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Mass appears to attract other mass, irrespective of position or orientation. That is, gravity is attractive no matter what. Contrast that with electrostatic forces which could attract or repel depending on the charges involved, or a voltage between two metal plates which has a specifically directional force on electrons travelling through it. How do we know gravity attracts in all directions at once? What experiments have been done to confirm this? | 1 |
There's a word, I think that starts with a 'p', that describes doing something to solve a situation before it happens. For example, if a hurricane is approaching a store might take __ action to prepare for the flood of people that might come. In a fictional world, an organization might take __ action against crime based on some foreknowledge of a person's future actions. Edit It's not "preparatory", "precautionary", or "preventative". | 1 |
I'm looking for a word that is used quite often to mean something that feels real like you can reach out and grab it. Like it has substance. It's used most often around me to refer to user interface or game design. Like when a UI has weight and feels like it has substance behind it you say it's ............... I originally thought of... Visceral Corporeal Ephemeral (although I was looking for an antonym of this) But none of them are correct. But it is a word with the same "al" ending I think. | 1 |
As the title indicates, I'm trying to find books where the exposition of the main course of thought is done entirely or mostly in outlines of proofs, or as exercises with or without hints. I'm trying to force my reading to be more "active", and I think that such a book would be good training-wheels. No particular topics, but preferably something on the introductory level. I'm particularly interested in basic Differential Geometry and/or Algebraic Topology related topics right now. (I have "undergraduate level" background in Real Analysis, Abstract Algebra, Linear Algebra and General Topology, and I'm trying to get started with Algebraic Topology and Differential Geometry for my own personal and educational enrichment.) Texts on other topics would be welcome for later reference. Much thanks. | 1 |
I just finished reading (and understanding) Steiner's proof of the isoperimetric inequality. His proof (which is sadly incomplete) seems to rely much on the fact Steiner symmetrization preserves area and decreases perimeter. The only resource I've found which provides proof of those two things are Andrejs Treibergs' beamer slides , however ,they are confusing as he is a bit heavy on notation. Can someone please point me in the right direction on where I could find an alternative resource providing detailed proofs. If possible, a proof if you don't know a resource would be highly appreciated. | 1 |
Person A says to B: "I thought you were smarter/stronger/better/more trustworthy than that. I should have known better." I was thinking it would be termed passive aggressive, but after reading up on it, that doesn't seem right. I'm tripped up on how focused on the Person A the two sentences are. Typically an insult would be "You're not very smart" and that would be that. But this is "I'm disappointed in myself for thinking better of you." Is there a good term for this sort of insult? | 1 |
I have been using Windedt with Texlive since many days. But I stopped using it for a while, and when I now compile a tex file, its giving error "The system cannot find the file specified". I don't know wats wrong. I have used this before. I tried re-installing Winedt, no use. I have recently changed the System Path for installing some software. Has it affected in anyway?? Please help me. | 1 |
Please have a look at these two definitions: Chevalley-Eilenberg complex Koszul complex (German Wikipedia) Both are from Wikipedia pages on Lie algebra cohomology, and they look rather similar. Since I'm not very solid on the notation, I'm unsure about what's the difference between them. Furthermore, since both Wiki pages are about Lie algebra cohomology, and no page defines the "other" chain complex, I'm not even sure whether they are different at all. What's the essential difference between them? | 1 |
Does a definition need to provide a unique or near-unique description or can non-unique descriptions also be categorized as definitions? For example: Is the statement "An apple is a fruit" a definition of apple? Is the statement "A car is something that gets people from place to place" a definition of car? Are these simply descriptions (or categorizations) of the objects in question or are they also poor definitions? | 1 |
I've got a sci-fi based Physics question that involved Dark Energy... So I've been watching a lot of Doctor Who recently, and I'm very interested on how his "Tardis" is bigger on the inside. Here you can see the Tardis looks small on the outside. But inside, it's much bigger. So here is what I've been thinking. What if you got a box (like a Police Box), and somehow filled it with Dark Energy! Im hoping that the Dark Energy would expand space inside the box, thus making it "bigger on the inside". My question is, could this actually work? Thanks for your help. (This is just a fun question btw) | 1 |
Just as the title says: is there a formal name for a convex polygon on a sphere, of which the vertices are connected not by great circle but by small circle segments? My end goal is to intersect two (or more) of such shapes, and find the area of the shape where the two small-circle polygons overlap. It would therefore be helpful to get to know some basic and/or special properties of such shapes, what equations apply, etc. | 1 |
I'm trying to get the facts straight here. Suppose I'm throwing a ball with no angular momentum. It collides with the ground and Newton's third law tells us that a force opposite to the gravity will be applied to the ball at collision. During collision, the momentum will be converted to potential energy and then become kinetic energy again. Am I right to say that some of the kinetic energy can be converted to angular momentum, thus making the ball rebounce not straight up? (assuming some friction) | 1 |
