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North Atlantic Right Whales, Eubalaena glacialis
Taxonomy Animalia Chordata Mammalia Cetacea Balaenidae Eubalaena glacialis
Description & Behavior
North Atlantic right whales, Eubalaena glacialis (Müller, 1776), aka Northern right whales, black right whales or Biscayan right whales, are similar in shape to bowheads, being large and stocky, but they are slightly smaller. They are generally the larger of the three right whale species, see southern right whales, Eubalaena australis, with females being slightly larger than males. They are blue-black to light brown in color, with white markings, although some albinos and near-albinos have been recorded. The right whales' most noticeable feature is the horny growth of callosities on and around the head (primarily near the blowhole, around the rostrum, above the eyes and on the jaw). Callosities are outgrowths of tough skin, and are often used to identify individual whales, as they are unique to each animal similar to fingerprints in humans. The largest of callosities are located on the front-most portion of the head and is referred to as the "bonnet." Other excrescences are on the upper edge of the lower jaw, behind their blowhole, and above their eyes.
North Atlantic right whales measure between 13.5-18 m, and weigh in the region of 55,000-95,000 kgs. Their baleen is long and narrow, with a maximum length of 3 m and around 400-540 plates per animal.
Right whales are, despite their massive bulk, incredibly active cetaceans, with breaching, lob-tailing and flipper-slapping all relatively common. A particular favorite is 'sailing', where the whale hangs vertically upside-down in the water, 'standing' on its head, with its tail flukes in the air. They communicate through 'moans' and 'burping' noises.
The North Atlantic right whale was classified along with closely-related southern right whales, Eubalaena australis under the genus Eubalaena, which literally means 'right whale', referring to the belief that these were the 'right' whales to kill because they were known to float after dying, making them easy to catch.
World Range & Habitat
Small concentrations of the North Atlantic right whales can be found in the North Pacific (Eubalaena japonica) and the North Atlantic (Eubalaena glacialis). North Atlantic right whales are only found in the Northern Atlantic Ocean from West of Greenland south to Florida and Texas on the western brim and Madeira on the eastern brim.
All species of right whales can be found in polar waters, but in summer they are normally located in temperate and subpolar seas. Right whales often travel in slow moving, small groups of six or less. They have early migrations to the breeding and birthing grounds in the winter months and travel north to the plankton-rich colder feeding waters in the summer. Dives of up to 50 m for 15-20 minutes are common. Calving seems to occur in shallow bays near to the coast, although there is insufficient evidence for this in some areas.
Feeding Behavior (Ecology)
Northern right whales feed by filtering small marine animals out of the water with their baleen plates. The main food is small crustaceans — copepods, krill, and pteropods. They usually feed below the surface, occasionally near the seabed, on concentrations of copepods. Surface feeding has also been observed.
Mating and birthing occurs February to April in the warmer southern waters. Young are born the following spring after a gestation period of a year and measure about 5.5 m at birth. Young nurse for 6-7 months and by weaning have doubled their body size.
Conservation Status & Comments
Watch full video on vimeo.com. Act Right Now! Learn More About North Atlantic Right Whales at Whales.org
Longevity: Unknown. All three species of right whales were the first large cetaceans to be commercially hunted by man, possibly as early as the 10th Century. In the nineteenth century alone, over 100,000 whales were slaughtered, and, although having been granted protection in 1935, it is doubtful that this species will ever recover.
Estimated Current Population: <1,000 animals (North Atlantic population <300 animals). The most endangered 'great' whale, with full species extinction expected by 2200.
North Atlantic right whales, Eubalaena glacialis, are classified as Endangered D on the IUCN Red List of Threatened Species.
North Pacific right whales, Eubalaena japonica, are classified as Endangered D on the IUCN Red List of Threatened Species:
A taxon is Endangered when the best available evidence indicates that it meets any of the criteria A to E for Endangered (see Section V), and it is therefore considered to be facing a very high risk of extinction in the wild.
LEAST CONCERN (LC)
A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category.
References & Further Research
Center for Biological Diversity: North Pacific right whale
Ocean Life Institute (WHOI) - Right Whales
Tinker, S.W. 1988. Whales of the World. Bell Press: Honolulu
Jefferson, T.A., S. Leatherwood, and M.A. Webber, FAO species identification guide, Marine mammals of the world, Rome, FAO. 1993. 320 p. 587 figs.
U.S. Fish & Wildlife Service Endangered Species
Research Eubalaena glacialis » Barcode of Life ~ BioOne ~ Biodiversity Heritage Library ~ CITES ~ Cornell Macaulay Library [audio / video] ~ Encyclopedia of Life (EOL) ~ ESA Online Journals ~ FishBase ~ Florida Museum of Natural History Ichthyology Department ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList (Threatened Status) ~ Marine Species Identification Portal ~ NCBI (PubMed, GenBank, etc.) ~ Ocean Biogeographic Information System ~ PLOS ~ SCIRIS ~ SIRIS ~ Tree of Life Web Project ~ UNEP-WCMC Species Database ~ WoRMS
Feedback & Citation
Find an error or having trouble with something? Let us know and we'll have a look!
Help us continue to share the wonders of the ocean with the world, raise awareness of marine conservation issues and their solutions, and support marine conservation scientists and students involved in the marine life sciences. Join the MarineBio Conservation Society or make a donation today. We would like to sincerely thank all of our members, donors, and sponsors, we simply could not have achieved what we have without you and we look forward to doing even more. | <urn:uuid:f314e5c3-7f54-4e72-a936-b2f2c178a70d> | 3.796875 | 1,486 | Knowledge Article | Science & Tech. | 43.72346 |
Explore the Entire Region of the Sun’s Influence with NASA's 'Heliophysics Virtual Observatories'
Have you ever wondered how much data exist about the sun and how it affects the solar system and beyond? Data sets and images returned from NASA's cadre of space physics spacecraft, known collectively as the Heliophysics Great Observatory, now can be accessed through one convenient location at the Heliophysics Data Environment (HPDE) web site.
NASA's heliophysics "virtual observatories" are the gateways for its myriad research-quality numerical data, graphs, and awe-inspiring images and movies of the sun, Earth's dazzling, dancing lights, called aurora, and the vast regions of charged particles and magnetic fields within the region of the sun’s influence, called the heliosphere.
Inspired by a desire to make finding space physics information as easy as book lovers locate a text on Amazon.com, the heliophysics virtual observatories offer a wealth of resources to learn more about the sun, Earth and heliosphere. The data are held all around the world, and the virtual observatories make accessing it easy. Armchair astronomers and space-weather aficionados alike will all find something to spark their interest in this vast well of information.
"The virtual observatories are the heliophysics gateway to the data products and resources of NASA's Heliophysics Great Observatory," said Aaron Roberts, project scientist for the Heliophysics Data and Model Consortium at NASA’s Goddard Space Flight Center in Greenbelt, Md. "We still have a fair amount of work to do to fully achieve our goals, but we have come a long way toward easy access to all the data in our domain," adds Roberts.
Multi-instrument and multi-mission studies of the sun and its effects on Earth, the other planets in our solar system, and the heliosphere provide a means to tackle the science problems facing the space physics research community today. Here are just a few of those questions: Why is the solar corona so hot? What would happen if there were a prolonged period of inactivity on the sun? When will a powerful solar flare or coronal mass ejection interfere with navigation and communication systems on Earth?
