Dataset Viewer
text
stringlengths 151
617k
| id
stringlengths 47
47
| metadata
dict |
|---|---|---|
This is a great activity that goes with the new book in the Sir Cumference series. The book is titled Sir Cumference and the Viking's Map. It is a story that correlates with coordinate graphing. The activity I made to go along with the book is a "map" graph and a set of ten sentences that have students mark an X at each of the stops (coordinate points). This is a great way to tie reading into your math lesson or math into a reading lesson.
|
<urn:uuid:7c98330a-5fcb-415a-b9ab-a628a7022b51>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-18T06:32:33",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368696381249/warc/CC-MAIN-20130516092621-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9690484404563904,
"score": 3.609375,
"token_count": 99,
"url": "http://www.teacherspayteachers.com/Product/Vikings-Map-Treasure-Hunt-209208"
}
|
What is Rainwater Harvesting?
Rainwater harvesting is an ancient practice of catching and holding rain for later use. In a rainwater harvesting system, rain is gathered from a building rooftop or other source and is held in large containers for future use, such as watering gardens or washing cars. This practice reduces the demand on water resources and is excellent during times of drought.
Why is it Important?
In addition to reducing the demand on our water sources (especially important during drought), rainwater harvesting also helps prevent water pollution. Surprised?
Here’s why: the success of the 1972 Clean Water Act has meant that the greatest threat to New York’s waterbodies comes not from industrial sources, but rather through the small actions we all make in our daily lives. For example, in a rain storm, the oil, pesticides, animal waste, and litter from our lawns, sidewalks, driveways, and streets are washed down into our sewers. This is called non-point source (NPS) pollution because the pollutants come from too many sources to be identified. Rainwater harvesting diverts water from becoming polluted stormwater; instead, this captured rainwater may be used to irrigate gardens near where it falls.
In New York City, keeping rainwater out of the sewer system is very important. That’s because the city has an old combined sewer system that uses the same pipes to transport both household waste and stormwater to sewage treatment plants. During heavy rains, the system overloads; then untreated sewage and contaminated stormwater overflow into our rivers and estuary, with serious consequences:
Who is Harvesting Rainwater in New York City?
Back in 2002, a drought emergency pushed many community gardens to the brink of extinction. For the first time in twenty years, community gardeners were denied permission to use fire hydrants, the primary source of water for most community gardens. This crisis led to the formation of the Water Resources Group (WRG), an open collaboration of community gardening and environmental organizations. With help from the WRG, rainwater harvesting systems have now been built as demonstration sites in twenty NYC community gardens.
At community gardens that harvest rainwater, rain is diverted from the gutters of adjacent buildings and is stored in tanks in the gardens. A 1-inch rainfall on a 1,000-square-foot roof produces 600 gallons of water. The tanks are mosquito proof, so the standing water does not encourage West Nile virus. Because rainwater is chlorine free, it is better than tap water for plant growth, meaning healthier plants. And it’s free!
What are Other Cities Doing?
Many cities have adopted creative, low-cost ways to stop wasting rainwater by diverting it from their sewage systems and putting it to use where it falls. Here are some examples:
What Can I Do?
Spread the word! Educate those around you on the importance of lifestyle decisions.
Tell people not to litter, dump oil down storm drains, or overfertilize their lawns.
Install a rainwater harvesting system at your home, school, business, or local community center.
Contact your local elected officials, and let them know you support rainwater harvesting!
Supporting rainwater harvesting Jade Boat Loans
|
<urn:uuid:14a860e9-8430-426b-8c1a-80c7f022fb96>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-18T05:02:32",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368696381249/warc/CC-MAIN-20130516092621-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9423009157180786,
"score": 3.890625,
"token_count": 671,
"url": "http://www.waterresourcesgroup.org/"
}
|
Marlin, Blue – Hawaii
Blue Marlin is a large pelagic species, found globally in both tropical and temperate waters. Blue Marlin mature early, produce many eggs , and grow fast, reaching sizes up to 450 cm and 900 kg.
They are caught commercially throughout the Pacific Ocean and are considered to comprise a single, ocean-wide population. The last population assessment for Blue Marlin in the Pacific indicated that abundance levels were moderate, but the assessment has not been updated for over a decade. There is some indication that Blue Marlin abundance around Hawaii may be declining.
This species is primarily captured with pelagic longlines, which result in minimal habitat damage and moderate bycatch rates. Around Hawaii, trolling is another common method used to catch Blue Marlin. Regulations for pelagic fisheries that capture Blue Marlin are set at both the international and national level, and include measures to effectively reduce fishery interactions with protected seabirds and sea turtles.
This fish may have high levels of mercury that could pose a health risk to adults and children. More mercury info here.
|
<urn:uuid:03621c9f-a97b-4bbb-9105-b90669a106d9>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-21T10:30:57",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368699881956/warc/CC-MAIN-20130516102441-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9423462748527527,
"score": 3.5625,
"token_count": 220,
"url": "http://blueocean.org/seafoods/marlin-blue-hawaii/?imgpage=2&showimg=423"
}
|
DUE: MONDAY MAY 13, 2013
As we have discussed in class, Elijah is surrounded by an aura of mystery: we know nothing of his parentage; his tribe of origin and birthplace are unknown (though he is identified as a “resident of Gilead”); we are ignorant about his early life and call to prophecy; he travels widely, performs miracles, and of greatest importance, defies a conventional death, ascending to heaven in a fiery chariot instead.
Approximately four centuries after Elijah’s strange prophetic career came to a close, the prophet Malachi believed he would return to earth to fulfill another divine mission: “Behold, I will send the prophet Elijah to you before the coming of the awesome, fearful day of the Lord. He shall reconcile parents with children, and children with their parents, so that, when I come, I do not strike the whole land with utter destruction” (Malachi 3:23-24).
Later on in rabbinic literature and folk legends, Elijah would take on a mythical role as the prophet who wanders the world generation after generation, protecting the weak and disadvantaged, humbling the arrogant who persecute the powerless. Capable of any disguise, he travels unrecognized through crowds of people, mysteriously appearing when needed and then just as mysteriously disappearing, revealing his identity on rare occasions only. It is fair to say that Elijah has captured the religious imagination of Jews as few other figures have.
The final project for 8th grade TaNaKh will focus on Elijah’s larger-than-life role in Jewish literature and liturgy. Choose ONE of the following. Please note the final project is in lieu of a final exam, and will count significantly toward your grade — along with other factors like participation, conduct, effort and attendance. Here are your choices:
1. Draw 3-4 pictures about Elijah, each telling a different story. You may wish to draw upon the biblical texts or folk stories we have studied (listed below) in creating your images. At least one of your pictures should place the prophet in a modern context. If Elijah came back today where would he go and whom would he visit? What would he look like? Each of your pictures should be accompanied by a paragraph or two explaining the setting and the reasons for depicting the prophet as you have.
2. Create a folktale about Elijah. While drawing upon the biblical texts and folk stories we studied in class for inspiration, your literary effort should be creative, and not a simple retelling of a traditional story. I would encourage you to read Elie Wiesel’s powerful short story, An Evening Guest (copies will be available from Cassie Vichozsky as of 4/22, and will also be distributed at our next class), which places Elijah in a small Hungarian town in 1944 as a messenger sent to warn Jews about the Nazi death camps — it’s a great example of taking the traditional picture of Elijah . . . and then turning it inside out in a very compelling way. Your folktale should be no shorter than 3 pages (typed, double-spaced, 12-font type).
3. Research references to Elijah in the siddur and on religious occasions. At what ceremonies and celebrations do we invoke his name? Where in our liturgy does he appear? When and how did Elijah become connected with these particular rituals/prayers? Why do we mention his name at these specific times/places? Your research paper should be 4 pages at a minimum (typed, double-spaced, 12-font type).
4. Elijah has also captured the religious imagination of Christians and Muslims. Research how Elijah is depicted in Christian and Muslim Scripture and compare/contrast this with the ways in which Judaism describes his role. What are the similarities and differences in the Jewish understanding of the prophet Elijah and the way the other Abrahamic faiths view him? Your research paper should be 4 pages at a minimum (typed, double-spaced, 12-font type).
We have studied the following sources about Elijah:
First Kings, chapters 17, 18 & 19; Second Kings, chapter 2; Folk stories about Elijah (handout distributed in class from Peninah Schram’s Jewish Stories One Generation Tells Another).
First Kings, chapter 21; Malachi, chapter 3; Elie Wiesel’s short story, An Evening Guest (available from Cassie as of 4/22).
|
<urn:uuid:76a4d786-85f5-491d-b1a9-489169361ccd>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-21T10:13:50",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368699881956/warc/CC-MAIN-20130516102441-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9461318850517273,
"score": 3.78125,
"token_count": 920,
"url": "http://mjgds.org/classrooms/lubliner/"
}
|
- HHMI NEWS
- SCIENTISTS & RESEARCH
- JANELIA FARM
- SCIENCE EDUCATION
- RESOURCES & PUBLICATIONS
noscripttags. Include a link to bypass the detection if you wish.
Investigate the specks, flecks, and particles in the air—with airborne junk detectors you can easily make. Directions are in this activity from HHMI’s Cool Science for Curious Kids.
Involve children in collecting leaves, rocks, and other natural items, and use the collections to teach children math and science skills. This resource from Oregon State University tells you what to do.
Use the insect fact sheet in this middle school curriculum from Clemson University to help children identify and classify insects they might find outdoors.
Taking a “virtual” field trip is almost as good as being outdoors. Explore a cove forest and a salt marsh with this program from Clemson University.
The HHMI Bulletin is now available for your iPad—inspiring stories, beautiful art, and MORE.
Read. Play. Listen.
Learn about the innovative work of biomedical researchers and science educators worldwide supported by the Howard Hughes Medical Institute.
Look for the FREE app in the iTunes App Store.
What Is Cool Science?
At Cool Science, we entertain questions of all kinds (Ask a Scientist). We encourage young scientists to get their hands dirty-virtually (Curious Kids). We offer high school and college students new approaches to cutting-edge science topics (BioInteractive). We provide educators with a host of innovative resources they can use in their classrooms (For Educators). We reveal what it takes to become a scientist (Becoming a Scientist). And we showcase an undergraduate science discovery project that may one day change the way science is taught (SEA).
We invite you to explore the many cool features of Cool Science.
Image: University of Washington
Help children study plants and animals in local outdoor settings by adapting some of the activities from this curriculum developed by Oregon State University.
Use these Yale University activities—which require simple, inexpensive, and easily obtainable materials—to help children learn about volcanoes, magnetism, and other topics.
When it’s too hot to be outdoors, educators, older students, and parents can try their hand at this visual and motor test that involves learning a new motor skill. This activity is from HHMI’s Biointeractive.
|
<urn:uuid:b8c4efe2-862f-4d2a-83e9-e788933d1e11>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-21T10:27:20",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368699881956/warc/CC-MAIN-20130516102441-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9024267792701721,
"score": 3.5625,
"token_count": 501,
"url": "http://www.hhmi.org/coolscience/?AxisPHP=9fb7a2c84a35100178d15b947a4d6b49"
}
|
An independent Republic of Armenia was proclaimed at the end of the 1914-1918 War but it lasted only until the beginning of the 1920s when the Bolsheviks incorporated it into the Soviet Union. Armenia's return to independence in 1991 was overshadowed by the conflict over Nagorno-Karabakh, the predominantly Armenian-populated region in Azerbaijan (see Current conflicts section). Full-scale war broke out the same year as ethnic Armenians in Karabakh fought for independence, supported by troops and resources from Armenia proper. A ceasefire in place since 1994 has failed to deliver any lasting solution.
Russia, France and the US co-chair the OSCE's Minsk Group, which has been attempting to broker an end to the dispute for over a decade. In 1997, the group tabled settlement proposals seen as a starting point for negotiations by Azerbaijan and Armenia but not by the de facto authorities in Nagorno-Karabakh itself. When the then-Armenian-president Levon Ter-Petrosyan tried to encourage Nagorno-Karabakh to enter into talks he was forced to resign amid cries of betrayal. Azerbaiijan declared illegitimate a referendum held in the region in December 2006.
Armenia's president Serzh Sarkisian and Azerbaijan's Ilham Aliyev agreed in November 2008 to intensify their efforts to find a political settlement to the dispute over Nagorno-Karabakh. They claimed to have made significant progress at talks in Prague in May 2009 on the sidelines of the EU's Eastern Partnership summit. This overview is based on the BBC online country profile for Armenia.
|
<urn:uuid:74189cbe-fd6d-4891-9872-ea41fb50a8b1>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-23T18:45:03",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368703682988/warc/CC-MAIN-20130516112802-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.957997739315033,
"score": 3.53125,
"token_count": 324,
"url": "http://www.geneva-academy.ch/RULAC/state.php?id_state=14"
}
|
Dangling Modifiers are words or phrases which “dangle” because they have no word in the sentence to describe:
While taking a shower, the doorbell rang.
--The doorbell was taking a shower?
Revise dangling modifiers by adding a headword—a noun or pronoun that is described:
While I was taking a shower, the doorbell rang. OR
While taking a shower, I heard the doorbell ring.
A Misplaced Modifier is placed too close to some other word that it does not intend to modify:
I only speak one language.
--All you ever do is speak one language?
Revise misplaced modifiers by placing the modifier next to its headword:
I speak only one language.
Split Infinitives are misplaced modifiers which are placed between the preposition to and the verb in an infinitive--a grammatical unit consisting of the word to plus a verb (to eat, to sleep, etc.):
Dentists encourage children to regularly brush their teeth.
--The modifier regularly is splitting the infinitive to brush.
Revise split infinitives by moving the modifier to another part of the sentence:
Dentists encourage children to brush their teeth regularly.
Squinting Modifiers are misplaced modifiers that seem to modify two words:
Patty who was walking quickly reached the disco.
--Is Patty walking quickly, or is she quickly reaching the disco?
Revise squinting modifiers by changing the word order so there is no ambiguity:
Patty, who was quickly walking, reached the disco.
OR Patty who was walking...
|
<urn:uuid:b7bbf796-459e-4dca-8d30-9bcfd6abd7c6>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-23T18:31:23",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368703682988/warc/CC-MAIN-20130516112802-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9437370896339417,
"score": 3.703125,
"token_count": 337,
"url": "http://www.uwf.edu/writelab/reviews/danglingandmisplaced2/"
}
|
SL Psychology/Intro to Research Methods
The following items should be included in this section: The Hypothetico-deductive (scientific)method, types of psychological research methods, research designs, sampling, reliability, validity, and triangulation.
Research into mind can be traced back to Ancient Greece. However, empirical psychological research has its roots in investigations into cognitive functions such as introspection and memory. While early psychological researchers attempted to bring the same standards of rigor and control to their investigations as physical scientists enjoy, psychological research poses unique obstacles. Psychological research investigates mind. Only recently the contents of the mind become observable since the advent of neuro-imaging technologies such as EEGs, PET scans, and fMRIs, thus early psychological research was focused on disagreements between different schools or generations of researchers that used varied approaches toward their investigations into the invisible mind. For example, cognitive researchers rely on inferences made from activities aimed at employing cognitive functions such as memory as opposed to examining how or where actual memories are laid down. Conversely Behaviorist researchers employed a more empirically rigorous method seeking only to make generalizations about phenomena that were directly observable and replicable in controlled settings.
Contemporary psychological research is derived from these disparate traditions and perspectives. It utilizes the hypothetico-deductive or scientific method:
1. observation and data gathering
2. inference of generalizations
3. construction of explanatory theories
4. deduction of hypothesis to test theories
5. hypothesis testing
6. support or challenges to existing theories and commensurate adjustments.
Theories and Hypothesis
Two key steps, theory construction and hypothesis deduction/testing pose special problems for researchers. Theories are sets of related generalizations explaining a specific mental phenomena e.g. schema and memory organization and hypotheses are specific predictions for research investigations. These steps are derived from empirical data, but are heavily influenced by an individual researcher’s perspective. Thus, researchers seek to clearly articulate operational definitions in an effort to make their research easily replicable. Additionally, controls are implemented to ensure credibility of results and subsequent conclusions. Finally, published research contributing to knowledge in the discipline is peer reviewed and usually rigorously scrutinized. Psychological research can take many forms ranging from: controlled laboratory true experiments (involving the manipulation of independent variables and controls for confounding variables) to field research (involving deliberate manipulation of independent variables in natural uncontrolled environments) to naturalistic/quasi experimental method (involving observation and analysis of independent variables changed by natural incidence). No matter which research method is employed, controls are carefully implemented to ensure the credibility of research. Key issues surrounding controls are: research design, sampling, reliability and validity.
The underlying structure of an investigation. It involves how psychologists use subjects/participants in their experiments. The three most common designs are:
1.Repeated Measures: using the same subjects in the experimental and control conditions
2.Independent Measures :using different subjects/participants in the experimental and control conditions
3. Matched Pairs :using different subjects/participants in the experimental and control conditions with each sample having similar characteristics.
The process of selecting participants/subjects to examine derived from a target population (a specified subpopulation of all humans). The results of a study are inferred from examination of the sample’s performance on a given measure, thus the sample is key in the line of reasoning from initial design to examination of results. Several methods can be employed when choosing a sample: random, stratified and convenience. Random sampling provides the best chance for the sample group to be representative of the target population. Stratified samples reflect similar proportions of various sub-groups within a sample. Convenience sampling involves choosing participants/subjects that are available at the time of data collection. Convenience samples do not control for possible biases that may within certain subgroups of a population and thus the results and conclusions from a convenience sample must be analyzed with caution and triangulated.
A study is reliable if it is replicable and the same results are achieved repeatedly. There are four types of reliability in regard to psychological study:
- Test-Retest Reliability (also called stability reliability)
- Interrater Reliability
- Parallel Forms Reliability
- Internal Consistency Reliability
To judge for reliability in this case, the test is administered two different times to the exact same or similar subjects. This judges for consistency of results across time, and to make sure the results were not affected by context of the time. Reliability is higher if the retest is close in chronological proximity to the original test.
Research psychologists tend to replicate older studies to generate theories or to amend findings to account for reliability. In attention for example, Treisman consistently retested findings to amend the attention models.
Two or more judges score the test. The scores are then compared to determine how much the two raters agree on the consistency on a rating system.
An example of interrater reliability would be that of teachers grading essays for an AP or IB exam. If a scale from 1 to 5 was used (where 1 is the worst and 5 is the best), and one teacher gave an essay a score of 2 and another gave a score of 5, then the reliability would be inconsistent. Through training, practice, and discussion, the individual raters can reach a consistent level of assessing an experiment, test, or result. Often, the raters are moderated by a higher rater who will assist in reaching consistency.
