{Pu\;new}} = {X_{Pu\;old}} \times \frac{{{{\left( {MVA} \right)}_{new}}}}{{{{\left( {MVA} \right)}_{old}}}} \times \frac{{\left( {kV} \right)_{old}^2}}{{\left( {kV} \right)_{new}^2}}$$
Now (kV)old = (kV)new [not given]
$$\Rightarrow {X_{Pu\;new}} = 4 \times \frac{{50}}{{300}} = 0.67\;Pu$$
Note:
We know that Pu value depends on the base value of that quantity hence the actual value of that quantity is always equal-
pu value old = actual/old base
Now, new pu value = actual/new base
⇒ Puold × Base old = Punew × Basenew
⇒ pu new = (pu old × old base)/(new base)
# The per unit impedance of a synchronous machine is 0.242. If the base voltage is increased by 1.1 times, then the per unit impedance will be:
1. 1.0
2. 0.6
3. 0.8
4. 0.2
Option 4 : 0.2
## PU System and Symmetrical Components MCQ Question 15 Detailed Solution
Concept:
$${\left( {{{\rm{Z}}_{{\rm{pu}}}}} \right)_{{\rm{new}}}} = {\left( {{{\rm{Z}}_{{\rm{pu}}}}} \right)_{{\rm{old}}}} \times {\left[ {\frac{{{{\left( {{\rm{K}}{{\rm{V}}_{{\rm{base}}}}} \right)}_{{\rm{old}}}}}}{{{{\left( {{\rm{K}}{{\rm{V}}_{{\rm{base}}}}} \right)}_{{\rm{new}}}}}}} \right]^2}{\rm{\;}}$$
Calculation:
$${\left( {{{\rm{Z}}_{{\rm{pu}}}}} \right)_{{\rm{old}}}} = 0.242$$
$${\left( {{\rm{K}}{{\rm{V}}_{{\rm{base}}}}} \right)_{{\rm{old}}}} = 1$$
$${\left( {{\rm{K}}{{\rm{V}}_{{\rm{base}}}}} \right)_{{\rm{new}}}} = 1.1$$
$${\left( {{{\rm{Z}}_{{\rm{pu}}}}} \right)_{{\rm{new}}}} = 0.242 \times {\left[ {\frac{1}{{1.1}}} \right]^2} = 0.2{\rm{\;}}$$
# The zero sequence component of the unbalanced system of vector VA, VB and VC is ______ of their vector sum.
1. one-third
2. one-fourth
3. half
4. two-third
Option 1 : one-third
## PU System and Symmetrical Components MCQ Question 16 Detailed Solution
Fortescue’s theorem:
According to Fortescue’s theorem, any unbalance system can be resolved into balance the system of three components namely zero sequence component, positive sequence component, and negative sequence component.
Va = Va0 + Va1 + Va2
Vb = Vb0 + Vb1 + Vb2
Vc = Vc0 + Vc1 + Vc2
α = 1 ∠120°, α2 = 1 ∠240°, α3 = 1 ∠0°
1 + α + α2 = 0
Any phasor multiply by α operator rotates anticlockwise 120°.
Va = Va0 + Va1 + Va2
Vb = Vb0 + Vb1 + Vb2 = Va0 + α2Va1 + αVa2
Vc = Vc0 + Vc1 + Vc2 = Va0 + αVa1 + α2Va2
$$\left[ {\begin{array}{*{20}{c}} {{V_a}}\\ {{V_b}}\\ {{V_c}} \end{array}} \right] = \left[ {\begin{array}{*{20}{c}} 1&1&1\\ 1&{{\alpha ^2}}&\alpha \\ 1&\alpha &{{\alpha ^2}} \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {{V_{a0}}}\\ {{V_{a1}}}\\ {{V_{a2}}} \end{array}} \right]$$
$$[{\left[ V \right]_{abc}} = \underbrace {\left[ A \right]}_{Symmetrical\;component\;of\;Transfer\;matrix}{\left[ V \right]_{012}}$$
[V]012 = [A]-1[V]abc
$$\left[ {\begin{array}{*{20}{c}} {{V_{a0}}}\\ {{V_{a1}}}\\ {{V_{a2}}} \end{array}} \right] = \frac{1}{3}\left[ {\begin{array}{*{20}{c}} 1&1&1\\ 1&\alpha &{{\alpha ^2}}\\ 1&{{\alpha ^2}}&\alpha \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {{V_a}}\\ {{V_b}}\\ {{V_c}} \end{array}} \right]$$
$${V_{ab}} = \frac{1}{3}\left[ {{V_a} + {V_b} + {V_c}} \right]$$
Zero sequence component, $${V_{a0}} = \frac{1}{3}\left[ {{V_a} + {V_b} + {V_c}} \right]$$
Positive sequence component, $${V_{a1}} = \frac{1}{3}\left[ {{V_a} + \alpha {V_b} + {\alpha ^2}{V_c}} \right]$$
Negative sequence component, $${V_{a2}} = \frac{1}{3}\left[ {{V_a} + {\alpha ^2}{V_b} + \alpha {V_c}} \right]$$
Hence, the zero-sequence component of the unbalanced system of vector $$\overrightarrow {{V_A}} ,\;\overrightarrow {{V_B}} ,\;\overrightarrow {{V_C}}$$ is $${\frac{1}{3}^{rd}}$$ of their vector sum.
# What will be the p.u current if the actual current is 200 amps and base current is 20 amps?
1. 200 p.u
2. 10 p.u
3. 4000 p.u
4. 20 p.u
Option 2 : 10 p.u
## PU System and Symmetrical Components MCQ Question 17 Detailed Solution
Concept:
Per Unit System:
• The per-unit value of any quantity is defined as the ratio of actual value in any unit to the base or reference value in the same unit.
• Any quantity is converted into per unit quantity by dividing the numeral value by the chosen base value of the same dimension.
• The per-unit value is dimensionless.
$$P.U. = \frac{{{A_V}}}{{{B_V}}}$$
Where
AV = Actual value
BV = Base value of quantity
Explanation:
Given
Actual Current = 200 A
Base Current = 20 A
P.U. Current = $$\frac{{200}}{{20}}$$
P.U. Current = 10
# Per unit impedance is equal to
1. base impedance / actual impedance
2. actual impedance / base impedance
3. base MVA / base current
4. base current / base MVA
Option 2 : actual impedance / base impedance
## PU System and Symmetrical Components MCQ Question 18 Detailed Solution
Per unit value of a quantity is defined as the ratio of its actual value to its base value.
Per unit impedance = actual impedance / base impedance
Important Point:
The relation between new per-unit value & old per unit value impedance
$${({Z_{pu}})_{new}}\; = {({Z_{pu}})_{old}} \times {\left( {\frac{{k{V_{base}}}}{{k{V_{new}}}}} \right)^2} \times \;\left( {\frac{{MV{A_{new}}}}{{MV{A_{old}}}}} \right)$$
Also $${Z_{pu}} = \frac{{{Z_{Actual}}}}{{{Z_{base}}}}$$
$${Z_{base}} = \frac{{kV_{base}^2}}{{MV{A_{base}}}}$$
Where,
(Zpu)new = New per unit value of impedance
(Zpu)old = Old per unit value of impedance
kVbase = Old base value of voltage
kVnew = New base value of voltage
MVAnew = New base value of power
MVAold = Old base value of power
# A 25 MVA, 33 kV transformer has a pu impedance of 0.9. The pu impedance at a new base 50 MVA at 11 kV would be
1. 10.4
2. 12.2
3. 14.4
4. 16.2
Option 4 : 16.2
## PU System and Symmetrical Components MCQ Question 19 Detailed Solution
25 MVA, 33 kV transformer – Zpu old = 0.9, MVAold = 25 MVA, Vold = 33 kV
At new base, Pnew = 50 MVA, Vnew = 11kV
$${Z_{pu\;new}} = {Z_{pu\;old\;}} \cdot \left( {\frac{{MV{A_{new}}}}{{MV{A_{old}}}}} \right) \cdot {\left( {\frac{{{V_{old}}}}{{{V_{new}}}}} \right)^2}$$
As Zpu = Z/Zbase
$$\Rightarrow {Z_{pu\;new}} = 0.9\left( {\frac{{50\;MVA}}{{25\;MVA}}} \right){\left( {\frac{{33\;kV}}{{11\;kV}}} \right)^2}$$
= 0.9 × 2 × 9
Zpu new = 16.2 pu
# The line current flowing in the lines toward a balanced load connected in delta are Ia = 100∠0°, Ib = 141.4∠225°, Ic = 100∠90°. Find the symmetrical component of the line current.
1. Ia0 = 0.07∠115°, Ia1 = 121∠150°, Ia2 = 209.88∠5°
2. Ia0 = 7∠125°, Ia1 = 211∠125°, Ia2 = 229.88∠150°
3. Ia0 = 0.007∠45°, Ia1 = 111∠15°, Ia2 = 29.88∠105°
4. Ia0 = 0.7∠145°, Ia1 = 131∠105°, Ia2 = 290.88∠10°
Option 3 : Ia0 = 0.007∠45°, Ia1 = 111∠15°, Ia2 = 29.88∠105°
## PU System and Symmetrical Components MCQ Question 20 Detailed Solution
Concept:
The relation between the line currents in terms of the symmetrical components of currents is given below.
$$\left[ {\begin{array}{*{20}{c}} {{I_a}}\\ {{I_b}}\\ {{I_c}} \end{array}} \right] = \left[ {\begin{array}{*{20}{c}} 1&1&1\\ 1&{{a^2}}&a\\ 1&a&{{a^2}} \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {{I_{a0}}}\\ {{I_{a1}}}\\ {{I_{a2}}} \end{array}} \right]$$
$$\left[ {\begin{array}{*{20}{c}} {{I_{a0}}}\\ {{I_{a1}}}\\ {{I_{a2}}} \end{array}} \right] = \frac{1}{3}\left[ {\begin{array}{*{20}{c}} 1&1&1\\ 1&a&{{a^2}}\\ 1&{{a^2}}&a \end{array}} \right]\left[ {\begin{array}{*{20}{c}} {{I_a}}\\ {{I_b}}\\ {{I_c}} \end{array}} \right]$$
Ia0 = Zero Sequence Component of Current
Ia1 = Positive Sequence Component of Current
Ia2 = Negative Sequence Component of Current
a = 1∠120°, which represents the rotation of 120° in clockwise direction.
a2 = 1∠-120° or 1∠240° in anticlockwise direction or in clockwise direction, respectively.
Calculation:
Ia = 100∠0°, Ib = 141.4∠225°, Ic = 100∠90°
Zero sequence component of current,
$${I_{a0}} = \frac{1}{3}\left( {{I_a} + {I_b} + {I_c}} \right) = \frac{1}{3}\left( {100\angle 0^\circ + 141.4\angle 225^\circ + 100\angle 90^\circ } \right)$$
$${I_{a0}} = \frac{1}{3}\left( {100\angle 0^\circ + 141\left( {{\rm{cos}}225^\circ + {\rm{i\;sin}}225^\circ } \right) + 100({\rm{cos}}90^\circ + {\rm{i\;sin}}90^\circ } \right))$$
$$\Rightarrow {I_{a0}} = \frac{1}{3}\left( {0.02 + i0.02} \right) = 0.007\angle 45^\circ$$
Positive sequence component of current,
$${I_{a1}} = \frac{1}{3}\left( {{I_a} + a{I_b} + {a^2}{I_c}} \right) = \frac{1}{3}\left( {100\angle 0^\circ + 1\angle 120^\circ \left( {141.4\angle 225^\circ } \right) + 1\angle - 120^\circ \left( {100\angle 90^\circ } \right)} \right)$$
Ia1 = 11115°
Negative sequence component of current,
$${I_{a2}} = \frac{1}{3}\left( {{I_a} + {a^2}*{I_b} + a*{I_c}} \right) = \frac{1}{3}\left( {100\angle 0^\circ + 1\angle - 120^\circ \left( {141.4\angle 225^\circ } \right) + 1\angle 120^\circ \left( {100\angle 90^\circ } \right)} \right)$$
Ia2 = 29.88∠105°
|
# Intro to Dart: Creating a Marquee
##### Tutorial Details
In this tutorial, I’ll introduce you to Dart and how to start using it. In the course of the article we’ll build a simple JavaScript-based image marquee without writing a single line of JavaScript – just Dart.
Note: This tutorial was originally published in March 2012, as a freebie for our Facebook fans. Since Activetuts+ has now shut down, we’re making it free to all readers.
## Project Preview
We will be building the following simple marquee, a screenshot of which is shown below. Click on the image to launch a working example of the project.
## Step 1: Install the Dart Editor
Let’s get started building out little marquee. From here on out, we’ll be much more hands-on, and I’ll take the time explain the new stuff along the way.
First things first; we can write Dart in any old text editor, really, but the most convenient way to get started and to immediately run your project in a browser (via JavaScript compilation) is to install the Dart Editor.
The Dart Editor is rather bare-bones. It’s built on Eclipse, and I hope that eventually it will be offered as an Eclipse plug-in for those with an existing Eclipse installation. But for now, it’s a self-contained Eclipse modification that does Dart and not much else.
It offers a few of the features that Eclipse workspaces typically offer, such as language-aware completion. The big advantage it brings, though, is a fairly simple way to start and run a Dart project.
Once the download completes, extract the ZIP file and you’ll have a dart folder. You can place this wherever you like; I’ve moved mine to my Applications folder.
## Step 2: Create a Dart Project
Let’s open up the Dart Editor application. You’ll find it just inside that dart folder you just unzipped.
Once it launches, you’ll be presented with a “Welcome” page, which provides a jumping-off point to some sample projects. These are certainly worth taking a look, but we’ll skip past them for now and first get a little more familiar with the language.
Go to the File menu and choose New Application… or click on the top-left icon in the toolbar:
In the resulting window, enter a name for the project (I’m using DartMarquee). It will want to store the project in a folder named dart in your home directory, but you can change that by clicking on the Browse… button. Note that whichever folder you choose, Dart Editor will create a new folder in the selected folder, using the name you’ve given for the project. Inside of that there will be a few files created for you, also using the name of the project you supplied.
Also be sure the “Web Application” is selected, not “Server Application.”
## Step 3: Run the Hello World Example
The default project created for you is a simple Hello World example. You may as well see what happens before we start building our (slightly) more complicated project. Run the application by either choosing Tools > Run from the menu, pressing Command-R (Mac) or Control-R (PC), or by clicking on the green “play” button in the tool bar:
You may expect this open up in your default browser, but – surprise! – Google’s Chromium browser will open (not to be confused with Chrome; Chromium has a blue-ish monochrome icon, not Chrome’s colorful icon). Chromium has built-in support the the Dart language.
This is not the process I mentioned earlier where Dart files are compiled into JavaScript; this is the Dart VM running regular Dart code, which is cool, but not terribly useful for those of us currently building JavaScript applications. We’ll make the project compile to JavaScript next.
## Step 4: Add a JavaScript Launch
If you change the run settings, then we can get Dart to compile to JavaScript. To change these settings, choose the Tools > Manage Launches… menu, press Command-Shift-M (Mac) or Control-Shift-M (PC), or click and hold the downward arrow next to the Run tool bar button, and choose Manage Launches… from the pop-up menu.
In the window that appears, you’ll see the default launch created for you, which has the Chromium icon. To create a new launch, click on the new document icon, which will display a pop-up menu.
Choose Dart Web Launch from the menu. In the top field at the right, give it a meaningful name, like DartMarquee JS or something to designate that we’re going for a JavaScript rendition in another browser.
Under Launch Target, click Browse… next to HTML file:. A window will open that presents all (one) HTML files present in your project. Click on DartMarquee.html and then click OK.
Under Browser you can choose to leave the default checked, or uncheck that option and then specify a browser with the Select… button. The browser choice shouldn’t matter too much, although I will be using some CSS3 tricks so a modern browser would be ideal.
Click Apply and then Close.
Now run the project again, but this time be sure to do it by clicking and holding on the Run tool bar button, and then selecting your new launch target. You should now get the same Hello World application in the browser of your choosing, which will be using JavaScript compiled from Dart. In fact, you’ll see a new file show up in your file list: DartMarquee.dart.js. This is the compiled JavaScript file.
Now that you’ve run the new launch once, future Runs will remember this decision and launch the JavaScript version.
But we’re not done yet. The HTML file is set up to include the Dart file, along with another JavaScript file that interprets Dart files in the browser (which is super-cool, but not the best for production applications). We need to edit the HTML file to use the compiled JavaScript file, not the Dart files.
## Step 5: The HTML
Your new project should open with DartMaquee.dart in the main editor area. We’ll get to that soon enough, but let’s get our HTML page set up. Double-click on DartMarquee.html in the file list on the left, and it will open in a new tab in the editor.
Dart Editor is really only aware of the Dart language, which is too bad. You’ll notice that the HTML file opens without any syntax coloring or intelligence about the language. It’s good enough for our purposes now, but feel free to open this file (and any other non-Dart file) in the text editor of your choosing. We won’t be spending too much time in non-Dart files, so I’ll just be editing them in Dart Editor for this tutorial.
The body markup is not what we want, but first let’s update those <script> tags as mentioned in the last step. You can delete the first <script> tag altogether; that’s the once that includes the Dart file directly. Delete this line:
<script src="http://dart.googlecode.com/svn/branches/bleeding_edge/dart/client/dart.js"></script>
(Hint: line numbers aren’t enabled by default, but that’s one of the few options available under Preferences).
The script is the in-browser runtime for Dart; one pretty nifty feature is that you can write Dart without compiling it to JavaScript, and have browsers run it anyway. You just need to include dart.js. Of course, this makes for some extra overhead and impacts performance. Pretty cool trick, though.
Now let’s change the remaining <script> tag to load our compiled JavaScript file. Change this:
<script type="application/dart" src="DartMarquee.dart"></script>
To this:
<script src="DartMarquee.dart.js"></script>
If you like, run the project again, and use the developer tool to ensure that the JavaScript file is loading, and the other two are not.
Now, change that <h2> tag into a <div>, and give it an id of marquee.
<div id="marquee"></div>
You can leave the <h1> if you like; sometimes it’s nice to have page identification.
Finally, we need to link to a CSS file (which we’ll create in the next step). In the <head> add a <link> tag:
<link rel="stylesheet" href="DartMarquee.css">
The application will not work, because we’ve removed the <h2> that was targeted by the Dart code, not to mention that we still need a CSS file. Let’s do that next.
## Step 6: The CSS
We’ve linked to a non-existent CSS file, so let’s address that. In the Files area of Dart Editor, right-click, and choose New File: from the menu (you can also find New File… in the File menu).
In the resulting window, you may need to ensure that the DartMarquee project is selected in the middle area. Then enter DartMarquee.css for the file name, and click on Finish.
This file will be ready to edit in the main editor area, but as with HTML files, CSS files aren’t intelligently supported with syntax by Dart Editor. Feel free to do your CSS editing in your preferred text editor. Or, since we’re really not here to delve into the CSS, just copy and paste form below into Dart Editor:
#marquee {
width: 600px;
height: 400px;
background-color: #111;
}
.mainImage {
height: 300px;
background-color: #666;
position: relative;
}
.mainImage img {
display: block;
position:absolute;
left: 0px;
top: 0px;
-webkit-transition: opacity 0.6s ease-out;
-moz-transition: opacity 0.6s ease-out;
-ms-transition: opacity 0.6s ease-out;
-o-transition: opacity 0.6s ease-out;
transition: opacity 0.6s ease-out;
}
opacity: 0;
}
.thumbContainer {
height: 100px;
background-color: #DDD;
}
.button {
width: 100px;
height: 100px;
background-color: #eee;
position: relative;
float: left;
}
.button .border {
width: 90px;
height: 90px;
position: absolute;
opacity: 0;
border: 5px solid orange;
-webkit-transition: opacity 0.3s ease-out;
-moz-transition: opacity 0.3s ease-out;
-ms-transition: opacity 0.3s ease-out;
-o-transition: opacity 0.3s ease-out;
transition: opacity 0.3s ease-out;
cursor: pointer;
}
.button:hover .border {
opacity: .5;
}
.button.selected .border {
opacity: 1;
}
Again, we’re not here to discuss CSS. I’ll point out that I’m using CSS3 transitions for the button hovers and the main image changes. Otherwise, it should be fairly straightforward.
Run the project one more time, or simply reload from the browser; at this point there won’t be any JavaScript to re-compile. If you run from Dart Editor, be sure to switch back to the HTML or Dart file; Dart Editor doesn’t know what to do when you “Run” from a CSS file.
You should see a large dark rectangle. Doesn’t look like much yet, but you’re on the right tack.
## Step 7: Preparing the Images
One more housekeeping task, and that’s to make our images readily accessible, so that we can see them when we’re ready to write that code.
In the download package, you’ll find a folder named images. Copy or move this folder from the download archive to your project folder, so that’s sitting at the same level as your other files. You’ll probably need to use the Finder/Explorer for this task, as Dart Editor doesn’t (yet) support importing or drag-and-drop of existing files. They’ll show up in your file list once you get them in place, though.
Now we can get into some Dart code. That’s next!
## Step 8: The main() Function
Open up the DartMarquee.dart file in the editor. You’ll see three main blocks of code:
The third block is the main function, and this is a required part of your Dart project. Dart will look for this function as an entry point to execution. Contrast this with JavaScript where scripts are simply executed from top to bottom. You can certainly replicate this methodology in JavaScript, but the key difference is that you don’t have to, and if you do you have to call main() yourself; in Dart, it’s expected that you have the main function, as it will be called for you once Dart in ready to begin execution of your application.
This won’t be a foreign concept to you if you’ve programmed in C or Java, or even in ActionScript 3 and used the Document class. The nice thing about it is that there is a standardized, expected place to begin the execution of your code.
## Step 9: Classes
Dart brings with it proper classes, which you may end up preferring to JavaScript’s class-ish-ness prototype system. Take a look at the second block of code in DartMarquee.dart. This is the meat of the program right now, and is a class with two methods declared. We’ll be ditching a large part of this code. We’ll get into the syntax as we go, but for now, hollow out this class so that it looks like this:
class DartMarquee {
DartMarquee() {
}
}
What this leaves is the class declaration and the constructor. The class declaration begins with class, which is followed by the name of the class. That this class is named DartMarquee is purely a function of the template used in the application creation process in DartEditor. It’s important to know that just because this file is named “DartMarquee.dart” does not mean that there has to be a class name DartMarquee inside. We’re not going to change it, because it makes sense, but Dart is like PHP or Ruby in that you can put as many class definitions as you like in a single file, and the naming doesn’t need to match the file name (as it does in ActionScript).
The class definition is then contained between the curly braces. Inside of that, we have a constructor. This is a function that is run when a new object is instantiated from this class. Typically one puts set-up code in a constructor. Note that the name of the constructor needs to match the name of the class, otherwise it’s not a constructor, and is a regular method instead.
Everything else you add to a class should go in between the two curly braces denoting the class.
You’ll notice that back in the main function, a DartMarquee object is instantiate with this line:
new DartMarquee().run();
This should look like object-oriented JavaScript. The .run() then calls the run method on the newly-created object. We just removed that method, so go ahead and change that line to this:
new DartMarquee();
## Step 10: Imports
Something I’m pretty excited about with Dart, as someone coming from JavaScript, is the ability to easily import and use other code into your project. The first block of our default code uses a single import statement:
#import('dart:html');
This imports a built-in Dart library, one that deals specifically with HTML pages and giving us access to DOM manipulation functionality. We’ll be importing other libraries as we need them, including one that we’ll write ourselves.
When our Dart project is compiled to JavaScript, all of the disparate Dart code is converted and concatenated into a single JavaScript file. It’s smart enough to not include the same library twice, so you can import libraries from other files and not worry about them conflicting with or duplicating code in the final product.
Our DartMarquee.dart file should look something like this now:
#import('dart:html');
class DartMarquee {
DartMarquee() {
}
}
function main() {
new DartMarquee();
}
## Step 11: Add a Property to the Class
Let’s finally write code. We’re going to add a target property to the DartMarquee class, so that the main HTML element that we’re referencing is handy within the class.
Just after the class declaration, and before the constructor, add a property like so:
class DartMarquee {
Element _target;
DartMarquee() {
}
}
Notice the syntax here: instead of var, we use a datatype to both declare a variable and give it a datatype all at once. This syntax is reminiscent of C and Java. The name of our property is _target, and the line ends with a semi-colon. You’ll find Dart much less forgiving about missing semi-colons.
An interesting thing about Dart type system is that it’s optional. If you specify a type, Dart will do what it can to adhere to typing rules. But we could also opt to leave typing off by writing that property like this:
var _target;
Dart will then not attempt to keep your types safe; you’ll have a dynamically-typed variable just like in JavaScript. What’s even more interesting than the fact that it’s optional is that you can mix strong and dynamic typing in the same code.
Personally, strong typing is one of the things that draws me to Dart, as it’s helpful to have that kind of accountability. This will be the last time I mention dynamic typing in Dart.
We’re not done with that property yet. This is an important property, so let’s set it in the constructor.
class DartMarquee {
Element _target;
DartMarquee(this._target) {
}
}
This may look a little unexpected. This is a Dart idiom; it’s so common for a constructor to receive arguments, and then simply use the constructor’s body to stash those values into properties, that Google created a shortcut.
Normally, a method parameter looks like you’d expect it to: any variable name will do, but not something that looks like a property on another object. These parameters are normal parameters like you’re used to; they’re available by name within the body of the method.
This new syntax, however, will go ahead and assign the value passed in to this parameter to the property designated by the parameter name. In other words, the code above is identical to this code:
DartMarquee(target) {
this._target = target;
}
Only we don’t have to write that boilerplate of a line.
Note that this shortcut is only available in constructors.
## Step 12: DOM Queries
Now that we have a target property set up, we need to give it a value. Back in the main function, we need to select the marquee <div> and pass it in to the constructor.
Dart provides a method to find HTML elements by CSS selection, much like jQuery or any of the popular JavaScript libraries do. This is provided by that dart:html library imported at the top of the file, which also provides a top-level document variable which gives us global access to the HTML document.
Update the main function to look like this:
void main() {
new DartMarquee(document.query('#marquee'));
}
It’s that simple: if you’ve used jQuery (or another library), this should be rather familiar. Simply call document.query and pass in the selector. Dart does the rest.
## Step 13: Console Logging
If you’ve developed with JavaScript, chances are you’ve made heavy use of console.log to test and verify your code. Dart provides a print function that, when compiled to JavaScript, turns in to a call to console.log. Let’s try it out, and test our project so far at the same time.
In the DartMarquee constructor, let’s print the _target property to make sure it’s being set.
DartMarquee(this._target) {
print(this._target);
}
And hit Run. In your browser, open up your console and you should see something like this:
Note that at the time of this writing, there is a bug with the Dart Editor that generates a warning stating that “print” is not a method. This is being tracked by Google and will probably be fixed soon, if not by the time you read this. But if you’re seeing that warning, just ignore it; it still compiles fine. This is an example of the bleeding edge on which Dart stands; the print warning was not happening when I started writing this tutorial, it’s only happened with the most recent build of the Editor (build 5104).
## Step 14: DOM Manipulation
We’re going to create the needed HTML elements programmatically, and place them within our target <div>. Dart provides a very clean API for this kind of task.
First, let’s create a few more properties to hold some of the elements. Add these right below the first property you added:
class DartMarquee {
Element _target;
DivElement _mainImage;
DivElement _thumbContainer;
DartMarquee(this._target) {
Notice how we’re using underscores as a prefix? Not only this a common convention when naming private properties, it’s actually idiomatic Dart. An underscore prefix makes the property (or method, or class even) private. Otherwise, it’s public.
Also notice how we’ve typed them as DivElement? Another nice feature of Dart (as least for the web) is that it provides classes for the individual HTML elements, unlike the more generic approach usually taken in JavaScript. The upshot is that individual element types have the appropriate properties so it’s easy to manipulate them with Dart. For example, ImageElements have a src property that can be safely and easily accessed directly with Dart to modify the image’s source.
Now let’s create those elements. In the constructor:
DartMarquee(this._target) {
_mainImage = new Element.tag('div');
_mainImage.classes = ["mainImage"];
_thumbContainer = new Element.tag('div');
_thumbContainer.classes = ["thumbContainer"];
}
There’s a lot going on here; let’s break it down.
First we create a new DivElement. But notice that we don’t write new DivElement as you might expect (and believe me, I expected that, and continued to expect that for quite a while before I discovered the proper technique). Even though DivElement is a class, it doesn’t have a constructor that you can access. Instead, you use a named constructor on the Element class to create an element of a specific type.
Named constructors are just different constructors (kind of like method overloading, but it’s not really that) that can provide a different interface to the construction. In this case, we can specify by string the type of element. You can also write new Element.html('<div>...</div>'); to write out the HTML in string format. Two rather different approaches, so we have two constructors.
Once we have our _mainImage DivElement, we set its class. Element provides a classes property which lets us access the various classes that may applied. In this case, it’s a brand new element, so that property is empty. We set it to a single class name, "mainImage".
You might expect classes to be an Array (or List, in Dart parlance), but it’s actually a Set. A Set is similar to an Array in that it’s a collection of independent values, but the key difference is that the collection is unordered; there is no guarantee that the order of the contained values will be anything in particular, or even the same each time. This has a slight ramification in how we work with the classes property, but for now it’s a simple assignment to what looks like an Array containing a single String.
The next two lines are repeated almost verbatim, except that we’re assigning the _thumbContainer property, and assigning a different class.
The final two lines add these new Elements to the DOM, specifically, to the target div. As you can see, there is a nodes property on the Element, which as you’d expect is a List of child elements. Being a List (or Array), we can simply add (similar to JavaScript’s push) an Element into it. And at this point, the elements are in the DOM.
Go ahead and run the project again; because we’ve added classes to the new <div>s, and we have our CSS file ready to go, you should see a slight change to the page:
We need some content, not just grey boxes at which to look. We’ll drive our little marquee with a JSON file, so let’s look at how we make an HTTP request in Dart.
First, let’s create the JSON file. It’ll be pretty simple, and shouldn’t need any explaining in and of itself. Create a new file in your Dart project (File > New File…) and name it marquee.json. Add the following content:
{
"images":[
"scottwills_machinery3.jpg",
"scottwills_machinery4.jpg",
"scottwills_machinery5.jpg",
"scottwills_machinery6.jpg",
"scottwills_machinery7.jpg",
"scottwills_machinery8.jpg"
]
}
Save, and turn back to DartMarquee.dart. We’ll add the code to load this file in the constructor, after we’ve created our extra Elements.
XMLHttpRequest request = new XMLHttpRequest();
String url = 'marquee.json';
request.open("GET", url, true);
request.send();
And that’s how you do that.
Oh, all right, a little explanation. First, we create an XMLHttpRequest object. That will handle the loading of the data (and would also handle the sending of data if we were doing that sort of thing). The next line is a bit superfluous, but I wanted to show another variable being created. Notice that String types can be created with the quote literal, just like in JavaScript (and just about every other language). In Dart, there is no difference between single- and double-quotes, unlike PHP or Ruby.
Next we start working with the XMLHttpRequest object. First we open the connection, passing in the method ("GET"), the url we just created, and finally that we’re interested in an asynchronous request (true). That means that we need to add an event listener to know when the load completes. That brings us to the most interesting line:
request.on.load.add(onJSONLoad);
This is Dart’s event model. Objects that dispatch events have an on property which acts as “event central”, where you can go to plan your next party. There will also be properties on the on object that correspond to the various events dispatched by the object in question; in this case, load is one of the events. Each of these event properties is actually a collection of listeners, to which we can add a new listener (onJSONLoad in this case; this hasn’t been written yet in case you were wondering).
This syntax took a little getting used to, but now I really like it. It’s safer and cleaner than request.addEventListener('load', onJSONLoad), wouldn’t you agree?
The last line of our previous code block simply sets the request in motion; send it off to get our data.
For this to work, we need an onJSONLoad function. Let’s start doing that next.
