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In this section, you will learn how to use Left Shift "<<"
operator in Java. The Java programming language has operators that perform bitwise operations. In the example below we have shown the usage of
Left Shift "<<"
Description of code:
The Left Shift "<<" operator shifts the left operand to the left side by the number of bits specified by its right operand. This operator never throws an exception. Each operand of the left shift operator must be an integer data type otherwise a compile-time error will occur. The following example shows displays the code of left shift operator.
Here is the code of program:
Output of the program:
-9 << 3 = -72
9 << 3 = 72
If you are facing any programming issue, such as compilation errors or not able to find the code you are looking for.
Ask your questions, our development team will try to give answers to your questions. | <urn:uuid:57333e21-938b-4a12-9566-8c5f8223c1dc> | 4.0625 | 194 | Tutorial | Software Dev. | 51.31575 |
Table of Contents
pthread_join - wait for termination of another thread
int pthread_join(pthread_t th, void **thread_return);
pthread_join suspends the execution of the calling thread until the thread identified by th terminates, either by calling pthread_exit(3) or by being cancelled.
If thread_return is not NULL, the return value of th is stored in the location pointed to by thread_return. The return value of th is either the argument it gave to pthread_exit(3) , or PTHREAD_CANCELED if th was cancelled.
The joined thread th must be in the joinable state: it must not have been detached using pthread_detach(3) or the PTHREAD_CREATE_DETACHED attribute to pthread_create(3) .
When a joinable thread terminates, its memory resources (thread descriptor and stack) are not deallocated until another thread performs pthread_join on it. Therefore, pthread_join must be called once for each joinable thread created to avoid memory leaks.
At most one thread can wait for the termination of a given thread. Calling pthread_join on a thread th on which another thread is already waiting for termination returns an error.
pthread_join is a cancellation point. If a thread is cancelled while suspended in pthread_join, the thread execution resumes immediately and the cancellation is executed without waiting for the th thread to terminate. If cancellation occurs during pthread_join, the th thread remains not joined.
On success, the return value of th is stored in the location pointed to by thread_return, and 0 is returned. On error, a non-zero error code is returned.
Xavier Leroy <Xavier.Leroy@inria.fr>
pthread_exit(3) , pthread_detach(3) , pthread_create(3) , pthread_attr_setdetachstate(3) , pthread_cleanup_push(3) , pthread_key_create(3) .
Table of Contents | <urn:uuid:b470d1c9-8203-4ffe-bbc1-81e8c6cdb729> | 3.25 | 452 | Documentation | Software Dev. | 48.112505 |
The College of Literature Science and the Arts (LS&A for short) recently instituted “theme semesters.” For Fall 2005, the theme was “100 Years Beyond Einstein” (2005 is the hundredth anniversary of Einstein’s miraculous year, which I’ll explain below). There were classes, lectures and other events connected with Einstein. One of the lectures, “What Astronomy Has Done For Einstein,” was given by Dr. Joceyln Bell-Burnell.
Joceyln Bell-Burnell was born Susan Jocelyn Bell. Her PhD work involved a then recently discovered class of objects known as quasars. In the late 60’s she and her advisor Antony Hewish used radio telescopes to study quasars. She noticed some signals that repeated with a regular pattern, but no one knew how they were generated.
As a joke, the signals were given the label “Little Green Man 1” (since no one knew what they were, perhaps they were from extra-terrestrials). Soon it was realized it could be explained by a natural process: a new type of object, called a pulsar, was responsible.
Shortly after this discovery she married Martin Burnell, and now uses the name Joceyln Bell-Burnell.
In 1974, Hewish along with Sir Martin Ryle, were awarded the Nobel Prize in Physics in part because of the role Hewish played in the discovery of pulsars. Many people (myself included) believe that Bell-Burnell should have been included in the 1974 award. Nevertheless, Bell-Burnell has received many other awards including the the Michelson Medal of the Franklin Institute.
Dr. Bell-Burnell began her talk with Einstein. Einstein was born in Germany in 1879, but renounced his German citizenship in 1896. He graduated from a Swiss university in the year 1900. He was a man without a country until 1901 when he was granted Swiss citizenship. He had trouble getting a job, but found a position at the Patent Office in Bern, Switzerland. He worked there for several years including the miraculous year 1905. That year Einstein wrote five papers. In chronological order:
(Ok, I just lied, there actually was a sixth paper, but it really was just an elaboration of earlier work).
Before I continue, I must make an important distinction. “The Theory of Relativity” is really two different theories: Special Relativity and General Relativity. Special Relativity was developed during 1905; it is covered in part in “On the Electrodynamics...” and in part in “Does the Inertia of a Body....” The later paper, in three short pages, has all of the thinking necessary to derive E=mc2, however the equation itself did not appear in print until later. Ten years later Einstein developed a different theory called General Relativity. I’ll get to General Relativity in a moment.
“A New Determination...” and “On the Motion...” deal with atoms and molecules. Before these papers there was some doubt about the existence of atoms, after these papers were published and accepted there was no doubt. “A New Determination...” was submitted to the University of Zurich and Einstein was granted a PhD based on that paper.
Some years earlier experimenters noticed that light shining on metal often created an electric current, this became known as the photoelectric effect; but a theory that completely explained it did not exist until “On a Heuristic Point of View...” appeared. Before that paper, physicists believed that light propagated as waves. This paper shows that light propagates as particles. (Einstein initially referred to these particles by the term “quanta of light,” but we now call these particles “photons.” A hundred years later, our understanding of light is more complicated, light is neither a particle nor a wave, but it sometimes behaves like a particle and sometimes it behaves like a wave).
The rest of the talk has nothing to do with these papers.
Special Relativity only describes objects moving in a straight line with constant velocity. Einstein knew that Special Relativity was incomplete.
Einstein returned to Germany in 1914, but did not reapply for German citizenship. He accepted a research position at the University of Berlin. At the time, the best theory of gravity was based on Newton’s laws. But Einstein had problems with it. Over the next couple years, he developed General Relativity, his theory of gravity. General Relativity makes predictions that are similar to Newton’s equations, but there are slight differences. It also involves mathematics that is more complicated than either Newton’s equations or any of Einstein’s 1905 work. Many of the equations of Special Relativity involve simple algebra, this is not true of General Relativity.
This work was finally published in 1916. While the 1905 work was a major accomplishment, other scientists probably could have replicated it if Einstein hadn’t done the work first. It is hard to imagine who would have invented General Relativity if Einstein hadn’t.
1916 was the middle of World War I; Britain was on one side and Germany was on the other. Most British hated the Germans and everything associated with Germany. Dr. Bell-Burnell gave several examples of how this hatred expressed itself, such as the vandalism of stores with German names.
One English astronomer, Arthur Eddington, didn’t participate in this hatred. Eddington was the Secretary of the Royal Astronomical Society and part of his responsibilities was evaluating incoming papers to be published. Einstein’s work on General Relativity was one of these papers. The paper was clearly identified with the University of Berlin, other scientists would have seen such a paper and discarded it along with anything else German. Eddington did not discard the paper, he read it and after he grasped the theory, he explained it to other astronomers and to the general public. Eddington was well respected and good at communicating. Without Eddington’s help, it would have been much longer before Einstein’s ideas gained recognition.
Eddington also helped verify the conclusions of the theory. Newton’s laws predicted that path of light from a star would be bent by the gravity of the sun by about 1.75 seconds of arc (the angle will vary depending on the exact situation). General Relativity also predicts bending, but the amount is exactly twice as large (by about 3.50 seconds of arc). Eddington thought that a solar eclipse would be the easiest way to measure the bending and verify the theory (normally glare from the sun makes this measurement impossible, during a solar eclipse the sun’s light is blocked and light from nearby stars can be seen and measured).
There would be an eclipse of the sun in 1919; at the time of the eclipse, the sun would be in the Hyades. If you take a photograph of the Hyades before the eclipse, and another during the eclipse, there should be a shift in the positions of the stars due to the Sun’s gravity. They planned an expedition to observe the eclipse, but World War I was still going on which made preparations difficult. Fortunately the war ended in late 1918, even so it was a difficult experiment. The eclipse path started in Brazil, passed over the South Atlantic and ended in West Africa. Making these measurements from a ship is almost impossible (and was not attempted), both Brazil and West Africa are frequently cloudy and there were problems with the telescopes.
In spite of the problems, the experiment was conducted and the results confirmed Einstein’s equations. It attracted a lot of public attention, perhaps because the public was tired of war, and eagerly wanted something else to talk about. There were headlines in the New York Times and other publications. Einstein soon become well known: There was a joke that only three people understood General Relativity (this was never true, but that doesn’t stop ideas like this from spreading). Someone asked Eddington about this. After the initial question, the exchange went something like this
Eddington: Oh Dear Me!
Questioner: Don’t be modest Eddington!
Eddington: I’m not being modest, I’m trying to think who the third person is.
Einstein was awarded the Nobel Prize in Physics in 1921. The Nobel committee specifically stated that the award was not for his work on relativity since it was “an unproven idea,” rather the award was given for his work on the photoelectric effect. Einstein was born in Germany but was a swiss citizen; he did part of his work in Switzerland and part in Germany. This created a diplomatic problem as both countries wanted to claim Einstein as a Nobel Laureate. Dr. Bell-Burnell did not know how this problem was resolved.
There have a number of applications of General Relativity. In 1979 radio astronomers discovered a pair of quasars with identical properties but 6 arc seconds apart. Before General Relativity, this was difficult to explain. However suppose there is just one quasar, and there is a galaxy located between the earth and the quasar.
In at the diagram above, the galaxy is marked G, the earth is marked E and the quasar is marked Q.
Light from the quasar is bent by the galaxy: it travels from Q to G’ to E and it travels Q to G” to E. An earth-bound observer would see what appears to be two identical quasars, one at Q’ and the other at Q”.
This bending can also create structures called Einstein Rings and called Einstein Crosses. This behavior is similar to what happens when a lens bends light, so the object in the middle is called the lensing object. The lensing object might be a star, a galaxy or even a cluster of galaxies. Typically light is bent by an angle of 1 second for a single galaxy, and 30 seconds for clusters of galaxies. By observing double quasars, rings or crosses, and assuming General Relativity is correct, it is possible to figure out how much mass the lensing object has.
We can estimate the total mass of a lensing object from the angle. If you estimate the mass of a galaxy and compare this to the observed velocities of stars within the galaxy, the velocities are too fast and the galaxy should fly apart. They do not; we now believe material called “dark matter” prevents this. By studying the lensing effect from galaxies and clusters of galaxies, we are able to determine the mass of these objects and in turn how much dark matter is present.
When a small object is directly between us and a galaxy, it can cause lensing. We call this microlensing.
In the diagram above, light from a galaxy (G) travels to the Earth (E). Nearby a dim star is moving from (S) to (S’). (The diagram is not to scale, the star is much closer to the Earth than the galaxy is). When the star is between the Earth and the galaxy, the light is bent slightly and the amount of bending changes as the star moves. By carefully measuring the light from many objects, we can detect the presence of stars or other objects too dim to observe in other ways. We’ve seen a lot of these events. In a few cases we see not just a hidden star, but something smaller as well. No one is certain, but the smaller objects just might be planets.
Another example is the orbit of Mercury. Mercury travels in an ellipse around the sun. However it isn’t a perfect ellipse, the other planets, particularly Jupiter, perturb the orbit and it precesses. In the late 1800’s astronomers worked out how much precession should be present, there was 43 arc seconds a year more precession than could be accounted for. Even though the effect was tiny, it bothered astronomers. The favored explanation was a hidden planet, which became known as Vulcan, resulted in extra precession. There isn’t room to explain the details here, but after General Relativity was described, it was realized that General Relativity predicts more precession than Newton’s equations do, exactly the amount to account for Mercury’s orbit. Vulcan was no longer necessary.
This precession effect is larger for binary pulsars, Dr. Bell-Burnell gave two examples, one with a precession of 4.2 degrees a year and the other with a precession of 17 degrees a year. In both cases the entire precession was due to General Relativity. While textbooks typically use Mercury’s orbit as an example, she suggested that pulsars might be a better example to use when teaching physics students.
Another example is gravitational waves. Einstein predicted that an object under acceleration will emit waves, which we now call gravitational waves. Unfortunately we’ve never observed these waves directly (there are some projects that may eventually detect these waves, but they are a few years off).
That doesn’t mean there is no evidence for gravitational waves. Suppose we have two stars in orbit. Accelerating objects, such as orbiting stars, emit gravitational waves. When a star emits a gravitational wave, it losses energy and thus losses mass. Kepler’s laws suggest that as stars lose mass, they must move toward each other and speed up. Then they emit more gravitational waves and speed up.
This has been observed. Some astronomers had monitored a binary pulsar for thirty years. The orbit was getting smaller and the velocities increasing in exactly way that General Relativity predicts it should.
That’s enough for now; I plan in a future article to discuss other aspects of gravity.
While most of the material for this article came Dr. Bell-Burnell’s talk, I also used the following book:
______. 1998. Einstein’s Miraculous Year: Five Papers That Changed the Face of Physics. John Stachel editor. Princeton University of Press: Princeton, New Jersey.
It contains new translations of all five papers I mentioned earlier. | <urn:uuid:327b8d0c-c173-4e54-8877-4b0756b9f89f> | 2.8125 | 2,951 | Personal Blog | Science & Tech. | 51.397609 |
European forestry scientists have begun a multi-national field trial to identify trees that will thrive as predicted climate change develops.
Thousands of trees are being planted in test plots from Portugal in the south to Scotland in the north. The trees will be measured and monitored as they grow in the diverse environments. The results are likely to have a marked impact on which species of trees are planted in the coming decades.
Scientists here - and across Europe - know that climate change is likely to have a big impact on how well trees survive and thrive in the future, and how resistant they may be to a new wave of disease which the predicted warmer conditions may bring.
Full Story: BBC
NB: Press Cutting Service
This article is culled from daily press coverage from around the world. It is posted on the Urban Gateway by way of keeping all users informed about matters of interest. The opinion expressed in this article is that of the author and in no way reflects the opinion of UN-HABITAT. | <urn:uuid:826ab840-c3ed-415f-a1c9-aa41d33005ce> | 3.234375 | 201 | Truncated | Science & Tech. | 46.723888 |
This section defines the term document, and provides additional details related to the definition of that term. It is divided into the following parts:
The term document is used in this reference to mean an instance of the HTML language.
The HTML language is the language described in this reference; it is an abstract language that applications can potentially represent in memory in any number of possible ways, and that can be transmitted using any number of possible concrete syntaxes.
This reference describes two particular concrete syntaxes for the HTML language: One syntax, which is referred to throughout this reference as the HTML syntax, and another syntax, which is referred to throughout this reference as the XML syntax. Web browsers typically implement two separate parsers for processing documents: an HTML parser which is invoked when processing documents in the HTML syntax, and an XML parser which is invoked when processing documents in the XML syntax.
The HTML syntax is the syntax described in the HTML syntax section of this reference.
The XML syntax is defined by rules in the [XML] specification and in the [Namespaces In XML] specification; any syntax-level requirements for documents in the XML syntax described in this reference are intended to be the same as those defined in the XML specification.
Documents that have an
declaration and that are served with an XML MIME type
match the descriptions in this
reference for characteristics of
documents in the XML syntax.
There are two types of conformant documents:
A conformant document in the HTML syntax must consist of the following parts, in the following order:
The start tag and end tag of the html element can be omitted—as well as, possibly, the start tags and end tags of certain descendants of the html element—in which case the start tag and end tag are considered to be implied.
Documents in the XML syntax must not make use of any features of the HTML syntax that do not follow XML well-formedness constraints (for example, documents in the XML syntax must not use unquoted attribute value syntax and must not omit tags). | <urn:uuid:eebf4fc3-50e8-4a30-8cd2-e866652b3b39> | 3.359375 | 417 | Documentation | Software Dev. | 29.187051 |
Liquid waste (urine) was collected in a Urine Collection Device, used in common by the crew of an Apollo spacecraft. Roll-on cuffs provided personal sanitary protection for the astronauts using the collection device. The urine was then transferred through the Urine Transfer Tube to a tank, from which the liquid waste was vented into space.
Fecal matter was sealed in a Fecal Bag with a liquid germicide and sealed again in an outer bag. This solid waste was then placed into a Sanitation Box built into the spacecraft.
Urine Transfer Tube
|©National Air and Space Museum| | <urn:uuid:89505a4d-c917-4239-81c3-171f5a456749> | 3.609375 | 126 | Knowledge Article | Science & Tech. | 36.259464 |
A 125-ft diameter, hemispherical bag of propane and oxygen, mixed in the ratio for maximum energy release. The striped poles support electronic pressure transducers. A human figure is seen against the bag in the lower right hand corner. This experiment also took place in Alberta, but in 1966, twenty-one years before the experiment pictured on our home page. We have been analyzing blast waves since 1958.
Next | Back | Quit | <urn:uuid:2c4cf84e-8c6b-4d5e-9a92-73243a56b7c2> | 2.859375 | 89 | Knowledge Article | Science & Tech. | 43.478338 |
We tend to think of glass as fragile--but in fact, glass is pretty strong stuff.
A discovery by students at Yale University might one day mean we can throw plastic into the compost pile.
Fish have been eating plastic in the Great Pacific Garbage Patch. This has scientists concerned about long term effects on the environment.
Ever wonder what actually happens when recycling plastics? Learn about the process on this Moment of Science.
Ever wonder how superglue works? Find out on this Moment of Science.
Inhaling insulin? Learn about different and painless way for diabetics to get their insulin on this Moment of Science.
The most important part of a seat belt is the spool’s locking mechanism–a device that makes the belt hold tight in the unfortunate event of a crash. The locking mechanism is activated either by the car’s movement or by the belt’s movement. | <urn:uuid:a26df4ce-2748-4918-aaf9-a7a333c7450e> | 2.875 | 187 | Content Listing | Science & Tech. | 61.8404 |
Fc-6 Attraction of two balls
Published: Monday 13 March 2006 - Updated: Tuesday 29 March 2011
To Demonstrate how pressure difference can cause attraction.
- Vacuum cleaner blower
- Apparatus as in diagram
Click on pictures to enlarge.
Attraction of Two Balls
The blower is aimed at the space between the two balls. The blower is connected to the variac and slowly brought up to full power. The pressure between th balls is reduced and they are subsequently " attracted". | <urn:uuid:04807275-c8c9-454a-9e41-2afe392d9437> | 2.71875 | 107 | Tutorial | Science & Tech. | 56.06374 |
Brief SummaryRead full entry
Green June Beetles (Cotinis nitida), common scarabaeid beetles in the subfamily Cetoniinae, are found in the southeastern and mid-Atlantic regions of the United States. Adults are 20 to 23 mm long. Larvae (grubs) feed on humus and roots in lawns and gardens and have the habit of crawling on their backs. Adults, which are active during the day, feed on foliage, flowers, and some fruit. Three other Cotinis species occur in the central and southern United States. (White 1983)
The Green June Beetle is of economic importance as a common pest of ripe or wounded tree and vineyard fruit. In the southeastern United States, where viticulture is an emerging industry, the proximity of pasture and other grassy larval habitats can lead to high numbers of these beetles in vineyards. Besides directly damaging the berries, Green June Beetles taint them with odorous secretions. Damaged fruits and the beetles themselves may be inadvertently harvested, contaminating the crop. Adult Green June Beetles normally feed on soft, ripe fruits, but the introduced Japanese Beetle (Popillia japonica)--first detected in North America in 1916 and now established throughout most of the eastern United States and continuing its spread into the Great Plains and south central states--facilitates access to foods on which the Green June Beetle could not otherwise feed. Whereas Green June Beetle mandibles are bluntly spatulate, non-opposable, and specialized for feeding on fruit pulp, plant exudates, and similar soft foods, Japanese Beetles have sharply pointed, opposable mandibles used mainly to skeletonize leaves, but also used to bite through intact skins of ripe fruits. Japanese Beetles facilitate feeding on grapes by Green June Beetles not only by biting through the skin and providing access to the pulp, but also by by eliciting yeast-mediated fermentation volatiles that Green June Beetles exploit in finding hosts.
(Hammons et al. 2008, 2009, 2010)
Pszczolkowski et al. (2008) discuss the limits of characters commonly used by researchers to distinguish male and female Green June Beetles.
Aktakka et al. (2011) used Green June Beetles to develop a prototype system for scavenging energy from a flying insect, with an eye toward using this energy in the fabrication of "hybrid insect vehicles", cyborg insects that could be controlled via neural, optical, or thermal stimulators, with the power for the inserted microsystem supplied by harvesting the insect’s available mechanical, thermal, or biological energy. The vision of investigators working on such "micro-air-vehicles" (MAVs), whether purely synthetic robots or cyborg insects, is that they could be used for search-and-rescue operations, surveillance, monitoring of hazardous environments, and detection of explosives by taking advantage of their small size and the networked communication possible between multiple MAVs. | <urn:uuid:d965ab50-b4e1-46a6-a33d-9e6cb75c7a96> | 3.734375 | 610 | Knowledge Article | Science & Tech. | 27.02268 |
Lectures for a New Year: A Physics Classic from 1960
In 1960, University of Toronto physics professors Patterson Hume and Donald Ivey produced a half-hour educational film explaining basic principles of physics. They called it Frames of Reference, and used the opportunity to make the seemingly-boring topic of physics education actually pretty fun (or at least as fun as an educational film from 1960 featuring dudes in suits could be). Using visual gags and a series of engaging experiments featuring themselves and hockey pucks, the professors explained how objects move, how we perceive their motion, and why those things matter. If you enjoy nothing else about this physics lecture, just check out their staging -- they had to build a complex set and camera rig to film this thing! This is one of several engaging films made by the seminal Physical Science Study Committee.
Topics: people upside-down, movement, velocity, observation, hockey pucks, force, unbalanced forces, and of course frames of reference.
For: anyone who wants to learn some basic physics, or who enjoys old educational films. There's also some inherent interest here for educators -- this film has been used in classrooms for fifty years to explain physics, and is a stellar example of how education on heady topics (like physics) doesn't have to be boring.
Viewing notes: Audio doesn't start until about 30 seconds in. Also, if the embedded video below doesn't work for you, try YouTube: part one, two, three. The YouTube videos are lower-quality, but work on more devices. A high-quality download is available from Archive.org.
Ivey and Hume also worked on the classic CBC TV series The Nature of Things. You can see more recent incarnations of the series from the CBC. The pair also wrote a book about physics (in two volumes) on the topic, though it's a little tricky to buy copies these days -- each volume goes for more than a hundred bucks on Amazon! Check for it in your local library instead (I found a library copy just ten miles away!).
I haven't been able to find a transcript of this talk. The only option I've found is to enable YouTube's automated captioning system, which frankly doesn't work very well with this fuzzy audio.
Suggest a Lecture
Got a favorite lecture? Is it online in some video format? Leave a comment and we'll check it out! | <urn:uuid:c4d0657d-5ed1-4aec-bb9f-7858512f620a> | 3.171875 | 492 | Truncated | Science & Tech. | 50.437549 |
Scotia Arc deep-water bivalves: composition, distribution and relationship to the Antarctic shelf fauna
Linse, Katrin. 2004 Scotia Arc deep-water bivalves: composition, distribution and relationship to the Antarctic shelf fauna. Deep-Sea Research Part II, 51 (14-16). 1827-1837. 10.1016/j.dsr2.2004.07.016Full text not available from this repository.
Agassiz trawl, epibenthic sledge and large box core samples were made in the Scotia and northern Weddell Seas during the 2002 ANDEEP expeditions with R.V. Polarstern at 21 locations (774-6348 in depth). The deep-water bivalve fauna sampled was species rich; in total 40 species of bivalves belonging to 17 families were found. At least seven of these species are new to science. Per location species richness varied from 5 to 15 species. Kelliella sirenkoi was the most common and abundant species, occurring at 17 locations (1121-6348 m), followed by Genaxius sp. 1 occurring at 12 locations. The epibenthic sledge hauls were characterised by low abundances, varying from 1 to 68 individuals 1000 m(-2) in depths greater than 1000 in. In comparison with the shelf fauna of the Scotia Arc, the deep-water bivalve community showed similar species richness. This indicates that there is no diversity cline with depth in Antarctic bivalves, but it does provide evidence for underestimated species richness in deep water because of lack of sampling.
|Programmes:||BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Antarctic Biodiversity - Past, Present and Future|
|NORA Subject Terms:||Marine Sciences
Biology and Microbiology
Ecology and Environment
|Date made live:||20 Jan 2012 11:29|
Actions (login required) | <urn:uuid:2f3a65ed-7d1c-4d5d-940c-292b12ee54e7> | 2.6875 | 410 | Academic Writing | Science & Tech. | 54.356529 |
Vegetation database of Great Britain: Countryside Survey
Maskell, Lindsay; Smart, Simon; Norton, Lisa; Wood, Claire. 2012 Vegetation database of Great Britain: Countryside Survey. Biodiversity & Ecology, 4. 383, pp. 10.7809/b-e.00172Full text not available from this repository.
This paper describes the vegetation database created as part of the Countryside Survey (CS) of Great Britain (GIVD ID EU-GB-003) which was established to monitor ecological and land use change in 1978 (http://www.countrysidesurvey.org.uk). The sample design is based on a series of stratified, randomly selected 1 km squares, which numbered 256 in the 1978 survey, 500 in the 1990 survey, 569 in the 1998 survey and 591 in the 2007 survey. Stratification of sample squares was based on predefined strata (called land classes) which have been derived from a classification of all 1 km squares in Britain based on their topographic, climatic and geological attributes obtained from published maps. A series of vegetation plots were located within each 1 km square using a restricted randomisation procedure designed to reduce aggregation. Linear features (road verges, watercourse banks, hedges, arable margins and field boundaries) and areal features (fields, unenclosed land and small semi-natural biotope patches) were sampled. Linear plots were 1 x 10 m laid out along a feature whilst unenclosed land and small biotopes were sampled using 2 m x 2 m plots. Larger randomly-placed plots were nested 14 m² plots with an inner nest of 2 m x 2 m. Within each 1 km Countryside Survey sample square the land cover and all landscape features were mapped and each parcel of land (and vegetation plot) has been assigned to a Broad Habitat/EUNIS habitat type. This database of vegetation plots is a very useful resource. The data is freely available from the website, however, there are restrictions on the release of the spatial location of the plots. There is now a considerable time-series of plots within the database going back to 1978 representing different habitat types and landscape features that can be analysed to determine changes in vegetation metrics (e.g. Ellenberg scores) and individual species. Vegetation changes can be linked to environmental drivers and the spatial scale (across GB) is sufficiently large to analyse gradients in most driving variables.
|Programmes:||CEH Topics & Objectives 2009 onwards > Biodiversity > BD Topic 1 - Observations, Patterns, and Predictions for Biodiversity > BD - 1.3 - Long-term/large-scale monitoring and experiments ...|
|Additional Information:||Open Access paper (short database report) - click on Official URL link for full text|
|NORA Subject Terms:||Ecology and Environment
Data and Information
|Date made live:||12 Oct 2012 15:08|
Actions (login required) | <urn:uuid:f83df053-7fd7-4ec5-ac1b-80c43a83eaf0> | 2.921875 | 618 | Academic Writing | Science & Tech. | 43.411818 |
Scientists with the Carnegie Institutions’s Department of Global Ecology at Stanford University and the University of Montana analyzed temperature, reflectivity, and evapotranspiration from satellite data across 733,000 square miles—an area larger than the state of Alaska. They found converting from natural cerrado grassland vegetation to crop/pasture on average triggered warming of 2.79 °F (1.55 °C), but that subsequent conversion to sugarcane, cooled the surrounding air by an average of 1.67 °F (0.93°C).