It's just a casual observation, so I wanted to check it: A regular spring, when not completely compressed, looks an awful lot like a sine wave. The idea of a circular shape stretched out in the third dimension also seems to support it. But I can find no mention anywhere that such a spring actually is (or isn't) shapes like a sine wave. I don't want to tell my pupils this unless it is more than just an observed similarity. So is a stretched spring, if seen from the side, shaped like a sine wave? | 1 |
I want to read particularly about diophantine Analysis and Elementary Number Theory from a novice level. The books which I found on net: A Guide to Elementary Number Theory by Underwood Dudley Diophantine Analysis by Robert Daniel Carmichael Diophantine Analysis by Jorn Steuding Help me with good suggestions as I think M.SE. has people from novice to professional users. Thanks. P.S. I have searched M.SE. for this type of question, I didn't find any. If you know someone, you may give the link. | 1 |
What are some quantities often used to measure the sparseness of a graph? For example, in a graph, with the number of vertices fixed, the smaller the maximum degree is, the more sparse the graph is. With the maximum degree fixed, the bigger the number of vertices is, the more sparse the graph is. For another example, the more sparse the adjacent matrix is, the more sparse the graph is. Then it leads to another question: what are some quantities to measure the sparseness of a matrix? Thanks! | 1 |
I would like to know if a discontinuous local martingale with paths of finite variations almost surely is a martingale. I feel that it should be the case but can't find a straightforward argument. As noted by Did in its comments below, the continuous case follows easily from the widely known fact that continuous local martingales have paths of almost surely infinite variations. So I modified the question to make it more specifically about discontinuous local martingales. Best regards. | 1 |
Prove that a) the medians b) the altitudes and c) the angle bisectors drawn from the base angle of an isosceles triangle are congruent. Looking at this problem, I feel that this statement is just false. If you have an isosceles triangle given in the following link Link. Then clearly these are not congruent. Is there something in the problem that I am missing? Thanks | 1 |
I was told that a dielectric slab inserted into a capacitor connected to a battery (constant voltage) will be repelled, because the energy stored in the capacitor increases when the dielectric is inserted, due to increased capacitance. What is the physical origin of this force? The attractive force by a constant charge capacitor can be explained by fringe field, but why are the two cases different in terms of forces? | 1 |
What is the official rule when mentioning a city/ state in a sentence? I always thought there was a requirement for a comma between the city and state, however is there also supposed to be a comma afterwards? Tim also enjoys football games, jumping on his motorcycle and being a guide for the Fredrick, Alabama, restaurant scene. I personally think it looks clunky, however I'm told that it is opinionated and that the above is correct. Should the sentence be written like this? Tim also enjoys football games, jumping on his motorcycle and being a guide for the Fredrick, Alabama restaurant scene. | 1 |
I am new to studying abstract algebra (and math in general). I've been reading Gilligan and Pinter's books. I am trying to improve my understanding by doing exercises. However none of the books I am reading seem to come with exercise solutions. Is there an abstract algebra book with lots of exercise with solutions? I am confused as to why none of the math books come with complete exercise solutions. How do people verify that their answers are right. | 1 |
Using packages like minted (thanks to Pygments), LaTeX can generate beautifully highlighted/colored source code. Literate programming tools such as noweb and cweb can generate beautifully typeset and readable documentation. Ideally, I would like that the docs generated by noweb and cweb have high quality syntax coloring, and this seems like a problem that someone on either community may have tackled. So here is the question: Does anyone know how to get noweb and related tools to use minted or a similar LaTeX package for syntax coloring? | 1 |
I saw in my abstract algebra textbook that defines the gcd of a polynomial over a field (i.e. the coefficients of the polynomial is taken from a field). My question is that what happens if the field is not a real numbers? I mean intuitively, I always think of it as real numbers. Is there anything wrong in taking of it this way. Can someone give me an example of a polynomial taken from other fields such that thinking of it as real numbers will result in a misconception. Thank you. | 1 |
Is there any text that I can use as a short reference for the standard techniques for solving basic ODEs? I currently have been using Boyce and diPrima as my ODEs text, and it is far too wordy for my taste. I'm also not too interested in expositions of applications of physics or phase plane analysis, as I have other books for that. Basically, I'm looking for something short that can quickly remind me how to use techniques like integrating factors, series solutions, etc. which I keep on forgetting. | 1 |
I have two matrices(the first one is mxm, while the second one is nxn, m>n). They store data pertaining to human speech. The second matrix contains a data segment that acts like an acoustic "signature". I need to find where this data occurs in the first matrix. Which mathematical tool(s) or method(s) can I use to get it done? I know convolution can help me out but is this the best(more importantly fastest) way? | 1 |
For each relation, determine which of these properties are present: reflexivity, symmetry, antisymmetry, and transitivity: I know the definitions of each of the properties but unclear as to how to apply them to each relation. {(a,a), (a,b), (b,a), (c,c), (d,d)} {(a,a), (a,b), (a,d), (b,a), (b,b), (b,d), (c c), (d,a), (d,b), (d,d)} {(a,a), (a,b), (a,c), (a,d), (b,b), (b,d), (c,c), (c,d), (d,d)} Does anyone know what I would need to do to solve this? | 1 |
I'm looking for an adjective that describes that tasks should be approached "one-ly". To give some context: [Task] must be performed in one way and exclusively one way. or There must exist precisely one method of performing [task]. I am looking for an adjective that describes this "one-ness". The adjective does not need to specify what the method is, it should merely prescribe that the task should be approached in precisely one way. The closest word I could think of is "uniform". | 1 |