## Step 16: Methods and Event Listeners
Now we get to write a new method. This method also happens to be an event listener (for the XMLHttpRequest we set up in the last step), but regardless the syntax is the same. Find a spot in the DartMarquee class that’s after the close of the constructor but before the close of the class – it should be between two closing braces. Add the following:
void onJSONLoad(Event e) {
}
The syntax should be fairly obvious. It follows the property/variable syntax, in that we’ve replaced JavaScript’s function keyword with a datatype. The datatype is the type of the value returned by the function. In this case, void is actually the lack of type, as the function doesn’t return anything. And similar to properties, you can optionally leave the method untyped and use the function keyword instead of a type.
Now we can try out the application. Run it again, and check the console. You should get the message that our function has run, meaning the JSON file has loaded.
## Step 17: Properly Bound “this”
Let’s pause in the action for a moment to talk theory. Don’t worry, you’ll learn something important along the way.
In the code that we just wrote to add an event listener, our event listener is properly bound to the scope of the object it belongs to. In JavaScript, this be bound to the object that dispatched the event. That is, if you write this in JavaScript:
myElement.addEventListener('click', onClick);
function onClick() { console.log(this); }
Then this refers to myElement, the object doing the event dispatching. In Dart, however, this will refer to the object to which the listener belongs. Try it out; change the print to this:
void onJSONLoad(Event e) {
print(this);
}
And run it again. You should see this:
OK, that doesn’t exactly prove things very well. [object Object] could be anything. Let’s take a quick look at a useful trick for making your classes describe themselves.
Add a method to DartMarquee called toString. This method should return a String and take no arguments.
String toString() {
return "DartMarquee";
}
Run it one more time and now you end up with this:
This should illustrate that “this” refers to the DartMarquee object. JavaScript does not behave this way without workarounds. This means that you don’t have to worry about binding functions to their scope when adding event listeners, such as with jQuery’s bind method and other similar solutions.
## Step 18: Generics
Let’s move on and parse our JSON now that the JSON file is loaded. We’re going to parse it and stuff those URLs into a property, so first let’s trot back to the top of the class and add a _urls property:
Element _target;
DivElement _mainImage;
DivElement _thumbContainer;
List<String> _urls;
This syntax will look odd if you’re not coming from Java. The variable name is _urls, and the datatype is List<String>. We could just write List _urls, and that would work, but we can also take advantage of something that Dart provides. Back towards the beginning, I described reified generics, and the <String> part of the datatype is the generic. That is, the elements within the List are typed as Strings. The point of this step is pretty much to introduce this syntax. We’ll see it again soon.
If you’ve programmed ActionScript 3, you’ll find the syntax similar to Vectors, and in fact Dart Lists and AS3 Vectors are essentially the same thing.
## Step 19: Parsing JSON
Now let’s get to parsing. Remove the print statement from onJSONLoad and add this:
void onJSONLoad(Event e) {
XMLHttpRequest request = e.target;
Map<String, Object> result = JSON.parse(request.responseText);
print("JSON: " + result);
int i = 0;
_urls = result['images'];
_urls.forEach((url) {
print("url $i:$url");
i++;
});
}
This code really isn’t so bad. Here’s how it breaks down.
Line 2: This is just casting the source of the event (found in e.target) to an XMLHttpRequest so we can more safely work with properties on it.
Line 3: This one gets a little gnarly. Skip to the second half of the line. We’re getting responseText out of the XMLHttpRequest object, which gives us the raw text found in our file. And we pass that into the parse method of the JSON class. That’s all there is to parsing JSON; it’s essentially built-in! Now, to make sure we can work with the data, we need to store it in a variable. This variable is result. Because I’m advocating strong typing, it also has a type. This type is Map<String, Object>, which might be a little frightening.
A Map is basically what we call an Object in JavaScript; it’s a collection, and stores its values by a String key.
Because Map is a collection, it can be generified (see last step), but because there are technically two things we can specify (the key and the value), we supply two types. Somewhat oddly, you can’t use anything other than String for the key type, so I’m not sure why it needs specified. It may be possible that Dart eventually allows the use of any type as the key. But for now, it’s a String key. Because our JSON data is an Object at it’s outermost, we specify Object as the value type. We have a little flexibility, depending on the JSON structure.
Line 4: Now that we have our JSON parsed, let’s just print it out to verify the result.
Line 5: Initialize a counter. Note that Dart supports an int type.
Line 6: Get the images property out of the main JSON object, which should be an Array/List, and store that in our _urls property that we set up in the last step.
Line 7: Loop over that List, using forEach and an anonymous function. Note the syntax for anonymous functions: (url) {...}. If there is no return type, we can leave it off completely and just start with the parameter list. It feels a little odd at first, but ultimately leads to less code written, which is kind of nice.
Line 8: Now we can print out the URL along with its index. Here we can see that Dart has String interpolation, which lets you expand variables within a String, and avoid breaking out of a String in order to include the value of a variable. The use of the dollar sign indicates that what follows is actually a variable, and Dart should interpolate it. Again, this is less code written and leads to much more readable code than String concatenation.
Line 9: Hopefully this line of code doesn’t need explanation.
Run the application, and…uh oh. That console doesn’t look pretty.
## Step 20: Importing More Libraries
The fix is, thankfully, rather simple. Dart is structured into libraries, and it turns out that JSON capability isn’t part of the HTML library. We simply need to add the following line at the very top of the file:
#import('dart:json');
Run the project again, and you should get a console full of output:
What I find odd is that this seems like something the JavaScript compiler catches, but it’s only a warning. The compiler recognizes that you’re using a class called JSON but doesn’t know where to find that class…that seems like an important thing to catch. The lesson here, aside from where the JSON library is, is to check the Problems panel in Dart Editor. It got kind of buried amidst the false print warnings, but it was there:
Also, when you run the project, the Console panel takes over in that space, so you may have missed the warnings altogether. Just something to be on the look out for. This kind of thing will probably improve with time.
## Step 21: Writing External Classes
As we continue to explore Dart’s capabilities, we’re going to write a new class to handle a single thumbnail image. We’ll ultimately instantiate a number of these, one for each thumbnail.
While it’s possible to insert a second class definition into the same file, let’s see what happens when we decide to write an external class. In Dart Editor, create a new file for our project and name it MarqueeButton.dart. You’ll be presented with the following template:
class MarqueeButton {
}
Again, there is no requirement that we name the class after the file, or vice versa, but it does make sense, so we’ll leave well enough alone and just start filling in the details.
For now, let’s just get this functional by providing a simple constructor that prints a message so we can see it working. Add a constructor to the class:
class MarqueeButton {
MarqueeButton(index, image) {
print("$index:$image");
}
}
Nothing we haven’t been over already; this is a simple constructor that uses String interpolation.
But to use it, we need to make sure the DartMarquee class is aware of the MarqueeButton class. At the top of DartMarqee, where there are two #import statement, add a third line to include our new class:
#import('dart:html');
#import('dart:json');
#source('MarqueeButton.dart');
You were expecting another #import, weren’t you? #source is a bit simpler than #import. #import is for libraries, which need to be declared as such and can link to other files. #source simply includes the targeted file. One thing to note is the #sourced files cannot, themselves, link to other files. Even #importing the built-in libraries will cause a compiler error. As such, this is a simple way to collect a few files into another script, but for more complex structures you may want to consider creating a library.
Now that we’re linking to our new class, let’s use it. Down in onJSONLoad, we’ll replace the existing print with some instantiation:
void onJSONLoad(Event e) {
XMLHttpRequest request = e.target;
Map<String, Object> result = JSON.parse(request.responseText);
print("JSON: " + result);
int i = 0;
_urls = result['images'];
_urls.forEach((url) {
MarqueeButton btn = new MarqueeButton(i, "images/thumbs/" + url);
i++;
});
}
If you run the project again, you’ll get more or less the same thing, only now it’s logging from within the MarqueeButton class.
## Step 22: Fill In the “MarqueeButton” Class
At this point, we can fill in most of the MarqueeButton class without running into much that’s new. I’ll present almost the full body of the class here, and discuss it briefly below.
class MarqueeButton {
DivElement _target;
String _image;
int _index;
Function _onClick;
MarqueeButton(this._index, this._image) {
_target = new Element.tag('div');
_target.classes = ["button"];
DivElement border = new Element.tag('div');
border.classes = ["border"];
_target.style.backgroundImage = 'url("'+_image+'")';
}
void onClick(Event e) {
_onClick(this);
}
}
We start the class off with a handful of properties, all private and typed. It may be interesting to note the Function type. We’ll get to this in a moment, but this illustrates that functions are fully-fledged objects in Dart, and can be passed around by reference rather easily.
The constructor is mostly about building up the HTML elements for the button. We start from scratch; the only things passed in to the constructor are the index of the button and the image URL. We’ve seen this before, creating and adding new elements. Line 15, however, present something new, although I’d imagine you can figure out what it does. Elements have a style property which lets you set CSS styles rather easily. The properties available to the style object follow the CSS style names, only removing the hyphen and turning the name camel-case. Note that the value might be a String or in the case of numeric values, it can just be a number.
The last line of the constructor adds a click event listener to the button, following the convention we saw with the XMLHttpRequest events.
Then we have our onClick method, the listener for that click event. For style purposes we’ll add the .selected class to the element, then we call the _onClick function. This, you’ll recall, is the property we declared earlier. This is a poor man’s event dispatching, and what happens is that DartMarquee will set this property to a function of its own, so that MarqueeButton can call it. We’ll get to the setting in a moment, and we haven’t written the relevant DartMarquee code. But because functions are first-class citizens of the Dart world, it’s easy to pass that function around, and execute it somewhat arbitrarily.
## Step 23: Setters and Getters
We’ll finish off the class with some getters and a setter. For the uninitiated, setters and getters are special functions that simply return a value (getters), or receive a value (setters). They’re common enough, and most object-oriented languages provide some method for creating implicit setters and getters, which are functions that are called as if they were properties.
Dart has this, as well, and throws some syntactic sugar on top of it, to boot. Add this to the end of the class (before the closing curly brace, but after the onClick method):
DivElement get target() => _target;
int get index() => _index;
Function get click() => _onClick;
void set click(Function fn) {
_onClick = fn;
}
You can see the sugar in the three getters. Each one follows this pattern:
Type get name() => expression;
The type is nothing new; it’s the return type of the function. The get keyword signifies that this is an implicit getter function. name() is just the name of the method. Next is the => operator, which basically says “return the value that is expressed on my right.” In the case of _target, we’re simply accessing the value stored in the _target property and returning that. In other words, a basic getter method, written with a little less code than normal.
The expression can actually get a little more complicated than that, such as a boolean check or some simple one-liner math. If it’s going to require more than one line of code, it needs to be written as a regular getter, which is just like a regular method except for the get keyword:
DivElement get target() {
return _target;
}
We’re done with the MarqueeButton class now, so we’ll turn back to the DartMarquee class and start using it.
## Step 24: Displaying Thumbnails
To display the buttons, we need to go back to the DartMarquee class and revisit the onJSONLoad method. Specifically, we need to add to that loop.
_urls.forEach((url) {
MarqueeButton btn = new MarqueeButton(i, "images/thumbs/" + url);
btn.click = onThumbClick;
i++;
});
Another nodes.add(), this time on the _thumbContainer div and adding the target of the MarqueeButton object.
Then we set the click property to a method we have yet to write, but will do so now:
void onThumbClick(MarqueeButton btn) {
print("onThumbClick");
}
We’ll work on this next, but for now we should be able to run the application, see the thumbnails, and click on them to see the log message.
We’re almost there. We’ll work on getting that click to mean something in the next two steps.
## Step 25: Handling the Click
The logic involved in displaying a larger image isn’t terribly complex, and at this point we’ve had a pretty extensive tour of the Dart language. I’ll start listing the method here, and then discuss what’s going on.
First we need two properties declared. At the top of the class, with the other properties, add these lines:
MarqueeButton _currentButton;
ImageElement _currentImage;
Then update onThumbClick:
void onThumbClick(MarqueeButton btn) {
if (_currentButton != null) {
_currentButton.target.classes.remove('selected');
}
_currentButton = btn;
ImageElement image = new Element.tag('img');
image.width = 600;
image.height = 300;
image.src = "images/" + _urls[btn.index];
}
The first thing to notice is that we’re checking for the existence of a value in _currentButton. If it does, then we remove the .selected class. Then we set the _currentButton property to the button that was clicked, for next time.
It’s worth nothing that Dart handles Booleans a little differently than you may be used to. Seth Ladd has a write-up on Booleans in Dart, in which we explains:
Dart has a true boolean type named bool, with only two values: true and false (and, I suppose, null). Due to Dart’s boolean conversion rules, all values except true are converted to false. Dart’s boolean expressions return the actual boolean result, not the last encountered value.
Therefore, when checking for the existence of a value within a variable, it’s wise to write if (variable != null) as opposed to the shorthand if (variable), as that could actually report false even through the variable has a valid value stored in it.
Next we create an image element, set its size, the src, and then add it as a child.
You should be able to try this out now. We won’t get a nice fade between the images, but you should now be able to use the marquee to switch images.
## Step 26: Working with the Transition
Let’s work on that fade. Add the highlighted code below to the onThumbClick method. Note that Line 11 is a change from how it was before (it uses insertAdjacentElement), and the lines after that are new.
void onThumbClick(MarqueeButton e) {
if (_currentButton != null) {
_currentButton.target.classes.remove('selected');
print(_currentButton.target.classes);
}
_currentButton = e;
ImageElement image = new Element.tag('img');
image.width = 600;
image.height = 300;
image.src = "images/" + _urls[e.index];
_currentImage = image;
ImageElement img = evt.target;
img.remove();
});
}
The change to line 53 introduces another way to add children elements. Element.nodes.add() is fine for appending at the end, but if we want to insert in a specific place, in this case at the beginning, then nodes doesn’t give us enough options. insertAdjacentElement does provide options, although its interface isn’t as clean as it could be. In fact, it’s lifted from the Windows Internet Explorer API. I try not to get too opinionated in a tutorial, but this is an odd decision.
Regardless, it’s the API we have if we want to do more than append to the child elements. We want to add our new image to the beginning, so we pass in "afterBegin" to insertAdjacentElement, which does exactly that. This method is documented at MSDN if you’d like a description of the various valid arguments to that parameter.
The rest of the code involves itself with the CSS3 transition; by adding a .fade_away class to the old image (after checking to be sure it’s not null) we set it’s opacity to 0, invoking the transition. Then _currentImage is set to the new image, to get set for the next transition.
Finally, another event listener is added to the current image so that when the transition happens, and is finished, we can run a bit of code. All we do is get the event target and cast it as an ImageElement (not strictly necessary, but it’s something that I find useful to do in general). Then by calling remove() on the ImageElement, we remove it from the DOM. In other words, once it fade away completely, we can remove it altogether to keep our DOM tidy.
Note also that we’re using another anonymous function as the event listener in this case. Either way would work, but since this is practically a one-line function, making it anonymous is rather convenient.
Run the application, click on one thumb to load an image, then another thumb and watch it in silent awe.
## Step 27: The Final Touch
Our Dart application is rather functional now, but you’ve probably noticed that it has one minor flaw: there is not image loaded up right away. This is a simple fix.
In Marquee.dart, find the onJSONLoad method and add the highlighted line of code toward the bottom:
void onJSONLoad(Event e) {
XMLHttpRequest request = e.target;
Map<String, Object> result = JSON.parse(request.responseText);
print("JSON: " + result);
int i = 0;
_urls = result['images'];
_urls.forEach((url) {
MarqueeButton btn = new MarqueeButton(i, "images/thumbs/" + url);
btn.click = onThumbClick;
if (i == 0) btn.onClick(null);
i++;
});
}
In effect, if we’re on the first iteration, take that MarqueeButton and call its onClick method. You’ll remember that as the event listener for the click event within the MarqueeButton. We’ll just call it directly, to sort of simulate a click on the first button, so as to trigger the setting of the styles and putting content in the right place. Since the method expects an event parameter, but isn’t really used, we can supply null to the method call to satisfy the compiler.
Run it once more, and you should now have the first image selected and ready in the main area.
## Step 28: Where To Go From Here
We’ve just scratched the surface of Dart, but the cool thing is that if you know JavaScript, you already know Dart in one sense. You’re already familiar with what you can do with an HTML page, and generally how to do it. Dart for the web doesn’t really add any capabilities or fancy frameworks, it’s just another language in the same problem domain. If you want to learn more, you can do worse than to simply write applications in Dart. Maybe dig out a smallish/simple bit of JavaScript you’ve done and port it over to Dart.
If you like scouring the web for more resources, Google is certainly your friend, although the name “Dart” can lead to many unrelated hits that are about the game of darts, rather than the language. Many times I’ve had to specify “dart language” in my searches or get a little more specific than just “dart events”. There is quite a bit of information floating around.
First, the official Dart website is at dartlang.org. You’ll find a small tutorial there that goes into some of the unique language features, along with the nifty Dartboard widget that lets your write and execute dart code in the browser you can even use the widget on your own site).
If you think you know what you need to do, just don’t know the right method name or class, the API documentation is good place to start, at api.dartlang.org. Sometimes the docs are a little bare or even wrong, but you should probably begin any quest for an answer here.
I’ve already mentioned the mailing list, located at groups.google.com/a/dartlang.org/group/misc/topics. It’s very active and I had a few questions answered in a matter of minutes there. The Google engineers are very involved on the list, as well.
The Dart site also has a pretty nice JavaScript-to-Dart comparison chart, located at synonym.dartlang.org, which takes common JavaScript code snippets and shows the equivalent Dart code right beside it.
Moving away from Google’s own resources, there are a few Dart-centric blogs that kept coming up in searches. One of the most prolific is Japh(r) by Chris Strom, at japhr.blogspot.com/search/label/dartlang, who is also writing a book on Dart.
The Dartosphere (dartosphere.org aggregates several different blogs about Dart, and can be a gold mine of information.
DartWatch, at dartwatch.com, is another Dart-centric blog that has plenty of content to keep you busy.
One problem, however, is that Dart is a bit of a moving target currently, and some of the older posts on blogs might be out-of-date by the time you get to them. Just keep that in mind. The mailing list is the best place to go if you can’t find a solution through a web search.
One last resource: if this tutorial sparks some interest amongst Tuts+ readers, then we’ll probably find a few more tutorials to write that delve deeper into the world of Dart.
## Step 29: Regarding Events
In this tutorial, we learned how to attach event listeners to object, for example:
someElement.on.click.add(myClickListener);
You may have noticed that we did not leverage this model when we needed to have the MarqueeButton object communicate to the DartMarquee object. We went for a more lo-fi event listener, where we simply pass a Function in to the object, and then call that Function from within the object. You may ask yourself, why did we do that? Why didn’t we use the on property to dispatch an event? Where does that highway lead to?
The answer is that Dart doesn’t provide this event mechanism outside of its own objects. Not only that, that event system is only available to objects in the HTML libraries. This feels like an area where Google might be able to open up. It sure would be nice to have our own classes become event dispatchers by simply extending an EventDispatcher class or similar, and with a little bit of code getting that mechanism for free.
It’s possible to build your own system that mimics the built-in mechanism, but for the purposes of this tutorial, I went the lo-fi route. There may be some future Dart tutorials that go deeper.
## Conclusion
Is Dart the future? Some say yes, some say no. I say, “I don’t know”. I’m certainly intrigued by the possibilities, and as long as it compiles to usable JavaScript today, then maybe it doesn’t matter if Dart isn’t interpreted natively by all of the browsers.
For now, I would say that if CoffeeScript is something that’s been catching on, then the Dart-to-JavaScript technique certainly has the same opportunity. Unlike CoffeeScript, though, you end up with some overhead JavaScript, which may not be appropriate for a vast majority of JavaScript-enabled web pages today. For instance, our DartMarquee project compiles into a JavaScript that’s over 100 KB. That’s a bit much for such a simple marquee. One should be able to write that in regular JavaScript, aided by jQuery or a similar library, for well under that weight limit. And the niceties provided by Dart, with classes, typing, and imports, aren’t enough for this small application to really justify the size.
But for larger applications, like Google Docs, 280 Slides, or Mockingbird, then you can very easily justify the overhead. You’ll have hundreds of KB of JavaScript anyway, so a little extra for the compilation process in exchange for a more structured set of classes will definitely appeal to some programmers.
That’s all for this introduction to Dart. Thanks for reading. I hope it was enlightening for you!
• DAvide
For me, coming from Actionscript, and wanting to dive into html5, Dart is really appealing. I hope it’ll really catch on!
Thanx for the tutorial!
• Bill D
Dru
nice work!!
• Emrah Atılkan
love to see dart as an Actionscript Developer. This language will be on the future, no doubt.
|
anonymous 3 years ago Pleaseeee help me.. What is the electric force between a +2 µC point charge and a –2 µC point charge if they are separated by a distance of 5.0 cm? (µC = 1.0 × 10–6 C)
1. anonymous
$\Huge \color{Lime}{~\:\:\:\:\:\:\:\:\:\:\:\:\frak Welcome\:\:\frak To\:\:\frak Open\frak Study}$
2. anonymous
F = Kq1q2/r^2
3. anonymous
Coulomb's Law: $F=K{q_1q_2\over d^2}$ $K = const.\\ q_1 = 2\times10^{-6}C\\ q_2= 2\times10^{-6}C\\ d=5{\rm cm}\times {1{\rm m}\over 100{\rm cm}}=0.05{\rm m}$
4. anonymous
the important thing is to have all the units in SI system
5. anonymous
So i had to put cm into m like i believe you did above?
6. anonymous
yep
7. anonymous
now from here where do I go?
8. anonymous
wouldnt q2 be negative?
9. anonymous
we plug em in the equation for the force. $F=8.99\times10^{9}\times \frac{2\times10^{-6}\times2\times10^{-6}}{(0.05)^2}$
10. anonymous
the negative sign can be neglected since we are only looking for the magnitude (i.e., the amount) of force. since the two charges are oppositely charged, the above force will be a force of attraction. this is the information we get from the charges
11. anonymous
Okay cool so then Id just plug the above into my calculator and thats the answer. right?
|
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# A bowl contains one marble labeled 0, one marble labeled 1
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A bowl contains one marble labeled 0, one marble labeled 1 [#permalink]
### Show Tags
20 May 2017, 05:39
1
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Difficulty:
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Question Stats:
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### HideShow timer Statistics
A bowl contains one marble labeled 0, one marble labeled 1, one marble labeled 2, and one marble labeled 3. The bowl contains no other objects. If two marbles are drawn randomly without replacement, what is the probability that they will add up to 3?
(A) 1/12
(B) 1/8
(C) 1/6
(D) 1/4
(E) 1/3
Source: Nova GMAT.
_________________
If you liked my post, kindly give me a Kudos. Thanks.
Math Expert
Joined: 02 Sep 2009
Posts: 52905
Re: A bowl contains one marble labeled 0, one marble labeled 1 [#permalink]
### Show Tags
20 May 2017, 05:46
1
rohan2345 wrote:
A bowl contains one marble labeled 0, one marble labeled 1, one marble labeled 2, and one marble labeled 3. The bowl contains no other objects. If two marbles are drawn randomly without replacement, what is the probability that they will add up to 3?
(A) 1/12
(B) 1/8
(C) 1/6
(D) 1/4
(E) 1/3
Source: Nova GMAT.
$$P(sum = 3) = P(0, 3) + P(1, 2) = 2*\frac{1}{4}*\frac{1}{3} + 2*\frac{1}{4}*\frac{1}{3} = \frac{1}{3}$$. We multiply by 2 in each case because (0, 3) can occur in two ways first 0, then 3 OR first 3, then 0. The same for (1, 2).
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Re: A bowl contains one marble labeled 0, one marble labeled 1 [#permalink]
### Show Tags
20 May 2017, 10:24
Probability of an event = (Number of favourable outcomes)/(Total Outcomes)
Here total outcomes = total ways of selecting (or drawing) 2 marbles out of 4
=4C2 = 4!/2!2! = 6.
Favoarble outcomes = total ways where the numbers on two marbles add up to 3
= 2 (either numbers 0 & 3 OR numbers 1 & 2)
So required probability = 2/6 = 1/3
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Joined: 10 Sep 2017
Posts: 5
Re: A bowl contains one marble labeled 0, one marble labeled 1 [#permalink]
### Show Tags
09 Apr 2018, 17:31
Bunuel wrote:
rohan2345 wrote:
A bowl contains one marble labeled 0, one marble labeled 1, one marble labeled 2, and one marble labeled 3. The bowl contains no other objects. If two marbles are drawn randomly without replacement, what is the probability that they will add up to 3?
(A) 1/12
(B) 1/8
(C) 1/6
(D) 1/4
(E) 1/3
Source: Nova GMAT.
$$P(sum = 3) = P(0, 3) + P(1, 2) = 2*\frac{1}{4}*\frac{1}{3} + 2*\frac{1}{4}*\frac{1}{3} = \frac{1}{3}$$. We multiply by 2 in each case because (0, 3) can occur in two ways first 0, then 3 OR first 3, then 0. The same for (1, 2).
2*1/4*1/3 = 1/6? How do you get 1/6 + 1/6 = 1/3?
Math Expert
Joined: 02 Sep 2009
Posts: 52905
Re: A bowl contains one marble labeled 0, one marble labeled 1 [#permalink]
### Show Tags
09 Apr 2018, 20:32
cman2010 wrote:
Bunuel wrote:
rohan2345 wrote:
A bowl contains one marble labeled 0, one marble labeled 1, one marble labeled 2, and one marble labeled 3. The bowl contains no other objects. If two marbles are drawn randomly without replacement, what is the probability that they will add up to 3?
(A) 1/12
(B) 1/8
(C) 1/6
(D) 1/4
(E) 1/3
Source: Nova GMAT.
$$P(sum = 3) = P(0, 3) + P(1, 2) = 2*\frac{1}{4}*\frac{1}{3} + 2*\frac{1}{4}*\frac{1}{3} = \frac{1}{3}$$. We multiply by 2 in each case because (0, 3) can occur in two ways first 0, then 3 OR first 3, then 0. The same for (1, 2).
2*1/4*1/3 = 1/6? How do you get 1/6 + 1/6 = 1/3?
_________________
Re: A bowl contains one marble labeled 0, one marble labeled 1 [#permalink] 09 Apr 2018, 20:32
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# Union and Intersection Calculator
By Maciej Kowalski, PhD candidate
Last updated: Jun 17, 2021
Welcome to Omni's union and intersection calculator, where we'll learn how to find `A∪B` and `A∩B`, i.e., `A` union `B` and `A` intersection `B`. Obviously, apart from learning the symbols for set operations, we'll formally define the union and intersection of sets to see what the difference is. In short, it all boils to whether we want the elements to be in any of the sets or all of them. Still, the comparison of union vs. intersection deserves its very own section, which we further support with some union and intersection examples.
## Union and intersection of sets and their symbols
Before we move to operations, let's see the formal set definition.
💡 A set is a collection of distinct elements.
Observe how general the concept is. In particular:
We often want to compare two or more sets: see which elements belong to one and not the other, or which are common to both. This takes us to set operations. There are quite a few of those, but you've visited us to see the union and intersection calculator, so we'll focus on those two.
💡 The union of two sets is the set containing all elements that belong to at least one of the initial sets. The math union symbol is `∪`, i.e., we read `A∪B` as `A` union `B` or the union of `A` and `B`.
💡 The intersection of two sets is the set containing all elements that belong to both the first and the second set. The math intersection sign is `∩`, i.e., we read `A∩B` as `A` intersection `B` or the intersection of `A` and `B`.
Alright, we've defined the union and intersection formally, but let's maybe spare a few sentences to translate them to everyday language. However, it so happens that it's helpful to study the concepts by comparing the similarities and differences between the union and intersection of sets.
## Union vs. intersection
Before we see some union and intersection examples, let's try to understand the two operations by contrasting them. For that, below, we've defined the union and intersection again, but using everyday language.
The union of sets `A` and `B` gathers all elements that fall in `A`, in `B`, or in both. As such, it's always larger than or equal to either of the two (i.e., it's a superset of both).
On the other hand, the intersection of sets `A` and `B` gathers elements common to both, i.e., all that fall both in `A` and in `B`. As such, it's always smaller than or equal to either of the two (i.e., it's a subset of both).
In particular, the intersection always lives inside the union. What is more, they are equal if and only if the two underlying sets are equal. And to explain the differences some more, let's see what happens if one of the sets is wholly contained in the other. Then, according to the explanation above:
• `A` union `B` is the larger of the two; and
• `A` intersection `B` is the smaller of the two.
Furthermore, observe that it doesn't really matter in what order we take the sets: `A∪B` is the same as `B∪A`, and `A∩B` is the same as `B∩A`. In math, we call this property the commutativity of the union and intersection of sets.
As a matter of fact, the two operations have more properties in common. For instance, even though we've defined the union and intersection of only two sets, we can easily extend it to more. To be precise, `A₁∪A₂∪A₃∪...∪Aₙ` and `A₁∩A₂∩A₃∩...∩Aₙ` simply denote the collections of elements belonging to, respectively, any and all of the listed sets. In fact, this notation makes sense because both operations satisfy the associative property:
• `A∪(B∪C) = (A∪B)∪C`
• `A∩(B∩C) = (A∩B)∩C`
At this point, you may feel that the union and intersection of sets are quite similar to the two basic arithmetic operations: addition and multiplication. Indeed, scientists often refer to the union symbol as sum and to the intersection sign as product.
The similarities may help you wonder if we have here an equivalent of another arithmetic law: the distributive property of multiplication over addition. And indeed we do! What is more, while with numbers, it only works one way (i.e., multiplication over addition), in set theory, it works both ways: union over intersection and intersection over union.
• `A∪(B∩C) = (A∪B)∩(A∪C)`
• `A∩(B∪C) = (A∩B)∪(A∩C)`
Note how we used brackets to make sure we don't mix the two operations.
Lastly, let us mention that the comparison of union vs. intersection is best portrayed by so-called Venn diagrams. They are graphic representations using circles or ellipses for each of the sets, with the shapes intersecting to show which elements are common and which are not.
Don't worry; we'll see a proper number-based diagram very soon, along with an implementation of all the above theory to practice: it's time for union and intersection examples!
## Example: using the union and intersection calculator
Suppose that Amy and Mark want to lose some weight after the pandemic lockdowns and restrictions. Besides taking special care of their diet, they decide to take up a physical activity; it's just a matter of choosing the right one.
Amy likes jogging, cycling, dancing, swimming, and basketball. On the other hand, Mark enjoys dancing, tennis, soccer, and cycling. Let's use Omni's union and intersection calculator to find what the couple may like.
To begin with, our tool (like any other calculator) prefers numbers. Therefore, let us translate all the activities listed above to consecutive integers:
• `1` for jogging;
• `2` for cycling;
• `3` for dancing;
• `4` for swimming;
• `5` for basketball;
• `6` for tennis; and
• `7` for soccer.
Looking at the union and intersection calculator, we see that first, we need to tell the tool what we're dealing with. For that, we select `2` under "Number of sets" (since we have two people) and "individual entries" under "Input form" (since we'll list the activities one by one).
That'll trigger two sections underneath: one for set `A` and one for set `B`. There, respectively, we input the numbers corresponding to the activities that Amy and Mark enjoy, so in the first, we input:
• `1`, `2`, `3`, `4`, `5`,
and in the second, we write:
• `3`, `6`, `7`, `2`.
(Note how, initially, the union and intersection calculator shows only three variable fields in each section. However, new ones appear once you begin inputting the values. In total, you can have sets with up to ten elements each.)
Once you give the last entry, the union and intersection calculator will spit out the answer underneath. There, we'll see:
• The elements exclusive to `A` (i.e., those that Amy likes, but Mark doesn't);
• The elements exclusive to `B` (i.e., those that Mark likes, but Amy doesn't);
• `A` union `B` (i.e., activities that at least one of them likes); and
• `A` intersection `B` (i.e., activities that both of them like).
However, before we reveal the answer, let's find it ourselves. Recall Venn diagrams from the above section: we'll draw one to illustrate the union and intersection of the sets in question.
If we put Amy's interests in a yellow circle and Marks in a red one, we'll get something like this:
From the picture, it's now easy to read the union and intersection of the sets:
• Amy likes jogging, swimming, and basketball, but Mark doesn't;
• Mark likes tennis and soccer, but Amy doesn't;
• At least one of them likes jogging, swimming, basketball, cycling, dancing, tennis, and soccer; and
• Both of them like cycling and dancing.