Parallel Forms Reliability
A large set of questions that are related to the same construct are generated and then divided into two sets. The two different sets are given to the same sample of people at the same time. Therefore, the two tests that study the same content are judged against each other for consistency.
An example would be a pretest-posttest, where the two groups would either receive form 1 or form 2, and in the posttest situation, the groups would be switched.
Internal Consistency Reliability
In this case, the tool is used as the tool to determine reliability. Thus would be a test situation in which the items on the test measure the same content. Often, questions can be strikingly similar, which shows that the test is also a measure for internal consistency reliability. Therefore, the similar questions should be answered in the same way. There are different ways to measure internal consistency reliability:
- Average Inter-item Correlation
- Average Itemtotal Correlation
- Split-Half Reliability
- Cronbach's Alpha (a)
Quantitative versus Qualitative Measures
Coolican, H. (2004). Research methods and statistics in Psychology. Cambridge University Press.
1. In what ways has new technology changed the science of psychology? Provide three examples.
2. How does the importance of validity and reliability change depending on the type of study?
3. In what ways will the different aspects of an experiment (sampling, methods, reliabilty, and validity) affect the results and conclusions of an psychology study?
|
<urn:uuid:defcc62e-94ff-4b7f-9ff7-845347fa405d>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-26T02:48:22",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368706499548/warc/CC-MAIN-20130516121459-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9305745363235474,
"score": 4.0625,
"token_count": 1445,
"url": "http://en.m.wikibooks.org/wiki/SL_Psychology/Intro_to_Research_Methods"
}
|
ROMAIN WACZIARG FINDS LINK BETWEEN GENETIC DISTANCE AND INCOME DIFFERENCES
Study provides new perspective on technology adoption
Why are some countries rich and others poor? Much has been written on this question from a historical perspective, says UCLA Anderson Associate Professor Romain Wacziarg. "Countries that were colonized and populated by Europeans are generally more economically developed than countries that were not colonized, or were colonized but not populated by Europeans," he says.
Wacziarg thought this might have to do with the links between developed countries and Northwestern Europe, where the Industrial Revolution originated. "In particular," he says, "with the fact that the colonizers who settled in these regions had been close to the industrial breakthroughs of the eighteenth and nineteenth centuries."
So Wacziarg and Enrico Spolaore of Tufts University began looking at the long term determinants of economic performance by countries -- measured by per-capita income. The main hypothesis of their study was that, if a country has a significant population that is genetically related to the population in the country where a major technological innovation took place, the country is more likely to adopt this technology and develop economically. The results are presented in a paper by Wacziarg and Spolaore entitled, "The Diffusion of Development."
"The idea is not about being European per se," says Wacziarg. "It's about being close to the source of innovation. Not just geographically close, but also genetically close. New Zealand and Australia are not geographically close to Europe, but they still got the industrial revolution sooner than Papua New Guinea in part because they were colonized by Europeans."
Genetic distance measures the time since two populations had common ancestors. Much like siblings are more closely related than cousins since they share parents rather than grandparents, if two populations split apart 2,000 years ago, they will be genetically closer than two populations that split apart 10,000 years ago.
The mechanism linking genetic distance to income differences can take a variety of forms. People who are genetically close are more likely to trust each other. Populations that are genetically close can also communicate more easily, understand each others' cultural norms and values, and adopt practices conducive to modern development -- such as rapid human capital accumulation, low fertility and better political institutions.
One unique thing about this study is the notion that traits that account for differences across populations are transmitted vertically, from generation to generation, more easily than horizontally from one population to another. Because of this, separation between populations is associated with a host of differences in skills, culture and language that are potential barriers to development.
"We needed a way to measure the distance between populations of different countries," says Wacziarg. It turned out that geneticists have identified genetic markers that enable them to distinguish populations. And since these markers evolve at a steady rate, it is possible to determine the length of time since two populations had a common ancestor. It's like a molecular clock, he says.
Genetic distance is based on blood samples. Enzymes and protein markers vary from one population to another. The measure of genetic distance is known as FST Genetic Distance. "It's what geneticists call the measure of heterozygosity, which summarizes how different your genes are," says Wacziarg.
In the study, Wacziarg and Spolaore found that genetic distance is significantly correlated with current per-capita income differences between countries, even controlling statistically for geographic distance and other differences such as climate and resources. The results hold for income differences measured around the world since the year 1500. Interestingly, genetic distance correlates with the current differences in income among European countries despite their close geographic proximity.
"It's really quite simple," says Wacziarg. "The more genetically related people are, the more they will communicate, trust each other, imitate each other and share ideas. Closely related populations will exchange practices, values, and modes of production that are conducive to economic development."
"What the paper does not argue," says Wacziarg, "is that a country will never develop if it is really far from the technological frontier. It ultimately might get it, but the time it will take is proportional to its genetic distance from the source of innovation."
The study suggests that anything that fosters the exchange of ideas between populations that are genetically distant might help overcome barriers to development. One example, says Wacziarg, was the migration of engineers from India to the Silicon Valley as the area became a hub for information technology. He notes that this certainly helped make India a leader in software and IT services.
"You can overcome some genetic distance by bringing people close," he says. Another reason for India's commercial success with IT, notes Wacziarg, is that the Indian population, particularly in North India, is actually quite genetically close to European populations. Indians also had the advantage of speaking English, a heritage of the history of British colonization. A population more genetically and culturally distant from Europe may not have fared as well.
Wacziarg admits that his study may not have immediate policy implications for poor countries. "There is an aspect of pessimism involved in any study that says a current economic situation has roots in deep history," he explains. "You can't change deep history. There is a notion that poverty results from extremely persistent forces that are very hard to change."
But he maintains that economic development remains possible for any population. "This study suggests that anything that facilitates the flow of ideas and exchange between distant populations might help," he says. "Countries do develop and become richer. India and China are cases in point."
Read more about the study in Economic Principles.
|
<urn:uuid:b925bb80-f92d-42af-9664-4f72219dfeed>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-18T17:28:43",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368696382584/warc/CC-MAIN-20130516092622-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9670978784561157,
"score": 3.546875,
"token_count": 1179,
"url": "http://www.anderson.ucla.edu/knowledge-assets/romain-wacziarg"
}
|
What Are the Six Common Air Pollutants?
The Clean Air Act requires EPA to set National Ambient Air Quality Standards for six common air pollutants. These commonly found air pollutants (also known as "criteria pollutants") are found all over the United States. They are particle pollution (often referred to as particulate matter), ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead. These pollutants can harm your health and the environment, and cause property damage. Of the six pollutants, particle pollution and ground-level ozone are the most widespread health threats. EPA calls these pollutants "criteria" air pollutants because it regulates them by developing human health-based and/or environmentally-based criteria (science-based guidelines) for setting permissible levels. The set of limits based on human health is called primary standards. Another set of limits intended to prevent environmental and property damage is called secondary standards.
Click on one of the pollutants below for information on sources of the pollutant, why the pollutant is of concern, health and environmental effects, efforts underway to help reduce the pollutant, and other helpful resources.
Air Pollution Trends
For each of these pollutants, EPA tracks two kinds of air pollution trends: air concentrations based on actual measurements of pollutant concentrations in the ambient (outside) air at selected monitoring sites throughout the country, and emissions based on engineering estimates of the total tons of pollutants released into the air each year. Despite the progress made in the last 30 years, millions of people live in counties with monitor data showing unhealthy air for one or more of the six common air pollutants. For EPA's most recent evaluation of air pollution trends for these six pollutants, click on the following:
Health Effects Information
Exposure to these pollutants is associated with numerous effects on human health, including increased respiratory symptoms, hospitalization for heart or lung diseases, and even premature death. Try these helpful resources:
- Air Quality Index (AQI)
- Ozone - Good Up High, Bad Nearby
- Ozone and Your Health
- Particle Pollution and Your Health
- Air Quality Guide for Ozone
- Air Quality Guide for Particle Pollution
- Smog - Who Does it Hurt?
State Implementation Plan Status and Information
EPA must designate areas as meeting (attainment) or not meeting (nonattainment) the standard. The Clean Air Act (CAA) requires states to develop a general plan to attain and maintain the NAAQS in all areas of the country and a specific plan to attain the standards for each area designated nonattainment for a NAAQS. These plans, known as State Implementation Plans or SIPs, are developed by state and local air quality management agencies and submitted to EPA for approval. Detailed information about state SIP elements and their status can be found on the State Implementation Plan Status and Information page.
|
<urn:uuid:392da6cd-35e6-45f0-8e63-2e7df07dbdc6>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-18T18:01:38",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368696382584/warc/CC-MAIN-20130516092622-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9092231392860413,
"score": 3.796875,
"token_count": 592,
"url": "http://www.epa.gov/oaqps001/urbanair/"
}
|
| ||Minding Your Mind || |
Psychiatric Treatment for Preschoolers
Last reviewed and revised on June 17, 2011
By Michael Craig Miller, M.D.
Harvard Medical School
The number of medications prescribed to children ages two to four to treat psychiatric disorders increased dramatically after the early 1990s.
A Delicate Balance
As any parent can attest, the preschool years are a time of tremendous brain development. Between the ages of two and five, children learn to talk, develop hand and eye coordination, and learn how to interact with others.
Brain changes underlie these developments. The number of synapses (connections between brain cells) and neurotransmitter receptors reach their peak at age three, while the brain's metabolic rate peaks between ages three and four.
Clinicians and parents thus face a delicate balancing act when it comes to treating psychiatric disorders, especially in the youngest children. There are risks associated with giving medications, because we don't know exactly what effects psychiatric drugs may have on the developing brain. But there can also be significant risk from not giving medications, because mental disorders also have a negative effect on brain development.
Mental disorders can lead to impaired peer and family relationships and poor school performance. Untreated childhood problems may give way to continuing mental health problems when the child when he or she grows up. And there is evidence that many lifelong psychiatric disorders begin early. A Harvard study published in 2005 estimated that half of all disorders that meet standard criteria for a diagnosis start by age 14.
There is no simple way to tell normal variations in temperament or development from the beginnings of a mental health problem. In practical terms, a child's problems may require medication to ease suffering and help him or her develop normally. Medications may be worth trying especially if non-drug treatments haven't been effective. But it is worth emphasizing that these decisions are almost always very difficult to make in the youngest children.
Back to top
Guidance for Three Disorders
Attention deficit hyperactivity disorder
Experts recommend a thorough evaluation to define the problem. This requires reports from parents, teachers and child care providers so that the clinician can assess the child's symptoms in multiple settings. Parents can be taught the best ways to help their children. Whether a child needs medication or not, he or she will probably do better if the parents become comfortable with skills for setting limits and rewarding positive behavior. If parent guidance and psychotherapy are not sufficient to control symptoms, a trial of methylphenidate (Ritalin) or another related drug for six months may be considered. After six months, the doctor can stop the medication to see if the child still needs it, either for controlling symptoms or improving functioning in school. Numerous other medications are available if methylphenidate does not work.
Anxiety disorders (separation anxiety, selective mutism, specific phobia)
In addition to making their own observations, clinicians will have an easier time defining the problem if they can get information from parents, teachers and other caregivers. Sometimes formal rating scales and questionnaires are used during the evaluation. The clinician should also remain alert to co-existing problems, like depression or behavior problems. Available research suggests that psychotherapy may teach a child to better control behavior while also improving self-esteem. So, a course of at least 12 weeks is usually the first intervention to try. If psychotherapy does not provide relief and anxiety symptoms continue to impair the child's functioning, a low dose of fluoxetine (Prozac) or a similar drug can be considered. After six to nine months, the clinician may be able to taper and then stop medication.
Developmental disorders, such as Autism
These children should have formal intelligence tests, plus tests of hearing and language skills. Useful evaluation instruments are the Childhood Autism Rating Scale and the Aberrant Behavior Checklist. Before thinking about medication, a team of helpers may be necessary to coach a child to improve language skills, enhance social development, and reduce repetitive behavior and aggression. Medication may eventually be necessary for children who have severe behavioral problems that interfere with functioning. As with anxiety disorders, the clinician can assess if medication is still needed after six to nine months.
Back to top
Maximize Help and Minimize Harm
Here are some useful principles to guide the evaluation and treatment of any problem that comes up in a young child.
- Address diagnostic challenges. Preschoolers vary in terms of development, personality, and communication skills. Diagnostic criteria for adults and older children may not be relevant to preschoolers. When possible, a diagnosis should be made after several visits with the child and only after multiple sources have provided information about the child's progress (the child, parents, teachers, other clinicians).
- Track symptoms and impairment. Before starting any treatment, the clinician and family should work together to define symptoms and any functional impairment, so these can be tracked over time. This will help in assessing whether a particular treatment is working.
- Try psychotherapy first. Various types of psychological interventions are worth trying first, and for a sufficient time, before adding a medication to the mix.
- Once medication has been started, monitor the response. If a child's symptoms do not improve after trying medication, stop the medication. Even when a medication works, plan on discontinuing it for a time to see if the drug is still necessary. (A child's ongoing brain development may correct the underlying problem.) Avoid adding medications to alleviate side effects of other medications.
- Clinicians should invite parents to stay involved. Parents are important partners in care. If parents need help in handling stress, learning better parenting skills or dealing with their own mental health issues, they should be referred to an appropriate practitioner.
When a child has significant mental or behavior trouble, it places a strain on them, the parents, siblings and classmates. Basic principles don't necessarily make life easy. But taking a systematic approach will improve the chances your child will avoid unnecessary troubles, and have the best chance to get needed help.
Back to top
Michael Craig Miller, M.D. is editor-in-chief of the Harvard Mental Health Letter and an assistant professor of psychiatry at Harvard Medical School. Dr. Miller has an active clinical practice and has been on staff at Beth Israel Deaconess Medical Center for more than 25 years.
|
<urn:uuid:53bdaba2-de2b-4610-a413-6dd7a7d2ebc6>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-18T18:08:24",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368696382584/warc/CC-MAIN-20130516092622-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9234449863433838,
"score": 3.515625,
"token_count": 1289,
"url": "http://www.intelihealth.com/IH/ihtIH/EMIHC256/35320/63153/808693.html?d=dmtHMSContent"
}
|
Jan. 31, 2008 Drugs derived from cinchona bark, known as cinchona alkaloids, have been used in healing from ancient times. The most prominent representative of this group is quinine, a bitter substance contained in beverages such as tonic water and used in modern medicine to combat malaria. As early as 1945, Robert Burns Woodward and William von Eggers Doering (Harvard University) described how to synthesize quinine in the laboratory.
The last step of this “formal” total synthesis, a three-step reaction procedure previously described by Paul Rabe and Karl Kindler in 1918, has continued to be the subject of much controversy to this day. Aaron C. Smith and Robert M. Williams at Colorado State University (USA) have now successfully reproduced the Rabe–Kindler protocol. As described in an Angewandte Chemie article dedicated to Doering on his 90th birthday, they repeated the entire procedure without employing any modern methods.
Had they done it or not? That has been the question for decades. Woodward and Doering published the synthesis of d-quinotoxine in 1944. Based on the conversion of d-quinotoxine into quinine described by Rabe and Kindler in 1918, they claimed to have derived the total synthesis of quinine, though they had not actually completed this last step themselves before publishing. Their “formal” total synthesis was strongly challenged and was even dismissed as a “myth” by Gilbert Stork (Columbia University) in 2001.
“Quinine and the cinchona bark alkaloids play an important role in modern medicine. It is thus amazing that no attempts to reproduce the Rabe–Kindler conversion of quinotoxine into quinine have been published,” marvels Williams. Smith and Williams reviewed the old publications, researched further references, and set themselves the task of repeating the procedure outlined by Rabe and Kindler—and with techniques available at the time. Initially, the yield of quinine they obtained was far too low.
The key turned out to be the aluminum powder used as a reducing agent in the last step. It must not be too fresh, instead it must be exposed to air for a while first to produce a small amount of aluminum oxide. This results in yields of quinine in agreement with those in the old publications.
“Analytically pure quinine can be isolated from this reaction by the selective crystallization of the corresponding tartrate salt, just as described by Rabe in 1939,” says Williams. “We have thus corroborated Rabe and Kindler’s 1918 publication. Woodward and Doering could theoretically also have followed this procedure in 1944.”
Journal article: Rabe Rest in Peace: Confirmation of the Rabe-Kindler Conversion of d-Quinotoxine to Quinine: Experimental Affirmation of the Woodward-Doering Formal Total Synthesis of Quinine. Angewandte Chemie International Edition , doi: 10.1002/anie.200705421
Other social bookmarking and sharing tools:
Note: If no author is given, the source is cited instead.
|
<urn:uuid:285b9d18-aee2-405d-8def-480b6bd6a04e>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-18T18:10:04",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368696382584/warc/CC-MAIN-20130516092622-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9398418068885803,
"score": 3.53125,
"token_count": 669,
"url": "http://www.sciencedaily.com/releases/2008/01/080131111817.htm"
}
|
A depressive disorder is a whole-body illness, involving the body, mood, and thoughts, and affects the way a person eats and sleeps, feels about himself or herself, and thinks about things. It is not the same as being unhappy or in a blue mood. Nor is it a sign of personal weakness or a condition that can be willed or wished away. People with a depressive illness cannot merely "pull themselves together" and get better.
Without treatment, symptoms can last for weeks, months, or years. Appropriate treatment, however, can help most people who suffer from depression. During any one year period, nearly 19 million American adults suffer from depressive illness. Yet, treatment can alleviate symptoms in nearly 80 percent of cases.
Women experience depression about twice as often as men. Many hormonal factors may contribute to the increased rate of depression in women--particularly such factors as menstrual cycle changes, premenstrual syndrome (PMS), pregnancy, miscarriage, postpartum period, perimenopause, and menopause. Many women also face additional stresses such as responsibilities both at work and home, single parenthood, and caring for children and aging parents.
Many women are also particularly vulnerable after the birth of a baby. The hormonal and physical changes, as well as the added responsibility of a new life, can be factors that lead to postpartum depression in some women. While transient "blues" are common in new mothers, a full-blown depressive episode is not a normal occurrence and requires active intervention. Treatment by a sympathetic health care provider and the family's emotional support for the new mother are prime considerations in aiding her to recover her physical and mental well-being and her ability to care for and enjoy the infant.
Depressive disorders come in different forms, as do other illnesses, such as heart disease. Three of the most prevalent types of depressive disorders include the following:
- Major depression. A combination of symptoms (see symptom list) that interfere with the ability to work, sleep, eat, and enjoy once pleasurable activities. These disabling episodes of depression can occur once, twice, or several times in a lifetime.
- Dysthymia. Long-term, chronic symptoms that do not disable, but keep people from functioning at "full steam" or from feeling good. Sometimes, people with dysthymia also experience major depressive episodes.