Citizen astronomers can help researchers in their quest to answer these challenging questions. The first step is becoming informed, and the virtual observatories are a great place to start.
NASA’s Heliophysics Great Observatory's virtual observatories can be accessed from the HPDE web site. Here, you'll find all the resources you need to learn fascinating facts about the sun and its influences on Earth and the heliopshere. Here you can explore the virtual observatories and their resources. For example, click on the "Virtual Space Physics Observatory" and you'll find resources for most of NASA’s heliophysics missions, listed alphabetically by mission, instrument and data set, and searchable by categories such as type of measurement or observatory, or by keywords, using a Google-like search. Other Heliophysics resources will be added to complete the set.
Increasingly, students and others with an interest in how the sun affects Earth through space weather also find these enigmas fascinating. And for those who just want to see pretty images of the sun, they’re there in abundance.
The Heliophysics Great Observatory's space-weather page--another link from the HPDE website--gathers informative resources for students, citizen astronomers, and space-weather buffs. Here you'll find links to current space-weather forecasts and the latest detections of coronal mass ejections—violent outbursts that spew tons of high-speed particles and plasma into the solar wind, sometimes toward Earth. The result can mean interrupted radio signals and global positioning system (GPS) navigation data.
NASA's Heliophysics virtual observatories offer a multitude of resources to learn more about the fascinating life of our nearest star and its effects on Earth and the region influenced by the sun.
For more information about the virtual observatories and the data and resources available through the Heliophysics Great Observatory, visit: > Heliophysics Data Environment
NASA’s Goddard Space Flight Center | <urn:uuid:e71e5906-9168-452a-aaa8-8a6aad465cbf> | 3.40625 | 887 | Knowledge Article | Science & Tech. | 28.709515 |
Michael Goldfarb of Vanderbilt University has established that steam power is the most efficient way to power humanoid robots, with the steam being generated by the palladium-catalysed decomposition of hydrogen peroxide (27 April, p 19). This avoids heavy batteries or the complexities of an internal combustion engine. The only noise comes from the occasional hiss as spent steam is expelled.
So now we know why Marvin, the paranoid android in the
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content. | <urn:uuid:a760aa44-6d1f-4197-86bd-9abc73410637> | 3.140625 | 115 | Truncated | Science & Tech. | 35.511174 |
A UNIQUE community of bacteria living 300 metres beneath the floor of the Pacific Ocean has been investigated for the first time. This is the most detailed study so far of life within the oceanic crust, and it hints at a massive and virtually unknown ecosystem that runs independently of the Sun's energy.
Almost every microbe found there belongs to a completely new species. "It's a very exotic group of organisms," says Stephen Giovannoni at Oregon State University.
Giovannoni's team took their samples from a borehole off the coast of Oregon, near the centre of the Juan de Fuca ridge. The hole passes through 250 metres of sediments and 50 metres of basaltic crust, and was originally drilled in 1996 to yield geological data. But it was also a unique opportunity to find out more about microbes living in the crust.
Fluid at the bottom of the borehole is under ...
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content. | <urn:uuid:cc72a504-fd8e-4d89-b4e4-0e02d88f7176> | 3.84375 | 213 | Truncated | Science & Tech. | 48.430985 |
Do you think the pollution will still be on Earth in 100 years?
Yes, (and some people will still be around on Earth in 100 years
too: my Grandmother is 90 years old and still going strong!) Some kinds of
pollution are a necessary part of life, and will be around as long as there
are living things. Other kinds of pollution happen as a result of human
industry - the things we make for a more comfortable life sometimes generate
toxic waste that is harmful to life if it is not destroyed or stored safely.
For the first 100 years of the Industrial Revolution, people did not always
handle the waste safely, because there was plenty of room to just "throw it
away" so it would not bother anyone. More recently we have begun to recognize
the health problems caused by some kinds of pollution and are more careful
about how wastes are handled and disposed of. There is a special kind of waste
that is radioactive and harmful to life, but which does not break down and
become harmless for a very long time (up to 10,000 years in some cases). This
nuclear waste must be kept isolated from the environment in a special kind of
dump, and scientists here at Argonne are working hard to find better ways to
keep radioactive waste from bothering people.
Click here to return to the Environmental Science
Update: June 2012 | <urn:uuid:8105253b-ed1d-4758-9c70-07f67c0f3f5c> | 3.15625 | 285 | Knowledge Article | Science & Tech. | 45.895139 |
Endocarpon pusillum is an unusual lichen, because the algal component is not only found in the vegetative body, but also in the spore-forming fruiting body. This means it can be dispersed along with the fungal partner.
The lichen species Endocarpon pusillum grows on soils and forms squamules up to about 4mm. © C Gueidan
This characteristic probably helps the lichen colonise otherwise bare substrates.
The species often grows in areas where land is grazed by farm animals. As agricultural practices have changed, however, the lichen has become less common and may even be extinct in the UK.
Find out how to recognise Endocarpon pusillum.
Endocarpon pusillum is found worldwide, in arid and cool to temperate regions. It colonises bare soils and contributes to soil conservation. Find out more.
A lichen is two distinct organisms - a fungus and an alga - living symbiotically. Find out where the algae live and how this long-term partnership benefits both species.
Changes in farming practices have led to the decline of Endocarpon pusillum. Find out why.
Get more information on Endocarpon pusillum.
A typical landscape habitat for Endocarpon pusillum.© A Wolff - CEEP
Biotic soil crust formed of Endocarpon pusillum, cyanobacteria (Nostoc) and mosses.© C Gueidan
Squamule of Endocarpon pusillum with several fruiting bodies.© C Gueidan
Lichen Researcher, Botany Department.
"This species seems to have become rare in the UK, most probably because of habitat loss. Historically, Endocarpon pusillum has been used in many experiments on lichen development. Conservation measures are necessary to protect this biologically-interesting lichen species."
Plural of ascus - sexual spore-bearing cells.
Regular, brick wall-like arrangement.
Bottle-shaped fruiting body.
Hairlike growths that bind the thallus to its substrate.
A small, loosely attached thallus lobe - vegetative structure.
Close and long-term interaction between two different species. | <urn:uuid:80d061ea-9f00-49e8-a11f-9aa57e572f78> | 4.03125 | 479 | Knowledge Article | Science & Tech. | 31.816504 |
|Jan29-12, 05:50 PM||#1|
Simple Diode Analysis Problem - Calculating Current/Voltage in a diode:
1. The problem statement, all variables and given/known data
Refer to the figure attached. Let IS = 25 fA and VCC = 10V. What is the total current, the current in the diode, and the current in the 5KΩ resistor? What is VD? Use the iteration technique.
2. Relevant equations
Ideal Diode Equation: I = Is(e^(Vd/Vt) - 1)
Ohm's Law: V= IR
Thermal Voltage: V = kt/q = 25.9mV
3. The attempt at a solution
Total Current in the circuit = 10 V / 10kΩ = 1mA
We need to find the Vd and Id using the constant voltage model and then use the iteration method using the ideal diode equation to get closer and closer to Vd and Id using iterations.
I am not sure how to analyze the circuit using the constant diode equation. I know how to use the iteration method.
Current through the diode = Current through the 5kΩ resistor.