“We found that shifting from natural vegetation to crops or pasture results in local warming because the plants give off less beneficial water. But the bamboo-like sugarcane is more reflective and gives off more water—much like the natural vegetation,” said Carnegie’s Scott Loarie, lead author of the research. “It’s a potential win-win for the climate—using sugarcane to power vehicles reduces carbon emissions, while growing it lowers the local air temperature.”
- That Sound Is Churchill Turning In His Grave
- 1954-1955 : Five Major Hurricanes Struck The US In 14 Months
- Greenland Reaches A Tipping Point
- What If Grover Cleveland’s Hurricanes Happened Now?
- When Seconds Count, Police Are Just 20 Minutes Away
- Five Months After Sandy Hook – Not A Peep Out Of Obama About School Security
- Nobel Peace Prize Winner Has Been Killing American Citizens By Remote Control
- Quick Note To President Obama
- 1975 : Deep Dips In The Jet Stream Were Blamed On Global Cooling
- My Interest Is Ending Junk Science
- Piers Morgan Brags That Brits Don’t Have Guns And Can’t Defend Themselves
- Climate Science Is In The Crapper
- 1000 Km/Hr Winds From A Nuclear Bomb
- NOAA : Thirty Deadliest Tornado Years All Occurred Below 350 PPM
- Stunning CO2 Breakthrough : Age Of The US Controlled By Atmospheric CO2
- Bill Maher Vying To Replace Harold Camping
- Global Warming Shock News : New Mexico Is Just As Dry As 1904!
- UN Chief Says That The World Is Going To Run Out Of Water
- Obamacare Enforcement Chief Announces That Crimes Were Committed At The IRS
- A Tough Year For Climate Alarmists
- The New Normal : Ugly Junk Science
- Barbara Boxer Forecasts Summer Snow, Heat And Tornadoes
- Holder Wasn’t The Only Gun Runner In The White House
- Hasn’t Obama Overturned The Fifth Amendment Yet?
- 1927 Tornado Killed Scores Of People, Destroyed Thousands Of Homes In St. Louis
stevengoddard on That Sound Is Churchill Turnin… Bill S on That Sound Is Churchill Turnin… redc1c4 on When Seconds Count, Police Are… kbray in california on Greenland Reaches A Tipping… stevengoddard on 1975 : Tornado Outbreaks Blame… An Inquirer on 1975 : Tornado Outbreaks Blame… miked1947 on My Interest Is Ending Junk… miked1947 on My Interest Is Ending Junk… whatthedan on 1975 : Tornado Outbreaks Blame… miked1947 on 1000 Km/Hr Winds From A Nuclea… | <urn:uuid:805b7ae5-e1b9-4644-999f-2b679c68c0d5> | 3.171875 | 701 | Personal Blog | Science & Tech. | 31.999855 |
Mars Exploration Prizes
Google Tech Talk
June 10, 2010
Presented by Chris Carberry.
428 million years ago Pneumodesmus newmani, a Late Silurian millipede made a huge evolutionary leap. It is the first recorded creature to have left its natural habitat - the early ocean - and moved to live on land. Humanity lives in a similar period today, we have just started leaving our natural habitat - the Earth. And we will soon travel and even colonize Mars.
Mars prizes have been discussed for years, but this concept has never gained momentum because the majority of Mars Prize proposals have required investments of several billions of dollars with the singular goal of landing humans on the surface of Mars. While humans to Mars is our eventual goal as well, a Mars prize does not need cost billions of dollars. In actuality, important Mars related innovation can be achieved with prizes levels as small as $10,000-$100,000. In this talk, Explore Mars Executive Director, Chris Carberry, will discuss a series of Mars Exploration Challenges that Explore Mars, Inc. will launch starting in 2010. The first of these challenges will be the In Situ Resource Utilization (ISRU) Challenge. With this prize, Explore Mars, Inc. will be challenging teams around the country to develop technology and innovations that will help future astronauts to be able to "live off the land" on the Martian surface. This type of challenge can be a potent force in innovating technology necessary for sending humans to Mars. Of equal importance, this type of prize can also influence space policy. While Mars has been mentioned as the ultimate destination of the United States space program, real private sector contributions to technology development can have a real impact on space policy. Technology development prizes can also create stability. ISRU was part of the NASA exploration budget several years ago, but it fell victim to budget cuts before the program was able to fulfill its purpose. Mars prizes can provide momentum and stability that is necessary to continuously advance vital technologies.
Over the next few years, Explore Mars will launch several prizes with the goal of advancing the engineering, science, medicine, education, and overall study of Mars. In addition to discussing these prize concept, Chris will also want to brainstorm with the Google audience to discuss technical and societal issues that will need to be overcome to if humanity is ever going to be able to set foot on Mars.
This talk was hosted by Boris Debic.
Chris Carberry Chris Carberry is the Executive Director and co-founder of Explore Mars, Inc.. Prior to Explore Mars, Chris served as Executive Director of The Mars Society. In addition, Chris has served as Chairman of The Mars Societty Steering Committee and was Political Director for that organization. Chris served as chairman or co-coordinator of such congressional lobbying events as the 2007-2010 Space Budget Blitz, the 2007 Moon-Mars Blitz, the 2006 Space Blitz, and the Great 2006 Mars Blitz. Chris also serves as the Chairman of the Steering Committee of the Space Exploration Alliance, which is an umbrella group representing 13 space advocacy organizations with total membership of over 700,000 people. He also served on the Board of Directors for the National Space Society. Chris is the author of many articles and Op-Ed pieces concerning space policy and politics. In addtion, Chris is the author of a mystery/science fiction novel called Celestial Pursuits: in the hub of the Universe which was published in 2006. In 2007, Chris signed a movie option contract for Celestial Pursuits, with a Los Angeles production company. Chris also has an extensive background in historical research, having worked as research assistant for several authors, including British biographer Sarah Bradford (America's Queen) and former New York Times Magazine editor Ed Klein (The Kennedy Curse). | <urn:uuid:1721bf4d-35bc-4c3a-80c9-de3fdb834f39> | 2.703125 | 769 | Truncated | Science & Tech. | 38.369641 |
On the BTE site I talk about using lasers to dig underground cavities on Mars for establishing a permanent base there. One advantage of bases deep underground is that they provide for complete shielding from galactic cosmic rays and radiation from the sun. A second advantage is that the inside surfaces of the cavities that are cut out within solid rock can serve as the walls, ceilings, and floors for rooms in the base. This minimizes the size and mass of structures that must be sent to Mars for constructing bases.
Using lasers to cut through rock is a technology that is almost completely unknown to most people, including people with technical educations or training. (You heard about it on the BTE site first!) There have been exactly zero videos on YouTube about using lasers to cut through rock. So today I copied two videos from the Argonne National Laboratory website on to YouTube. The videos are below.
The first video is just 37 seconds long. It shows a laser drilling a hole through a rock. The nice thing about this method of drilling is that it simply vaporizes the rock, and this eliminates debris while drilling. Think about creating underground bases on Mars for a moment inside of solid rock. Are we going to try to dynamite it room by room and then send bulldozers up to Mars to clean up all the debris? I don’t think so. So the great promise of using “laser-diggers”, as I called them on the BTE site, is that this would eliminate all of this old-fashioned messiness.
So imagine say five wheeled vehicles on Mars, each with a powerful laser mounted on it, as this group of laser-diggers works together drilling. Each laser would have a few thousand times greater output power than the one shown in the video. This would be pretty awesome to watch. And it seems rather Star Trekish, which makes it even more fun.
The second video is an extended piece from the History Channel about the coming of laser drilling technology to drill through rock. | <urn:uuid:99b697a9-245b-4ea6-b3b3-e212255f81d6> | 3.40625 | 412 | Personal Blog | Science & Tech. | 55.618718 |
The following shell builtin commands are inherited from the Bourne Shell. These commands are implemented as specified by the POSIX standard.
: (a colon)
Do nothing beyond expanding arguments and performing redirections. The return status is zero.
. (a period)
. filename [arguments]
Read and execute commands from the filename argument in the
current shell context. If filename does not contain a slash,
PATH variable is used to find filename.
When Bash is not in POSIX mode, the current directory is searched
if filename is not found in
If any arguments are supplied, they become the positional
parameters when filename is executed. Otherwise the positional
parameters are unchanged.
The return status is the exit status of the last command executed, or
zero if no commands are executed. If filename is not found, or
cannot be read, the return status is non-zero.
This builtin is equivalent to
Exit from a
If n is supplied, the nth enclosing loop is exited.
n must be greater than or equal to 1.
The return status is zero unless n is not greater than or equal to 1.
cd [-L|[-P [-e]]] [directory]
Change the current working directory to directory.
If directory is not given, the value of the
variable is used.
If the shell variable
CDPATH exists, it is used as a search path.
If directory begins with a slash,
CDPATH is not used.
The -P option means to not follow symbolic links; symbolic
links are followed by default or with the -L option.
If the -e option is supplied with -P
and the current working directory cannot be successfully determined
after a successful directory change,
cd will return an unsuccessful
If directory is ‘-’, it is equivalent to
If a non-empty directory name from
CDPATH is used, or if
‘-’ is the first argument, and the directory change is
successful, the absolute pathname of the new working directory is
written to the standard output.
The return status is zero if the directory is successfully changed, non-zero otherwise.
Resume the next iteration of an enclosing
If n is supplied, the execution of the nth enclosing loop
n must be greater than or equal to 1.
The return status is zero unless n is not greater than or equal to 1.
The arguments are concatenated together into a single command, which is
then read and executed, and its exit status returned as the exit status
If there are no arguments or only empty arguments, the return status is
exec [-cl] [-a name] [command [arguments]]
is supplied, it replaces the shell without creating a new process.
If the -l option is supplied, the shell places a dash at the
beginning of the zeroth argument passed to command.
This is what the
login program does.
The -c option causes command to be executed with an empty
If -a is supplied, the shell passes name as the zeroth
argument to command.
If no command is specified, redirections may be used to affect
the current shell environment. If there are no redirection errors, the
return status is zero; otherwise the return status is non-zero.
Exit the shell, returning a status of n to the shell’s parent.
If n is omitted, the exit status is that of the last command executed.
Any trap on
EXIT is executed before the shell terminates.
export [-fn] [-p] [name[=value]]
Mark each name to be passed to child processes in the environment. If the -f option is supplied, the names refer to shell functions; otherwise the names refer to shell variables. The -n option means to no longer mark each name for export. If no names are supplied, or if the -p option is given, a list of exported names is displayed. The -p option displays output in a form that may be reused as input. If a variable name is followed by =value, the value of the variable is set to value.
The return status is zero unless an invalid option is supplied, one of the names is not a valid shell variable name, or -f is supplied with a name that is not a shell function.
getopts optstring name [args]
getopts is used by shell scripts to parse positional parameters.
optstring contains the option characters to be recognized; if a
character is followed by a colon, the option is expected to have an
argument, which should be separated from it by white space.
The colon (‘:’) and question mark (‘?’) may not be
used as option characters.
Each time it is invoked,
places the next option in the shell variable name, initializing
name if it does not exist,
and the index of the next argument to be processed into the
OPTIND is initialized to 1 each time the shell or a shell script
When an option requires an argument,
getopts places that argument into the variable
The shell does not reset
OPTIND automatically; it must be manually
reset between multiple calls to
getopts within the same shell
invocation if a new set of parameters is to be used.
When the end of options is encountered,
getopts exits with a
return value greater than zero.
OPTIND is set to the index of the first non-option argument,
and name is set to ‘?’.
normally parses the positional parameters, but if more arguments are
given in args,
getopts parses those instead.
getopts can report errors in two ways. If the first character of
optstring is a colon, silent
error reporting is used. In normal operation diagnostic messages
are printed when invalid options or missing option arguments are
If the variable
is set to 0, no error messages will be displayed, even if the first
optstring is not a colon.
If an invalid option is seen,
getopts places ‘?’ into name and, if not silent,
prints an error message and unsets
getopts is silent, the option character found is placed in
OPTARG and no diagnostic message is printed.
If a required argument is not found, and
is not silent, a question mark (‘?’) is placed in name,
OPTARG is unset, and a diagnostic message is printed.
getopts is silent, then a colon (‘:’) is placed in
OPTARG is set to the option character found.
hash [-r] [-p filename] [-dt] [name]
hash is invoked, it remembers the full pathnames of the
commands specified as name arguments,
so they need not be searched for on subsequent invocations.
The commands are found by searching through the directories listed in
Any previously-remembered pathname is discarded.
The -p option inhibits the path search, and filename is
used as the location of name.
The -r option causes the shell to forget all remembered locations.
The -d option causes the shell to forget the remembered location
of each name.
If the -t option is supplied, the full pathname to which each
name corresponds is printed. If multiple name arguments are
supplied with -t the name is printed before the hashed
The -l option causes output to be displayed in a format
that may be reused as input.
If no arguments are given, or if only -l is supplied,
information about remembered commands is printed.
The return status is zero unless a name is not found or an invalid
option is supplied.
Print the absolute pathname of the current working directory. If the -P option is supplied, the pathname printed will not contain symbolic links. If the -L option is supplied, the pathname printed may contain symbolic links. The return status is zero unless an error is encountered while determining the name of the current directory or an invalid option is supplied.
readonly [-aAf] [-p] [name[=value]] …
Mark each name as readonly. The values of these names may not be changed by subsequent assignment. If the -f option is supplied, each name refers to a shell function. The -a option means each name refers to an indexed array variable; the -A option means each name refers to an associative array variable. If both options are supplied, -A takes precedence. If no name arguments are given, or if the -p option is supplied, a list of all readonly names is printed. The other options may be used to restrict the output to a subset of the set of readonly names. The -p option causes output to be displayed in a format that may be reused as input. If a variable name is followed by =value, the value of the variable is set to value. The return status is zero unless an invalid option is supplied, one of the name arguments is not a valid shell variable or function name, or the -f option is supplied with a name that is not a shell function.
Cause a shell function to exit with the return value n.
If n is not supplied, the return value is the exit status of the
last command executed in the function.
This may also be used to terminate execution of a script being executed
source) builtin, returning either n or
the exit status of the last command executed within the script as the exit
status of the script.
Any command associated with the
RETURN trap is executed
before execution resumes after the function or script.
The return status is non-zero if
return is used outside a function
and not during the execution of a script by
Shift the positional parameters to the left by n.
The positional parameters from n+1 …
Parameters represented by the numbers
n must be a non-negative number less than or equal to
If n is zero or greater than
$#, the positional parameters
are not changed.
If n is not supplied, it is assumed to be 1.
The return status is zero unless n is greater than
less than zero, non-zero otherwise.
Evaluate a conditional expression expr.
Each operator and operand must be a separate argument.
Expressions are composed of the primaries described below in
Bash Conditional Expressions.
test does not accept any options, nor does it accept and ignore
an argument of -- as signifying the end of options.
[ form is used, the last argument to the command must
Expressions may be combined using the following operators, listed in decreasing order of precedence. The evaluation depends on the number of arguments; see below. Operator precedence is used when there are five or more arguments.
True if expr is false.
( expr )
Returns the value of expr. This may be used to override the normal precedence of operators.
expr1 -a expr2
True if both expr1 and expr2 are true.
expr1 -o expr2
True if either expr1 or expr2 is true.
[ builtins evaluate conditional
expressions using a set of rules based on the number of arguments.
The expression is false.
The expression is true if and only if the argument is not null.
If the first argument is ‘!’, the expression is true if and only if the second argument is null. If the first argument is one of the unary conditional operators (see Bash Conditional Expressions), the expression is true if the unary test is true. If the first argument is not a valid unary operator, the expression is false.
The following conditions are applied in the order listed. If the second argument is one of the binary conditional operators (see Bash Conditional Expressions), the result of the expression is the result of the binary test using the first and third arguments as operands. The ‘-a’ and ‘-o’ operators are considered binary operators when there are three arguments. If the first argument is ‘!’, the value is the negation of the two-argument test using the second and third arguments. If the first argument is exactly ‘(’ and the third argument is exactly ‘)’, the result is the one-argument test of the second argument. Otherwise, the expression is false.
If the first argument is ‘!’, the result is the negation of the three-argument expression composed of the remaining arguments. Otherwise, the expression is parsed and evaluated according to precedence using the rules listed above.
The expression is parsed and evaluated according to precedence using the rules listed above.
When used with
test or ‘[’, the ‘<’ and ‘>’
operators sort lexicographically using ASCII ordering.
Print out the user and system times used by the shell and its children. The return status is zero.
trap [-lp] [arg] [sigspec …]
The commands in arg are to be read and executed when the
shell receives signal sigspec. If arg is absent (and
there is a single sigspec) or
equal to ‘-’, each specified signal’s disposition is reset
to the value it had when the shell was started.
If arg is the null string, then the signal specified by
each sigspec is ignored by the shell and commands it invokes.
If arg is not present and -p has been supplied,
the shell displays the trap commands associated with each sigspec.
If no arguments are supplied, or
only -p is given,
trap prints the list of commands
associated with each signal number in a form that may be reused as
The -l option causes the shell to print a list of signal names
and their corresponding numbers.
Each sigspec is either a signal name or a signal number.
Signal names are case insensitive and the
SIG prefix is optional.
If a sigspec
EXIT, arg is executed when the shell exits.
If a sigspec is
DEBUG, the command arg is executed
before every simple command,
select command, every arithmetic
for command, and before
the first command executes in a shell function.
Refer to the description of the
extdebug option to the
shopt builtin (see The Shopt Builtin) for details of its
effect on the
If a sigspec is
RETURN, the command arg is executed
each time a shell function or a script executed with the
source builtins finishes executing.
If a sigspec is
ERR, the command arg
is executed whenever a simple command has a non-zero exit status,
subject to the following conditions.
ERR trap is not executed if the failed command is part of the
command list immediately following an
part of the test following the
elif reserved words,
part of a command executed in a
or if the command’s return
status is being inverted using
These are the same conditions obeyed by the
Signals ignored upon entry to the shell cannot be trapped or reset. Trapped signals that are not being ignored are reset to their original values in a subshell or subshell environment when one is created.
The return status is zero unless a sigspec does not specify a valid signal.
umask [-p] [-S] [mode]
Set the shell process’s file creation mask to mode. If
mode begins with a digit, it is interpreted as an octal number;
if not, it is interpreted as a symbolic mode mask similar
to that accepted by the
chmod command. If mode is
omitted, the current value of the mask is printed. If the -S
option is supplied without a mode argument, the mask is printed
in a symbolic format.
If the -p option is supplied, and mode
is omitted, the output is in a form that may be reused as input.
The return status is zero if the mode is successfully changed or if
no mode argument is supplied, and non-zero otherwise.
Note that when the mode is interpreted as an octal number, each number
of the umask is subtracted from
7. Thus, a umask of
results in permissions of
unset [-fv] [name]
Each variable or function name is removed. If no options are supplied, or the -v option is given, each name refers to a shell variable. If the -f option is given, the names refer to shell functions, and the function definition is removed. Readonly variables and functions may not be unset. The return status is zero unless a name is readonly. | <urn:uuid:e5d9d2b5-d096-4434-8dd6-72abf8fe63b3> | 3.171875 | 3,553 | Documentation | Software Dev. | 50.687942 |
Comets are best described as "dirty snowballs". They are about five
miles in diameter and travel around the Sun in highly elongated orbits.
As they approach the Sun, its heat causes some of the comet's icy material
to evaporate and then the solar wind pushes these loosened particles
away, creating the long, beautiful tails.
believed initially that the dark regions, where little to no stars
were seen, are "holes" or voids in
the distribution of stars in the Galaxy. It is now realized that these "holes" are
due to dark nebulae that obscure the light from the more distance
stars behind them.
Lanes are regions of dark nebula
superimposed on a starry background that appear to be long, finger–like
A nebula (pl. nebulae) is a diffuse "cloud" of interstellar gas and
dust. There are a variety of types, including dark, obscuring nebulae
and hot, bright emission nebulae. These nebulae are several light years
across and contain hundreds of times the mass of the Sun; however,
the density is rather low.
terms indicated the apparent distance of the starry background. Usually
there are gas and dust clouds in front of the starry background, and
the obscured regions appear as dark regions or lanes.
use a coordinate system for the positions of celestial objects that
is very similar to the Earth's system of latitude and longitude. Declination is
directly correlated to latitude. The range is from +90o (North
Celestial Pole) to 0o (Celestial
Equator) to –90o (Celestial South
Due to the Moon's gravitational
pull, the Earth slowly wobbles. This causes the Right Ascension and
Declination values to shift. Consequently, an "Epoch" is given with
the coordinates to indicate the date for when these values were exactly
Astronomers measure distances
to nearby stars by the same triangulation technique that surveyors use.
The Parallax of a star is the angular change (in arcseconds) produced
by the orbit of the Earth. The distance in parsecs is equal to the reciprocal
of the parallax angle. Example: If the parallax is 0.05 arcsec, the distance
1 / 0.05 = 20 parsecs.
Astronomers use a coordinate system for the positions of celestial objects that
is very similar to the Earth's system of latitude and longitude. Right Ascension is
similar to longitude except that the parameter range is from 0 to 24 hours instead
of 0 to 360 degrees.
Bayer in the early 1600s (usually) ranked stars in a given constellation
by brightness. The brightest was designated as ,
followed by the constellation name. Subsequent designations would be ,,,
etc. Examples include Ori
John Flamsteed produced
an Atlas containing 54 constellations in the 1700s. The stars were given
consecutive numbers in order of their right ascension.
Most stars are too
faint to have proper names, so they are identified by a specific number
in various star catalogs, such as the Bonner Durchmusterung (BD) or
the Cape Photographic Durchmusterung (CPD). These particular catalogs
number the stars in order of right ascension per declination zone.
Example: the first star (near RA 0 h00m 00s )
in the declination zone from 22o to 23o is BD
Charles Messier was a
comet hunter in the late 1700s who became tired of finding the same nebulous–appearing
objects in the sky. He made a list of 103 such objects. A few examples
include the Andromeda Galaxy (M31) and the Orion Nebula (M42).
Telescopes are described by their aperture (i.e., diameter), for this
characteristic is an indicator of how much light it can gather. The
larger the aperture, the larger the collecting area and therefore
the "deeper" or "fainter" it can see.
This optical system of two lenses has a wide aperture and is free from optical
There are two types of optical
telescopes. Refractors use a large lens at the front of the telescope
tube that focuses the light to an eyepiece at the back of the tube.
There are two types of optical
telescopes. Reflectors use a curved mirror at the back of the tube that
focuses the light to a mirror at the front of the tube, which in turn
reflects the light to an eyepiece.
Verniers are small scales of tick marks attached next to the coordinate
wheels on a telescope. They are used to improve the precision of "reading" the
coordinates to which the telescope is pointed.
These are the mechanical gears
that turn the telescope so that it tracks objects on the sky. Because
the Earth is rotating, the sky appears to spin around us. If a telescope
did not track, then the objects could only be viewed for a short time
before they moved out of the telescope's field of view. | <urn:uuid:a7b4b35b-2a42-44ce-bc41-129f88fc233f> | 4.15625 | 1,099 | Structured Data | Science & Tech. | 47.819284 |
System.out.print\n("Number Squared Cubed"); // this line was the
hint we were given
maybe changed print\n to println ?
Frank Murphy (Frankly3D) wrote:
> Google no help, with my brain anyhow.
>http://tinyurl.com/yez6rnr>> Numbers 1 to 10, original squared and cubed, displayed like a table.
>> This cause an error, as it stands:
> illegal character:\92
>> It's the "\"
>> public class table
> public static void main(String args)
> int Number = 0;
>> int Squared = 0;
> Squared = (Number*Number);
>> int Cubed = 0;
> Cubed = (Squared*Number);
>> for (Number = 1; Number <= 10; Number = Number+1)
> System.out.print\n("Number Squared Cubed"); // this line was
> the hint we were given
Stephen Mulcahy Atlantic Linux http://www.atlanticlinux.ie
Registered in Ireland, no. 376591 (144 Ros Caoin, Roscam, Galway)
Maintained by the ILUG website team. The aim of Linux.ie is to
support and help commercial and private users of Linux in Ireland. You can
display ILUG news in your own webpages, read backend
information to find out how. Networking services kindly provided by HEAnet, server kindly donated by
Dell. Linux is a trademark of Linus Torvalds,
used with permission. No penguins were harmed in the production or maintenance
of this highly praised website. Looking for the
Indian Linux Users' Group? Try here. If you've read all this and aren't a lawyer: you should be! | <urn:uuid:3c126be6-4fff-4a32-b426-843983b5ee1e> | 2.875 | 390 | Comment Section | Software Dev. | 67.975298 |
The Blueness of the Sky
Molecules of certain atmospheric gasses scatter some sunlight. The scattering process involves preferentially the short wavelengths of light, as are the molecules. Therefore, the light scattered by the atmosphere, the sky light, is blue. When the scattering particles are not small in comparison with the wavelengths, such as dust particles in the air, including condensation nuclei, the scattering involves more of the longer wavelengths. Because there is always some dust in the air, the sky light also contains longer wavelengths such as green and red, although the color mixture still looks blue. The more numerous and larger the dust particles are, the more of the other colors are mixed with the blue, and the paler the blue becomes. For this reason, the sky is rarely seen as deeply blue in industrial areas as in rural ones. Also in humid air masses, in which condensation nuclei take on water vapor from the air, the sky is paler blue than in dry air masses.
You can imitate the process that causes the blueness of the sky by letting extremely small particles scatter sunlight or light from a very bright source (projector), looking at the scattering particles from a direction perpendicular to the light beam. Minute particles are contained in certain suspensions, such as soap in water (if the water is not too hard), milk in water, a weak silver nitrate solution, or "hypo" (photographic fixer).
Fill a glass container, such as a small fish bowl or bottle with smooth sides and rectangular horizontal cross section, with water and place a sheet of black paper behind it. Let a strong light beam fall on the container from the right or the left side. Put a few drops of milk into the water with an eye dropper, stir, and observe. Add more milk, stir, and observe the changes that take place. When the mixture shows a distinctly bluish color, look through it directly at the light source.