I just came across the term quantifier-free first-order formula, I first thought that might be similar to a propositional formula, but then after a closer evaluation I realized there are more concepts in first-order logic then just the quantifiers. I believe the difference is the following. A quantifier-free first-order formula can still contain: Function symbols Predicates where as a propositional formula does not have these concepts. Is that correct? Did I miss something? | 1 |
Please compare He shrugged. and He shrugged his shoulders. Is there anything else that can be shrugged, besides shoulders? To me it sounds like duplication when used in this way. I'm aware of constructs like "He shrugged it off." but that's not what I'm interested in, and it also implies the use of shoulders, doesn't it? So why the need to specify the shoulders as an object? [edit: I also find "he shrugged his eyebrows" but that's rather rare.] | 1 |
Does the expression "to add another dimension to the situation" imply that the situation has become more complex? In Arabic we would say something like "adds another dimension to the situation that has become more complex". But I know English tends to be very economic and implicit. So if I wanted to express that idea, would "adds another dimension to the situation" be enough? Or do I have to say that the situation has become more complex? | 1 |
The statement of the Cayley-Hamilton Theorem is fairly straight-forward. I now know how to find characteristic polynomials from a given matrix (or at least a matrix with certain properties that I am unaware of!). I know that the eigenvalues of the matrix are roots of the polynomial. But what does having such a polynomial mean? Wikipedia says that the characteristic polynomial "...encodes several important properties of the matrix...", but once we have switched to "matrix form" of the equation, what can we conclude? In other words, what does the Theorem do for us, besides allowing us to say, "Hey, I know a matrix solution to this polynomial"?? Is there an abstraction of this in abstract algebra (rings, fields, etc.)? Thanks for your time. | 1 |
Is there a name for the practice of composing sentences in such a way that they don't contain proximate consonants which cause difficulty when read aloud? For example: Under this criteria, "dogs and cats" is preferable to "cats and dogs," because the consecutive d s in the latter are difficult to pronounce clearly and distinctly and will force the speaker to either interrupt the flow of speech or elide the first d. | 1 |
During a sunny day the walls of my house warm up (no surprise). My question: how much of this warming up (if any) comes from visible light? I associate infrared with thermal energy. If my house was floating in space (to prevent any thermal exchange with its surroundings) and I installed a giant infrared (and UV) filter between it and the sun, would it still warm up (compared to its rest temperature in full darkness)? | 1 |
Does a matrix with all non-negative, real entries have all non-negative, real eigenvalues? Where might I find a proof of such? Ideas: Perhaps we can multiply a prospective eigenvector so its biggest entries are positive, and then show that it is a contradiction for it to have a negative eigenvalue? I am currently looking at the Perron-Frobenius theorem on Wikipedia, but it seems not to mention this issue. (I suspect my conjecture is not true.) | 1 |
I think the title says it all. I am planning on giving a talk in a few weeks about the Banach-Tarski paradox and I have some pdfs found online which describe the paradox a little but I am looking for a solid reference which covers the construction from A to Z and on which I can extract the main ideas for my talk from (I understand the ideas beneath the paradox, I am just looking for a formal proof with no details excluded,i.e. a well-structured document). Anyone has a reference in mind? | 1 |
For instance, would you rather say "It became increasingly hard" or "It became increasingly harder"? From my understanding, both are possible, but their meaning is slightly different. The first simply means that it became "harder". The second literally refers to an increasing rate of getting harder. Though in practice, I believe the second is still used to express the exact same as the first, while sounding somewhat awkward. | 1 |
I am looking for a specific word to describe a concept such that its meaning is linear and one-way. Such is the case for the title of this question. X would be of this concept and Y would not, Y would be the opposite of this concept. For example, all automobiles are motor vehicles but not all motor vehicles are automobiles. I cannot seem to find any word to relate to this. Any advice/guidance is very much appreciated. | 1 |
Traditional English prescriptive grammar teaches that these two verbs, to see and to hear, when describing their sensory nature, should never be used in the progressive aspect of tenses. Thus I am seeing you/I was seeing I am hearing you/I was hearing you would be incorrect. But in spoken English, whether it be in the movies or on television, this usage seems to me to become ever more often used. I am seeing you for I see you now I am hearing you for I hear you now When did this usage become so universally accepted? Is it still considered colloquial English? Or is it already considered standard English? | 1 |
I would like to create a table (cf. attached figure) and use curly brakes to summarize some of the cells. I did a lot of research and found this solution (Curly brackets around a table), but it doesn't help me much as it is only math content and I would like to enter text only. Does anyone have an idea about how to solve this problem elegantly? Cheers | 1 |
I realize there are questions on the correct usage of "but" and "however". In this case, I am concerned with correctness in a formal context. I have heard it said that however should be used in formal mail communications instead of but because the word "but" has a negative connotation. Which should I use in, say, an email to a client? Examples: We understand the issue you have pointed out, but we cannot consider it as a defect in the application since the current behavior was requested by your team. We understand the issue you have pointed out. However, we cannot consider it as a defect in the application since the current behavior was requested by your team. | 1 |