Please help - Any suggestions will be helpful.
|Jan30-12, 08:31 AM||#2|
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|Another problem, voltage characteristic in a diode circuit||Electrical Engineering||3| | <urn:uuid:a154e3a2-b6c4-451a-b0e3-6fbff92c5517> | 2.8125 | 438 | Comment Section | Science & Tech. | 59.091581 |
For starters, the bird had small feathers on its hind legs. When he began doing a feather-by-feather reconstruction of its wings, working from a fossil in Germany, he found it didn’t look like a modern bird at all. Instead of the single layer of feathers that give modern birds their dextrous flight abilities, the fossil appeared to have layers of feathers stacked on top of each other, almost like two-ply tissues.
“I realized you couldn’t really get from what the fossils showed to the way people were drawing it,” Longrich said. “People have been drawing the wing this one way for more than 100 years, and had this particular idea about what the wing would look like. And this is coming along after more than a century and saying we got it wrong.”
His painstaking study of the Archaeopteryx fossil suggested to Longrich that this Jurassic-era bird had a primitive wing, and may not have been very good at flying. But instead of publishing his observation, he decided to sit on it. He wasn’t sure that his colleagues would be convinced; it might have been something strange about the way the specimen he was studying was fossilized.
A few years later, a scientist working down the hall from him, Jakob Vinther, began studying a fossil of a feathered dinosaur that had been recently discovered in China, called Anchiornis huxleyi. Vinther was not a bird specialist—in fact, Longrich said, Vinther normally studied fossils of ancient squid, octopi, and worms. But that also meant Vinther didn’t have the same preconceptions, and when he looked at the fossil he also saw wings with multiple layers of feathers. | <urn:uuid:34dd02ee-0d38-45a2-8440-b120871f5140> | 3.5625 | 363 | Nonfiction Writing | Science & Tech. | 55.549507 |
The Science Guys
Science Guys > August 2002
I have heard a light bulb has glass around it to keep air away from the filament. Can a light bulb burn in space where there is no air without glass around it?
We may have all heard of interesting things happening in space where there is a weightless environment (not gravity free) or where there is no air. For example, what is the shape of a candle flame burning in a chamber of air on a spacecraft? It is not tapered as it is here on Earth. Thus phenomena that we experience here on Earth act differently under the weightless conditions found in "space."
The typical incandescent light bulb contains a thin wire (usually tungsten) called a filament that has a high electrical resistance. This filament gets very hot when an electric current passes through it. The intense temperature makes the filament glow brightly. If oxygen were present the glowing hot filament would burn up. For combustion as we know it, oxygen must be present. In order to keep oxygen away from a light bulb’s filament on Earth, some bulbs have most of the air removed, others are simply filled with an inert gas (one that does not burn or aid combustion). Thus on Earth the glass globe around the filament is necessary to keep the filament isolated from the oxygen in the air. (It also protects us from the exposed wires and hot filament.)
Since there is no air (oxygen) in outer space, a filament without a glass covering would simply glow and not be consumed by traditional burning.
Actually, the filament gets so hot it literally boils off atoms and electrons. Sometimes this material collects as a dark spot at the top of the bulb. Eventually the filament deteriorates, becomes weak, and breaks, thus ending the life of the light bulb. In some cases the presence of a gas can actually inhibit the filament’s deterioration to a certain degree. With a gas present the filament’s atoms cannot boil off as readily, so the filament’s life is prolonged. In some bulbs the filament can even burn hotter and thus give off more light if a particular type of gas is present in the bulb. Today, halogen gases are often used in bulbs to improve the quality of light bulbs. These bulbs are currently promoted as giving longer life and more light.
In summary, bulbs on Earth have most of the air removed or are simply filled with an inert gas (one that does not burn or aid combustion) in order to keep oxygen away from a light bulb’s filament. Thus the globe is necessary to keep the filament isolated from the oxygen in the Earth’s atmosphere. In space a bulb could burn for a considerable time without a globe but the emptiness of space could hasten the evaporation of the filament and eventually the filament would break just as it does on Earth. | <urn:uuid:dc104064-3d91-4b22-8208-a415f8091fc4> | 3.4375 | 580 | Knowledge Article | Science & Tech. | 51.829991 |
The purpose of the statements is to tell the browser what to do.
Normally you add a semicolon at the end of each executable statement.
Using semicolons also makes it possible to write many statements on one line.
You might see examples without semicolons.
Each statement is executed by the browser in the sequence they are written.
This example will manipulate two HTML elements:
Blocks start with a left curly bracket, and end with a right curly bracket.
The purpose of a block is to make the sequence of statements execute together.
This example will run a function that will manipulate two HTML elements:
You will learn more about functions in later chapters.
A function getElementById is not the same as getElementbyID.
A variable named myVariable is not the same as MyVariable.
You can break up a code line within a text string with a backslash. The example below will be displayed properly:
However, you cannot break up a code line like this:
The perfect solution for professionals who need to balance work, family, and career building.
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The CSS Certificate documents your knowledge of advanced CSS.
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The ASP Certificate documents your knowledge of ASP, SQL, and ADO.
The PHP Certificate documents your knowledge of PHP and SQL (MySQL).
Your message has been sent to W3Schools. | <urn:uuid:59bc354d-b663-4cc4-86bc-be2a22b7bd4a> | 3.75 | 339 | Documentation | Software Dev. | 48.634813 |
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2000 June 9
Explanation: This stunning image from the orbiting Chandra X-ray Observatory is centered on the Vela pulsar -- the collapsed stellar core within the Vela supernova remnant some 800 light-years distant. The Vela pulsar is a neutron star. More massive than the Sun, it has the density of an atomic nucleus. About 12 miles in diameter it spins 10 times a second as it hurtles through the supernova debris cloud. The pulsar's electric and magnetic fields accelerate particles to nearly the speed of light, powering the compact x-ray emission nebula revealed in the Chandra picture. The cosmic crossbow shape is over 0.2 light-years across, composed of an arrow-like jet emanating from the polar region of the neutron star and bow-like inner and outer arcs believed to be the edges of tilted rings of x-ray emitting high energy particles. Impressively, the swept back compact nebula indicates the neutron star is moving up and to the right in this picture, exactly along the direction of the x-ray jet. The Vela pulsar (and associated supernova remnant) was created by a massive star which exploded over 10,000 years ago. Its awesome x-ray rings and jet are reminiscent of another well-known pulsar powered system, the Crab Nebula.
Authors & editors:
Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/GSFC
& Michigan Tech. U. | <urn:uuid:cf780806-308a-46f5-bb2c-70a0de347c12> | 3.59375 | 344 | Knowledge Article | Science & Tech. | 47.671809 |
A function is continuous at a point if
that is, for every arbitrarily small positive constant there exists () such that
for all and that satisfy .
A function is continuous on a point set if it is continuous at all points of . A function is piecewise continuous on , where and are intervals, if it is piecewise continuous in for each and piecewise continuous in for each .
The function is continuously differentiable if , , and are continuous, and twice-continuously differentiable if also , , , and are continuous. In the latter event
If is continuously differentiable, , and at , then in a neighborhood of , that is, an open disk centered at , the equation defines a continuously differentiable function such that , , and .
The notations given in this subsection, and also in other coordinate systems in the DLMF, are those generally used by physicists. For mathematicians the symbols and now are usually interchanged.