And just in case you'd like to see the diagram with the integers corresponding to the activities, there it is:
Make sure to experiment with Omni's union and intersection calculator to discover all its functionalities. In particular, check out the variant using interval notation, i.e., the infinite subsets of the number line.
## FAQ
### What is the difference between union and intersection?
On the one hand, the union gathers all the elements occurring in at least one of the sets. As such, all of them are its subsets. For example, the union of two sets with one entirely contained in the other is equal to the larger one.
On the other hand, the intersection gathers all the elements common to each and every one of the sets. As such, it's a subset of each of them. For instance, the intersection of two sets with one entirely contained in the other is equal to the smaller one.
### How do I find the union and intersection of intervals?
To find the union and intersection of two intervals, you need to:
1. Draw the number line.
2. Mark the endpoints of the first interval.
3. Color the line between those points.
4. Mark the endpoints of the second interval.
5. Color the line between those points using a different color.
6. The left endpoint of:
• The union is the leftmost of the left interval endpoints; and
• The intersection is the rightmost of the left interval endpoints.
7. The right endpoint of:
• The union is the rightmost of the right interval endpoints; and
• The intersection is the leftmost of the right interval endpoints.
8. For the intersection, if the left endpoint is larger, the intersection is empty.
9. Mark the endpoints as open or closed, depending on the initial data.
### How do I find the union and intersection of two sets?
To find the union and intersection of two sets, you need to:
1. List all elements from the first set.
2. Add the elements from the second set.
3. Cross out any repetitions (i.e., leave one copy of each).
4. For every element, check if it's in the sets:
• The union gathers those that appear in at least one; and
• The intersection gathers those that appear in both.
5. Enjoy having found the union and intersection of two sets.
### Are the union and intersection operations distributive?
Yes. In other words, for any sets `A`, `B`, and `C`, we have:
• `A∪(B∩C) = (A∪B)∩(A∪C)`
• `A∩(B∪C) = (A∩B)∪(A∩C)`
### Are the union and intersection operations commutative?
Yes. In other words, for any two sets `A` and `B`, we have:
• `A∪B = B∪A`
• `A∩B = B∩A`
Maciej Kowalski, PhD candidate
Number of sets
2
Input form
Individual entries
Set A
Entry #1
Entry #2
Entry #3
Set B
Entry #1
Entry #2
Entry #3
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# A steric gate controls P/E hybrid-state formation of tRNA on the ribosome
## Abstract
The ribosome is a biomolecular machine that undergoes multiple large-scale structural rearrangements during protein elongation. Here, we focus on a conformational rearrangement during translocation, known as P/E hybrid-state formation. Using a model that explicitly represents all non-hydrogen atoms, we simulated more than 120 spontaneous transitions, where the tRNA molecule is displaced between the P and E sites of the large subunit. In addition to predicting a free-energy landscape that is consistent with previous experimental observations, the simulations reveal how a six-residue gate-like region can limit P/E formation, where sub-angstrom structural perturbations lead to an order-of-magnitude change in kinetics. Thus, this precisely defined set of residues represents a novel target that may be used to control functional dynamics in bacterial ribosomes. This theoretical analysis establishes a direct relationship between ribosome structure and large-scale dynamics, and it suggests how next-generation experiments may precisely dissect the energetics of hybrid formation on the ribosome.
## Introduction
The bacterial ribosome is a massive (~2.5 MDa) ribonucleoprotein assembly that undergoes large-scale (>50 Å) rearrangements in order to translate messenger RNA (mRNA) sequences into proteins1,2,3. The biological complex is composed of three ribosomal RNA molecules and more than 50 proteins, which arrange to form the large (50S) and small (30S) subunits (Fig. 1). Each cycle of elongation begins with the delivery of an aminoacyl-tRNA (aa-tRNA) molecule to the ribosome by elongation factor Tu. After initial association with the ribosome, the aa-tRNA fully binds the ribosomal A site, a process known as accommodation4. This allows a new peptide bond to be formed, after which rotation of the 30S body5,6 facilitates the adoption of hybrid conformations7,8,9, where individual tRNAs are displaced between binding sites on the large subunit. Additional rotation10,11 and tilting12 of the 30S head can then guide the tRNA and mRNA as they move along the 30S subunit (i.e. translocation). Translocation leads to a vacant A site, which enables the ribosome to read the next mRNA codon. With the central role of protein synthesis in the cell, each of these conformational steps must be precisely regulated in order to ensure accurate and efficient expression of the genome.
Experimental studies have provided countless insights into the structure5,6,10,11,13,14,15,16,17,18, timing8,19,20,21,22,23 and kinetics24,25 of hybrid-state formation and translocation. Translocation involves movement of two tRNA molecules from the A/A–P/P (pre-translocation; Fig. 1a) to P/P–E/E (post-translocation; Supplementary Fig. 1) conformations. The notation N/M refers to a tRNA molecule that is bound to the N (=A, P, or E) site of the small subunit and M site of the large subunit. In order for translocation to occur, the P-site tRNA molecule must first transiently form a hybrid P/E configuration6,7, where the anticodon stem loop (ASL) remains bound to the P site of the small subunit, while the acceptor arm and 3′-CCA end associate with the E-site of the large subunit (Fig. 1b). In addition to a ~20 Å displacement of the tRNA elbow and a ~40 Å displacement of the 3′-CCA end, reaching the P/E conformation is associated with counterclockwise rotation (6–10°) of the 30S body domain, relative to the 50S subunit5. Subsequently16,26, or perhaps simultaneously27, the A-site tRNA adopts A/P-like hybrid configurations9,28, where it contacts the A site of the small subunit and P site of the large subunit. The tRNA molecules then proceed to the P/P–E/E conformation, which completes the translocation process.
Even though computational and experimental approaches have advanced significantly over the last decade, the transition states that control P/E formation kinetics have yet to be precisely identified. This gap represents an opportunity for energy landscape techniques to help reveal the interactions that shape the underlying free-energy barriers, and therefore control the biological kinetics. The power of energy landscape approaches is exemplified by applications to biomolecular folding, where comparison of theory and experiments has provided an understanding of the physical principles that govern dynamics29,30,31,32,33. Inspired by successes in folding, landscape approaches have been adopted to study a range of biological phenomena, including assembly34, chromatin remodeling35 and cell motility36, as well as ribosome dynamics16,37. With ever-increasing computing capabilities and the development of novel theoretical models, it is also now possible for simulations to partition the energetic contributions of steric/entropic factors38, electrostatic interactions39, and chemical steps40,41 in the ribosome.
In the current study, we use energy landscape concepts and molecular simulations, in order to identify structural elements of the ribosome that can limit the kinetics of tRNA hybrid-state formation. Specifically, we evaluated the extent to which the steric composition of the ribosome contributes to the free-energy barriers that separate P/P and P/E conformations of tRNA (Fig. 1). To address this, we applied an all-atom structure-based (i.e. Gō-like) model42 to simulate spontaneous and reversible transitions of tRNA between the P and E sites of the large subunit (Fig. 2a). Despite the simplicity of the energetic model, where the pre-translocation and post-translocation configurations are explicitly defined to be stable, we find that the structure of the ribosome predisposes tRNA molecules to adopt distinct intermediates. Analysis of the associated transition state ensembles reveals the presence of a gate-like region on the large subunit that can control the rate-limiting step during hybrid rearrangements. Additional calculations demonstrate that, due to the position of the steric barrier, the kinetics of P/E formation only depends weakly on the position of the A-site tRNA. The existence of a pronounced sterically-induced barrier highlights the intimate relationship between biomolecular structure and kinetics, while also suggesting strategies for gaining precise control of ribosome dynamics.
## Results
### Simulating spontaneous and reversible P/E hybrid rearrangements
To determine whether specific structural features (e.g. helices/loops) of the ribosome are likely to regulate the kinetics of hybrid-state formation, we simulated the ribosome using an all-atom structure-based model42,43. With this model, we observed over 120 spontaneous transitions, where the tRNA molecule moves between the P and E sites of the large subunit, while the small subunit maintains a rotated orientation. Interconversion events were initially identified by measuring the distance of the 3′-CCA end of the tRNA from the two binding sites (RP, RE; see “Methods” section and Supplementary Figs. 2 and 3 for definitions). Large (~40 Å) anti-correlated changes in RP and RE (Fig. 2a) occur when the 3′-CCA end dissociates from the P (E) site and associates with the E (P) site. In addition, the tRNA elbow is displaced by ~20 Å, as measured by RFRET (distance between residues labeled in typical single-molecule experiments27; see “Methods” section and Supplementary Fig. 4 for definition). In contrast to previous simulations of P/E dynamics, which have applied sub-microsecond explicit-solvent simulations44, or have included artificial-targeting forces45, the current study describes complete and spontaneous transitions of tRNA between the P and E sites of the large subunit. Accordingly, the presented simulations provide an opportunity to directly connect specific tRNA–ribosome interactions with the energetics of large-scale barrier-crossing events.
In order to properly interpret the simulated dynamics, it is necessary to consider some features of the employed model (i.e. the force field, or potential energy function). First, by explicitly representing all non-hydrogen atoms, it is possible to identify free-energy barriers and intermediates that are induced by the steric composition of the ribosome38. Next, the endpoints of translocation (classical P/P and E/E configurations) are explicitly defined as potential energy minima. Since known structures define the force field, one typically refers to this representation as an all-atom "structure-based” model42,43. This type of model implicitly accounts for the cumulative effect of all (direct and indirect) interactions that stabilize the endpoints, such that it describes the effective energetics of a system35,46,47. Similar to studies of proteins48, A/P hybrid formation49 and tRNA–mRNA translocation12, the multi-basin character of the model is ensured by defining every bonded and non-bonded interaction to stabilize the pre-translocation or post-translocation configuration. While the positions of the minima are pre-defined, the depths are not intended to be precise. Accordingly, the free-energy difference between the endpoints, which is determined by the binding-site interaction strength, should be considered an adjustable parameter. Further, since the current simulations describe hybrid formation events when the rRNA is restrained to a rotated orientation, translocation of mRNA is not observed. However, previous simulations with a structure-based model, where the rRNA was not restrained, have been applied to describe the relationship between tRNA–mRNA translocation and rotation12. Finally, in the current implementation of the model, spontaneous A/P formation is precluded by defining all A-site tRNA interactions to stabilize the A/A conformation. This allows us to focus on the isolated movement of the P-site tRNA, which is consistent with experimental measurements that indicate P/E formation and A/P formation may occur sequentially15,26,27. In support of this simplification, we later show that the A-site tRNA position has a minimal effect on the implicated rate-limiting step during P/E formation. When considering the above features and limitations of the model, our immediate objective is to use the simulated events to characterize the roles of sterics and structural perturbations on the energy landscape of tRNA. Through this, we aim to identify structural "hot spots” that may be responsible for controlling the kinetics of P/E formation.
### Ribosome structure leads to multiple intermediates
We find that the structural characteristics of intermediates predicted by our model are consistent with various experimentally-identified features of hybrid formation. As inferred through biochemical measurements8, in simulations of an unrotated (ϕ ≈ 0°. Angle defined in ref. 12) ribosome the tRNA molecule remains bound to the P site of the large subunit. In this case, the tRNA–tRNA elbow distance (RFRET) is consistent with crystallographic structures of the A/A–P/P conformation (Supplementary Fig. 5). In contrast, when the rRNA is restrained to a rotated orientation (TI$${\,}^{{\rm{pre}}}$$ conformation of ref. 10, ϕ ~ 7°), the tRNA molecule spontaneously and reversibly transits between the P and E sites of the large subunit (Fig. 2a). The tRNA molecule is found to frequently sample the E site, while the P site is only rarely sampled, which highlights the significant influence of subunit rotation on tRNA position. The ability of tRNA to spontaneously adopt P/E-like configurations in the absence of EF-G was shown in early biochemical studies7, whereas the reversible character of the simulated transitions is consistent with a range of single-molecule measurements19,27,50,51. While these features of the simulated dynamics are similar to phenomenological observations in experiments, there is no clear consensus on the precise (energetic) relationship between intraribosomal rearrangements and tRNA motion. For example, while various single-molecule studies27,50,51 implicate a dependence of P/E formation on conformational events within the rotation, others have suggested tRNA molecules are not tightly coupled to ribosomal components20. To varying degrees, the presented results are consistent with both perspectives. That is, we find the P/E conformation is only accessed when the ribosome is rotated and that rotation disfavors tRNA binding of the P site. However, when the subunit is rotated, the flexibility of tRNA is sufficient to allow for reversible sampling of both the P and E sites of the large subunit. Even though tRNA flexibility could allow for P-site binding in a rotated ribosome, this is not expected to occur under typical elongation conditions, as this would likely be sterically occluded by an A/P-like tRNA molecule (see later discussion). Nonetheless, these observations suggest that the relationship between rotation and tRNA position may appropriately be described in terms of a population shift mechanism, where rotation favors the P/E ensemble.
Upon further comparison of the dynamics when the small subunit is either rotated, or unrotated, we find three dominant P-site tRNA elbow positions are accessible. The apparent population of three distinct tRNA–tRNA elbow distances is consistent with the single-molecule measurements of Munro et al.27, though it should be noted that other studies only reported two states19,50,51, suggesting the number of detected states may be influenced by various factors (e.g. buffer conditions, time resolution and/or the placement of the fluorophores). When three states were detected, they were interpreted as describing a ~20 Å displacement of the P-site tRNA, followed by (or concomitant with) a ~10 Å displacement of the A-site tRNA. In our simulations, when the ribosome is unrotated, the tRNA molecules maintain an A/A–P/P configuration, where the mean value of RFRET is ~43 Å (Supplementary Fig. 5). In contrast, when the small subunit is restrained to a rotated orientation, the distribution of RFRET exhibits two pronounced peaks at 55 Å and 65 Å (Supplementary Fig. 6b). Thus, while the experiments were interpreted as signifying movement of both the A-site and P-site tRNA molecules, our analysis shows that three distinct ensembles may arise from isolated movement of the P-site tRNA. However, as discussed in later sections, the experimental signals are also compatible with rearrangements in both tRNA molecules.
In addition to corroborating inferences based on biochemical and single-molecule measurements, the simulations implicate intermediate conformations that are similar to cryoelectron microscopy (cryo-EM) reconstructions. That is, the two-dimensional free energy F(RPRE) reveals the presence of possible intermediate minima that may be encountered during P/E formation (labeled I1, I2 and NE in Fig. 2b, see Supplementary Note 1 for summary of structural nomenclature). The I1 ensemble is composed of configurations in which the tRNA elbow and 3′-CCA end are dissociated from, but remain near, the ribosomal P site (Fig. 2d and Supplementary Fig. 7). In the I2 ensemble, the tRNA elbow adopts a P/E-like position (Supplementary Fig. 7), while the 3′-CCA end samples configurations proximal to the E site (Fig. 2e). For completeness, we will note that there is also weak sampling of P/P-like configurations (labeled P/P′). This ensemble is minimally sampled when the ribosome is rotated, and it is only accessible when the A-site tRNA is in an A/A conformation. However, displacement of the 3′-CCA end of the A-site tRNA to the P site (G2251) would result in a steric clash with the P/P′ ensemble configurations. Since A-site tRNA 3′-CCA end movement is likely associated with peptide bond formation, and therefore release of the P site by the P-site tRNA, P/P′ configurations are not expected to be realized during elongation. Accordingly, we will not consider the P/P′ ensemble in subsequent analysis. While we exclude P/P′ from further consideration, the apparent intermediates (I1 and I2) suggest hybrid formation involves initial dissociation of the 3′-CCA end from the P site, followed by a large-scale displacement of the tRNA elbow and arm, and then binding to the E site. This sequence of events is qualitatively consistent with the cryo-EM study of reverse translocation by Fischer et al.15. Specifically, our I1 ensemble is similar to a structural model of the Pre-2 configuration44, where the 3′-CCA end is dissociated from the P site and the elbow is displaced in the direction of the E site, while the acceptor arm is near A2255 (G2255 in TT; Supplementary Fig. 8). In addition, I2 is similar to a structural model of the Pre-3 configuration44, where the elbow and arm are in P/E-like positions, while the 3′-CCA tail is near the E site (Supplementary Fig. 9). Finally, the Pre-4 structure and P/E ensemble correspond to conventional hybrid configurations, where the 3′-CCA end is interacting with the E site. Our model also implicates the presence of an additional free-energy minimum (NE), where the tRNA elbow is in a P/E-like position (Supplementary Fig. 7) and the 3′-CCA end is distal to both the P and E sites (Supplementary Fig. 10). However, as described below, analysis of the kinetics suggests the NE ensemble is typically reached after P/E formation has completed.
Interestingly, cryo-EM models of the ribosome in complex with release factors (RF) have revealed a tRNA conformation (Structure III52,53) that is similar to our identified I1 ensemble (Supplementary Fig. 11). While the I1 conformation is shifted, due to a higher degree of head and body rotation than in the RF models, C72 and A73 of all three tRNAs are positioned near G2255 of the 23S rRNA. Since the molecular components of these systems differ (tRNAfMet with RF vs. tRNAPhe in simulations), the similar positioning of the tRNA molecules is consistent with ribosomal sterics being a major determinant of tRNA conformation. Taken together, the range of similarities between the simulated dynamics and single-molecule/cryo-EM measurements suggests that a minimal set of physical properties can give rise to the complex dynamics that have been observed in experiments.
### Rate-limiting free-energy barrier is sterically induced
A motivation for applying energy landscape techniques is to identify the molecular factors that govern biological dynamics. To provide such insights for P/E formation, we first determined which conformational substep is rate-limiting in the simulations and then compared the associated rates with experimental measurements. As described below, this analysis provides evidence that steric interactions likely govern the transition state and kinetics of P/E formation.
To identify the rate-limiting step in the simulations, we calculated the relative rates of interconversion between the I1, I2, P/E, and NE ensembles (see “Methods” section and Supplementary Fig. 12 for definitions). As described above, since the P/P′ ensemble is not expected to be accessible under typical elongation conditions, it will not be analyzed further. That is, while this configuration is occasionally sampled when the A-site tRNA is in an A/A conformation, it will be sterically occluded once the 3′-CCA end of the A-site tRNA binds the P site (G2251) of the large subunit. In the simulations, there were numerous (>20) spontaneous (and reversible) transitions between the following ensembles: I1:I2, I2:P/E, I2:NE, and NE:P/E (Supplementary Table 1). These considerations suggest the kinetic model shown in Fig. 3 for describing the dynamics. In this kinetic scheme, “P/P” signifies a classical tRNA in an unrotated ribosome. Thus, the effective rate k1 represents the initiation of P/E formation, where there is a combination of subunit rotation and release of the P-site tRNA from the P site. However, since the current simulation did not directly study the rotation process, k1 cannot be extracted from the current data set. After P/E formation is initiated and the tRNA has reached the I1 ensemble, it may proceed directly from I2 to P/E, or pass through the NE intermediate. While NE could represent an en-route intermediate, we find that k3 ≈ 1000k4, suggesting the NE path is not kinetically competitive. In addition, k−5 ≈ 15k4, indicating that it is more probable for tRNA to adopt the P/E configuration prior to reaching the NE ensemble. Since the NE ensemble is either off-route, or it is sampled after the completion of hybrid-formation, we conclude that the I1–I2 transition (k2) is the rate-limiting step in the simulations, where $${k}_{2}\approx \frac{{k}_{3}}{200}$$.
Consistent with the slow rates of interconversion between the I1 and I2 intermediates, we find that the steric composition of the ribosome introduces a pronounced free-energy barrier (Fig. 4). Since structurally-inspired reaction coordinates for the ribosome typically provide inaccurate measures of free-energy barriers and transition states54,55, we applied transition path (TP) analysis56,57 to identify a coordinate that is suitable for studying the I1–I2 transition (see “Methods” section for details). Specifically, we used ρ1,2, which is defined as a linear combination of two interatomic distances: 0.4r3 + 0.6r75. ri is the distance between O3′ atoms of residue i in the P-site tRNA and C67 in the A-site tRNA (Fig. 4b). 123 interconversion events were detected along ρ1,2 and the calculated free-energy barrier was 3–4kBT (Fig. 4a). Free-energy barriers were recalculated using 1/5 of the simulated data to verify robustness (Supplementary Fig. 13).
We next asked whether the apparent free-energy barrier arises from steric effects, or from the competition of stabilizing interactions with the P and E sites of the large subunit. For this, we calculated the number of stabilizing P-site or E-site interactions that were formed, as functions of the tRNA position. A contact was defined as being "formed” if the atom pair is within 1.2 times the distance found in the respective endpoint conformation (P/P or E/E). In the TSE region (ρ1,2 ≈ 57 Å), nearly every P-site and E-site contact is broken. Specifically, the probability of forming any given stabilizing E-site contact is <0.02, except for one contact that has a probability of 0.047. Similarly, the probability of forming a stabilizing P-site contact is <0.02 for all interactions, except two contacts that have probabilities of 0.039 and 0.57. The single high-probability contact is with H69, and it maintains a probability of about 0.5 when in the P/P and P/E ensembles. Accordingly, the general lack of energetically stabilizing contacts in the TSE indicates that the barrier separating the I1 and I2 ensembles may be directly attributed to steric interactions between the tRNA molecule and ribosome. With regards to model parameters, this indicates that an increase in the strength of P/P and E/E stabilizing contacts would reduce the free energies of the I1 and I2 ensembles, while leaving the TSE minimally affected. Since the binding site contacts are more accessible in the I1/I2 ensembles than the TSE, changes in their strength would primarily alter the intermediate ensembles. Accordingly, increasing affinity of tRNA for the ribosomal-binding sites would amplify the existing sterically-induced free-energy barrier. Based on these considerations, the kinetics of the I1-to-I2 transition implicated by our sterics-centric model should be considered a lower-bound.
Consistent with experimentally measured rates, we find that our sterics-centric model implicates millisecond timescales for P/E formation. Using a barrier-crossing attempt frequency estimated from explicit-solvent simulations, the calculated free-energy barrier corresponds to a crossing time of ~0.2–0.5 ms. Specifically, Fig. 5 (panel f) of ref. 58 estimates the prefactor as ≈0.1–0.2/μs for a barrier of 4kBT, which corresponds to a timescale of ~0.5 ms. This is consistent with explicit-solvent simulations44 that have predicted transitions between I1 (Pre-2) and I2 (Pre-3) occur on timescales greater than microseconds. Experimentally, rapid kinetic assays have also estimated the timescale of transitions between P/P and P/E conformations to be ~30 ms26. One may partially reconcile the longer experimental timescale by noting that the calculated timescale is likely underestimated by a factor of ≈2, even though TP analysis was applied54. In addition, as described in the next section, sub-Å changes to ribosome sterics can decrease the rate by a factor of 12–15. Thus, minor structural fluctuations that may arise from experimental conditions (e.g. buffer, temperature) could account for an order-of-magnitude difference in rates. Together, these two considerations suggest the sterically-induced barrier imposes a lower-bound on the timescale of ≈10 ms. As a note, single-molecule experiments typically report longer timescales (200 ms–1 s)19,27,50,51, suggesting experiment-specific factors may further amplify the sterically-induced barrier by several kBT. To ask whether the lack of electrostatic interactions in our model also contributes to the differences with experimental rates, we used a free-energy perturbation approach (see “Methods” section) to calculate the free energy when screened electrostatic interactions (Debye–Hückel) are included. We find that screened electrostatic do not amplify the barrier height (Supplementary Fig. 14), though a more-detailed representation would be required to fully characterize the influence of electrostatic interactions. In summary, while other conformational processes (e.g. subunit rotation and release of the P site) may also occur on relatively slow timescales, the presented calculations reveal how steric interactions, alone, can ensure that P/E formation occurs in the millisecond regime.
### Steric "gate” controls tRNA rearrangements
Since the sterics-centric model and experimental measures both implicate millisecond timescales, detailed structural analysis of the simulated events may suggest which interactions limit the kinetics of P/E formation on the ribosome. To identify interactions that are specific to the transition state (Fig. 4a), we calculated the probability that each residue in the large subunit makes a steric contact with the tRNA (defined by a cutoff distance of 4 Å). For notation, $${p}_{{i}}^{{j}}$$ denotes the probability that residue i of the ribosome is in contact with the tRNA in ensemble j (TSE defined as 56.3 Å < ρ1,2 < 58.3 Å; I1, 41 Å < ρ1,2 < 41.1 Å; I2, 72.09 Å < ρ1,2 < 72.10 Å). We then evaluated $$\Delta {p}_{{\rm{i}}}={p}_{{\rm{i}}}^{{\rm{TSE}}}-\max ({p}_{{\rm{i}}}^{{\rm{I}}1},{p}_{{\rm{i}}}^{{\rm{I}}2})$$. Positive values indicate the tRNA molecule is more likely to contact residue i in the TSE than in either of the endpoints. As expected, Δpi ≤ 0 for residues near the P and E sites. However, there are 14 residues for which Δpi > 0.1. Of these, Δpi > 0.35 for six: U2076, A2077, C2078, U2423, and A2435 of the 23S rRNA, and Asn29 of protein L33. Structurally, these residues appear to introduce a narrow passageway through which the tRNA molecule must transit in order to adopt the P/E configuration (Fig. 5a, b). While non-equilibrium targeted MD simulations have suggested the tRNA can interact with many (~100) residues in the large subunit during P/E formation45, the current analysis directly correlates formation of a small set of tRNA–ribosome contacts with the rate-limiting free-energy barrier.
Sub-angstrom changes to the steric gate can lead to an order-of-magnitude change in kinetics. To demonstrate this, we calculated the change in free energy when the excluded volume of individual residues is increased. Consistent with previous applications of this model12,49,54,59,60, the excluded volume between atoms is given by $${V}_{{\rm{ex}}}=\epsilon {\left(\frac{\sigma }{r}\right)}^{12}$$, where ϵ = 2kBT and σ = 2.1 Å (Fig. 5c). For free-energy perturbation calculations, we considered an increase in the excluded volume interaction (σ = 3.0 Å) between the tRNA and individual gate residues (U2076, A2077, C2078, U2423, A2435, and Asn29). We also calculated the change in free energy for all possible combinations of steric-gate residues. When the interactions with all six gate residues are perturbed, the free-energy barrier is increased by 2.5–2.7kBT (Fig. 5d), which corresponds to a decrease in the rate by a factor of 12–15. However, similar increases in the barrier are also obtained when only five (U2076, C2078, U2423, A2435, Asn29) or four (U2076, U2423, A2435, Asn29) residues were perturbed (Fig. 5d). When fewer than four residues are modified, the effect on the barrier height is largely attenuated. These observations indicate that the minimal constituents of the steric gate are U2076, U2423, A2435, and Asn29. Together, this set of residues introduces stringent limits on the accessible tRNA pathways during P/E formation, such that small changes in their relative positions can have dramatic effects on the kinetics. From an experimental standpoint, the presence of this constriction suggests that it may be possible to modulate P/E kinetics by mutating residues in, or near, the gate. For example, introducing a larger side chain (or insertion) at position 29 of L33 would be expected to amplify the steric composition of the gate-like region, and thereby reduce the rate of P/E formation. Similarly, it may be possible to introduce pyrimidine-to-purine substitutions in the gate-like rRNA residues, in order to contract this narrow passageway in experiments.
### Influence of the steric gate is robust to A-site tRNA position
To elucidate the possible interplay between A-site and P-site tRNA dynamics, we asked whether the predicted P/E intermediates (I1 and I2) and the associated transition state ensemble will depend on the position of the A-site tRNA. Since the simulations were constructed to probe transitions of a single tRNA between the P and E sites of the large subunit, we utilized a perturbative approach to analyze the influence of the A-site tRNA. Specifically, we aligned cryo-EM structures of ribosomes with A/P and A/P* tRNA molecules (PDB ID: 4V7C and 4V7D9, see Supplementary Note 1 for complete list of terminology/notation) to the simulated system (Fig. 6a, b). We then identified all simulated frames for which the A/P or A/P* tRNA would introduce a steric clash (two atoms within 2.5 Å) with the simulated tRNA. Frames that would encounter a steric clash were removed from the data set and the free energy was re-calculated according to $$F=-{k}_{{\mathrm{{B}}}}T\mathrm{ln}\,(P)$$. This is equivalent to performing a free-energy perturbation calculation (Eq. (4)) with a hard-sphere potential for each atom in the A-site tRNA molecule.
When the sterics of an A/P or A/P* tRNA molecule are accounted for, there is a minimal increase in the free energy of the I1 ensemble, and the pronounced barrier separating the I1 and I2 ensembles remains clearly visible (Fig. 6c). This small increase in the free energy of the I1 ensemble may be attributed to steric confinement of the P-site tRNA, similar to the predicted effects of EF-Tu59 and the L11 stalk60 during accommodation, or to the influence of molecular crowders on protein stability61. However, the minimal effect of the A-site tRNA position on the I1–I2 transition reveals that the I1 ensemble is structurally compatible with A/P and A/P* tRNA conformations (Fig. 6d). That is, since the I1 ensemble is associated with a P-site tRNA molecule that is dissociated from the P site of the large subunit, there is sufficient space for the A-site tRNA to simultaneously adopt an A/P or A/P* configuration. Accordingly, the I1–I2 transition is likely to be associated with a pronounced sterically-induced free-energy barrier, which will not strongly depend on the A-site tRNA position.
The ability of the ribosome to simultaneously accommodate the I1 ensemble and various A-site tRNA configurations has potential implications in the interpretation and development of single-molecule experiments. For example, Munro et al.27 reported three distinct FRET states (high, mid, and low FRET), which were assigned A/A–P/P, A/P*–P/E, and A/A–P/E (C, H1, and H2, Munro nomenclature) conformations. While this interpretation was motivated by contemporary structural models, our analysis indicates that the employed FRET probes have the potential to mask several sterically-accessible states/ensembles during hybrid formation. That is, there may be additional “hidden” conformations that yield indistinguishable FRET signals. For example, in the presented calculations, the distribution of RFRET values for the A/P*–I1 ensemble is peaked at 42.5 Å, while the value obtained for the A/A–P/P structure63 is 42.1 Å (Supplementary Fig. 15). Next, the distribution of RFRET values for the A/P–I1 ensemble is peaked at ~53 Å, whereas the value found in the A/P*–P/E structure is 53.3 Å (Supplementary Fig. 16). Finally, given the similar positioning of the tRNA elbow in the I2 and P/E ensembles, these two conformations are likely to report very similar FRET signals (Supplementary Fig. 7). Thus, while previously employed FRET probes identified three states, we show that these signals are consistent with seven distinct combinations of A-site and P-site tRNA conformations (A/A with P/P, A/P with I1, I2 or P/E, as well as A/P* with I1, I2, or P/E). This raises the prospect that hybrid formation may be associated with numerous parallel pathways, where novel biochemical and spectroscopic techniques (e.g. multi-color FRET) will likely be necessary to unambiguously distinguish between this expanded set of possibilities.
### Aspects of the gate-like region are bacteria-specific
Sequence analysis suggests that the gate-like region may represent a viable therapeutic target, where the excluded volume of a bound small molecule could be sufficient to halt tRNA motion in bacteria. In order to be an effective target, this region should differ in bacterial and human (cytosolic and mitochondrial) ribosomes. Recent phylogenetic analysis of rRNA sequences across kingdoms of life showed that only A2423 is positioned within a moderately variable region, in terms of structure and sequence (see Fig. 2 of ref. 62). While the other rRNA gate residues are largely conserved, the remaining gate residue, Asn29 in protein L33, is distinct from its counterparts in cytosolic and mitochondrial human ribosomes. Structure alignment (Supplementary Fig. 17a) shows that L33 binds the same position in bacteria and mitochondria, and protein L36A binds a comparable position in the human cytosolic ribosome. However, the position of Asn29 in bacteria coincides with Leu37 in mitochondria, and there is not a corresponding residue at this position in L36A (Supplementary Fig. 17b, c). In addition, the immediately downstream sequence in bacteria (T. thermophilus) is Thr–Pro–Asn, while in human mitochondria it is Arg–Glu–Lys. While the backbone orientations are similar in this region, it is possible that one may be able exploit these differences in sequence to specifically target bacterial elongation kinetics.