As I read on Wikipedia, the Rutherford atomic model is not correct according to classical electrodynamics, as it states that electron must radiate electromagnetic waves, lose energy and fall onto the nucleus. I don't understand this explanation. It is clear to me that with given acceleration directed to nucleus and proper speed, electron can move around the nucleus. I don't understand explanation about energy, but I understand that there must be some force directed to nucleus. Also this force must not be constant because if it is, a larger speed could keep electron moving around the nucleus. So what is that force? Why does this explanation on Wikipedia and on other resources operate with energy, not with force? | 1 |
I'm reasonably happy with the dictionary functionality in TeXworks but I am struggling to see how I can 'find' all the spelling mistakes in my (painfully long) tex file. I was hoping for a Wordesque spell checker in which I can scroll through each of my errors and accept or ignore the suggested changes. I could install another editor that has this functionality but would prefer not to do this if possible. | 1 |
I am wondering if the verb expect is used as a stative verb in the following sentence: I entered the classroom and [to expect] to see some students but instead I found a note which said [...] Would it be possible to say "I was expecting"? Or is the verb stative in this context? Because then we can't use it in a continuous form, according to my grammar book. | 1 |
Can anyone please explain why light reflects at the boundary between two regions with different impedances? This sounds very simple but I got confused when I tried to think of how light and atoms interact with one another at the boundary. This question can actually be generalised to the reflection of all types of waves. I have to admit I have no understanding of the microscopic detail of reflection. | 1 |
I believe I am stuck with only these two options, but would appreciate an alternative usage. I am somewhat limited on sentence structure as this application is part of a mail merge document. The purpose of the business is to own and operate The Tutoring Center franchise location. OR The purpose of the business is to own and operate a The Tutoring Center franchise location. Since the business will be a franchise (one of many), I feel the article "a" is necessary. Help is much appreciated! | 1 |
What are the desirable pre-requisites to be able to learn model theory well? In particular, it seems that connections to algebra are used heavily especially as examples. I would like to know if a good grasp of algebra is essential for a deeper understanding of model theory and whether a good grasp of analysis and topology would compensate for lack of the former. Thank you. | 1 |
I have started learning some basics of Category Theory.Currently i am trying to understand the concept of Direct limit and Inverse Limit but i find this concept really hard to digest. Could some one explain me with some details the good idea to think about Direct Limit and Inverse limit in practice? I have knowledge of subjects like Module Theory,Galois Theory,Commutative Algebra(at the level of Atiyah Macdonald),Basics of Lie Algebra and of course elementary topics like Group theory and field theory etc. | 1 |
I'm interested in using TikZ to draw rooted trees whose leaves should all be on the same level, pretty much like this: Please don't pay attention to the fancy style and colours, I'm only interested in having all leaves at the same level. Anyone knows how to do this? I've looked into the manual and the appropriate section on Texample, but had no luck so far. UPDATE: a while after this question was answered, I found out about the LaTeX newicktree package, which allows you to draw such trees in an extremely simple way, just by specifying them in the format people in phylogenetics already use. This is obviously much simpler than resorting to TikZ, but thanks anyway to everyone who contributed to helping me. | 1 |
My understanding is that dark matter cannot be (or is at least highly unlikely to be) an exotic form of any known particle. On the other hand, articles about particle accelerators seem to say that the Higgs is the last piece missing in the Standard Model jigsaw puzzle. If dark matter is determined to be some form of new particle, what are the certain implications? Might such a discovery "stand to the side" of the Standard Model or would it certainly change the foundations? (Forgive my extremely lay understanding and vocabulary -- please feel free to correct my mistakes.) | 1 |
If I pick up a rock and set it on a ledge above my head, I do work in the process. The work I do is termed "potential energy". We know how to recover the energy (i.e. let it fall back to earth). However, while resting above the surface the energy is said to be "stored in the gravitational field", presumably meaning the space between the elevated rock and earth. Suppose we perform this experiment on the moon where we know the space between the elevated rock and surface consists of an empty vacuum of space which contains absolutely nothing. How can empty space store energy? That is, how can "nothing" have any properties whatsoever? | 1 |
I was writing an email and faced the following situation: I am coming to Oxford this summer. If you are still around, I would be glad to hang out with you. Now normally we don't construct the conditional statement like the one above, where a present verb is followed by would. But if I change the second one to will it kind of becomes very direct and that's not what I want. So is the construction above still correct or should I go with something else? If it's correct, could someone explian the technical details behind it? | 1 |
Im studying old exams and came across this one Question: a. Find a (discrete time or continuous time) random process that is wide-sense stationary (WSS) but not strict-sense stationary. b. Also, is it possible for a strict-sense stationary random process not to be wide-sense stationary? Answer: a. A sequence of uncorrelated random variables with common expected values and common variances constitute a WSS discrete time process, but is not strict-sense stationary if the random variables are not identically distributed. b. A seqeunce of independent identically distributed random variables with infinite variances constitute a strict-sense stationary discrete time process that is not WSS. a. Can anyone give a simple example of such a process? b. Our course litterature says WSS processes are always strict-sense stationary?!? | 1 |