With , ,
The Laplacian is given by
If is times continuously differentiable, then
where and its partial derivatives on the right-hand side are evaluated at , and as .
has a local minimum (maximum) at if
and the second-order term in (1.5.18) is positive definite (negative definite), that is,
Sufficient conditions for validity are: (a) and are continuous on a rectangle , ; (b) when both and are continuously differentiable and lie in .
Suppose that are finite, is finite or , and , are continuous on the partly-closed rectangle or infinite strip . Suppose also that converges and converges uniformly on , that is, given any positive number , however small, we can find a number that is independent of and is such that
for all and all . Then
Let be defined on a closed rectangle . For
let denote any point in the rectangle , , . Then the double integral of over is defined by
as . Sufficient conditions for the limit to exist are that is continuous, or piecewise continuous, on .
For defined on a point set contained in a rectangle , let
provided the latter integral exists.
If is continuous, and is the set
with and continuous, then
where the right-hand side is interpreted as the repeated integral
In particular, and can be constants.
Similarly, if is the set
with and continuous, then
Infinite double integrals occur when becomes infinite at points in or when is unbounded. In the cases (1.5.30) and (1.5.33) they are defined by taking limits in the repeated integrals (1.5.32) and (1.5.34) in an analogous manner to (1.4.22)–(1.4.23).
Moreover, if are finite or infinite constants and is piecewise continuous on the set , then
whenever both repeated integrals exist and at least one is absolutely convergent.
Finite and infinite integrals can be defined in a similar way. Often the sets are of the form
where is the image of under a mapping which is one-to-one except perhaps for a set of points of area zero.
Again the mapping is one-to-one except perhaps for a set of points of volume zero. | <urn:uuid:52f87b3c-4ba6-4bf8-af40-136354b057ef> | 2.875 | 679 | Knowledge Article | Science & Tech. | 48.868461 |
Balaenoptera bonaerensis occurs in polar to tropical waters of the southern hemisphere. It occurs in large numbers south of 60º S, throughout the Antarctic. The distribution is more difficult to assess north of the Antarctic because of its co-occurrence with Balaenoptera acutorostrata. As a result, the boundaries of the species’ winter distributions remain largely undefined. Balaenoptera bonaerensis is observed off the coast of Brazil and South Africa and there have been occasional sightings in Peru. An unknown proportion of the species remains in Antarctic waters during the winter.
Biogeographic Regions: antarctica (Native ); indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
- Mead, J., R. Brownell Jr. 2005. Order Cetacea. Pp. 2142 in D Wilson, D Reeder, eds. Mammal Species of the World. A Taxonomic and Geographic Reference (3rd Ed.). Baltimore: John Hopkins University Press.
No one has provided updates yet. | <urn:uuid:b3ab2120-7ee2-40ff-96df-a81caed41195> | 3.625 | 223 | Knowledge Article | Science & Tech. | 36.884167 |
There is one instance for each circle-year.
These two fields are the composite key used to relate a circle-year to a circle.
The year number as a string of three digits with
left zero fill, e.g., “
008”. See Section 3.3, “Year number”.
The year key for this circle-year, left-justified and
blank-filled to length 5. S see the discussion of the
year_key attribute in Section 4.1.7, “Attributes of the
efforts table”. Example values (where
_ represents a space):
0001_ 0027_ 0027b NMZU_
Date as a
Number of observers as an
All these hour- and mile-based quantities use
decimal.Decimal type, with
a precision of one digit after the decimal point.
Note that quantities in this type can be formatted
using a “
as in this conversational example.
>>> d1=decimal.Decimal('1.4') >>> d2=decimal.Decimal('3.47') >>> d3=d1+d2 >>> d3 Decimal('4.87') >>> "%6.1f" % d3 ' 4.9' >>> "%6.3f" % d3 ' 4.870'
Circle instance for to this
An iterator that produces all the
Census instances for this circle-year. | <urn:uuid:6377f76f-7961-4c43-8d98-01904c83aa73> | 2.71875 | 312 | Documentation | Software Dev. | 83.944121 |
A working knowledge of surface tension allows you to shove a skewer through a balloon without popping it and a pencil through a plastic bag full of water without spilling. Make your nieces and nephews think you're cool.
Surface tension occurs when a group of molecules are more attached to each other than they are to the molecules around them. This can be because they are a series of interwoven polymers, like plastic, or because they are polarized atoms attracted to each other, like water.
The point is, they feel a force that pulls them together. Balloons are basically a layer of rubber trying to pull itself back into shape against the outward pressure of the air trapped inside it. It's that constant pull back towards itself that allows you to stick a pin, or a knitting needle, through a balloon without popping it.
The important thing is to not stick the pin in fast. For beginners, it's also important not to stick it through the sides of the balloon. At the sides, the balloon's material is often already stretched to capacity and the sharp motion won't give the rubber time to squeeze around the pin. Instead, insert the pin at the tied-off end of the balloon and let it come out at the slightly denser rubber at the tip. Do it slowly and carefully, making sure it doesn't overs-tretch the material around it. As the pin pushes in, it distorts the rubber. If it lets air leak through, forcing the rubber farther apart in a tear, the balloon bursts.
Once the pin is in, the balloon should deflate. The air is straining at the sides of the balloon, but it needs a hole to open in order to get out. The pull of strings of polymer in the balloon is great enough that even though the pin breaches the skin of the balloon, the material around the pin squeezes around the intruder so tightly that the air can't shove its way out. The balloon reseals.
The same thing happens with plastic bags filled with water. If a pencil, or other smooth, regular object is inserted into the bag, the plastic will squeeze tight enough around the object that it can resist the pressure from water within.
You can see surface tension working in water droplets. Water droplets don't have an obvious skin, but they are held together by a membrane of surface tension. Individual drops on horizontal surfaces build up over time, getting taller and fatter, until they look like balloons. A fast touch will make them collapse, while a thin, slow-moving object inserted into the drop won't splatter it, letting it keep its bead-like appearance. | <urn:uuid:a4035fad-487a-4647-b676-82bdf6e1d16b> | 4.03125 | 539 | Tutorial | Science & Tech. | 60.29692 |
The Aeronomy of Ice in the Mesosphere (AIM) experiment studies Polar Mesospheric Clouds (PMC's), the ice crystal clouds that form in the Earth’s mesosphere. AIM helps uncover why these clouds form and why they vary, quantifying the connection between PMC's and the meteorology of the polar mesosphere. The AIM mission seeks to create a foundation for the study of long-term change in the mesosphere and its relationship to global change.
The overall goal of the Aeronomy of Ice in the Mesosphere (AIM) experiment is to resolve why PMC's form and why they vary. By measuring PMC's and the thermal, chemical and dynamical environment in which they form, researchers will quantify the connection between these clouds and the meteorology of the polar mesosphere. In the end, this will provide the basis for study of a long-term variability in the mesospheric climate and its relationship to global change. The results of AIM will be a rigorous validation of predictive models that can reliably use past PMC changes and present trends as indicators of global change. This goal will be achieved by measuring PMC abundances, spatial distribution, particle size distributions, gravity wave activity, dust influx to the atmosphere and precise, vertical profile measurements of temperature H2O, OH, CH4, O3, CO2, NO, and aerosols. These data can only be obtained by a complement of instruments on an orbiting spacecraft.