- Bipolar disorder (manic-depression). A chronic, recurring condition that includes cycles of depression and elation or mania.
Within these types, there are variations in the number of symptoms, their severity, and persistence.
The following are the most common symptoms of depression. However, each individual may experience symptoms differently. In general, nearly everyone suffering from depression has ongoing feelings of sadness, and may feel helpless, hopeless, and irritable.
The American Psychiatric Association suggests that professional help is advisable for those who have four or more of the following symptoms continually for more than two weeks:
- Noticeable change of appetite, with either significant weight loss not attributable to dieting or weight gain
- Noticeable change in sleeping patterns, such as fitful sleep, inability to sleep, early morning awakening, or sleeping too much
- Loss of interest and pleasure in activities formerly enjoyed
- Persistent sad, anxious, or "empty" mood
- Feelings of hopelessness, pessimism
- Restlessness, irritability
- Decreased energy, fatigue, being "slowed down"
- Feelings of worthlessness
- Persistent feelings of hopelessness
- Feelings of inappropriate guilt
- Inability to concentrate or think, indecisiveness
- Recurring thoughts of death or suicide, wishing to die, or attempting suicide (Note: Individuals with this symptom should receive treatment immediately!)
- Melancholia (defined as overwhelming feelings of sadness and grief), accompanied by the following:
- Waking at least two hours earlier than normal in the morning
- Feeling more depressed in the morning
- Moving significantly more slowly
- Disturbed thinking--for example, severely depressed people sometimes have beliefs not based in reality about physical disease, sinfulness, or poverty
- Physical symptoms, such as headaches, digestive disorders, and chronic pain
Specific treatment for depression will be determined by your health care provider based on:
- Your age, overall health, and medical history
- Extent of the depression
- Your tolerance for specific medications, procedures, or therapies
- Expectations for the course of the disorder
- Your opinion or preference
Generally, based on the outcome of evaluations, depressive disorders are treated with medication or either psychotherapy or cognitive behavioral therapy, or a combination of medication and therapy.
You can also help yourself. Depressive disorders can make a person feel exhausted, worthless, helpless, and hopeless. Such negative thoughts and feelings make some people feel like giving up. It is important to realize that these negative views are part of the depression and typically do not accurately reflect the actual circumstances. Negative thinking fades as treatment begins to take effect. In the meantime, consider the following:
- Set realistic goals in light of the depression and assume a reasonable amount of responsibility.
- Break large tasks into small ones, set some priorities, and do what you can as you can.
- Try to be with other people and to confide in someone; it is usually better than being alone and secretive.
- Participate in activities that may make you feel better.
- Mild exercise, going to a movie, a ball game, or participating in religious, social, or other activities may help.
- Expect your mood to improve gradually, not immediately. Feeling better takes time.
- It is advisable to postpone important decisions until the depression has lifted. Before deciding to make a significant transition--change jobs, get married or divorced--discuss it with others who know you well and have a more objective view of your situation.
- People rarely "snap out of" a depression. But they can feel a little better day-by-day.
- Remember, positive thinking will replace the negative thinking that is part of the depression and will disappear as your depression responds to treatment.
- Let your family and friends help you.
Click here to view the
Online Resources of Women's Health
|
<urn:uuid:f005b074-a9cf-4354-a1ab-15ec7db4b733>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-21T17:25:05",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368700264179/warc/CC-MAIN-20130516103104-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9449301958084106,
"score": 3.765625,
"token_count": 1284,
"url": "http://www.muschealth.com/gs/HealthTopic.aspx?action=showTopic&pageid=P01512"
}
|
In the muted light of an open doorway and a rosette window, two Jewish men are shown walking through the entry porch of the Regensburg synagogue. Altdorfer made two etchings of the temple just before it was destroyed on February 22, 1519: this view and one of the interior nave. Emperor Maximilian had long been a protector of the Jews in the imperial cities, extracting from them substantial taxes in exchange. Within weeks of his death, however, the city of Regensburg, which blamed its economic troubles on its prosperous Jewish community, expelled the Jews. Altdorfer, a member of the Outer Council, was one of those chosen to inform the Jews that they had two hours to empty out the synagogue and five days to leave the city. The date of the demolition inscribed at the top of the print suggests that Altdorfer made the preparatory sketches, as well as the etchings themselves, with the knowledge that the building was to be destroyed. The prints appear to have been quickly produced, quite possibly during the five days prior to the temple's destruction: the plate was not evenly etched, particularly in the areas of dense hatching, where the individual lines lose clarity. In addition, the slightly tipsy vaults appear to have been traced freehand rather than with a compass. Despite the seemingly sensitive portrayal, the print was not intended as a sympathetic rendering of an aspect of Jewish culture, but rather as a much more dispassionate recording of the site. It is thus the first portrait of an actual architectural monument in European printmaking.
|
<urn:uuid:0c7c4a72-4a4d-4d1b-a40c-c6ea93bcc2f1>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-24T01:51:20",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704132298/warc/CC-MAIN-20130516113532-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9797773361206055,
"score": 4.03125,
"token_count": 323,
"url": "http://metmuseum.org/Collections/search-the-collections/90003246?high=on&rpp=15&pg=1&rndkey=20120723&ft=*&who=Albrecht+Altdorfer&pos=1"
}
|
New Granada (grənäˈdə) [key], former Spanish colony, N South America. It included at its greatest extent present Colombia, Ecuador, Panama, and Venezuela. Between 1499 and 1510 a host of conquerors explored the Caribbean coast of Panama and South America. After 1514, Pedro Arias de Ávila was successful in assuring permanent colonization of the isthmus of Panama. At Santa Marta (1525) and Cartagena (1533), Spanish control of the Colombian coast was firmly established, and in the next few years the northern hinterland was explored. German adventurers, notably Nikolaus Federmann, penetrated the Venezuelan and Colombian llanos between 1530 and 1546. By far the greatest of the conquerors was Gonzalo Jiménez de Quesada, who in 1536 ascended the Magdalena River, climbed the mighty Andean cordillera, where he subdued the powerful Chibcha (an advanced native civilization), and by 1538 had founded Santa Fé de Bogotá, later known simply as Bogotá. He named the region El Nuevo Reino de Granada [the new kingdom of Granada]. During the next 10 years the conquest was virtually completed. No civil government was established in New Granada until 1549, when an audiencia court, a body with both executive and judicial authority, was set up in Bogotá. To further stabilize colonial government, New Granada was made a presidency (an administrative and political division headed by a governor) in 1564, and the audiencia was relegated to its proper judicial functions. Loosely attached to the viceroyalty of Peru, the presidency came to include Panama, Venezuela, and most of Colombia. Disputes with—and the great distance from—Lima led to the creation (1717) of the viceroyalty of New Granada, comprising Colombia, Ecuador, Panama, and Venezuela. Later the captaincy general of Venezuela and the presidency of Quito were detached, creating a political division that was to survive the revolution against Spain and the efforts of Simón Bolívar to establish a republic of Greater Colombia. The struggle for independence began in 1810, and by 1830 Venezuela and Ecuador had seceded, and the remnant (Colombia and Panama) was renamed the Republic of New Granada. This became the Republic of Colombia in 1886, from which the present Panama seceded in 1903.
See A. J. Kuethe, Military Reform and Society in New Granada (1978).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
More on New Granada from Fact Monster:
See more Encyclopedia articles on: Latin American History
|
<urn:uuid:1872d9f4-aa67-47f8-b483-01fe0f93cd28>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-24T02:08:43",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704132298/warc/CC-MAIN-20130516113532-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9361494779586792,
"score": 4.03125,
"token_count": 573,
"url": "http://www.factmonster.com/encyclopedia/history/new-granada.html"
}
|
|Bailey's Ecoregions and Subregions of the
United States, Puerto Rico, and the U.S. Virgin Islands
What this map layer shows:
Ecoregions defined by common climatic and vegetation characteristics,
shown as domains, divisions, provinces and sections.
Ecoregions are ecosystems of regional extent. Bailey's ecoregions distinguish
areas that share common climatic and vegetation characteristics. A
four-level hierarchy is used to differentiate the ecoregions, with the
broadest classification being the domain. Domains are groups of related
climates and are differentiated based on precipitation and temperature.
There are four domains used for worldwide ecoregion classification and
all four appear in the United States: the polar domain, the humid temperate
domain, the dry domain, and the humid tropical domain. Divisions represent
the climates within domains and are differentiated based on precipitation
levels and patterns as well as temperature. Divisions are subdivided
into provinces, which are differentiated based on vegetation or other
natural land covers. Mountainous areas that exhibit different ecological
zones based on elevation are identified at the province level. The
finest level of detail is described by subregions, called sections,
which are subdivisions of provinces based on terrain features.
The purpose of ecological land classification is to provide information
for both the development of resources and the conservation of the environment.
Government and private land managers use this information to estimate
ecosystem productivity, to determine probable responses to land management
practices, and to address environmental issues over large areas, such
as air pollution, forest disease, or threats to biodiversity. This
map layer was compiled by the USDA
The Bailey's Ecoregions and Subregions of the United States, Puerto
Rico, and the U.S. Virgin Islands map layer shows the ecoregion domains,
divisions, provinces, and sections for this area. Further information
on domains, divisions, and provinces is available from the USDA Forest
Service Rocky Mountain Research Station page describing Ecoregions
of the United States, and detailed information on sections is available
through the USDA Forest Service page, Ecological
Subregions of the United States.
The National Atlas also includes a map layer showing Omernik's
Level III Ecoregions, which are defined by a wide variety of characteristics,
including vegetation, animal life, geology, soils, water, climate,
and human land use, as well as other living and non-living ecosystem components.
|
<urn:uuid:5e0305d0-788d-465d-9c1a-318233c38eba>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-24T01:29:49",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704132298/warc/CC-MAIN-20130516113532-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.8892916440963745,
"score": 3.609375,
"token_count": 536,
"url": "http://www.nationalatlas.gov/mld/ecoregp.html"
}
|
The fish family that includes herrings, shads, sardines, and menhadens is a large, global family with 216 species. Most species are tropical and almost all species are found in oceans, although some are found in freshwater as well. Fish in this family are small to medium-sized, from 2 to 75 cm long. They generally have torpedo shaped bodies that are laterally compressed. Fish in this family are strong, fast swimmers, generally travel in large schools, and they typically feed on plankton. They are some of the most important commercially fished species in the world.
Tanya Dewey (author), Animal Diversity Web.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
having the capacity to move from one place to another.
specialized for swimming
uses touch to communicate
|
<urn:uuid:46837a76-440f-4330-bdb5-3e64616954c2>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-26T09:37:10",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368706890813/warc/CC-MAIN-20130516122130-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9631431698799133,
"score": 3.59375,
"token_count": 214,
"url": "http://animaldiversity.ummz.umich.edu/accounts/Clupeidae/"
}
|
Build any Major Scale
Building A Major Scale
Just like with building triads, building a major scale is about understanding the intervals between each note of the scale. If you understand this, you can build any major scale.
All major scales follow this pattern:
(W = Whole Step, H = Half Step)
W - W - H - W - W - W - H
So let's look at the notes of a C major scale. They are shown below with the interval between each note in parenthesis:
C (W) D (W) E (H) F (W) G (W) A (W) B (H) C
A good way to practice is to just pick a random note on the keyboard and then build your major scale. Learning your scales this way will make sure you don't ever forget the notes in a major scale.
|
<urn:uuid:56e50ba9-4f66-43e2-bddb-c05ffccaab1b>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-26T09:35:13",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368706890813/warc/CC-MAIN-20130516122130-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9048723578453064,
"score": 3.5625,
"token_count": 180,
"url": "http://www.lessonrating.com/free-piano-lessons-major-scales.html"
}
|
Pub. date: 2010 | Online Pub. Date: May 06, 2010 | DOI: 10.4135/9781412958660 | Print ISBN: 9781412958653 | Online ISBN: 9781412958660| Publisher:SAGE Publications, Inc.About this encyclopedia
Property is a general term for things such as land or other material resources and goods, the relations between people and those things, the relations between people with respect to those things, or the system of rules that governs these relations. Every society with an interest in avoiding conflict between people over things requires such a system; without it, a civilized common life is impossible. We may distinguish three ideal types of systems that could be used to organize property in a society. Under the first type of system, property is held in common, and all members of the society are free to use it as they choose without spoiling it for others. Under the second type of system, property is held collectively, and society collectively determines its use. Under the third type of system, property is held privately, and those who hold it are free to use it In ...
|
<urn:uuid:ccd5b8f1-22f5-4dcf-b9bd-ed2cb608ba2f>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-19T02:32:52",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368696383156/warc/CC-MAIN-20130516092623-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9332727193832397,
"score": 3.640625,
"token_count": 227,
"url": "http://knowledge.sagepub.com/abstract/politicaltheory/n362.xml"
}
|
Animal Species:Striped Dolphin
The Striped Dolphin is a small sleek compact dolphin with a striking body pattern that gives it its name.
The Striped Dolphin is a small sleek compact dolphin with a long well defined beak, prominent dorsal fin and short tapering flippers. It is the striking body pattern that gives it its name. A bold black stripe runs the full length of the body from behind the eye to the anus. This separates the bluish grey flank from the white ventral surface. A second smaller stripe runs from the front of the eye to the behind the flipper. A third section of dark grey covers the top of the head, the dorsal fin and on towards the back of the body.
The distribution of the Striped Dolphin is confined to warm tropical and temperate waters, where it occurs in schools of many hundreds of animals. These groups are highly visible as they stir the surface with displays of high speed swimming and aerial acrobatics.
Feeding and Diet
A widely distributed species such as this tends to include a high diversity of organisms in its diet. These include a variety of shoaling fish and cephalopods (squid and octopus) concentrating on those species occurring in large dense schools.
These animals form very socially cohesive groups of between 100 and 500 individuals however the age structure varies. Some are composed of adults only, others consist of adults and juveniles. Calving occurs in late summer in smaller mixed aged schools numbering about 30 animals. The gestation period lasts about one year with the interval between such events around of four years.
The Striped Dolphin is an abundant species. It has had some regional population losses such as those stemming from the drive fisheries practiced in Japan, and the mysterious die off of more than 1000 individuals in the Mediterranean. Fishing industry practices still cause some deaths through entanglement and indirectly impact on some populations by depletion of their food resource.
- Baker, A. N. 1999. Whales and Dolphins of Australia and New Zealand: an identification guide. Allen & Unwin, St Leonards, Australia.
- Bryden, M., Marsh, H. and Shaughnessy, P. 1998. Dugongs, Whales, Dolphins and Seals. A guide to the sea mammals of Australasia. Allen & Unwin, St Leonards, Australia.
- Menkhorst, P. 2001. A Field Guide to Mammals of Australia. Oxford University Press, Melbourne, Australia.
- Reeves, R. R., Stewart, B. S., Clapham, P. J. and Powell, J. A. 2002. National Audubon Society Guide to Marine Mammals of the World. Chanticleer Press, Inc New York, USA.
|
<urn:uuid:aafa8009-727c-4bcd-bc6b-ca2e7916c893>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-19T02:33:35",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368696383156/warc/CC-MAIN-20130516092623-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.8807941675186157,
"score": 3.640625,
"token_count": 560,
"url": "http://www.australianmuseum.net.au/Striped-Dolphin"
}
|
B2: A mixture of 2% biodiesel and 98% petroleum diesel based on volume.
B20: A mixture of 20% biodiesel and 80% petroleum diesel based on volume.
B100: 100% biodiesel, also known as “neat” biodiesel.
BIODIESEL: A biodegradable transportation fuel for use in diesel engines that is produced through the transesterfication of organically-derived oils or fats. It may be used either as a replacement for or as a component of diesel fuel.
CARBON DIOXIDE (CO2): A colorless, odorless gas produced by respiration and combustion of carbon-containing fuels. Plants use it as a food.
E10: A mixture of 10% ethanol and 90% gasoline based on volume.
E85: A mixture of 85% ethanol and 15% gasoline based on volume.
ETHANOL (CH3CH2OH): A colorless, flammable liquid produced by fermentation of sugars. Used as a fuel oxygenate and found in alcoholic beverages.
FERMENTATION: A biochemical reaction that breaks down complex organic molecules (such as carbohydrates) into simpler materials (such as ethanol, carbon dioxide and water). Bacteria or yeasts can ferment sugars to ethanol.
GLYCERIN (C3H8O3): A liquid by-product of biodiesel production. Glycerin is used in the manufacture of dynamite, cosmetics, liquid soaps, inks and lubricants.
HYDROCARBON (HC): An organic compound that contains only hydrogen and carbon. In vehicle emissions, these are usually vapors created from incomplete combustion or from vaporization of liquid gasoline. Emissions of hydrocarbons contribute to ground level ozone.
METHYL-TERTIARY BUTYL ESTER (MTBE): A fuel oxygenate made from petroleum. It does not biodegrade and can contaminate groundwater.
NITROGEN OXIDES (NOx): A product of photochemical reactions of nitric oxide in ambient air, and the major component of photochemical smog.
OXYGENATE: A compound which contains oxygen in its molecular structure. Ethanol and biodiesel act as oxygenates when they are blended with conventional fuels. Oxygenated fuel improves combustion efficiency and reduces tailpipe emissions of CO.
OZONE: A compound that is formed when oxygen and other compounds react in sunlight. In the upper atmosphere, ozone protects the earth from the sun's ultraviolet rays. Though beneficial in the upper atmosphere, at ground level, ozone is called photochemical smog, and is a respiratory irritant and considered a pollutant.
PARTICULATES: A fine liquid or solid particle such as dust, smoke, fumes, or smog, found in air or emissions.
PETROLEUM: Any petroleum-based substance comprising a complex blend of hydrocarbons derived from crude oil through the process of separation, conversion, upgrading, and finishing, including motor fuel, jet oil, lubricants, petroleum solvents, and used oil.
SULFUR: A natural part of petroleum diesel fuel that is reduced during refining due to an EPA mandate. Sulfur increases petroleum diesel's lubricity and therefore engine life. Sulfur oxides and sulfides in exhaust emissions are major components of acid rain.
TRANSESTERFICATION: A chemical process which reacts an alcohol with the triglycerides contained in vegetable oils and animal fats to produce biodiesel and glycerin.
Source: Department of Energy, National Biodiesel Board and Renewable Fuels Association.