Repeat the experiment using a soap solution, made from a few soap shavings dissolved in a little hot water. Compare the results with the previous ones.
If you can get some from a photographic store. use hypo and silver nitrate, which shows the effect particularly well. If no ready-make hypo is available, we make a strong solution of sodium-thiosulfate in water and add a little vinegar.
Repeat the experiment with a corn-starch solution. There should be a difference in clolor between the starch and the other materials as the particles are larger.
Material: Glass container, preferably of rectangular cross section with smooth sides
Some milk, soap, silver nitrate, photographic fixing solution, corn starch
Water, black pepper | <urn:uuid:60acd132-d40c-4d25-9829-ac5922acc015> | 3.734375 | 553 | Tutorial | Science & Tech. | 46.158354 |
Find out how hurricanes can be so destructive
Submitted by Jur on Tue, 10/30/2012 - 21:48
Hurricanes batter coastlines and send deadly debris flying through the air.
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In the 1978 film ‘The Boys from Brazil’, Nazi scientists produce clones of Adolf Hitler: babies genetically identical to the dead dictator.
The film is science fiction, but some people felt the announcement of Dolly's birth in February 1997 moved the eerie scenario closer to reality.
How scientists made Dolly, first clone of an adult mammal (Discovery)
For thousands of years, people have been growing new plants by taking cuttings.
The new plant is genetically identical to the existing one.
Dolly was the animal equivalent of a cutting – although the procedure was vastly more complicated.
She was born, after a normal pregnancy, at the Roslin Institute, Edinburgh, on July 5th 1996.
The embryo from which Dolly developed was made in an unusual way. Most cells of an adult animal contain a complete set of chromosomes in the nucleus.
A human cell contains 46 in 23 pairs.
Eggs and sperm cells are different: they contain only one member of each pair.
When a human sperm enters an egg, it adds its 23 unpaired chromosomes to the 23 in the egg, making a new, unique combination with a full complement of 46.
Dolly was created using a different procedure called nuclear transfer.
First, the scientists removed the nucleus from a ewe’s egg – so that it contained no chromosomes at all.
Then they took a nucleus from a cell taken from an adult sheep – with a complete set of chromosomes – and inserted it into the ‘empty’ egg.
The egg then behaved as if it had been fertilised. It began to divide, forming an embryo, which the researchers implanted into a ewe.
Five months later Dolly was born. She was genetically identical to the sheep from which the cell was taken: an identical twin separated by a generation.
Dolly was created as part of research into genetic engineering, in which genes from one organism can be inserted into the chromosomes of another.
This could result in a sheep that produces milk containing useful medical drugs, for example.
Once the ‘perfect’ animal had been engineered, it could be cloned indefinitely.
Biologists cloned frogs in the 1950s. Mice were cloned in the 1980s, although only by dividing embryos and implanting the two halves separately.
Dolly was the first clone from an adult mammal cell. Her birth made headline news around the world.
It raised moral questions, largely because Dolly was a mammal: if a sheep can be cloned, why not a human being?
There is little justification for trying reproductive cloning in humans – for now, the risks remain too high.
Nevertheless, there are those determined to go ahead, and the first human clone will probably be born this century.
One type of human cloning is being pursued by mainstream researchers: therapeutic cloning.
This involves taking cells from a cloned embryo; it does not result in a new person.
Part of an embryo is made of ‘stem cells’, which can develop into any kind of tissue.
In the laboratory, embryonic stem cells can be nurtured to make living tissue – which could cause a revolution in medicine, treating conditions from burns to Parkinson’s disease.
In the future, scientists may be able to grow whole organs.
The fact that the embryos are cloned from the patient means the laboratory-grown tissues and organs could be transplanted without rejection.
lightbox mind boggler | <urn:uuid:919bb720-fe73-4c4d-8e80-d36222d27f98> | 3.453125 | 717 | Nonfiction Writing | Science & Tech. | 49.41905 |
Planetary Triangle Forming in the Evening Sky Jul 29, 2010 22:06:33 GMT 1
Post by uforn on Jul 29, 2010 22:06:33 GMT 1
Planetary Triangle Forming in the Evening Sky
By Geoff Gaherty
Starry Night Education
posted: 28 July 2010
10:00 am ET
On the evening of Aug. 5, Venus, Mars and Saturn will
gather in the western sky bracketed by the stars Zaniah
and Zavijava in Virgo. All three planets will fit in a 10x50
binocular field, as shown by the circle. Credit: Starry Night
A trio of planets converging in the night sky this week and for several nights will give casual skywatchers the perfect chance to easily see and identify worlds they might not normally notice. The event, building up to a super celestial snuggle in early August, is also a chance to watch and grasp orbital mechanics in action.
Venus, Mars and Saturn will gradually, night after night, move into a tight triangular grouping in the early evening sky. (This graphic shows where to look to spot the planetary triangle on Aug. 5.)
Venus is so bright, you can't miss it, and that will allow you to locate the other two worlds with no trouble. You can start watching the spectacle tonight. [Venus photos from around the world.]
The ancients believed planetary alignments to be full of mystery portending dreadful events. Now we realize that, because the planets all move in a common plane called the ecliptic, they regularly line up with each other over time as seen from planet Earth.
The ecliptic is the same path across the sky followed by the sun, and so the three planets will appear to be following the sun into the Western horizon as darkness falls.
The ecliptic corresponds to the plane in space that Earth and the other planets travel in as the orbit the sun. Since the inner planets, like Venus, make their annual orbits faster than the outer worlds, like Mars, they're constantly trading places in our sky, converging and receding from one another as seen from our vantage point.
Planetary alignments are known to astronomers as conjunctions or appulses. The moon, which is also traveling close to the plane the planets orbit in, is in conjunction with each of the planets at some point every month. Conjunctions between pairs of planets, particularly the faster moving inner planets, occur several times a year.
Conjunctions of three or more planets are much rarer. This one has been building for several months, and will reach its culmination in the coming week.
What you'll see
Look in the western sky just after sunset any night this week. Your eyes will immediately be drawn to the brilliant planet Venus – it's brighter than any night sky object except the moon.
Look more closely as the sky gets darker, and you will see that Venus is accompanied by two lesser lights. These are the planets Mars and Saturn.
On Saturday night, July 31, Mars will be just below Saturn, less than two degrees away (your fist on an outstretched arm measures about 10 degrees of the sky). The following Saturday, Aug. 7, Venus will have moved westward so that it is less than three degrees below Saturn.
All three planets are moving eastward (left to right for viewers in the Northern Hemisphere) against the background stars of the constellation Virgo. The solar system's inner planets move across our sky (and around the sun) in much less time much than the outer planets, and so they rapidly move past distant Saturn.
On Thursday night, Aug. 5, the three planets will be closest together, forming a tight triangle that will easily fit in the field of binoculars.
Appearances are deceptive. Although close together in the sky, the three planets are actually at very different distances from the Earth.
Venus is closest at 0.796 astronomical units distance, Mars next at 2.022 astronomical units, and Saturn a distant 10.191 astronomical units. Because distances to other planets are, well, astronomical if measured in miles or kilometers, astronomers usually measure them in astronomical units: an astronomical unit is the average distance between the Earth and the Sun, 93 million miles or 150 million kilometers.
Gallery - Venus Seen From Around the World
Amazing Photos of Mars
Telescopes for Beginners
This article was provided to SPACE.com by Starry Night Education, the leader in space science curriculum solutions.
Original Story: Check It Out: Planetary Triangle Forming in the Evening Sky | <urn:uuid:22a96a8e-d9a6-472e-bda6-2186d8e419a9> | 3.1875 | 950 | Comment Section | Science & Tech. | 55.0582 |
|M1750 Ada Technical Summary: For mission-critical applications|
|Prev||Chapter 6. Cross-Compiler and Run-Time Interfacing||Next|
Technically, the crucial asset of the GCC is its mostly language-independent, target-independent code generator. It produces code of excellent quality both for CISC machines such as the Intel and Motorola families, as well as RISC machines such as the IBM RS/6000. The machine dependencies of the code generator represent less than 10 per cent of the total code.
To add a new target to GCC, an algebraic description of each machine instruction must be given using a register-transfer language. Most of the code generation and optimization then uses the RTL, which GCC maps when needed into the target machine language. Furthermore, GCC produces high-quality code, comparable to that of the best compilers. | <urn:uuid:e477ecbc-bcc1-47ac-8deb-c69d81d0cb01> | 2.765625 | 177 | Documentation | Software Dev. | 38.74 |
When Rachel Carson wrote her famous book Silent Spring, she envisioned a world in which chemical pollutants killed off wildlife, to the extent that singing birds could no longer be heard. Pesticides aside, we now know that humans have challenged birds with another type of pollution, which also threatens to silence their beautiful songs – noise.
A man-made world is a loud one. Between the din of cities and the commotion of traffic, we flood our surroundings with a chronic barrage of sound. This is bad news for songbirds. We know that human noise is a problem for them because some species go to great lengths to make themselves heard, from changing their pitch (great tits) to singing at odd hours (robins) to just belting their notes out (nightingales). We also know that some birds produce fewer chicks in areas affected by traffic noise.
Now, Julia Schroeder from the University of Sheffield has found one reason for this. She has shown that loud noises mask the communication between house sparrow mothers and their chicks, including the calls that the youngsters use to beg for food. Surrounded by sound, the chicks eat poorly. “City noise has the potential to turn sparrow females into bad mothers,” says Schroeder.
Her work is important because it shows how exactly man-made noise could affect birds. Only a handful of other studies have done this. We know that house finches spend so much effort on making themselves heard that their songs are shorter, and thus less sexy. Zebra finches fail to hear their partners’ calls, eroding the bonds between otherwise monogamous mates. There are other possibilities: noise could stop birds from proclaiming their territories or warning of danger.
Schroeder cut through the competing hypotheses by studying a unique group of sparrows living in Lundy Island, a small body of land in the Bristol Channel, England. Sparrows are short-distance fliers so the Lundy population is fairly self-contained, and scientists have been studying them for 12 years. They know every individual, and have tracked them through their entire lifespan. Eggs are regularly swapped between nest boxes, so parent birds become unknowing surrogates for unrelated chicks. These “cross-fostering” experiments allow scientists to tease apart the influence of the sparrow’s environment from that of their parentage.
In March 2001, a set of electrical generators were switched on in the island. They run continuously from 6 am to 9 pm, and produce 70 decibels of noise – about as much as a rowdy primary school classroom. You have to speak up to be heard.
Schroeder compared a set of sparrow nest boxes within this zone of noise to those at three distant quiet zones. The noise wasn’t obviously harming the parent birds. It didn’t affect how many eggs the females laid, how intently they attended to their clutch, or how much they weighed. And the nestboxes near the generators attracted birds or all ages and from all walks of sparrow life, so it wasn’t the case that the fittest birds took up the quiet real estate and left the noisy dregs for the weaker ones.
For the chicks, it was a different story. They had a 25 per cent chance of living long enough to fledge if they lives in a quiet environment, but just a 21 per cent chance if they lived in a loud one – a small but significant difference. Those that survived weighed less if they lived in noisy neighbourhoods. This might be because, as Schroeder found, mother birds visited their chicks less often and provided them with less food.
Schroeder acknowledges that she only looked at nest boxes in one noisy site, which may differ from the quiet ones in ways that have nothing to do with noise. However, she thinks that this is unlikely, since noisy nests were just as far from the sparrows’ feeding grounds as the quieter ones. And any widespread problem, like exhaust pollution, would have affected the parent birds as well as the chicks – Schroeder found that only the chicks were affected.
“If what we suggest takes place in cities too, it is likely to play an important role in the sparrow population dynamic, and is probably one cause of the dramatic population crash that we are currently observing,” says Schroeder. Indeed, even though the house sparrow has spread to cities all over the world, it has started to disappear in Western Europe and North America.
There are probably many reasons for this decline, but parental care is one of them. In a recent study, Gabor Seress from the University of Pannonia, Hungary, found that suburban sparrows provide their young with less food than rural birds, and the chicks grow smaller as a result. Schroeder’s study suggests that chronic noise could contribute to this difference.
She now wants to work out exactly why the chicks get less food amid the generators’ hubbub. Maybe the parents can’t hear them begging. Maybe the chicks don’t beg enough because they can’t hear their parents return (their eyesight is poor at an early age). Maybe the noise drives off potential insect prey. “It will be interesting to compare stress hormone levels of parent birds and chicks from nestboxes in the noisy area, with those breeding elsewhere,” she says. “It would be interesting to experiment with noise-insulated nest-boxes.”
(I wrote about how birds cope with noise for New Scientist years ago, so have a look at the feature (PDF) for some background.)
Reference: Schroeder, Nakagawa, Cleasby & Burke. 2012. Passerine Birds Breeding under Chronic Noise Experience Reduced Fitness. PLoS ONE citation tbc
Image by David Lofink | <urn:uuid:8ee7ceff-e090-4171-a93c-a1bd47902c50> | 3.515625 | 1,192 | Nonfiction Writing | Science & Tech. | 53.235782 |
Boolean algebra definition logic
(After the logician George Boole
1. Commonly, and especially in computer science and digital electronics, this term is used to mean two-valued logic
2. This is in stark contrast with the definition used by pure mathematicians who in the 1960s introduced "Boolean-valued models
" into logic precisely because a "Boolean-valued model" is an interpretation of a theory
that allows more than two possible truth values!
Strangely, a Boolean algebra (in the mathematical sense) is not strictly an algebra
, but is in fact a lattice
. A Boolean algebra is sometimes defined as a "complemented distributive lattice
Boole's work which inspired the mathematical definition concerned algebras
, involving the operations of intersection, union and complement on sets. Such algebras obey the following identities where the operators ^, V, - and constants 1 and 0 can be thought of either as set intersection, union, complement, universal, empty; or as two-valued logic AND, OR, NOT, TRUE, FALSE; or any other conforming system.
a ^ b = b ^ a a V b = b V a (commutative laws) (a ^ b) ^ c = a ^ (b ^ c) (a V b) V c = a V (b V c) (associative laws) a ^ (b V c) = (a ^ b) V (a ^ c) a V (b ^ c) = (a V b) ^ (a V c) (distributive laws) a ^ a = a a V a = a (idempotence laws) --a = a -(a ^ b) = (-a) V (-b) -(a V b) = (-a) ^ (-b) (de Morgan's laws) a ^ -a = 0 a V -a = 1 a ^ 1 = a a V 0 = a a ^ 0 = 0 a V 1 = 1 -1 = 0 -0 = 1
There are several common alternative notations for the "-" or logical complement
If a and b are elements of a Boolean algebra, we define a <= b to mean that a ^ b = a, or equivalently a V b = b. Thus, for example, if ^, V and - denote set intersection, union and complement then <= is the inclusive subset relation. The relation <= is a partial ordering
, though it is not necessarily a linear ordering
since some Boolean algebras contain incomparable values.
Note that these laws only refer explicitly to the two distinguished constants 1 and 0 (sometimes written as LaTeX
\top and \bot), and in two-valued logic
there are no others, but according to the more general mathematical definition, in some systems variables a, b and c may take on other values as well. | <urn:uuid:138b54b5-f5d2-4465-90c1-aaa1efd785bc> | 3.703125 | 601 | Knowledge Article | Science & Tech. | 38.440954 |
Perhaps the most powerful element of the regular expression syntax, backreferences allow you to load the results of a matched pattern into a buffer and then reuse it later in the expression.
In a previous example, we used two separate regular expressions to put something before and after a filename in a list of files. I mentioned at that point that it wasn’t entirely necessary that we use two lines. This is because backreferences allow us to get it down to one line. Here’s how:
s/\(blurfle[0-9]+\)/fraggelate \1 >>fraggled_files/
The key elements in this example are the parentheses and the “\1″. Earlier we noted that parentheses can be used to limit the scope of a match. They can also be used to save a particular pattern into a temporary buffer. In this example, everything in the “search” half of the sed routine (the “blurfle” part) is saved into a buffer. In the “replace” half we recall the contents of that buffer back into the string by referring to its buffer number. In this case, buffer “\1″. So, this sed routine will do precisely what the earlier one did: find all the instances of blurfle followed by a number between zero and nine and replace it with “fragellate blurfle[some number] >>fraggled files”.
Backreferences allow for something that very few ordinary search engines can manage; namely, strings of data that change slightly from instance to instance. Page numbering schemes provide a perfect example of this. Suppose we had a document that numbered each page with the notation <page n=”[some number]” id n=”[some chapter name]“>. The number and the chapter name change from page to page, but the rest of the string stays the same. We can easily write a regular expression that matches on this string, but what if we wanted to match on it and then replace everything but the number and the chapter name?
s/<page n="\([0-9]+\)" id="\([A-Za-z]+\)">/Page \1, Chapter \2/
Buffer number one (“\1″) holds the first matched sequence, ([0-9]+); buffer number two (“\2″) holds the second, ([A-Za-z]+).
Tools vary in the number of backreference they can hold. The more common tools (like sed and grep) hold nine, but Python can hold up to ninety-nine. Perl is limited only by the amount of physical memory (which, for all practical purposes, means you can have as many as you want). Perl also lets you assign the buffer number to an ordinary scalar variable ($1, $2, etc.) so you can use it later on in the code block.
More details here: http://etext.virginia.edu/services/helpsheets/unix/regex.html | <urn:uuid:b6a5eb56-8444-4ee2-8d02-d0be0fe5ffbf> | 3.5625 | 646 | Personal Blog | Software Dev. | 55.068008 |
Pub. date: 2010 | Online Pub. Date: August 17, 2010 | DOI: 10.4135/9781412959216 | Print ISBN: 9781412959209 | Online ISBN: 9781412959216| Publisher:SAGE Publications, Inc.About this encyclopedia
Fuel Cell Technology
A fuel cell is a relatively simple device for separating electrons from their atoms via a chemical process and thereby deriving electricity from the flow of electrons. Hydrogen is the best-known source of fuel cell electricity, but other elements are also viable in certain circumstances. Fuel cells are attractive because they constitute an energy process that contributes no pollution, and especially no greenhouse gases. They generate only electricity, heat, and small amounts of water. For this reason, they will continue to be prominent in discussions of our energy future. In addition, they have very high levels of potential efficiency for converting the power source to useful energy. It is not unusual for fuel cells to have efficiency rates of 40% or more; an incandescent lightbulb, by contrast, has a rate of only 5% of its energy converted to light. The other 95% is lost. William Grove, a Welsh physicist, built ... | <urn:uuid:910e97cc-60fd-48c1-8253-bb4a826b5af2> | 3.78125 | 244 | Structured Data | Science & Tech. | 44.725 |
Models expose a consistent and unified API to interact with an underlying datasource (e.g.
MongoDB, CouchDB, MySQL) for operations such as querying, saving, updating and deleting data
from the persistent storage.
Models allow you to interact with your data in two fundamentally different ways: querying, and
data mutation (saving/updating/deleting). All query-related operations may be done through the
static `find()` method, along with some additional utility methods provided for convenience.
Classes extending this one should, conventionally, be named as Plural, CamelCase and be
placed in the `models` directory. i.e. a posts model would be `model/Posts.php`.
// Return all 'post' records
// With conditions and a limit
Posts::find('all', array('conditions' => array('published' => true), 'limit' => 10));
Posts::all(array('conditions' => array('published' => true), 'limit' => 10));
// Integer count of all 'post' records
Posts::count(); // This is equivalent to the above.
// With conditions
Posts::find('count', array('conditions' => array('published' => true)));
Posts::count(array('published' => true));
The actual objects returned from `find()` calls will depend on the type of data source in use.
MongoDB, for example, will return results as a `Document` (as will CouchDB), while MySQL will
return results as a `RecordSet`. Both of these classes extend a common `lithium\data\Collection`
class, and provide the necessary abstraction to make working with either type completely
For data mutation (saving/updating/deleting), the `Model` class acts as a broker to the proper
objects. When creating a new record or document, for example, a call to `Posts::create()` will
return an instance of `lithium\data\entity\Record` or `lithium\data\entity\Document`, which can
then be acted upon.
$post = Posts::create();
$post->author = 'Robert';
$post->title = 'Newest Post!';
$post->content = 'Lithium rocks. That is all.'; | <urn:uuid:995c58eb-02fe-4d97-a161-608259d1067a> | 2.703125 | 500 | Documentation | Software Dev. | 43.397288 |
This year's update, released Sunday, is part of a study of life in the oceans that is scheduled for final publication in 2010. The census is an international effort supported by governments, divisions of the United Nations and private conservation organizations. About 2,000 researchers from 80 countries are participating.
Ausubel said there are nearly 16,000 known species of marine fish and 70,000 kinds of marine mammals. A couple of thousand have been discovered during the census.(...)
Highlights of the 2006 research included:
--Shrimp, clams and mussels living near the super-hot thermal vent in the Atlantic, where they face pulses of water that is near-boiling despite shooting into the frigid sea.
--In the sea surrounding the Antarctic, a community of marine life shrouded in darkness beneath more than 1,600 feet of ice. Sampling of this remote ocean yielded more new species than familiar ones.
--Off the coast of New Jersey, 20 million fish swarming in a school the size of Manhattan.
--Finding alive and well, in the Coral Sea, the type of shrimp called Neoglyphea neocaledonica, thought to have disappeared millions of years ago. Researchers nicknamed it the Jurassic shrimp.
--A single-cell creature big enough to see, in the Nazare Canyon off Portugal. The fragile new species was found 14,000 feet deep. It is enclosed within a plate-like shell, four-tenths of an inch in diameter, composed of mineral grains.
--A new type of crab with a furry appearance, near Easter Island. It was so unusual it warranted a whole new family designation, Kiwaidae, named for Kiwa, the Polynesian goddess of shellfish. Its furry appearance justified its species name, hirsuta, meaning hairy.
Monday, December 11, 2006
Giant Microbes! Jurassic Shrimp! Yeti Crabs! Eeeek!!!
Apparently the ocean gets a census too, I guess so that it can be more effectively gerrymandered in 2010... | <urn:uuid:05675767-2597-4215-a878-96b015eac4cf> | 3.171875 | 421 | Personal Blog | Science & Tech. | 55.040675 |
rates of change
can also be called:
How do I calculate rates?
Calculating changes through time in the geosciences
Introduction to rates
Change and time are two of the main themes in the geosciences. For example, geomorphologists study changes in landscape such as beach erosion, geochemists study chemical changes in rocks as they are weathered, climatologists study long-term changes in global and regional weather and climate. Because geologists are interested in how rapidly changes can occur, we also look at the time over which those changes took place. Combined, this creates a rate, the rapidity in which change occurs.
What is a rate?
Any change with respect to time is called a rate.
This is represented mathematically by
Where R is the rate, ΔX is the change in whatever you are looking at (it could be temperature, pressure, distance, or anything else) and Δt is the change in time. In mathematics and many science fields, Δ means "change".
ΔX = X2-X1 and Δt = t2-t1
However many students can figure it out using without these additional formulas.
There are many rates in the geosciences - plate tectonic velocities (distance over time), crystal growth rates (change in crystal size over time), river and groundwater discharge (volume change over time), decay rates (change in number of parent isotopes over time), or any variable that is divided by time.
where d = distance, t = time, R = rate and V = velocity. This is just a specific example of a rate because distance (d) is the change in position, ΔX.
How do I calculate a rate?
In 1892, the terminus of Nisqually Glacier, on the southern side of Mt. Rainier in Washington, was located 40 meters above the current position of the Nisqually river bridge. In 1951, the terminus was located 790 m above the bridge. Calculate Nisqually Glacier's rate of retreat from the bridge (in m per year) between 1892 and 1951.
The steps to answer this question are:
- Determine which changing variable is ΔX and which is Δt. When calculating a rate, one variable is always time (Δt), and it is most often easiest to pick this out. In this problem it is the time that has elapsed which is Δt. The other property that is changing is the position (the location of the terminus), so this is ΔX.
- Calculate ΔX and Δt to determine the change in the variable(s). In the glacier problem, there are two variables that change - position (ΔX) and time (Δt).
Let's begin by calculating the change in position (ΔX); we need to know the difference between the 1892 and the 1951 positions, so we should subtract:
790 m - 40 m = 750 m = ΔX
Next we need to calculate the amount of time that elapsed. In other words, how many years are there between 1892 and 1951?
1951 - 1892 = 59 years = Δt
- Calculate the rate using ΔX and Δt.
- Check to see what the units on your final number should be. In this case, we are asked to calculate a rate in meters per year. Do we have units of meters and years? Yes!If your units are not the same as what is needed at the end of the problem (for example, if we had km and years), you can visit the unit conversions module to learn how to convert units. Just don't forget to come back and finish this page (just hit the "back" button on your browser)!!
- Evaluate your answer. Does that number seem reasonable? This is one of the most important steps; if the number you had gotten was 12,700 meters per year then the glacier would have retreated more than the height of the mountain in a single year - not likely. If you had gotten .0078 meters per year, that is less than a centimeter (a quarter of an inch or so) and that would not be measurable. As it turns out, in North America glaciers typically have been retreating at rates of 3-25 m per year. Since our rate falls somewhere in the middle, it's probably reasonable.
Determining rates from a graph
Geoscientists often present data in a graph. Any graph that has time as the horizontal axis can be used to determine a rate. In these cases, the rate is the slope of the line on the graph (many of you will know this as "rise over run") or the change in the vertical axis variable divided by the change in time (on the horizontal axis).
For practice, let's take a look at the plot at the right (you can click on it to make it bigger). In 1950, population was approximately 2.5 billion people. In 2000, world population had grown to a little over 6 billion people. So, let's calculate the rate of population growth from 1950 to 2000.
Slope is the rise over the run; this is the same as our equation for a rate since the change in time on the horizontal axis and is thus the "run."One slightly confusing thing is that our change in population, ΔX, is on the vertical axis (sometimes called the y-axis,) while Δt is on the horizontal axis (often called the x-axis.) To avoid confusion, use the rate equation above or "slope is rise over run."
So the rate of population growth between 1950 and 2000 is 0.07 billion people per year (that is 70 million people added to the planet every year on average!).
Where are rates used in geology?Rates are used in a range of topics in introductory geoscience courses:
- plate tectonics
- rocks (igneous, metamorphic and sedimentary)
- Earth history
- streams and groundwater
- mountain building and erosion
- climate change
- population growth
- and almost any other chapter in your textbook.
I think I understand how to calculate rates! Take me to the practice problems!
I still need more help! Continue below to get more help.
I know the rate, this question is asking for something different!
Sometimes we have information about the rate but are asked to solve for another variable (time, distance, volume, etc.). The basic equation is still the same but you will need to rearrange it to solve for a different variable. The Math You Need, When You Need It has an entire module dedicated to rearranging equations (if you click that link, don't forget to come back and practice your newly learned steps!). The Rearranging Equations sample problems have several problems (right at the top of the page) that help you solve for distance and/or time if you know the velocity!
Resources for rates and calculating velocityReaction rates in chemistry helps students calculate reaction rates for chemical reactions.