Over the last 30 years ground based observations from NW Europe of the number of noctilucent clouds (NLC's) show dramatic increases. These clouds, known more recently to satellite observers as PMC's, are believed to respond dramatically to even small changes in their environment. Since cooling of the upper atmosphere (PMC's occur near 85 km) is expected to accompany the possible warming of the lower atmosphere due to an increased greenhouse effect, an increase in mesospheric cloudiness could be one consequence of mesospheric climate change. | <urn:uuid:00e78ba1-ee09-42c5-8b1e-466ef3eab407> | 3.03125 | 411 | Knowledge Article | Science & Tech. | 31.073606 |
pathconf, fpathconf - get configurable pathname variables
pathconf(const char *path, int name);
fpathconf(int fd, int name);
The pathconf() and fpathconf() functions provides a method
to determine the current value of a configurable system limit or
option variable associated with a pathname or file descriptor.
For pathconf, the path argument is the name of a file or directory. For
fpathconf, the fd argument is an open file descriptor. The
specifies the system variable to be queried. Symbolic constants for each
name value are found in the include file <unistd.h>.
The available values are as follows:
The maximum file link count.
The maximum number of bytes in a terminal canonical
The maximum number of bytes for which space is
available in a
terminal input queue.
The maximum number of bytes in a file name.
The maximum number of bytes in a pathname.
The maximum number of bytes which will be written
atomically to a
Return 1 if appropriate privileges are required for
system call, otherwise 0.
Return 1 if file names longer than KERN_NAME_MAX are
Returns the terminal character disabling value.
If the call to pathconf or fpathconf is not successful, -1
and errno is set appropriately. Otherwise, if the variable
with functionality that does not have a limit in the system,
-1 is returned
and errno is not modified. Otherwise, the current
If any of the following conditions occur, the pathconf and
functions shall return -1 and set errno to the corresponding
[EINVAL] The value of the name argument is invalid.
[EINVAL] The implementation does not support an association of the
variable name with the associated file.
pathconf() will fail if:
[ENOTDIR] A component of the path prefix is not a directory.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an
entire path name exceeded 1023 characters.
[ENOENT] The named file does not exist.
[EACCES] Search permission is denied for a component
of the path
[ELOOP] Too many symbolic links were encountered in
[EIO] An I/O error occurred while reading from or
the file system.
fpathconf() will fail if:
[EBADF] fd is not a valid open file descriptor.
[EIO] An I/O error occurred while reading from or writing to the file
The pathconf and fpathconf functions first appeared in
OpenBSD 3.6 June 4, 1993
[ Back ] | <urn:uuid:9e1b9a1c-c627-4c27-8579-0c0c7c5eb3cc> | 2.890625 | 576 | Documentation | Software Dev. | 43.149959 |
Robert Lichter reports on a survey of American climate scientists commissioned by STATS at GMU. Some of the findings:
In 1991 the Gallup organization conducted a telephone survey on global climate change among 400 scientists drawn from membership lists of the American Meteorological Association and the American Geophysical Union.
We repeated several of their questions verbatim, in order to measure changes in scientific opinion over time. On a variety of questions, opinion has consistently shifted toward increased belief in and concern about global warming. Among the changes:
In 1991 only 60% of climate scientists believed that average global temperatures were up, compared to 97% today.
In 1991 only a minority (41%) of climate scientists agreed that then-current scientific evidence “substantiates the occurrence of human-induced warming,” compared to three out of four (74%) today.
Scientists find Al Gore much more reliable than the media:
Only 1% of climate scientists rate either broadcast or cable television news about climate change as “very reliable.” Another 31% say broadcast news is “somewhat reliable,” compared to 25% for cable news. (The remainder rate TV news as “not very” or “not at all” reliable.) Local newspapers are rated as very reliable by 3% and somewhat reliable by 33% of scientists. Even the national press (New York Times, Wall St. Journal etc) is rated as very reliable by only 11%, although another 56% say it is at least somewhat reliable.
Former Vice President Al Gore’s documentary film “An Inconvenient Truth” rates better than any traditional news source, with 26% finding it “very reliable” and 38% as somewhat reliable. Other non-traditional information sources fare poorly: No more than 1% of climate experts rate the doomsday movie “The Day After Tomorrow” or Michael Crichton’s novel “State of Fear” as very reliable. | <urn:uuid:1457585f-715d-434f-847e-e26558a61edf> | 2.90625 | 407 | Knowledge Article | Science & Tech. | 33.763106 |
The Araneae are the true spiders. Unlike the fossil spider-like trigonotarbids and their allies, almost all spiders have only five segments in the abdomen, and these are generally fused with no external trace of segmentation -- the earliest spiders had as many as twelve segments in their abdomen.
The last two abdominal segments are specially modified into spinnerets which secrete the silk threads for which spiders have become well known. There are one to four pairs of spinnerets present, even on those spiders which do not spin webs. The silk has many other functions, such as in sperm transfer, encasing the eggs, and building nests or burrows. Those spiders which do use their silk for webs often produce complex and intricate patterns, but complex or not, the web's function is the capture of prey.
Other spiders which do not spin webs will stalk or ambush their prey. Wolf spiders, tarantulas, and jumping spiders are of this sort. Some species are brightly colored, and hide within flowers where they are camouflaged, waiting to pounce on visiting insects. A very few of these are large enough to capture small birds. These spiders rely on their amazing speed and paralyzing poison to subdue their captures.
The front pair of appendages, the chelicerae, are the ones which contain the poison glands. The second pair, the pedipalps, are small, and are used by the male during mating. The head bears four pairs of eyes, the arrangement of which can be very useful for the identification of the several different kinds of spider. Most spiders breathe through tracheae; some, like the wolf spiders, have both book lungs and tracheae.
As with other arachnids, there is an abundance of fossils in the mid-Paleozoic and the later part of the Cenozoic. However, there are no known spiders from the Mesozoic, a gap in the record of 200 million years.
For more on the phylogeny of spiders, visit the Araneae pages at the Tree of Life, maintained at the University of Arizona.
Spider photographs are available from the Arachnid Mailing List -- also with links to other spider pages. Also check out the guide to the jumping spiders (Salticidae) of America north of Mexico for information on one of the larger families of spiders.
Petrunkevitch, A. 1960. Arachnida. P42-P162 in Moore, R.C. (ed.) Treatise on Invertebrate Paleontology. Part P: Arthropoda 2: Chelicerata. Geological Society of America and University of Kansas Press, Lawrence, Kansas. | <urn:uuid:b857886e-19d4-489c-b703-b3bb03af138d> | 3.765625 | 555 | Knowledge Article | Science & Tech. | 48.125627 |
'Light Dusting' Of Ash As Alaska Volcano Erupts
Alaska's Mount Redoubt volcano has erupted four times since Sunday night, sending an ash plume more than 9 miles high into the air — but Anchorage, the state's largest city, has likely been spared from any ashfall.
"The ash cloud went to 50,000 feet, and it's currently drifting toward the north, northeast," said Janet Schaefer, a geologist with the Alaska Volcano Observatory.
The first eruption occurred at 10:38 p.m. Sunday night, and the fourth happened at 1:39 a.m. Monday, according to the observatory.
The current wind patterns are taking the ash cloud away from Anchorage and toward Willow and Talkeetna, two communities near Mount McKinley — North America's largest mountain — in Denali National Park.
Geophysicist John Power said no cities have yet reported any ash fall from the volcano, but he noted that it's still early.