Information At Your Fingertips
Industry association Web sites are primed with information on biodiesel and ethanol. Visit the following sites to learn more on both topics, including locations on where to purchase biodiesel in your area:
|
<urn:uuid:775fb6ea-8f45-4dc4-bb85-b879b77053ff>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-22T00:32:01",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368700958435/warc/CC-MAIN-20130516104238-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.913179874420166,
"score": 3.5,
"token_count": 796,
"url": "http://cornandsoybeandigest.com/print/biofuels-defined"
}
|
The shortgrass prairie ecosystem of the North American Great Plains is a prairie that includes lands from the eastern foothills of the Rocky Mountains east to Nebraska and north into Saskatchewan, including rangelands in Alberta, Wyoming, Montana, North Dakota, South Dakota, and Kansas, and extending to the south through the high plains of Colorado, Oklahoma, Texas, and New Mexico.
These rangelands were formerly maintained by grazing pressure of American bison, the keystone species; the dominant grasses are blue grama (Bouteloua gracilis) and buffalograss (Bouteloua dactyloides). The semi-arid climate receives on average less precipitation than that which supports the tallgrass prairie formerly to the east.
See also
- Hill, R.T. 1901. Geography and Geology of the Black and Grand Prairies, Texas. In: Walcott, C.D. (ed), Twenty-First Annual Report of the United States Geological Survey to the Secretary of the Interior (1899-1900), Part VII - Texas, 666 pp. (See Plate III)
|This article about a specific United States location is a stub. You can help Wikipedia by expanding it.|
|This ecoregion article is a stub. You can help Wikipedia by expanding it.|
|
<urn:uuid:b2628a09-6c59-411d-9e0b-0d3818862168>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-22T00:46:18",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368700958435/warc/CC-MAIN-20130516104238-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.8932017683982849,
"score": 3.53125,
"token_count": 279,
"url": "http://en.wikipedia.org/wiki/Shortgrass_prairie"
}
|
This project just makes a wireless fm microphone which looks very simple in its structure. It is a useful device in our day-today life. A wireless microphone, as the name implies, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated. More commonly known as a Radio Microphone, there are many different standards, frequencies and transmission technologies used to replace the microphone's cable connection and make it into a wireless microphone. They can transmit, for example, in radio waves using UHF or VHF frequencies, FM, AM, or various digital modulation schemes. Some low cost models use infrared light. Infrared microphones require a direct line of sight between the microphone and the receiver, while costlier radio frequency models do not. Some models operate on a single fixed frequency, but the more advanced models operate on a user selectable frequency to avoid interference and allow the use of several microphones at the same time. It can be used in seminar halls, class rooms, for a school or college radio etc. One such piece costs 100-300 rupees in the market. The coming sections give the entire idea of making a miniature wireless microphone. We hope that you will find this quite interesting as you go through this particular project.
2. BLOCK DIAGRAM AND ITS DESCRIPTION
Figure 1: Block Diagram
Above diagram shows the block diagram of the simple wireless fm microphone. It consists of simple audio amplifier, modulated tuned amplifier & a condenser mic. Here a microphone (condenser) captures the audio signal and a simple audio amplifier amplifies this signal before the modulation is done. A modulated tuned amplifier modulates the signal with self generated carrier frequency. The carrier frequency can be varied by changing the capacitor and inductor value in the tank circuit. Then the modulated signal is fed to the antenna. As a trimmer capacitor is used in the L-C circuit, we can vary the transmitting frequency anywhere in the whole FM band.
4. COMPONENTS DESCRIPTION
A resistor is a two terminal electronic component that opposes an electric current by producing a voltage drop between its terminals in its terminals in proportion to the current, that is in accordance with Ohm's law: V=IR. The electrical resistance R is equals to the voltage drop V across the resistor divided by the current / through the resistor. Resistors are used as part of electrical networks and electronic circuits.
An electrical signal can be amplified by using transistors that allows a small current or voltage to control the flow of a much larger current. In analog circuit transistors are used in oscillator, amplifier and linear regulated power supply. Transistors are also used in digital circuits where they function as electronic switches. Digital circuits include logic gates, RAM and micro processors. Here we use 2N3904 transistor. It is a common NPN bipolar junction transistor. It is used for general purpose low power amplifying and switching applications. It is designed for low current and power, medium voltage and can operate at moderately high speed. This transistor is of low cost and is widely available. When looking at the flat side,with the base pointed downwards, the three wires emerging from the base are, left to right, the emitter ,base and collector leads.
The inductor used in the circuit is a handmade coil using 22 SWG (Standard Wire Gauge) enameled copper wire. The length, inner diameter, number of turns etc are the important parameters to be considered while making the inductor. Then only the inductor resonates in the 88-108 band FM frequency. For this circuit, the coil radius was selected as 0.26 inches (outer diameter) and 0.13 inner diameter. Coil can be wound around a screw driver (with same diameter) to get a 5 turn coil of 0.2
inch long. Remove the coil from the screw driver and use the 5 turn Air core coil. Remove the enamel from the tips and solder close to the transistor.
The inductance of the coil can be calculated using the formula :
L =n2r2/ (9r + 10 x)
Where r is the inner radius of the coil, x is the length of the coil and n, number of turns. The resulting value is in Micro Henry.
An inductor is just a coil of wire and you need to wind one for this circuit. An inductor is characterized by its length, radius and the number of turns of wire in the coil. Magnet wire (Radio Shack part 278-1345) was used to build the inductor but you can use standard solid strand 22 AWG gauge copper wire. Some on-line and printed articles describe winding the wire around a pencil. Unfortunately, pencils come in different diameters and hence a McDonald’s soda straw was used; the yellow-red-white striped straw, found in every McDonalds in the world, is the same size. The straw’s radius is exactly 0.1325 inches (diameter = 0.2650 inches) and 1/4 inches was snipped off the straw.
4. 4 CONDENSER MIC
The condenser MIC is used to pick up the sound signals. The diaphragm inside the MIC vibrates according to the air pressure changes and generates AC signals. Variable resistor VR1 adjusts the current through the MIC and thus determines the sensitivity of MIC. The condenser MIC should be directly soldered on the PCB to get maximum sensitivity. Sleeving the MIC inside plastic tubing can increase its sensitivity error.
A capacitor is an electrical/electronic device that can store energy in the electric field between a pair of conductors (called "plates"). The process of storing
energy in the capacitor is known as "charging", and involves electric charges of equal magnitude, but opposite polarity, building up on each plate. Capacitors are often used in electric and electronic circuits as energy-storage devices. They can also be used to differentiate between high-frequency and low-frequency signals. This property makes them useful in electronic filters. Practical capacitors have series resistance, internal leakage of charge, series inductance and other non-ideal properties not found in a theoretical, ideal, capacitor.
4.6 TRIMMER CAPACITOR
A small button type variable capacitor with a value of 40 pF can be used to adjust the resonant frequency of the tank circuit. The variable capacitor and the inductor coil form the Tank circuit (LC circuit) that resonates in the 88-108 MHz. In the tank circuit, the capacitor stores electrical energy between its plates while the inductor stores magnetic energy induced by the windings of the coil. The resonant frequency can be calculated using the formula:
f = 1 / 2 π √LC = Hz
Where f is the frequency in hertz, x is the coil length, C is the capacitance of trimmer in Farads, and L is the inductance of coil in Henry.
4.7 TANK CIRCUIT
Every FM transmitter needs an oscillator to generate the radio Frequency (RF) carrier waves. The name ‘Tank’ circuit comes from the ability of the LC circuit to store energy for oscillations. The purely reactive elements, the C and the L simply store energy to be returned to the system. In the tank (LC) circuit, the 2N3904 transistor and the feedback 4.7 pF capacitor are the oscillating components. The feedback signal makes the base-emitter current of the transistor vary at the resonant frequency. This causes the emitter-collector current to vary at the same frequency. This signal fed to the aerial and radiated as radio waves.
A plastic wire or Telescopic aerial can be used as antenna. The length of the antenna is very important to transmit the signals in the suitable range. As a rule, the length of the antenna should be ¼ of the FM wave length. To determine the length of antenna, use the following equation. By multiplying the Wave frequency and wave length will give the speed of light.
Speed of Light = Frequency of Oscillation x Wavelength = in kms/ sec
Wave length = Speed of light / Frequency = in meters
Antenna length = 0.25 x wavelength = in meters
Antenna length = 0.25 x wavelength = in meters
By using this formula it is easy to select the antennal length. For the circuit mentioned above, a 25-27inches long antenna is sufficient.
5. FM (FREQUENCY MODULATION)
In telecommunications and signal processing, frequency modulation (FM) conveys information over a carrier wave by varying its instantaneous frequency. This is in contrast with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant.
In analog applications, the difference between the instantaneous and the base frequency of the carrier is directly proportional to the instantaneous value of the input signal amplitude. Digital data can be sent by shifting the carrier's frequency among a set of discrete values, a technique known as frequency-shift keying.Frequency modulation can be regarded as phase modulation where the carrier phase modulation is the time integral of the FM modulating signal.
FM is widely used for broadcasting of music and speech, and in two-way radio systems, in magnetic tape recording systems, and certain video transmission systems. In radio systems, frequency modulation with sufficient bandwidth provides an advantage in cancelling naturally-occurring noise.
Frequency-shift keying (digital FM) is widely used in data and fax modems.
Suppose the baseband data signal (the message) to be transmitted is xm(t) and the sinusoidal carrier is , where fc is the carrier's base frequency and Ac is the carrier's amplitude. The modulator combines the carrier with the baseband data signal to get the transmitted signal:
In this equation, is the instantaneous frequency of the oscillator and is the frequency deviation, which represents the maximum shift away from fc in one direction, assuming xm(t) is limited to the range ±1.
Although it may seem that this limits the frequencies in use to fc ± fΔ, this neglects the distinction between instantaneous frequency and spectral frequency. The frequency spectrum of an actual FM signal has components extending out to infinite frequency, although they become negligibly small beyond a point.
5.1.1 SINUSOIDAL BASEBAND SIGNAL
While it is an over-simplification, a baseband modulated signal may be approximated by a sinusoidal Continuous Wave signal with a frequency fm. The integral of such a signal is,
Thus, in this specific case, equation (1) above simplifies to:
where the amplitude of the modulating sinusoid, is represented by the peak deviation (see frequency deviation.
The harmonic distribution of a sine wave carrier modulated by such a sinusoidal signal can be represented with Bessel functions - this provides a basis for a mathematical understanding of frequency modulation in the frequency domain.
5.2 MODULATION INDEX
As with other modulation indices, this quantity indicates by how much the modulated variable varies around its un-modulated level. It relates to the variations in the frequency of the carrier signal:
where is the highest frequency component present in the modulating signal xm(t), and is the Peak frequency-deviation, i.e. the maximum deviation of the
instantaneous frequency from the carrier frequency. If , the modulation is called narrowband FM, and its bandwidth is approximately .
If , the modulation is called wideband FM and its bandwidth is approximately . While wideband FM uses more bandwidth, it can improve signal-to-noise ratio significantly. For example, doubling the value of while keeping fm constant, results in an eight-fold improvement in the signal to noise ratio. Compare with Chirp spread spectrum, which uses extremely wide frequency deviations to achieve processing gains comparable to more traditional, better-known spread spectrum modes.
With a tone-modulated FM wave, if the modulation frequency is held constant and the modulation index is increased, the (non-negligible) bandwidth of the FM signal increases, but the spacing between spectra stays the same; some spectral components decrease in strength as others increase. If the frequency deviation is held constant and the modulation frequency increased, the spacing between spectra increases.
Frequency modulation can be classified as narrow band if the change in the carrier frequency is about the same as the signal frequency, or as wide-band if the change in the carrier frequency is much higher (modulation index >1) than the signal frequency. For example, narrowband FM is used for two way radio systems such as Family Radio Service where the carrier is allowed to deviate only 2.5 kHz above and below the center frequency, carrying speech signals of no more than 3.5 kHz bandwidth. Wide-band FM is used for FM broadcasting where music and speech is transmitted with up to 75 kHz deviation from the center frequency, carrying audio with up to 20 kHz bandwidth.
5.3 CARSON'S RULE
A rule of thumb, Carson's rule states that nearly all (~98%) of the power of a frequency-modulated signal lies within a bandwidth of
where , as defined above, is the peak deviation of the instantaneous frequency from the center carrier frequency .
The noise power decreases as the signal power increases; therefore the SNR goes up significantly.
FM signals can be generated using either direct or indirect frequency modulation.
· Direct FM modulation can be achieved by directly feeding the message into the input of a VCO.
· For indirect FM modulation, the message signal is integrated to generate a phase modulated signal. This is used to modulate a crystal controlled oscillator, and the result is passed through a frequency multiplier to give an FM signal.
Many FM detector circuits exist. One common method for recovering the information signal is through a Foster-Seeley discriminator. A phase-locked loop can be used as an FM demodulator. Slope detection demodulates an FM signal by using a tuned circuit, which has its resonant frequency slightly offset from the carrier frequency. As the frequency rises and falls, the tuned circuit provides a changing amplitude of response, converting FM to AM. AM receivers may detect some FM transmissions by this means, though it does not provide an efficient method of detection for FM broadcasts.
FM is also used at audio frequencies to synthesize sound. This technique, known as FM synthesis, was popularized by early digital synthesizers and became a standard feature for several generations of personal computer sound cards.
Edwin Howard Armstrong (1890–1954) was an American electrical engineer who invented wideband frequency modulation (FM) radio. He patented the regenerative circuit in 1914, the super-heterodyne receiver in 1918 and the super-regenerative circuit in 1922. He presented his paper: "A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation", which first described FM radio, before the New York section of the Institute of Radio Engineers on November 6, 1935. The paper was published in 1936.
As the name implies, wideband FM (WFM) requires a wider signal bandwidth than amplitude modulation by an equivalent modulating signal, but this also makes the signal more robust against noise and interference. Frequency modulation is also more robust against simple signal amplitude fading phenomena. As a result, FM was chosen as the modulation standard for high frequency, high fidelity radio transmission: hence the term "FM radio" (although for many years the BBC called it "VHF radio", because commercial FM broadcasting uses a well-known part of the VHF band—the FM broadcast band).FM receivers employ a special detector for FM signals and exhibit a phenomenon called capture effect, where the tuner is able to clearly receive the stronger of two stations being broadcast on the same frequency. Problematically however, frequency drift or lack of selectivity may cause one station or signal to be suddenly overtaken by another on an adjacent channel. Frequency drift typically constituted a problem on very old or inexpensive receivers, while inadequate selectivity may plague any tuner.
An FM signal can also be used to carry a stereo signal: see FM stereo. However, this is done by using multiplexing and de-multiplexing before and after the FM process. The rest of this article ignores the stereo multiplexing and de-multiplexing process used in "stereo FM", and concentrates on the FM modulation and demodulation process, which is identical in stereo and mono processes.
A high-efficiency radio-frequency switching amplifier can be used to transmit FM signals (and other constant-amplitude signals). For a given signal strength (measured at the receiver antenna), switching amplifiers use less battery power and typically cost less than a linear amplifier. This gives FM another advantage over other modulation schemes that require linear amplifiers, such as AM and QAM.
Frequency-shift keying is the frequency modulation using only a discrete number of frequencies. Morse code transmission has been implemented this way, as were most early telephone-line modems Radio teletype also use FSK.
FM modulation is also used in telemetry applications, radar, seismic prospecting and newborn EEG seizures modeling.
5.9 SUPER HETERODYNE RECIEVER
In electronics, a super heterodyne receiver (sometimes shortened to superhets) uses frequency mixing or heterodyning to convert a received signal to a fixed intermediate frequency, which can be more conveniently processed than the original radio carrier frequency. Virtually all modern radio and television receivers use the super heterodyne principle.
The diagram at right shows the minimum requirements for a single-conversion super heterodyne receiver design. The following essential elements are common to all superhet circuits:[ a receiving antenna, a tuned stage which may optionally contain amplification (RF amplifier), a variable frequency local oscillator, a frequency mixer, a band pass filter and intermediate frequency (IF) amplifier, and a demodulator plus
additional circuitry to amplify or process the original audio signal (or other transmitted information).
Figure : Block Diagram of Super heterodyne Receiver
5.10 CIRCUIT DESCRIPTION
To receive a radio signal, a suitable antenna is required. This is often built into a receiver, especially in the case of AM broadcast band radios. The output of the antenna may be very small, often only a few microvolts. The signal from the antenna is tuned and may be amplified in a so-called radio frequency (RF) amplifier, although this stage is often omitted. One or more tuned circuits at this stage block frequencies which are far removed from the intended reception frequency. In order to tune the receiver to a particular station, the frequency of the local oscillator is controlled by the tuning knob (for instance). Tuning of the local oscillator and the RF stage may use a variable capacitor, or varicap diode. The tuning of one (or more) tuned circuits in the RF stage must track the tuning of the local oscillator.
5.11 MIXER STAGE
The signal is then fed into a circuit where it is mixed with a sine wave from a variable frequency oscillator known as the local oscillator (LO). The mixer uses a non-linear component to produce both sum and difference beat frequencies signals, each one containing the modulation contained in the desired signal. The output of the mixer may include the original RF signal at fd, the local
oscillator signal at fLO, and the two new frequencies fd+fLO and fd-fLO. The mixer may inadvertently produce additional frequencies such as 3rd- and higher-order intermediation products. The undesired signals are removed by the IF bandpass filter, leaving only the desired offset IF signal at fIF which contains the original modulation (transmitted information) as the received radio signal had at fd.
Historically, broadcast AM receivers using vacuum tubes would save costs by employing a single tube as a mixer and also as the local oscillator. The pentagrid converter tube would oscillate and also provide signal amplification as well as frequency shifting.
5.12 INTERMEDIATE FREQUENCY STAGE
The stages of an intermediate frequency amplifier are tuned to a particular frequency not dependent on the receiving frequency; this greatly simplifies optimization of the circuit. The IF amplifier (or IF strip) can be made highly selective around its center frequency fIF, whereas achieving such a selectivity at a much higher RF frequency would be much more difficult. By tuning the frequency of the local oscillator fLO, the resulting difference frequency fLO - fd (or fd-fLO when using so-called low-side injection) will be matched to the IF amplifier's frequencyfIF for the desired reception frequency fd. One section of the tuning capacitor will thus adjust the local oscillator's frequency fLO to fd + fIF (or. less often, to fd - fIF) while the RF stage is tuned to fd. Engineering the multi-section tuning capacitor and coils to fulfill this condition across the tuning range is known as tracking.Other signals produced by the mixer (such as due to stations at nearby frequencies) can be very well filtered out in the IF stage, giving the superheterodyne receiver its superior performance. However, if fLO is set to fd + fIF , then an incoming radio signal at fLO + fIF will also produce a heterodyne at fIF; this is called the image frequency and must be rejected by the tuned circuits in the RF stage. The image frequency is 2fIF higher (or lower) than fd, so employing a higher IF frequency fIF increases the receiver's image rejection without requiring additional selectivity in the RF stage.