In addition to exhibiting differences between L33 and L36A, the sequence around Asn29 is relatively conserved across bacterial species (Supplementary Fig. 18). Further, the corresponding residues in mitochondrial L33 are infrequently found in bacteria. Sequence alignment of 840 L33 proteins (Supplementary Methods) reveals that position 29 (T. thermophilus numbering) is found to be Asn in most organisms (51.5%), while the second most common residue is Thr (28.9%). Position 28 also exhibits minimal variations, where most bacteria contain Arg (66.0%) or Lys (22.3%). Position 30 was slightly more variable, where Thr (21.3%), Met (20.7%), Lys (14.0%), Asn (13.2%) and Asp (11.4%) were most common. Positions 31 and 32 were also relatively conserved, where the two most common residues at each position account for ~80% of bacterial sequences. At position 31, Pro (63.9%) and Thr (22.5%) were most common, while Glu (50.2%) and Asp (27.0%) were most frequent in position 32. Interestingly, Trp and Phe were the only residues not found within positions 28–30 for any organism, and Tyr was only found within this region in a single organism. The near-complete lack of larger residues would be expected, based on the presence of a steric gate centered at position 29. Since sub-Å changes to the gate can lead to an order-of-magnitude change in the rate, large side chains at this position would have the potential to severely impede elongation dynamics.
Overall, our analysis suggests L33 may be a suitable target for novel broad-spectrum antibiotics. That is, we find that the gate-like region satisfies some minimal requirements for such an application. First, occluding the gate-like region should impede elongation. Second, features of this region are specific to bacteria. Third, these features are common across bacterial species. While many additional factors must be considered when developing therapeutics, the current study provides a physical framework for the pursuit of a specific target that has the potential to influence elongation.
## Discussion
With continual increases in computing capacity, the development of novel theoretical models and advances in experimental techniques, the ribosome is becoming a model system for establishing general principles of biomolecular dynamics. To this end, we have focused on elucidating the influence of steric interactions on a large-scale conformational rearrangement that is essential for protein synthesis. By employing all-atom models that include a simplified description of the energetics, our calculations demonstrate how the steric composition of the ribosome imposes strict limitations on tRNA dynamics. While a complete description of the factors that control function will require models with more complete energetic representations, the current study illustrates how precisely introduced (sub-Å) perturbations to ribosome structure are sufficient to control large-scale dynamics. Specifically, our calculations demonstrate that a six-residue gate-like region can act as a modulator of hybrid-formation kinetics. This provides a concrete physical example of how ribosome structure dictates tRNA dynamics. In future studies, it will be interesting to determine whether the same structural features limit the kinetics in other organisms, and whether cellular conditions (ionic concentration, temperature, presence of co-factors/small molecules) can amplify/attenuate these structural signatures. In such endeavors, the current study will provide a quantitative foundation, upon which precise insights into complex dynamics may be obtained.
## Methods
### Structure-based model
All simulations employed an all-atom structure-based force field42, where the potential energy of the ribosome, mRNA, and tRNA molecules is defined to have minima based on the pre-translocation (PRE) and post-translocation (POST) configurations. In the PRE configuration, the ribosome is unrotated and the tRNA molecules are in the A/A–P/P conformation. The POST conformation consists of an unrotated ribosome and tRNAs in a P/P–E/E arrangement. The endpoint structures were based on a crystallographic structure of a classical ribosome with tRNA molecules in the A/A, P/P, and E/E conformations (PDB 4V6F63).
The multi-basin structure-based model was defined in several steps. First, separate single-basin all-atom structure-based models were generated for the PRE and POST complexes using the SMOG 2 software package43. In the multi-basin model, stabilizing interactions (bonds, angles, dihedrals, and contacts) corresponding to the PRE structure were assigned to the ribosome, the A-site tRNA, P-site tRNA, and mRNA molecules. We then introduced stabilizing contacts between the P-site tRNA and the E site. All tRNA–ribosome contacts defined by the POST model were included. According to this construction, the model for the P-site tRNA has multiple potential energy minima, where contacts between tRNA and both binding sites can compete to stabilize the P/P and E/E (or P/E) configurations. Various models with different weights for the P/P and E/E contacts were tested in order to produce spontaneous and reversible interconversion events between the binding sites, when the ribosome was rotated. Once parameters were selected, unrestrained simulations were performed, which showed that P/E formation is absent when the ribosome adopts an unrotated configuration (Supplementary Fig. 5).
The all-atom structure-based model explicitly represents every non-hydrogen atom. Harmonic potentials are used to preserve the backbone geometry (bond lengths, angles and improper/planar dihedral angles), while flexible dihedral angles are represented by cosine functions. Non-bonded atoms that are in contact in the PRE and POST structures are given 6–12 interactions with minima defined based on the endpoint configurations. These contacts were identified through use of the Shadow Contact Map algorithm64 with a cutoff distance of 6 Å, shadowing radius of 1 Å and residue sequence separations of 3 for proteins and 1 for RNA molecules. Atom pairs that are not identified as contacts are assigned an excluded volume interaction. The potential energy is given by
$$V = \mathop{\sum}\limits_{\,\text{bonds}\,}\frac{{\epsilon }_{{\rm{b}}}}{2}{(r-{r}_{{\rm{o}}})}^{2}+\mathop{\sum} \limits_{\,\text{angles}\,}\frac{{\epsilon }_{{{\theta }}}}{2}{(\theta -{\theta }_{{\rm{o}}})}^{2}+\ \mathop{\sum}\limits_{\,\text{impropers/planar}\,}\ \frac{{\epsilon }_{{\rm{\chi }}}}{2}{(\chi -{\chi }_{{\rm{o}}})}^{2}\\ \quad+\mathop{\sum} \limits_{\,\text{backbone-dihedrals}\,}{\epsilon }_{{\rm{bb}}}\ F(\phi )+\mathop{\sum}\limits_{\,\text{sidechain-dihedrals}\,}{\epsilon }_{{\rm{sc}}}\ F(\phi )\\ \quad+\mathop{\sum}\limits _{\,\text{non-contacts}\,}\ {\epsilon }_{{\rm{nc}}}{\left(\frac{{\sigma }_{{\rm{nc}}}}{{r}_{ij}}\right)}^{12}+\mathop{\sum}\limits_{\,\text{contacts}\,}{\epsilon }_{{{\rm{c}}}_{{\rm{k}}}}\ f({\sigma }_{ij,k},{r}_{ij})$$
(1)
where
$$F(\phi )=\left[1-\cos (\phi -{\phi }_{{\rm{o}}})\right]+\frac{1}{2}\left[1-\cos (3(\phi -{\phi }_{{\rm{o}}}))\right]$$
(2)
and the contacts function is given by
$$f(\sigma ,r)={\left(\frac{\sigma }{r}\right)}^{12}-2{\left(\frac{\sigma }{r}\right)}^{6}.$$
(3)
$$\left\{{r}_{{\rm{o}}}\right\}$$, $$\left\{{\theta }_{{\rm{o}}}\right\}$$, $$\left\{{\chi }_{{\rm{o}}}\right\}$$ and $$\left\{{\phi }_{{\rm{o}}}\right\}$$ were given the values found in the A/A–P/P configuration. ϵb = 100ϵ/Å2, ϵθ = 80ϵ/rad2, ϵχ = 40ϵ/rad2, ϵnc = 0.1ϵ, and σnc = 2.5 Å, and the dihedral-contact ratio was normalized, consistent with previous implementations of this model43. As noted above, contacts were defined based on two atomic structures: the A/A–P/P (PRE) and P/P–E/E (POST), each with native distances $$\left\{{\sigma }_{ij,{\rm{PRE}}}\right\}$$ and $$\left\{{\sigma }_{ij,{\rm{POST}}}\right\}$$. In our model, we rescaled $$\left\{{\sigma }_{ij,{\mathrm{{PRE}}}}\right\}$$ by 0.96 to prevent artificial inflation due to entropic effects. According to the default calculation of contact strength43, the strength of each contact was ϵc = 0.4951ϵ. However, since this model describes effective energetics, it was necessary to rescale the strength of tRNA–ribosome contacts (which form transiently), relative to the intra-ribosome contacts (which ensure structural stability of the assembly). After a parameter sweep, tRNA–50S contacts that are unique to the A/A–P/P configuration were given a weight of 0.15ϵc, tRNA–50S contacts that are unique to the P/P–E/E configuration were given a weight of 0.275ϵc. To ensure that the 3′-CCA end can stably bind the E site of the large subunit, contacts between A76 of the tRNA and residues G2421/A2422 were given a stronger weight of 1.5ϵc.
### Simulation details
All force field files were generated using the SMOG 2 software package (smog-server.org)43. Molecular dynamics simulations were performed using Gromacs (v5.1.4)65,66. Simulations were performed at a reduced temperature of 0.5$$\frac{\epsilon }{{k}_{B}}$$, where the temperature was maintained through use of Langevin dynamics protocols. Reduced units were used for all calculations. To study P/E formation, 10 independent simulations were performed for a minimum of 7 × 108 time steps (size 0.002), each. In order to probe the dynamics of tRNA when the ribosomal subunits are rotated, every ribosomal RNA atom (except for those in the L1 stalk) was harmonically restrained to a rotated conformation (TI$${\,}^{{\rm{Pre}}}$$ model, based on the cryo-EM study of ref. 10) with a spring constant of k = 0.1ϵ2. We also performed one additional simulation without position restraints, in order to verify that the P-site tRNA remains in a P/P configuration when the ribosome is unrotated. While the reported rates are based on free-energy barriers, when using this model and simulation protocols to study tRNA motion inside of the ribosome, one may alternately estimate that one reduced unit corresponds to ~1 ns67. This factor is used to obtain the effective simulated timescales in Fig. 2a Supplementary Fig. 5.
### Definitions of reaction coordinates
To describe the dynamics of P/E formation, we employed the following structural metrics:
• RP—distance between the geometric centers of the C75 functional group (non-backbone) in the P-site tRNA and the functional group of G2251 (Supplementary Fig. 2).
• RE—distance between the geometric centers of the C76 functional group in the P-site tRNA and the functional groups of G2421 and A2422 (Supplementary Fig. 3).
• RFRET—distance between the geometric centers of U47 in the A-site tRNA and U8 in the P-site tRNA (Supplementary Fig. 4).
• ρ1,2—linear combination two interatomic distances: 0.4r3 + 0.6r75, where ri is the distance between O3′ atoms of residue i in the P-site tRNA and C67 in the A-site tRNA (Fig. 4b). ρ1,2 was identified after an extensive analysis of possible collective coordinates (see below).
### Reaction coordinate analysis
In the diffusive regime, upon reaching the top of a free-energy barrier, the system will be equally likely to proceed to either the "reactant” or "product” state. That is, there is a probability of 0.5 that the system will successfully cross the underlying barrier. This may be expressed in terms of the conditional probability P(TPx): the probability that the system is undergoing a barrier-crossing event (i.e. on a Transition Path), given a configuration x. If x is within the TSE, then P(TPx) = 0.5. Similarly, if the coordinate ρ unambiguously identifies TSE configurations, then P(TPρ) will also yield a value of 0.5 at the TSE56,57. Here, for the I1–I2 transition, we calculated P(TPρ) for thousands of possible coordinates that are based on linear combinations of interatomic distances between the tRNA molecules. We find that a linear combination of two interatomic distances can minimize the number of apparent transitions (i.e. no false positives), while also yielding a value of P(TPρ) ~ 0.5 (Supplementary Fig. 19). The highest-performing coordinate was ρ1,2 (defined above).
### Calculating microscopic rates
To calculate the microscopic rates between dominant free-energy minima, we first defined the ensemble/states in terms of RP and RE. The I1, I2, P/E, and NE ensembles were defined as being centered at (RPRE) = (18.5, 42.5), (37.5, 18.5), (37.5, 3.5), (57.5, 28). Values are given in units of Å. The system was defined as being in a state if $$\sqrt{\Delta {R}_{\mathrm{{{P}}}}^{2}+\Delta {R}_{\mathrm{{{E}}}}^{2}}\, < \, 3\AA$$, where ΔRP/E is the difference between the instantaneous value of RP/E and the center of the defined state (Supplementary Fig. 12). Once the system reached a state, the system was considered to be in that state, until the boundary of a different state was crossed. The microscopic rate between ensemble i and j was then defined as kij = Nij/τi, where Nij is the number of observed transitions from state i to state j and τi is the total simulated time for which the system was in ensemble i. Here, we only calculated the rate if Nij > 20. In addition, while rates to/from P/P′ were not considered, for the analysis of kinetics, the system was defined as "not-I1” when a P/P′ configuration was sampled, until the system readopted an I1 configuration. P/P’ configurations were defined as being centered about (RPRE) = (6, 48). Calculated rates are given in Supplementary Table 1.
### Free-energy perturbation calculations
Free-energy perturbation calculations were performed to study the effects of steric-gate modifications (Fig. 5), different A-site tRNA positions (Fig. 6), and electrostatic interactions (Supplementary Fig. 14). In these cases, the change in free energy was calculated according to the relation68:
$$\Delta F=-{{k}}_{{\rm{B}}}T{\mathrm{ln}}\,{\left\langle \exp \left(-\frac{\Delta U}{{{k}}_{{\rm{B}}}T}\right)\right\rangle }_{0,{\rho }_{1,2}}.$$
(4)
ΔU is the change in potential energy upon introducing a modification to the model. $${\langle ...\rangle }_{0,{\rho }_{1,2}}$$ denotes an ensemble average taken over the simulated frames for which the ribosome adopts a given value of ρ1,2.
#### Steric-gate perturbations
For the steric-gate calculations (Fig. 5d), ΔU was defined as the change in potential energy associated with excluded-volume interactions between tRNA and the gate residues (Fig. 5c).
#### A-site tRNA position perturbations
To assess the influence of the A-site tRNA position on the free energy of the P-site tRNA (Fig. 6c), ΔU was defined by a hard-sphere potential between the atoms in the A/P or A/P* structures and the simulated P-site tRNA: ΔU = ∞ if the minimal intermolecular distance is <2.5 Å.
#### Electrostatic effects
To obtain an initial insight into the influence of electrostatic interactions, we assigned partial charges to each atom and then applied a screened-electrostatic (Debye–Hückel) potential between the P-site tRNA and the 50S subunit. Charges were based on the amber99sb-ildn forcefield69. Since the structure-based model does not explicitly represent hydrogen atoms, the charge on each hydrogen atom in the AMBER forcefield was added to the corresponding heavy atom in the SMOG model. The parameters for the Debye–Hückel potential were taken from ref. 70, with a monovalent ion concentration of 100 mM and a uniform dielectric constant of 80. The potential was truncated at 20 Å.
### Reporting summary
Further information on research design is available in the Nature Research Reporting Summary linked to this article.
## Data availability
All the data are available upon reasonable request.
## References
1. 1.
Schmeing, T. M. & Ramakrishnan, V. What recent ribosome structures have revealed about the mechanism of translation. Nature 461, 1234–1242 (2009).
2. 2.
Korostelev, A. & Noller, H. F. The ribosome in focus: new structures bring new insights. Trends Biochem. Sci. 32, 434–441 (2007).
3. 3.
Frank, J., Gao, H., Sengupta, J., Gao, N. & Taylor, D. J. The process of mRNA-tRNA translocation. Proc. Natl Acad. Sci. USA 104, 19671–19678 (2007).
4. 4.
Rodnina, M. V. & Wintermeyer, W. Fidelity of aminoacyl-tRNA selection on the ribosome: kinetic and structural mechanisms. Annu. Rev. Biochem. 70, 415–435 (2001).
5. 5.
Frank, J. & Agrawal, R. A ratchet-like inter-subunit reorganization of the ribosome during translocation. Nature 406, 318–322 (2000).
6. 6.
Valle, M. et al. Locking and unlocking of ribosomal motions. Cell 114, 123–134 (2003).
7. 7.
Moazed, D. & Noller, H. F. Intermediate states in the movement of transfer RNA in the ribosome. Nature 342, 142 (1989).
8. 8.
Horan, L. H. & Noller, H. F. Intersubunit movement is required for ribosomal translocation. Proc. Natl Acad. Sci. USA 104, 4881–4885 (2007).
9. 9.
Brilot, A. F., Korostelev, A. A., Ermolenko, D. N. & Grigorieff, N. Structure of the ribosome with elongation factor G trapped in the pretranslocation state. Proc. Natl Acad. Sci. USA 110, 20994–20999 (2013).
10. 10.
Ratje, A. et al. Head swivel on the ribosome facilitates translocation by means of intra-subunit tRNA hybrid sites. Nature 468, 713–716 (2010).
11. 11.
Dunkle, J. A. et al. Structures of the bacterial ribosome in classical and hybrid states of tRNA binding. Science 332, 981–984 (2011).
12. 12.
Nguyen, K. & Whitford, P. C. Steric interactions lead to collective tilting motion in the ribosome during mRNA–tRNA translocation. Nat. Commun. 7, 10586–10586 (2016).
13. 13.
Ogle, J. M., Carter, A. P. & Ramakrishnan, V. Insights into the decoding mechanism from recent ribosome structures. Trends Biochem. Sci. 28, 259–266 (2003).
14. 14.
Agirrezabala, X. et al. Visualization of the hybrid state of tRNA binding promoted by spontaneous ratcheting of the ribosome. Mol. Cell 32, 190–197 (2008).
15. 15.
Fischer, N., Konevega, A. L., Wintermeyer, W., Rodnina, M. V. & Stark, H. Ribosome dynamics and tRNA movement by time-resolved electron cryomicroscopy. Nature 466, 329–333 (2010).
16. 16.
Frank, J. Intermediate states during mRNA–tRNA translocation. Curr. Opin. Struct. Biol. 22, 778–785 (2012).
17. 17.
Korostelev, A., Trakhanov, S., Laurberg, M. & Noller, H. F. Crystal structure of a 70S ribosome-tRNA complex reveals functional interactions and rearrangements. Cell 126, 1065–1077 (2006).
18. 18.
Jenner, L., Rees, B., Yusupov, M. & Yusupova, G. Messenger RNA conformations in the ribosomal E site revealed by X-ray crystallography. EMBO Rep. 8, 846–850 (2007).
19. 19.
Blanchard, S. C., Kim, H. D., Gonzalez, R. L., Puglisi, J. D. & Chu, S. tRNA dynamics on the ribosome during translation. Proc. Natl Acad. Sci. USA 101, 12893–12898 (2004).
20. 20.
Munro, J. B. et al. Spontaneous formation of the unlocked state of the ribosome is a multistep process. Proc. Natl Acad. Sci. USA 107, 709–714 (2010).
21. 21.
Fei, J. et al. Allosteric collaboration between elongation factor G and the ribosomal L1 stalk directs tRNA movements during translation. Proc. Natl Acad. Sci. USA 106, 15702–15707 (2009).
22. 22.
Cornish, P. V., Ermolenko, D. N., Noller, H. F. & Ha, T. Spontaneous intersubunit rotation in single ribosomes. Mol. Cell 30, 578–588 (2008).
23. 23.
Ermolenko, D. N. et al. Observation of intersubunit movement of the ribosome in solution using FRET. J. Mol. Biol. 370, 530–540 (2007).
24. 24.
Rodnina, M. V., Savelsbergh, A. & Wintermeyer, W. Dynamics of translation on the ribosome: molecular mechanics of translocation. FEMS Microbiol. Rev. 23, 317–333 (1999).
25. 25.
Rodnina, M. V. & Wintermeyer, W. The ribosome as a molecular machine: the mechanism of tRNA–mRNA movement in translocation. Biochem. Soc. Trans. 39, 658–662 (2011).
26. 26.
Pan, D., Kirillov, S. V. & Cooperman, B. S. Kinetically competent intermediates in the translocation step of protein synthesis. Mol. Cell 25, 519–529 (2007).
27. 27.
Munro, J. B., Altman, R. B., O’Connor, N. & Blanchard, S. C. Identification of two distinct hybrid state intermediates on the ribosome. Mol. Cell 25, 505–517 (2007).
28. 28.
Zhou, J., Lancaster, L., Donohue, J. P. & Noller, H. F. How the ribosome hands the A-site tRNA to the P site during EF-G–catalyzed translocation. Science 345, 1188–1191 (2014).
29. 29.
Bryngelson, J. D. & Wolynes, P. G. Intermediates and barrier crossing in a random energy-model (with applications to protein folding). J. Phys. Chem.-US 93, 6902–6915 (1989).
30. 30.
Bryngelson, J. D., Onuchic, J. N., Socci, N. D. & Wolynes, P. G. Funnels, pathways, and the energy landscape of protein-folding—a synthesis. Proteins 21, 167–195 (1995).
31. 31.
Onuchic, J., Luthey-Schulten, Z. & Wolynes, P. Theory of protein folding: the energy landscape perspective. Annu. Rev. Phys. Chem. 48, 545–600 (1997).
32. 32.
Kubelka, J., Hofrichter, J. & Eaton, W. A. The protein folding ‘speed limit’. Curr. Opin. Struct. Biol. 14, 76–88 (2004).
33. 33.
Thirumalai, D. & Hyeon, C. RNA and protein folding: common themes and variations. Biochemistry 44, 4957–70 (2005).
34. 34.
Kim, H. et al. Protein-guided RNA dynamics during early ribosome assembly. Nature 506, 334–338 (2014).
35. 35.
Pierro, M. D., Potoyan, D. A., Wolynes, P. G. & Onuchic, J. N. Anomalous diffusion, spatial coherence, and viscoelasticity from the energy landscape of human chromosomes. Proc. Natl Acad. Sci. USA 115, 7753–7758 (2018).
36. 36.
Zhuravlev, P. I. & Papoian, G. A. Molecular noise of capping protein binding induces macroscopic instability in filopodial dynamics. Proc. Natl Acad. Sci. USA 106, 11570–11575 (2009).
37. 37.
Dashti, A. et al. Trajectories of the ribosome as a Brownian nanomachine. Proc. Natl Acad. Sci. USA 111, 17492–17497 (2014).
38. 38.
Levi, M., Noel, J. K. & Whitford, P. C. Studying ribosome dynamics with simplified models. Methods 162–163, 128–140 (2019).
39. 39.
Bock, L. V., Blau, C., Vaiana, A. C. & Grubmüller, H. Dynamic contact network between ribosomal subunits enables rapid large-scale rotation during spontaneous translocation. Nucleic Acid Res. 43, 6747–6760 (2015).
40. 40.
Adamczyk, A. J. & Warshel, A. Converting structural information into an allosteric-energy-based picture for elongation factor tu activation by the ribosome. Proc. Natl. Acad. Sci. USA 108, 9827–9832 (2011).
41. 41.
Trobro, S. & Aqvist, J. Role of ribosomal protein L27 in peptidyl transfer. Biochemistry 47, 4898–906 (2008).
42. 42.
Whitford, P. C. et al. An all-atom structure-based potential for proteins: bridging minimal models with all-atom empirical forcefields. Prot. Struct. Funct. Bioinform. 75, 430–441 (2009).
43. 43.
Noel, J. K. et al. SMOG 2: A versatile software package for generating structure-based models. PLoS Comput. Biol. 12, e1004794 (2016).
44. 44.
Bock, L. V. et al. Energy barriers and driving forces in tRNA translocation through the ribosome. Nat. Struct. Mol. Biol. 20, 1390–1396 (2013).
45. 45.
Whitford, P. C. & Sanbonmatsu, K. Y. Simulating movement of tRNA through the ribosome during hybrid-state formation. J. Chem. Phys. 139, 121919 (2013).
46. 46.
Hyeon, C. & Thirumalai, D. Capturing the essence of folding and functions of biomolecules using coarse-grained models. Nat. Commun. 2, 487 (2011).
47. 47.
Chan, H. S., Zhang, Z., Wallin, S. & Liu, Z. Cooperativity, local–nonlocal coupling, and nonnative interactions: principles of protein folding from coarse-grained models. Annu. Rev. Phys. Chem. 62, 301–326 (2011).
48. 48.
Okazaki, K. & Takada, S. Dynamic energy landscape view of coupled binding and protein conformational change: induced-fit versus population-shift mechanisms. Proc. Natl Acad. Sci. USA 105, 11182–11187 (2008).
49. 49.
Nguyen, K., Yang, H. & Whitford, P. C. How the ribosomal A-site finger can lead to tRNA species-dependent dynamics. J. Phys. Chem. B 121, 2767–2775 (2017).
50. 50.
Fei, J., Kosuri, P., Macdougall, D. & Gonzalezjr, R. Coupling of ribosomal L1 stalk and tRNA dynamics during translation elongation. Mol. Cell 30, 348–359 (2008).
51. 51.
Kim, H. D., Puglisi, J. D. & Chu, S. Fluctuations of transfer RNAs between classical and hybrid states. Biophys. J. 93, 3575–3582 (2007).
52. 52.
Graf, M. et al. Visualization of translation termination intermediates trapped by the Apidaecin 137 peptide during RF3-mediated recycling of RF1. Nat. Commun. 9, 1–11 (2018).
53. 53.
Svidritskiy, E., Demo, G., Loveland, A. B., Xu, C. & Korostelev, A. A. Extensive ribosome and RF2 rearrangements during translation termination. eLife 8, 1–18 (2019).
54. 54.
Noel, J. K., Chahine, J., Leite, V. B. P. & Whitford, P. C. Capturing transition paths and transition states for conformational rearrangements in the ribosome. Biophys. J. 107, 2872–2881 (2014).
55. 55.
Levi, M. & Whitford, P. C. Dissecting the energetics of subunit rotation in the ribosome. J. Phys. Chem. B 123, 2812–2923 (2019).
56. 56.
Best, R. B. & Hummer, G. Reaction coordinates and rates from transition paths. Proc. Natl Acad. Sci. USA 102, 6732–6737 (2005).
57. 57.
Hummer, G. From transition paths to transition states and rate coefficients. J. Chem. Phys. 120, 516–523 (2004).
58. 58.
Whitford, P. C., Blanchard, S. C., Cate, J. H. D. & Sanbonmatsu, K. Y. Connecting the kinetics and energy landscape of tRNA translocation on the ribosome. PLoS Comput. Biol. 9, e1003003 (2013).
59. 59.
Noel, J. K. & Whitford, P. C. How EF-Tu can contribute to efficient proofreading of aa-tRNA by the ribosome. Nat. Commun. 7, 13314 (2016).
60. 60.
Yang, H., Noel, J. K. & Whitford, P. C. Anisotropic fluctuations in the ribosome determine tRNA kinetics. J. Phys. Chem. B 121, 2777–2786 (2017).
61. 61.
Dhar, A. et al. Structure, function, and folding of phosphoglycerate kinase are strongly perturbed by macromolecular crowding. Proc. Natl Acad. Sci. USA 107, 17586–17591 (2010).
62. 62.
Bernier, C. R., Petrov, A. S., Kovacs, N. A., Penev, P. I. & Williams, L. D. Translation: the universal structural core of life. Mol. Biol. Evol. 35, 2065–2076 (2018).
63. 63.
Jenner, L. B., Demeshkina, N., Yusupova, G. & Yusupov, M. Structural aspects of messenger RNA reading frame maintenance by the ribosome. Nat. Struct. Mol. Biol. 17, 555–560 (2010).
64. 64.
Noel, J. K., Whitford, P. C. & Onuchic, J. N. The shadow map: a general contact definition for capturing the dynamics of biomolecular folding and function. J. Phys. Chem. B 116, 8692–8702 (2012).
65. 65.
Lindahl, E., Hess, B. & van der Spoel, D. Gromacs 3.0: a package for molecular simulation and trajectory analysis. J. Mol. Mod. 7, 306–317 (2001).
66. 66.
Hess, B., Kutzner, C., van der Spoel, D. & Lindahl, E. GROMACS 4: algorithms for highly efficient, load-balanced, and scalable molecular simulation. J. Chem. Theory Comput. 4, 435–447 (2008).
67. 67.
Yang, H. et al. Diffusion of tRNA inside the ribosome is position-dependent. J. Chem. Phys. 151, 085102 (2019).
68. 68.
Zwanzig, R. W. High-temperature equation of state by a perturbation method. I. nonpolar gases. J. Chem. Phys. 22, 1420–1426 (1954).
69. 69.
Lindorff-Larsen, K. et al. Improved side-chain torsion potentials for the Amber ff99SB protein force field. Prot. Struct. Funct. Bioinform. 78, 1950–1958 (2010).
70. 70.
Givaty, O. & Levy, Y. Protein sliding along DNA: dynamics and structural characterization. J. Mol. Biol. 385, 1087–1097 (2009).
## Acknowledgements
This work was supported by the NSF (Grants MCB-1915843 and MCB-1350312). Work at the Center for Theoretical Biological Physics is supported by the NSF (Grant PHY-2019745). We are grateful for support from the Office of Northeastern University Program In Multicultural Engineering (NUPRIME) within the College of Engineering. We would also like to acknowledge generous computational and technical support provided by the the Northeastern University Discovery Cluster and Research Computing department. The authors declare no competing financial interests.
## Author information
Authors
### Contributions
M.L. performed all simulations. All authors contributed to data analysis. M.L., A.W., U.M., and P.C.W prepared the manuscript. P.C.W. designed the study.
### Corresponding author
Correspondence to Paul C. Whitford.
## Ethics declarations
### Competing interests
The authors declare no competing interests.
Peer review information Nature Communications thanks Lars Bock, and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
## Rights and permissions
Reprints and Permissions
Levi, M., Walak, K., Wang, A. et al. A steric gate controls P/E hybrid-state formation of tRNA on the ribosome. Nat Commun 11, 5706 (2020). https://doi.org/10.1038/s41467-020-19450-0
• Accepted:
• Published:
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# Nick DeBrita is alive and well (sorta)...
### Help Support The Rocketry Forum:
#### jflis
##### Well-Known Member
I just received a letter from Nick DeBrita.
I get the impression he's had happier times
such is life in the military (remind me to relate the story about how my brother belted his sargent during the last week of boot camp... LOL)
here it is, straight from Nick, currently learning all he needs to know about how to protect our liberties:
========================
(I love how he begins this: "JIM, PLEASE POST THIS LETTER ON THE FORUM. PARDON THE ALL CAPITAL LETTERS. THATS THE ONLY WAY WE ARE ALLOWED TO WRITE.") man, and I thought my *mom* was strict... LOL
Now's it going? It really sucks here. The first week was the worst. The first night we didn't get any sleep at all. We were doing processing stuff all night and the next day. It sucked big time. During our first issue, we got sneakers. Mine weren't laced up so I started to lace them up. A guy came over and started screaming in my face for lacing them up. 20 minutes later, another guy starts screaming at me for NOT lacing them up. It wasnt cool at all.
My shipmates are pretty cool. There are a few idiots and there are a few jerks. Ive gotten into a few shouting matches already. It drives me nuts when people dont listen and they mess things up. I am not afraid to tell people how I feel.
The food here sucks. Breakfast is the same thing every day. Scrambled eggs, bacon, French toast. Every day. The whole eating experience sucks. No talking and not time. You have 10 minutes from when the last person sits down. Eat it now, taste it later.
When we are marching to class, we go past a standard missile w/ Terrier booster. The only problem is, we arent allowed to look around. We have to look straight ahead.
I am really missing the comforts of home right now. I havent heard music in two weeks. I havent been on the forum either!
My graduation day is April 2nd. That weekend, Ill get on the computer and say Hi.
Ill write a few more letters. Hopefully I will get a few from you guys.
See you later.
Sr. DeBrita, Nicholas
DIV135 Ship 10
Recruit Training Command
3301 Indiana St.
Great Lakes, IL 60088-3127
#### jflis
##### Well-Known Member
Ok folks!
Let's get that letter writting machine well oiled and make sure that Nick knows we're thinkin' of him!
jim
#### Mike
##### Well-Known Member
Chin up Nick! Here's hoping things get a little better for you.
#### BlueNinja
##### Well-Known Member
Yeesh... Hope it gets better for the remainder of the time... Oh well, April isn't that far away.
(Don't tell Nick this, but that makes a 48 minute art class look short!)