Using radar and satellite technology, the National Weather Service predicted that ash would start falling later Monday morning.
Article continues: http://www.npr.org/templates/story/story.php?storyId=102231154 | <urn:uuid:a16641dc-aa08-4d9d-b166-43f2d4452dce> | 2.875 | 253 | Truncated | Science & Tech. | 58.372967 |
The sun is a very active place. The circular feature shooting out from the sun is an eruption. The little picture of Earth has been placed next to this eruption to show how big these eruptions are. (Earth is not really that close to the sun!) The sun is bright orange in this view. It was taken in the extreme ultraviolet, a wavelength of light that our eyes cannot see but spacecraft instruments can. Scientists use this view to reveal activity at the sun that would otherwise go unnoticed. One thing learned from ultraviolet views is how large the sun's eruptions are.
NASA's Solar Dynamics Observatory took this image.
Image credit: NASA/GSFC | <urn:uuid:930cb279-4ff6-4a4c-a9f6-93fcc86437a8> | 3.84375 | 133 | Knowledge Article | Science & Tech. | 57.769903 |
You may recall a scene from "Star Wars" where Luke Skywalker looks out across the landscape of a planet called Tatooine, which had two suns. This year, amateur scientists discovered that in reality, there is a planet with not just two, but four, suns.
This planet, called PH1, is special for another reason: It's the first confirmed planet that the Planet Hunters group has identified. Planet Hunters is a citizen science organization, made of people just like you, who are combing through planet data. The group has also helped identify several planet candidates. Learn more at planethunters.org.
6. Nearby star has a planet
The closest planet we know of to Earth, outside of our solar system, was identified in October. This planet orbits a star called Alpha Centauri B. It's unlikely to harbor life, but there's hope that other potential planets in that area might be more hospitable to breathing creatures.
Of course, when we say "close," we mean 4 light-years, or 23.5 trillion miles, away.
About 800 planets have been confirmed to exist outside our solar system, in addition to nearly 2,000 planet candidates found with the Kepler mission.
7. Vesta becomes a 'protoplanet'
NASA's Dawn spacecraft helped scientists to determine that Vesta, originally thought of as an asteroid, is a "protoplanet." That means that its structure has a dense, layered body, and it orbits the sun.
What's the difference between a protoplanet and a planet? It appears that something interrupted the development of protoplanets, which aren't fully formed, so they don't quite make the cut as full-fledged planets.
8. Bye-bye, space shuttles
In 2011, we said goodbye to NASA's Space Shuttle Program. This year, we saw the four surviving orbiters making Earthly journeys -- whether flown or towed -- to new homes at museums and similar attractions.
Discovery is at the Udvar-Hazy Center at the Smithsonian Institution's National Air and Space Museum in Chantilly, Virginia. It flew on the back of a 747 from Kennedy Space Center. This is the most traveled of the space shuttles.
Enterprise is at the Intrepid Sea-Air-Space Museum in New York. This shuttle never actually went into space, but it was carried on a 747 jet from Washington to New York in June. It was originally designed as a prototype test vehicle.
Endeavour is at the California Science Center in Los Angeles, having flown from Kennedy Space Center on the back of a 747. To make room for it to be towed through the city, dozens of trees were cut down and traffic signs removed.
Atlantis is at the Kennedy Space Center in Merritt Island, Florida. It was the last space shuttle to go to space, and the last to come to rest this year. Unlike the other shuttles, which made flyovers in various parts of the United States, Atlantis moved only 10 miles, towed by land to the Kennedy Space Center Visitor Complex in November.
The other two shuttles -- Challenger and Columbia -- did not make it back to Earth after accidents that killed their entire crews.
9. SpaceX gets to the space station, and back
No NASA shuttles flew in 2012, but a private company called SpaceX successfully sent almost 900 pounds of cargo to the international space station in its first official mission in October. The Dragon capsule came back with nearly 1,700 pounds of freight. This was only months after the SpaceX demonstration flight in May.
NASA and SpaceX have a contract for a dozen flights to the space station, and the October trip was just the first.
SpaceX isn't the only player in this commercial spaceflight arena. Virgin Galactic, Sir Richard Branson's private spaceflight company, recently completed a high-altitude test. Orbital Sciences is also under contract with NASA, and will also launch a demonstration flight.
10. Baby's DNA constructed before birth
For the first time, researchers at the University of Washington were able to construct a near-total genome sequence of a fetus, using a blood sample from the mother and saliva from the father.
The study suggested this method could be used to detect thousands of genetic diseases in children while they are still in the fetal stage. In the long run, it could help scientists derive new insights about genetic diseases.
Right now, this sequencing costs in the neighborhood of $50,000, but given how rapidly the price of genetic testing is falling, the process may become less expensive over time. Of course, it also raises ethical issues about selecting certain desirable traits in children. For right now, however, the technology is still in its early stages.
What were your favorite science stories this year? Share them in the comments. | <urn:uuid:896f1c83-39ba-473e-879a-4e207759d2f7> | 3.421875 | 997 | Listicle | Science & Tech. | 54.330324 |
Editor's note: The Science Seat is a feature in which CNN Light Years sits down with movers and shakers from many different areas of scientific exploration. This is the first installment.
Jason Kalirai is the deputy project scientist for the James Webb Space Telescope, which will be NASA's next big mission in astrophysics. He works at the Space Telescope Science Institute in Baltimore.
Last month, Kalirai, 34, won the American Astronomical Society's Newton Lacy Pierce Prize for his achievements in observational astronomy. CNN Light Years recently spoke with him about his work. Below is an edited transcript.
CNN: What inspired you to pursue a degree in science?
Jason Kalirai: As far back as I can remember, I was curious about the way things work. I'm sure I got this trait from my father, whom my friends actually nicknamed "MacGyver" when we were growing up. He enjoyed questioning how things operate and then trying to solve everyday problems through experimentation.
When I was in elementary school, I was fascinated by the night sky, and I wanted to understand the scale of the universe -- how big it was, how separated the stars were, what else was out there? I started reading books about the Milky Way galaxy and the universe, put posters of our solar neighborhood in my room and kept asking the question "why." Science not only provided me with the answers to these grand questions, but it opened up new mysteries that I was motivated to learn about.
CNN: What are five steps through which an astronomer solves a problem?
Kalirai: Astronomical research has many components to it. Astronomers are well-rounded and excel at problem-solving, data acquisition and analysis, writing reports and presenting results. Solving a single problem can take many years through this cycle:
In the first step of the process, astronomers design an experiment to solve a particular problem that they are interested in. Usually, this involves writing a proposal to use a telescope to gain new insights on the universe.
Next, astronomers obtain the observations. For ground-based astronomy, this typically means traveling to a mountaintop and collecting data, whereas for space-based observations the data are sent directly to the astronomer.
Scientists then analyze the observations using powerful computers, usually in their own offices. They also spend time writing computer programs to aid in the analysis. New discoveries are rare, so it takes very careful attention to details in the data.
Astronomers publish (their) results in peer-reviewed journals, so they have to write detailed reports of all of their findings. These reports are judged by other astronomers to make sure they are based on sound principles.
Finally, astronomers present their findings to the science community through domestic and international meetings.
CNN: What kind of astronomer do you consider yourself?