Usually the intermediate frequency is lower than the reception frequency fd, but in some modern receivers (e.g. scanners and spectrum analyzers) it is more convenient to first convert an entire band to a much higher intermediate frequency; this eliminates the problem of image rejection. Then a tunable local oscillator and mixer converts that signal to a second much lower intermediate frequency where the selectivity of the receiver is accomplished. In order to avoid interference to receivers, licensing authorities will avoid assigning common
IF frequencies to transmitting stations. Standard intermediate frequencies used are 455 KHz for medium-wave AM radio, 10.7 MHz for broadcast FM receivers, 38.9 MHz (Europe) or 45 MHz (US) for television, and 70 MHz for satellite and terrestrial microwave equipment.
5.13 BANDPASS FILTER
The received The IF stage includes a filter and/or multiple tuned circuits in order to achieve the desired selectivity. This filtering must therefore have a band pass equal to or less than the frequency spacing between adjacent broadcast channels. Ideally a filter would have a high attenuation to adjacent channels, but maintain a flat response across the desired signal spectrum in order to retain the quality of signal. This may be obtained using one or more dual tuned IF transformers or a multipole ceramic crystal filter.
The received signal is now processed by the demodulator stage where the audio signal (or other baseband signal) is recovered and then further amplified. AM
demodulation requires the simple rectification of the RF signal (so-called envelope detection), and a simple RC low pass filter to remove remnants of the intermediate frequency. FM signals may be detected using a discriminator, ratio detector, or phase-locked loop. Continuous wave (morse code) and single sideband signals require a product detector using a so-called beat frequency oscillator, and there are other
techniques used for different types of modulation. The resulting audio signal (for instance) is then amplified and drives a loudspeaker. When so-called high-side injection has been used, where the local oscillator is at a higher frequency than the received signal (as is common), then the frequency spectrum of the original signal will be reversed. This must be taken into account by the demodulator (and in the IF filtering) in the case of certain types of modulation such as single sideband.
6. CIRCUIT DIAGRAM OF WIRELESS FM MICROPHONE
7. CIRCUIT DESCRIPTION
The above figure shows the circuit diagram of wireless FM microphone .It has two transistor stages. The first one is the common emitter amplifier .The second stage is the voltage controlled oscillator. Capacitor and self-made inductor will vibrate at frequencies in the FM radio band (88 to 108 MHz) and it constitutes the L-C circuit. It is also called tank circuit. It consists of one inductor and two capacitors. This is called Colpitt's oscillator. The physics lying behind this is that the capacitor stores charges between its plates, while the inductor coil stores energy in the magnetic field induced by the coil winding. The tank circuit vibrates at resonant frequency. The resonant frequency is given by
f = 1 / 2 π √LC Hz
Where f is the frequency in hertz, C is the capacitance of trimmer in Farads, and L is the inductance of coil in Henry. The performance of an FM transmitter depends on two important aspects
· Tuning of the FM transmitter to the desired frequency. Even a slight change in the coil specification or slight change in the variable capacitor value can shift the harmonic frequency of the 88 to 108 MHz FM band.
· Length of the Antenna used to transmit the frequency.
The important parameters for the optimum performance of an FM transmitter are :
· Transmitter frequency, output power and range of transmission.
· Antenna length.
· Coil diameter, length, number of turns and gauge of the wire used for coil winding.
The electric microphone has a resistance that depends on how loudly you speak into it. This microphone is battery powered and according to the V=IR Ohm’s Law,
changes in resistance for fixed voltage will result in proportional changes in current. This wireless FM microphone is easy to construct and its transmissions can be picked up on any standard FM radio. It has a range of up to 1/4-mile (400 meters) or more, depending on the line of sight, obstructions by large buildings, etc. If you decide to substitute transistors with something similar you already have, it may be necessary to adjust the collector voltage of Q1 by changing the value of R2 or R3 (because you change transistors, it changes this bias on the base of Q1). It should be about half the supply voltage (about 4 or 5). To find the signal on receiver, make sure there is a signal coming in to the microphone, otherwise the circuit won't work.
To use the microphone, set up a radio in the area at least 10 feet (3 meters) from the project. Find a blank spot on the FM dial and tune the radio up so you can hear the static. Connect a 9-volt battery to the transmitter and listed to the radio. Slowly adjust the trimmer capacitor until "quiet" the receiver; this is the tuned spot. When move hand from the transmitter, then detune the circuit somewhat. It is usually best to leave it detuned and tune the radio in to get the best reception. If you get the tuning range you desire, you can squeeze the coils in the tank circuit closer together to raise the frequency, or pull them apart just a little to lower it.
8. PCB DESIGN
8. 1 PCB DESIGN PROCEDURE
PCB preparation can be done using the following steps.
· Prepare the PCB layout of the circuit in a graph sheet.
· Cut the copper clad sheet in proper dimension and wash it.
· PCB layout is coated with paint or sticker.
· Prepare the ferric chloride solution
· Dip the PCB in to Ferric chloride solution for etching non printed surface.
· Wash cleanly with detergent.
· Drill the holes in necessary any position.
9. PCB LAYOUT
Soldering is the process of joining two or more similar or dissimilar maters by melting another meters having lower melting points. Soldering is an alloy of tin and lead, used for fusing the metals at relatively low temperature about 260uk to 315uk.The joint where the two metal conductors are to be fused is heated and solder is applied so that it can melt and cover the connection. The reason for soldering connections is that it makes a good bond between the joining metals , covering the joints completely to prevent oxidization. The coating of solder provides protection for practically long period of time. The trick in soldering is to heat the joint, not the solder. When the soldering is hot enough to melt the solder, it follows smoothly to fill all cracks forming a shiny cover without any space. Do not move the joint until the solder has set. Either the soldering iron or soldering gun can be used rated at 25W to 100W.In addition to this solder flux is used to remove any oxide films on the metal being joint. Otherwise they cannot be joined together.
9.1 SOLDERING FLUXES
In order to make the surface accept the solder readily, the component terminals should be for from order and other abstractly films. Soldering flux cleans the orders from the surface of the metal. Zinc chloride, aluminums chloride, and rosin at the commonly used fluxes.
Solder is used for joining two or more mental at temperature below their melting point. The popularly used solders on alloy are alloys of tin (60%) and lead (40%) that metals at stiff and solidifies when it cools.
9.3 SOLDERING IRON
It is used the melt the solder and apply at the joints in the circuit.
Ø Working with a simple dry cell power supply.
Ø It is user friendly.
Ø Low cost.
Ø Easy to install.
Ø Simple circuit.
Ø Greater freedom of movement for the artist or speaker.
Ø Avoidance of cabling problems common with wired microphones, caused by constant moving and stressing the cables.
Ø Sometimes limited range (a wired balanced XLR microphone can run up to 300 ft or 100 meters). Some wireless systems have a shorter range, while more expensive models can exceed that distance.
Ø Possible interference with or, more often, from other radio equipment or other radio microphones, though models with many frequency-synthesized switch-selectable channels are now plentiful and cost effective.
Ø Operation time is limited relative to battery life; it is shorter than a normal condenser microphone due to greater drain on batteries from transmitting circuitry, and from circuitry giving extra features, if present.
Ø Noise or dead spots (places where it doesn't work, especially in non-diversity systems).
Ø Limited number of operating microphones at the same time and place, due to the limited number of radio channels (frequencies).
Ø It is used in seminar halls, class rooms, for a school or college radio etc.
The mini project 'wireless FM microphone' is developed from the elementary idea of making a wireless hand piece, which can be used in a seminar hall, auditorium etc. This idea forced us to proceed with our project. As our project deals with transmitter & the most common receiver is FM receiver, we decided to make the FM Transmitter.
15. FUTURE SCOPE
As the field of Information Technology and Communication is developing day-by-day, the necessity of more sophisticated equipments and discoveries is raising up. Hence, more enhanced version of our project, wireless FM microphone can be implemented in various circuits.
|
<urn:uuid:7a89424a-adcc-499c-a57c-a51f0cf88bc6>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-22T00:29:38",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368700958435/warc/CC-MAIN-20130516104238-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9220479726791382,
"score": 3.5,
"token_count": 6565,
"url": "http://www.morldtechgossips.com/2012/05/wireless-fm-microphone.html"
}
|
Glue ear, grommets (ventilation tubes) and adenoids
Mr James W Fairley BSc MBBS FRCS MS
Consultant ENT Surgeon
© 1993 - 2013 JW Fairley Last updated 11 November 2010
- What is glue ear?
- The normal ear and hearing
- What causes glue ear?
- What are adenoids?
- What are the symptoms of glue ear?
- How is glue ear diagnosed?
- What is the treatment?
- What about alternative treatments?
- What is a grommet / ventilation tube - how does it work?
- How is the operation done?
- What happens after the operation?
- What about swimming and grommets?
- Does fluid discharge from the ear?
- How to treat ear infection in the presence of a grommet
- How to use ear drops
- How will you know if you have an ear infection with a grommet?
- What happens after the grommet comes out?
- How do you know when the grommet is out?
- Do grommets scar the eardrum?
- What are the complications of grommets?
- I've heard that grommet operations are unnecessary
- Further reading / links
What is glue ear?
Glue Ear is a build-up of fluid behind the eardrum, in the middle ear.
Glue ear with fluid level behind right eardrum
- The fluid may be thick and sticky, or thin and watery.
- Either way it stops the ear drum and ossicles vibrating easily, so quieter sounds are not heard.
- Glue ear is the commonest cause of deafness in children.
- Adults can also be affected.
- Other names for glue ear are middle ear effusion and chronic secretory otitis media.
Glue ear is a middle ear disease, associated with poor Eustachian tube function.
The outer and middle ear work like an old mechanical gramophone in reverse. They collect sound energy, and concentrate it onto the small area of the stapes footplate
The normal ear and hearing
The human ear is divided into three parts:
- outer ear
- middle ear
- inner ear
The outer ear consists of the pinna and the ear canal. The outer ear funnels sound waves in air to the eardrum.
Eardrum (tympanic membrane)
Normal left eardrum (tympanic membrane)
The eardrum is a paper-thin membrane, shaped like a miniature satellite dish, 8-10 mm diameter. The tympanic membrane forms the boundary between outer and middle ear.
The eardrum vibrates when sounds arrive through the external ear canal. The vibrations are transmitted to the inner ear via three small bones (ossicles) suspended in the middle ear.
Abnormally thin right eardrum damaged by glue ear and showing ossicles - malleus incus and stapes
The three little bones (oss-i-culls) are
- malleus (mal-ee-us) shaped like a hammer
- incus (ink-us) shaped like an anvil
- stapes (stay-peas) shaped like a stirrup
Their job is to concentrate the sound energy, collected by the relatively large area of the eardrum, onto the tiny footplate of the stapes.
The outer and middle ear work like an old mechanical gramophone in reverse. The gramophone needle picks up vibrations from the grooves in the record, passes them to a vibrating membrane, then into the large horn, and so to the outside world. The outer and middle ear collect sound from the outside world and concentrate it down to the stapes footplate. The footplate moves like a piston in the oval window, the opening of the inner ear.
The inner ear has two parts, the cochlea and the vestibular labyrinth.
CochleaThe cochlea is the hearing part of the inner ear. It is a biological microphone. Sound vibrations are turned into electrical signals and sent to the brain in the nerve of hearing.
The vestibular labyrinth of the inner ear is concerned with balance. Disturbance of the balance organ of the inner ear can cause vertigo.
The Eustachian tube connects the middle ear with the back of the nose. To hear normally, the eardrum and ossicles must be able to move easily. For this to occur, the middle ear must contain air at the same atmospheric pressure as the outer ear. Air in the middle ear comes from the back of the nose, via the Eustachian tube. The job of the Eustachian tube is to ventilate the middle ear, keeping the pressure in the middle ear the same as in the outer ear. Most middle ear diseases, including glue ear, are associated with poor Eustachian tube function. The health of the middle ear depends on the Eustachian tube working properly.
What causes glue ear?
Glue ear is usually caused by a problem with the Eustachian tube.
Temporary glue ear (less than 3 months)
- Most children get glue ear at some stage in their lives.
- It often follows after a cold or ear infection. Biofilms may form in some cases.
- The Eustachian tube is small and blocks easily.
- It then fails to ventilate the middle ear.
- Sticky secretions can't drain away, so fluid builds up in the middle ear.
- Movement of the eardrum and ossicles is impaired, causing partial deafness.
Most cases get better quickly after the cold resolves. A minority persist for months or years.
- Occasionally glue ear is caused by flying with a cold - the Eustachian tube is unable to equalise pressure during descent
- Diving with a cold is very likely to cause glue ear, or worse damage. All divers are taught not to dive with a cold.
Persistent glue ear (longer than 3 months)
Common reasons for persistent glue ear in children are
Sometimes glue ear runs in families, though it is not strictly speaking hereditary.
Less common reasons for persistent glue ear include
- Cleft palate
- Down's syndrome
Rarely, glue ear in an adult is caused by a tumour at the back of the nose.
Often, no particular cause is found.
Adenoids seen through a nasal endoscope. The Eustachian tubes open either side of the adenoids at the back of the nose. Swollen adenoids interfere with the normal opening of the Eustachian tube.
What are adenoids?
Adenoids are cauliflower-like swellings of the immune tissue at the back of the nose.
- Normal adenoids probably help fight off infections.
- If they get too big, they cause blockage of the nose and Eustachian tube and cause more trouble than they are worth.
- In severe cases they can cause obstruction of breathing at night.
If the adenoids are very big, the tonsils are usually big too.
What are the symptoms of glue ear?
- Deafness of mild to moderate degree.
- Hearing loss often varies from week to week, being worse after a cold.
- Speech may be delayed, especially if deafness occurs early in childhood.
- Unclear speech and constant shouting are common.
- Later, education may be affected.
- Sometimes deafness is not suspected, but the child is thought to be inattentive, slow or lazy.
- Concentration may be poor.
- The child often seems to be "in a world of his own".
- Some sufferers get frequent earaches, usually worse at night.
- Repeated ear infections, with high temperature in some cases leading to fits.
- Poor balance and clumsiness may feature.
- Older children and adults often complain of noises in the ears - tinnitus.
How is glue ear diagnosed?
Child ear examination with auriscope (ear torch)
Child hearing test - pure tone audiometry in sound proofed booth. Test suitable for children from around the age four.
Child hearing test - Brain Stem Electric Response under general anaesthetic in operating theatre. Test suitable for babies and children of any age.
Diagnosis is based on history, examination and special investigations.
- The specialist may be able to see signs of fluid behind the eardrum with the otoscope (ear torch).
- This is not always possible, wax or discharge may block the view.
- Some children may not be sufficiently cooperative for examination.
- A tympanogram is a test carried out by the audiologist to check on how easily the eardrum moves. It takes about a minute. It is not a test of hearing ability, but a physical test on the movement of the eardrum. A flat trace on the tympanogram usually means glue ear.
- An audiogram (hearing test) is carried out on children old enough to cooperate with the test. This will help assess the degree of hearing loss.
- Sometimes, the only way to make the diagnosis is under general anaesthetic on the operating table.
What is the treatment?
The fluid frequently goes away by itself, so a policy of watchful waiting is usually advised. Around the age of 8, many children grow out of it, though this is only the average. Some will carry on having trouble into their teens.
- Blowing up balloons or an Otovent® device, to try and force air up the Eustachian tube, may help but the published results are very short term and not many children will persist with this treatment.
- Any exacerbating factors should be eliminated especially passive smoking.
- Antibiotics and painkillers e.g. Calpol® can be used for associated ear infections.
- Decongestants e.g. Sudafed® are often prescribed but have never been proven effective.
- Other medical treatments including
- medicines to try and thin sticky mucus
- Dietary modification - cutting down on dairy products - is often advocated but again is of no proven benefit, and does carry risks in children who need their calcium
Better in summer, worse in winter
Glue ear can be seasonal, worse in the winter and better in the summer.
- An operation may be deferred if the child is seen in the spring.
- An operation is more likely to be recommended in the autumn.
Persistent glue ear (longer than 3 months)
- If deafness persists for longer than 3 months, an operation is usually needed.
- The decision to operate is always individual, based on all the factors in that particular case.
- For immediate relief, myringotomy and grommets insertion is highly effective.
- Removal of the adenoids may be recommended if the adenoids are enlarged, and where glue ear recurs after initial grommet insertion.
What about alternative treatments?None of the following are of any proven help:
- Homeopathic medicines
- Chinese / Hopie ear candles
- Cranial osteopathy
Although many parents have seen improvements in their child following the use of various treatments, this is almost certainly because of the natural tendency for glue ear to improve. If half the children are going to get better anyway, we would expect a 50% success rate from a treatment with no real benefit, so long as it didn't make things worse. This is known as the placebo effect. We would also expect a 50% improvement on no treatment at all.
A few ENT specialists recommend the use of hearing aids for children with persistent glue ear, hoping that the fluid will eventually clear without recourse to grommets. Sometimes, if glue ear has persisted a long time, the eardrum may become permanently damaged and will not hold a grommet. In such cases, a hearing aid may be the only way of restoring hearing.
What is a grommet / ventilation tube - how does it work?
Shah grommet held between forefinger and thumb
Shah grommet in position right eardrum - abnormally thin due to longstanding retraction prior to fitting grommet. Head of stapes visible, long process of incus partially eroded
Long term Shah ventilation tube in position right ear
eac = external ear canal
vt = ventilation tube
tm = tympanic membrane (eardrum)
The long term ventilation tube is larger than the standard grommet.
A grommet is a tiny plastic tube, shaped like a miniature cotton reel, about 2mm diameter.
It is fitted through a small cut in the eardrum (myringotomy). The tension of the eardrum grips the grommet around its waist. The cotton-reel shape stops it falling in or out, like a shirt stud in a button hole.
The grommet allows air from the outer ear directly into the middle ear. Provided the grommet remains in position and is not blocked, the hearing returns to normal almost immediately.
A grommet does not drain, it ventilates - lets air in
The grommet does not drain fluid out, it lets air into the middle ear.
Another name for a grommet is a Ventilation Tube, sometimes abbreviated to Tube or VT. They can also be called Tympanostomy Tubes or TT's.
Short term and long term grommets
The standard Shah grommet is designed to stay in position for about nine months. Then the opening in the eardrum heals over, and the grommet is pushed out. Longer term ventilation tubes are sometimes fitted, which can last for several years. But long term grommets are more likely to leave a perforation which may need repair later.
Grommets don't treat underlying cause of glue ear
It is important to understand that a grommet does not cure the underlying cause of glue ear.