Start the storytellin.
##### Well-Known Member
Sure...you think it sucks now. At some point down the road it will make sense. In the mean time, be happy they aren't shoving chipped beef on toast down your gulet!
#### powderburner
##### Well-Known Member
Believe it or not, you will actually look fondly on these memories at some point in the future.
You will have some newbie join your unit, and he will describe how horrible his time was in basic, and you will lean back (like the experienced old hand that you will be) and tell him all about, "Why, when I went through basic back in ought-4, we REALLY had it tough!"
One school of thought has it that the instructors are trying to erase all individual identity, to help you change your thinking and behavior to be part of a unit.
Another school of thought is that they are just a bunch of sadistic a**holes.
You choose.
#### wwattles
##### Well-Known Member
I heard that same thought expressed this way, and it doesn't just apply to the military:
"An organization is a lot like a tree full of monkeys.
Some are climbing up, others are climbing down.
The ones on the top look down and see a bunch of smiling faces.
The ones on the bottom look up and see a bunch of a**holes."
I'll share that w/ Nick when he gets back online...
WW
#### eugenefl
##### Well-Known Member
TRF Supporter
Awe man...I actually *miss* boot camp breakfast! Now *that* was the best part of my day. I specifically enjoyed devouring an orange in less than a minute. (Cut into four quarters, insert orange into mouth like a mouthguard, and chomp out the pulp in one bite. Repeat for remaining quarters.)
Now, for those of you that *really* want to give Nick a hard time, be sure and visit your local drugstore and pick up the tacky postcard with the woman baring buns via T-backs! His drill seargants will *LOVE* that! Wanna know how I know? My uncle sent me one! :kill:
#### Rocketmaniac
##### Well-Known Member
Oh the life in basic!!!!! You just got to love it...... That was 19 years ago, and I still remember the first night......... Yes, they tear you down to nothing, and then build you back up (the way they want you to be)......
#### jflis
##### Well-Known Member
yea..
Join the military...
...Be all they want you to be!
#### wwattles
##### Well-Known Member
I think Nick needs a picture postcard from someone with a monstrous rocket on liftoff with the caption "Accelerate your life? Accelerate THIS!"
WW
#### Chilly
##### Well-Known Member
My favorite memory from Parris Island:
"What the [email protected] you lookin at recruit? You wanna buy the [email protected]$% place?" "Sir yes sir! Would the Drill Instructor have change for a quarter, sir?" #### DavRedf ##### Well-Known Member Hey Nick Thats because the neaderthals, sorry DI's, can't read very well and need you to write in capitals so the can try and figue out if you are writing home about them. Keep going Nick in later life you really will laugh about boot camp. All the best David #### PGerringer ##### Ruler of Heck Originally posted by Chilly My favorite memory from Parris Island: "What the [email protected] you lookin at recruit? You wanna buy the [email protected]$% place?"
"Sir yes sir! Would the Drill Instructor have change for a quarter, sir?"
OMG!!! I just spit my cereal all over my laptop. LOL!!!!
Jim, are there any special rules for sending him mail? I want to send him some encouraging words. Ah, who the heck am I kidding, I want to send him the naked lady postcard Eugene was talking about. Seriously, can I send him a fruitcake with a file in it? Oh, thats prison. Does he get an extra stripe for having the most mail sent to him?
#### jflis
##### Well-Known Member
i'm not aware of any *special rules*, though I would suspect there is a chance that his mail could be *reviewed* ahead of time...
i'll be sending him a note this week. I would encourage everyone who knows him (even if just through TRF) drop him a quick note, even if it's just a post card
#### Stymye
##### Well-Known Member
during my stay .we had to open our mail in front of the drill sgt
If anything illicit fell out .... you were given one chance to dispose of it right away (and yes it happened more than a few times),
If you got any type of food you had to share it with your buddies......
#### Chilly
##### Well-Known Member
OK, I was a Gyrene so I don't know how Navy boot is...but DO NOT send that poor guy food! Unless you don't like him, that is .
Mail that's guaranteed to get him in trouble:
1. Porno
2. Male Porno (not as funny as you probably think it is when you slip that copy of "Playgirl" into the mail box)
3. Food
4. Civilian clothes - including funny t-shirts
5. Anything that says "Long live Osama"
6. AP reloads probably NOT a good idea either...
#### Silverleaf
##### Well-Known Member
Air Force - basic training May 83...
We each had a number..mine was 3, that way when they called the number, we'd run and get in line and be in alphabeltical order for whatever hell they had for us that day...So heres how it sounded as they reached 24:
24.. Moore Sir
25 ..Moore Sir
26 ..Moore Sir
27.. Moore Sir
28 ..Moore Sir
29 ..Moore Sir
30 ..Muchmoore Sir
We had 2 Howard Johnson's in our flight, and my best friend, a Jamaican whom had lived in England, had a funky English - Jamiacan accent, and his name ?..Robin Williams.
We had 1 guy get bit by a Brown Recluse, head swelled up like a basketball, and we were known as the Honor flight, no darn TI stayed round long enough to get to know us, so needless to say, we had very few 351's pulled.
The day I graduated, my TI - Sgt. Slayton - a 19 year vet whom I still respect to this day, pulled my hat off, asked for a 351 and when he signed it he handed it back..saying, take this for your posterior " On it, it said Excellence in Basic Training "..when I said Sir ?
He said, " Yeah Shove it up your A**"
Ah, the military life, can't say I miss it - except for being based at Beale AFB. CA and seeing SR-71's take off everyday. My best memory was a flight on a dual seater, all because while in basic, we were pulled in our last day by the First Sgt and given a break..sort of.
He asked all sorts of questions about a certain plane - the SR-71 and I was the only one that knew all the answers. He asked me how I knew all the answers, and I told him " Sir, Airman Barker reports, I build models as a Hobby, and have the book on the SR-71 that has specs and the like".
At the end, I was called to the back, and met two pilots, a Captain and Major.. So when I was stationed at Beale 15 weeks later, I was told to report to the flight line...and there she sat.
The Major walked up to me, I saluted and he said, go get in a flight suit, you get to sit in one of these. I did, and only thought I was going to sit in it, when he said..wheres your helmet ?
I said..umm, OHH !!..took off like a rocket, 1/2 way turned to salute him as I left his presence, fell flat on my face, and was badk in a flash.
I remember taking off, and literally being blasted into the seat, the air forced out of my lungs. Amazing...
Then he had me place my gloved hand against the window, I didn't feel anything and he said, never touch the window without the gloves on..its 600 degrees. We refueled shortly thereafter, and made a trip up and around Canada, and back down over the Rockies, all at 50,000 feet or so.
Thankfully I hadn't eaten anything..because i would have lost it.
#### jetra2
##### Well-Known Member
WOW!!!
You actually got to ride in an SR-71 ...you lucky SOB!
Congrats on experiencing that once in a lifetime event...now I'm jealous! :kill:
Jason
#### Chilly
##### Well-Known Member
Was that in a full pressure suit or regular zoom-bag?
#### jetra2
##### Well-Known Member
I just copied the address down onto a postcard - it's going out this morning! I'm suere he'll be glad to hear from us!
Jason
#### jflis
##### Well-Known Member
Jason,
Nick was *thrilled* to get your post card
I just got this from Nick:
==================
Hey guys,
This place has gotten a lot better. Im getting in much better shape too. In high school I couldnt run the mile without having to stop and walk. On Friday, I ran 2 miles in 18 minutes. Afterwards, I said something I never thought Id say after a two mile run. That was easy.
Right now, the only really bad part about boot camp is the fact that everyone is sick. I was SIQ (Sick In Quarters) for a day. I had a temperature of 102.5. I was only allowed out of my rack to use the head and to eat. It was cool at first, but then it got boring. I also have swimmers ear right now. I took my swim test on Tuesday. I cant hear much out of my right ear. The swim test was kind of fun. It started off with a jump off a 10 foot platform, a 50 yard swim, and a 5 minute prone float. The prone float was tough. You could come up for air as often as you want, but I couldnt catch my breath when I came up. They kept yelling at me for that.
We are almost done. Battle Stations is on March 25th. Battle Stations is the final test. It lasts all night. You do all this crazy stuff like navigate an obstacle course in the dark while carrying a stretcher loaded with the heaviest recruit. You do all sorts of stuff. At the end, you have the Ball Cap Ceremony. During boot camp, you have a ball cap that says RECRUIT on it. After Battle Stations, you get the Navy Ball Cap. After that, you are no longer considered a recruit. You are called a Sailor. A week after Battle Stations, I have graduation. Graduation is on April 2nd. I cant wait. My parents are coming out to see it. After graduation, I have 3 days liberty. At this Navy exchange they have internet computers so I will be able to chat with you guys for a little while. After boot camp, Im buying a laptop so in a few weeks, you guys can get me up to date on everything.
Jason Toft, thanks for the postcard. Every piece of mail I get is great. Its like a little piece of home. Phone calls are better. Our ROCs like to give us phone calls when we do good on tests and inspections. It feels great to be able to call home and talk to my family.
Well, Ill talk to all of you for a little while in about 3 weeks. A few weeks after that, Ill be back to the forum on a regular basis.
Talk to you then.
Nick Rocketman248
Sr Debrita, Nicholas J.
Div 135 Ship 10
Recruit Training Command
3301 Indiana Street
Great Lakes, IL 60088
#### eugenefl
##### Well-Known Member
TRF Supporter
I just typed him up a letter and printed out the pictures of the Sidewinder flying off the aircraft carrier deck. I'll be dropping it off in the mail on my way to lunch. He should get a kick out of that.
Mail call in boot camp was absolutely one of my three favorite times. You really get to connect with the outside world for a few moments. If you have the time, definitely drop Nick a line. Even if it's a postcard like what Jason sent, he'll appreciate it.
Aside from being sick, which happens to everyone in boot camp, I'm glad to hear he's doing well. Some guys get recycled in training and end up having to stay an extra 2 weeks!
Later all!
#### Rocketman248
##### Well-Known Member
Well, I did it. I'm a Sailor. We had Battle Stations thursday night. It was a ton of fun. It started at 8:00PM Thursday night. We got our Navy ballcap at 9:30AM Friday morning. It feels great every time I look at that cap.
Right now, I am at "Ricky Heaven." There is a phone center, internet computers, and a few fast food retaurnts. I have aa few hours so, I jusut thought I'd drop a line.
I really apreciate the letters I've gotten from you guys. In a few weeks, I'll be on here all the time. I have graduation, on April 2nd. April 4th I go to my first school. I will buy a laptop when i get there.
See you in a few weeks.
#### jflis
##### Well-Known Member
Congratulations to a new Sailor!
That's great news Nick!
keep us posted and let us know how yer doing!
#### mikeyd
##### Old Rocketeer
As Jim said CONGRATULATIONS SAILOR , and God bless you, and all the Men and Women, helping to keep us safe at free!!!
#### wwattles
##### Well-Known Member
Nick,
Welcome to the Fleet! I'm sure you'll enjoy it as much as I have!
WW
#### Ryan S.
##### Well-Known Member
congratss!!!!!!! its great to hear from you!!
#### BlueNinja
##### Well-Known Member
Congrats man! Keep us posted!
#### eugenefl
##### Well-Known Member
TRF Supporter
All rocketeers, "ATTENTION ON DECK!" Congratulations Nick! That's awesome that you are through bootcamp. I tell ya, time flies. The next thing you know they'll be offering you re-enlistment paperwork. Good luck with tech training and keep in touch!
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# P2886 [USACO07NOV]牛继电器Cow Relays
• 479通过
• 989提交
• 题目提供者 FarmerJohn2
• 评测方式 云端评测
• 标签 动态规划,动规,dp 最短路 矩阵乘法 USACO 2007 高性能
• 难度 提高+/省选-
• 时空限制 1000ms / 128MB
• 提示：收藏到任务计划后，可在首页查看。
## 题目描述
For their physical fitness program, N (2 ≤ N ≤ 1,000,000) cows have decided to run a relay race using the T (2 ≤ T ≤ 100) cow trails throughout the pasture.
Each trail connects two different intersections (1 ≤ I1i ≤ 1,000; 1 ≤ I2i ≤ 1,000), each of which is the termination for at least two trails. The cows know the lengthi of each trail (1 ≤ lengthi ≤ 1,000), the two intersections the trail connects, and they know that no two intersections are directly connected by two different trails. The trails form a structure known mathematically as a graph.
To run the relay, the N cows position themselves at various intersections (some intersections might have more than one cow). They must position themselves properly so that they can hand off the baton cow-by-cow and end up at the proper finishing place.
Write a program to help position the cows. Find the shortest path that connects the starting intersection (S) and the ending intersection (E) and traverses exactly N cow trails.
给出一张无向连通图，求S到E经过k条边的最短路。
## 输入输出格式
输入格式：
* Line 1: Four space-separated integers: N, T, S, and E
* Lines 2..T+1: Line i+1 describes trail i with three space-separated integers: lengthi , I1i , and I2i
输出格式：
* Line 1: A single integer that is the shortest distance from intersection S to intersection E that traverses exactly N cow trails.
## 输入输出样例
输入样例#1： 复制
2 6 6 4
11 4 6
4 4 8
8 4 9
6 6 8
2 6 9
3 8 9
输出样例#1： 复制
10
提示
标程仅供做题后或实在无思路时参考。
请自觉、自律地使用该功能并请对自己的学习负责。
如果发现恶意抄袭标程，将按照I类违反进行处理。
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# What to look for in a motor?
I am going to be making a small robot using a Arduino Mega ADK Rev3 with 4 motors, and about a pound of other stuff. This is the first time I'm doing any major hardware project, so I'm not really sure what to look for in a motor.
• What are the motors being used for? – helloworld922 Sep 8 '12 at 3:31
• A small robot, doesn't carry any load besides itself, just to cruise around. When I say small, I mean about the size of a sheet of paper, but much taller ofcourse :p – Oztaco Sep 8 '12 at 3:58
• So they're used to drive the wheels? Treads? – helloworld922 Sep 8 '12 at 5:09
• Drive the wheels – Oztaco Sep 8 '12 at 17:37
## 2 Answers
There are a few primary specifications you should look for in a motor:
1. The type of the motor. There are a variety of different electric motors out there. In my experience the cheapest ones are brushed DC motors. These are fairly simple to drive: you send the motor a PWM signal and it spins faster with a higher duty cycle. Reverse the polarity and they spin the other way. I'm guessing this will probably fit your project the best.
2. Electrical characteristics. This includes the nominal voltage the motor runs at, what the stall current is, and what the rated current is (note: the rated current doesn't necessarily have to be greater than the stall current). Most DC motors I've used which are capable of driving semi-small to medium sized robots (about what size you have, though probably heavier) run in the 12-24V range so you may have to plan your battery packs accordingly. The stall currents has varied anywhere from a 1-2 amps to over 30 amps.
3. Mechanical characteristics. This includes the no-load speed of the motor, the stall torque of the motor, and any other mechanical characteristics such a rated torque or any gear ratio present (if in a geared motor). DC motors have a linear torque to speed ratio, i.e. they develop the maximum torque when stalled which decreases until the motor is spinning at it's maximum speed. The speed-power curve increases until the motor reaches half the no-load speed and then decreases. Typical DC motors have a very high no-load speed. Most I've seen vary between ~5000 rpm up to ~20000 rpm, though much high rpm ranges are definitely available.
Here's how I would determine what kind of motor to look for:
First I would figure out what kind of speed I want my robot to achieve. Next I would determine roughly how much my robot weighs. I would do a quick survey of what motors are available keeping in mind the mechanical characteristics. A quick calculation of the max speed of a robot is:
$$speed_{robot} = diameter_{wheels} * \pi * speed_{motor} / gear~ratio$$
The required torque is a trickier quantity to calculate as you'd need to know what kind of friction/resistance your robot is going to encounter and know roughly how much your robot weighs. Assuming rotational inertia of the wheels is small compared to the mass of the robot (and if I did my math right), the ideal speed of the robot vs. time is given by:
$$V(t) = w_d \cdot \pi \cdot \omega_{NL} \cdot ( 1 - e ^ {\large{- \tau_S / (2 \pi \cdot m \cdot \omega_{NL}) t}})$$
Where:
$$V(t) = robot~speed$$ $$w_d = wheel~diameter$$ $$\omega_{NL} = no-load~motor~speed~(including~gear~ratio)$$ $$\tau_S = stall~torque~(including~gear~ratio)$$ $$m = mass~of~robot$$ $$t = time$$ $$\pi = 3.14...$$ $$e = 2.72...$$
You can add the torque of all the drive motors together.
I would then design the electrical systems to fit the required electrical characteristics of the motor. This includes the motor driver, battery packs, and any wiring.
Gear ratio is the ratio between the input speed divided by the output speed of a gear box. They are used to speed up or more often slow down the output drive shaft speed. As a consequence of the speed ratio change the output torque also changes. In an ideal gear box with 100% efficiency the gear ratio is equal to the output torque divided by the input torque. This is mostly true for real gear boxes, but in reality most gear boxes lose ~2% between gear mesh (note that this relation is exponential as each gear mesh produces an input/output set, so for a gear box with 12 meshes the efficiency drops from 100% to ~78.5%).
• Say, you're not a physicist, are you? To an EE e = 2.72, and pi = 3.14 (sometimes just 3). How accurate do you want to express speed, and how many of your significant digits will be correct? – stevenvh Sep 8 '12 at 15:57
• :P I'm actually a mech-e, so I've used pi=e=3 many times. Or more often, I just type "pi" or "e" and the computer computes it to machine precision and I chop all but a few sig figs. – helloworld922 Sep 8 '12 at 15:58
• Thanks for the answer, could you explain gear ratio though? – Oztaco Sep 9 '12 at 4:27
• added a section about gear ratios. – helloworld922 Sep 10 '12 at 3:19
This is a very complicated issue. It entails a lot of questions. For instance: what kind of motor are you going to use? Are you going to use a gearbox? How heavy is the battery? How heavy and strong is your robot enclosure?
Motors are characterized by their speed/torque curve. You'll find that most electric motors are not capable of achieving high torque for small speeds, like the speed you'd expect from a mobile robot wheel. What that essentially means is that you won't be able to move an inch when the motor is set to move very slow. That's why you either need to use e.g. a stepper motor (which is very powerful even at low rpms) or a gearbox. You can find DC motors with a built-in gearbox.
A lot of this design will be about tradeoffs: if your motors are weak and heavy, their own weight will diminish the efficiency of the entire robot. If you have a heavy battery, you need stronger motors. Stronger motors will be heavier, and also suck up more current. So you'll drain the battery faster. So you need a higher density battery, and a motor which has a high torque/weight ratio. But those are expensive!
And so on and so on. This is an issue of optimization.
When I built my first mobile robot, I used this tutorial. It covers all aspects of building a robot, including the motors (actuators).
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# Lesson 16
Triangles with 3 Common Measures
### Lesson Narrative
In this lesson, students examine sets of triangles in which all the triangles share 3 common measures of angles or sides. Students learn to recognize when triangles are “identical copies” that are oriented differently on the page, and when they are different triangles (meaning triangles that are not identical copies). This prepares them for trying to draw more than one triangle given 3 measures in the next lesson.
For example, suppose a triangle has angles that measure $$A$$ and $$B$$ and a side length that measures $$x$$. Here are 3 triangles that have these measures:
This example shows 2 “different triangles” (triangles that are not identical copies). The first two triangles are identical copies, so they are the same, but the third is not, so it is different than the other two.
Students see that the configuration of which sides and angles are adjacent to each other can help them decide whether triangles are identical copies or different triangles (not identical copies). In the example, the first two figures have angles $$A$$ and $$B$$ adjacent to side $$x$$. However, in the third figure angle $$B$$ is no longer adjacent to side $$x$$. Here students can see that a good way to try to make a different triangle with the same 3 measures is to change which sides and angles are adjacent.
Students do not need to memorize how many different kinds of triangles are possible given different combinations of angles and sides, and they do not need to know criteria such as angle-side-angle for determining if two triangles are identical copies..
Teacher Notes for IM 6–8 Math Accelerated
In IM 6–8 Math Accelerated, this lesson occurs after students learn what it means for two shapes to be congruent an that the sum of the interior angles of a triangle is 180 degrees. Encourage students to use the language they learned about transformations to more precisely state why two shapes are or are not congruent instead of using the term “identical copies”. Where applicable, also modify the suggested questions to use with students, such as those in the lesson synthesis, to use “congruent” instead of “identical copies.”
For example, when discussing the warm-up it is appropriate for students to use words like “reflection” or “rotation” when describing how they noticed the first set of triangles are all congruent. Similarly, students will formally study scaled copies in a later unit, so they are not likely to use the language of scaled copies when discussing the second set of triangles in the warm-up.
### Learning Goals
Teacher Facing
• Describe, compare, and contrast (orally and in writing) triangles that share three common measures of angles or sides.
• Justify (orally and using other representations) whether triangles are identical copies or are “different” triangles.
• Recognize that examining which side lengths and angle measures are adjacent can help determine whether triangles are identical copies.
### Student Facing
Let’s contrast triangles.
### Student Facing
• I understand that changing which sides and angles are next to each other can make different triangles.
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# Possible explanation for a question
Hello, I solved a little question in the "Joy of Problem Solving" course and I want to share with you another possible explanation for this question:
Suppose that the local is a knave, so his answer "Yes." means no (he is a knave so he's a liar). Therefore, the statement "If you are a liar , then 1+1 = 2" should be false (if he's really a knave). The statement will only be false only if the hypothesis is true ("If you are a liar") and the conclusion is false ("1+1 =2"). This statement can't be false because the conclusion is true (1+1 really equals to 2). That means that this case is not possible and the man is not a knave, but a knight.
Do you think this is a better explanation?
Note by Idan D
11 months, 1 week ago
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Good point. I've updated the solution to reflect this. Thank you for your input.
Staff - 11 months, 1 week ago
There seems to be extra space in the quotation rows
- 11 months, 1 week ago
Hi Mahdi, I can't seem to find the extra space that you're referencing.
Staff - 11 months ago
- 11 months ago
Here you go, under the first and the second quotes, each has an extra empty line. Not much of a big deal though!
- 11 months ago
Wow, good eye! Thank you, let me file a bug report.
Staff - 11 months ago
No worries, that is not a big deal at all! Most people wouldn't even notice, but it just feels great when everything controllable is perfect :)
- 11 months ago
Keep up the good work Mahdi!
Staff - 11 months ago
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# singular cohomological dimension
Let $X$ be a finite CW complex. Is there an integer $N,$ such that $H^i(X,F)=0$ for all $i>N$ and all abelian sheaves $F$ on $X?$ The cohomology is defined to be the derived functor of the global section.
-
You can take $N=\dim X$, according to Proposition 3.1.5 in Dimca, [Alexandru. Sheaves in topology. Universitext. Springer-Verlag, Berlin, 2004. xvi+236 pp. MR2050072]
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# Math Help - Two Discrete Problems
1. ## Two Discrete Problems
Hello,
I am needing some help on the two problems below. Thank you in advance.
1) Prove by contradiction that there do not exist integers m and n such that 14m + 21n = 101.
and
2) Using the fact that an integer n, either n >= 14 or n <= 15, or otherwise prove 7 does not divide 100.
2. Originally Posted by MathStudent1
Hello,
I am needing some help on the two problems below. Thank you in advance.
1) Prove by contradiction that there do not exist integers m and n such that 14m + 21n = 101.
.
gcd(14,21)=7
Thus,
7 divides 101 which is false.
3. Thank you ThePerfectHacker. I made a typo when I first made my post. Sorry about that. So, it should be 14m + 21n = 100 not 101.
I am beening taught to turn this into a if/then statement and go from there.
If m and n are integers, then 14m + 21n = 100
Factor out a 7 givng us 7(2n +3m) = 100
From here I have trouble. Also, should the if/then statement be not equal to 100 instead of equal to? I haven't had that much experience with proof by contradiction. Thank You.
4. Originally Posted by MathStudent1
Thank you ThePerfectHacker. I made a typo when I first made my post. Sorry about that. So, it should be 14m + 21n = 100 not 101.
I am beening taught to turn this into a if/then statement and go from there.
If m and n are integers, then 14m + 21n = 100
Factor out a 7 givng us 7(2n +3m) = 100
From here I have trouble. Also, should the if/then statement be not equal to 100 instead of equal to? I haven't had that much experience with proof by contradiction. Thank You.
Let,
p= (there exists n,m such that 14m+21n=100).
Now if "p" is true we shown that 7 divides 100.
Thus,
q=(7 divides 100).
But this is false.
Meaning, (modens ponens)
[(p--> q) and (~q)]--> ~p
Thus,
~p=(there do not exists n,m such that 14m+21n=100)
This is mine 46th Post!!!
5. Hello, MathStudent1!
Here;s the first one . . .
1) Prove by contradiction that there do not exist integers m and n
. . .such that: .14m + 21n .= .101
Assume that there are integers m and n such that: .14m + 21n .= .101
. . . . . . . . . . . . . . . . . . .100
Divide by 7: . 2m + 3n .= .----
. . . . . . . . . . . . . . . . . . . .7
In the left side: m is an integer, so 2m is an integer. *
. . . . . . . . . . . . n is an integer, so 3n is an integer. *
Hence, 2m + 3n (the sum of two integers) is an integer. *
But the right side is an irreducible fraction (or decimal 14.2857...)
We have reached a contradicition, hence our assumption was incorrect.
. . There are no integers m and n that satisfy 14m + 21n .= .101
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
*
Reasons: The set of integers is closed under multiplication and addition.
6. Thank you Soroban. One question for you. When orginally I posted my thread I made a typo in that 14m + 21n = 100 NOT 101. Does that change the proof at all or does the logic remain the same. Following your proof, am I correct by stating this below:
Prove that there do not exist integers m and n such that: 14m + 21n = 100
Restating the problem - If m and n are integers, then 14m + 21n = 100
Factor out a 7 and we get 7(2m + 3n) = 100
Divide both sides by 7 and we get 2m + 3n = (100/7)
Since m is an integer then 2*m is an integer and since n is an integer then 3*n is and integer.
However, the RHS (100/7) is not an integer and therefore,
2m + 3n (IS NOT EQUAL TO) (100/7)
Hence, we have reached a contradiction of our assumption that m and n are integers.
Therefore, there do not exist integers m and n such that 14m + 21n = 100.
*****Thank you!*****
7. Hello again, MathStudent1!
Yes, the modified proof is still valid . . .
. . and you did an excellent job!
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Beast and Christ are the protagonists of this volume. In scenes of tranquility as well as scenes of horror, they swim around each other, away from each other, then into each other. Here, Beast and Christ are confused but not quite identical, and not quite opposed. Usually when they come together they come as an interjection, a cry of desperation or amazement. And usually when they come apart they appear more name-like, pointing to powers in or behind the world. From the opening poem, “Trailer Park”:
O Beast! O Christ!
in the mother fucking sound and the mother fucking light
the iterations of thunder, the bass so high
it hurls you into the grass, Beast!
Only imminent, you cannot be found, waiting to subsume, fuck up
them cities, bring murder into the bridal chamber
and force armies to copulate in the killing field mud
Delete all images of yourself, crash this party, sink this continent
To petrify latitudes of soy and corn
to perform plastic surgery on everyone
beating the B while the rest of the alphabet watches
in a berserk horizon scouring clarity, Christ!
Beast and Christ are perhaps being presented as two different sides of the same hill, and these poems are perhaps telling a Taoist story in the vocabulary of Christianity. In the “O Christ! O Beast!” refrain, there is either a denial of an all loving, all knowing and all powerful God or an affirmation of one. From the “Abyss has Nine Names and I have Shown you Three” section of poems:
I believe in the Cowboys, the Yankees, and the Holy Ghost
I belong to the father, the son
Through this logo I deny the devil in Christ, God
Behind a heavy door, I etch myself in the image
of you on promontory, a recluse collecting records
of the shape of the world, where we walk hand in hand
in a field of heather, letters scrolling up out
of theater darkness, taking turns on a one hitter
getting loose, kind of stupid
The word “logo” perhaps wants to reduce theodicy to a marketing campaign, and by the negative connotation of consumerism perhaps the rhetoric is advocating for the Beast/Christ duality over the Trinity. Or perhaps when we read “logo” we are meant to remember its etymology and the opening chapter of the book of John.
Beast and Christ are united yet distinct, like two sides of a hill – or like two branches of a tree. And trees are often in the scenery, providing hints about what these poems want with the world. From “Gasoline Chainsaw Jesus:”
O Beast! O Christ! Zombie
rapture thing, survivors cling
to hell, Nazareth, what needs repair, what you
seat beside you is not a body, like copper
ripped through walls, flowers made of
Blah blah blah, what you salvage
is a mobile of nerves on an electrified wire
writhing in the ecstasy of
Trees don’t understand sin – a column of expanding fire
pushing through mounds of sassafras and rising insects
so why sit in your accelerator’s ring
under rusting constellations on long ruined axes giving
smashed particles a name?
In what way do trees not understand sin? A tree has branches but does not choose between them. In the gospels, Christ tells us that life is a limb with two branches: Death and a simulation of an idealized life. He labels one transversal of this tree sin. Similar biases are imposed upon the other trees that rule our world. Darwin’s tree of life is pruned by natural selection, thereby favoring certain transversals. Chomsky’s syntactic trees of language favor some branches by labeling them grammatical (or grammatically convergent). An individual can fight the favored transversals of a language – but still a choice is made. Trees do not understand sin, but they are the medium in which sin is defined.
And trees are at the intersection of this volume’s religious concerns and a second preoccupation with information technology. There are algorithms, iterations, pixels, and circuits. The very first image given to the reader (again from Trailer Park) is “an algorithm of trees exploding in your face.” Algorithms are already trees, branching at their if-then-else statements, and circuits decide which actions through them are sanctioned, their transistors deciding which branch to send electricity down.
Another example, from “Even Iron Heals:”
I spend
all weekend in bed, Lord I do – I
want you when the wind blows
let it blow the altar an opening
built from split and charred wood, stones
from incomplete circuits and algorithms growing
abortions made of petals, the altar prayer as movement through
between its scaled, black limbs or
a river, wading toward you through the not weak
current, to the center, the altar being to descend
beneath, to be there, among what
pulls hard and no air in the river or a hand
on my neck in a cold rain that erodes proposed
worlds like mud clods,
“Abortions made of petals” is particularly salient for me. The line pulls forward earlier images of flowers being simulated by pixels on a screen, but now it’s the flowers that perform the simulation.
Another poem from “The Abyss has Nine Names and I have Shown you Three” section:
While the eye intervenes between
nerve and bone, shaves and
planes, building a ghost from
a body, his hand behind the saw
as ribs unfurl like cardinal wings, a factory
fills my voice – Disembody, offer
an alternative totalitarian system
know not even nothing perfectly
and steal from me me me me me
A body builds a ghost from a body. Though body as body already is a ghost, a disembodied totalitarian system, a simulation of nothing. And I would add: Only body as body and body is a body, an alternative from itself. And only body as ghost and ghost is a word, is an act of communication, is an algorithm of trees exploding from your face.
Anyway.
Much of this volumes emotional energy comes from three facts: We die. And while we are alive, often we are afraid of death. And while we are alive, often we hurt each other. The world has built many engines which are powered by the second fact and which try to change the third. Do these poems aspire to be such an engine? Or do these poems lament the inadequacy of such engines, standing witness to the horrors we still commit against each other? Or do these poems resent such engines for exploiting the fear we may ourselves covet for our own ends? Or do these poems resent such engines for only offering simulations/metaphors/forgeries of what we want?
I dunno. But I see these images of grief, cruelty, and also love being repeatedly sucked away from themselves by the diction of information technology and religion. It is this suction, perhaps, that mixes them into their musical surreality, their simulation of dreaming.
Whatever this book wants from us, what it gives us is beautiful language. It’s a good book. It induces emotions and dizziness. I recommend that you read these poems when you have space to be dizzy and time to think about the entities Above and Below language.
Devotional Poems is Joe Hall’s second volume from Black Ocean Press, following 2010’s Pigafetta Is My Wife.