Kalirai: My focus is on observational astronomy, and I'm particularly passionate about using telescopes to push beyond the limits of what we've already seen. I try to discover new population of stars in our Milky Way galaxy and try to reveal new parts of galaxies in the nearby universe. Whenever I can get access to a new capability or technology in astronomy (e.g., a more sensitive camera), I like to take that tool and apply it to the kind of science problems that I most enjoy working on.
CNN: Why do you focus on star clusters?
Kalirai: Star clusters are one of the universe's most remarkable environments. In a small region of space that is not too much larger than the distance between the sun and the nearest few stars to the sun, a cluster contains thousands of stars. These stars share incredible similarities, all having formed at the same time millions of years ago and with the same chemistry. The only difference between the individual stars is their mass, and mass happens to be the primary factor that controls how stars evolve (e.g., how long they live for, how bright they become and how they die).
So, observations of each individual star cluster give us a snapshot of how stellar evolution has shaped a population with that age, and we can complete a picture of stellar evolution by observing many clusters with different ages. As a result, star clusters anchor much of our knowledge of the universe.
CNN: How exactly do stars evolve over time?
Kalirai: We are used to thinking of the stars as fixed points in the night sky, but they actually go through a life cycle, just like humans. Newborn stars are very active and energetic, kind of like my twins. Stars in their middle years are kind of boring (dare I say, like our parents), and can spend billions of years not doing much other than converting hydrogen into helium. Toward the end of their lives, stars become "cool" again, kind of like grandparents are "cool." The lifetimes of stars are so much longer than human lifetimes that we see them as being fixed over generations. But they all evolve from stellar birth to stellar death.
CNN: What is the main goal of your research program?
Kalirai: The main goal of my research is to understand the details of how stars like our sun, including those that are a little more and a little less massive, change over time. For billions of years, these stars will remain at the same brightness and temperature. This is great for humans on Earth since it gives us a stable climate. After the hydrogen in the sun is exhausted, the sun will become a stellar cinder and simply cool over time. We call this state, the end state of 98% of all stars, white dwarfs.
All of the action in stellar evolution occurs between these two phases, when, over a relatively short time scale, stars swell up into "giants" and spill their outer materials into space. The detailed understanding of this process, of how stars dramatically change, is fundamentally important to many research areas in astronomy. After all, the light that we see from distant galaxies is really just millions of individual stars at the tip of their luminous evolution.
CNN: If the sun will experience this dramatic change, what is the fate of our planet Earth?
Kalirai: The Earth is orbiting the sun at a distance of about 90 million miles. When the sun runs out of hydrogen in its core, it will begin burning hydrogen in a shell around the core and become very luminous and bloated. The outer layers of the sun will actually reach the Earth, and so the oceans will evaporate and our planet will be fried. Sorry! Fortunately for us, this won't happen for several billions of years. | <urn:uuid:3e1d457b-40e9-4893-9f74-0459fd838b37> | 3.03125 | 1,344 | Audio Transcript | Science & Tech. | 48.38367 |
12:07 01 February 2010
The songs of whales and dolphins can be beautiful to the ear. Now acoustics engineer Mark Fischer has created a way to make them visually pleasing too. What's more, his technique captures more information about the sound than traditional ways of visualising whalesong.
Image 1 of 10
Humpback whale call
This is Fischer's representation of the low-frequency moans and cries of a humpback whale
's mating song, with the time axis running anticlockwise.
The sound for this graph was recorded in Hawaii.
Audio: listen to the humpback whale's mating song
(Image: Science Photo Library/AguaSonic Acoustics) | <urn:uuid:dcacea23-5f3e-41f1-99a4-21ead567cfdb> | 3.453125 | 144 | Truncated | Science & Tech. | 49.354286 |
|Ocean Dumping and Ship Wastes||
Maintained by IMO
|This topic deals with ocean dumping and ship wastes, deliberately dumped under controlled conditions. It includes nuclear waste disposal, sewage outfalls, land-based materials or those that derive from shipping, such as from cargo transport ships and passenger ships. For accidental discharge, see Pollution and Degradation.
|Dumping of Wastes and Other Matter|
|Internationally, dumping of wastes and other matter is controlled by the London Protocol 1996 to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972 (the London Convention), administered by the International Maritime Organisation. |
The following materials may be dumped under controlled conditions
About 80-90% of the material dumped at sea results from dredging and currently amounts to hundreds of millions of tons a year. Of the total material dredged, probably two-thirds is associated with operations to keep harbours, rivers and other waterways from silting up. The other third involves new works. Future dredging operations and the requirement for ocean disposal are expected to follow current trends. The ocean disposal of dredged material represents only 20-22% of the total dredged and the remainder is mostly dumped in internal waters, or placed on land for disposal or productive purposes.
- dredged material;
- sewage sludge;
- fish wastes;
- vessels and platforms;
- inert, inorganic geological material (e.g., mining wastes);
- organic material of natural origin;
- bulky items primarily comprising iron, steel and concrete; and
- carbon dioxide streams from carbon dioxide capture processes for sequestration (CCS).
Approximately 10% of dredged sediments are heavily contaminated from a variety of sources including shipping, industrial and municipal discharges, and land runoff. Typical contaminants include heavy metals, such as cadmium, mercury and chromium; hydrocarbons, such as oil; organochlorines such as pesticides; and nutrients such as nitrogen and phosphorous. Disposal at sea of these materials carries the possibility of acute or chronic toxic effects on marine organisms, and potential contamination of human food sources.
|It was recognized that ships, especially oil powered ships, could cause pollution and both the United Kingdom and the United States introduced legislation in the 1920s to curb discharges of oil resulting from operations such as tank cleaning. Attempts to tackle the problem at an international level were unsuccessful, however, and the outbreak of World War II resulted in the problem being deferred. |
The potential for oil to pollute was finally recognised by the International Convention for the Prevention of Pollution of the Sea by Oil 1954. The Convention provided for certain functions to be undertaken by the International Maritime Organization. OILPOL 54 prohibited the dumping of oily wastes within a certain distance from land and in 'special areas' where the danger to the environment was especially acute.
printed on 2013/05/26 04:48:26 | <urn:uuid:cf2114d5-1961-4f51-bc92-efcbf6b6f61c> | 3.765625 | 608 | Knowledge Article | Science & Tech. | 22.149579 |
Egg Drop - Newton's Law of Inertia
Demonstrate gravity, motion, and other forces with this incredible science trick.
The Egg Drop is a classic science demonstration that illustrates Newton's Laws of Motion, namely inertia. The challenge sounds so simple... just get the egg into the glass of water, but there are a few obstacles. The egg is perched high above the water on a cardboard tube, and a pie plate sits between the tube and the water. Still think it's easy? Sir Isaac Newton does.
- Cardboard tube
- Pie pan
- A large drinking glass
- Tray (optional)
- Coloring Tablets (optional)
Warning: Always wash your hands well with soap and water after handling raw eggs. Some raw eggs contain salmonella bacteria that can make you really sick!
- Fill the large drinking glass about three-quarters full with water.
- Center a pie pan on top of the glass.
- Place the cardboard tube on the pie plate, positioning it directly over the water.
- Carefully set the egg on top of the cardboard tube.
- With your writing hand, smack the edge of the pie pan horizontally. Don't swing up, and don't swing down! It’s important that you hit the pie pan horizontally and use a pretty solid hit, so plan on chasing the plate and tube.