Calculating rates of change and slope for a graph describes and explains the process of finding the slope of a function, and thus the rate. This is from M. Casco Learning Center and has some nice mathematical applets.
by Dr. Eric M. Baer, Geology Program, Highline Community College and Dr. Jennifer M. Wenner, Geology Department, University of Wisconsin Oshkosh | <urn:uuid:c845a60e-f3df-4a39-8009-fac010ed5c4c> | 3.90625 | 1,548 | Tutorial | Science & Tech. | 57.265972 |
In this section we describe the generic algorithms in the C++ Standard Library that are specific to ordered collections. These algorithms are summarized in Table 20:
Sorts only part of sequence
Partial sorts into copy
Rearranges sequence, places in order
Sorts, retaining original order of equal elements
Nth largest element algorithm
Locates nth largest element
Binary search algorithms
Searches, returning a boolean value
Searches, returning both positions
Searches, returning first position
Searches, returning last position
Merge ordered sequences algorithm
Combines two ordered sequences
Set operations algoithms
Compares two sorted sequences and returns true if every element in the range [first2, last2) is contained in the range [first1, last1)
Forms intersection of two sets
Forms difference of two sets
Forms symmetric difference of two sets
Forms union of two sets
Heap operations algorithms
Turns a sequence into a heap
Adds a new value to the heap
Removes largest value from the heap
Turns heap into sorted collection
Ordered collections can be created using the C++ Standard Library in a variety of ways. For example:
A list can be ordered by invoking the std::sort() member function.
Like the generic algorithms described in Section 13, the algorithms described here are not specific to any particular container class. This means that they can be used with a wide variety of types. However, many of them do require the use of random-access iterators. For this reason they are most easily used with vectors, deques, or ordinary arrays.
Almost all the algorithms described in this section have two versions. The first version uses operator<() for comparisons appropriate to the container element type. The second, and more general, version uses an explicit comparison function object, which we will write as Compare. This function object must be a binary predicate (see Section 3.3). Since this argument is optional, we will write it within square brackets in the description of the argument types.
A sequence is considered ordered if for every valid or denotable iterator i with a denotable successor j, the comparison Compare(*j, *i) is false. Note that this does not necessarily imply that Compare(*i, *j) is true. It is assumed that the relation imposed by Compare is transitive, and induces a total ordering on the values.
In the descriptions that follow, two values x and y are said to be equivalent if both Compare(x, y) and Compare(y, x) are false. Note that this need not imply that x == y.
As with the algorithms described in Chapter 13, before you can use any of these algorithms in a program you must include the algorithm header file: | <urn:uuid:894d559e-9da7-4171-9fad-3a3584326f8b> | 3.828125 | 579 | Documentation | Software Dev. | 31.581695 |
I’ve written before about the claim that there has been no warming for the last 16 years. This is often made by those who are skeptical – or deny – the role of man in climate change. As I mentioned in my earlier post, this is actually because the natural scatter in the temperature anomaly data is such that it is not possible to make a statistically significant statement about the warming trend if one considers too short a time interval.
The data that is normally used for this is the temperature anomaly. The temperature anomaly is the difference between the global surface temperature and some long-term average (typically the average from 1950-1980). This data is typically analysed using Linear Regression. This involves choosing a time interval and then fitting a straight line to the data. The gradient of this line gives the trend (normally in oC per decade) and this analysis also determines the error using the scatter in the anomaly data. What is normally quoted is the 2σ error. The 2σ error tells us that the data suggests that there is a 95% chance that the actual trend lies between (trend + error) and (trend – error). The natural scatter in the temperature anomaly data means that if the time interval considered is too short, the 2σ error can be larger than the gradient of the best fit straight line. This means that we cannot rule out (at a 95% level) that surface temperatures could have decreased in this time interval.
We are interested in knowing if the surface temperatures are rising at a rate of between 0.1 and 0.2 oC per decade. Typically we therefore need to consider time intervals of about 20 years or more if we wish to get a statistically significant result. The actual time interval required does vary with time and the figure below shows, for the last 30 years, the amount of time required for a statistically significant result. This was linked to from a comment on a Guardian article so I don’t know who to credit. Happy to give credit if someone can point put who deserves it. The figure shows that, in 1995, the previous 20 years were needed if a statistically significant result was to be obtained. In 2003, however, just over 10 years was required. Today, we need about 20 years to get a statistically significant result. The point is that at almost any time in the past 30 years, at least 10 years of data – often more – was needed to determine a statistically significant warming trend and yet noone would suggest that there has been no warming since 1980. That there has been no statistically significant warming since 1997 is therefore not really important. It’s perfectly normal and there are plenty of other periods in the last 30 years were 20 years of data was needed before a statistically significant signal was recovered. It just means we need more data. It doesn’t mean that there’s been no warming. | <urn:uuid:34bb0d09-d647-465c-a111-6887b7b1fb2d> | 2.90625 | 583 | Personal Blog | Science & Tech. | 48.70801 |
The Gradient Vector
The most common first approach to differential calculus in more than one variable starts by defining partial derivatives and directional derivatives, as we did. But instead of defining the differential, it simply collects the partial derivatives together as the components of a vector called the gradient of , and written .
We showed that these partial derivatives are the components of the differential (when it exists), and so there should be some connection between the two concepts. And indeed there is.
As a bilinear form, our inner product defines an isomorphism from the space of displacements to its dual space. This isomorphism sends the basis vector to the dual basis vector , since we can check both
That is, the linear functional is the same as the linear functional .
So under this isomorphism the differential corresponds to the vector
We can remove the function from this notation to write the operator on its own as
We also write the gradient vector at a given point as , where we have to remember to parse this as evaluating a function at the point rather than as applying the operator to the value .
Now, under our approach the differential is more fundamental and more useful than the gradient vector. However, there is some meaning to the geometric interpretation of the gradient as a displacement vector.
First of all, let’s ask that be a unit vector. Then we can calculate the directional derivative . But the linear functional given by the differential is the same as the linear functional . Thus we also find that . And we can interpret this inner product in terms of the length of and the angle between and :
since the length of is automatically .
The cosine term has a maximum value of when points in the same direction as so that . That is, the direction that gives us the largest directional derivative is the direction of . And then we can calculate the rate that the function increases in this direction as the length of the gradient .
So for most purposes we’ll stick to using the differential, but in practice it’s often useful to think of the gradient vector to get some geometric intuition about what the differential means. | <urn:uuid:8f09c12e-b5d8-4544-b402-8f23f98ddf08> | 3.640625 | 432 | Personal Blog | Science & Tech. | 43.294354 |
|Is there enough water on the moon to sustain future astronauts?
The question has important implications if
humanity hopes to use the Moon as a future outpost.
Last year, to help find out,
into a permanently shadowed crater near the
Moon's South Pole.
New analyses of the resulting plume from
Cabeus crater indicate more water than
previously thought, possibly about six percent.
instrument on the separate
LRO spacecraft that
measures neutrons indicates that even larger lunar expanses -- most not even permanently shadowed -- may also contain a significant amount of buried frozen water.
Pictured above from LRO, areas in false-color blue indicate the presence of soil relatively rich in
which is thought likely bound to sub-surface water ice.
Conversely, the red areas are likely dry.
The location of the Moon's South Pole is also digitally marked on the image.
How deep beneath the surface the
ice crystals permeate is still unknown, as well as how difficult it would be to mine the crystals and purify them into
I. Mitrofanov et al., | <urn:uuid:a6b071a9-0654-4ba5-bb71-555970d7ac92> | 3.8125 | 232 | Truncated | Science & Tech. | 37.963655 |
DNA: a base or an acid?
jp10 at calvanet.calvacom.fr
Wed Oct 16 17:11:53 EST 1996
> It is an acid because of the phosphate groups on the sugar-phosphate
> backbone. The bases in DNA are weak compared to the negatively charged
> phosphate groups.
Yes of course, and it is a matter of pKa, the value of which is well
under 7 for the phosphate, while the pKa of adenine and other bases is
too high, so they should carry negligible positive charges at neutral
In chromatin the negative charges of DNA are neutralized by basic
proteins, the histones. Cations, especially divalent cations (Mn, Mg,
...) are important too in the biochemistry of nucleic acids.
More information about the Cellbiol | <urn:uuid:8b7ff98f-2172-41ba-8abf-3f213ddfedeb> | 3.03125 | 183 | Q&A Forum | Science & Tech. | 58.913831 |
Tundra shrubs turning into trees as Arctic warms
Tundra is a cold, treeless region in the Arctic where tree growth is stunted by harsh weather. But shrubs and willow in part of the area have been growing upward to the height of trees in the recent decades due to warming climate, scientists say.
Roughly 30 years ago, trees were nearly unknown in the region, but about 10 per cent to 15 per cent of the land in the southern part of the northwestern Eurasian tundra, which stretches between Finland and western Siberia, is now covered by new tree-size shrubs, which stand higher than 6.6 feet, new research has found.
"What we have found essentially is that the growth of these shrubs is really linked to temperatures," said study researcher Marc Macias-Fauria of Oxford University's Biodiversity Institute.
"They are reacting to warming temperatures by growing more," Macias-Fauria was quoted as saying by LiveScience.
The change first came to the attention of scientists when nomadic reindeer herdsmen, the indigenous Nenets, said they were losing sight of their reindeer in the new trees, he said.
Until recently the shrubs in this part of the Arctic stood about 3.3 feet high, too low to obscure a reindeer.To better understand the climate dynamics associated with the increase in growth in the northwestern Eurasian tundra, Macias-Fauria and team studied information from the herdsmen's observations, temperature data, growth rings in the wood of shrubs and satellite data, including observations of how much green covers the landscape during the growing season.
The researchers, who detailed their work in the journal Nature Climate Change, found that the shrubs grew most in years with warm Julys.
To determine how much of the land is now covered by the treelike shrubs, they used high-resolution satellite images, verifying what they saw in these with trips out into the field. | <urn:uuid:48be2acc-2034-4e63-8a42-438aa00ce601> | 3.953125 | 416 | Truncated | Science & Tech. | 46.583598 |
Evolutionary Logic About Functions of the Appendix: Using Darwin to Disprove Darwin Proves Darwin
Almost two years ago, I blogged about how conclusive evidence of function had been discovered for the appendix. Now function has been discovered for the appendix. Again.
A recent news article on Yahoo.com actually frames the issue fairly well:
The body's appendix has long been thought of as nothing more than a worthless evolutionary artifact, good for nothing save a potentially lethal case of inflammation. Now researchers suggest the appendix is a lot more than a useless remnant. ... In a way, the idea that the appendix is an organ whose time has passed has itself become a concept whose time is over.So what does the appendix do? According to the article, the appendix serves as "a vital safehouse where good bacteria could lie in wait until they were needed to repopulate the gut after a nasty case of diarrhea," and "make[s], direct[s] and train[s] white blood cells."
"Maybe it's time to correct the textbooks," said researcher William Parker, an immunologist at Duke University Medical Center in Durham, N.C. "Many biology texts today still refer to the appendix as a 'vestigial organ.'"
(Charles Q. Choi, "The Appendix: Useful and in Fact Promising," LiveScience on Yahoo News (August 24, 2009).)
Incidentally, the appendix seems to pose other challenges for evolutionary arguments. As it is found in both marsupial and placental mammals, evolutionists are forced to believe that the same appendix evolved twice, independently, in a striking case of organ-level convergent evolution.
In any case, the story notes that Darwin was the one who advanced the now-rejected idea that the appendix is a useless organ:
No less than Charles Darwin first suggested that the appendix was a vestigial organ from an ancestor that ate leaves, theorizing that it was the evolutionary remains of a larger structure, called a cecum, which once was used by now-extinct predecessors for digesting food.But following Eugenie Scott's recent advice, the scientists quoted in the article are careful to not break the third commandment of Darwinism:
"We're not saying that Darwin's idea of evolution is wrong - that would be absurd, as we're using his ideas on evolution to do this work. It's just that Darwin simply didn't have the information we have now."Another story quotes the scientists similarly exonerating Darwin, stating:
"Darwin simply didn't have access to the information we have ... If Darwin had been aware of the species that have an appendix attached to a large cecum, and if he had known about the widespread nature of the appendix, he probably would not have thought of the appendix as a vestige of evolution."Oh, I get it: Using Darwin's ideas to disprove Darwin's ideas proves Darwin was right. Makes perfect sense to me. | <urn:uuid:e044f3e2-0319-4acd-8803-5dde522d750b> | 3.203125 | 606 | Personal Blog | Science & Tech. | 43.591266 |
Photography with cameras
Nikon D3x, Nikon D300, Canon 50D
Image editing with Photoshop
|Seite 1 von 6 1 2 3 4 5 6 |
|While the males feed on the nectar of various plants, the females in Central Europe prey solely on the workers of honey bees (Apis mellifera). To detect prey they deploy their visual skills as well as their strong sense of smell. When a flying honey bee is clearly identified, the attack is immediate. The bee wolf catches the prey with its front legs and, using its sting, injects poison into the uppersurface of the waist of the prey. The correct place to sting is located with special sensitive hairs. The bee cannot resist, because its own sting cannot fix onto the smooth surface of the bee wolf and is thus not able to penetrate the outer surface. The bee wolf’s sting causes spe...|
...because its own sting cannot fix onto the smooth surface of the bee wolf and is thus not able to penetrate the outer surface. The bee wolf’s sting causes speedy paralysis of the honey bee. The bee wolf then presses out nectar and body fluid from the prey with its powerful front legs and eats this immediately. The bee itself is not consumed and is subsequently dropped. Transport of the prey into the bee wolf’s nest is only to supply food for the larvae. The females occasionally also feed on nectar, which they obtain directly from flowers.
|...later the larvae (with body lengths of 3-4 mm) hatch. They increase rapidly in size . The larvae feed (starting at the lastest three days after hatching) ) on smaller aquatic animals, and are even prone to cannibalism. In water they catch floating prey with their clamp-like mouthparts (mandibles), hold them tight and swim with the living prey intact to the water’s edge. Having found a good landing point, they put their abdomen on the solid ground and move themselves backwards with tracking the prey over the shore. They crush them with their mandibles. The exoskeleton of the prey gets covered over and over again with intestinal secretions. The prey is then kneaded into a pulpy mass which can be sucked up by the larvae. This takes 2-3 minutes. Finally the larva leaves the emptied skeleton and creeps forward back into the water. Cannibalism can become so prevalent among the larvae that they p...|
|Although Thomisus onustus are a species of Araneomorphae, they do not catch prey in webs but ambush them on the flowers of solitaire growing plants. In Central Europe, these plants include Berteroa incana and heather (Erica). Here, the females are so well camouflaged that their prey run into them unawares. Males and females grab their prey - hover flies, bees, wasps, butterflies or small beetles, often considerably larger than the spider itself - with a snap of their front legs and kill them quickly with a bite in the back of the neck. |
|...y build small orb-webs (an upright web formed of threads radiating from a central point, crossed by radial links that spiral in from the edge) between branches and stems. The Tetragnatha montana lies stretched out, outside its web, waiting for the prey. If an insect flies into the web , the spider injects it with poison and the poison turns the insides of the prey into fluid. The insect is then tied up like a parcel and stored not far off from the web. The spider then starts repairing the web. If the spider gets hungry it will eat the stored prey later on.|
|Although crab spiders are classed as web building spiders, they capture prey by ambushing them without creating a web. As they are good climbers, they are also found on high plants. They benefit from their colouration in two ways. Firstly, they reflect UV light and therefore attract insects. Secondly, they are able to adapt ...|
...nefit from their colouration in two ways. Firstly, they reflect UV light and therefore attract insects. Secondly, they are able to adapt to the colour of their hunting ground (within a few days is possible) and as a result are only observed by their prey when it is too late. They grab the prey with their front legs with lightning speed and kill them by biting them in the neck.
|Philodromus dispar prey on other insects. They are fast runners and skilled hunters and do not build webs, but capture their prey on the move. It sucks out its prey insect. In the case of danger, they press themselves flat to the ground. If they are attacked, they imitate crab spiders, lifting up the first pairs of their legs and moving towards the attacker. |
|...l as in sandy riversides or dunes.
The dune robberfly reaches body lengths of 13-20 mm. The abdomen is grey; the upper surface is covered with large brown spots. The legs are long, strong, and black.
Dune robberflies live in sandy places. They prey on other insects and are very good hunters. They often sit on the bare, hot sand waiting for their prey which they catch and sting in the air.
The dune robberfly is active from June to September. The females have a ring of spikes at the end of their ovipositors which they use to make a hollow in the sand to lay their eggs in. The larvae usuall...|
|...nsects. It builds a relatively small orb-web which is often close to the ground, The web is not more than about 1.5 metres from the ground. The autumn spider is usually found upside down in the centre of its web or near the edge , waiting for prey. In case of danger or disturbance, the spider falls back into the vegetation and adopts a special posture as camouflage. At to the soil the autumn spider can often be found in the company of spiders from the family Linyphiidae.
Males survive m...|
... a number of sexually mature males appear in the vicinity of the orb-web of the female , where they wait for the female’s readiness to mate. If an insect gets caught in the female’s web, the males race towards it and the fastest spider wraps the prey in silk and offers it as a "bridal gift" to the female. While the female spider eats the gift , the successful male starts a courtship ritual during which it drums and plucks at the threads of the web to get the full attention of ...
|The rabbit hutch spider is active at night and moves back into narrow cavities in the daytime, as it is very shy The females prey on small insects (mosquitoes, flies or other species of spiders) which they either capture in their k web, or restrain on the ground. They are capable of overwhelming prey much larger than themselves likehouse spiders, for example. Males usually wander around.|
|Cleridae fly and run well. They are present on different flowering plants or on tree bark, where they prey on other insects or their larvae. Female Cleridae (depending on species) lay 28 to 42 eggs under tree bark. The hatched larvae also prey on other insects.| | <urn:uuid:f097f8fb-dc9f-49bf-9a1d-15875ac2774d> | 2.796875 | 1,502 | Knowledge Article | Science & Tech. | 69.235175 |
Research and IPM
Phenology Model Database
Western Grape Leafhopper
Scientific name: Erythroneura elegantula
Phenology models predict timing of events in an organism's development. For many organisms which cannot internally regulate their own temperature, development is dependent on temperatures to which they are exposed in the environment.Information in this database comes from published articles. It may be used in conjunction with field monitoring and a degree-day calculator.
Note: Before using a model that was not field tested in your location, you should test the model for one or more seasons under your conditions to verify that it will work for you.
Model 1 of 1
Jensen, F. L., and D. L. Flaherty. 1982. Grape Leafhopper IN Grape Pest Management. U.C. Div. Agr. Sci. Publ. #4105. pp.95-110.
Location of study: California
Method of calculation: not specified (UC IPM recommends Single Sine)
Degree-day accumulations required for each stage of development | <urn:uuid:8a7dca60-4f76-4bca-a24d-cf4089fd0443> | 3.015625 | 222 | Structured Data | Science & Tech. | 45.024134 |
In the early 1980s, when Krause first suggested to the California Academy of Sciences that an ecosystem's sounds could be analyzed as rigorously as species distributions and nutrient gradients, he was politely ignored.
"The way we've listened to the natural world, and seen the natural world, is by taking things out of context. We name it, label it, put it in a drawer. People had gone out and recorded with parabolic dishes these individual animals," Krause said. "It's much less easy to quantify holistic patterns and structures and biophonies."
A few scientists, however, heard the potential in Krause's suggestion. Others came to the idea on their own. In recent years, soundscape ecology has become a full-fledged field of study, with researchers using sound to investigate and understand natural systems.
The Purdue Soundscape Ecology Project is a leader in this research. In the image above, unexpected spatial variations in the day-to-day soundscape of a Tuscan beech forest plot can be seen. The sonic richness of a Tuscan forest's dawn chorus can be heard in the clip below. | <urn:uuid:8081cfda-a6a3-46ed-aa5e-b77c5087a57c> | 3.671875 | 230 | Knowledge Article | Science & Tech. | 48.243775 |
What Endangered and Threatened Species Were Found?
Two endangered and two threatened species on the New Jersey Department of Environmental Protection's list were found on or in the area of the Cape May County Campus site. Endangered are the eastern tiger salamander and the southern gray treefrog. Threatened species are the barred owl and the redheaded woodpecker.
Endangered species are ones that face immediate extinction from natural or human threats like predators or population expansion. Threatened species, on the other hand, are not in imminent danger of extinction but face that risk if their environments worsen. Species are often designated as endangered or threatened by a state's environmental agency despite living in abundance elsewhere in the US.
The Endangered Eastern Tiger Salamander
The eastern tiger salamander is a stocky little amphibian, 7 or 8 inches long (although one was once measured at 13 inches) with sturdy limbs and a long tail. Its skin is mostly dark brown with irregular yellowish blotches. Its habitat stretches from southern New York State south along the East Coast into Florida, westward into the Gulf States and eastern Texas, and in the Midwest from Ohio to Minnesota. It thrives near breeding ponds and pools and can live as long as 15 years. It is designated endangered in New Jersey because of human encroachment into its habitat. It is not on the U.S. list of endangered species.
The Endangered Southern Gray Treefrog
The southern gray treefrog is common in wooded, shrubby places where there is water. It ranges from central Texas eastward through the Southeast, southward into mid-Florida and up the Atlantic Coast. The amphibian is about two inches long. Its skin is gray to green in color but its hind legs are bright orange or yellow. It moves at night, preferring the shade of a tree or shrub during the day. Its call is a harsh, rapid trill. Like the salamander, this animal is endangered in New Jersey by loss of habitat. It is not on the U.S. list of endangered species.
The Threatened Barred Owl
This woodland bird is the most vocal of all owls. Its four-hoot call has been likened to who cooks for you? Barred owls stand 16-24 inches with a wingspan of 38-50 inches. They are gray-brown with big, black eyes peering from a dome-shaped head. It preys on rodents, birds, snakes, lizards, insects and amphibians. The barred owl is found in eastern and western Canada, throughout the eastern U.S. and in the Pacific Northwest south into Northern California, and in Central America. It is not on the U.S. list of threatened species.
The Threatened Redheaded Woodpecker
The only woodpecker with a completely red head, this bird is striking in its tri-colored plumage of red, white and black. About 8-10 inches long, it thrives in treed areas, orchards, farm country and groves. The redheaded woodpecker will eat seeds from backyard feeders, enjoys ripe fruit, but its preferred food is insects and their bark-deposited eggs and larvae. The bird ranges east of the Rockies from Canada to the Gulf States. It is not on the U.S. list of threatened species.
Working closely with the New Jersey Department of Environmental Protection, the college has developed an "Endangered Species Management Plan." It incorporates three main concepts to protect the viability of endangered and threatened species on the campus site:
- Redesigning the college building, altering access drives and placing barriers to prevent the salamanders and treefrogs from wandering onto roads and parking areas
- Integrating new breeding sites of standing water and small pools 2- to 4-feet deep into the campus stormwater management system
- Reforesting some open areas to provide the cover that encourages the amphibians to migrate to new and existing breeding ponds on adjacent land
Protecting The Owl And Woodpecker
The deployment of nesting boxes, an effective and cost-efficient technique for maintaining bird populations, was undertaken on adjacent county land before both birds' nesting seasons. The boxes were constructed of unpreserved materials and were placed where barred owls and redheaded woodpeckers traditionally nest. | <urn:uuid:79c70a91-b007-4cef-b05a-763b9de47db5> | 3.265625 | 883 | Knowledge Article | Science & Tech. | 49.937331 |
Actually, your last paragraph is more the case than not.
There are currently three common definitions for delineating discrete species:
1) Phenotypically different from related species (looks or acts differently).
2) Produces viable offspring in the wild.
3) Some % of genetic difference.
There are strengths to all three:
1) Very easy to ascertain and measure.
2) Most common conception of a species.
3) Genes control the first two, so genetic divergence gets to the heart of the matter.
There are also weaknesses to all three:
1) Is notorious for mis-labeling and missing species.
2) Some species which can mate and produce fertile offspring under enclosed conditions do not do so in the wild (Tigers and Lions, for instance).
3) The amount of divergence has, thus far, been completely arbitrary. If there is a certain % or patterns of mutation required in the genome, science hasn't yet discovered it.
The fuzzy definition of species, combined in the not-exactly-intuitive generational-type thinking required for understanding evolution, and the answer to your question is (at least to the best of my understanding) the following:
Yes, at some point one of our ancestors gave birth to the first Homo sapien that was somehow genetically different from its parents. However, the magnitude of the difference is probably not as great as you might think.
We've already observed our closest evolutionary cousins, the Bonobos, making basic tools through flint napping: http://www.newscientist.com/article/dn22197-bonobo-genius-makes-stone-tools-like-early-humans-did.html
It's also possible that disputes between male chimpanzees are mediated by an older female: http://www.cpradr.org/Resources/ALLCPRArticles/tabid/265/ID/121/Primates-and-Me-Web.aspx
And that both Chimpanzees and Capuchin monkeys can be taught the concept of currency (which, somewhat comedically, they then used for prostitution): http://www.nytimes.com/2005/06/05/magazine/05FREAK.html?ei=5090&en=af2d9755a2c32ba8&ex=1275624000&partner=rssuserland&emc=rss&adxnnlx=1118160068-1EGJuan4FJH1LooxHYd5/g&pagewanted=all
Then there's the everlasting impact of Koko, the Silverback Gorilla who was taught - and perfectly capable of replying in - sign language: http://en.wikipedia.org/wiki/Koko_%28gorilla%29
The idea that humans jumped onto the scene with unforeseen amounts of intelligence and capability probably isn't what happened. Obviously we are capable of constructing and using the most advanced tools on the planet, but this is after several thousand generations of innovation. The very first human might have been more intelligent (or at least had the capacity to be), but otherwise probably fit in pretty well with its parents and other relatives since the vast majority of what we learn comes from our parents and personal experience.
Then over time the number of individuals with the capacity for higher modes of thinking increased as a result of the genetic inheritance of whatever mutation created the first human. The first human, to put it simply, was successfully able to pass on their mutation which gave them our unique traits, and their offspring were also successful - until you have an entire population of humans living amongst each other. Eventually our innovative capacity lead, step by step, to our dominant position on the planet.
Even now humans are yet evolving. Lactose tolerance (the ability to consume dairy products after childhood) is a very new trait among humans (and unprecedented among all mammals) only a few hundred generations old (roughly 10,000 years) that evolved twice in separate populations of humans (North Africa and Northern Europe). Our jaws are getting progressively smaller (which is why some people have to remove their wisdom teeth to maintain a straight smile - and some people don't have wisdom teeth at all), some muscles are disappearing (the Palmaris Longus is one example - it's present in about 80% of humans), and other subtle changes are occurring.