Grommets do help relieve deafness and earache - for a while
A grommet does provide highly effective and immediate relief of deafness and earaches. The grommet only works while it is
- in the right position (in the eardrum connecting the middle ear with the outer ear canal)
- able to ventilate (not blocked)
A grommet / ventilation tube buys time, and allows normal education. Meanwhile the child has a chance to grow out of the underlying causes of glue ear.
If adverse factors, such as passive smoking, are not dealt with, there is an increased risk that the glue ear will come back once the grommets come out.
How is the operation done?
Anaesthetic cream applied to hands before surgery
Grommet insertion with operating microscope under general anaesthetic
Grommet held with crocodile forceps and passed down funnel-like ear speculum
Grommet insertion with curved needle using operating microscope
Grommets insertion is normally a quick and simple day-case procedure.
The operation is very delicate, and normally done under general anaesthetic (patient fully asleep). The anaesthetic is usually given by injection into a vein in the back of the hand, or by gas. To prevent the needle from hurting, a local anaesthetic cream is applied about an hour beforehand.
- Further information on General Anaesthesia for children
- Further information on General Anaesthesia for adults
No external cut is needed. Everything is done down the natural opening of the ear canal, using a funnel shaped speculum.
- A microscope provides a magnified view of the eardrum.
- A small cut (myringotomy) is made in the eardrum, and the fluid in the middle ear is sucked out. The cut is like a tiny button hole in the eardrum.
- Sometimes, if the glue is very thick and sticky, like treacle, a second cut is needed. The second opening allows air in to the middle ear while the glue is sucked out. Sometimes ear drops have to be pumped in to thin the glue in order to suck it out.
- The grommet is fitted. It is held in position by the tension of the eardrum gripping it around the waist. The grommet's shape stops it falling in or out, like a shirt stud in a button hole. If the eardrum is badly thinned, stretched and damaged, it might not have the strength to hold a standard grommet in place. A bigger grommet (long term ventilation tube) might be used in such a case.
- Some eardrops are ususally applied at the end of the procedure.
If the adenoids are to be removed, this is normally done under the same anaesthetic. The adenoids are removed via the mouth. No external cut is needed.
What happens after the operation?
After grommet operation
Children recover very rapidly from grommets insertion, and should be able to return to school after a day or two.
How long before the hearing improves?
The hearing normally improves immediately, but don't worry if there is still some difficulty in the first weeks as it can take time in some cases. If the glue was very thick, you may be asked to use some ear drops for a week.
Earache and bleeding from the ear
- There may be a very slight earache, treated easily with Calpol, or paracetamol for older children.
- There may be slight bleeding from the ear in the first few days after the operation. This is normal and nothing to worry about.
- The child should stay off school for 10 days and avoid contact with anyone who has a cold or other infection.
- There is a small risk of heavy bleeding from the nose.
- If this occurs you should telephone the hospital and/or attend your nearest Accident & Emergency department.
Ear plugs held in place by neoprene headband
What about swimming and grommets?
No swimming for the first two weeks.
- After the first out-patient visit, to check all is well, surface swimming is allowed without earplugs.
- If your child wishes to dive or use water chutes, some well fitting silicone rubber earplugs such as Kapiseal® or Ear Putty® should be worn, preferably with a neoprene headband such as the Ear Band-it® to stop them from falling out.
- Bath water is much worse than swimming pool water, because it contains germs from the rest of the body and irritant soap.
- Bath water should not be allowed in the ears. The head should not be submerged in the bath.
- For hairwashing, either use earplugs, or a piece of cotton wool dipped in Vaseline® to provide a waterproof seal.
Does fluid discharge from the ear?
- In the first few days after operation there may be a slight discharge or bleeding from the ear. This is normal and nothing to worry about.
- After that there should be no discharge.
- If the ear runs persistently, and especially if the discharge is smelly, that means an ear infection.
- The infection is usually in the middle ear. The discharge comes out through the grommet. In severe cases it will not be possible to see the grommet because the discharge fills the ear canal (see photo).
- Infection may be caused by dirty water in the ear, or a cold.
How to treat ear infection in the presence of a grommet
- The infection is best treated with antibiotic/steroid eardrops such as Sofradex® or Gentisone HC®.
- The manufacturers of these drugs do not recommend using them in the presence of a perforated eardrum, because of the risk that the aminoglycoside antibiotic in the drops could cause damage to the inner ear and deafness.
- Despite these reservations, most ENT specialists agree that the risk of deafness from the infection is greater than the risk of using the drops, and that these combined antibiotic steroid drops are the most reliable way of treating ear infection in the presence of a grommet.
- In 2007, ENT-UK published recommendations on treating patients discharging ears in the presence of a perforated eardrum or grommet. Aminoglycoside ear drops should only be used to treat obvious infection, and for no longer than 2 weeks. Whenever possible and practical, a hearing test should be done before treatment.
- Another type of antibiotic drops, containing a quinolone which is does not carry any risk of damaging the inner ear, is Ciprofloxacin. At present, this is only available in the UK as Ciloxan® eye drops, and not as a combined product with steroids. Combined quinolone and steroid ear drops such as Ciflox® are in use in other countries, and have been imported into the UK by the pharmacy at Great Ormond Street Hospital, but are still not generally available. The use of a quinolone avoids the tiny risk of damaging the ear from the aminoglycoside. Since the ENT specialists preference for quinolones over aminoglycoside ear drops was clearly expressed in a British Medical Journal editorial in 2000, it is not clear why there has been such a delay in getting this combination licensed for use in the UK. Similar delays occurred in Australia until recently.
- In persistent infection and especially tube granuloma where bacteria become attached to the surface of the grommet as biofilm, causing a foreign body reaction and bleeding from surrounding eardrum, the grommet may have to be removed.
How to use ear drops
Correct position for putting in eardrops
- Ear drops must be inserted correctly, otherwise they may not work.
- Eardrops should be applied at body temperature.
- To get the drops to body temperature, put the bottle in your pocket for 15 - 20 minutes before use
- The patient should lie on his side with the affected ear uppermost.
- Any discharge should be mopped gently away with a cotton bud.
- Pull the ear gently backwards to funnel the drops into the ear canal.
- You then massage the tragus (the piece of skin that sticks out just in front of the ear canal like an open trapdoor) to force the drops through the grommet into the middle ear.
- It is rather like plunging a blocked sink.
- The infection should clear up within a few days.
- Antibiotics taken by mouth are not very good in treating ear infections where there is a grommet present.
How will you know if you have an ear infection with a grommet? Is the temperature raised?
- Discharge (fluid running from the ear) is the main sign of infection with a grommet.
- The discharge may be any colour. Pale green, creamy yellow and orange brown are common. It may be bloody.
- Sometimes it will be painful, but often there is little or no pain.
- Temperature is usually normal, unlike an acute otitis media when the temperature will be raised.
What happens after the grommet comes out?The grommet only helps while it is in the eardrum and open. The eardrum normally heals up and pushes the grommet out after six to twelve months. The time can taken varies from a few weeks to several years. Once the grommet has come out of the eardrum, it is no longer working.
- In 2 out of 3 cases, the hearing remains normal, there is no further build-up of fluid, and the condition is cured.
- If the Eustachian tube is still blocked, the glue ear can recur, and it may be necessary to operate again in 1 in 3 cases.
- Of patients who have a second set of grommets, about 1 in 3 will require a third, (1 in 9 overall) of those 1 in 3 will require a fourth set (1 in 27 overall) and so on.
- If the hole in the eardrum does not heal up, it may be necessary to repair it at a later date.
How do you know when the grommet is out?
A loose grommet lying in the ear canal, one year after it was fitted. Grommets are pushed out of the eardrum by the growth of skin around the flange. They are carried slowly outwards along the natural migration pathways of the ear canal skin.
Often, you won't know. If the grommet comes out, the eardrum heals up, and the glue ear doesn't come back, there may be no symptoms at all. That is why we recommend periodic check-ups, so we can tell you what is happening.
- Most patients don't notice anything when the grommet comes out.
- There may be a slight pain or discomfort.
- Occasionally, the grommet comes out with an ear infection, in which case there may be discharge or bleeding from the ear.
When we say the grommet has come out, we mean out of the ear drum. A grommet can sit in the ear canal, having come out of the ear drum. Sometimes it can be hard to tell, even for a specialist, whether a grommet is still in the right place. Wax, layers of skin, dried discharge, or a sharp bend in the ear canal, can all prevent a proper view.
- When a grommet is just sitting in the ear canal, it is not working.
- It is no longer doing any good.
- Mostly, it is not doing any harm either, and we just wait for it to come right out by itself.
Being very small, you won't always see a grommet when it comes out. They can easily get lost in the bedding. This doesn't matter. You don't need to keep a lookout for grommets. You should, however, pay attention to any recurrence of
- hearing problems
- bleeding from the ear
Any of these could indicate a problem needing further treatment. What happens to the grommet isn't too important. It's what happens to the ear that matters.
Will the ear bleed when the grommet comes out?
- Bleeding from the ear is most often caused by a tube granuloma.
- It is a sign of infection.
- Usually, if caught early, it can be treated successfully with ear drops.
Do grommets scar the eardrum?Yes. But the scar doesn't have any noticeable effect on hearing. It is less of a problem than the scarring caused by repeated ear infections.
What are the complications of grommets?
Infected ventilation tube mucoid discharge with bubbles from middle ear
Tube granuloma left ear. Long term ventilation tube colonised with biofilm and blocked with mucopus. Key:
g = granuloma
eac = external ear canal
vt = ventilation tube
tm = tympanic membrane (eardrum)
Cholesteatoma left ear white keratin bone eroded from outer attic wall
Most grommet operations are straighforward and it is unlikely anything will go wrong. But all surgical procedures have risks. Apart from the general risk of having an anaesthetic in hospital, the particular complications of grommets are
- Infection. Normally shows as a discharge from the ear. Best treated with eardrops, they must be correctly applied in order to work properly.
- Persistent infection tube granuloma, often with bleeding from the ear. Probably due to bacteria becoming attached to the surface of the grommet as a biofilm and causing a reaction in the surrounding eardrum. If caught early, will usually respond to treatment with eardrops. Otherwise, the grommet may have to be removed to settle this infection.
- Perforated eardrum. The hole where the grommet was put does not always heal up. This may require further surgery to repair the perforated eardrum at a later stage. A grommet that stays in a long time (years) is more likely to leave a perforation. This does not necessarily mean the grommet should be removed. An eardrum which does not have very active healing will not push the grommet out. A grommet which stays in too long is probably the result, rather than the cause, of the perforation.
- Cholesteatoma. A ball of skin erodes the middle ear structures. Said to be a rare complication of grommet insertion. More likely that a small cholesteatoma (which may co-exist with glue ear) is not noticed at the first operation to fit a grommet. The cholesteatoma then grows and becomes obvious later.
I've heard that grommet operations are unnecessary
Insertion of grommets is the commonest operation performed on children in the UK and there has been controversy over how many of these operations are really necessary. In most cases, glue ear is a temporary self-limiting condition. Although grommets give immediate improvement in hearing, it is not sensible to subject a child to surgery if they are about to get better on their own. The difficulty lies in predicting who is going to get better without surgery and who is not. No-one has a completely accurate crystal ball for this, but experience allows us to have a fair idea. Factors that make us recommend grommets are:
- Length of history - the longer fluid has persisted, the less likely it is to clear up on its own. We would normally wait at least three months before deciding on grommets.
- Age of the child - the younger the child, the less likely the glue ear will clear up. The normal age for "growing out of" glue ear is eight or nine.
- Severity of the hearing loss - the more severe the loss of hearing, the more likely grommets will be recommended.
- The time of year - glue ear tends to get better in the spring and summer, worse in the autumn and winter. If we see a child with glue ear at the end of the summer, the chances are it will get worse not better, so an operation is more likely to be needed.
- Previous and family history - a child who has had glue ear before, or comes from a family where glue ear is common, is more likely to need grommets.
- Observing progressive damage to the eardrum - if the eardrum appears to be sucked in and thinned, or develops a retraction pocket, surgery is more likely to be recommended to try and prevent permanent damage. Sometimes the damage will progress anyway, even if grommets are fitted and adenoids removed.
- Earaches and infections - a child subject to frequent earaches and infections will get more benefit from grommets.
We may monitor the condition for months, or occasionally even years, before operating.
- We only operate on patients who have had a reasonable chance to get better on their own, yet show no signs of improvement.
- We do not carry out any unecessary operations.
- The pros and cons of surgery, and any possible alternatives, are always fully discussed before a decision is made.
- That decision is made solely in the best interests of the patient, following the principle of how we would like a member of our own family treated.
Further reading / links
- National Deaf Children's Society - parent-friendly guide to glue ear
- NHS Direct
- NHS Direct information sheet on glue ear
- Latest research on causes of glue ear
- NICE Clinical Guideline on Surgical management of otitis media with effusion in children - issued February 2008. Detailed, technical, written for healthcare professionals.
- Use and abuse of Evidence Based Medicine
- Grommets, doctors and spin doctors. by JW Fairley and IDB Hore.
All information and advice on this website is of a general nature and may not apply to you. There is no substitute for an individual consultation. We recommend that you see your General Practitioner if you would like to be referred.
|
<urn:uuid:15fed52c-11de-46ed-8970-2142328ad4b7>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-24T08:43:49",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704392896/warc/CC-MAIN-20130516113952-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9288015961647034,
"score": 3.9375,
"token_count": 6813,
"url": "http://entkent.com/glue-ear-grommets-adenoidsmod.html"
}
|
This story comes to us from NBC Latino.
Latino children are currently not enrolled in preschool programs in sufficient numbers, yet a new study finds that equalizing access to center-based preschool could close the Hispanic-white school readiness gap by 26 percent, according to findings in the current issue of The Future of Children, a joint Princeton/Brookings journal. The new issue focuses on “Literacy Challenges for the Twenty-First Century.”
As society becomes more information-based, argue the authors, successful “reading skills” go beyond being able to read technically. ”Almost all U.S. students can ‘read’ by third grade, if reading is defined as being proficient in basic procedural word-reading skills,” say the authors of a chapter on literacy patterns in U.S. children. But when assessing reading comprehension, “only about a third of U.S. students in middle school possess the knowledge-based competencies to ‘read’ in this sense,” the report says.
The Latino-white achievement gap has narrowed in the last few decades, say the researchers. The promising news is that while Latino children with limited English and less access to preschool start out with a Latino-white gap, the gaps narrow or stabilize after a few years. Moreover, in the Latino community, the size of the Hispanic-white gap varies. Reading scores are typically lower for Hispanics of Mexican or Central American origin and for first- or second-generation immigrant students or those who speak Spanish at home than for Cuban or Puerto Rican children or those who speak English at home.
What worries the researchers is that the socioeconomic literacy gap has widened. Students from low-income families enter high school with average literacy skills five years behind those of high-income students, says a chapter on literacy patterns. In fact a Brookings analysis found that if the “academic success rates of lower- and higher-income children were roughly equal at the end of elementary school, the lifetime incomes of children from lower-income families could grow about 8 percent, or roughly $83,000, over their careers.”
Correcting gaps and providing a strong basis for Latino students’ success in literacy and reading comprehension — regardless of socio-economic status — has to start at the lower grades, say the authors. One of the ways to narrow this gap, especially among Latino children, say the authors, is for children from non-English-speaking or low-income households to have access to high-quality pre-schools which provide parental education, home-visiting services, and high-quality center-based education and care.
Columbia University’s Jane Waldfogel and Katherine Magnuson found “equalizing access to center-based preschool, in which Hispanic children are significantly underenrolled, could close as much as 26 percent of the Hispanic-white gaps, with improvements in Head Start closing another 4–8 percent,” saying the role of early childhood education and care was very important in explaining Hispanic-white gaps in school readiness.
Other policy recommendations include improving the content of the reading in the primary grades, so students can learn about current events and start learning comprehension and analyses, teaching subject-specific literacy skills, as well as school reform initiatives, better educational ‘infrastructure’ (more data and curriculum and professional development for teachers), perhaps Common Core State Standards to insure learning goals, and most importantly, programs to attract the top college graduates to become teachers.
“Unless the United States can markedly improve the literacy skills of today’s minority children the labor force of the future will have lower literacy skills than the labor force of today,” say The Future of Children editors and authors.
Sandra Lilley is a reporter with NBC Latino.
All statements and opinions expressed on this blog are those of the individual contributors, and not of the Bill & Melinda Gates Foundation or NBC News.
|
<urn:uuid:0f4f0932-ff68-456e-befa-27f3d6401f86>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-24T08:43:46",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704392896/warc/CC-MAIN-20130516113952-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9523536562919617,
"score": 3.515625,
"token_count": 809,
"url": "http://www.educationnation.com/index.cfm?objectid=CB8FA936-17B7-11E2-A3EB000C296BA163"
}
|
Electrical inductance sensors are non-contact devices that measure the inductance of an electrical component or system. They consist of a wire loop or coils and are relatively inexpensive. Inductance, the property of a circuit or circuit element to oppose a change in current flow, refers to the capacity of a conductor to produce a magnetic field. The standard unit of inductance is the Henry (H). Because the Henry is a large unit, electrical inductance sensors often measure inductance in microhenry (µH) or millihenry (mH) levels.
Electrical inductance sensors contain a nickel-iron core shaft that rotates within the coil around the material. The inductance measured by an electrical inductance sensor depends on the number of turns in the coil, the type of material around which the coil rotates, and the radius of the coil. With the rotation of the shaft, displacement occurs within the coil and generates inductance. This displacement produces signals that can be measured by an inductance meter and recorded. Most inductance meters are digital, hand held devices suitable for measuring inductance of very low value. The results of the inductance calculation can be plotted as a graph for future study.
Selecting electrical inductance sensors requires a careful analysis of product specifications and application requirements. Most electrical inductance sensors have a standard accuracy variance of less than 0.5% when measured on full scale. For best results, an electrical inductance sensor should be able to generate an output signal of at least 4-20 mA. Typically, a sensor’s measurement range is approximately 30% of the coil diameter. For high precision measurements, the thickness of the coil should be at least 0.025 inches (in.).
Electrical inductance sensors are used in many different applications. Some electrical sensors are used in the automotive industry and the power industry. Other electrical sensors are used in constructing planar transformers, generating electrical magnetic fields, and monitoring the inductance of an electrical component. Electrical sensors such as electrical inductance sensors are widely used for detecting the presence of electrical voltage in equipments, and defective grounds.
|
<urn:uuid:bfe63548-3bc5-44fa-be93-553592b82423>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-24T08:44:49",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704392896/warc/CC-MAIN-20130516113952-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.904317319393158,
"score": 4,
"token_count": 433,
"url": "http://www.globalspec.com/learnmore/sensors_transducers_detectors/electrical_electromagnetic_sensing/electrical_inductance_sensors"
}
|
Peripheral Arterial Disease
What Is It?