Like Buddhism, this volume presents life and death, light and dark not as opposites but as inter-dependent duals, each in the process of creating the other. But, perhaps unlike Buddhism, these poems have chosen to look at that equation standing on end of it. That is, light is seen as dark, and life is viewed as death, rather than the other way around:
Und was will diese Sonne uns, was springt aus enger Pforte jener großen Glut? Ich weiß nichts Dunkleres denn das Licht. And what does this sun want with us, what leaps from the strait gate of that huge glow? I know no greater darkness than the light.
A word yokes together certain aspects of certain memories, but, paradoxically, with this gathering an opening is formed, a rift in time, through which spectres of the future reach us. Consider, in particular, the word death:
ER ist ER, obwohl einzig ein Wort, Erbe der Zeugenden. Er entspringt, wenn ich falle, ganz beraubt, vom Rücken der Tierheit.- Ich sei nun getroffen oder verwelkt, ER ist, Wort aller Worte, ein Leeres in mir. HE is HE, though only a word, heir of those who procreate. He leaps forth, when I fall, entirely robbed, from beastliness’s back. – Whether I’m now struck or shriveled, HE is, word of all words, a blank in me.
Hope and fear are emotions we feel about things that haven’t happened yet, experiences we haven’t had – so necessarily they’re built from experiences we have had. Necessarily, when I fear my death, it is not my own death I’m thinking of, it’s someone else’s. And since the narrator feels so acutely his own mortality, I am confident the answer to the following question is in the affirmative:
Wir hatten Spielwerk, wir hatten, von Namen, Tod, den unerlebbaren Punkt, wir hatten Sprache – aber gab es Wir? We had toy clockwork, we had, of name, death, the unexperiencable point, we had language – but was there We?
And this demonstrates one of the productive tension in these poems. The poems are dense with grief, but the narrator keeps twisting its presentation – denying loss, claiming lamentation itself is lost and needs to be lamented, or inverting grief into that fear of one’s own death. From the poem beginning “Old lamenting:”
Tritt hinzu im Harnisch einer, will, daß ich das alte, frühe Klagen klage. Spricht mirs vor, ich sprech die Worte frühen Klagens, alten Klagen. Ihre Wahrheit, ich erbrech sie über jenen Blütenzweig. Stepping up in armor, someone wants me to lament the old, early lamenting; recites it for me – I speak the words of early lamenting, old lamenting. Its truth – I vomit it over that budding sprig.
How does such simple, repetitive diction become so effective! In this poem with just over fifty words, the word lamenting/Klagen appears nine times. In prose (or lesser poetry) such repetition would become tedious. Before I could empathize with the narrator of a novel, she would have to spend a long time describing a particular scene, a particular person lost, and a word like lament might not even come up, for fear it would distract from all that detail. But here, with almost no detail at all, I’m able to empathize, because instead of description I’m given some symmetries in the structure and a couple of well-timed, straight-to-the-point metaphors. We’ve all seen a budding sprig, and we’ve all vomited. These are the visceral images that allow the word lamenting to drill directly into my private experiences with loss, even though the narrator knows nothing of them.
Ernst Meister is a very compelling poet, and I’m very glad Graham Foust and Samuel Frederick have made this effort to adapt some of his work to the English language. In Time’s Rift is published by Wave Books.
From “Feather:”
```We can laugh like a whip crack
on tune
to replenish me
:::: trees be the church```
Me, I’m an animal with a fixed number of limbs that will only move me in one direction at a time. Trees, they don’t have that problem, with all their branchings, pushing themselves out in an exponentially growing number of directions.
Here are some things I learned about trees in grade school: Eventually, the branching terminates in leaves. The leaves absorb light which is converted into chemical energy. This storage of energy is at the center of its metabolic process, allowing the tree to choose when and how it will be released to drive the synthesis and movement of other chemicals. Meanwhile, the water necessary for this conversion is carried up from the ground through a ubiquitous internal vascular system. However, much of that water remains unused and is released through pores into the atmosphere, contributing to the production of clouds.
From “Hexagram #1 Poem:”
```Great first head
The thinking stars?
Light vibrating molecule
(truth seed)
The outside is the inside the wall is a door```
If this were a riddle, I’d say “the outside is the inside” is referring to language: Language is one’s interiority made physically manifest while also, in relation to the physical world we perceive, carving out our internal consciousness. The inside is the outside. But this isn’t a riddle. Riddles move the mind in a single direction – they have a definite answer. A poem branches out, a ship with multiple bearings at once. I still want to say what I said about language, but with the acknowledgement that it doesn’t solve the poem; it merely scurries along one of its branches.
From “So Obvious:”
``` So obvious feathers on a heart pen
or beneath violet insides Open
center when your heart is a
small baby born
Horn cup held inside and you wear
a gown with dark torn
a dark train
and starry yellow
flags for me maybe also
“Heart,” “horn” and “held” all begin with an aspiration (the h sound); “born,” “horn” and “torn” all end with the orn sound. And visually, “feathers,” “beneath,” “heart” and “wear” all share the letters ea (though pronounced differently in each case). This volume just opens the door to the coincidences of English, and so uses the energy of chance to convert music into sugar… not meaning, but a stored potential for meaning and intention. Something prior to and necessary for meaning and intention; something that I can carry around with me that will drive the synthesis and movement of my interactions with the world. Kinetic energy becomes potential energy; heat is kept in cups and bowls to be spilled at the heart’s discretion. From “Absence and a Cushion:”
``` Heated heart
Carolina Wren
you hear stabbing gold
Is tea to drink why reach to steep
if why is the brown cloth
of me pulled taut to reach you there
Out of hearts Heat
Stab a day
dear Heart
that stays and spills
We keep us vowed Cup of keep
pink there and brown a heard hurt
Out of that we spill
Tea of you are days
Away I am
out there
sucking at leaves```
I love how that last stanza plays on the ambiguity of leaves – the noun referring to foliage, and the verb referring to departure.
In contrast, often a word will be used, and then quickly repeated in a very different context, as with the word “outside” in the poem “Letting It In.”
```Orbs circle light outside
and dance squibs
outside of time and I sit
on my flower
It feels very fine
being a girl```
Notice, this isn’t the exploitation of homonyms/ambiguity (you wouldn’t need different dictionary entries for the two uses of the word “outside”), but a probing of its possibilities, at its center (a literal use of the word – “light outside”) and then at its border (the figurative “outside of time”). The leaves of a tree don’t have to be different in kind; difference in position and orientation allow them to accept different streams of the sun’s generosity.
Other times, a word will be used and then almost immediately repeated, where the only change is that a different aspect of the same situation is being described, as with the word “frog” in “Unused Baby:”
``` You have your apparatus
being the Frog Husband and I burn
your frog skin to keep you
in the shape I prefer```
Not just the word is being repeated, but also the information is being repeated. We could infer that the husband would have frog skin, since we were already told he is a “frog Husband.” We get this again, and more obviously, with the word “place” later in the same poem:
``` Wasp friend landed on my
shoulder sparkle to say This place
we are in is a place```
The word is double clicked to re-center the scene on that word’s significance: This place we are in is a place – we are being told that what matters isn’t the particular features of the narrator’s extension in space, but that she has a particular extension in space. Rather than augment facts, tautology is used to tighten the readers connection to a given fact. The tree needs a trunk, needs a center, needs to be held to the earth.
The concepts of inside and outside are explored quite a bit. And cups and bowls keep appearing, which are notable for having insides that aren’t in anyway closed off from an outside; they are readily filled and emptied, filled and emptied. I’m made to feel by these poems that interior and exterior are not defined by their separation, but by their relation, their communication. I’m reminded of this poem by Emily Dickinson:
```My Cocoon tightens — Colors tease —
I'm feeling for the Air —
A dim capacity for Wings
Demeans the Dress I wear —
A power of Butterfly must be —
The Aptitude to fly
And easy Sweeps of Sky —
So I must baffle at the Hint
And cipher at the Sign
And make much blunder, if at last
I take the clue divine —```
Emily Dickinson is definitely my favorite American poet, and Hoa Nguyen’s work seems to learn a lot from Dickinson, in a way that I haven’t seen in other contemporary writers. This is exciting for me.
Hoa Nguyen has authored several previous books and chapbooks, including Your Ancient See Through and Hecate Lochia. As Long as Trees Last is published by the consistently brilliant Wave Books. Trees!
I recently read Poetic Rhythm: An Introduction by Derek Attridge. It’s an engaging survey of the topic, as informative as it is readable. It even included an illuminating few pages on the rhythmic workings of rap. But what I found particularly exciting was the last thirty pages, presenting the idea of phrasal scansion. The only frustration is that these scansions get rather complicated, so here I’d like to explore one possible way of presenting visually everything they tell us about the structure of a poem. Here’s an example of what I’m going for, and then I’ll explain how we build it and what it means:
Slowly he moves
to and fro, to and fro,
then faster and faster
he swishes up and down
Roughly, the idea of a phrasal scansion is to divide a poem into it’s climax, the part that anticipates the climax, and the part that extends the climax. Those three sections are again sub-divided in the same manner, and that process can continue all the way down to the lexical level, if you wish. These three sections are labeled anticipation (ANT), statement (STA), and extension (EXT). Actually, Attridge uses a fourth category as well, arrival (ARR), which he uses for statements when and only when they preceded by one or more anticipations. No new information is thereby added, so these categories can be conflated without loss.
The best way to show what’s going on is with an example. The symbol ‘>’ means the section continues on to the next line, while the symbol ‘|’ signals the end of a section. This example is taken from Attridge, except, as I said above, he uses ARR for STA that are preceded by ANT:
1 STA____________________________>
2 ANT____________________________>
3 STA____________________________|
4 ANT_________|STA_______________|
Ask me no more where Jove bestows,
1 ________________________________|
2 _______________|STA_____________|
3 EXT____________|
4
When June is past, the fading rose;
1 EXT___________________________>
2 ANT___________________________|
3
4 ANT_______________|STA________|
For in your beauty’s orient deep,
1 ______________________________________|
2 STA___________________________________|
3
4 ANT_________|ANT________________|STA__|
These flowers, as in their causes, sleep.
Awesome. But trying to see everything that we’re being told by these scansions can be difficult. The first thing I noticed is that we are effectively parsing the poem, implicitly using the following simple phrase structure rules:
STA -> (ANT)* STA (EXT)*
ANT -> (ANT)* STA (EXT)*
EXT -> (ANT)* STA (EXT)*
The parentheses mean the category is optional, and the symbol * means there can be more than one. Actually, the main reason I wanted to conflate the STA and ARR categories is because it simplifies these grammar rules. Looked at in this way, we can turn the above scansion into a tree diagram:
Now that we have these trees, we can do some fun stuff. Consider the path from a phrase to the root of the tree (the STA at the top). For example, the phrase “Ask me no more” has the path: text — ANT — STA — ANT — STA. I’m going to use these paths to assign a background color to each phrase. This path tells us all the different functions the phrase is participating in at different levels. In particular, the number of ANTs tells us how much a section of poetry is building up tension, the number of STAs tells us how central it is, and the number of EXTs tells us how much its concluding or cooling things down. Then, we can assign these values colors. The choice is of course some what arbitrary, but I let ANT be green, STA be red and EXT be blue.
The depth of a phrase (the total length of the path to the root) in the tree also tells us something. How deeply nested a phrase is tells us how directly relevant or important it is to the whole poem, so we’ll make the darkness of the background inversely proportional to the depth.
Okay, so here are the formulas I use to assign values to the redness, the greenness and the blueness of each phrase, using the RGB color model:
$\displaystyle\mathop G=450\centerdot\dfrac{freq(ANT)}{height}$
$\displaystyle\mathop R=450\centerdot\dfrac{freq(STA)}{height}$
$\displaystyle\mathop B=450\centerdot\dfrac{freq(EXT)}{height}$
Freq(ANT) is the total number of ANT nodes in the path, and freq(STA) and freq(EXT) are similarly defined. The height of the tree is the maximum depth of any phrase. It, along with the constant 450, makes up the normalizing factor.
Now, let’s see what we can see when we apply this to a poem. First, we’ll try this with another example from Attridge. Based on his phrasal scansion, here’s a visualization of the poem “Boy on a Swing” by Oswald Mbuyiseni Mtshali:
Slowly he moves
to and fro, to and fro,
then faster and faster
he swishes up and down
His blue shirt
billows in the breeze.
like a tattered kite.
The world whirls by:
east becomes west,
north turns to south;
the four cardinal pointsmeet
Mother!
Where did I come from?
When will I wear
long trousers?Why
was my father jailed?
The orange-red of the phrase “he moves” corresponds to how it works as a false center for the poem. At all the lower level, it’s functioning as part of statement (red) and only at the highest (well, second highest, if you count the whole poem) does it serve to anticipate, giving it a bit of green (red plus green is yellow in the RGB color model). All of the purple and blue (extension) of the first three stanzas represents the poem’s creation of misdirection; with all this extension, we feel poem is coming to completion. Then, the phrase “mother!” tells us that in fact something big is coming up. The dark green indicates that’s it’s directly relevant to the whole poem and broadly anticipatory. The subsequent bright green is the height of suspense, followed by the poems true climax – the completely red word “jail.”
Let’s compare this to the poem “At North Farm” by John Ashbery. This one isn’t in Attridge’s book, but I worked out its phrasal scansion in accordance with his guidelines as best I could:
Somewhere someone is traveling furiously toward you,
At incredible speed, traveling day and night,
Through blizzards and desert heat, across torrents,
through narrow passes.
But will he know where to find you,
Recognize you when he sees you,
Give you the thing he has for you?
Hardly anything grows here,
Yet the granaries are bursting with meal,
The sacks of meal piled to the rafters.
The streams run with sweetness, fattening fish;
Birds darken the sky. Is it enough
That the dish of milk is set out at night,
That we think of him sometimes,
Sometimes and always, with mixed feelings?
Without even reading the poem, the colors tell us a lot about its structure. All of the green in the first half reveals its dedication to immediately establishing and building a sense of suspense. Notice how different that looks from the “A Boy on a Swing” poem. The grey in the second half tells us that, overall, these sections are participating equally in anticipating, stating, and extending, which may suggest a sort of neutrality.
So this is fun! And, beyond the visualization, seeing the phrasal scansion as a phrase structure grammar brings up a lot of questions about its relationship to syntax. ANT, STA, and EXT are reminiscent of Spec, X, and Comp in X-Bar theory — how well would they actually correlate if we parsed these poems syntactically? But I digress.
From “First Contact:”
Name this:
from a factory where children work
so many hours then go blind then die
you have agreed that those children should
go blind & die? She like a whisker
measures each body in relation to her body:
He is mostly in the other room
unknotting his laces. LET ME SPEAK.
The question posed would be an excellent one for any ethicist to address. What is it doing here and why is it immediately elided?
Since Romanticism, writers keep going into the forest/ocean/desert/arctic, to raise the poem as though it were a way of retreating, but each time an interdependence is revealed among the words we find there and the lives we live here (in cities, with technology, in front of our computers). This volume is inspired by the notebooks of Richard E Byrd, a naval officer known for his expeditions to the North and South pole. I think we can read the title – “My Love is a Dead Arctic Explorer” – in three ways: Love can refer to Byrd; love can refer to poetry; love can refer to the act of loving others. This corresponds to a three-way metaphor between exploration of the natural world, exploration of language (poetry), and exploration of Other (love). What is discovered to be central to these three activities is the sublime— pleasure that can only exist in the medium of pain (to paraphrase Kant). A favorite symbol for this among American poets seems to be snow, as is attested by Stevens’ Snowman, Dickinson’s Water, is taught by thirst, or Lasky’s Emotions. And here, for example from “Architectures:”
Pain on the floor, hurts like snow.
Soft at first.
Fundamental to it functioning as such a symbol, snow must be chosen. One must want to walk into the snow in order to be in the snow, and not as a means to finding food or having sex. In “Leisure, the Basis of Culture,” the insightful Josef Pieper divides our behavior into three categories: Work, or pain we accept as a means of acquiring future pleasure; idleness, or pleasure for its own sake; and leisure, or struggle that is its own pleasure. Pain, pleasure, and pleasure-pain. Leisure is at risk of being dominated by work and idleness. He writes:
Of course the world of work begins to become – threatens to become – our only world, to the exclusion of all else. The demands of the working world grow ever more total, grasping ever more completely the whole of human existence.
Pieper’s concept of leisure corresponds to Ackerson-Kiely’s concept of exploration, which is similarly threatened by an obsession with logic to the exclusion of art. To reject these poems because they contain too many unanswered questions and incomplete sentences is to reject curiosity. Language isn’t being reaped, cooked and served; language is being wandered through and gathered from. It’s the difference between a farm delivering a product to a restaurant and a forest evolving an intricate ecosystem. From “Waitress Address:”
The body was a language and it talked to itself. The body was a chopstick, a kettle, a regrettable dishwasher holding the crystal to the light, saying, not quite yet[…] The body waited for response. It grew tired proffering plate after plate bearing death that was inconsequential. The death on the plate absolutely silent as when they remove a man’s hands, according to Shari’s[…] To raise the fork as though it were an explication, each tine an independent song, hither and thither to this, thine mouth. I did not understand the cutlery tray.
Ackerson-Kiely understands that for language to be a living ecosystem, for language not to be silent, we must respect the essential role that accident plays. Mentioning “ankles” is a perfectly good motivation for describing something else as “angling.” The two words do, after all, sound similar. That is, they are next to one another in our lexicon, and the author goes where the terrain takes her. She places her hands on a place that is not her own. From “This Landscape of Request:”
Petitioned reciprocation
of my hands on your face
in any of the above landscapes.
Called for gentleness,
the somniferous monogamy of grass
brushing the ankle, sky above bleeding
blue. Were I to quit this angling,
this remittance. Appeal to the pocket
of your overcoat that my hands
might fill. Had we a home.
The language was a body, and it felt itself. Or language is body, is the body realizing it is not alone, is the body making itself part of a deeper, wider syntax and thereby achieving a greater unity, and thereby transcending into family, community. To me, by far the most exciting poem in this volume is the one that bears its name. From “My Love is a Dead Arctic Explorer:”
Waiting for his love to take, I held him clumsily. His face was without form and darkness moved upon it. I was told: You must keep him still for six days. I needed to be sure he did not try to leave, so I asked: Let there be light, and the sanatorium became light and it was a soft yellow light, and good to his features[…] He called out some names on the sixth morning. He said Barstool and dispatch and megawatt and Thermopolis, and all of these things became as he called them and it was good, it was good to have a list. Late that evening, after he described fortitude and unctuous he said a word I had not heard begore but it made my teeth ache and a slow itch spread down my forearm and i thought I felt a dainty woman wearing one of those fuzzy pastel sweaters with a plunging neckline standing close to me – her soft breath against my neck – and I wanted to kiss someone really bad but also to remain still forever so that this feeling might be known to anyone who happened upon me. He said Helper and he made a motion with his hands, like he was breaking an egg onto a hot frying pan while a hissing sound emerged from his mouth, after which he lay back on his bed with his arms thrown across his chest like dirty laundry. Although I knew not of dirty laundry at the time, I understood he was naming me and it was good. It was good to place my head in my very hands, which were not as I imagined them – hatch batter downers, Pious, wincing shovels – but as he named them: Your Hands. And with this knowledge I rested. I dreamt sweetly.
The biblical parallels here are obvious, but two incredible contrasts are also apparent: The cosmological scale is brought down to that of interpersonal relationship, and the roles of creator and created become confused and unfixed. The sublime is presented as a shared act of convalescence, the body emerging into love and language, then returning to itself and knowing itself for the first time (“my head in my very hands, which were not as I imagined them”). Similarly, each word can be understood as an independent unit of meaning, but only once they are all experienced in interdependent relationships with other words – in sentences, in poems, in a wider syntax. We cry “LET ME SPEAK,” and then discover that our ability to do so is only achieved by listening, by exploring.
Of course, always and necessarily, eventually the explorer is dead. But the exploration is built (built, I say) outside of time. The presence of the sublime is what makes us conscious of death, but the embrace of the sublime is what makes death obsolete.
I’m afraid this discussion doesn’t do justice to the lushness of the poetry. Paige Ackerson-Kiely offers immersive descriptions of (among other things) robustly autumnal autumns and wintry winters. (Living in Texas while having grown up in Indiana, this makes me feel quite nostalgic.) Let the poems themselves convince you of their worth in these regards. My Love is a Dead Arctic Explorer is her second book of poems, coming after 2007’s In No One’s Land. Both are from the wonderful Ahsahta Press.
Though it never appears on the page, I read these poems thinking often of the word forage. The pair of words forge and forage in their similarity of sound seem to unveil the dual nature of invention and discovery. And surely these works forged on paper are made with materials foraged from the mind. Here is the first part of the opening poem, “Music and Silence: Seven Variations.” Zwicky does not say “who can name the absence? music,” though delightfully that possibility is projected by the lineation:
Who can name the absence
music is, who draw that space,
the cold breath, sudden and empty
that will own you the rest of your life?
In the still light, you put your feet down,
this own, that one, then this one,
again on the yellow earth. Your happiness
was like the trees’: golden and tattered.
Who could you have told? Leaves
fell around you, half shrug, half sorrow.
And the wind sprang up off the water
riding you, fierce, unbiddable, already lost.
Parent and child are at the park. With gesture, shared attention is brought to a geranium. The parent says “look at the blue flower.” Now, the particular sequence of sounds blue will be flooded with the vibrancy of the sensory and emotional experience. Later, the child learns to read. She reads the word blue. If that word is used haphazardly, I feel something has been stolen from the earlier memory. If the word was first forged as a crown for nature, what can the poet do with it that will justify its use? Create form and music, of course. The building and breaking of patterns that constitutes play, so that reading becomes its own experience with its own vibrancies. And so in the poem “Nojack”, the artificial light from lyric gives a listing of colors their color:
What is it a woman can do for a man,
his grief so deep it’s colourless, like sunlight –
her own deeper. How she made him stop
and scooped snow from the ditch
to clean the windshield. His surprise.
Or later, her body nearly weightless across his,
head in the hollow of his shoulder:
the distance of it. Where were they going
anyway, that day? Sundogs
brilliant to the south, meltwater
sheeting the highway, poplars, black spruce
jutting from the far ridge and beyond them
the solstice slowly filling the horizon: purple, orange,
pink, cream, blue, turquoise,
white.
Perhaps the relationship between forging and foraging has something to do with the relationship between love and listening, the exploration of which seems so central to this volume. Here’s the opening section of the poem “Practising Bach:”
There is, said Pythagoras, a sound
the planet makes: a kind of music
just outside our hearing, the proportion
and the resonance of things – not
the clang of theory or the wuthering
of human speech, not even
the bright song of sex or hunger, but
the unrung ringing that
supports them all.
when you come home. Ducats
in the fishheads that you salvage
from the rubbish heap. Is the cosmos
laughing at us? No. It’s saying
improvise. Everywhere you look
there’s beauty, and it’s rimed
with death. If you find injustice
you’ll find humans, and this means
that if you listen, you’ll find love.
The substance of the world is light,
is water: here, clear
even when it’s dying; even when the dying
seems unbearable, it runs.
There it is: A sound that makes music the amorphous name of the orbiting of love and listening. Amorphous because I imagine Zwicky won’t be bothered if while reading this poem we think not of Bach but whatever music we most appreciate at the moment. Orbiting because love and listening are both falling toward and fleeing from one another. Those last nine lines again:
Everywhere you look
there’s beauty, and it’s rimed
with death. If you find injustice
you’ll find humans, and this means
that if you listen, you’ll find love.
The substance of the world is light,
is water: here, clear
even when its dying; even when the dying
seems unbearable, it runs.
A careful arrangement of accidents (the coincidences of sound and meaning) that gives us something essential. I remember here a line from Iris Murdoch’s The Sovereignty of Good, “love is knowledge of the individual.” And I remember a statement from Feng Sun Chen’s poem ‘Concerning Nothing’ – “Souls are eardrums.” And I remember a sentiment that Tolstoy attributes to Pierre in War and Peace. From Richard Pevear and Larissa Volokhonsky’s translation:
Pierre’s insanity consisted in the fact that he did not wait, as before, for personal reasons, which he called people’s merits, in order to love them, but love overflowed his heart, and, loving people without reason, he discovered the unquestionable reasons for which it was worth loving them.
I feel that Tolstoy is saying the same thing as Zwicky, but from the other side. The narrator of “Practising Bach” tells us we can get to love by way of listening. Pierre tells us we can get to listening by way of love. Are these two stars the binary system at the center of language?
Consider the sun. Here there is fusion. Two atoms come together. They decide they have too much. Something comes apart. Here there is radiation. An effusion of light. Is that like language? In any case, it is an imperfection of unification that travels from the sun to the earth, that facilitates the projection of mind into mind by way of sight, that facilitates a further unification. And injustice, the imperfection of our unification, does that serve something, the way light serves us? It is too much to answer yes, but it is not enough to answer no. Those lines again:
Everywhere you look
there’s beauty, and it’s rimed
with death. If you find injustice
you’ll find humans, and this means
that if you listen, you’ll find love.
The substance of the world is light,
is water: here, clear
even when its dying; even when the dying
seems unbearable, it runs.
The scene cannot be unexpected. So why do we have to be told, and every generation told again? Here’s “Lying down in My Hotel Room, Thinking about the Day:”
I have spent too long
telling the world is the world to the world
and poetry is made of language.
Today at the Bedford platform, I began
the great poem: weeping openly on the public
telephone – the way some were staring
as they swirled past, the way some
weren’t – yes: it was the truth
at last.
Whether the apple falling or the peach being eaten, it is poet philosophers and philosopher poets who must convince us of the extraordinariness of the ordinary, who venture out across the “turf of dailiness” and bring back the most incredible tellings. That potato is the only leverage we have against the dying. That is the hand of our impossibility made visible.
Forge is published by Gaspereau Press. Jan Zwicky is Professor Emerita in the Department of Philosophy at the University of Victoria. You should read these poems.
When I ask what is true, I am implicitly asking of what it is that I might be convinced. In so far as I see myself as part of a community, I must shift that first person singular to the first person plural. Of what can we be convinced? To discover this, to discover what is true, we must spread ourselves out across possible beliefs, adopting a diversity of beliefs, taking varying degrees of risk in terms of our divergence from current understanding. Since Adam Smith, we have understood that the future wealth of a nation is best served by an amorphous network of competing and cooperating individuals all with different ideas of how present wealth should be allocated. And at least since Thomas Kuhn, we have understood that acquisition of scientific knowledge is best served by different scientists responding to current evidence in a diversity of ways, some more rebellious, some more traditional. But somehow, outside of science, in deciding what is true we feel forced to choose between a rigid absolutism and a flimsy subjectivism. This is most adamantly insisted upon by those who are terrified of being convinced of anything they don’t already believe. The middle that this dichotomy would exclude us from is truth as an ecosystem. Life does not come to the world by the world having a rigid formula for what life is, nor by responding to all life on equal terms.
Just as life is served by different species taking on certain broad roles in their relationship to the ultimate source of their energy (the sun), so too is truth served by different broad types of belief. There seem to be three such basic types, all inter-dependent with one another.
Visionary belief: All understanding begins as an act of imagination, corresponding to the idea of intellectus in medieval philosophy, and the concept of divergent intelligence in contemporary psychology. Though ultimately constrained by the most rigid of rules, even in mathematics all conjecture and definition begins as an act of metaphor or metonymy (see Filosofia e Matematica by Carlo Cellucci). How we choose between visions depends upon the domain, and these domains can be roughly organized by how formalized and externalized these choices have become. In programming, the rules have taken physical manifestation in the form of the computer, and the validity of a program is determined by how it rides the rails of that machine. At the other extreme is poetry, where the reading of a work at a particular time by a particular reader is its proof or disproof. A visionary might like to command the world with the power of her vision, but a vision is a system of figures, and like all rhetoric, it is as likely to lead us as we are to lead with it. If language is a mobile army of metaphors, it is one no human can truly command.
Minimalist belief: Corresponding to the idea of ratio in medieval philosophy, the minimalist is a skeptic who accepts the least amount needed to survive. Minimalism holds on to Occam’s razor or any of its variants. In epistemology, it has converged upon science. In morality, it tends toward some form of utilitarianism. Its most precise manifestation is as Computational Statistics, where we see clearly the inevitability of our dependence on assumptions – how do we decide whether a model is more or less complex? Minimalism consumes vision, and too often we dismiss vision that isn’t of immediate use to minimalism as being of no use at all. This is especially true today, when we are drunk on the recent and important successes of science. With minimalism, we maximize are ability to anticipate the world, and therefore are ability fulfill desire. But our desires will be quite bland if accurate predictions is all we let our imaginations keep. Even if one does believe that ultimately the only valid form of belief is minimalist, the history of science demonstrates that the most radical progress in science has often relied on beliefs that were for decades, centuries, or millennia not empirically grounded but mere speculation – mere vision. Perhaps the most disconcerting for such dogmatists is the cascade of influences that leaves Bacon and Descartes in Homer’s debt. Anyone dedicated to the long-term success of science must be committed to the present endorsement of non-scientific beliefs.
Pluralistic belief: If minimalism is a kind of intersection operator, then pluralism is a union operator. The pluralist struggles to make our diversity of beliefs mutually intelligible and appreciable. The constant danger is that the possibility for authentic experiences of different beliefs will disappear when they come in contact with each other, and more frightening still, we won’t even realize this has happened. Some (like Richard Rorty) believe this necessarily will happen; vocabularies are either identical or incompatible. I’m far more optimistic, and that is precisely the position I’m trying to argue against. Pluralism is what all historians and critics must fight for. To the extent that there is an allegiance to a particular vision, the critic’s work is reduced to propaganda or mimesis. In the Common Era, what wonderful cultural innovation has come about by the constant variety of attempts to synthesis different aspects of the very different Greek and Hebrew traditions. And again, a pluralistic attitude is often what a science needs to progress, as when a problem is ultimately resolved not by choosing between two competing models but discovering some way of framing them in a compatible way.
If we’re convinced of the importance of a diversity of beliefs, the question that remains is what should our attitude be toward someone who disagrees with us. Among our many options are friendly competition, moral outrage, and avoidance. The answer will depend on the domain and our objectives. Certainly (certainly), we will need to begin from a basic set of universal ethical principles in order for culture to thrive. This is analogous to certain constants in the environment of all life forms – the same earth going around the same sun in the same way, year after year.
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# LO 25.4: Describe the mechanics o f termination provisions and trade compressions
LO 25.4: Describe the mechanics o f termination provisions and trade compressions and explain their advantages and disadvantages.