Just don't make the mistake of equating "evolved" with "superior." Evolution is dictated by the ever-changing demands of the environments we find ourselves in, and what's beneficial today isn't guaranteed to be beneficial forever. | <urn:uuid:41ed5a92-9d11-4bb3-88e6-ad60125720ec> | 2.796875 | 955 | Q&A Forum | Science & Tech. | 40.359248 |
Chandra Reveals Cloud Disrupted By Supernova Shock
The Chandra three-color image (inset) of a region of the supernova remnant Puppis A (wide-angle view from ROSAT in blue) reveals a cloud being torn apart by a shock wave produced in a supernova explosion. This is the first X-ray identification of such a process in an advanced phase. In the inset, the blue vertical bar and the blue fuzzy ball or cap to the right show how the cloud has been spread out into an oval-shaped structure that is almost empty in the center. The Chandra data also provides information on the temperature in and around the cloud, with blue representing higher temperature gas.
The oval structure strongly resembles those seen on much smaller size scales in experimental simulations of the interaction of supernova shock waves with dense interstellar clouds (see sequence of laboratory images). In these experiments, a strong shock wave sweeps over a vaporized copper ball that has a diameter roughly equal to a human hair. The cloud is compressed, and then expands in about 40 nanoseconds to form an oval bar and cap structure much like that seen in Puppis A.
On a cosmic scale, the disruption of l0-light-year-diameter cloud in Puppis A took a few thousand years. Despite the vast difference in scale, the experimental structures and those observed by Chandra are remarkably similar. The similarity gives astrophysicists insight into the interaction of supernova shock waves with interstellar clouds.
Understanding this process is important for answering key questions such as the role supernovas play in heating interstellar gas and triggering the collapse of large interstellar clouds to form new generations of stars. | <urn:uuid:8c2fab15-9fcd-4c58-a8aa-2ae65ce06b74> | 3.6875 | 339 | Knowledge Article | Science & Tech. | 32.480029 |
The compound SQL statement.
where statement-body is:
The compound statement is used in a routine or trigger to create an environment within which variables, cursors, exception condition names and exception handlers can be declared. A number of procedural SQL statements can also be specified.
The procedural SQL statements in a compound statement are executed in sequence whenever the compound statement is executed.
The compound statement may be used wherever a single procedural SQL statement is permitted. Thus, it provides a mechanism for executing a sequence of statements in places where the syntax rules permit only a single statement to be specified.
Compound statements can be nested and the optional label value can be used to qualify the names of objects declared within the compound statement.
The label value can also be used in conjunction with the LEAVE statement to control the execution flow by exiting from the compound statement.
The compound statement can be defined as atomic by specifying ATOMIC next to the BEGIN keyword.
When a compound statement is defined as atomic, an "atomic execution context" becomes active while it, or any sub-query contained in a statement within it, is executing.
While an atomic execution context is active:
- It is not possible to explicitly terminate a transaction.
- If an SQL statement fails to execute successfully, RESIGNAL is effectively executed and any changes already successfully made can be potentially committed, depending on the error handling in effect.
If ATOMIC is specified, the ROLLBACK and COMMIT statements must not be used in the compound statement.
A compound statement which contains a declaration of an UNDO exception handler must be ATOMIC.
A compound statement without an ATOMIC or NOT ATOMIC specification is assumed to be NOT ATOMIC.
The value of label must be the same at both ends of the compound statement.
If label is specified at the end of the compound statement it must also be specified at the beginning.
If the LEAVE statement is to be used to exit the compound statement, the label at the beginning must be specified.
SQL/PSM YES Fully compliant.
Upright Database Technology AB
Voice: +46 18 780 92 00
Fax: +46 18 780 92 40 | <urn:uuid:d2f3b9c1-4f99-413c-8185-f366eaa223b3> | 2.75 | 454 | Documentation | Software Dev. | 34.091092 |
8.2 File input
All input read from non-interactive files has the same form:
file_input: (NEWLINE | statement)*
This syntax is used in the following situations:
- when parsing a complete Python program (from a file or from a string);
- when parsing a module;
- when parsing a string passed to the exec statement;
Send comments on this document to email@example.com. | <urn:uuid:733a0afb-3c18-4390-9819-f7f32a773c4c> | 2.84375 | 92 | Documentation | Software Dev. | 46.121257 |
A binary asteroid is a system of two asteroids orbiting their common center of mass, in analogy with binary stars. 243 Ida was the first binary asteroid to be identified when the Galileo spacecraft did a flyby in 1993. Since then numerous binary asteroids have been detected.
When both binary asteroids are similar in size, they are sometimes called "binary companions", "double asteroids" or "doublet asteroids". A good example of true binary companions is the 90 Antiope system. Binary asteroids with a small satellite, called a "moonlet", have been more commonly observed (see 22 Kalliope, 45 Eugenia, 87 Sylvia, 107 Camilla, 121 Hermione, 130 Elektra, 243 Ida, 283 Emma, 379 Huenna, etc.). They are also called high-size-ratio binary-asteroid systems.
Paired impact craters, such as the Clearwater Lakes in Canada, may have been formed by binary asteroids.
Several theories have been posited to explain the formation of binary-asteroid systems. Recent work suggests that most of them have a significant macro-porosity (a "rubble-pile" interior). The satellites orbiting large main-belt asteroids such as 22 Kalliope, 45 Eugenia or 87 Sylvia could have formed by disruption of a parent body after impact or fission after an oblique impact. Trans-Neptunian binaries may have formed during the formation of the Solar System by mutual capture or three-body interaction. Near-Earth asteroids, which orbit in the inner part of the Solar System, may have split by tidal disruption after a close encounter with a terrestrial planet. A possible explanation for the relatively greater occurrence of binary asteroids near or inside of Earth's orbit was described in the journal Nature (10 June 2008): this theory states that when solar energy (see YORP effect) spins a “rubble pile” asteroid to a sufficiently fast rate, material is thrown from the asteroid’s equator. This process also exposes fresh material at the poles of the asteroid. | <urn:uuid:bd17aeb8-c6cd-4ae8-93dd-f93d0c85d613> | 4.0625 | 419 | Knowledge Article | Science & Tech. | 35.377902 |
The biodiversity of the seafloor community at New Harbour was investigated to determine the structural and functional diversity of the benthic community and resurveyed over two seasons (01-02 and 02-03). A minimum of three sites, separated by at least 50m and accessed through separate dive holes were surveyed. Two 20m transect lines were laid on the seafloor within the 15-25m depth stratum ... starting from haphazardly chosen starting points. The transects were videoed using a diver-held digital video camera at a fixed height of (a) 70cm above the bottom (for the broader scale analysis of habitat structure) and (b) 40cm above the bottom (to allow for more accurate species identifications). Along one of the 20m transects, core samples were collected from five randomly chosen positions. At each position, two small sediment cores (20mm diam., 50mm deep) were collected, one to determine sediment grain size and benthic chlorophyll a content and one to determine the natural stable isotope signature of the sediment. Also at each position, one large core (70mm diam., 100mm deep) was collected to estimate the abundance and diversity of the benthic macrofauna. Additional collections include: a) three surface sediment scrapes to determine the species composition of microalgae, b) three individuals of each of the numerically dominant epibenthic species, for growth measurements and to determine the stable istope signatures and c) additional specimens of animals and plants and organic material (eg seal faeces) for isotopic analysis to provide a more complete picture of the trophic structure of the community. Algae on the undersurface of the sea-ice were sampled to determine their isotopic signature using five small cores (20mm diam., 100mm deep). Another 9 cores were obtained for the determination of chlorophyll a and species composition of sea-ice algae. Video sampling was stratified by habitat and additional footage was taken of biota in the study area for a general picture of the site. Physical background variables (sea-ice conditions, light colour and intensity) were measured at 15m depth and water currents estimated. | <urn:uuid:7dd87a53-7b8d-4cb2-95b6-cf5d2c043fba> | 2.796875 | 455 | Academic Writing | Science & Tech. | 28.673487 |
See also the
Dr. Math FAQ:
Browse High School Imaginary/Complex Numbers
Stars indicate particularly interesting answers or
good places to begin browsing.
Selected answers to common questions:
Imaginary numbers in real life.
- Complex Roots of a Quadratic Equation [10/25/1999]
If 1+i is a root of the equation z^2 + (a+2i)z + 5+ib = 0, and a and b
are real numbers, how can I determine the values of a and b?
- Conjectures vs. Hypotheses [01/12/1999]
What is the difference between the terms 'conjecture' and 'hypothesis'?
Should the Riemann hypothesis be the Riemann conjecture?
- Conjugate Roots of Complex Numbers [12/01/2000]
If you take the nth root of a complex number, is there a way to tell if
there will be any conjugate roots among the n answers?
- Convergence of Product of Sines [10/17/2003]
Prove that (sin(pi/n))*(sin(2pi/n))*...*(sin((n-1)pi/n)) = n/(2^(n-1))
for n >= 2.
- Cosine 20 Degrees [03/24/2002]
What is the exact value of cosine 20 degrees?
- Cube Root of 1 [01/07/1998]
The cube root of 1 has three roots. I know one is +1. Can you show me the
steps to find the other two?
- Cube Roots of Numbers [11/05/1997]
If you take i (sqrt(-1)), the cube root is -i, but since x^3 = i is
degree three there should be three different values of x. What are they?
- DeMoivre's Formula [08/13/1998]
Can you explain DeMoivre's Theorem?
- Derivation of Sum/Difference of Sine, Cosine, Tangent [02/16/2002]
How can I find the derivation of the sum/difference of sine, cosine, and
- Determining the Equation of a Circle [05/12/2000]
How can I determine which of five equations describes the set of all
points (x,y) in the coordinate plane that are a distance of 5 from the
- Dividing by Complex Numbers [05/04/2003]
- e^(pi*i) = -1: A Contradiction? [8/17/1996]
I know that e^(i*Pi) = -1. But squaring and taking a natural log of both
sides, you get 2*i*Pi = 0. Please explain.
- Euler Equation [01/21/1997]
What is the meaning behind e^(pi*i) = -1?
- Euler Equation [09/13/1997]
Does the Euler equation still work if we decide to work in degrees? Is it
- Euler Equation and DeMoivre's Theorem [05/18/1999]
Do you have a proof of the equation e^(i*Pi) + 1 = 0?
- Euler's Formula [01/27/1998]
Can you derive trig formulas using a combination of Euler's Equation and
the unit circle?
- Evaluating e^(i*pi) and i^i [07/25/1999]
How can I evaluate e^(ipi) and i^i?
- Exploring i [03/16/1998]
Does i^0 equal 1? What is i to any power?
- Factoring 13 with Complex Numbers [08/11/1998]
How do you show that 13 is not prime using imaginary numbers? We know
that 13 = (3 + 2i)(3 - 2i), but how do you do this in general?
- Find a Point Above a Segment [02/16/1999]
Compute segment rotation in the complex coordinates by multiplying
- Finding Roots of Complex Numbers [09/01/2005]
How do you find the nth roots of a complex number a + bi?
- Finding Roots of Polynomials with Complex Numbers [09/27/2001]
I read in the archives that you can find the roots of 3rd or higher-
degree polynomials with complex numbers...
- Finding the Square Root of a Quadratic Function [10/30/2002]
Find the square root of 3+4i.
- Find the Flaw [08/02/2001]
I don't understand where the following proof goes wrong...
- The Fourth Root of -1 [03/27/1998]
How do you find the fourth root of -1? The square root of i?
- Fractals, Complex Numbers, and Chaos [01/20/1997]
Do fractals have anything to do with complex numbers? Do they have
something to do with chaos?
- Fractional Exponents and Complex Roots [06/11/1999]
Does z^(a/b) = (z^a)^(1/b) or (z^1/b)^a?
- Functions of Imaginary Numbers [7/31/1996]
Does (ln i) itself exist? Where does e^iA = cos A + i sin A come from?
- Geometric Interpretation of Inequality [8/23/1996]
If z1 and z2 are complex numbers, interpret geometrically the inequality
| z1 + z2 | < | z1 | + | z2 |.
- Graphing Complex and Real Numbers [02/26/2003]
Since on the Cartesian plane we can only graph real zeros and real
solutions, are we truly graphing the function when we omit the complex
and imaginary zeros and solutions?
- Graphing Complex Functions [08/11/1998]
In the quadratic equation y = x^2 + 5x + 12, when y = 0 has no solutions,
where (if anywhere) do these numbers lie on the graph of this equation?
- Graphing Sums of Complex Numbers [12/06/2006]
Why is it that when two complex numbers are graphed, then the sum of
those two complex numbers is graphed (all of this on the same graph),
and then lines are drawn to connect the parts of each graph farthest
from the origin, a parallelogram is formed?
- Graph of y = (-n)^x [01/17/2005]
I am curious as to what the graph of y = (-n)^(x) would look like,
such as y = (-2)^x. My graphing calculator will not show the graph as
anything, but displays many real values in the table of values.
- History of Complex Numbers [12/12/2005]
Why were complex numbers invented?
- History of Imaginary Numbers [03/09/2001]
Who invented imaginary numbers?
- i and (-1) with Multiple Powers [08/09/2001]
What is the order in which i and (-1) should be raised when using
multiple powers? Why is it possible to obtain so many different values?
- i^i [04/03/1997]
What is i to the power of i ?
- The Imaginary Number J [09/14/2001]
One of my teachers says you cannot find the square root of a minus
number, especially minus one. I say that the square root of minus one
equals J and is an imaginary number....
- Imaginary Number Manipulations [7/10/1996]
Through some of my manipulations of the imaginary number (i), I somehow
demonstrated that -i = i. What is going on here?
- Imaginary Numbers, Division By Zero [07/03/2000]
If we can create a number system using the square root of -1, why can't
we do the same with division by 0? Could we define a number to be equal
to 1/0? Also, do imaginary numbers have any real-life uses? | <urn:uuid:f1414b40-26aa-4467-9eb1-b0796171f367> | 2.875 | 1,794 | Q&A Forum | Science & Tech. | 81.221558 |
The volcanic origin of the Azores archipelago (Portugal) gives rise to active deep sea and shallow water hydrothermal activity that affects benthic communities. Intertidal seaweed surveys were conducted at two shores affected by intense shallow water hydrothermal vents. Water temperature, acidity and salinity were monitored. Seaweed communities were found to be species poor and have a disproportionally larger number of filamentous early successional species on shores that are subject to the effect of hot and acidic freshwater of volcanic origin. There is an ecological resemblance between hydrothermally affected seaweed communities in the Azores and those affected by acid mine drainage in the UK, thus indicating that hydrothermalism can be a useful scenario for pollution studies under conditions of ocean warming and acidification.
Wallenstein F. M., Couto R. P., Torrão D. F., Neto A. I., Rodrigues A. S., Wilkinson M., in press. Intertidal rocky shore seaweed communities subject to the influence of shallow water hydrothermal activity in São Miguel (Azores, Portugal). Helgoland Marine Research. Article (subscription needed). | <urn:uuid:c87c3cbf-b9c6-45cb-9296-bb32ebe48d7c> | 2.96875 | 239 | Truncated | Science & Tech. | 20.037006 |
By Raphael G. Satter, Associated Press Writer
LONDON Deepening drought in Australia. Stronger typhoons in Asia. Floods in Latin America.
British climate scientists predict that a resurgent El Niño climate trend combined with higher levels of greenhouse gases could touch off a fresh round of ecological disasters — and make 2007 the world's hottest year on record.
"Even a moderate (El Niño) warming event is enough to push the global temperatures over the top," said Phil Jones, director of the Climatic Research unit at the University of East Anglia.
The warmest year on record was 1998, when the average global temperature was 1.2°F higher than the long-term average of 57°F. Though such a change appears small, incremental differences can, for example, add to the ferocity of storms by evaporating more steam off the ocean.
There is a 60% chance that the average global temperature for 2007 will match or break the record, Britain's Meteorological Office said Thursday. The consequences of the high temperatures could be felt worldwide.
El Niño, which is now underway in the Pacific Ocean and is expected to last until May, occurs irregularly. But when it does, winters in Southeast Asia tend to become milder, summers in Australia get drier, and Pacific storms can be more intense. The U.N.'s Food Aid Organization has warned that rising temperatures could wreak agricultural havoc.
In Australia, which is struggling through its worst drought on record, the impact on farmers could be devastating. The country has already registered its smallest wheat harvest in a decade, food prices are rising, and severe water restrictions have put thousands of farmers at risk of bankruptcy.
In other cases, El Niño's effects are more ambiguous. Rains linked to the phenomenon led to bumper crops in Argentina in 1998, but floods elsewhere in Latin America devastated subsistence farmers.
El Niño also can do some good. It tends to take the punch out of the Atlantic hurricane season by generating crosswinds that can rip the storms apart — good news for Florida's orange growers, for example.
"The short-term effects of global warming on crop production are very uneven," said Daniel Hillel, a researcher at Columbia University's Center for Climate Systems Research. "I warn against making definitive predictions regarding any one season's weather."
What is clear is that the cumulative effect of El Niño and global warming are taking the Earth's temperatures to record heights.
"El Niño is an independent variable," Jones said. "But the underlying trends in the warming of the Earth is almost certainly a result of the release of carbon dioxide into the atmosphere."
AUDIO INTERVIEW: Phil Jones, University of East Anglia
Another more immediate effect of the rising temperatures may be political.
Australian Prime Minister John Howard is already under fire for refusing to link his country's drought to global warming. In Britain, Friends of the Earth campaign director Mike Childs said the weather service's 2007 prediction "underlined the gap between the government's rhetoric and action."
Other environmental groups said the new report added weight to the movement to control greenhouse gases.
It came a day after the weather service reported that 2006 had been Britain's warmest year since 1659, and three months after Sir Nicholas Stern, a senior government economist, estimated that the effects of climate change could eventually cost nations 5% to 20% of global gross domestic product each year.
Figures for 2006 are not yet complete, but the weather service said temperatures were high enough to rank among the top 10 hottest years on record.
"The evidence that we're doing something very dangerous with the climate is now amassing," said Campaign against Climate Change coordinator Philip Thornhill.
"We need to put the energy and priority (into climate change) that is being put into a war effort," he said. "It's a political struggle to get action done — and these reports help."
Copyright 2007 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. | <urn:uuid:c75b8581-d316-44b1-97c2-dc32c4e092d1> | 2.953125 | 824 | Truncated | Science & Tech. | 44.257026 |
Science Fair Project Encyclopedia
The Living Planet
The sequel to his pioneering natural history series Life on Earth, The Living Planet was a study of the ways in which living organisms, including humans, adapt to their environments. Each of the 12 50-minute episodes (one episode less than Life on Earth) featured a different environment.
One new piece of equipment used in the series was a scuba diving suit with a large fully-enclosed faceplate, allowing Attenborough to speak (and be seen) underwater.
There was an accompanying book, and the series is available on DVD.
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:be08560f-4591-4c0d-9c5c-f387601b4ee7> | 3.3125 | 150 | Knowledge Article | Science & Tech. | 37.974508 |
The hunt for allelopathic plants
tnb1 at cornell.edu
Wed Sep 22 11:52:27 EST 1999
It seems to me that a drawback to this approach is that it may not
demonstrate allelopathy. The particulars of how you do it will be very
One false result would be if you used extract of sugar beet (i.e.
sucrose). Fungal and bacterial pathogens would multiply quickly and reduce
germination. The pathogens are already on the seeds, so sterlilization is
unlikely to be very effective. What you wuold be demonstrating here is
that simple sugars favor pathogens, and that seed rot reduces germination.
The second false result is that many allelopathic agents don't act on
For instance, the compound responsible for the classic rye allelopathy
(dibenzoxazolinone) acts on the root meritem. Rye extracts have dramatic
effects on root growth, but little or none on germination. In this case
you would fail to demonstrate allelopathy that was really there.
You can also get a false positive by using root growth, however. If your
extract is high in carbon, microorganisms will take up the carbon faster
thean will the seedling. At the same time, they will take up nitrogen so
they can make protein with the carbon. As a result, the seedling becomes
nitrogen starved. Indeed it can lose a substantial amount of its nitrogen
reserves by leaching. Avoiding this form of growth inhibition is a major
management criterion in agricultural systems using cover crop plowdowns.
Perhaps, if the system is sterilized really well, this could be avoided,
but it is not easy.
In article <7s8sj9$cso$1 at news.henryford.cc.mi.us>, "J. Kelly"
<hfcckelly at hotmail.com> wrote:
> I remember doing a lab in Plant Ecology at where we tested the effects of
> leaf rinses and leaf extracts on the germination of Jack pine seeds (pinus
> banksiana). We collected jack pine cones, placed them in an oven at low
> heat to get them to open (they are serotinous cones), and shook out the
> seeds. We placed the seeds on a layer of washed beach sand in sterile petri
> dishes. Then we moisted the seeds with a number of different solutions. We
> homogenized the leaves of wild black cherry (Prunus serotina), reindeer moss,
> and jack pine. We aslo placed the leaves of these 3 plants in large plastic
> funnels and sprayed water over them to mimic the effect of rain washing
> chemicals off the leaves. As I remember it worked quite well. Our
> instructor had an article on this, which I believe was from Ecology. You
> might try a an online literature search.
> Good Luck, Judy Kelly, Biology Dept. Henry Ford college
Dept. of Horticultural Sciences
More information about the Plant-ed | <urn:uuid:3422993b-fa93-421d-a3c8-932de269573f> | 2.75 | 656 | Comment Section | Science & Tech. | 55.035407 |
Threonine is one of the 20 most common natural amino acids on Earth. Nutritionally, in humans, threonine is also an essential amino acid.
Threonine contains two chiral centers, so there are four possible stereoisomers of threonine. It means that there are two possible diastereomers of L-threonine. However, name L-threonine is used for one single enantiomer, (2S,3R)-2-amino-3-hydroxybutanoic acid. The second diastereomer (2S,3S), which is present nature rather rarely, is called L-allo-threonine.
The threonine side chain can undergo O-linked glycosylation.
Threonine can become phosphorylated through the action of a threonine kinase. In its phosphorylated form, it can be referred to as phosphothreonine.
Foods high in threonine are cottage cheese, poultry, fish, meat, lentils, and sesame seeds. | <urn:uuid:e3f9f316-f7f2-4a6e-a591-59bc984bfede> | 3.125 | 222 | Knowledge Article | Science & Tech. | 34.4227 |
HinodeArticle Free Pass
Hinode, also called Solar-B, a Japanese-U.S.-U.K. satellite that carried a 50-cm (20-inch) solar optical telescope, a 34-cm (13-inch) X-ray telescope, and an extreme ultraviolet imaging spectrometer to observe changes in intense solar magnetic fields that were associated with solar flares and coronal mass ejections. It was launched on Sept. 23, 2006, from Japan’s Uchinoura Space Center by an M-5 rocket into a Sun-synchronous Earth orbit that kept the satellite continuously in sunlight. The name is the Japanese word for “sunrise.” Hinode discovered magnetic waves in the solar chromosphere that drive the solar wind.
What made you want to look up "Hinode"? Please share what surprised you most... | <urn:uuid:efc81403-346a-4144-baa5-713d1fffad09> | 3.203125 | 181 | Knowledge Article | Science & Tech. | 54.855929 |
| The Big One
By Cartoon: Pat Bagley, Salt Lake Tribune
Project: Cynthia Kirkeby
May 26, 2008, 06:08 PST
|© Pat Bagley, Salt Lake Tribune 2008|
The Next Big One
Since the beginning of 2008, there have already been nine "special" seismic events around the world. Ranging from a magnitude 5.2 in Illinois to a magnitude 7.9 in Eastern Sichuan, China. The damage has ranged from minor building damage with no injuries to severe damage to buildings in the Dujiangyan-Mianzhu-Mianyang area, and more than 51,000 people killed. Some of these earthquakes are following a pattern of increased seismic activity in their areas.
Questions to Ponder
- Have people in high earthquake areas become complacent about the risk in their areas?
- Does your family have an emergency kit prepared?
- Does your family have an emergency plan in case of an earthquake or other disaster?
- Do you think that your city or town is sufficiently prepared to deal with a major disaster?
- Has your town published a formal disaster plan?
Learning Links for International Earthquakes and Disaster Preparation
© Copyright 2008 by Classbrain.com
Top of Page | <urn:uuid:ad324d2e-723e-46c1-b0af-a0570abf6665> | 2.796875 | 258 | Truncated | Science & Tech. | 49.867115 |
HomePython Page 8 - Python 101 (part 7): Dinner With A Hungry Giant
String Theory (And Other Interesting Stuff) - Python
Python allows developers to logically group functions togetherinto modules, which can be imported and used by any Python program. In thisarticle, find out what a module is, learn how modules and module namespaceswork, and check out the default modules that ship with Python
Python comes with a whole bunch of built-in modules, which can substantially reduce the time you spend on development. Here's a list of the most common and useful ones (some of these are only available in Python 2.x):
The "string" module handles common string operations,
>>> import string
>>> string.center("HELLO", 80)
>>> string.split("The red wolf ate the green pumpkin", " ")
['The', 'red', 'wolf', 'ate', 'the', 'green', 'pumpkin']
while the "re" module matches regular expression via its match() and search() functions,
>>> import re
>>> re.search("at", "Batman - Dark Knight")
>>> re.findall("oo", "boom boom bang")
and the "difflib" and "filecmp" modules help in comparing strings, files and directories.
The "math" module does for numbers what the "string" module does for strings.
The "cgi", "urllib" and "httplib" modules are used to connect your Python program to the Web; the "smtplib" and "poplib" modules help in writing mail clients; the "mimetools" module helps to process MIME-encapsulated email messages; and the "xmllib", "xml.dom" and "xml.sax" modules provide the architecture necessary to handle XML data. Whew!
In case you need to find out more about a specific module - or any other Python object - consider using the dir() function, which returns a list of object attributes. | <urn:uuid:15bc3fd6-5fec-40d0-b306-a6a4a6aa8ad2> | 3.03125 | 423 | Tutorial | Software Dev. | 50.087836 |
The answer is simple: There are two “styles” of regular expressions. One of them made popular by old Unix tools like sed and grep, and another made popular by Perl. In Perl, the characters
( | ) have their special meaning – grouping and alternative. In the grep, the characters
( | ) have their ordinary meaning – they match themselves. In either case, escaping them using a backslash will change the meaning of the character.
The above example in Emacs would read
Try ReBuilder to interactively build regular expressions.
(re-search-forward "\(?:aaa\|bbb\)")not work as expected?
The EmacsLisp code is read by the so-called reader before the regular expression is compiled by the regular expression library. The elisp reader uses the same escape character as the regular expression library within strings. This has an unfortunate effect: Single backslashes will just “disappear”!
"\(?:aaa\|bbb\)"is read by the elisp reader and results in the regular expression
(?:aaa|bbb)which does not work
"\\(?:aaa\\|bbb\\)"is read by the elisp reader and results in the regular expression
\(?:aaa\|bbb\)which does work.