In peripheral arterial disease (previously called peripheral vascular disease), not enough blood flows to the legs. The condition usually is caused by fatty deposits called plaques that build up along the walls of blood vessels. This buildup shrinks the size of the passageway and reduces the amount of blood that can flow through. This is a condition called atherosclerosis.
The risk factors for getting peripheral arterial disease are similar to the risk factors for coronary heart disease, and include:
- Smoking cigarettes or using other forms of tobacco (such as snuff and chew)
- An abnormally high level of cholesterol (hypercholesterolemia)
- An abnormally low level of high-density lipoprotein (HDL, the good cholesterol)
- High blood pressure (hypertension)
- Family history of cardiovascular disease
- Physical inactivity (too little regular exercise)
- Kidney disease
- Race (blacks appear to have a higher risk of developing the disease)
The most common symptom of peripheral arterial disease is intermittent claudication -- pain or cramping in the legs or buttocks that starts when you exercise and goes away when you rest. Often the pain is described as a deep ache, especially in the calf muscle. The pain may extend to the foot or up toward the thigh and buttock. Sometimes, there is just numbness in the leg or a sense that one leg gets tired when you walk. A foot or toes also may feel cold or numb.
If the arteries are severely narrowed, you could experience leg pain at rest, when you are not exercising. If blood flow stops completely (usually because a blood clot forms in the narrowed vessel), parts of the leg may become pale or turn blue, feel stone cold to the touch and eventually develop gangrene.
Your doctor will review your personal risk factors for atherosclerosis and your family history. Your doctor will ask if you or any family members have heart disease, high cholesterol, diabetes, kidney disease, high blood pressure or any other circulation disorder. During the physical examination, your doctor will feel the pulse in your upper leg (near the groin), on the inside of your ankle, the top of your foot and the back of your knee. Any weakness in a pulse may be a sign of narrowed arteries.
Usually the doctor can diagnose peripheral arterial disease based on your symptoms, risk factors, the examination of your legs and the strength of your pulses. Your doctor may measure the blood pressure in your legs and compare it to the blood pressure in your arm to calculate the ankle-brachial index, or ABI. The ratio the blood pressure measured at your ankle is compared to the blood pressure measured at your elbow. Normally blood pressure is the same or a little higher in the legs so the ratio is 1.0 or higher.
A ratio of less than 0.95 in either leg indicates narrowing of the arteries in that leg. People who have symptoms of peripheral arterial disease usually have a ratio of 0.8 or less.
Your doctor may order ultrasound of the legs to measure blood flow. The test is non-invasive and painless, using sound waves to create the pictures. If your doctor suspects that you need a procedure to help open a blocked blood vessel, you may need a magnetic resonance imaging (MRI) scan of your arteries or an angiogram, which is an X-ray test that uses dye in the narrowed arteries to reveal the pattern of blood flow and spot blockages.
Once you have peripheral arterial disease, your arteries usually will remain narrowed. However, even though your arteries are narrowed, your symptoms can decrease and even go away with treatment.
You can help to prevent peripheral arterial disease by modifying your risk factors:
- Don't smoke. This a major risk factor that you can control.
- Maintain a healthy weight. Obesity, especially a concentration of body fat around the waist, has been linked to unhealthy blood levels of cholesterol and other fats, which can build up inside your arteries.
- Eat a healthy diet. Your diet should be loaded with vegetables and fruits, and it should be low in saturated fats.
- Exercise regularly. Ideally, you should exercise 45 minutes or more every day.
- Lower your blood pressure. Medications may be necessary if maintaining a healthy lifestyle is not enough.
Treatment for peripheral arterial disease includes:
- Modifying risk factors. Quitting smoking can reduce the symptoms of intermittent claudication and decrease the likelihood that the disease will get worse. It is also important to lower your cholesterol levels if they are high, keep blood pressure in the normal range, and keep your diabetes well-controlled. Talk to your doctor about the best way to do this.
- Exercise programs. Studies have shown that people who exercise can nearly double the distance they can walk before they start feeling leg pain. Try to exercise at least 30 minutes every day. You may need frequent breaks if your legs hurt. Even if you have to stop every few minutes, don't give up. Any activity is very beneficial. Most people choose walking, and find that walking on a track or a treadmill is easier than walking on pavement. You could also try bike riding (stationary or standard) and swimming.
- Medications. Even if you exercise and modify your risk factors, medications can help you to better relieve symptoms and may help to slow the progression of the disease. Your doctor probably will advise you to take aspirin every day, or to take another blood-thinning medication, such as clopidogrel (Plavix). Medications, such as cilostazol (Pletal) and pentoxifylline (Trental), also can help to decrease the symptoms of intermittent claudication.
- Revascularization procedures. The goal of revascularization is to improve circulation, either by opening narrowed arteries or by bypassing the narrowed section of the artery. These procedures include surgical and nonsurgical techniques and are used in people who have severe or progressive symptoms, or whose leg pain occurs at rest. The most common nonsurgical procedure is percutaneous transluminal angioplasty, also called balloon angioplasty. In this procedure, a catheter is inserted into the narrowed artery and a small balloon at the tip is inflated to open the narrowed vessel. Often, a metallic implant called a stent is used as a scaffold to support the wall of the artery after it is opened with the balloon. In some people, the narrowed vessel must be bypassed surgically using either a section of vein taken from the leg or a synthetic graft.
When to Call a Professional
Call your doctor if you consistently suffer from cramps, aching, numbness or disproportionate fatigue in your leg muscles or buttocks when you exercise. Call immediately if you have these symptoms at rest or when any part of your leg or foot suddenly turns numb, cold, pale or a bluish color.
In most people with peripheral arterial disease, leg symptoms remain stable. About 10% to 15% of patients improve, and about 15% to 20% get worse. The outlook is better for people who are able to remain tobacco-free, stay on a healthy diet, keep their blood cholesterol under control and exercise regularly.
National Heart, Lung and Blood Institute (NHLBI)
P.O. Box 30105
Bethesda, MD 20824-0105
|
<urn:uuid:05380065-66de-4d22-b1e0-8a9bb7550a9e>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-24T09:06:43",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704392896/warc/CC-MAIN-20130516113952-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.930816113948822,
"score": 3.53125,
"token_count": 1530,
"url": "http://www.intelihealth.com/IH/ihtIH/EMIHC000/9339/35834.html"
}
|
The First (and Last) Voyage to the Bottom of the Sea
A half-century ago, humanity arrived somewhere no one had ever gone before the deepest place on Earth.
Before the Apollo missions landed men on the moon, the U.S. Navy dove to the bottom of the sea the Challenger Deep in the Mariana Trench, some 35,797 feet (10,911 meters) down.
Just as no one has visited the moon since Apollo, nobody has returned to this abyss since that first voyage to the bottom of the trench in 1960. However, just as scientists are revisiting the moon with space probes, so too are researchers now deploying robots to explore this deepest depth of the ocean .
The research vessel used to reach the record-setting depth near Guam in the Pacific Ocean on Jan. 23, 1960 was named the Trieste, a Swiss-designed bathyscaphe or "deep boat" named after the Italian city where much of it was built. Its two-man crew Lt. Don Walsh of the U.S. Navy and scientist Jacques Piccard, son of the craft's designer nestled inside a roughly 6.5-foot (2-meter) wide white pressure sphere on the underside of the submersible. The rest of the nearly 60-foot (18-meter)long Trieste was filled with floats loaded with some 33,350 gallons (126,243 liters) of gasoline for buoyancy, along with nine tons of iron pellets to weigh it down.
To withstand the high pressure at the bottom of Challenger Deep roughly eight tons per square inch the sphere's walls were 5 inches (12.7 cm) thick. To see outside, the crew relied on a window made of a single cone-shaped block of Plexiglas, the only transparent compound they could find strong enough to survive the pressure at the thickness needed, along with lamps to light up the sunless abyss.
"The pressure is tremendous," said geophysicist David Sandwell at the University of California, San Diego, who helped create the first detailed global maps of the seafloor.
The descent the first and only manned voyage to the bottom of Challenger Deep took 4 hours and 48 minutes at a rate of about a yard (0.9 meters) a second. As if to highlight the dangers of the dive, after passing about 27,000 feet (9,000 meters) one of the outer window panes cracked, violently shaking the entire vessel.
The two men spent just 20 minutes at the ocean floor, eating chocolate bars for energy in the cold deep, the temperature in the cabin was only 45 degrees Fahrenheit (7 degrees Celsius). They actually managed to speak with the craft's mothership using a sonar-hydrophone system at a speed of nearly a mile per second, it still took about seven seconds for a voice message to travel from the craft upward.
While at the bottom, the explorers not only saw jellyfish and shrimp-like creatures, but actually spied a couple of small white flatfish swimming away, proving that at least some vertebrate life could withstand the extremes of the bottom of the ocean. The floor of Challenger Deep seemed to be made of diatomaceous ooze a fine white silt made of microscopic algae known as diatoms.
To ascend, they magnetically released the ballast, a trip that took 3 hours, 15 minutes. Since then, no man has ever returned to Challenger Deep.
"It's hard to build something that can survive that kind of pressure and have people inside," Sandwell noted.
In many ways, the Trieste laid the foundation for the Navy's deep-submergence program. In fact, in 1963, it was used to locate the sunken nuclear submarine USS Thresher.
In addition, in recent years, robots have made the journey back to Challenger Deep. In 1995, the Japanese craft Kaiko reached the bottom, while the Nereus hybrid remotely operated vehicle reached the bottom last year.
Perhaps as explorers one day hope to return to the moon, so too might adventurers, and not just robots, revisit the deeps in the future.
- The World's Biggest Oceans and Seas
- Infographic: Under the Ocean's Surface
- World's Deepest Undersea Vents Discovered
MORE FROM LiveScience.com
|
<urn:uuid:1cfec21c-f34f-4a68-b967-6109f33f8afc>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-24T08:44:31",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368704392896/warc/CC-MAIN-20130516113952-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9447028636932373,
"score": 3.9375,
"token_count": 889,
"url": "http://www.livescience.com/29534-the-first-and-last-voyage-to-the-bottom-of-the-sea.html"
}
|
Dinosaurs' active lifestyles suggest they were warm-blooded
H. Pontzer, V. Allen, J.R. Hutchinson/PLoS ONE
Whether dinosaurs were warm-blooded or cold-blooded has been a long-standing question in paleobiology. Now, new research on how two-legged dinosaurs walked and ran adds new evidence to the argument for warm-bloodedness, and suggests that even the earliest dinosaurs may have been warm-blooded.
Warm-blooded (or endothermic) dinosaurs — able to regulate their own body temperatures — would have been more active and could have inhabited colder climates than cold-blooded (or ectothermic) dinos, which would have functioned more like modern reptiles — animals that become animated only as temperatures warm. Endothermic dinosaurs would have also required more energy to maintain their higher metabolic rates. Evidence such as rapidly growing bones, bird-like feathers and athletic builds have led most paleontologists to believe that dinosaurs were endothermic, says paleobiologist Greg Erickson of Florida State University in Tallahassee, Fla., who was not involved in the new research.
But many scientists are still averse to the idea of warm-blooded dinosaurs. For example, some researchers have suggested that larger, more massive dinosaurs may have radiated much less heat than smaller dinosaurs — and thus, they could have been cold-blooded while still able to maintain relatively high body temperatures.
In the new study, published today in PLoS ONE, biomechanist Herman Pontzer of Washington University in St. Louis, Mo., and colleagues sought to figure out whether the lower metabolism of an ectotherm would have afforded dinosaurs the energy they needed to walk and run. To test this possibility, the team looked at two factors thought to be linked with energy requirements in modern animals: hip height and the volume of muscle used to hold up and move an animal’s body forward. If the limb length and active muscle volumes of dinosaurs required more energy than an ectotherm’s metabolism would have been able to provide, Pontzer and colleagues reasoned, then the dinosaurs were likely endothermic.
The team studied 13 different two-legged dinosaur species, ranging in size from Tyrannosaurus to the tiny, bird-like Archaeopteryx, as well as one early dinosaur relative, Marasuchus. Based on hip height, the results showed that the five largest dinosaurs (including Tyrannosaurus) would have needed endothermic metabolisms just to have the energy to walk, and all of the dinosaurs would have required endothermy to run at a moderate speed. Results based on estimated active muscle volume revealed a similar pattern: The five largest dino species would have needed to be endothermic to walk or run, while smaller, very active dinosaurs such as Velociraptor, must have been endothermic to be able to run.
In addition, even the most ancient dinosaur-like relative, Marasuchus, may have been endothermic based on the data from the hip study, Pontzer says, suggesting that endothermy evolved very early on in the dinosaur lineage. Therefore, the results also suggest that all dinosaurs were endothermic, the team wrote.
“I think their study is pointing to what a lot of other studies are saying — that these animals were endothermic,” Erickson says. “It’s just, what grade of endothermy were we dealing with?” For example, modern marsupials, although endothermic, generally grow more slowly and have lower metabolic rates than other mammals, he says.
The study may not put the final "nail in the coffin" for the idea that large dinosaurs could have been ectothermic, but it does provide positive evidence for an alternative metabolic strategy, says Patrick O’Connor, a paleontologist at the Ohio University College of Osteopathic Medicine in Athens who was also not involved in the new research. "Studies like this add crucial new lines of evidence that help us refine existing hypotheses," O'Connor says.
Estimating dinosaur metabolisms based on modern animals can only go so far, according to Erickson. For example, Pontzer and colleagues focused on two-legged dinosaurs because if they had used four-legged dinosaurs, they would have also needed to estimate how the dinosaurs’ weight was distributed across all four legs.
But because all modern ectotherms, such as alligators, are four-legged, Pontzer and colleagues had to gauge the hypothetical ectothermic capacity for the two-legged dinosaurs against four-legged modern animals, Erickson notes. Moreover, even the largest modern ectotherms are much smaller than a 6-metric-ton Tyrannosaurus. “There are limitations from living organisms that make it so we may never be able to test all these ideas,” Erickson says.
Still, Erickson says he thinks scientists are “honing in on the real answer” on the question of when endothermy evolved in dinosaurs and other ancient vertebrates. Other evidence, such as rates of bone growth, suggests pterosaurs, or flying reptiles, were also endothermic. “When you have all these different lines of evidence kind of pointing towards [endothermy],” he says, “I think it’s fairly compelling collectively.”
|
<urn:uuid:a459a3fc-e2ca-4318-b2d2-359bd270ce2f>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-06-18T22:39:32",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368707435344/warc/CC-MAIN-20130516123035-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9630212783813477,
"score": 4.40625,
"token_count": 1101,
"url": "http://www.earthmagazine.org/article/dinosaurs-active-lifestyles-suggest-they-were-warm-blooded"
}
|
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2007 October 24
Explanation: Scroll right and cruise above the thin, icy rings of Saturn. This high resolution scan is a mosaic of images presented in natural color and recorded in May, over about 2.5 hours as the Cassini spacecraft passed above the unlit side of the rings. The rings themselves are seen to be composed of many individual ringlets. To help track your progress, the rings are labeled below, along with the distance from the center of the gas giant in kilometers. Major ring gaps are labeled above. The alphabetical designation of Saturn's rings is historical and related to their order of discovery; rings A and B are the bright rings separated by the Cassini division. In order of increasing distance from Saturn, the seven main rings run D,C,B,A,F,G,E. (Faint, outer rings G and E are not imaged here.)
Authors & editors:
Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
A service of: ASD at NASA / GSFC
& Michigan Tech. U.
|
<urn:uuid:c5258daa-898f-43d7-8409-e88c113b91cf>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-19T10:03:25",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368697380733/warc/CC-MAIN-20130516094300-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9151161909103394,
"score": 3.5625,
"token_count": 254,
"url": "http://apod.nasa.gov/apod/ap071024.html"
}
|
In the cities and countryside section of Busy Teacher, there are 78 FREE worksheets to choose from
. They range from very simple word searches to detailed activities related to these topics. This activity
, for example, was created for Russian ESL learners but can serve as a model for you to create a similar activity more appropriate for your students. Some nice details on this worksheet include the translations of important words, the colorful images, and the fact that after completing this exercise, students should be able to create a similar article about the town they live in. You could do this as a class, in groups, or individually depending on your students and class size. Take a look at other worksheets to find something your students will enjoy.
It is good to talk about different places, compare them, and be able to describe them to people. Students will enjoy sharing their views of certain locations and some will certainly feel very strongly about cities while others will prefer the countryside. This division could set you up for a debate about the positive and negative characteristics of each. Despite your personal opinion, try to remain neutral and simply facilitate the discussion. This is just one way to incorporate this topic into your lessons.
|
<urn:uuid:f96e5d95-4d79-4709-bf16-5ebd19b0893e>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-19T09:54:19",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368697380733/warc/CC-MAIN-20130516094300-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9619055390357971,
"score": 4.375,
"token_count": 243,
"url": "http://busyteacher.org/classroom_activities-vocabulary/city_and_countryside-worksheets/"
}
|
RNA, ribonucleotide acid, is built up of a phosphate and nitrogenous base, a ribose sugar, and a phosphate. The bases used are adenine (A), cytosine (C), guanine (G) and uracil (U).
The chemical structure of RNA
There are four major groups of RNA: messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA) and small, regulatory RNAs (sRNA). mRNA is transcribed from DNA by the enzyme RNA polymerase, and is then used as a template in translation. rRNAs are a major component of the ribosome, the translation machinery. They are divided into the 50S large subunit (23S and 5S) and small 30S (16S) in prokaryotes. The rRNAs decode the mRNA and interact with tRNAs. The tRNAs are attached to specific amino acids and carry them (with the help of elongation factor Tu) to the ribosome during translation. The sRNAs form a quite recently discovered group of regulatory RNAs that are thought to be of great importance especially during stress, when they bind specifically to their targets and as a consequence effect the expression of genes, either at the level of transcription or translation.
|
<urn:uuid:f44e2793-140c-4216-818a-97021b96f284>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-19T09:53:59",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368697380733/warc/CC-MAIN-20130516094300-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9470864534378052,
"score": 3.90625,
"token_count": 271,
"url": "http://wiki.biomine.skelleftea.se/wiki/index.php/RNA"
}
|
Interrupt the execution of an expression and allow the inspection of the environment where
browser was called from.
browser(text = "", condition = NULL, expr = TRUE, skipCalls = 0L)
- a text string that can be retrieved once the browser is invoked.
- a condition that can be retrieved once the browser is invoked.