I remember being presented a mathematical puzzle some years back that I still can't solve. The problem is defined as follows: We have two points on a plane, and using only a compass, how do we find other two points, so that all four of them would be vertices of a square? I'm not sure whether the first two points were supposed to be vertices of the same edge of a square or not, so solutions to both variants are welcome. | 1 |
I know the word uxorious that is used to describe a husband who dotes on his wife excessively. What is the corresponding word for a wife who loves her husband dearly? I cannot pull anything out of my memory... and I feel it is very harsh on men if such a word weren't there! Example: He was an uxorious man who assiduously took care of all of his wife's needs. She was a __ woman who assiduously took care of all of her husband's needs. | 1 |
I don't know if the title of this question is accurate or not. My vacabulary of grammar is very limited. May you could understand me by the following example: She told me that the earth is moving around the sun. She told me that the earth was moving around the sun. Which one is correct? Should the tense in that clause always agree with the tense in main clause? | 1 |
A lot of text books mention that one of the reasons that classical mechanics failed to explain atomic and subatomic processes is that electrons which accelerate should release energy in the form of electromagnetic radiation, which would lower the atoms overall energy level, but this does not happen. One place where I discovered this, for example, is in the description for the Bohr model. What I don't understand is why everyone takes for granted the fact that the electron is accelerating. I thought the electron orbits the nucleus at a, more or less, constant velocity. Are people referring to specific situations when the atom is excited? Furthermore, I was under the impression that electrons already travel at the fastest allowable speed, the speed of light. | 1 |
Okay, I am in no way a mathematics student but I happened to be writing a program on a map with coordinates of locations displayed on the map. My problem is that the points could be scattered on the map with an indefinite boundary and I need to find a boundary (rectangle) around these points and thus I need to get a formula to form an algorithm so that the program will find the optimum boundary itself. I hope this is understandable and thanks in anticipation of any response. | 1 |
I'm a high school student. The head is hydrophilic, the tail is fatty acid, in other words hydrophobic. Here is the thing I don't understand, all textbooks state that water is repelled by hydrophobic tail, why? The hydrophilic head is composed of polar molecules, and water is polar, so they will attract each other. But why hydrophobic tail will repel polar molecule? Isn't hydrophobic tail is just composed of non-polar molecules? | 1 |
Consider this situation: You sent an application for a job, then the company boss sends you an email, and tells you if you are in town, he likes to meet you in person. Is it correct to say? "It could have been a great pleasure to meet you, but unfortunately I am currently in Russia." I'm not sure what tense I should use, and I'm pretty sure the above sentence is incorrect. At the same time, I want it as much as possible in a formal and polite way. | 1 |
I am trying to use IEEETrans to write a scientific paper in two column format. The issue is that one is not allowed to place figures in the left-hand side column of the first page. Figures should start on the top of the right-hand side column of the first page or alternatively, on the second page (any column). Is there any way to restrict the placement of floats to avoid using the left-hand side column of the first page? | 1 |
In sports, we have the term "Commentator's curse", (humorous) The supposed propensity of a player to blunder after having his/her talents pointed out by the commentator. [Wiktionary] Is there a phrase that emphasizes that the sportsperson performed brilliantly soon after the commentator's talk highly about their achievements? For instance, a Cricket player hitting a six immediately after the commentator says that he has the highest number of sixes for his team. Or a Football (Soccer) player scoring from way outside the D-box just when the commentator says that the player had scored from a similar distance in the previous game. It might be termed as "pure co-incidence" but I'm just looking for something humorous/ emphatic as "commentator's curse" itself. | 1 |
I know that massive gravitational bodies will curve the path that light travels. I think that quantum optical mediums also bend light. I am still confused of whether quantum optical mediums actually slow down light or if they just use absorption, re-emission, scattering, and delaying to create the illusion that light slows down in a medium. I do not see a fundamental difference between the two theories, because both describe "optical" phenomena of light. I am not sure if gravitational optics is a real field of study or a made up name. My question is there a mathematical equivalence between gravitational optics and quantum optics or are they mathematically incompatible theories? | 1 |
Most of the references I found online simply note that "see you later" is a farewell or parting phrase but nothing discussed when it is appropriate to use the phrase. Is it acceptable to use "see you later" in each of the following circumstances? When you will be seeing the person again later that day When you will be seeing the person soon (e.g., in a few days) When you will be seeing the person again at some point in the future (e.g., next year at Christmas) When you are suggesting that you want schedule something specific Whenever you say goodbye, regardless of whether or not you will ever see them again | 1 |