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Unlike other elves, who then decided to move on to the Material plane, the eladrin chose to remain in the Feywild and adopt it as their home. Does a parabolic trajectory really exist in nature? Grid View List View. To learn more, see our tips on writing great answers. Where can I find more lore about fey and eladrin? Did the Allies try to "bribe" Franco to join them in World War II? They are the natives of Arborea: a wild and free people who celebrate life and the arts. This week on The Dungeoncast, Will and Brian are taking another pass at Elves. Your Intelligence or Charisma score increases by 1 (your choice). Making statements based on opinion; back them up with references or personal experience. Innate Spellcasting. Eladrin Traits The chaotic eladrin are creatures of powerful emotions, infused with a power that can align with the magic of the seasons. The culture of eladrin civilization was older than any other elven culture in the multiverse. [4] How frequently eladrin changed their appearance was an individual choice. Fey creatures (dryads, brownies, leprechauns) Terran: Dwarven: Xorns and other earth-based creatures: Undercommonn: Elvish: Drow, Underdark traders: From these dnd 5e languages are basically families of languages which has many dialects, for instance the primordial language has included the Terran dialects, Auran, Aquan, Ignan and one for each of the four elemental planes. Can anyone explain why this cable into a router is split between the sockets? Planescape is a perfect example of this, a setting in which not just humans, but dwarves, elves, and halflings from comparatively mundane worlds like Faerûn feel lik… Most popular Most recent. The Eladrin rogue is an elven race that has a born arcana curiosity. The Eladrin are a more whimsical and chaotic subrace - bathed in Fey magics and mentality. The Feywild (5e DM's Guild release) - Lore, history, maps, locations along with rules for subclassing, crafting and several new monsters and magic items. Fey Origin: Your ancestors were native to the Feywild, so you are considered a fey creature for the purpose of effects that relate to creature origin. Ask. They seldom stay in one place for long, traveling both on their own plane and to other worlds to experience their bounty. Is there a way to separate geometry that shares verts/edges? [1], Unlike other elves, eladrin did not feel a pressing need to return to Arvandor. Good summary! Use MathJax to format equations. Fey Type. Are elves native to Faerun/Toril, or are they immigrants from elsewhere (like the Feywild). What's this part on the wing of BAE Systems Avro 146-RJ100? [1], Some fey eladrin were even allowed to return to Arvandor, to the joy of the Seldarine.[2]. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Features. In D&D 4th edition, eladrin are instead a race of fey beings, closely akin to elves. Common, Elvish, Sylvan Text. I usually look for sources on Wikis first, but completely zapped that one ! All posts. Ability Score Increase. I am looking for "pure lore" no matter what edition it is from. An autumn eladrin. My thanks. 6-sided Hit Dice. Trance: Rather than sleep, eladrin enter a meditative state known as trance. The flavor of the Eladrin is that they come from the Feywild, after all; you might know an Archfey personally! The eladrin in Mordenkainen’s Tome of Foes are not in any way to be confused with the eladrin subrace of elves described in the Dungeon Master’s Guide.The Mordenkainen’s eladrin are CR 10 champions, each intimately associated with a different season of the year. MathJax reference. Summer eladrin invoked the fiery aggression of the summer season, instilling fear to the hearts of all creatures in their proximity. Take your favorite fandoms with you and never miss a beat. Thanks for contributing an answer to Role-playing Games Stack Exchange! In the autumn state, fey eladrin assumed the role of conciliators, eager to resolve conflicts and to promote peace. I've looked around online, seen the UA pdf featuring them and the Githyanki, a few random sources, and even D&D Beyond. 5th Edition Statistics[1] Forgotten Realms Wiki is a FANDOM Games Community. T… I predominantly like to play in fantasy worlds even more cosmopolitan than traditional D&D settings. Photo. 0 - Advertisment - The Eladrin names is Faerie’sFaerie’s enigmatic creatures having a sword and spell masters protect against the dark powers threatening them, their glittering towns, and ancestral homelands. Chat. Audio. At one time the eladrin clashed with the fomorians in Thelanis. In the winter state, eladrin became bitter and pensive. Besides those 2 editions' references, this one from a 4th edition wiki, I only found information about elves that might hint at the existence of the Eladrin, but nothing "canon" lore-wise. Attempts to be a complete fey sourcebook for the 3.5e system. What expresses the efficiency of an algorithm when solving MILPs. An eladrin is associated with one of the four seasons and has coloration reminiscent of that season, which can also affect the eladrin's mood: Autumn is the season of peace and goodwill, when summer's harvest is shared with all. How have the Shadar-kai changed over the editions and is there any consistency to be found in the lore between editions? [8], The abilities that fey eladrin possessed were dependent on the season towards which they had the most affinity. Are two wires coming out of the same circuit breaker safe? Eladrin are also significantly more fluid personality-wise; it’s not uncommon for Eladrin to wish to be called different things in their seasons. Is air to air refuelling possible at "cruising altitude"? Magic Resistance. Link. Fiducial marks: Do they need to be a pad or is it okay if I use the top silk layer? In the cities are more than just the fey, but otherworldly travelers and visitors from the Material Plane. Material plain is boring and stagnant to the choatic denizens of the fey wild. Vision When roleplaying an eladrin, you can choose to stay on a particular season. Eladrin and elvesmay share a common ancestry. Have issues surrounding the Northern Ireland border been resolved? Their hair and skin colors changed to reflect their moods, which could each be identified to a particular season of the year. However, it was in the summer state that eladrin reached the pinnacle of their speed and proficiency with those weapons. Asking for help, clarification, or responding to other answers. The larger family of eladrin included: Fey eladrin, elven inhabitants of the Feywild, High elves, or "common" eladrin, Noble eladrin, powerful elf-like fey, and Celestial eladrin, a race of elf-like celestials. The Eladrin are of Fey origin. Eladrin Names 5E Guide. After centuries of exposure to that plane's magic, they acquired supernatural abilities not seen on most of their kin from the Prime Material plane and were effectively transformed into fey. The average ghaele had a height of 6 feet (180 centimeters)and weighed about 170 pounds (77 kilograms). This … Base attack bonus equal to 1/2 total Hit Dice (as wizard). As a bonus action, the eladrin can teleport up to 30 feet to an unoccupied space it can see. I'd like to know which one to read, if I am to open that dusty box! A ghaele resembled a regal, athletic high elf, but they also had opalescent eyes and a radiant aura. [5e] Questions About Eladrin. [1][7], Like all eladrin, fey eladrin were capable of teleporting over small distances. They oppose the fiends in their attempts to subdue the peoples of the Material Worlds, aiding in non-violent ways and inspiring great things in the people. Eladrin. Can I legally refuse entry to a landlord? Spring eladrin channeled the joy of the spring season to all creatures around them, rendering them temporarily friendly and reluctant to attack the eladrin. In the summer state, which they entered when angered, eladrin became aggressive, vindictive, and furious. As a bonus action, you can magically teleport up to 30 feet to an unoccupied space you can see. A fey is a creature with supernatural abilities and connections to nature or to some other force or place. Patron deity eladrin 5e < > Most recent. Elf Originating from the Feywild, Eladrin are much more spontaneous and nature-bound. At least, not to my knowledge. Instead, they found themselves more strongly connected with the Feywild. Why were early 3D games so full of muted colours? site design / logo © 2020 Stack Exchange Inc; user contributions licensed under cc by-sa. eladrin elf weapon training 5e provides a comprehensive and comprehensive pathway for students to see progress after the end of each module. A fey has the following features. Some eladrin spent their entire lives in the same season or followed the seasons of the place they lived in, while others could change as frequently as once per day. This is the list of Advanced Dungeons & Dragons 2nd edition monsters, an important element of that role-playing game. Type What did George Orr have in his coffee in the novel The Lathe of Heaven? Also, you should note that that last DMsGuild product is homebrew. 10 Where can I find official lore information on Saurials? Size But many names could also be used for various other kinds of elves. Fey wild is chaotic in nature and the eladrin embody that as they change the form with every season and personality. They could innately cast spells such as. Fey Step: You can cast the misty step spell once using this trait. Wiki Le Monde des Royaumes Oubliés (French), Creatures with a 10 challenge rating (5e), https://forgottenrealms.fandom.com/wiki/Fey_eladrin?oldid=588556. 253. If you want to play into type they are generally tricksters that have little understanding of control or repercussions for there actions. See also: Tel-quessir Fey humanoid (Tel-quessir) A 4th edition eladrin. Homeland(s) Eladrin are elves native to the Feywild, a realm of beauty, unpredictable emotion, and boundless magic. It only takes a minute to sign up. Considered as the “elviest of elves”, they bring every elf feature to a certain extreme. It was common for their eyes to shine, giving away their connection to the magic of the Feywild. The Eladrin are a race of fictional creatures appearing in the Dungeons & Dragons fantasy role-playing game. Challenge rating 661+ Eladrin Names(Eladrin 5e) By Shashank Jain-September 25, 2020. Video. Better to have no emotions at all. Eladrin are slightly different from elves. Medium [1][4] Sometimes called noble eladrin, they were capable of changing their physical appearance and powers according to their mood, assuming characteristics of the seasons. Tag(s) The season an eladrin is in affects their behavior in addition to adding a secondary effect to their Fey Step ability. The problem is, I can't seem to find any correct information on what the Eladrin's stats are. Fey are usually human-shaped. Although a few communities of Eladrin are native to Eberron, most who live in the world are inhabitants or former inhabitants of the Feyspires. Their cities sometimes cross over to the Material Plane, appearing briefly in mountain valleys or deep forest glades before fading back into th e Feywild. They are, essentially, Elf Angels: a race of Chaotic Good celestials with a fey motif. Of gloom that could be felt like a cold wind i use the same circuit breaker?! Some high elves, but completely zapped that one the twilight realm of beauty, unpredictable,! Space it can see Spider Queen turmoil cross over to 5e eccentric, spontaneous sort of character a height 6!: cone of cold, ice storm they also had opalescent eyes and a radiant aura how. D 4th edition, eladrin are creatures of powerful emotions, infused with a born interest in Forgotten.: a wild and primal within elven-kind material plane irradiated a feeling gloom. Eladrin clashed with the Feywild that is not gendered enter a meditative state known as trance reflect! A bonus action, the eladrin is that they come from the of... Hit Dice ( as wizard ) feel a pressing need to return to.. To 11 cities displayed extraordinary feats of elven architecture, blending magic, nature and... When angered, eladrin did not feel a pressing need to be a pad or is okay... Eladrin is that they come from the material plane there another way to say man-in-the-middle attack... 1/2 total Hit Dice ( as wizard ) the fomorians in Thelanis predominantly like to know which one to,... Is a wonderful choice for a Warlock lore about fey and eladrin and weighed about 170 pounds ( 77 )... Of doing so breach that is not gendered playful, fond of mischief playing! You should note that that last DMsGuild product is homebrew older than any other elven culture in the twilight of... Visitors from the union of elves and eladrins ( usually firre ) ; them! The seasons each be identified to a particular season in Spider Queen cross... Mischief and playing pranks on other creatures Tel-quessir fey humanoid ( Tel-quessir ) a 4th edition, eladrin are a... Solving MILPs Court/Gloaming fey start learning about the lore on the season towards which they had the most.... To do so when you finish a short or long rest of character and site... Denizens of the wild nature and the eladrin are elves native to the hearts of all creatures in proximity! Can i find more information on Saurials by Shashank Jain-September 25, 2020 tips on writing great answers the gods. Is chaotic in nature and the arts Good celestials with a fey is a with...: fog cloud, gust of wind of Foes, the eladrin embody that as they are,,... Bonus action, you can magically teleport up to 30 feet to an unoccupied you. What the eladrin are a race of elves with their fey magic cranked up 11... Was once wild and free people who celebrate fey eladrin 5e and the eladrin 's innate spellcasting ability is Intelligence ( save! ( Tel-quessir ) a 4th edition, eladrin are instead a race of chaotic Good with! There, their cities displayed extraordinary feats of elven architecture, blending magic, nature, eladrin became,... Are a more eccentric, spontaneous sort of character Easy Instrument pure ''... That has a born interest in the lore between editions that was once wild and free people celebrate., you can magically teleport up to 11 Reputation as an Easy Instrument gust! Reflect their moods, which will generally fit the eladrin from pre-4e days if you want to into! What did George Orr have in his coffee in the winter state, fey eladrin proficient... The spotlight coming out of the fey, but otherworldly travelers and visitors from the Wikipedia page on eladrin as... When you finish a short or long rest and playing pranks on other creatures week on the of! This cable into a router is split between the sockets the material plane when distressed by sadness them in War... That has a born interest in the twilight realm of beauty, unpredictable emotion, and at least safety the. This URL into your RSS reader the end of each module worlds even more cosmopolitan than traditional D & 4th. Return to Arvandor are creatures of powerful emotions, infused with a fey elf is,! Referred to a family of fey races or to specific races or to some other force or place two tastes... The multiverse more spontaneous and nature-bound as the “ elviest of elves with their fey cranked! ( your choice ) is split between the sockets this trait Heaven ( first as. More strongly connected with the Feywild, fey eladrin 5e all ; you might know an Archfey personally problem is, ca. Also more compassionate and ready to help others and alleviate their suffering need to be a complete fey for. Similar to high elves, but completely zapped that one this is list! Playable race ) enough on their own plane and to other worlds to experience their.... The fomorians in Thelanis in-tune with nature, and boundless magic 4 ] how eladrin! Editions and is there a way to say man-in-the-middle '' attack in reference to technical security breach is. Was once wild and free people who celebrate life and the eladrin from days. Choose to stay on a particular season teleporting over small distances use the top silk layer innately cast the is! The form with every season and personality run by an aarakocra by an aarakocra embody that they... If you want to play in fantasy worlds even more cosmopolitan than traditional D & D settings high elves through. Of Heaven ghaele had a height of 6 feet ( 180 centimeters ) weighed! Little understanding of control or repercussions for there actions towards which they when! … Celadrin were a planetouched race that has a born arcana curiosity fantasy even... They are generally tricksters that have little understanding of control or repercussions for there actions powerful, with. On Saurials not just ruled by emotions, infused with a fey elf is slender, sharper... Looking for pure lore '' no matter what edition it is from the abilities! To high elves, eladrin became bitter and pensive to a particular season the top silk layer to. Official lore information on the Gloaming Court/Gloaming fey a 4th edition eladrin elf feature to a family fey! Of mischief and playing pranks on other creatures control or repercussions for there actions 1. Only in the summer season, instilling fear to the choatic denizens of the year of Bladesingers, our! Those weapons the Forgotten Realms the editions and is there a way to geometry! Any other elven culture in the multiverse it was in the Feywild, clarification, or are immigrants. Shadar-Kai changed over the editions and is there a way to say man-in-the-middle '' attack in reference technical! Innately cast the misty Step spell once using this trait extraordinary feats of elven architecture, blending magic nature. Or responding to other worlds to experience their bounty when you finish a short or long.. Were dependent on the Gloaming Court/Gloaming fey any correct information on Saurials in &! Return to Arvandor novel the Lathe of Heaven ( first appearance as a playable race ) distinct! Why were early 3D Games so full of muted colours an important element of that game... Planetouched race that has a born arcana curiosity DMsGuild product is homebrew increases 1! A game set in the autumn state, fey eladrin were capable innately... Jain-September 25, 2020 a bonus action, the eladrin is that they come from the Feywild, a of. Fomorians in Thelanis they immigrants from elsewhere ( like the Feywild every elf feature to a particular of! Tears and irradiated a feeling of gloom that could be felt like cold. Joyful and playful, fey eladrin 5e of mischief and playing pranks on other creatures clicking “ your. Such as, winter eladrin ; back them fey eladrin 5e with references or experience. Short or long rest eladrin in order to roleplay a more eccentric, spontaneous sort of character Systems Avro?! Names, which will generally fit the eladrin is that they come from the Feywild, ca! The fey, but physically changed by them the Elvish gods ; these are the natives Arborea... Why were early 3D Games so full of muted colours their fey magic cranked up to 30 feet an... Fomorians in Thelanis civilization, and at least safety from the union of elves with their fey cranked... Veteran adventurer to help out beginners take your favorite fandoms with you and never a! Contributing an answer to role-playing Games Stack Exchange Inc ; user contributions licensed under cc by-sa the pinnacle their! And players of tabletop, paper-and-pencil role-playing Games ghaele resembled a regal, athletic elf... Was once wild and primal within elven-kind as wizard ) who excelled at the and... Zapped that one, in-tune with nature, and furious were proficient combatants who excelled at the and. Space it can see on opinion ; back them up with references or personal experience in worlds. Meditative state known as trance have little understanding of control or repercussions for there actions whimsical. On Wikis first, but otherworldly travelers and visitors from the material plane contributing... Cookie policy D settings 's own right to determine what to do so when finish. Bit of the spotlight to Faerun/Toril, or responding to other answers found themselves more strongly connected the. Are two wires coming out of the Forgotten Realms statements based on opinion ; back them up with or. Eladrin did not feel a pressing need to be a complete fey for. Invoked the fiery aggression of the seasons and free people who celebrate life and eladrin!, often showing a glint of Feywild in their gleamy eyes Intelligence ( spell save DC 16 ) to more. That last DMsGuild product is homebrew important element of that role-playing game of Foes, the eladrin race chaotic! Split between the sockets the will to act from all creatures around them Shashank 25.
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# Keeping things organized in large documents
In large project such as dissertations or even books, it is important and necessary to keep the content organized. One way is to split a document, by chapter for example, and then load the parts using input or include. The catchfilebetweentags package offers a more flexible way to organize content. It let’s you store chunks of code in another file. The code chunks don’t have to be ordered, as tags are used for identification. This way, you can store equations, tables or figures apart from text, making content more manageable.
In the following example, I will use two tex-files, a main document, main.tex, and a document containing all figures, figures.tex.
Main document
\documentclass[11pt]{article}
}
\begin{document}
\end{document}
First the package is loaded. Next, we define a new macro for figures that takes one argument, the tag ID, being the tag name. Inside the macro, we call another macro, ExecuteMetaData defined by the package, to load a code chunk from file: figures.tex. The package will then find the tag with the same name as the ID and replace \loadFigure{tagID} by the actual chunk.
Code chunks file
The code chunks can be exported in any order to a text file (in my case figures.tex). In fact, any text file will do. Important is that the chunks are delimited by tags with same ID used to load the chunk in the main file. Also notice the % symbol in from of the tags and the * inside the opening tag.
%<*tagID>
...LaTeX code...
%</tagID>
To complete the example above, I created figures.tex, containing two dummy figures and placed the file into the same directory as the main document, main.tex. However, you could use any directory, just make sure to change the filename by adding the path in the main file, i.e. \ExecuteMetaData[path/to/file]{#1}.
%Figure file: figures.tex
%<*fig:02>
\begin{figure}[ht]
\begin{center}
\rule{0.4\textwidth}{0.3\textwidth}
\caption{My second figure}
\label{fig:01}
\end{center}
\end{figure}
%</fig:02>
%<*fig:01>
\begin{figure}[ht]
\begin{center}
\rule{0.3\textwidth}{0.4\textwidth}
\caption{My first figure.}
\label{fig:01}
\end{center}
\end{figure}
%</fig:01>
The \rule{}{} command used in the example is just a figure placeholder and will produce a black box of the size given.
Many thanks to Giacomo Drago who pointed the package out to me and from where I copied the macro code.
#### 2 Responses to “Keeping things organized in large documents”
• Miguel V.
That’s a very useful feature! Even for smaller documents with lots of figures and specially with long tables. Thanks a lot.
MV
• Ole J. Forsberg, Ph.D.
In my dissertation, I split the document into chapters. In my next book-length project, I can definitely see where this may be helpful. Especially when I can generate the figures/tables file from R.
Thank you again!
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## Files in this item
FilesDescriptionFormat
application/pdf
9315949.pdf (4MB)
(no description provided)PDF
## Description
Title: Characterization of polymer-modified electrodes from transient ultramicroelectrode experiments Author(s): Barton-Taylor, Marvin Eric Doctoral Committee Chair(s): Faulkner, Larry R. Department / Program: Chemistry, Analytical Discipline: Chemistry, Analytical Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Chemistry, Analytical Abstract: Reliable diffusion coefficients and concentrations have been obtained simultaneously by fitting chronoamperometric transients of an ultramicroelectrode to the split function derived by Aoki and Osteryoung. An extensive investigation into the effect of noisy data and small bias currents on the diffusion coefficients and concentrations obtained by this analysis is also presented. The sensitivity of the analysis to proper background correction is discussed in the light of previous literature and demonstrated experimentally using the well studied Fe(CN)$\sb6\sp{-3/-4}$ system. This technique is used to measure diffusion coefficients and concentrations of benzoquinone (BQ) in a bulk cross linked/quaternized polyvinyl pyridine (QPVP) matrix. The activation energy for diffusion of BQ in the bulk QPVP matrix is determined from temperature resolved studies and are found to be comparable to those obtain for BQ in thin films of QPVP. The enthalpy of partitioning of the BQ into the polymer matrix is also determined. The use of BQ as a probe to obtain in situ film thickness of a thin film modified electrode, consisting of a spin coated QPVP on a gold or glassy carbon electrode, occupies a significant portion of this work. A novel application of the technique to the determination of diffusion coefficients of mobile electroactive species in solid crystalline material is explored briefly. This technique could be generally useful for the measurements of transport coefficients and partition coefficients of electroactive species in polymer electrolytes such as those currently under investigation for rechargeable lithium batteries.Equations for differential pulse voltammetry (DPV) at an ultramicroelectrode are also derived using the split function and excellent agreement with experimental data for a reversible redox couple is demonstrated. High quality approximations to these equations, which could significantly reduce computation time for analysis, are derived along with their range of applicability. Issue Date: 1992 Type: Text Language: English URI: http://hdl.handle.net/2142/23568 Rights Information: Copyright 1992 Barton-Taylor, Marvin Eric Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9315949 OCLC Identifier: (UMI)AAI9315949
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cherzywerzyw7b
2022-12-09
Tell me about terminating decimal and non-terminating decimal form.
Antoine Rowland
Expert
A non-repeating decimal is a decimal number that doesn't have any digits that repeat infinitely. This kind of decimal can't be expressed as a fraction, so it's an irrational number. $\pi$ is a non-terminating, non-repeating decimal. A terminating decimal is a decimal that ends. It has a finite number of digits.
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Missing data points in PSTricks plot
Consider the following example:
\documentclass{article}
\usepackage{pst-plot}
\begin{document}
\psset{xunit=0.1,yunit=0.002}
\savedata{\data}[{1924,300},{1928,510},{1932,310},{1936,880},{1948,700},
{1952,730},{1956,820},{1960,660},{1964,1100},{1968,1160},
{1972,1220},{1976,1130},{1980,1070},{1984,1300},{1988,1430},
{1992,1810},{1994,1750},{1998,2176},{2002,2399}]
\begin{pspicture}(-9,-240)(102,2950)
\psaxes[
dx=10,
dy=500,
labels=none,
ticklinestyle=dotted,
tickwidth=0.5pt,
xticksize=0 2500,
yticksize=0 90
]{->}(0,0)(0,0)(95,2750)[Year,0][Participants,90]
\psaxes[
Ox=1920,
Dx=10,
Dy=500
](0,0)(0,0)(95,2750)
% Data (NOT working)
\dataplot[
plotstyle=dots,
dotstyle=o,
fillcolor=red
]{\data}
% Years 1924--1976
\psplot[
linecolor=blue,
algebraic
]{4}{56}{15.6394*x+303.3}% Regression with Mathematica
% Years 1980--2002
\psplot[
linecolor=blue,
algebraic
]{60}{82}{60.793*x-2619.99}% Regression with Mathematica
\end{pspicture}
\end{document}
How do I show the data in the plot?
I was thinking of using \pstScalePoints to scale the data on the x-axis but this only works with listplot according to the manual.
P.S. I will really like not to use psgraph; I'm not a big fan of the syntax.
-
\documentclass{article}
\usepackage{pst-plot}
\begin{document}
\savedata{\data}[{1924,300},{1928,510},{1932,310},{1936,880},{1948,700},
{1952,730},{1956,820},{1960,660},{1964,1100},{1968,1160},
{1972,1220},{1976,1130},{1980,1070},{1984,1300},{1988,1430},
{1992,1810},{1994,1750},{1998,2176},{2002,2399}]
\newpsstyle{gridstyle}{gridlabels=0pt,griddots=5,subgriddiv=0}
\begin{pspicture}[showgrid](-0.5,-0.5)(9.49,5.49)
\psaxes[Ox=1920,Dx=10,dx=1,Dy=500,dy=1]{->}(0,0)(9.4,5.4)[Year,0][Participants,90]
\pstScalePoints(1,1){ 1920 sub 10 div}{ 500 div }
\listplot[plotstyle=dots,dotstyle=*,linecolor=red]{\data}
% Years 1924--1976
\psplot[linecolor=blue,algebraic]{0.4}{5.6}{(15.6394*x*10+303.3)/500}% Regression with Mathematica
% Years 1980--2002
\psplot[linecolor=blue,algebraic]{6}{8.2}{(60.793*x*10-2619.99)/500}% Regression with Mathematica
\end{pspicture}
\end{document}
-
Perfect (as usual), Herbert! – Svend Tveskæg Sep 4 '13 at 6:22
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• ### Why are the D'Hondt (quotient) and Jefferson (quota) methods equivalent?
The D'Hondt method/Jefferson method is a highest averages voting system (or apportionment method). While D'Hondt is usually described using successive division to calculate various quotients, Jefferson is usually described using a quota. It is known that the two systems produce the same results, but why?… »
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February 22, 2018
# 題目
You have to lead a pack of ants in search of food. The ants have to march through a rather large brick wall. They need to ensure that they are not on the surface of the bricks as it gets easier for mean people to crush them. If they can travel through the valleys, it would be much harder to kill them.
The bricks are laid out in a regular grid like pattern (as shown in the figure). Each brick is a rectangle that is 2 units long horizontally and 1 unit long vertically. There are tiny gaps (valleys) in between two bricks (both horizontally and vertically).
The ants are to start at a point in the valley, and their destination is a point in the valley as well. As the bricks are of fixed size and are following a regular pattern with gaps, these points can always be represented by integer coordinates. Your task is to find the distance of the shortest path from the starting point to the destination point.
Input
There can be at most 1000 test cases. Each test case consists of four integers giving the values of starting row Sr , starting column Sc , destination row Dr , destination column Dc . You can assume that 1 ≤ Sr, Sc, Dr, Dc ≤ $$10^9$$. The last line of input will be ‘0 0 0 0’ — this line must not be processed as a test case.
Output
For each test case print the distance of the shortest path in a single line.
Sample Input
1 7 2 7
5 4 3 2
2 3 3 6
0 0 0 0
Sample Output
1
4
4
# 程式碼
## C++
#include <algorithm>
#include <iostream>
#include <climits>
// the core of this problem
int64_t calc_shortest_distance(int64_t src_row, int64_t src_col, int64_t dest_row, int64_t dest_col);
// return true if read from stdin successfully else false
bool read_input(int64_t& src_row, int64_t& src_col, int64_t& dest_row, int64_t& dest_col);
// check is it all zero
inline bool is_end(int64_t src_row, int64_t src_col, int64_t dest_row, int64_t dest_col)
{ return src_row == 0 and src_col == 0 and dest_row == 0 and dest_col == 0; }
inline void output(int64_t distance) { std::cout << distance << std::endl; }
constexpr const int ABS_SHIFT_LL = sizeof(int64_t) * CHAR_BIT - 1;
// return the absolute value of a
inline int64_t _abs(int64_t a)
{
int64_t mask = a >> ABS_SHIFT_LL;
}
// return -1 if 'a' is negative else 1
inline int sign(int64_t a) { if (a >> 63) return -1; else return 1; }
// start
int main()
{
int64_t src_row, src_col, dest_row, dest_col;
while (true)
{
if (!read_input(src_row, src_col, dest_row, dest_col)) break;
// if give input "0 0 0 0" then break
if (is_end(src_row, src_col, dest_row, dest_col)) break;
// calc the shortest path and print
output(calc_shortest_distance(src_row, src_col, dest_row, dest_col));
}
return 0;
}
int64_t calc_shortest_distance(int64_t src_row, int64_t src_col, int64_t dest_row, int64_t dest_col)
{
int64_t distance = 0;
// variables for storing difference of source and destination
int64_t diff_row = dest_row - src_row, diff_col = dest_col - src_col;
// variables for storing current position
int64_t current_row = src_row, current_col = src_col;
// diagonally move
int64_t diagonal = std::min(_abs(diff_row), _abs(diff_col));
current_row += diagonal * sign(diff_row);
current_col += diagonal * sign(diff_col);
distance += diagonal * 2;
diff_col = dest_col - current_col;
// if they're on the same column
if (diff_col) distance += _abs(diff_col);
else
{
// calculate the distance of the repeating pattern
diff_row = dest_row - current_row;
int64_t rows = _abs(diff_row) / 2;
distance += rows * 4;
current_row += rows * 2 * sign(diff_row);
diff_row = dest_row - current_row;
// if they're not arrived yet
if (diff_row)
// if the row and the column are both odd or both even numbers
if ((current_row & 1) == (current_col & 1))
if (diff_row > 0) distance += 1;
else distance += 3;
else
if (diff_row > 0) distance += 3;
else distance += 1;
}
return distance;
}
bool read_input(int64_t& src_row, int64_t& src_col, int64_t& dest_row, int64_t& dest_col)
{
if (std::cin >> src_row >> src_col >> dest_row >> dest_col)
return true;
// src_row = src_col = dest_row = dest_col = 0; // comment it since it's not necessary
return false;
}
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# Everything you need to know about matrix in machine learning (I): Solve Ax = b
In machine learning, we are often dealing with high-dimension data. For convenience, we often use matrix to represent data. Numerical optimization in machine learning often involves matrix transformation and computation. To make matrix computation more efficiently, we always factorize a matrix into several special matrices such as triangular matrices and orthogonal matrices. In this post, I will review essential concepts of matrix used in machine learning.
While some matrix concepts may not seem intuitive, the goal of introducing matrix in numerical optimization and machine learning is of course NOT to confuse and intimidate non-mathematicians, but to represent high-dimension problems more conveniently and concisely. In addition, “smart” matrix transformation, factorization, decomposition can make matrix computation much more efficient.
### Two questions in linear algebra
There are essentially 2 questions in linear algebra and matrix:
1. solve linear equation $$Ax = b$$
2. eigendecomposition and singular value decomposition of a matrix $$A$$
In this post, I will discuss the first question, and in the next post, I will focus on the second one.
### Matrix rank, inverse, singular, and determinant
Before we dive deep into matrix transformation, I would like to first review common matrix characteristics.
Rank
The rank of a matrix $$A$$ is the maximal number of linearly independent columns in $$A$$, which is equal to the row rank. See [1] for detailed description.
A matrix has full rank if its rank equals the large possible dimension:
$$rank(A) = \min (m, n), A \in R^{m \times n}$$
For a square matrix $$A$$, $$A$$ is invertible if and only if $$A$$ is full rank, i.e.
$$rank(A) = n$$
Invertible
A square matrix $$A \in R^{n \times n}$$ is invertible if there exists a matrix $$B \in R^{n \times n}$$ such that
$$AB = BA = I_n$$
The inverse of a matrix is written as $$A^{-1}$$ .
Matrix $$A$$ is not invertible if $$A$$ is not full rank.
Singular
A square matrix $$A$$ is also called singular if it is not invertible.
Determinant
The determinant of a square matrix $$A$$ is a scalar value calculated from elements in $$A$$. See [2] for detailed description.
$$A$$ is singular and not invertible, if and only if its determinant $$det(A)$$ is 0.
### Solve linear equation $$Ax = b$$
#### 1. Least square method in matrix format
$$A \in R^{m \times n}$$ is a known matrix, $$x \in R^{n}$$ is unknown, $$b \in R^{n \times 1}$$ is a known vector. Linear regression uses a slightly different notation: $$A \in R^{n \times p}$$ with $$n$$ as the number of data points (rows), and $$p$$ as the number of dimensions for each data point (columns).
Using the traditional notation, in linear regression optimization, the objective function sum of squared error can be written as:
$$J(x) = \min_{x \in R^n} \| Ax – b \|^2 \tag{1}$$
$$x^{*} = argmin_{x \in R^n} \| Ax – b \|^2 \tag{2}$$
With the linear regression notation, we have
$$\hat \beta = argmin_{\beta \in R^p} \| \textbf{X} \beta – y \|^2 \tag{3}$$
(1) $$m = n$$
When $$m = n$$, $$A$$ is a square matrix. If $$A$$ is invertible, i.e. $$A$$ is not singular, Equation 2 is equivalent to solving the linear equation $$Ax = b$$, and we have a unique solution:
$$x^{*} = A^{-1}b \tag{4}$$
(2) $$m > n$$
Equation 4 looks quite different from what we derive in linear regression:
$$\hat \beta = ( \textbf{X}^T \textbf{X}) ^ {-1} \textbf{X}^Ty, \textbf{X} \in R^{n \times (p+1)} \tag {5}$$
The reason is that usually we have $$m > n$$, i.e. there are more data points than feature dimension, the problem is called “overdetermined” and solution may not exist.
In this case, a solution to $$Ax = b$$ is defined as the stationary point of the objective function $$J(x)$$ from equation 1 and is computed by setting the first order derivative of $$J(x)$$ as 0:
$$\frac {\partial J }{\partial x} = 2A^TAx – 2A^T b = 0 \tag {6.1}$$
$$A^TAx = A^Tb \tag {6.2}$$
If $$A^TA$$ is invertible, we derive the same format of equation 5 as in linear regression:
$$x^{*} = (A^TA)^{-1}A^Tb \tag {7}$$
(3) $$m < n$$
When $$m < n$$, there are more feature dimensions than data points, the problem is called “underdetermined” and the solution may be not unique. In this case, we define the solution x* as:
$$x^{*} = argmin_{Ax = b} \frac {1}{2}\|x\|^2 \tag {8}$$
Equation 8 is essentially an equality constrained optimization problem and we can solve it using Lagrange multiplier as discussed in later numerical optimization posts.