- An expression, which if it evaluates to
TRUEthe debugger will invoked, otherwise control is returned directly.
- how many previous calls to skip when reporting the calling context.
A call to
browser can be included in the body of a function. When reached, this causes a pause in the execution of the current expression and allows access to the R interpreter.
The purpose of the
condition arguments are to allow helper programs (e.g. external debuggers) to insert specific values here, so that the specific call to browser (perhaps its location in a source file) can be identified and special processing can be achieved. The values can be retrieved by calling
The purpose of the
expr argument is to allow for the illusion of conditional debugging. It is an illusion, because execution is always paused at the call to browser, but control is only passed to the evaluator described below if
expr evaluates to
TRUE. In most cases it is going to be more efficient to use an
if statement in the calling program, but in some cases using this argument will be simpler.
skipCalls argument should be used when the
browser() call is nested within another debugging function: it will look further up the call stack to report its location.
At the browser prompt the user can enter commands or R expressions, followed by a newline. The commands are
- (or just an empty line, by default) exit the browser and continue execution at the next statement.
- synonym for
- enter the step-through debugger if the function is interpreted. This changes the meaning of
c: see the documentation for
debug. For byte compiled functions
nis equivalent to
- print a stack trace of all active function calls.
- exit the browser and the current evaluation and return to the top-level prompt.
(Leading and trailing whitespace is ignored, except for an empty line).
Anything else entered at the browser prompt is interpreted as an R expression to be evaluated in the calling environment: in particular typing an object name will cause the object to be printed, and
ls() lists the objects in the calling frame. (If you want to look at an object with a name such as
n, print it explicitly.)
The number of lines printed for the deparsed call can be limited by setting
TRUE disables the use of an empty line as a synonym for
c. If this is done, the user will be re-prompted for input until a valid command or an expression is entered.
This is a primitive function but does argument matching in the standard way.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Chambers, J. M. (1998) Programming with Data. A Guide to the S Language. Springer.
Documentation reproduced from R 2.15.3. License: GPL-2.
|
<urn:uuid:a0f6a31d-26d9-465a-85af-fcef7ca88935>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-19T10:04:47",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368697380733/warc/CC-MAIN-20130516094300-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.8091210722923279,
"score": 3.84375,
"token_count": 690,
"url": "http://www.inside-r.org/r-doc/base/browser"
}
|
Science Fair Project Encyclopedia
Flag of the United States
The flag of the United States of America consists of thirteen equal horizontal stripes of red (top and bottom) alternating with white; there is a blue rectangle in the upper hoist-side corner bearing 50 small, white, five-pointed stars arranged in nine offset horizontal rows of six stars (top and bottom) alternating with rows of five stars. The 50 stars on the flag represent the 50 states and the 13 stripes represent the 13 original colonies.
The United States flag is commonly called the Stars and Stripes and less commonly Old Glory. The name Old Glory was coined in the 1830s, and was of particularly common use during the era of 48-star version (1912 to 1959).
4.1 Standards of respect
While institutions often display the flag year-round, most homeowners reserve flag display for civic holidays like Memorial Day, Veteran's Day, Presidents' Day, Flag Day and the Fourth of July. On Memorial Day it is common to place small flags by war memorials and next to the graves of U.S. war dead.
To some U.S. citizens, their flag symbolizes many things. They have seen it as representing all of the freedoms and rights guaranteed in the U.S. Constitution and its Bill of Rights. Perhaps most of all they see it as a symbol of individual and personal liberty like those put forth in the U.S. Declaration of Independence.
The approved method of destroying old and tattered flags consists of burning them in a simple ceremony. The flag is cut into three pieces: first a horizontal cut is made between the seventh and eighth stripes, then a vertical cut separating the star field from the seven shorter stripes. Then the three pieces are typically placed on a pyre as 'Taps' is played. Burning the flag has also been used as a deliberate act of disrespect, at times to protest actions by the United States government, or sometimes in displays of Anti-Americanism. Some groups concerned by these actions have proposed a Flag Burning Amendment that would outlaw burning the flag in disrespect or protest.
Flags with similar design
Flags from other countries share, at varying degrees, the design and/or color scheme of the United States flag. Several of the flags of the Confederate States of America also reflect the colors and design of the Stars and Stripes. Some examples of national flags sharing elements of the U.S. flag include:
There are certain guidelines for the use and display of the United States flag as outlined in the United States Flag Code of the federal government. It should be stressed that these are guidelines, not laws, which lack a penalty for those who fail to comply with them.
Standards of respect
- The flag should never be dipped to any person or thing.
- The flag is flown upside down only as a distress signal.
- The flag should not be used as a drapery, or for covering a speakers desk, draping a platform, or for any decoration in general. Bunting of blue, white and red stripes is available for these purposes. The blue stripe of the bunting should be on the top.
- The flag should never be drawn back or bunched up in any way.
- The flag should never be used as a covering for a ceiling.
- The flag should never be used for any advertising purpose. It should not be embroidered, printed or otherwise impressed on such articles as cushions, handkerchiefs, napkins, boxes or anything intended to be discarded after temporary use. Advertising signs should not be attached to the staff or halyard.
- The flag should not be used as part of a costume or athletic uniform, except that a flag patch may be used on the uniform of military personnel, fireman, policeman and members of patriotic organizations.
- The flag should never have placed on it, or attached to it, any mark, insignia, letter, word, number, figure, or drawing of any kind.
- The flag should never be used as a receptacle for receiving, holding, carrying, or delivering anything.
- The flag should not be draped over the hood, top, sides, or back of a vehicle, railroad train or boat.
- When the flag is lowered, no part of it should touch the ground or any other object; it should be received by waiting hands and arms. To store the flag it should be folded neatly and ceremoniously.
- The flag should be cleaned and mended when necessary.
- When a flag is so worn it is no longer fit to serve as a symbol of the United States, it should be destroyed in a dignified manner, preferably by burning. (Note: Most American Legion Posts regularly conduct a dignified flag burning ceremony, often on Flag Day, June 14.)
Contrary to a commonly believed urban legend, the flag code does not state that a flag which touches the ground should be burned. Instead, the flag should be moved so it is not touching the ground.
Displaying the flag outdoors
- When the flag is displayed from a staff projecting from a window, balcony, or a building, the union should be at the peak of the staff unless the flag is at half staff. When it is displayed from the same flagpole with another flag, the flag of the United States must always be at the top except that the church pennant may be flown above the flag during church services for Navy personnel when conducted by a Naval chaplain on a ship at sea.
- When the flag is displayed over a street, it should be hung vertically, with the union to the north or east. If the flag is suspended over a sidewalk, the flag's union should be farthest from the building.
- When flown with flags of states, communities or societies on separate flag poles which are of the same height and in a straight line, the flag of the United States is always placed in the position of honor—to its own right. The other flags may be smaller but none may be larger.
- No other flag ever should be placed above it. The flag of the United States is always the first flag raised and the last to be lowered.
- When flown with the national banner of other countries, each flag must be displayed from a separate pole of the same height. Each flag should be the same size. They should be raised and lowered simultaneously. The flag of one nation may not be displayed above that of another nation.
- The flag should be raised briskly and lowered slowly and ceremoniously.
- Ordinarily it should be displayed only between sunrise and sunset. (By Presidential proclamation and law, the flag is displayed continuously at certain honored locations like the United States Marine Corps Memorial in Arlington and Lexington Green.)
- It should be illuminated if displayed at night.
- The flag of the United States of America is saluted as it is hoisted and lowered. The salute is held until the flag is unsnapped from the halyard or through the last note of music, whichever is the longest.
Displaying the flag indoors
- When on display, the flag is accorded the place of honor, always positioned to its own right. Place it to the right of the speaker or staging area or sanctuary. Other flags should be to the left.
- The flag of the United States of America should be at the center and at the highest point of the group when a number of flags of states, localities, or societies are grouped for display.
- When one flag is used with the flag of the United States of America and the staffs are crossed, the flag of the United States is placed on its own right with its staff in front of the other flag.
- When displaying the flag against a wall, vertically or horizontally, the flag's union (stars) should be at the top, to the flag's own right, and to the observer's left.
Parading and saluting the flag
- When carried in a procession, the flag should be to the right of the marchers.
- When other flags are carried, the flag of the United States may be centered in front of the others or carried to their right. When the flag passes in a procession, or when it is hoisted or lowered, all should face the flag and salute.
- To salute, all persons come to attention.
- Those in uniform give the appropriate formal salute.
- Citizens not in uniform salute by placing their right hand over the heart and men with head cover should remove it and hold it to left shoulder, hand over the heart.
- Members of organizations in formation salute upon command of the person in charge.
Pledge of Allegiance and national anthem
- The Pledge of Allegiance should be rendered by standing at attention, facing the flag, and saluting.
- When the national anthem is played or sung, citizens should stand at attention and salute at the first note and hold the salute through the last note. The salute is directed to the flag, if displayed, otherwise to the music.
The flag, in mourning
- To place the flag at half-staff (or half-mast, on ships), hoist it to the peak for an instant and lower it to a position half way between the top and bottom of the staff.
- The flag is to be raised again to the peak for a moment before it is lowered.
- On Memorial Day, the flag is displayed at half-staff until noon and at full staff from noon to sunset.
- The flag is to be flown at half-staff in mourning for designated, principal government leaders and upon presidential or gubernatorial order.
- The U.S. flag is otherwise flown at half-staff (or half-mast, on ships) when directed by the President of the United States or a state governor.
- When used to cover a casket, the flag should be placed with the union at the head and over the left shoulder. It should not be lowered into the grave.
Folding the flag
Flags, when not in use, should be folded into a triangle shape. The final triangle shape result is said to invoke the image of the three-point hats popular during the American Revolutionary War. Former American territories, e.g. the Philippines, also use this method to fold their flags.
- To properly fold the flag, begin by holding it waist-high with another person so that its surface is parallel to the ground.
- Fold the lower half of the stripe section lengthwise over the field of stars, holding the bottom and top edges securely.
- Fold the flag again lengthwise with the blue field on the outside.
- Make a triangular fold by bringing the striped corner of the folded edge to meet the open top edge of the flag.
- Turn the outer end point inward, parallel to the open edge, to form a second triangle.
- The triangular folding is continued until the entire length of the flag is folded in this manner.
- When the flag is completely folded, only a triangular blue field of stars should be visible.
Places where the American flag is displayed continuously
According to Presidential proclamation and in some cases, U.S. law, the American flag is displayed continuously at the following locations:
- Mount Slover limestone quarry, in Colton, California (Act of Congress). First raised July 4, 1917.
- Fort McHenry National Monument and Historic Shrine, Baltimore, Maryland (Presidential Proclamation No. 2795, July 2, 1948).
- Flag House Square , Albemarle and Pratt Streets, Baltimore, Maryland (Public Law 83-319, approved March 26, 1954).
- United States Marine Corps Memorial (Iwo Jima), Arlington, Virginia (Presidential Proclamation No. 3418, June 12, 1961).
- Lexington, Massachusetts Town Green (Public Law 89-335, approved November 8, 1965).
- The White House, Washington, DC (Presidential Proclamation No.4000, September 4, 1970).
- Fifty U.S. Flags are displayed continuously at the Washington Monument, Washington, DC. (Presidential Proclamation No. 4064, July 6, 1971, effective July 4, 1971).
- United States Customs Service Ports of Entry that are continuously open (Presidential Proclamation No.4131, May 5, 1972).
- Grounds of the National Memorial Arch in Valley Forge State Park, Valley Forge, Pennsylvania (Public Law 94-53, approved July 4, 1975).
- In addition, the American flag is presumed to be in continual display on the surface of the Earth's Moon, having been placed there by the astronauts of Apollo 11. It is assumed however that the flag was knocked down by the force of Apollo 11's return to lunar orbit.
The flag has gone through 26 changes since the new union of 13 states first adopted it. The 48-star version holds the record, 47 years, for the longest time the flag has gone unchanged. The current 50-star version will tie the record if it is still in use on July 4, 2007.
At the time of the signing of the Declaration of Independence, July 4th, 1776, the most commonly flown flag was the Grand Union Flag. This flag was initially flown by George Washington and is recorded as being first raised by Washington's troops at Prospect Hill on New Year's Day in 1776. This flag formed the basis of the Stars and Stripes, consisting of 13 red and white stripes with the British Union Jack in the canton.
On June 14, 1777, the Second Continental Congress passed the Flag Resolution which stated: "Resolved, That the flag of the United States be made of thirteen stripes, alternate red and white; that the union be thirteen stars, white in a blue field, representing a new Constellation." Describing the new flag, the Congress wrote, "White signifies Purity and Innocence; Red, Hardiness and Valor; Blue signifies Vigilance, Perseverance and Justice." Flag Day is now observed on June 14 of each year.
The Flag Resolution did not specify any particular arrangement for the stars. Initially, a variety of designs were used, including a circular arrangement (above left), but gradually a design featuring horizontal rows of stars emerged as the standard. As further states entered the union, extra stars and stripes were added until this proved to cause too much clutter. It was ultimately decided that there would be a star for each state, but the number of stripes would remain at thirteen to honor the original colonies. It was the 15-star, 15-stripe flag that inspired Francis Scott Key to write "The Star-Spangled Banner", now the national anthem.
When the flag design changes, the change always takes place on July 4 in Philadelphia, Pennsylvania, as a consequence of the Flag Act of April 4, 1818. July 4, Independence Day in the United States, commemorates the founding of the nation. The most recent change, from forty-nine stars to fifty, occurred in 1960, after Hawaii gained statehood in August 1959. Before that, the admission of Alaska in January 1959 prompted the debut of a short-lived 49-star flag.
The origin of the U.S. flag design is uncertain. A popular story credits Betsy Ross for sewing the first flag from a pencil sketch of George Washington who personally commissioned her for the job. However, no evidence for this theory exists beyond Ross's own records. The British historian Sir Charles Fawcett has suggested that the design of the flag may have been derived from the flag and jack of the British East India Company. Comparisons between the 2 flags support Fawcett's suggestion. Another popular theory is that the flag was designed by Francis Hopkinson. He reportedly originally wanted the stars arranged in four bands, one vertical, one horizontal, and two diagonal. By the same reports, this arrangement was rejected due to similarity to the British flag.
Historical star patterns
On the current 50-star flag, the width (fly) of the blue rectangle is 76% of the height (hoist) of the whole flag, and its height is 7 of the 13 stripes.
Note that the following star patterns are merely the usual patterns, with the exception of the 48-, 49-, and 50-star flags, as there was no official arrangement of the stars until the proclamation of the 48-star flag by President William Howard Taft in 1912. For alternate versions, see this page at Flags of the World
13 (1776) Betsy Ross flag
50 (1960 - present) Modern Flag
Proposed 51-star flag in case of a future state
Patterns and Symmetry
- symmetry with respect to horizontal axis: 50, 49, 48, 46, 44, 38, 37, 36, 34, 33, 32, 30, 28, 26, 24, 20, 15, 13 (standard)
- symmetry with respect to vertical axis: 51, 50, 48, 46, 45, 44, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 21, 20, 15, 13 (standard and Betsy Ross)
- both, hence also point symmetry: 50, 48, 46, 44, 37, 36, 34, 33, 32, 30, 28, 26, 24, 20, 15, 13 (standard and Betsy Ross)
- no symmetry: 43
- chessboard pattern: 51, 50, 49, 45, 15, 13 (standard)
- rectangle of stars: 48, 35, 30, 28, 24, 20
There are ongoing statehood movements in Puerto Rico, the District of Columbia, and New York City. Other insular areas such as the U.S. Virgin Islands and American Samoa may eventually become states as well.
- Flags of the U.S. states
- Flags of the United States armed forces
- Flags of the Confederate States of America
- Flag desecration in the United States
- United States Army Colors
- U.S. Flag Etiquette
- The United States Flag Page
- Encyclopedia Smithsonian: Facts About the United States Flag
- The Flag Code--U.S. Code Home: Title 4, Flag and Seal, Seat of Government, and the States--Chapter 1, The Flag
- Executive Order No. 10798, with specifications and regulations for the current flag
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details
|
<urn:uuid:c74b5654-0b8f-459c-98c5-6834b9627124>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-22T07:20:38",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368701459211/warc/CC-MAIN-20130516105059-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9232320189476013,
"score": 3.734375,
"token_count": 3818,
"url": "http://all-science-fair-projects.com/science_fair_projects_encyclopedia/Flag_of_the_United_States"
}
|
Splash (fluid mechanics)
In fluid mechanics, a splash is a sudden disturbance to the otherwise quiescent free surface of a liquid (usually water). The disturbance is typically caused by a solid object suddenly hitting the surface, although splashes can occur in which moving liquid supplies the energy. This use of the word is onomatopoeic.
Splashes are characterized by transient ballistic flow, and are governed by the Reynolds number and the Weber number. In the image of a brick splashing into water to the right, one can identify freely moving airborne water droplets, a phenomenon typical of high Reynolds number flows; the intricate non-spherical shapes of the droplets show that the Weber number is high. Also seen are entrained bubbles in the body of the water, and an expanding ring of disturbance propagating away from the impact site.
Physicist Lei Xu and coworkers at the University of Chicago discovered that the splash due to the impact of a small drop of ethanol onto a dry solid surface could be suppressed by reducing the pressure below a specific threshold. For drops of diameter 3.4 mm falling through air, this pressure was about 20 kilopascals, or 0.2 atmosphere.
Splash plate
A plate made of a hard material on which a stream of liquid is designed to fall is called a "splash plate". It may serve to protect the ground from erosion by falling water, such as beneath an artificial waterfall or water outlet in soft ground. Splash plates are also part of spray nozzles, such as in irrigation sprinkler systems.
See also
- Harold Eugene Edgerton, whose Milkdrop Coronet is arguably the most famous photograph of a splash
- Slosh, other free surface phenomenon
- Lei Xu et al., "drop splashing on a dry smooth surface", Phys. Rev. Letts. (2005)
|
<urn:uuid:4c6631d4-811f-4f47-be0c-a0d12013f51d>
|
{
"dataset": "HuggingFaceTB/smollm-corpus",
"date": "2013-05-22T07:41:04",
"dump": "CC-MAIN-2013-20",
"file_path": "s3://commoncrawl/crawl-data/CC-MAIN-2013-20/segments/1368701459211/warc/CC-MAIN-20130516105059-00000-ip-10-60-113-184.ec2.internal.warc.gz",
"int_score": 4,
"language": "en",
"language_score": 0.9331628680229187,
"score": 3.890625,
"token_count": 383,
"url": "http://en.wikipedia.org/wiki/Splash_(fluid_mechanics)"
}
|
End of preview. Expand
in Data Studio
No dataset card yet
- Downloads last month
- 167