I am reading up on splines and as a beginner I have a basic question - Does it make sense to say - "I will fit a cubic b-spline to the data". As b-spline is just a representation of spline in terms of its bases. I think, a more accurate statement will be - "I will fit a natural/not-a-knot/clamped/etc. cubic spline to the data and present results in terms of its basis." My question arises out of my limited understanding of relevant concepts. Could someone please confirm this. Many thanks! | 1 |
At the moment I'm a bit baffled. What sentence part is "visitors" in "I'm not allowed visitors"? I would not call it an object or a subject complement as "to be allowed" is no linking verb. The only idea I have is to say the sentence is elliptic and the full form would be "I'm not allowed to have visitors". Here "visitors" is object of the to-infinitive. So is it possible to say "visitors" is object of a to-infinitive (to have) that was deleted? | 1 |
As far as I understand, the incident photon interacts by photoelectric, Compton scattering or pair production with the electrons of the crystal (NaI(Tl) in our case). The electron that emerges from these interactions generates a number of photons in the UV or visible which are proportional to the gamma ray energy. Then, the light produced can be read out with photodiodes, photomultpliers, avalanche photodiodes, silicon photomultipliers, and other photo sensors, right?. So, how are those electrons converted into UV or visible photons? | 1 |
I've read here that microwaves are blocked by the holes in a microwave window because the holes on the door are small enough to prevent the microwaves from passing through. However, if wavelength is only the distance between successive crests of a wave, why should that decide what a certain wave can fit through? Why is amplitude not the deciding factor and is there a way to explain this visually? | 1 |
Projectiles containing delicate elecrtronic equipment may be damaged if they are subjected to high accelerations. For this reason, such projectiles may be fired from guns with long barrels but not from guns with short barrels. -Explain why a projectile fired from a long-barreled gun is subject to less acceleration than a projectile fired from a short-barrelled gun if the range is the same in both cases. This question has been a nightmare for me when i was in highschool and until now i cant have a good answer your help would be appreciated. | 1 |
I am new to LyX so I'm sorry if this question is really naive. I'm using LyX on a MacBook and I'm hoping to use the AEA document class on it. Since it is not available automatically, seems that I need to somehow install it on my own. All the help pages I can find talks about layouts and stuff that I, as total layman, have no idea what they are. Can somebody please show me how I can do it with simple language? | 1 |
I'm reading about how a "straight line" depends on the geometry of space. While I think I understand this, the example people give is: "Imagine a straight line on earth connecting two cities. It's actually curved because the earth is curved". My response to that would be "Well no, because a truly straight line would cut through the earth. Like a straight string would cut through an apple". So question: If two people took an infinitely strong and light string, stood on opposite ends of the earth, and pulled almost infinitely tightly, would the string curve around the earth a few feet above, or would it cut through to the core? | 1 |
I am currently reading the following paper by F.Takens: Multifractal analysis of dimensions and entropies. This paper discusses two different measures. One is generalized entropies and the other is generalized dimensions, however as far as I can see it doesn't discuss any association between the two. Can somebody please in a qualitative or [even better] quantitative give me an explanation about the relation between the two? | 1 |
Our course slides offer the following definition: "A parametric probabilistic model is a set of probability distributions indexed by a finite-dimensional parameter vector." This description defines "parametric probabilistic model" in terms of "parameter", which isn't particularly helpful. But it brings to mind some vector of indices which tells you where to find a row (or rows) in a table. It is not clear to me whether "parameter" in this sense is related to my CS understanding of a parameter (i.e., a "knob") or even if a model's parameters have something to do with its random variables (e.g., are the parameters fixed values of a random variable?). Furthermore, what does it mean to "parameterize" a model? | 1 |
I have this question on a homework assignment. I sat down with two other people for a long time and we derived the alternating harmonic series example, but I don't think that's valid because the question explicitly asks about sequences and not series. Note that it's for an analysis class and so far we've covered open and closed sets and balls, preimages, and cluster points. | 1 |
I've read through answers to similar questions, and I haven't been able to find a satisfying answer. I've heard it said that in order to make out something, you need to use light with a wavelength at least as large as the object. In what way can you mathematically derive this heuristic? Moreover, does this apply generally? The other day I was thinking in the context of sound waves and how fruit bats use them to resolve insects- is this a reason why they use high frequencies? | 1 |
Question: What are some interesting or useful applications of the Hahn-Banach theorem(s)? Motivation: Most of the time, I dislike most of Analysis. During a final examination, a question sparked my interest in the Hahn-Banach theorem(s). One of my favorite things to do is to write a math blog (mlog?) post about various topics so that I can better understand them, but I know very little about Hahn-Banach and a quick google search didn't seem to point to anything neat. I was interested in seeing what you all liked (if anything!) about the Hahn-Banach Theorems. Also, I can't seem to make this a community wiki, but I think it ought to be one. If someone could either fix this, I would appreciate it! (If not, please delete this!) | 1 |
is it possible to use participial prepositions in the following sense, or am I creating a dangling modifier. Moreover, is the punctuation correct? Considering his broken leg, Peter was not able to walk anymore. Peter was not able to walk anymore considering his broken leg. Understanding Einstein's statements is neccessary, since Peter wants to graduate in Physics in order to get a good job. Since Peter wants to graduate in Physics understanding Einstein's statements is neccessary, in order to get a good job. Can participial preposition be used as subordinating conjunctions? Maybe a native could help me out here. Thanks! | 1 |