It can be helpful, when trying to figure out what a give regexp does or doesn’t do, and why, to use Icicles regexp searching, `
‘icicle-occur’), and so on – Icicles - Search Commands, Overview. The search hits are highlighted so that you can even see what the subgroups match. For instance, here is how this regexp is highlighted: | <urn:uuid:ee104546-63a3-4c3b-a78b-d37724b6c7ca> | 3.515625 | 362 | Documentation | Software Dev. | 55.170769 |
GirthIn graph theory, the girth of a graph is the length of the shortest cycle contained in the graph. If the graph doesn't contain any cycles, its girth is defined to be infinity.
For example, a 4-cycle (square) has girth 4. A grid has girth 4 as well, and a triangular mesh has girth 3.
The Heawood graph in the figure on the left is the smallest trivalent graph with girth 6; the Petersen graph on the right is the smallest trivalent graph with girth 5.
In common usage, girth refers to the circumference of a cylindrical object such as a tree trunk | <urn:uuid:154e8840-a74a-445d-b62f-17dd49c91504> | 3.28125 | 140 | Knowledge Article | Science & Tech. | 71.914286 |
A location is not a mere number or label. On a large scale, location information challenges application developers to work with the mathematics of movement around the not-quite-spherical surface of the Earth; on a small scale, it requires complex calculations of optimal routes based on frequent updates of rapidly changing conditions.
But the investment of that effort offers huge potential rewards for the developer who masters the mechanics and has creative ideas about what to do with the results. After all, how often does a developer get to be part of the process of figuring out the usefulness of a whole new type of data?
The tools that developers have used in any given period have revealed the data types they thought of as fundamental; the legacies of those tools betray developers lack of familiarity with data types outside their familiar space. For example, the first programmers computed almost solely with numbers. The clumsy FORMAT statement of the FORTRAN of that epoch is evidence that working with text wasnt a frequent need or a polished skill.
The next generation of programmers took for granted the convenience of "glass teletype" text output and keyboard input. But developers are still writing code that works around the clumsy conventions of that timewhen even lowercase text was a luxury, and multiple sizes and styles of font were simply unheard of outside a typesetters shop.
Today, the new data type is location, and there are many things about the location data type that make it genuinely different from other data types that programmers have come to know and understand.
A location may take the form of an ordered pair of coordinatessuch as values of a latitude and a longitudebut there are aspects of location data that make it unlike other familiar numeric or alphabetic character types. Calculating distance between two locations is not a simple matter of subtracting scalar values nor even computing vector differences: Its more like envisioning the path that a beam of light would follow through a medium with wildly varying speeds of transmission.
The "distance" between two pointsmeasured on anything but an academic straight-line basisis not a geometric question but a project management determination: Of what are usually multiple possible routes, which one presents the best expected travel time and the least dreadful worst-case scenario?
People perform surprisingly sophisticated route planning tasks all the time, and they quickly recognize a naive algorithm when they encounter one. An application that recommends a route between two points based purely on the apparent distance by road or other path, ignoringfor examplethe difference between highway and back-road speeds or the relative traffic density of different times of day, will not engage and retain the user. The state of the art in this area is rising quickly.
Location-based applications are therefore fertile ground for exploring the potential of using a Web service interface to incorporate, for instance, current information on weather, construction disruptions or other dynamic forces from data feeds that would be expensive to duplicate.
Indeed, if the voluntary sharing of information and the collaborative development of content are the hallmarks of Web 2.0, then perhaps the next step of automating that sharing would justify the label of Web 3.0. As soon as one talks of sharing location data, though, especially anything with a real-time component representing the behavior or plans of any identifiable user, the issue of privacy quickly raises concerns.
At the third annual Where 2.0 conference this coming May in San Jose, Calif., participants will doubtless explore issues that have arisen at the two prior events, such as the ownership of a users location history, the proper balance between law enforcement needs and personal privacy expectations, and the division of roles and costs between private service providers and public infrastructures.
Developers who ignore the issues and opportunities of location awareness will wind up on the outside looking in.
Technology Editor Peter Coffee can be reached at firstname.lastname@example.org.
Peter Coffee is Director of Platform Research at salesforce.com, where he serves as a liaison with the developer community to define the opportunity and clarify developers' technical requirements on the company's evolving Apex Platform. Peter previously spent 18 years with eWEEK (formerly PC Week), the national news magazine of enterprise technology practice, where he reviewed software development tools and methods and wrote regular columns on emerging technologies and professional community issues.Before he began writing full-time in 1989, Peter spent eleven years in technical and management positions at Exxon and The Aerospace Corporation, including management of the latter company's first desktop computing planning team and applied research in applications of artificial intelligence techniques. He holds an engineering degree from MIT and an MBA from Pepperdine University, he has held teaching appointments in computer science, business analytics and information systems management at Pepperdine, UCLA, and Chapman College. | <urn:uuid:27ebd28f-8208-48a0-b0f0-74f5c5dd9fbf> | 3.296875 | 962 | Nonfiction Writing | Software Dev. | 20.645719 |
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For that one, there's no way to get an equivalent term by changing just one of them (without involving fractions), so you need to change both.
3x + 2y = 16
What is the first step for the following simultaneous equation:
Do we always use the method of multiplying one of the equations so that two of the variables match in value? Unless the coeffiecient of one of the variables is 1?
You're taking away the -10, but as it's already negative then it's equivalent to you adding 10.
Ah thankyou, I did not know of this method of making a pair of variables match.
The simplest way to get one of the equations to have an equal term to the other is to double the second one.
I know the basics of solving these, but I can't seem to get the following one right: | <urn:uuid:9f2a8737-54c5-4008-87ba-2431b6b049e4> | 2.703125 | 254 | Comment Section | Science & Tech. | 68.710328 |
Inert Gases and Electron Shell Population
Date: September 2007
I was told that the inert gases are unreactive because
they are stable i.e. they have 8 electrons in their outer shell. But
that is not true for all of the inert gases, e.g. krypton. How do
you explain this?
Wow! Quite a question for a 6-8 grader!
So, I am going to give you quite an answer...
For many, many years people believed that
all of the noble gases were unreactive.
However, during the last part of the 20th
century it became clear that Xe and Kr could
participate in a few chemical reactions
(Neil Bartlett at U. British Columbia showed
that Xe could react with PtF6 in 1962).
So, although they are relatively unreactive
compared to other elements, they are not nonreactive.
As a result they are now called the *noble gases," and
they are no longer called the rare gases or the
inert gases in the scientific literature.
The stability of 8 electrons in an outer
shell is not a law of nature.
It is the Octet *Rule*, right?
A "rule" is a summary of many observations that
works for certain well-defined situations but
does not work for all cases.
Only the following elements
strictly obey the Octet Rule as far as
I am aware: C,N,O,F,Si,Ne,Ar. Other elements
may often obey it but there are exceptions.
For example, Br, P, S, Cl and I (iodine) can have
more than 8 electrons in their Lewis Dot
structures in certain compounds. B can have either
6 or 8.
Hope this helps.
The ground state electron configuration of:
bromine [Ar] +3d10, 4s2, 4p5;
krypton [Ar] + 3d10, 4s2, 4p6;
rubidium [Ar] + 3d10, 4s2, 4p6, 5s1
Your interpretation of the condition that "they have 8 electrons
in the outer shell" is a bit too constrained. The term "outer shell"
requires a somewhat broader definition. Imbedded in the definition is
an understanding that the "ns" and "np" orbitals have lower energy
than the "(n-1)d" orbitals, as you see from the series above. In the
case of rubidium, and following elements, the "5s" and "5p" orbitals
fill before the "5d". The source of your criterion (book/teacher) is
not as specific as it (could/should) be. You are commended for
observing the unstated condition on the Aufbau rules.
Unfortunately what you have been taught thus far is a simplification.
It is based on the general observation that the noble gases are inert
to chemical reactions, and the fact that we note that the general
electronic configuration of the most energetic orbitals of the noble
gases are such that the highest principal quantum numbered orbital has
its full complement of electrons. We, therefore, surmise that chemical
reactivity has everything to do with being able to fill-in these highest
principal quantum number. This is still true for Krypton which has an
electronic configuration of [Ar] 4s2 3d10 4p6. As such the highest
principal quantum number is 4 and the most energetic orbital "p" has
its full complement of 6.
A more detailed explanation of the Schroedinger Model of the Atom and
Molecular Orbital Theory gives a better rational to the inert nature
of the noble gases (as well as the existence of covalent bonds) but
this would be beyond the scope of this short explanation.
Greg (Roberto Gregorius
They do have a filled outer shell.
What is less clear is that the "outer shell" is just 8 electrons.
The 10 "d" electrons of the preceding transition-metal range might be
considered part of that outer shell.
However my CRC book shows Krypton's shell occupation to be,
from inside out, 2-8-18-8. that looks like an outer 8.
By the way, all these electron-orbit concepts do seems to have limits.
For the bigger inert gas atoms like Krypton, Xenon, and Radon,
the outer shell electrons are not totally impregnable,
they can be pried up and shared as a covalent bond by greedy halogens like
Fluorine or Chlorine.
Click here to return to the Chemistry Archives
Update: June 2012 | <urn:uuid:7464aeff-38ec-475a-87a4-506182623609> | 4.03125 | 1,018 | Q&A Forum | Science & Tech. | 59.099823 |
Filter Paper and Semipermeable Membrane
How does the filter paper of a tea bag act as a
semi-permeable membrane when the bag is placed in a cup of hot water?
Paper is made up of tiny fibers. The fibers overlap, but do not make a
completely solid barrier. Like a sweater, filter paper looks solid from a
distance, but if you look up close, paper has little holes too. Objects
larger than the holes cannot fit through (like bits of tea). Smaller
objects, like water molecules or flavor molecules, move through easily. The
fibers themselves are attracted to water too -- when put in contact with
water, they readily become wetted (coated with water), which allows water
and water-soluble flavors to move through the bag.
Hope this helps,
Actually, the filter paper of a tea bag does not act as a
semi-permeable membrane at all. It is just a simple filter
that allows water and everything that is dissolved in it, to
pass through easily, but blocks passage of the "big lumps"
like tea leaves.
By definition, a semi-permeable membrane allows selected substances to
pass through the membrane while preventing others from passing through.
In this sense, the filter paper is preventing the tea leaves from passing
through while allowing water and the tea extracts to pass back and forth
through the paper.
Greg (Roberto Gregorius)
Click here to return to the Material Science Archives
Update: June 2012 | <urn:uuid:28857d1c-ecfc-4569-bc4b-a2eb57e96dae> | 3.046875 | 325 | Knowledge Article | Science & Tech. | 45.937522 |
- Although scientists have devoted much study to pollution, for many years they neglected the interrelatedness of natural dust and the atmosphere. Recently they have come to appreciate how dust influences climate and cloud formation—and the fertilization of oceans and rain forests.
- Despite much research, the effect of dust on the atmosphere is complex and poorly understood. Even the best supercomputers running the most sophisticated models do not provide a good picture.
More In This Article
The Bodele depression at the southern edge of the Sahara is a fearsome, forsaken place. Winds howl through the nearby Tebesti Mountains and Ennedi Plateau, picking up speed as they funnel into a parched wasteland nearly the size of California. Once there was a massive freshwater lake here. Now the lake is a shrunken puddle of its former self. Across most of the landscape, there is nothing.
Or so it would seem. But as the winds sweep the ancient lake bed, which has not been inundated in much of this area for several thousand years, they carry trillions of tiny particles skyward in vast, swirling white clouds. The dust then starts a mysterious journey—or a series of mysterious journeys—that scientists are trying to better understand.
This article was originally published with the title Swept from Africa to the Amazon. | <urn:uuid:29671e8a-ca30-4134-8605-b23c7c8561a6> | 3.640625 | 268 | Truncated | Science & Tech. | 43.304289 |
By Natalya Kovalenko | VOR
It looks like we may be in for an earth-shattering explosion. A dormant super volcano appears to be stirring under the Phlegraen Fields of Naples in Italy. Rising soil temperatures and surface deformation in the area have alarmed seismologists.
In the distant past, volcanic super eruptions caused global climate change responsible for mass extinctions of plant and animal species. So far, scientists are unable to model the potential consequences of an awakening super volcano.
Latest studies show that the Phlegraen Fields have actually been swelling above sea level at a rate of 3 cm per month. Micro quakes and large amounts of gases accumulated in soil indicate that the volcano may be preparing to erupt, says Vladimir Kiryanov, Assistant Professor of Geology at the St. Petersburg University.
“The Phlegraen Fields are a super volcano. Yellowstone in the United States and Toba in Indonesia are also super volcanoes capable of spewing more than 1,000 cubic km of magma. These are catastrophic eruptions. There was a huge volcanic eruption in the Phlegraen Fields some 30,000-40,000 years ago.
Volcanic ash from that eruption is still found in the Mediterranean, Bulgaria, Ukraine, and even in Russia. We are now seeing the expansion of a magma pocket, which means that there might be an eruption at a certain time.”
Super eruptions of such magnitude may produce the so-called “volcanic winter” effect when sulfur gases and ash will reach the stratosphere and cover the globe with thick ash clouds that solar rays will be unable to penetrate. Condensed sulfur trioxides will react with moisture, forming sulfuric acid.
Downpours of sulfuric acid will hit the Earth. Scientists have obtained new evidence of a similar cataclysm following the eruption of the Toba super volcano on island of Sumatra in Indonesia about 74,000 years ago. But today, things promise to be even more devastating. Suffice it to recall the havoc wreaked by a minor increase in volcanic activity in Iceland in 2010 on air transportation over Europe.
Super eruptions occurred so rarely that it is virtually impossible to calculate the approximate time span between the first and last stages of a future potential eruption. In the 1970s, the Phlegraen Fields inflated by more than 50 cm. There were even cracks in house walls. But then the process slackened.
Apparently, the fact itself that a magma chamber is being filled with magma may or may not signal any immediate eruption. Alexei Sobisevich, laboratory chief at the Institute of Volcanology and Geophysics of the Russian Academy of Sciences, shares his view:
“It actually seems to be a long-term precursor. A magma chamber may be filled up within a span ranging from decades to centuries. Many mounts grow by 5 cm per year. This is a natural process.”
Some scientists hold that the volcanic system of the Earth is becoming increasingly tense and that underground cavities are full of magma threatening to burst out any moment. Whether this will be a super eruption or a string of smaller eruptions, we should prepare for the worst. | <urn:uuid:994993a9-33ec-44ef-9387-571a2b8381d9> | 3.953125 | 663 | Truncated | Science & Tech. | 41.799699 |
The Lyrid meteor shower is due for its annual appearance, and is expected to peak late Sunday night, April 21, and early Monday morning, April 22, over North America. Even though the near-full moon may render much of the annual show invisible to us, Space.com tells us that away from city lights, 20 meteors per hour could be visible.
The Lyrids (pronounced Lie-rids) have been observed for more than 2,500 years — during 687 B.C., Chinese records noted that “stars fell like rain”. Aside from some similar key years, notably last year, when my family scanned the skies and then joined many other enthusiasts for NASA’s Up All Night NASA Chat, and 1982, when 90 and more shooting stars were seen for a period of hours, the Lyrids have been a minor meteor shower.
Can’t watch it at the exact time? Don’t worry — astronomers tell us that meteor showers can last for hours before and after the peak time.
What is a meteor shower?
Meteors occur when the Earth passes through streams of dust and debris from ancient comets which have entered the Earth’s atmosphere. (When the comet has flown close to the sun, its dirty ice evaporated and that, in turn, caused the comet dust to spew into space.) The Lyrid meteor shower hails from the comet C/1861 G1 Thatcher, which orbits the Sun only once every 415 years, even though we see the Lyrids that result from it annually. The orbit of this comet appears to lie in the constellation Lyra, the source of the name Lyrids.
How to watch the Lyrid Meteor Shower
Meteors are best viewed with the naked eye. Sky watchers should grab a chair (ideally one with some neck support), and a blanket if it’s cold, and head outside where you can see the largest patch of night sky possible (with as little city light as possible), and look up.
Because meteor showers last for days before and after the projected peak, try to scan the skies during the surrounding days, if you can.
This American Meteor Society page is a great site for exploring more about the Lyrids and where and when to see them in your local night sky. Their Meteor Shower Caldendar lets you get ready for future meteor shows, like the popular Perseids, which will hit this year on August 11-12.
Photo: Composite of 2009 Lyrids over Huntsville, Ala. (NASA/MSFC/Danielle Moser) | <urn:uuid:ec1abf6d-6f9d-4b67-9dd4-940c2489adf8> | 3.46875 | 542 | Personal Blog | Science & Tech. | 62.807109 |
Taking all this into consideration, which punches harder, a large person or a small person? The large person has bigger muscles and more mass, but it requires more muscle power to move the greater mass so acceleration and velocity of the punch is reduced. The smaller person has smaller muscles and less mass, but the acceleration and velocity of the punch is greater. This, striking pressures of the two punches may actually be equal. The striking force of a speeding bullet and speeding locomotive may be equal, but which would you rather be hit by?
A larger person has more reach, more mass to absorb blows, and more strength. The farther a punch travels, the more time it has to accelerate, so a larger person with longer arms may generate more power. However, it takes more time to cover the longer distance, which may give the smaller person time to avoid or block the punch. John Jerome, in his work The Sweet Spot in Time, states that large, muscular athletes are generally faster than smaller, thinner people when moving about. So, in general, a large person hits with more force than a small person.
The momentum of an object is its mass multiplied by its velocity. By adding up the momentum of all individual objects in a system, the system's total momentum can be calculated. In a "closed" system, the net momentum never changes. This is a useful fact when analyzing an impact, because we know that the total momentum of the system will be the same after the impact as it was before the impact, even though the momentum of its parts may have changed. Momentum is a "vector" quantity, which means that two equal masses moving in opposite directions with the same velocity have zero net momentum.
Energy takes many forms, such as the kinetic energy of a moving mass. Energy is a "scalar" quantity, which means that two equal masses moving at the same velocity have the same total kinetic energy, regardless of their direction of movement. The kinetic energy of an object is equal to half its mass times the square of its velocity.
Energy, like momentum, is always conserved. However, sometimes it changes from kinetic energy, which is easily observed by measuring velocities and masses, to other forms that are harder to measure, most notably heat. The process of changing kinetic energy to heat is usually damaging to the material being heated. If the material is human tissue, it can be crushed, torn, or broken by the conversion of kinetic energy to heat. If the material is wood, it will break. A process that slowly or gradually converts kinetic energy to heat is usually called friction. A process that suddenly converts kinetic energy to heat is called an inelastic collision. | <urn:uuid:0be385d8-2921-4191-991d-4376b362d48b> | 3.5 | 546 | Knowledge Article | Science & Tech. | 43.405529 |
Tackling the Global Warming Challenge in a Rapidly Changing World
How is Earth changing as climate warms? Can we slow or stop climate change? The effects of global warming are generating many questions among students. In the workshop "Tackling the Global Warming Challenge in a Rapidly Changing World" we explored classroom activities that allow students to explore the impact they make on the planet and which changes can help keep Earth a livable place. These topics will be approached from a STEM perspective, helping students be objective scientists as they consider solutions to climate change while fostering a “We can do it!” attitude in the classroom.
On this page you will find links to educational resources associated with this workshop.
- Energy Choices and Climate Change, an online module (coming soon!)
- Plugged in to CO2
- CO2 How Much Do You Spew?
- Watch Where You Step, an activity from Facing the Future
- Carbon Dioxide Sources and Sinks
- Climate Classroom Activities from Windows to the Universe
- Facing the Future, sustainability education with a positive, solutions-oriented perspective
- Climate and Global Change, educational content from Windows to the Universe
- Climate Discovery, online course series for secondary science teacher professional development
- National Center for Atmospheric Research | <urn:uuid:b3b11f4a-f1e6-425e-9dd8-6bb44a5311c6> | 4.15625 | 267 | Content Listing | Science & Tech. | 22.542786 |
September 24, 2012
|The biggest point of confusion in this question is the assumption that in 13.7 billion years the universe could have grown by only 13.7 billion light-years. This assumption is false. When we talk about the universe being a certain age, we mean that the proper time measured by a clock moving with cosmic expansion reads that many years since the Big Bang. If we use coordinates based on Albert Einstein’s special theory of relativity, that assumed clock moving with expansion travels close to the speed of light and thus hardly ticks at all. Thus, the universe can get huge before clocks have measured 13.7 billion years.|
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- Much more! | <urn:uuid:14c4d822-2b02-4a7f-8f12-4dbe333d45c6> | 3.65625 | 320 | Truncated | Science & Tech. | 51.18679 |
(Submitted September 14, 1997)
I'm looking for a picture of the Apollo 15 astronaut dropping the hammer
and falcon feather that hit the ground at the same time.
Can you help?
You can find a picture of this via the Kennedy Space Center's
history pages devoted to the Apollo missions. Go to
and link to one of the image directories. The Nasa Photo Id for the
picture is S71-43788.
You'll see, unfortunately, that this image is rather fuzzy. But if you
look carefully, you can see the hammer and the feather just as they hit
the ground. If you need further assistance, you might also try KSC's
Public Affairs office. Their web site is at
This site contains some additional names, contact numbers and other
possible links that you might find useful.
You might also be able to find the picture in astronomy textbooks.
If you're desperate, there is a doctored picture illustrating
the same principle in the expanded and illustrated edition of Stephen
Hawking's 'A Brief History of Time'. See figure 2.3, but note that it
is not a picture from Apollo 15 but maybe from Apollo 11.
Jim Lochner and Allie Cliffe
for Ask an Astrophysicist
Questions on this topic are no longer responded to by the "Ask an Astrophysicist" service. See http://imagine.gsfc.nasa.gov/docs/ask_astro/ask_an_astronomer.html
for help on other astronomy Q&A services. | <urn:uuid:99ffa750-d295-4b8c-bb5f-08bdb63c5372> | 2.859375 | 328 | Q&A Forum | Science & Tech. | 59.910883 |
If we take enough consecutive integer base numbers and raise them to the same power, we have (for example):
If we then subtract these numbers orderly, pair by pair, we get another vertical row of numbers, but now there is one number less than in original series (5 versus 6 numbers):
If we repeat this process, we get:
So, in this example the end-point is 24.
Had we chosen initial raising number to be 3, the end point would be 6. With raising number 2 it would be 2 and with raising number 5 we should have 120 as the end point.
So, the rule appears to be: with raising number x we end to factorial of x.
Can anyone tell me, what is the NAME OF THIS METHOD??? (not just this example-method which produces factorials, but this pair by pair subtraction method in general).
I am very interested in this method, but have difficulties to find more information of it from internet and even from this math help forum.
I have only found one name for it (from John H Conway & Richard K Guys book "The Book of Numbers" from 1996, pages 79-89). They gave it name "difference table".
However, when I try this term in search-engines, I only find information of calculus, differentiation etc.
Please, help me! | <urn:uuid:7a9ed323-9ddc-40c9-857e-8176649a61a7> | 2.890625 | 283 | Q&A Forum | Science & Tech. | 66.507254 |
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Which of these infinitely deep vessels will eventually full up?
Why do this problem?
is an exploration into volumes of revolution. The numbers involved are awkward, which will encourage accurate and careful algebra. By thinking about the volumes and the formula students will gain an insight into the types of functions for which a volume of revolution calculation is possible.
This question involves 'awkward' numbers, so might be a good problem to use when practising careful integration. Note that the 'usual' volume of revolution formula is for revolution about the $x$ axis, whereas this problem involves revolution about the $y$ axis. Be sure that students are aware of this problem, which might be overcome in a group discussion.
What is the problem with implementing the usual volume of revolution formula?
Can students explicitly invent a curve which, when revolved, gives a depth of $1$cm when the vessel is half full?
This question is computationally involved. If your students are struggling with the numbers and algebra, focus on the first two curves. You might also change the question so that the curves pass through $(1,1)$ instead of $(2.5,10)$.
Volumes of revolution
Maths Supporting SET
Volume and capacity
Manipulating algebraic expressions/formulae
Meet the team
The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice. More information on many of our other activities can be found here.
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NRICH is part of the family of activities in the
Millennium Mathematics Project | <urn:uuid:80c54994-1cb8-469e-a404-c81f0f23cda0> | 2.953125 | 490 | Content Listing | Science & Tech. | 42.973883 |
Wildlands Mapping and Research
Questions and answers - what are wildlands and uninventoried roadless areas?
Click here for a web page explaining what wildlands are. This page also defines what inventoried and uninventoried roadless areas are and why they exist.
Studies of Wildlands by Pacific Biodiversity Institute
Pacific Biodiversity Institute has applied our extensive field-based knowledge and our spatial analysis expertise to mapping the extent and characteristics of wildlands in the western hemisphere. This year, we are launching two new wildland mapping initiatives in this area. To find out more about these specific initiatives, follow the links below.
Click here for a ten-year update of our Washington State wildland mapping project. This page contains a new report discussing the biodiversity contributions of wildlands in Washington and conservation priorities amongst wildlands in the state.
Click here to learn about our efforts to map all the wildlands in South America. This is an ambitious project with our Latin American conservation partners. Our wildland mapping project will share and disseminate information about the contribution of wildlands to global biodiversity.
Our maps of South American Wildlands are available online as PBI Webmaps. Click here to learn about PBI Webmaps, or click one of the links below to link directly to a Webmap of a South American Wildland.
These new initiatives build on over 15 years of previous research and mapping work focused on wildlands.
Starting in 1993 we mapped the roadless areas and other wildlands that are already protected as Wilderness or Park as part of a biodiversity assessment and establishment of conservation priorities for the North Cascade Ecosystem in Washington State and British Columbia. This work lead to the design of an integrated reserve network that encompasses all elements of regional biodiversity where the wildland complexes for the core of the reserve network. Beginning with this project, we took a novel approach, where we mapped roadless areas and other wildlands on all ownerships, public, private and tribal. Nature knows no borders, so why should wildland boundaries not be mapped across all ownerships? Political decisions will affect one ownership differently from another ownership, but the wildlife that depend on our wildlands do not know where one ownership begins and ends. So, at least from a conservation information and planning perspective, Pacific Biodiversity Institute believes that it is important to consider the entire landscape when defining and mapping roadless areas and wildlands.
Soon after the North Cascades project was finished we went on to map of all the remaining unprotected and protected wildlands in Washington State. We published a report (PDF), Unprotected Wildlands of Washington State in 1998 based on this work. Soon after this was finished, we mapped the unprotected and protected wildlands in Oregon, in a partnership with the Oregon Natural Resources Council. A map of Oregon's wildlands resulted from this project.
Soon after this, the Sierra Club asked us for help in mapping the remaining wildlands across the eight western states that Lewis and Clark traversed during their trek in the first part of the 19th century. We produced a series of maps for them, which were published in Sierra (their magazine and used in a variety of other venues celebrating the Lewis and Clark Expedition. A map of the wildlands in all 8 northwestern states with Lewis and Clark's route resulted from this project.