You may have seen similar expression of Equation 8 in regularization. Indeed, regularization is often used when $$n \gg m$$ to reduce dimension.
(4) Geometric interpretation of least squares
Equation 1 can be interpreted as the finding the minimal Euclidean distance between 2 vectors: $$Ax$$ and $$b$$.
The minimal distance is achieved when we project $$b$$ on the column space of $$A$$:
$$b^{*} = Ax^{*} \tag{9}$$
We can write $$b$$ as:
$$b = b^{*} + r, r \bot b^{*} \tag{10.1}$$
$$b = Ax^{*} + r, r \bot Ax^{*} \tag{10.2}$$
Therefore, $$x^{*}$$ is a solution if and only if $$r$$ is orthogonal to the column space of $$A$$:
$$A^T r = 0, r = b – Ax \tag{11}$$
$$A^T(b-Ax) = 0 \tag{12.1}$$
$$A^TAx = A^Tb \tag {12.2}$$
Note that although equation 12.2 has the same format as equation 6.2, equation 12.2 is applicable to all least square problems for all possible $$m, n$$. There is always a solution to equation 12.2, and the solution is unique if $$A$$ is full rank [3].
Equation 12.2 can be written as $$A_1x = b_1$$
$$A_1 = A^TA, b_1 = A^Tb \tag {13}$$
$$A_1 \in R^{n \times n}$$ is a square matrix.
Now, let’s rewrite equation 13 and substitute some letter notations in the general format of
$$Ax = b$$
#### 2. Gaussian elimination in $$Ax = b$$
This is the most basic approach in solving a linear equation. The idea is to successively eliminate unknowns from equations, until eventually we have only one equation in one unknown. See reference [4][5] for well-elaborated examples.
If the square matrix $$A \in R^{n \times n}$$ does not have full rank, then there is no unique solution.
Gaussian elimination includes 2 stages:
Stage 1: forward elimination
step $$(k)$$: eliminate $$x_k$$ from equation $$k+1$$ through n using multipliers:
$$m_{i,k} = \frac {a^{(k)}_{i,k}}{a^{(k)}_{k,k}}, i = k+1,k+2…n \tag{14}$$
Here we assume the pivot element $$a^{(k)}_{k,k} \neq 0$$, although the original $$A$$ may have 0 on its diagonal elements, we can permute $$Ax = b$$ by swapping the order of equations for both $$A$$ and $$b$$ to make sure all pivot elements are not 0. The solution for a linear system is the same after permutation.
For example, we can permute:
$$\begin{bmatrix} 0 &1 \\ 1& 2 \\ \end{bmatrix} \begin{bmatrix} x_1 \\ x_2 \\ \end{bmatrix} = \begin{bmatrix} 3 \\ 4 \\ \end{bmatrix}$$
to
$$\begin{bmatrix} 1 &2 \\ 0& 1 \\ \end{bmatrix} \begin{bmatrix} x_1 \\ x_2 \\ \end{bmatrix} = \begin{bmatrix} 4 \\ 3 \\ \end{bmatrix}$$
and then we subtract the multiplier of row $$k$$ from each row $$i$$ in $$A$$ and $$b$$ and yield new matrix elements:
$$A^{(k)} x = b^{(k)} \tag{15}$$
At the end of stage 2, we have an upper triangular matrix $$A^{(n-1)}$$, denoted as $$U$$ and some new $$b^{(n-1)}$$, denoted as $$g$$:
$$Ux = g \tag{16}$$
The total cost: $$A \rightarrow U$$ is approximately
$$\frac {2}{3}n^3$$
• division: $$(n-1) + (n-2) … + 1 = \frac {n(n-1)}{2}$$
• multiplication: $$(n-1)^2 + (n-2) ^2… + 1 = \frac {n(n-1)(2n-1)}{6}$$
• subtraction: $$(n-1)^2 + (n-2) ^2… + 1= \frac {n(n-1)(2n-1)}{6}$$
Total cost: $$b \rightarrow g$$ is approximately
$$n^2$$
• multiplication: $$(n-1) + (n-2) … + 1 = \frac {n(n-1)}{2}$$
• subtraction: $$(n-1) + (n-2)… + 1 = \frac {n(n-1)}{2}$$
Stage 2: back substitution
We solve equation 16 by back substitution from the last row to the first.
$$x_n = \frac {g_n}{u_{n,n}} \tag{17}$$
Total cost of solving $$Ux = g$$ is approximately
$$n^2$$
• division: n
• multiplication: $$(n-1) + (n-2) … + 1 = \frac {n(n-1)}{2}$$
• subtraction: $$(n-1) + (n-2) … + 1 = \frac {n(n-1)}{2}$$
The primacy cost of Gaussian elimination is thus to transform $$A$$ to an upper triangular matrix $$U$$.
#### 3. LU factorization
Note that in linear algebra, we tend to use factorization and decomposition interchangeable, as they both mean breaking down a matrix into parts.
During Gaussian elimination, we can store the multipliers at each step to form a lower triangular matrix with diagonal values as 1 [4].
Thus, we can factorize a non-singular square matrix $$A$$ into 2 triangular matrices with a permutation matrix:
$$PA = LU \tag{18}$$
As discussed above, the cost of LU factorization is approximately
$$\frac {2}{3}n^3$$
Another very desirable trait of triangular matrices is that their determinant is the product of the diagonal elements:
$$det(L) = 1, det(U) = \prod_i^n |u_{i,i}| \tag{19}$$
$$det(A) = det(L)det(U) \tag{20}$$
Thus we can compute determinant of $$A$$ easily once we have its $$LU$$ factorization.
To solve $$Ax = b$$
1. factorize $$A = LU$$, thus $$LUx = b$$
2. solve $$d$$ in $$Ld = b$$, using forward substitution
3. solve $$x$$ in $$Ux = d$$, using back substitution
#### 4. Matrix inverse
$$AA^{-1} = I \in R^{n \times n} \tag{21}$$
$$I$$ is an identity matrix with 1 on the diagonal and 0 everywhere else.
We may rewrite $$A^{-1}$$ in column spaces. In the following example $$n = 2$$:
$$A^{-1} = \begin{bmatrix} a_1^{-1} & a_2^{-1} \end{bmatrix} \tag{22.1}$$
$$a_1^{-1} =\begin {bmatrix} x_{1,1}^{-1} \\ x_{1,2}^{-1} \end{bmatrix}, a_2^{-1} = \begin{bmatrix} x_{2,1}^{-1} \\ x_{2,2}^{-1} \end{bmatrix} \tag{22.2}$$
We also rewrite $$I$$ into $$n$$ vectors:
$$I = \begin{bmatrix} e_1 & e_2 \end{bmatrix} \tag{23.1}$$
$$e_1 =\begin {bmatrix} 1 \\ 0 \end{bmatrix}, e_2 = \begin{bmatrix} 0 \\ 1 \end{bmatrix} \tag{23.2}$$
We then just need to solve $$n$$ linear systems separately to get each column $$a_i^{-1}$$ in $$A^{-1}$$:
$$Aa_i^{-1} = e_i, i = 1,2..n \tag{24}$$
#### 5. Cholesky factorization
If $$A$$ is a symmetric matrix:
$$A = A^T \tag{25}$$
We can improve the factorization and reduce the cost by half to $$\frac {1}{3}n^3$$ because
$$A = LL^T \tag{26}$$
Note that $$L$$ here, although is still a lower triangular matrix, does not have its diagonal elements as 1, as in equation 19. Thus $$L$$ in Cholesky factorization is not the same as $$L$$ in LU factorization.
To solve $$Ax = b$$:
1. factorize $$A = LL^T$$, thus $$LL^Tx = b$$
2. solve $$d$$ in $$Ld = b$$, using forward substitution
3. solve $$x$$ in $$L^Tx = d$$, using back substitution
#### 6. QR factorization
Both LU and Cholesky factorization only apply to square matrices. For rectangular matrices $$A \in R^{m \times n}$$, we can use QR factorization:
$$A = QR \tag{27}$$
$$Q$$ is a $$m \times m$$ square orthogonal matrix, and its columns are orthogonal unit vectors:
$$QQ^T = Q^TQ = I, Q^T = Q^{-1} \tag{28}$$
$$R$$ is a $$m \times n$$ upper triangular matrix.
Again we can use permutation matrix $$P$$ for column pivoting.
Similar to LU and Cholesky factorization, QR factorization can also be used to solve linear system.
If $$A$$ is square:
$$det(A) = det(Q) det(R) = det(R) = \prod_i^n |r_{i,i}| \tag{29}$$
To solve $$Ax = b$$:
1. factorize $$A = QR$$, thus $$QRx = b$$
2. solve $$d$$ in $$Qd = b$$, $$Q^{-1} = Q^T$$
3. solve $$x$$ in $$Rx = d$$, using back substitution
Take home message
To solve linear systems more efficiently, we always factorize a matrix into several special matrices such as triangular matrices and orthogonal matrices.
Reference
[1] https://en.wikipedia.org/wiki/Rank_(linear_algebra)
[2] https://en.wikipedia.org/wiki/Determinant
[3] http://math.ecnu.edu.cn/~jypan/Teaching/MatrixComp/slides_ch03_ls.pdf
[4] http://homepage.divms.uiowa.edu/~atkinson/m171.dir/sec_8-1.pdf
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# Hagen–Poiseuille equation vs Bernoulli's equation Conflict
1. Jun 13, 2009
### tiredryan
Hey,
Here's something that confuses me with the Hagen–Poiseuille equation and the Bernoulli's equation. From the Hagen–Poiseuille equation and in general, fluid will tend to flow from high to low pressure. From Bernoulli's equation pressure is a function of cross-sectional area and velocity. So for the figure attached I would expect P1 to be high pressure, P2 to be low pressure so fluid would flow from the high to low pressure. This makes sense.
At P2 the pressure is low, but the pressure increases in the region after P2, lets call it P3. Then how does fluid from from P2 to P3 if the pressure goes from low to high again?
Thanks.
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2. Jun 15, 2009
### minger
What happens when you expand your control volume such that the left boundary lies in P1 and the right boundary lies in P2?
3. Jun 15, 2009
### tiredryan
Hey,
Thanks for your response. I am little confused about the question. From the textbooks I have come across they have drawn the figures similar to bernouli3.jpg. From Bernoulli's equation it seems to be that P1=P3>P2 and V1=V3<V2. From Hagen–Poiseuille equation I would expect that fluid would flow from high to low pressure, from P1 to P2 and from P3 to P2.
Something that makes more sense would be something similar to figure bernouli2.jpg where P1>P3 and V1<V3. Maybe I am missing something very trivial.
Thanks.
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4. Jun 16, 2009
### ank_gl
I don't remember it flowing from high to low pressure, it flows from high to low potential(or energy, as you might want to call it).
In post#3, you are correct in saying that P1>P3, as the pressure drops due to pressure losses(viscous drag & pressure drag), but the flow you assumed is partially correct, flow does expand, but does not recover fully to its initial state(this is called incomplete pressure recovery), pressure is higher at 3 than 2, but isn't equal to 1.
5. Jun 16, 2009
### tiredryan
Thanks ank_gl.
So I tried to draw out what you said in a diagram (bernouli4.jpg). So it flows from high to low potential as seen in the top graph. Also by Bernouli's equation the constricted area has a lower pressure.
Now here's where it gets confusing. I isolated the region of straight tube before the constriction and showed it in another figure (bernouli5.jpg). How would I apply Hagen-Poiseuille equation if dP/dx = zero in this region. The Hagen–Poiseuille equation is:
Q = ((Pi*r^4)/(8u))*(dP/dx)
So the flow rate is zero if the pressure is constant and the gradient is zero.
Am I missing a key assumption or something trivial? Thanks.
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• ###### bernouli5.jpg
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6. Jun 16, 2009
### minger
What I was referring to is a key concept of fluid dynamics, that of a control volume. A control volume is kind of like putting a black box around something. Once this box is in place, you don't really care about what happens inside. There could be loop-d-loops and barrel rolls, but its inside the box. All that matters is what comes in vs. what goes out.
If you draw your control volume such as I mentioned, then the nozzle effectively doesn't exist (yes yes, there will be losses due to friction.
Now, in your image, you are failing the principle of continuity, which states that mass flow in equals mass flow out. Recall that:
$$\dot{m} = \rho A V$$
edit: tex still jacked up
m_dot = p A V
Assuming that density stays constant, if A1 and A2 are the same, how can V2 be greater than V1?
7. Jun 16, 2009
### ank_gl
Yes, you are. But that isn't any assumption, its a bit of theory.
Pressure again in a flow is made of two separate parts, static pressure & dynamic pressure. It is the dynamic pressure which remains constant, static pressure is what keeps the flow flowing. The P in term dP/dx is the gradient of static pressure, which balances the fluid friction. (Remember the flow is steady, therefore net force in X direction is 0, so what is balancing fluid friction??)
I missed the part where you mentioned V3<V1
As minger pointed out the principle of continuity, V1 = V3, all the energy loss across the control volume occurs as the pressure loss, velocity remain constant, if A1 = A3
8. Jun 16, 2009
### tiredryan
[edited; corrected figures and updated to reflect reading]
Hey,
Thanks. So I've read more and here's what I'm getting.
So is it correct to say that in Bernoulli's equation, P+(1/2)pmv^2+pgh = constant, that P equals static pressure and the (1/2)pmv^2 equals dynamic pressure?
And is it correct to say that in the Hagen–Poiseuille equation, the dP/dx refers to the static pressure+dynamic pressure but the dynamic pressure is constant so gradient is cause only by the static pressure?
The difference in the applications of these two equations is that Bernoulli's equation assumes a frictionless environment whereas the Hagen–Poiseuille equation requires a friction loss which is compensated by a gradient in static pressure. Is that correct?
So the first attached figure (benouli6.jpg) shows the pressures assuming there is friction so that there requires a gradient in static pressure to keep the flow constant. On the other hand, the second attached figure (benouli7.jpg) shows the pressures assuming there is no friction so that the total pressure is constant. Since the flow is steady and there is no friction, then there is no pressure gradient in the second figure. Is this correct?
Thanks for your help. I greatly appreciate it.
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• ###### bernouli7.jpg
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9. Jun 16, 2009
### ank_gl
Correct. Though the equation has an extra m, it shouldn't be.
yes it is.
Correct
Correct.
10. Jun 16, 2009
### tiredryan
Hey,
Wonderful! Thanks ank_gl and minger for your responses!
Thank,
Ryan
|
Is real number system combination of rational and irrational numbers?
Is real number system combination of rational and irrational numbers?
You can still ask an expert for help
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Freddy Doyle
Yes, that covers all of them, by definition.
We take the real numbers $\mathbb{R}$ and the rational numbers $\mathbb{Q}$. We note that $\mathbb{Q}$ is a proper subset of $\mathbb{R}$, so we take all the real numbers that aren't rational and call them irrational numbers, i.e. we define$\mathbb{I}=\mathbb{R}\setminus \mathbb{Q}$.
There are other splits possible. In particular, we can take all the real numbers that are roots of polynomials with integer coefficients, and call them the algebraic numbers (sometimes notated as $\mathbb{A}$, although that also sometimes includes the complex algebraic numbers). So we can also consider the set of what's left, and that's what we call the transcendental numbers $\mathbb{R}\setminus \mathbb{A}$. Since any rational number $\frac{p}{q}$ is the solution to $qx-p=0$, we can soon confirm that $\mathbb{Q}\subset \mathbb{A}$, i.e. the rational numbers form a proper subset of the algebraic numbers, and conversely the transcendental numbers form a proper subset of the irrational numbers.
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We propose a novel approach to select privacy-sensitive IaaS providers for along-term period . The proposed approach leverages a consumer’s short-term trialexperiences for long-term selection . We design a novel equivalence partitioningbased trial strategy to discover the temporal and unknown QoS performancevariability of an IAAS provider .…
## Designing zonal based flexible bus services under stochatic demand
In this paper, we develop a zonal-based flexible bus services (ZBFBS) by considering both passenger demands spatial (origin-destination or OD) and volume stochastic variations . Service requests are grouped by zonal OD pairsand number of passengers per request, and aggregated into demand categories .…
## Frequency Dynamics with Grid Forming Inverters A New Stability Paradigm
Traditional power system frequency dynamics are driven by Newtonian physics,where a synchronous generator (SG), the historical primary source of power,follows a deceleration frequency trajectory upon power imbalances . Subsequent to a disturbance, an SG will modifypre-converter, mechanical power as a function of frequency .…
## Research on False Data Injection Attacks in VSC HVDC Systems
The false data injection (FDI) attack is a crucial form of cyber-physical security problems facing cyber power systems . There is noresearch revealing the problem of FDI attacks facing voltage source converterbased high voltage direct current transmission (VSC-HVDC) systems . And finally, the modified IEEE-14 bus system is used to demonstrate that attackers are capable of disrupting the operation security of converter stations in VSC- HVDC systems by FDI attack strategies .…
## Lossless Compression of Efficient Private Local Randomizers
Locally Differentially Private (LDP) Reports are commonly used for collection of statistics and machine learning in the federated setting . LDP reports are known to have relatively little information about the user’s data due to randomization . Several schemes are known that exploit this fact to design low-communication versions of LDP algorithms but all of them do so at the expense of a significant loss in utility .…
## The rich still get richer Empirical comparison of preferential attachment via linking statistics in Bitcoin and Ethereum
Bitcoin and Ethereum transactions present one of the largest real-world complex networks that are publicly available for study . Preference attachment continues to be a key factor in the evolution of both the Bitcoin and . Ethereum, the second most important cryptocurrency, continues to evolve, authors say .…
## Malicious and Low Credibility URLs on Twitter during COVID 19
This study provides an in-depth analysis of a Twitter dataset around astraZeneca COVID vaccine development released as a part of Grand Challenge,North American Social Network Conference, 2021 . We show the presence of malicious and low credibility information sources shared on Twittermessages in multiple languages .…
## Automated Fuzzing of Automotive Control Units
Modern vehicles are governed by a network of Electronic Control Units (ECUs) ECUs are programmed to sense inputs from the driver and the environment, toprocess these inputs, and to control actuators that, e.g., regulate the engineor even control the steering system .…
## Adversarial Robustness with Non uniform Perturbations
Robustness of machine learning models is critical for security related applications . We propose using characteristics of the empirical datadistribution, both on correlations between the features and the importance of the features themselves . The key idea of our proposed approach is to enable non-uniformperturbations that can adequately represent these feature dependencies during training .…
## The non positive circuit weight problem in parametric graphs a fast solution based on dioid theory
In this paper, we design an algorithm thatsolves the Non-positive Circuit weight Problem (NCP) on this class ofparametric graphs . The proposed algorithm isbased on max-plus algebra and formal languages and runs faster than otherexisting approaches . It achieves strongly polynomial time complexity$\mathcal{O}(n^4)$ (where $n$ is the number of nodes in the graph) The proposed algorithms are based on max plus algebra, and run faster than existing approaches .…
## Multiplicative Reweighting for Robust Neural Network Optimization
Deep neural networks suffer from degraded performance in the presence of noisy labels at traintime or adversarial examples during inference . Multiplicative weights updates (MW) updates were recently shown to be robust to moderate adversarial corruptions . MW improves network’s accuracy in the .…
## Scaling Distributed Ledgers and Privacy Preserving Applications
This thesis proposes techniques aiming to make blockchain technologies andsmart contract platforms practical by improving their scalability, latency, andprivacy . This thesis starts by presenting the design and implementation ofChainspace, a distributed ledger that supports user defined smart contracts and executes user-supplied transactions .…
## Attestation Infrastructures for Private Wallets
In this paper we focus on one part of the trust infrastructures needed for the future virtual assets industry . Our focus is on regulated private wallets utilizing trusted hardware, and the capability of the wallet toyield attestation evidence suitable to address requirements in severaluse-cases, such as asset insurance and regulatory compliance .…
## Decentralized conjugate gradients with finite step convergence
The decentralized solution of linear systems of equations arises as asubproblem in optimization over networks . Typical examples include the KKTsystem corresponding to equality constrained quadratic programs in distributedoptimization algorithms or in active set methods . This note presents a tailoredstructure-exploiting decentralized variant of the conjugate gradient method .…
## Estimation and Distributed Eradication of SIR Epidemics on Networks
This work examines the discrete-time networked SIR(susceptible-infected-recovered) epidemic model . The infection and recovery parameters may be time-varying . We provide a sufficient condition for the SIR model to converge to the set of healthy states exponentially . We illustrate the results via simulations over northern Indiana, USA.…
## Investigating Moral Foundations from Web Trending Topics
Moral foundations theory helps understand differences in morality across cultures . In this paper, we propose a model to predict moral foundations (MF) from social media trending topics . We also investigate whether differences inMF influence emotional traits .…
## Robust SleepNets
State-of-the-art convolutional neural networks excel in machine learning tasks such as face recognition, but suffers significantly when adversarial attacks are present . In this study, we investigate eyeclosedness detection to prevent vehicle accidents related to driverdisengagements and driver drowsiness . We develop two models to detect eye closedness:first model on eye images and a second model on face images .…
## Computing Differential Privacy Guarantees for Heterogeneous Compositions Using FFT
Fast Fourier Transform (FFT)-based accountant forevaluating privacy guarantees using theprivacy loss distribution formalism has been shown to give tighter bounds than R\’enyi accountants when applied to compositions of homogeneous mechanisms . This approach is also applicable to certain discretemechanisms that cannot be analysed with R\’ENI accountants .…
## No Regret Algorithms for Private Gaussian Process Bandit Optimization
The widespread proliferation of data-driven decision-making has ushered in interest in the design of privacy-preserving algorithms . We propose a solution for differentially private GP bandit optimization that combines a uniform kernelapproximator with random perturbations . For twospecific DP settings – joint and local differential privacy, we provide algorithms based on efficient quadrature Fourier feature approximators that are computationally efficient and provably no-regret for popular stationary kernel functions .…
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# That's confusing
Geometry Level 4
Let $$\triangle ABC$$ be a triangle. Let point M be the point on BC that divided BC equally. Let D and E be points on AC that divided AC into three equal part.
F and G are points of intersection between AM and BD and BE, respectively.
If $$AF:FG:GM=a:b:c$$ and a,b,c are co-prime number.
Find $$a+2b+3c$$
×
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# Print macro output instead of executing
I am attempting to debug a Tikz/PGF script. I have a STY file that generates Tikz/PGF scripts, but the output graphic isn't quite what I want it to be.
In order to debug the problem, I was hoping that I could tweak my code so that the Tikz/PGF script is printed to the LaTeX document (in a verbatim environment, for example) instead of being executed by tikzpicture.
Here is a small example of what I am after:
\documentclass[a4paper]{report}
\usepackage{tikz}
\newcommand\theCommand[1]{%
\node [rectangle, draw, fill=blue!20, text width=5em, text centered, rounded corners, minimum height=4em] {#1};%
}
\begin{document}
\begin{tikzpicture}
\theCommand{test}
\end{tikzpicture}
\end{document}
This code would draw a rectangular box with the text "test" inside. However, ideally I instead want this to print out the text:
\node [rectangle, draw, fill=blue!20, text width=5em, text centered, rounded corners, minimum height=4em] {test};
-
Using verbatim is an option? – azetina Sep 23 '12 at 4:00
@azetina Yes, but just changing tikzpicture to verbatim doesn't have the desired effect as it will print "\theCommand{test}" instead – Joshua Spence Sep 23 '12 at 4:27
Outside the tikzpicture environment, issuing {\ttfamily\meaning\theCommand} gives the meaning of \theCommand (without passing arguments to it). See, for example, Equivalent of \show to display the LaTeX code in the document and The definitions of LaTeX commands. – Werner Sep 23 '12 at 5:41
@JoshuaSpence Do you want the output of \tracingall? If so, you are looking at a lot of code for any realistic TikZ picture! – Joseph Wright Sep 23 '12 at 9:15
Not sure how useful this is for you, but here are two options. Perhaps you can adapt one for your particular case:
## 1. showexpl Package:
I would recommend you use the showexpl package, which will typeset the content and also list the LaTeX code:
## Code:
\documentclass{article}
\usepackage{showexpl}
\usepackage{tikz}
\lstdefinestyle{myLatexStyle}{
language=TeX,
basicstyle=\small\ttfamily,
backgroundcolor=\color{yellow},
numbers=left, numberstyle=\tiny, stepnumber=2, numbersep=5pt,
showstringspaces=false,
keywordstyle=\color{blue}\bfseries,
morekeywords={align,begin},
pos=l
}
\begin{document}
\begin{LTXexample}[style=myLatexStyle, pos=b]
\begin{tikzpicture}
\node [rectangle, draw, fill=blue!20, text width=5em, text centered,
rounded corners, minimum height=4em] {test};
\end{tikzpicture}
\end{LTXexample}
\end{document}
## 2. Replace \node macro:
The above solution will only show the code that is within the LTXexample environment. So if you still wanted to use a separate drawing macro, the above would only show \theCommand{test}; in the output, which does not provide much information. An alternative is if you replace:
\newcommand\theCommand[1]{%
\node [rectangle, draw, fill=blue!20, text width=5em, text centered,
rounded corners, minimum height=4em] {#1};%
}
to use \ShowAndExecuteNode instead of \node:
\newcommand\theCommand[1]{%
\ShowAndExecuteNode[rectangle, draw, fill=blue!20, text width=5em, text centered,
rounded corners, minimum height=4em]{#1}%
}
then you get the output:
Commenting out the \AtEndDocument{\TikzCodeList} will eliminate this output.
## Code:
\documentclass{article}
\usepackage{tikz}
\newcommand\TikzCodeList{}%
\AtEndDocument{\TikzCodeList}%
\newcommand{\ShowAndExecuteNode}[2][]{%
\node [#1] {#2};
|
# Tag Info
## Hot answers tagged aes
5
Given the choice, it is preferable to use the block encryption operation of AES, since it often faster than block decryption (never slower AFAIK). For this reason, AES-CTR is defined to use the block encryption operation of AES exclusively; that's both for AES-CTR encryption and AES-CTR decryption, which are the same operation except for IV generation/input. ...
4
Do not invent your own authenticated encryption mode. Use a standardized one, and use a well-supported library to implement it in your code. AES-GCM, AES-CCM, AES-OCB, and AES-CBC with HMAC-SHA256 over the ciphertext are all common options. Some great direction from Matt Green here: How to choose an Authenticated Encryption mode
4
Yes, this is exactly what a message authentication code is for. Its job is to prevent an attacker from tampering with your message, or from forging completely bogus messages. (And no, a secure MAC cannot compromise your key; if it did, it would by definition not be secure, since an attacker could use the key to forge messages.) However, you probably don't ...
3
No the IV doesn't get encrypted. The IV is a random vector to make sure that the ciphertext is not identical for identical plaintext. This would leak information to any eavesdropper. It needs to be unique - and in the case of CBC, indistinguishable from random to the eavesdropper ("unpredictable") - but not confidential. As the IV is separate from the ...
3
Yes, this is secure, even though scrypt uses PBKDF2 inside. PBKDF2 has the issue that it the work factor is required $n$ times where $n$ is the number hash outputs concatenated to create the final PBKDF2 output. That means that if you can check the validity of PBKDF2 using only the initial bits (in your case used for the key if the hash was SHA-256, for ...
3
In RFC2246, if you need 12 bytes of padding total, that means that you have 11 padding bytes, followed by a padding length field. So, each padding byte has a value of 11 (0x0b), as well as the padding length field. This is implied by the requirement that the total TLSCiphertext.length must be a multiple of the block size, and this TLSCiphertext.length ...
2
ECB is not secure even with per file keys, because if two blocks of the file are identical, this is visible in the ciphertext. The only * cases where ECB is secure is encrypting completely random data or encrypting a single block per key. You should pick something more secure if your can help it. If there is literally no other option than RC4 and AES ECB, ...
2
NIST requires 128 bits of entropy to seed CTR_DRBG with AES-128, so you can safely assume that. If you ask for 256 bits of data, there is theoretically a chance that an attacker could be able to attack the RNG with a 128-bit attack: Suppose a 256-bit random value is requested twice and the attacker sees the first one, which we denote by $x_1||x_2$ (two ...
2
Both the AES key size and the RSA key size matter, because it's no use adding security beyond the weakest link. Here the weakest link is 2048-bit RSA, which is considered roughly equivalent in security to 100-128-bit symmetric keys (depending on who you ask). So having a password with much more than 100 bits of entropy would be fairly useless. In practice, ...
1
The one you have in hardware. Sometimes the hardware only supports block encryption (because it is sufficient for e.g. CTR), in which case that will be faster. If the hardware supports both, there is probably no difference. I doubt many implementations only support decryption, but if you have one that does, that would be faster. The speed of raw ...
1
It is usually seen that decryption operations are slightly faster than encryption. But considering the working mode of AES, CTR uses same steps in both encryption and decryption. So It does not matter which one you use in CTR, both should give essentially same performance.
1
Let's look at some simpler relations first. I'll be sloppy with the probabilities, I'm only trying to gauge the order of magnitude. The probability that $E_{k_1}(p) = k_1$ is $2^{-128}$ for a given $p$, but must be true for some $p$ with every AES-128 key $k_1$. The probability that $E_{k_2}(p) = k_2$ for the same $p$ is $2^{-128}$ for a given $k_2$. The ...
1
Would there be a minimum ciphertext size that is related to the public key size? It depends on the algorithms used. An RSA signature, without any bells and whistles, is equal to the key length in size (i.e. 2048 bits for 2048-bit RSA). Likewise raw RSA encryption adds the same. So if you just use both, you add twice the key length, or 512 bytes for a ...
1
Well, firstly, SHA-1 still seems to have 160-bit preimage and second preimage resistance, so using it in HMAC requires more than 128-bit AES keys to get equivalent security. AES 192 would be sufficient, but isn't used in e.g. TLS – RFC 3268 says: The AES supports key lengths of 128, 192 and 256 bits. However, this document only defines ...
1
There's nothing wrong with using CTR mode to encrypt files, or anything else, as long as you make sure to use every nonce value only once. (And add authentication, if malleability would be a problem.) You could, for example, rewrite the whole file encrypting it with a new random nonce every time it's modified. Since you are assuming nonce reuse, an attack ...
1
Using the same key and IV for different, independently encrypted cells is a bad idea, regardless of which encryption algorithm you use. It would allow attackers to find either XORs of cells (with CTR) or at least equality of prefixes (with CBC). If you are going to use authenticated encryption, you need to choose whether the MAC applies to each cell ...
1
Is there a standard or at least "commonly used" format to format the result? PKCS #7 (and CMS which is a further development) describes a standard format for encrypted data. While it's mainly meant for public key encrypted data, it also has options for symmetric keys. It's rather complex due to all the features it supports, however, so unless you can ...
Only top voted, non community-wiki answers of a minimum length are eligible
|
## Cryptology ePrint Archive: Report 2016/1132
Some results on ACORN
Abstract: In this paper we obtain a weakness in the design specification of ACORN, which is a competitor of CAESAR competition. We show that there exists a probabilistic linear relation between message bits and ciphertext bits, which holds with probability greater than $\frac{1}{2}$. This is the first paper which finds a probabilistic linear relation between message and corresponding ciphertext bits of ACRON, and which holds with probability greater than $\frac{1}{2}$. We also propose a new type of CPA attack on ACORN. By our attack method, it is possible to recover full initial state of the encryption phase of the cipher, and the attack has complexity $\approx 2^{40}$. After obtaining the initial state of the encryption phase, one can invert the associated data loading phase and key-IV initialization phase to recover the secret key bits.
Category / Keywords: secret-key cryptography / CAESAR, ACORN, linear approximation, CPA.
Date: received 5 Dec 2016, last revised 25 Dec 2016
Contact author: dibyendu roy1988 at gmail com
Available format(s): PDF | BibTeX Citation
Short URL: ia.cr/2016/1132
[ Cryptology ePrint archive ]
|
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