Special relativity theory says simultaneity is relative, meaning that different observers will not agree on what happened first and what second. Does it then make sense to say that looking at distant stars, we see them how they looked "billions of years ago" and not how they look now? Does it make sense to talk about what these stars look like now? How do we define this "now" if simultaneity is relative? | 1 |
So there is this kind of building located in the centre of a fork in the road (maybe in streets too). I don't know how to put it into words, but it looks like this: Or this: Is there a single English word for that kind of building? If it is a house, is there another name for that? In my native language (Indonesian), it's called Rumah Tusuk Sate. Which if translated bluntly into English, it's Skewer House, which sounds a bit weird to me. | 1 |
Possible Duplicate: Why the use of 'would' in the following When we tell a joke or narrate a story in simple present can we use 'would' in some cases? For example: He goes up to this man and punches him in the face. The man looks straight into his eyes and tells him that he will take revenge He goes up to this man and punches him in the face. The man looks straight into his eyes and tells him that he would take revenge | 1 |
According to this extract from Wikipedia, the pronunciation of the term piste meaning "a ski run of compacted snow.": varies slightly in English, with British English using a long "e", (e.g. rhymes with "beast"), and American pronunciation using a short "i" (e.g. rhymes with "list"). Actually, references such as the Cambridge Dictionary or the ODO suggest that the pronunciation is the same in both dialects, that is, with a long "e". Does the AmE pronunciation of "piste" really differ from the BrE one, or are both versions correct? | 1 |
I am finding hard to understand application of inclusion and exclusion in Matching problem? Suppose that n- n male-female couples are at a party and that the males and females are randomly paired for a dance ? what is the probability that none of the couple are paired together? I don't understand why we have to take Union then use inc-ex principle to solve it? Can some one help me to understand ? Thank you | 1 |
I'm struggling to find a way to express the idea that it's possible that something was done before something else was done. I'm not sure if I'm just tired, but the idea is this: In the present perfect, you would say "it has been done before". When you add "may" it becomes "it may have been done already". In the perfect past, you would say "it had been done before". How does that sentence look like when you add "may" to it? "It might have been done before"? "It may have been done before"? Or even "it may have had been done before", as clumsy as it sounds? None of these sound particularly correct, so I'm at a loss as to what the solution here is. | 1 |
If we consider two spins, we can think of the spins as being either parallel (up|up or down|down)or anti-parallel (up|down or down|up). Or we can think of them as being in the triplet or singlet configuration. Is one description more correct than the other? Or is it just a matter of choice between two basis sets? It would seem to me that using T/S is correct because it accurately reflects the symmetry needed in the wavefunction. | 1 |
Find the distribution of U=min(X,Y) where X and Y are independent random variables and both exponentially distributed with parameters lambda and mu respectively. The only headway I have made is that P(U< u)= P(X< u)P(Y< u) by considering the joint distribution of X and Y and the fact X and Y are independent; is this right? If it is then U isn't a 'named' distribution function so is just stating the cdf enough to answer the question? | 1 |
I've noticed "At this stage" preceding delivery of the negative to the reader. What's the reason for this? "At this stage, unfortunately (for you), we won't be proceeding further with your application." "At this stage, your application has been declined." "At this stage, travel arrangements will be at your expense." This is used when there are no other stages. Why do people use this adverbial phrase? do you think it helps the reader to deal with emotional pain? | 1 |
In Thomas Harvey's Elementary Grammar and Compsition he says: A complex sentence whose subject or predicate only is a clause, need not be separated into principal and subordinate clauses in analysis. Later in the section he gives the example, "That he is very sick, is evident," parses the sentence, then gives a sentence diagram. I'm curious how one would break this sentence into its principal and subordinate clause. | 1 |
I am studying probabilites and the notion of poisson random variable was introduced in the class. But it seems to me that the introduction of poisson random variable is to provide a easy approximation of the binomial random variable conditioned that n is large and p is small. Besides, the preconditions in the poisson distribution that events are independent of each other seem to come from the fact that binomial random variable is composed by many independent bernouli variables. So I wonder if originally, poisson distribution was invented to model binomial distribution or was it invented to solve a particular kind of problem | 1 |
For some pdf ebooks, Adobe Reader displays the cover page alone even though the display mode is "two page view". Other than the cover page, the rest of the pdf content is displayed as two pages at once, which is expected in the "two page view" mode. My question is: Is it possible to enforce this behavior if I use pdflatex, and if so, how could I achieve that? The document class I'm using is memoir. | 1 |
In algebraic geometry, we often consider a complex algebraic curve, and in order to get some intuition, we often draw it on the plane as if it were a plane curve. In most cases it turns out that the plane drawing really helps us thinking of the curve for instance when counting the number of intersections. Then I wonder, to what extent the plane drawing is legitimate (or not misleading) to "represent" the complex algebraic curve? | 1 |