And a year later, Pacific Biodiversity Institute was commissioned by the Pew Wilderness Center to map the remaining wildlands on four federal ownerships (National Forest, BLM, National Park and National Wildlife Refuge) across the entire nation and its territories. This lead to another series of maps covering the entire nation and more detailed maps for each state. You can purchase hard copies of these maps on our maps and products page.
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Winthrop, WA 98862 509-996-2490 | <urn:uuid:22f4fee4-6c4a-4376-adcd-b17c276e158a> | 3 | 792 | Content Listing | Science & Tech. | 32.589653 |
Humans caused the Ozone H*** in the Earth's Atmosphere. Who says the Earth and its atmosphere are too big for Humans to influence? Humans have raised the total parts per million ("ppm") of CO2 in the Earth's atmosphere to 389 ppm. That is 39 ppm above the so-called thermal runaway tipping point. Above 350ppm, the Earth's average surface temperature is uncontrollable (ie: in thermal runaway). At that level, no natural nor artificial process can keep the average temperature on the Earth's surface from increasing. The melting glaciers on Mt. Kilimanjaro are the canaries in the coalmine here. Take a look at the rest of the photos and you'll see the effects of human generated Global Warming. | <urn:uuid:7ca5ab97-ffaa-4f0c-a921-9a231a441cbd> | 3.46875 | 153 | Personal Blog | Science & Tech. | 57.8548 |
Ulysses was the first spacecraft to study our Sun's poles.
Ulysses was launched aboard the Space Shuttle Discovery STS-41 mission (right).
The spacecraft used Jupiter's powerful gravity to hurl it into an orbit that couldn't be reached with conventional rocket power.
Ulysses was the first spacecraft to fly by the Sun's polar regions.
Ulysses was launched by the Space Shuttle Discovery.
Ulysses was built by the European Space Agency, which managed it in cooperation with NASA. | <urn:uuid:d0821678-f8fc-4be9-a12e-9710fe31ef24> | 3.953125 | 107 | Structured Data | Science & Tech. | 52.1325 |
Images: http://www.livescience.com/20817-images ... -dock.html
Debris floating around the ocean and coming to a new place isn't an unknown phenomenon. In this case, a dock, ripped forcibly from the shore of a Japanese town during the tsunami of 2011, ended up floating (perhaps along the north Pacific gyre?) to its resting place on a beach in Oregon. In addition to being a monument to the far-flung effects of such devastating loss of life and well-being, it was a vessel to life from the Japanese shore, life which survived the precarious 14-month journey. Ark or trojan horse, the article title taunts. Boon to the life on it, or a threat to the ecosystem around it.
Last February, I was only a couple of miles away from the beach (Agate Beach) where it landed, visiting Newport for the day. The dock must have crashed near the lighthouse that appeared close to the beach where I stood, though it was miles distant. While there, I visited went to the Rogue brewery and, more relevant to the story, the Hatfield Marine Science Center. The Oregon Coast Aquarium is nearby, and certainly has more in water volume and biomass, but the Hatfield Marine Science Center has a visitor's center staffed by experts and students, with exhibits that are both interesting and cool. (Escaping octopus, here's a shout out!) There was a lot about preserving the ecosystem of the coast, of the various vectors that can affect it (pollution, invasive species, so on). There was also a lot about the diversity of the ecosystem, the life that inhabit it and make it a system of life. They were ready for a lot. So I looked them up.
And it turns out they had something to say about it.
(Glossed fouling communities for convenience.)http://oregonstate.edu/ua/ncs/archives/2012/jun/floating-dock-japan-carries-potential-invasive-species wrote:“This float is an island unlike any transoceanic debris we have ever seen,” said John Chapman, an OSU marine invasive species specialist. “Drifting boats lack such dense fouling communities, and few of these species are already on this coast. Nearly all of the species we’ve looked at were established on the float before the tsunami; few came after it was at sea.”
What some of the commenters on the NPR article missed, and what I certainly did, was how unique a dock is. It already had much of that life on it, life which depends on the dock for an ecosystem. The ships - they don't bring this sort of life across, at least not so densely.
Anyway, there's a lot to this story. It's huge in implications, whether you want to focus on the dock as an ecosystem, on the effects on other ecosystems, on the continuing effects of the tsunami, on ocean currents - what do you find interesting about it? | <urn:uuid:03ab2270-b34c-4b61-b934-8e841d7a924f> | 3.109375 | 633 | Comment Section | Science & Tech. | 57.521824 |
This lovely critter is Hurdia victoria, which terrorized Cambrian seas 500 million years ago. Since being fossilized squished Hurdia into paleo-roadkill, scientists have only just reconstructed it from bits and pieces of the Burgess shale already in museum collections.
Hurdia, a primitive arthropod, was pretty monstrous for the time – up to a foot and a half long. It had a toothy circular jaw with little claws, compound eyes and a giant head carapace. Scientists think it might have lurked along the ocean floor, using its monstrous head to funnel trilobites to their doom. | <urn:uuid:be0a052b-6c7a-4078-8ed8-c6a51e058c67> | 2.984375 | 131 | Personal Blog | Science & Tech. | 47.353 |
ZOOM procedure displays part of an
image from the current window enlarged in a new ("zoom") window. The cursor is used to mark the center of the zoom area, and different zoom factors can be specified interactively.
This routine is written in the IDL language. Its source code can be found in the file
subdirectory of the IDL distribution.
After calling ZOOM, place the mouse cursor over an image in an IDL graphics window. Click the left mouse button to display a magnified version of the image in a new window. The zoomed image is centered around the pixel selected in the original window. Click the middle mouse button to display a menu of zoom factors. Click the right mouse button to exit the procedure.
Using ZOOM with Draw Widgets
Note that the ZOOM procedure is only for use with IDL graphics windows. It should not be used with draw widgets. To obtain a zooming effect in a draw widget, use the CW_ZOOM function.
Set this keyword to make the zoom window track the mouse without requiring the user to press the left mouse button. This feature only works well on fast computers.
Use this keyword to specify the zoom factor, which must be an integer. The default zoom factor is 4.
Set this keyword to use bilinear interpolation. The default is to use pixel replication.
Set this keyword to keep the zoom window after exiting the procedure.
Normally, if ZOOM is called with KEEP and then called again, it will use the same window to display the new zoomed image. Set the NEW_WINDOW keyword to force ZOOM to create a new window for this purpose.
Use this keyword to specify the X size of the zoom window. The default is 512.
Use this keyword to specify the Y size of the zoom window. The default is 512.
Set this keyword to a named variable that will contain the index of the zoom window. KEEP must also be set. If KEEP is not set, ZOOM_WINDOW will contain the integer -1. | <urn:uuid:0b21fcdd-ca8f-4cbc-b8ce-8fa93f07645a> | 3.375 | 434 | Documentation | Software Dev. | 62.633529 |
In this remarkable infrared skyscape of interstellar
clouds adrift in the
high flying constellation Cygnus,
the eye is drawn to the Cocoon Nebula.
Also known as IC5146, the dusty star forming region
is shown in blue hues in
the Herschel Space Observatory
false color image,
at wavelengths more than 100 times longer than visible red
And while visible light images
Cocoon nebula at the end of
long dark nebula Barnard 168, Hershel's
finds the cosmic
Cocoon punctuating a trail of filamentary clouds of glowing dust.
The dusty filaments have widths that suggest they are formed as
shockwaves from exploding stars travel through the medium,
sweeping up and compressing the
dust and gas.
also indicate stars are forming along
the dusty filaments.
The Cocoon Nebula
itself is about 15 light-years wide and 4,000 light-years
SPIRE & PACS Consortia,
Doris Arzoumanian (CEA Saclay), | <urn:uuid:d2653b05-91f1-440a-ae23-d7b29a465e74> | 3.328125 | 223 | Knowledge Article | Science & Tech. | 30.47 |
Cape Verde Hurricanes
The Cape Verde region is a set of islands just off western Africa. Hurricanes that form in this region are referred to as Cape Verde storms. These hurricanes have a long trajectory over warm oceans — which are ideal conditions for hurricane intensification. Many Cape Verde storms move through the Caribbean and then enter the Gulf of Mexico or affect the East Coast. Others curve north into the open Atlantic. Cape Verde storms are often extremely intense hurricanes, because they have a long time to develop before they reach the US mainland.
See Climate Central's Hurricane feature for more information. | <urn:uuid:2df282e5-5911-4b6e-a621-f5b3eaae9fe8> | 3.40625 | 121 | Knowledge Article | Science & Tech. | 32.556311 |
Liquid fuel combustion provides a major portion of the world's energy supply. In most practical combustion devices, liquid burns after being separated into a droplet spray. Essential to the design of efficient combustion systems is a knowledge of droplet combustion behavior. The microgravity environment aboard spacecraft provides an opportunity to investigate the complex interactions between the physical and chemical combustion processes involved in droplet combustion without the complications of natural buoyancy.
Launched on STS-83 and STS-94 (April 4 and July 1, 1997), the Droplet Combustion Experiment (DCE) investigated the fundamentals of droplet combustion under a range of pressures (0.25 to 1 atm), oxygen mole fractions (<0.5), and droplet sizes (1.5 to 5 mm). Principal DCE flight hardware features were a chamber to supply selected test environments, the use of crew-inserted bottles, and a vent system to remove unwanted gaseous combustion products. The illustration above shows the internal apparatus located inside the test chamber. The internal apparatus contained the droplet deployment and ignition mechanisms to burn single, freely deployed droplets in microgravity. Diagnostics systems included a 35-mm high-speed motion picture camera (see the following sequence of photos) with a backlight to photograph burning droplets and a camcorder to monitor experiment operations. Additional diagnostics included an ultraviolet-light-sensitive CCD (charge couple discharge) camera to obtain flame radiation from hydroxyl radicals (see the final figure) and a 35-mm SLR (single-lens-reflex) camera to obtain color still photographs of the flames.
Droplet growth, deployment, and burning sequence from a 35-mm high-speed camera.
The DCE experiments, which were carried out during the Microgravity Science Laboratory (MSL-1) mission in Spacelab, burned n-heptane droplets in helium-oxygen test gases and identified three regimes of droplet combustion. Droplets burned for as long as 20 seconds, much too long a time to be studied in Earth-bound facilities. The first regime was the quasi-steady regime, a fairly well documented regime in which the droplets and flames decrease linearly with time until extinction. The extinction size can be related to the chemical kinetics of combustion. A much less well documented regime (flame radiation) occurred when sufficiently large droplets and low oxygen levels were used.
Extinction occurred soon after ignition because of the large radiation heat losses from the flames. Finally, another less well documented regime (droplet disappearance) occurred when oxygen levels were sufficiently high. A flame would persist for a short time after the droplet had completely vaporized and would extinguish at a nonzero flame radius. This regime leaves behind a small vapor cloud that might be responsible for combustion inefficiencies in practical combustion systems.
Professor Forman A. Williams of the University of California, San Diego, and Professor Frederick L. Dryer of Princeton University served as the principal investigator and coinvestigator, respectively, for the DCE experiments. The DCE hardware was designed and built at the NASA Lewis Research Center.
The experiment results will aid in reducing air pollution, conserving fuel energy sources, and improving fire safety. Extinction and soot-generation phenomena will help researchers to determine the best way to build fire protection systems as well as help designers to design efficient combustion systems for space that are low in unwanted combustion product pollutants.
Lewis contacts: Dr. Vedha Nayagam (Project Scientist) (216)
and John Haggard (Project Manager), (216) 433-2832,
Author: Dr. Vedha Nayagam
Headquarters program office: OLMSA
Programs/Projects: HEDS, Microgravity Science, STS-83, STS-94, MSL-1, MSL-1R
Table of Contents
Last updated April 15, 1998, by Nancy.L.Obryan@nasa.gov
Responsible NASA Official:
Point of contact for NASA Glenn's Research & Technology reports:
Web page curator:
Wyle Information Systems, LLC | <urn:uuid:79816e0b-6964-4257-9726-9136001bc8cc> | 3.65625 | 849 | Knowledge Article | Science & Tech. | 31.115 |
Tue, Oct 16, 2012 -- 10:00 AM
Coral Reefs Under ThreatDownload audio (MP3)
Recent studies show that coral cover along Australia's Great Barrier Reef has shrunk by half since the mid '80s as warmer seas, storms and starfish colonies kill off organisms. We'll discuss the health and preservation of these fragile ecosystems.
Host: Michael Krasny
- Jen Smith, assistant professor at the Scripps Institution of Oceanography at UC San Diego
- Michael Webster, executive director of the Coral Reef Alliance, a conservation non-profit
- Terrence Gosliner, senior curator and dean of science and research collections at the California Academy of Sciences
Exploring Corals of the Deep by KQED Quest
A Flash enabled device is required to view this video
Also, please note that your comments could be read on air. We may edit them for clarity or brevity, and we will use only your first name to identify you on the air. | <urn:uuid:aa969847-b868-4047-80ac-0b9dd0e79b65> | 2.84375 | 202 | Truncated | Science & Tech. | 31.346579 |
Section: Linux Programmer's Manual (3) Updated: 2010-09-20 Local index
asin, asinf, asinl - arc sine function
double asin(double x);
float asinf(float x);
long double asinl(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see
_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
function calculates the principal value of the arc sine of x;
that is the value whose sine is x.
On success, these functions return the principal value of the arc sine of
in radians; the return value is in the range [-pi/2, pi/2].
is a NaN, a NaN is returned.
is +0 (-0),
+0 (-0) is returned.
is outside the range [-1, 1],
a domain error occurs,
and a NaN is returned.
for information on how to determine whether an error has occurred
when calling these functions.
The following errors can occur:
- Domain error: x is outside the range [-1, 1]
is set to
An invalid floating-point exception
The variant returning
also conforms to
SVr4, 4.3BSD, C89.
This page is part of release 3.27 of the Linux
A description of the project,
and information about reporting bugs,
can be found at
- RETURN VALUE
- CONFORMING TO
- SEE ALSO
This document was created by
using the manual pages.
Time: 21:41:57 GMT, April 16, 2011 | <urn:uuid:e3429646-ceba-400b-afb4-0ae067276580> | 2.734375 | 381 | Documentation | Software Dev. | 64.8645 |
BY EMILY ORLEY
Daily Staff Reporter
Published April 16, 2009
Nuclear power, known more for its destructive capabilities than its energy potential, has been a topic of recent discussion around the country as a potential alternative to foreign oil. And three researchers at the University are among those spearheading the push for this alternate, albeit controversial, energy source.
More like this
Gary Was, director of the Michigan Memorial Phoenix Energy Institute and Walter J. Weber, Jr., professor of Sustainable Energy, Environmental and Earth Systems, have been working to improve the materials used in nuclear reactors.
Nuclear reactors are made of stainless steel chrome that have relatively long functional lives, but Was is working to make further advancements in the technology to avoid preventable issues like coercion and cracking, which he said affect reactors' productivity.
“These are really aggressive environments,” Was said, “and you have to understand (the reactor’s) behavior in order to tweak the materials.”
Was has been focusing his research on grain boundary engineering — work that tailors properties to be more resistant and in turn improves their behavior.
Was said many people have reservations about the implementation of nuclear fission as an alternate energy source because of its radioactive nature. But if he can improve the quality of materials used to build nuclear reactors, Was said he believes it will become a more widely accepted resource.
In a nuclear reaction, the nucleus of an atom splits and produces free neutrons. These neutrons then make contact with other atoms, repeating the process. Each time, increasing amounts of neutrons are released, creating a chain reaction. This process produces massive amounts of energy that can be controlled in a nuclear reactor.
However, because the energy produced is so volatile, there is fear that if a nuclear reactor is not built correctly, or the materials are not of high enough quality, some of the hazardous, radioactive materials could escape into the environment.
The largest nuclear accident of this nature in the U.S. occurred in 1979 at the Three Mile Island Nuclear Generatingtation in Dauphin County, Pa., where reactor coolant escaped, releasing radioactive noble gas into the air.
While the incident at Three Mile Island has burned a negative connotation of nuclear energy into the national zeitgeist, Was argues that this incident actually serves to support the argument for increased research on nuclear energy.
“To most of the people in the nuclear field, (Three Mile Island) was the best example of the safety of nuclear energy,” Was said. “But the public at large took a long time to realize that.”
Was said that while Three Mile Island was a terrible situation, there were no major consequences. The event demonstrated that even if the system fails, reactors are efficient enough to contain the toxins and prevent widespread harm, he said.
“The safety record that has been built up is really phenomenal,” Was said. “It really can’t be approached by any other industry.”
While Was praised the safeguards that are already in place, he said his work is to ensure that there are no accidents like Three Mile Island in the future.
Prof. William Martin, chair of Nuclear Engineering and Radiological Sciences, has been working in a field called computational particle transport. His focus, he said, is on the simulation of radiation transport for applications in nuclear reactor and shielding design, as well as cancer treatment planning.
“Basically the reactor analyst or shielding analyst or radiation oncologist needs to know where the radiation is going and where it is absorbed and where does it leak out,” he said.
Martin, along with multiple graduate students, has been using stochastic simulation — which simulates particle tracks and collisions on a computer — in his research. With this, researchers can model complex systems of nuclear reactions. | <urn:uuid:48a4de72-ee75-451e-9d34-0181bc86a934> | 3.140625 | 790 | Truncated | Science & Tech. | 34.215421 |
State of the Climate
The State of the Climate is a collection of monthly summaries recapping climate-related occurrences on both a global and national scale.
- Global Analysis — a summary of global temperatures and precipitation, placing the data into a historical perspective
- Upper Air — tropospheric and stratospheric temperatures, with data placed into historical perspective
- Global Snow & Ice — a global view of snow and ice, placing the data into a historical perspective
- Global Hazards — weather-related hazards and disasters around the world
- El Niño/Southern Oscillation — atmospheric and oceanic conditions related to ENSO
- National Overview — a summary of national and regional temperatures and precipitation, placing the data into a historical perspective
- Drought — drought in the U.S.
- Wildfires — a summary of wildland fires in the U.S. and related weather and climate conditions
- Hurricanes & Tropical Storms — hurricanes and tropical storms that affect the U.S. and its territories
- National Snow & Ice — snow and ice in the U.S.
- Tornadoes — a summary of tornadic activity in the U.S.
- Synoptic Discussion — a summary of synoptic activity in the U.S.
Global Summary Information - April 2013
April 2013 global temperatures were 13th highest on record
Year-to-date eighth warmest period on record; North American snow cover extent third largest on record.
The globally-averaged temperature for April 2013 was the 13th warmest April since record keeping began in 1880. April 2013 also marks the 37th consecutive April and 338th consecutive month with a global temperature above the 20th century average.
Many areas of the world experienced higher-than-average monthly temperatures, including southern Europe, central Asia, the Russian Far East, southwestern Australia, southern Argentina, and western Greenland. Meanwhile, most of North America, northern and western Europe, northeastern Asia, central South America, and much of equatorial Africa were notably below average.
Global temperature highlights: April
- The combined average temperature over global land and ocean surfaces during April was the 13th highest on record for April, at 57.64°F (14.22°C) or 0.94°F (0.52°C) above the 20th century average. The margin of error associated with this temperature is ±0.14°F (0.08°C).
- April marked the 37th consecutive April and 338th consecutive month with a global temperature above the 20th century average. The last below-average April temperature was April 1976 and the last below-average temperature for any month was February 1985.
- The global land temperature was the 17th warmest April on record, at 1.28°F (0.71°C) above the 20th century average of 46.5°F (8.1°C). The margin of error is ±0.20°F (0.11°C).
- Some national highlights are included below:
- Australia had its fifth warmest April monthly maximum temperature on record since national records began in 1900, at 2.95°F (1.64°C) above the 1961–1990 average. At the state level, Western Australia reported its third highest monthly maximum temperature and fifth highest monthly minimum temperature.
- The average April temperature across the United Kingdom was 2.0°F (1.1°C) below the 1981–2010 average, tying with 2012 as the coolest April since 1989.
- The average April temperature across South Korea was 3.4°F (1.9°C) below the 1981–2010 average, marking the third coldest April since national records began in 1973. The average maximum temperature was also third lowest, while the average minimum temperature was second lowest on record.
- For the ocean, the April global sea surface temperature was 0.79°F (0.44°C), above the 20th century average of 60.9°F (16.0°C), tying with 2001 and 2009 as the seventh warmest for April on record. The margin of error is ±0.07°F (0.04°C).
- Neither El Niño nor La Niña conditions were present across the central and eastern equatorial Pacific Ocean during April, with sea surface temperatures below average in the far eastern equatorial Pacific. According to NOAA's Climate Prediction Center, neutral conditions continue to be favored over the next few months.
Precipitation highlights: April
- As is typical, monthly precipitation varied greatly across the globe during April. Record wetness was observed over part of the north central United States, eastern Burkina Faso, and part of eastern Russia. Record dryness was scattered across several locales around the globe, including northern Chile, central Colombia, southeastern Egypt, and part of northern Sudan.
- Following the declaration of drought conditions in March across much of New Zealand, more than double average April rainfall was recorded in the upper South Island and Tauranga. Motueka received 267 percent of its average April rainfall, with almost half of this occurring in a single day.
Polar ice highlights: April and Seasonal
- According to data from the Rutgers Global Snow Lab, the Northern Hemisphere snow cover extent for April was the ninth largest in the 47-year period of record and the largest since 1996. The April snow cover extent was 12.4 million square miles, 0.8 million square miles above the 1981–2010 average of 11.6 million square miles. Above-average snow cover was present for both Eurasia and North America, which had their 19th and 3rd largest April snow cover extents on record, respectively.
- According to data from the National Snow and Ice Data Center, the average April Arctic sea ice extent was 5.55 million square miles, approximately 150,000 square miles (2.6 percent) below the 1981–2010 average of 5.70 million square miles, resulting in the seventh smallest monthly April extent on record.
- Antarctic sea ice extent was 3.12 million square miles, 260,000 square miles (9.1 percent) above the 1981–2010 average of 2.86 million square miles. This marked the fifth largest April Antarctic sea ice extent on record.
Global temperature highlights: Year-to-date
- The first four months of 2013 (January–April) tied with 2009 as the eighth warmest such period on record, with a combined global land and ocean average surface temperature of 1.01°F (0.56°C) above the 20th century average of 54.8°F (12.6°C). The margin of error is ±0.18°F (0.10°C).
- The January–April worldwide land surface temperature was 1.71°F (0.95°C) above the 20th century average, making it the 10th warmest such period on record. The margin of error is ±0.38°F (0.21°C).
- The global ocean surface temperature for the year-to-date was 0.76°F (0.42°C) above average, making it the eighth warmest such period on record. The margin of error is ±0.09°F (0.05°C). | <urn:uuid:4ad8bfdd-8410-4327-be70-eed6232095f3> | 3.203125 | 1,509 | Knowledge Article | Science & Tech. | 56.158368 |
Want to stay on top of all the space news? Follow @universetoday on Twitter
There is a total of five Lagrangian points. L2 is the point that lies on the line defined by the two large masses, beyond the smaller of the two. At this point the gravitational forces of the two large masses balance the centrifugal effect on the smaller mass.
The three collinear Lagrange points were first discovered by Leonhard Euler around 1750. In 1772, mathematician Joseph Lagrange was working on the three-body problem, he had set out to discover an easy way to calculate the gravitational interaction between arbitrary numbers of bodies in a system. What he eventually ended up were the five Lagrangian points. These points are the five positions in an orbit where a small object affected only by gravity can be stationary(or theoretically close to it) relative to two larger objects. The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to rotate with them. They can be equated to geostationary orbits in that they allow an object to be in a fixed position in space rather than an orbit in which its relative position changes continuously. These points are the stationary solutions for the circular restricted three-body problem. If you have two massive bodies in circular orbits around a common center of mass, then there are five positions in space where a third body of much smaller mass could be placed and the third body would maintain its position relative to the two massive bodies.
L2 is the point on the far side of a second body in a system. In the Earth/Sun system, L2 is on the side of Earth that is farthest from the Sun. Normally an object on that side of the Earth would have an orbital period that is greater than Earth’s, but the Earth’s gravitational pull changes that orbit making it roughly equal to Earth’s.
The L2 point for the Sun-Earth system is a good spot for space-based observatories. Because an object around it will maintain the same orientation with respect to the Sun and Earth, making shielding and calibration much simpler. It is slightly beyond the reach of Earth’s shadow, so solar radiation is not completely blocked. The Wilkinson Microwave Anistrophy Probe, Herschel Space Observatory, and the Planck Space Observatory are in varying orbits at this point. In the future, the Gaia Probe and the James Webb Space Telescope will be parked in orbit at the Earth/Sun L2 point. The improved technology of the James Webb may enable greater study of extrasolar planets.
We have written many articles about L 2 for Universe Today. Here’s an article about deadly asteroids stuck in Earth’s Lagrangian points, and here’s an article about Lagrangian points.
We’ve also recorded an episode of Astronomy Cast all about Lagrange Points. Listen here, Episode 76: Lagrange Points. | <urn:uuid:61fd8e33-f7fc-42c1-943d-bee85615364d> | 4.46875 | 615 | Knowledge Article | Science & Tech. | 45.688626 |
This chapter uses some specialized terms. Here are some
- base table
- A real table in a FROM list. In queries that involve "virtual"
tables such as views and derived tables, base tables are the underlying tables
to which virtual tables correspond.
- derived table
- A virtual table, such as a subquery given a correlation name or a view.
For example: SELECT derivedtable.c1 FROM (VALUES ('a','b'))
- equality predicate
- A predicate in which one value is
compared to another value using the = operator.
- equijoin predicate
- A predicate in which one column is compared to a column in another table
using the = operator.
- A predicate is optimizable if it provides a
starting or stopping point and allows use of an index. Optimizable predicates
use only simple column references and =, <, >, +, >=,
and IS NULL operators. For complete details, see What's optimizable?. A synonym for optimizable is indexable.
- A WHERE clause contains boolean expressions that can be linked together
by AND or OR clauses. Each part is called a predicate.
For example: WHERE c1 =2 AND c2 = 5 contains two predicates.
- Sargable predicates are a superset of optimizable
predicates; not all sargable predicates are optimizable, because sargable
predicates also include the <> operator. (Sarg stands
for "search argument.") Predicates that are sargable but not optimizable
nevertheless improve performance and allow the optimizer to use more accurate
In addition, sargable predicates can be pushed down (see Predicates pushed into views or derived tables).
- simple column reference
- A reference to a column that is not part of an expression. For example, c1 is a simple column reference, but c1+1, max(c1), and lower(c1) are not. | <urn:uuid:53936434-59f7-490c-a2f3-0bacfc1df6f5> | 3.171875 | 419 | Documentation | Software Dev. | 30.5125 |
Photo: Adelle & Justin (Flickr)
How? And Why?
A listener wrote to A Moment of Science about a fascinating phenomenon she noticed when heating water for tea in a microwave oven.
She would take the cup of water out of the microwave just as bubbles started to form in the water. But when she lowered a tea bag into the cup, the water would start to boil!
How, she asked, could this happen after she had removed it from the oven, and why did it boil only when she put the tea bag in?
On The Stove
The large bubbles in boiling water are hot pockets of steam that rush to the cooler surface when temperatures reach or exceed 212° F. Meanwhile, the smaller bubbles which adhere to the interior of a pan before boiling starts contain oxygen that leaves solution as the water warms.
These smaller bubbles need a rough surface in order to form. The sides of a pan or tiny suspended dust particles are perfect.
In The Microwave
But we usually use glass containers in the microwave, which tend to be too smooth for oxygen bubbles.
When you lower that fibrous tea bag into the water, however, there’s suddenly somewhere for bubbles to go. The familiar roil ensues as the cup equilibrates to the new conditions.
As a matter of fact, you’d get the same result if you dropped a pebble in.
This only works with water heated in a microwave because that water is heated evenly throughout. In contrast, water heated on a stove warms unevenly from the bottom up, so by the time all of the water is at boiling temperature, it’s already bubbling violently. | <urn:uuid:eabb1fdf-ba2e-441c-b720-fc50a29436c2> | 3.484375 | 349 | Knowledge Article | Science & Tech. | 56.645625 |
3. Same Function Different Variables
Join the Discussion
When we call the same function from multiple places in our code using the function name followed by parentheses, it will run the same statements using the same variables each time. It would be more useful if we could get it to use different variables each time that we run it.
All three ways to define a function provides a way to specify a number of "arguments" that act as placeholders for the variables that the function is to use. Most of your functions will be defined using the third method we considered so we will look primarily at how to add arguments (and other features) to functions defined that way.
a += y;
b -= z;
The arguments are listed between the parentheses. These arguments can then be used anywhere inside the function as if they were variables. When the function is run the values from the variables are loaded into these arguments.
To link the variables that we want to use to these placeholder arguments we need to pass the variable names as parameters in the call to run the function. We do this by placing the variables themselves inside the parentheses when we run the function. We can also place numerical constants or text strings in the parameters if we want to pass values not held in variables.
var b = 10;
var c = 3;
var d = 4;
var e = 2;
1 myfunction(c, d);
2 myfunction(d, e);
3 myfunction(9, 2);
4 myfunction(b, a);
The code above starts by assigning values to the a and b variables that will be updated by our function from earlier. We also define a few additional variables that we will pass as parameters into the function calls.
- 1 has c as the first parameter and d as the second parameter. Wherever the first argument y appears in the function the value stored in c will be substitutes and wherever the second argument z appears in the function the value from d will be substituted. The result of running the function this first time will therefore be to add 3 to a (giving 3) and subtracting 4 from b (giving 6).
- 2 uses d as the first parameter instead of as the second parameter. The value in d therefore replaces y rather than z in the function. The value in e substitutes for z. The result of running the function this time will therefore be to add 4 to a (giving 7) and subtract 2 from b (giving 4).
- 3 here we have numbers as parameters instead of variables. This works just the same. This time y is 9 and so that is what gets added to a (giving 16) and 2 gets subtracted from b (giving 2).
- 4 shows how we can pass the same variables into a function as are already referenced within the function itself. In this case we are passing b and a which currently contain 2 and 16 respectively. When these are substituted into the function in place of y and z, we end up adding 2 to a (giving 18) and then subtracting 16 from b (giving -14).
Note that it is the value that a has at the time that it is passed into the function that gets substituted into the argument and not the value that the original variable has at that point in the processing. It is the values in the parameters that the function uses and not the variables. This is called pass by value. In those languages where you can pass the actual variable into the function instead of just passing its value the method used to do so is called pass by reference. Had we been able to pass the variables into the function by reference rather than by value then the final value in b would have been -16 instead of -14.
This tutorial first appeared on www.felgall.com and is reproduced here with the permission of the author. | <urn:uuid:dd420a90-7e17-4e5d-b387-5b9ba0c2034f> | 4.15625 | 787 | Documentation | Software Dev. | 62.555759 |
Glass Ingredients and Structure
Name: Gabby S.
Hello, I have been
researching the properties of Glass, I am aware
that it is basically formed from SiO2, but in order
to make it cheaper to produce other ingredients are
added. Commonly Sodium Carbonate and limestone.
Once these components are added, how does this
affect the molecular structure, bonds or properties?
The "glass" made from pure silica (SiO2) you refer to is in
fact called "Fused Silica" or "Fused Quartz" It is rather
inconvenient to process, since it melts at around 2000°C
(almost 4000°F). As you have stated, other compounds are
added, primarily Sodium Carbonate and Lime (not "Limestone"
as you stated) in order to reduce its melting point to the
area of 1000°C. (The difference between lime and limestone is
that Lime is CaO, and Limestone is CaCO3). This type of
glass, which is the most common type available, is called
Both Fused Silica and Soda Lime glasses are both amorphous
"glasses" (there, the word "glass" refers to the molecular
structure, which it totally amorphous, just like a liquid).
These materials are in fact called supercooled liquids,
because like normal liquids, they actually flow at room
temperature.... albeit very, very slowly and imperceptably.
Comparing their properties, Soda-Lime glass will block UV
radiation, whereas Fused Silica does not. Fused Silica also
can withstand much higher temperatures than "normal" Soda-
Lime glass, which is why it is used as an envelope for
halogen light bulbs that operate at temperatures high enough
to soften Soda-Lime glass. Otherwise, these two types of
glass are very similar.
Update: June 2012 | <urn:uuid:ebd2efda-aad7-4b5d-8f07-b7e3ea6ce5f1> | 3.6875 | 407 | Q&A Forum | Science & Tech. | 39.440201 |
Rollercoasters and Hills
Name: Jackie F.
How does height of the first hill impact heights of the
other hill on a rollercoaster track?
The first hill needs to be the highest. The gravitational potential energy
stored in the gravitational field surrounding the train is the maximum
amount of available energy for the system. From here on, the roller
coaster is exchanging gravitational potential energy with kinetic energy
and back again. One problem: friction. Some of the energy flows into
thermal energy and becomes unavailable for the motion of the coaster. This
means that successive hills must be lower.
---Nathan A. Unterman
Click here to return to the Physics Archives
Update: June 2012 | <urn:uuid:6b72a210-3c05-44c5-aafe-de5898040afe> | 3.296875 | 151 | Knowledge Article | Science & Tech. | 46.153889 |
There are quite a few genes that are known to be highly conserved in both sequence and function in animals. Among these are the various Hox genes, which are expressed in an ordered pattern along the length of the organism and which define positional information along the anterior-posterior axis; and another is decapentaplegic (dpp) which is one of several conserved genes that define the dorsal-ventral axis. Together, these sets of genes establish the front-back and top-bottom axes of the animal, which in turn establishes bilaterality—this specifically laid out three-dimensional organization is a hallmark of the lineage Bilateria, to which we and 99% of all the other modern animal species belong.
There are some animals that don’t belong to the Bilateria, though: members of the phylum Cnidaria, the jellyfish, hydra, sea anemones, and corals, which are typically radially symmetric. A few cnidarian species exhibit bilateral symmetry, though, and Finnerty et al. (2004) ask a simple question: have those few species secondarily reinvented a mechanism for generating bilateral symmetry (so that this would be an example of convergent evolution), or do they use homologous mechanisms, that is, the combination of Hox genes for A-P patterning and dpp for D-V patterning? The answer is that this is almost certainly an example of homology—the same genes are being used.
What Finnerty et al. did was to search for and stain for Hox and dpp genes in a cnidarian with bilateral symmetry, Nematostella vectensis. Here is their summary diagram:
Nematostella has perfectly good Hox genes that are expressed in a staggered anterior-posterior pattern. It’s not quite as tidy as the vertebrate or athropod pattern—there’s a lot of overlap, as you can see—but it’s good enough to see the canonical Hox arrangement. Dpp and another gene in the same family, GDF5-like also show the typical metazoan asymmetry. That some members of the Cnidaria exhibit precisely the same molecular organization to their body plan suggests that the function for these molecules arose early in the origin of multicellular animals, and that the radially symmetrical cnidarians have secondarily lost them.
The data summarized here suggest that bilateral symmetry evolved before the split between Cnidaria and Bilateria. Both taxa exhibit bilateral symmetry. Both taxa exhibit staggered Hox expression domains along the primary body axis and asymmetric dpp expression along the secondary body axis. Homology is the most parsimonious explanation for the shared possession of these morphological and molecular traits. If we invoke homoplasy as an explanation, we must presume that one or both of these complex axial patterning systems evolved convergently in two independent evolutionary lineages.
Finnerty JR, Pang K, Burton P, Paulson D, Martindale MQ (2004) Origins of bilateral symmetry: Hox and dpp expression in a sea anemone. Science 304:1335-1337. | <urn:uuid:d5a6428d-6336-4234-97a8-da68ac672b00> | 3.515625 | 671 | Academic Writing | Science & Tech. | 24.329202 |
Mission Type: Orbiter
Launch Vehicle: Atlas II-AS rocket (AC-121)
Launch Site: Cape Canaveral Air Station
NASA Center: Goddard Space Flight Center
Spacecraft Mass: 1850 kg at launch
1) CDS (Coronal Diagnostic Spectrometer)
2) CELIAS (Charge, Element, and Isotope Analysis System)
3) COSTEP (Comprehensive Suprathermal and Energetic Particle Analyzer)
4) EIT (Extreme ultraviolet Imaging Telescope)
5) ERNE (Energetic and Relativistic Nuclei and Electron experiment)
6) GOLF (Global Oscillations at Low Frequencies)
7) LASCO (Large Angle and Spectrometric Coronagraph)
8) MDI (Michelson Doppler Imager)
9) SUMER (Solar Ultraviolet Measurements of Emitted Radiation)
10) SWAN (Solar Wind Anisotropies)
11) UVCS (Ultraviolet Coronagraph Spectrometer)
12) VIRGO (Variability of Solar Irradiance and Gravity Oscillations)
Spacecraft Dimensions: Approximately 4.3 x 2.7 x 3.7 m (9.5 m with solar arrays deployed)
Total Cost: One thousand million Euros
ESA's SOHO Fact Sheet, 30 June 2003. http://sohowww.nascom.nasa.gov/about/docs/SOHO_Fact_Sheet.pdf
The European Space Agency (ESA)-sponsored Solar and Heliospheric Observatory (SOHO) carries twelve scientific instruments to study the solar atmosphere, helioseismology and solar wind. Information from the mission allows scientists to learn more about the sun's internal structure and dynamics, the chromosphere, the corona and solar particles.
The SOHO and Cluster missions, part of ESA's Solar Terrestrial Science Programme (STSP), are ESA's contributions to the Inter-Agency Solar Terrestrial Physics (IASTP) program. NASA contributed three instruments on SOHO as well as launch and flight operations support.
About two months after launch, on 14 February 1995, SOHO was placed at a distance of 1.5 million km from Earth at the L1 Libration Point. The spacecraft returned its first image on 19 December 1995 and was fully commissioned for operations by 16 April 1996.
SOHO finished its planned two-year study of the sun's atmosphere, surface, and interior in April 1998. Communications with the spacecraft were interrupted for four months beginning on 24 June 1998, but, after intensive search efforts, controllers managed to regain full control by 16 September.
Barring three instruments, the spacecraft was functional and was declared fully operational once again by mid-October 1998. SOHO's original lifetime was three years (to 1998), but ESA and NASA jointly decided to prolong the mission, enabling the spacecraft to compare the sun's behavior during low dark sunspot activity (1996) to the peak (around 2000).
The team -- and everyday people who just watch the website -- have also discovered dozens of comets, many of which are destroyed by the sun's powerful gravity and energy. One of SOHO's most important discoveries has been locating the origin of the fast solar wind at the corners of honeycomb-shaped magnetic fields surrounding the edges of large bubbling cells located near the sun's poles.
SOHO remains in its halo orbit, circling L1 once every six months. | <urn:uuid:9f48b313-3ef2-447f-ac47-08aff7d5f7d7> | 3.0625 | 730 | Knowledge Article | Science & Tech. | 36.427909 |
I hope you played with your food when you were young. Perhaps you experimented at some point with pushing a drinking straw through Jell-O. If you twisted the straw as you removed it from your food, you could sometimes trap a column of gelatin in the straw.
You then had the choice of either blowing the Jell-O at a sibling or, if your parents were at the table, gently squeezing the gelatin out of the straw onto your plate with your fingers.
Geologists take samples of ancient muck and mire in a way similar to kids playing with Jell-O. We bang pipes down into the soft earth of lakebeds or peat bogs, pull them up, and push out narrow columns of mud inside.
The muck is composed of many, many layers that go back in time.
We geologists call this activity "coring," and although it’s physically tough work, it’s no more complex than jamming straws into Jell-O.
The reason geologists make cores of mud is that low spots on the Earth can record the climate of the Earth’s past.
Evidence geologists get from coring lakebeds and peatbogs has taught us just how frequently regional and global climate changes.
A Scandinavian geologist got the coring and climate story started. His name was Lennart von Post. He lived and worked around 1900, and he was the first geologist to carefully investigate what cores of muck could reveal about past climates.
Of all the places where geologists can core the Earth, our favorite spot is peat bogs. That’s because peat is the first step in the long geologic process of producing coal, and geologists are inordinately fond of all fossil fuels.
So it was quite natural that von Post started coring the ancient remains of plants and mud layers that make up the peat of southern Sweden.
Little fragments of twigs and leaves can be preserved in peat, and if you can identify the species of plant that produced such material you have your first clue about past climate in a region.
Von Post went to work identifying such bits of old plants, but he also had the wit to look at the ancient mire through a microscope. What he discovered was that he could identify ancient pollen in the layers of peat he was cataloging.
Pollen is surprisingly sturdy stuff. It will remain intact for thousands of years, lying in a layer of muck, waiting for a geologist to come along, core it, and identify the plant that produced it.
If you have allergies, you know pollen is blown around on the slightest breeze. That’s the basic fact that makes pollen much better than twigs or leaves for telling us past climate. Pollen reflects all the plants in a whole region.
If you know the identity of the whole range of plants in a region, you know pretty well what the climate must have been like, both in terms of temperature and precipitation. (Think of gardening "zones.")
Once you’ve described the pollen from a core, you can make a carbon-14 date of a twig and assign a specific age to the climate you’ve been able to deduce.
Ancient pollen makes it crystal clear that climate varies again and again over whole regions on the Earth.
Just for example, in northern Europe where von Post first worked, there have been 10 major climate intervals in the last 15,000 years. Each of these shifts was substantial.
The warmest era — when oak forests covered the lowland of Sweden — was what we geologists call "the Optimum," the balmy times of about 6,000 to 8,000 years ago. That era was much warmer than today.
Some of the great shifts in climate were global in scope, some were only regional. And just to give us all nightmares, some of the biggest shifts in temperature occurred in just 20 years or so — well within a human lifetime.
Studying past climates demands strength in the field, patience in the lab, strong eyes for microscope work — and plenty of courage, too.
The simple but brutal fact is that major and minor climate change is woven into the fabric of the Earth.
E. Kirsten Peters is a native of the rural Northwest, but was trained as a geologist at Princeton and Harvard. Questions about science or energy for future Rock Docs can be sent to firstname.lastname@example.org. This column is a service of the College of Sciences at Washington State University. | <urn:uuid:d44bf5c7-f1af-49d9-b2f3-7a71877094bc> | 4 | 943 | Nonfiction Writing | Science & Tech. | 60.322143 |
In this section about 60 extinct bird species are described. The species accounts are extracted from the foreword of "Handbook of the birds of the World part 7", written by Errol Fuller. The accounts contain a picture (a drawing) of how the species is perceived by an artist. The story of the extinction is next, followed by the reference of the corresponpding science article. While reading about the extinct birds two conclusions may be drawn. First is it never save to be a huge flightless bird and secondly birds living on remote Islands are extremely vulnerable. Errol Fuller starts his writing as follows:
The subject of recent extinctions is one that seems, increasingly, to be a part of popular culture. Today the words Great Auk (Pinguinus impennis), moa (Dinornithidae), Thylacine or Tasmanian Wolf (Thylacinus cynocephalus), Quagga (Equus quagga) and, of course, Dodo (Raphus cucullatus) are names with which many people are familiar. Yet, while the subject has always held an intrinsic fascination, it is one that comparatively few have cared to pursue - until recently. Now, the increasing vigour of the conservation movement, combined with the new vogue for popular science, has brought with it a fresh awareness of, and enthusiasm for, the subject.Select a species in the sidebar of this page. | <urn:uuid:304a1b7a-f23b-4971-bc2a-d71e2b62bbdc> | 3.109375 | 293 | Content Listing | Science & Tech. | 38.824125 |
The figure below portrays estimated sizes of the earth's carbon reservoirs, average annual changes in the amount of carbon held in the reservoirs, and recent flows of CO2 between land and ocean reservoirs and the atmosphere. The size of carbon reservoirs are written in white, while natural processes between these reservoirs appear in yellow. Additional carbon introduced into the system by humans appears in red. For example, humans release 9 GtC/y but 3GtC/y are taken up by plants and soil carbon and another 2 GtC/y goes into the ocean. The remaining 4GtC/y goes into the atmosphere, increasing CO2 concentrations.
|Note: Tan colored pool is decreasing in size. Blue colored pools are increasing. Intensity of blue indicates magnitude of stock change. Numbers in red indicate estimated total amount of carbon in reservoir. Numbers in green indicate average annual change in amount of carbon in reservoir.|
Gigatons (Gt) = 109 metric tons.
Sources: Bolin et al. in IPCC, 2000a; Houghton, 1997. | <urn:uuid:f444fd1d-a65c-41fd-9951-225e240b127c> | 3.609375 | 219 | Knowledge Article | Science & Tech. | 46.188216 |
Space Instrument Observes New Characteristics of Solar Flares
Posted on September 08, 2011 at 09:30:40 am
Using SDO's Extreme ultraviolet Variability Experiment, or EVE instrument designed and built at CU-Boulder, scientists have observed that radiation from solar flares sometimes continues for up to five hours beyond the initial minutes of the main phase of a solar flare occurrence. The new data also show that the total energy from this extended phase of the solar flare peak sometimes has more energy than that of the initial event.
Solar flares are intense bursts of radiation coming from the release of magnetic energy associated with sunspots. Flares are our solar system's largest explosive events and are seen as bright areas on the sun. Their energy can reach Earth's atmosphere and affect operations of Earth-orbiting communication and navigation satellites.
-ADVERTISEMENT-"If we can get these new results into space weather prediction models, we should be able to more reliably forecast solar events and their effects on our communication and navigation systems on Earth," said CU-Boulder Senior Research Associate Tom Woods of the Laboratory for Atmospheric and Space Physics, who led the development of EVE. "It will take some time and effort, but it is important."
"Previous observations considered a few seconds or minutes to be the normal part of the flare process," said Lika Guhathakurta, lead program scientist for NASA's Living With a Star Program. "This new data will increase our understanding of flare physics and the consequences in near-Earth space where many scientific and commercial satellites reside."
On Nov. 3, 2010, a solar flare was observed by SDO. If scientists had only measured the effects of the solar flare as it initially happened, the information would have resulted in underestimating the amount of energy shooting into Earth's atmosphere by 70 percent. The new capability with SDO observations will provide a much more accurate estimation of the total energy input into Earth's environment.
"For decades, our standard for flares has been to watch the X-rays as they happen and see when they peak," said Woods, the principal author on a paper appearing in online in the Astrophysical Journal. "That's our definition for when a flare goes off. But we were seeing peaks that didn't correspond to the X-rays."
Over the course of a year, the team used the EVE instrument to record graphs that map out each wavelength of light as it gets stronger, peaks and diminishes over time. EVE records data every 10 seconds, and thus EVE has observed numerous flares. Previous instruments only measured every hour and a half or didn't look at all the wavelengths simultaneously as SDO can.
"We are seeing something that is new and surprising about the physics of solar flares," said CU-Boulder doctoral student and paper co-author Rachel Hock. "When we looked at the observations from our instruments aboard SDO and compared them with our physical models, the results were consistent with each other," said Hoch of the astrophysical and planetary sciences department. "That was good news to us."
Because this previously unrealized extra source of energy from the flare is equally important in its impact on Earth's atmosphere, Woods and his colleagues are now studying how the late phase flares can influence space weather. In addition to impacting communication and navigation systems, strong solar flares can influence satellite drag and the decay of orbital debris.
When the ionosphere of Earth is disturbed by solar flares and coronal mass ejections, the communication between Earth-based instruments and GPS satellites can degrade, said Woods. "If GPS positions on Earth are off by 100 feet or so because of disruption in the ionosphere, it wouldn't be a big deal for someone driving down a highway," he said. "But if a farmer is using GPS to help determine precisely where to plant particular seeds, that GPS signal error could make a big difference."
To complement the EVE graphical data, scientists used images from another SDO instrument called the Advanced Imaging Assembly, or AIA, built by Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, Calif. Analysis of the images showed the main phase flare eruption and the secondary phase as exhibited by coronal loops or magnetic field lines far above the original flare site. These extra loops were longer and became brighter later than the original set and these loops were also physically set apart from those earlier ones.
SDO was launched on Feb. 11, 2010, and is the most advanced spacecraft ever designed to study the sun and its dynamic behavior. The advanced spacecraft provides images with clarity 10 times better than high-definition television and provides more comprehensive science data faster than any solar observing spacecraft in history.
EVE includes three spectrographs -- two built at CU-Boulder's LASP -- to measure the solar extreme ultraviolet radiation. By making measurements every 10 seconds at 10 times the resolution of previous instruments, EVE is providing scientists and space weather forecasters with the information to provide more accurate, real-time warnings of communications and navigation outages. "We can look at data every minute, 24 hours a day, to help us forecast what the sun is doing," said Woods.
LASP has a long history of making solar measurements dating back to the 1940s, even before NASA was formed, said Woods. LASP projects have ranged from designing, building and flying NASA's Solar Mesospheric Explorer Satellite, which measured the sun's effect on ozone production and destruction of ozone in the 1980s, to the Solar Radiation and Climate Experiment, a $100 million NASA satellite designed, built and now being controlled by LASP to measure the effects of solar radiation on Earth's climate.
"We have a great tradition of working with students in all phases of our programs, starting with helping to design the instruments, helping to calibrate and test them as well as helping to operate them," said Woods. "Our primary focus is getting science results, and our students are helping with the data analysis for the EVE experiment." | <urn:uuid:cd34dc4f-a39e-462b-b3c9-99159c5be1c8> | 3.671875 | 1,216 | Truncated | Science & Tech. | 32.74549 |
Above all, climate models must reflect the real-world climate with acceptable accuracy. So, models are first run using known atmospheric conditions and then validated against observed climate. Validation might include, for example, an assessment of the ability of the model to recreate known features of observed climate, and examination of how well extreme events, such as heatwaves, are represented by the model.
Assuming the physics of the validated model to be consistent for all situations, it can be used to simulate weather over the next season or climate in the future, such as might be expected under Global Warming. Also, the model output can be used to drive impact models of things like agriculture, health, forest fires, etc. that directly assess the likely effects of seasonal variability and climate change.
One of the most important scientific developments in recent years is the move from single modelling centres running and using their own model towards a more co-operative approach in which scientists work with outputs from many different centres. This multimodel or ensemble approach is the one taken in the ENSEMBLES project which involves more than 70 research institutions. | <urn:uuid:37757d96-d21a-41fd-9f1b-98b1813976c8> | 3.359375 | 224 | Knowledge Article | Science & Tech. | 23.324539 |
Key indicators of global climate change include sea levels, carbon dioxide concentration, global surface temperatures, Arctic sea ice, and land ice.
The collection of text and short videos describe the satellite Aqau's fifteen-year mission to provide data on climate change and it's effect on the planet.
The Earth is warming and human activity is the primary cause. Climate disruptions put our food and water supply at risk, endanger our health, jeopardize our national security, and threaten other...
A research supported opinion piece describing the differences between weather and climate and their roles in climate change.
Two sets of materials for learning about Antarctica and global climate: 1) Flexhibit - hands-on learning activities, banners, and video podcasts for after-school groups or classes; and 2) NOVA ? a b...
1999–2013 Advanced Technology Environmental and Energy Center | Leave Feedback | <urn:uuid:b6758c94-2529-40cd-8e00-17bf3f2e6fb5> | 3.515625 | 176 | Content Listing | Science & Tech. | 37.406818 |
Displaying 1 - 16 of 16 resources in Forests and Publications:
1. Audubon Magazine
Publication of the National Audubon Society on the web ...
2. Bama Environmental News - BEN
Birmingham, AL, USA
The Bama Environmental News - BEN website contains a weekly environmental newsletter and information about Alabama's environmental community. Archived editions of BEN since August 1998 ...
3. Book: Non Timber Forest Products in the United States
Portland, OR, USA
An interdisciplinary anthology providing a comprehensive overview of U.S. nontimber forest products (e.g., ferns, mushrooms, medicinals, cones). ...
4. Change Magazine
Poetry, art, news articles and opinions about the environment. ...
5. Earth Island Journal
San Francisco, CA, USA
The Earth Island Journal was first published in 1982 as a class project at Stanford University. A quarterly magazine since 1987, EIJ has won significant ...
6. Elements - Online Environmental Magazine
Environmentally focused articles for the general public. In English/French ...
7. Environmental Rights NOW! Campaign Guide
Washington, DC, USA
This is the guide to taking action on some of the most critical problems facing our environment. ...
8. Global Change
Global Change seeks to familiarize the public with the issues associated with climate change and ozone depletion. ...
9. Great Lakes Bulletin
Benzonia, MI, Benzie
One of the nation's best sources of news and commentary on land use policy reform and environmental protection. ...
10. Hypertext Book in Biodiversity and Conservation
An on-line text book describing the origin, nature and value of biological diversity, the threats to its continued existence, and approaches to preserving what is ...
Resources is RFF`s quarterly newsletter containing news of economic research and policy analysis regarding natural resources and the environment. ...
12. Sustainable Minnesota
Sustainable Minnesota provides coverage of energy policy and sustainable energy work with a focus on Minnesota. ...
13. The Living Cosmos Society
Tempe, AZ, USA
A new, interdisciplinary paradigm, embodying the sciences, and prehistory and history, reveals a fundamnetally biological universe that is also stabilized by life. ...
Philadelphia, PA, USA
Threshold is SEAC's student and youth published movement magazine. It presents articles, in depth features, action alerts, and resources for organizing. ...
15. Tidepool: News for the Rain Forest Coast
Rosburg, WA, USA
Tidepool is a daily collection of news stories for the people living in the North American Coastal Temperate Rain Forest bioregion. ...
16. TIN-MEN - The Green Inquirer
The Inquiring Non-Mainstream Environmental News - focused on positive solutions for Health and the Environment. ... | <urn:uuid:a4c9a009-b4bf-4d02-9d98-c139c6596ff3> | 2.796875 | 584 | Content Listing | Science & Tech. | 35.45255 |