I have noticed that when certain tube-lights are switched 'ON' , they make certain noise corresponding to their "blinking". In blinking, there are alternate periods of the tube lighting up and then going out. The "sound" is heard at the instant the tube lights up. I can not properly describe the "noise" or the "sound" I'm referring to, but it seems as if the tube-light is struck gently with something. It feels as if the gas molecules inside the tube-light are striking its inner surface. Can anybody explain this ? | 1 |
In this question... Why does a photon colliding with an atomic nucleus cause pair production? ...I asked why a photon colliding with a atomic nucleus can become an electron and a positron. The answer that I thought was most illuminating explained that a photon spends some of its travel time as a particle-antiparticle pair of an electron and a positron. If it strikes the nucleus at the right time, this pair will be separated. It was explained that this is because 'Quantum Electrodynamics allows it'. Why does Quantum Electrodynamics allow a photon to exist temporarily as an electron and a positron? | 1 |
In batteries, what exactly do we mean by negative and positive charges? My understanding is that the negative charge of the anode is basically an atom with an extra electron in the last orbital and a minus electron in the last orbit of the positively charged atoms in the cathode? And so the electrons keep flowing and interchanging because the atom is trying to reach a stable state. Is this correct or am I wrong? If my understanding of positively/negatively charged atoms is correct, what do we mean by saying that the electron in itself has a negative charge? | 1 |
Most books on strongly correlated electrons claim that when the number of itinerant electrons is small and the screening length is large, that the system becomes "strongly correlated", (i.e. the independent electron approximation breaks down). If this is the case, why isn't doped silicon (or some other semiconductor/insulator) a strongly correlated electron system at low temperature where there are no thermal carriers? What are the critical ingredients that make a system unwilling to abide by the independent electron approximation? | 1 |
I am trying to draw an activation stack. I am really bat at TikZ, so I hope you can help me out. As you can see, there are four boxes stacked one on top of the other. Each box has a name, put on the right, and is made of an upper part, where variables and numbers are displayed, and a lower part which is divided in two halves. The left half has to contain an arrow pointing to one of the boxes placed under it, the right half contains only a few characters. The box at the bottom hdoesn't have a pointy arrow, because it doesn't have to reference anything. I really hope you can help me out, I really appreciate it. | 1 |
A lot of textbooks and exam boards claim that light incident at exactly the critical angle is transmitted along the media boundary (i.e. at right-angles to the normal), but this seems to violate the principle of reversibility in classical physics. How would a photon or ray travelling in the reverse direction "know" when to enter the higher refracting medium? It can't know, so I conclude that such light is simply reflected? Is this correct? | 1 |
My question is regarding effect of Sun's gravity on earth. I want to know that if Sun's gravity can change Earth's landscape in long duration (i.e. billion of years) or not? Means if earth is dead planet and all other planets are not present in the solar system and Earth is as near as Sun as mercury currently orbiting. And also suppose Earth's surface is not smooth (because of hitting with other small bodies at regular interval) then can Earth's surface can be smooth in long duration by gravity of Sun or not? | 1 |
Let A and E be opposite vertices of an octagon. A frog starts at vertex A. From any vertex except E it jumps to one of the two adjacent vertices. When it reaches E it stops. Let a(n) be the number of distinct paths of exactly n jumps ending at E. Find a(n) Is it right if I conclude that number of steps has to be an even number ? Also I don't know how to go further with that except I think recursion is involved. P.S. I'm having trouble solving questions in probability and combinatorics where recursions are involved like finding expected value ones. Can you provide me suggest me some links/books through which I can understand it better. Thanks | 1 |
I have a question that I am just curious about. Two principles: Magnetic fields and Magnetic susceptibility Supercavitation is the use of cavitation effects to create a bubble of gas inside a liquid large enough to encompass an object traveling through the liquid, greatly reducing the skin friction drag on the object and enabling achievement of very high speeds. Can a magnetic field hold a state of supercavitation if a magnetic field could be placed inside of the bubble of the supercavitation? | 1 |
Some people love creating or fostering the creation of events that are noisy, chaotic and fun, such as parties, arguments, reunions, etc. Sometimes there's a negative connotation to this (like in provoking an argument), but sometimes there is not (like in organising a big, noisy party). The word I'm looking for would be the English equivalent to the Spanish armadanzas, just in case this is helpful. Any ideas? | 1 |
Earlier, I asked here whether one can have spontaneous breaking of the Lorentz symmetry and was shown a Lorentz invariant term that can drive the vacuum to not be Lorentz invariant. How relaxed are the assumptions in the CPT theorem? Can one have the theorem to be valid for a Lorentz invariant theory with a vacuum that breaks it? Can someone point me to the original and alternate proofs of this theorem? Also, is there any connection between CPT invariance and renormalizability? | 1 |
Why is it said that electric current always flows from higher potential to lower potential? It's said that current flows from a positive terminal to a negative terminal, but I've read that it is actually the [negative] electrons that flow from the negative terminal to the positive one. Rather isn't it that the protons don't even move? My question here is in reference to electric circuits with batteries generally used in textbooks. | 1 |
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