- Your astonished guests will watch the egg plop nicely into the water. It’s even more fun to watch someone else try to drop the egg. Science is so cool!
Take It Further!
- Try setting up a tray (like one that you would get from a fast food restaurant) on top of five glasses. USe five tubes and five eggs and see if you are an egg drop master! *HINT* The angle that you hit the tray from can make all the difference.
- Add coloring to the water in your egg drop for added effect.
- Try testing longer tubes, more or less water, different liquids in the glass, different water containers, and heavier or lighter falling objects.
How does it work?
Credit for this one has to go to Sir Isaac Newton and his First Law of Motion. He said that since the egg is not moving while it sits on top of the tube, that’s what it wants to do - not move. You applied enough force to the pie pan to cause it to zip out from under the cardboard tube (there’s not much friction against the drinking glass). The edge of the pie pan hooked the bottom of the tube, which then sailed off with the pan. Basically, you knocked the support out from under the egg. For a brief nanosecond or two, the egg didn’t move because it was already stationary (not moving). But then, as usual, the force of gravity took over and pulled the egg straight down toward the center of the Earth.
Also, according to Mr. Newton’s First Law, once the egg was moving, it didn’t want to stop. The container of water interrupted the egg’s fall, providing a safe place for the egg to stop moving so you could recover it unbroken. The gravity-pushed egg caused the water to splash out. Did someone get wet?
November 20th, 2012
Click the thumbnail below to see the video.
CJP - September 29, 2012
It's important to note that it is not only inertia that keeps the egg from flying away like the pan and the tube did. You only hit the pan- so why did the tube go flying? Because the edge of the pan hit it. So why didn't the tube then hit the egg and send it flying in the same direction as the pan and tube? The tube is hit on the lower edge, so it rotates (rotational motion) as it is flying away (translational motion). This rotational motion causes it to roll out from under the egg which then allows gravity to take over and drop the egg straight down into the water.
cathy - May 8, 2011
My second grade son had to do a "how to" presentation and we decided on this experiment. His presentation for the whole class was flawless. He then asked for a volunteer from the class to try the experiment...went flawless again. Then he had the teacher try! She wasn't listening to well to the directions given by her student, my son, and she smacked the pie plate and the glass over in one big swoop of her arm sending the egg and water flying!! It was hilarious. After a few more attempts she finally got it. I guess she needs a few tips on listening:)
Preschool Egg Drop
Miss Donna - March 16, 2011
This demonstration was a huge hit with my 4 year-old group!
DIY science experiment
Kevin - November 7, 2010
I took more than 3 hours trying to find a good DIY experiment on the web. This was the only one I could find that fulfilled and even exceeded my expectations.
the egg drop
jennifer ruskin,fl,usa - November 21, 2009
I have to say that egg drop trick was so cool i had to use 3 eggs because my famialy was real nevous and tjey didnt have faith in thereselfs.thank you for showing that experiment.Also I did thta experiment in science class yesturday when my teacher said to go on this website.Well also we have a science fair project due the week before christmeas.First i was going to do electricity but now im not.Thank you very much. | <urn:uuid:6f571732-5901-4217-afc9-0ade92ca96f6> | 3.640625 | 1,161 | Tutorial | Science & Tech. | 73.010048 |
A map of Earth's tectonic plates. Plate boundaries are shown in red. Learn more about the geologic features related to Earth's tectonic plates at This Dynamic Planet
Click on image for full size
Modified from USGS
Many forces change the surface of the Earth over time. The largest force that changes our planetís surface is movement of Earth's outer layer in a process called plate tectonics.
As shown in this picture, the Earthís outer layer, called the lithosphere, is broken into plates which fit together like a jigsaw puzzle. These plates move very slowly (2 inches per year).
Plates crash into each other at subduction zones.
Plates pull apart at spreading ridges.
Plates slide past each other along large faults.
Shop Windows to the Universe Science Store!
Print copies of Spring 2011 issue of The Earth Scientist
, focusing on modernizing classroom seismology education, are available in our online store
. Thanks to IRIS
, the issue is also available as a free pdf
online at NESTA
You might also be interested in:
Many kinds of surface features are clues to a sliding lithosphere. Two types of features can form when plates move apart. At ocean ridges, the crust splits apart to make room for molten mantle rock. Continental...more
When two sections of the Earth's crust collide, one slab of lithosphere can be forced back down into the deeper regions of the Earth, as shown in this picture. The slab that is forced back into the Earth...more
A team of scientists from the United States was invited to visit Haiti in late January 2010 to look into the cause of the magnitude 7 earthquake that happened there. While there, the geologists will collect...more
The ground underfoot might seem like itís not going anywhere but it is. It moves. If it moves all of a sudden the ground shakes. Thatís an earthquake! Earthquakes happen as pieces of the Earthís crust...more
Newly Found Rock May Prove Antarctica and North America Were Connected There are lots of rocks in Antarctica. But the one that scientists just found is very special. It shows that Antarctica and North...more
Mountains are built through a general process called "deformation" of the crust of the Earth. Deformation is a fancy word which could also mean "folding". An example of this kind of folding comes from...more
Plates at our planetís surface move because heat in the Earthís core causes molten rock in the mantle layer to flow. We used to think the Earthís plates just surfed on top of the moving mantle, but now...more | <urn:uuid:f97fd6c0-59d7-43e2-aea6-cbd8ff58e08c> | 4.25 | 545 | Content Listing | Science & Tech. | 61.490923 |
What's news in science? Sensor System Runs On Electricity Generated By Trees. For my study of what's new, and news worthy in today's modern science, I found a couple articles, describing that MIT is constructing a new type of sensor on trees that detect several amounts of data. This is particularly important due to the world’s energy crisis. Anywhere we can get clean electricity and energy is always important and beneficial in the long run. This topic is also potentially interesting because of the several uses that come from harnessing natural energy from trees.I initially found an article by browsing on ‘Google’ from science news searches and found “Can Electricity From Trees Power Gadgets?” from dailygalaxy.com. I learned from reading this source that the scientific explanations are simplified for a general audience to understand. This article is just a basic overview of the science and research of the energy captured from trees. The second source I found was from ‘Google’ after browsing under searches of ‘tree sensor systems’, I came up with an article from MIT discussing the science and process of how energy is harnessed from trees, where the energy comes from, and the analysis and research of the subject in more detail than the first source.
To summarize and evaluate the first source I accessed, according to dailygalaxy.com, a new sensor system is under development from MIT that runs on electricity generated by 'ordinary' trees. Trees are capable of self-sustaining a reliable source of electricity. MIT researchers believe they can power a network of sensors connected directly to trees to perform a variety of tasks. While a tree may not seem like much of a source of power, according to the article trees have a "trickle charge" that adds energy up. The article quotes, "just like a dripping faucet can fill a bucket over time," said Shuguang Zhang, one of the researchers on the project and the associate director of MIT's Center for Biomedical Engineering (CBE). The U.S. Forest Service says that manually recharging or replacing batteries in remote automated weather stations makes things impractical and costly, especially since they are usually located in hard-to-reach places. This would be alleviated by the new sensor system. In the past these weather sensors and forest fire sensors were run off batteries. Now MIT has developed new sensors that can derive their own power from the tree itself. The system would bypass power issues by tapping into the trees very own self-sustaining power supply. This would utilize energy we have on earth, save batteries, and save manual hassle and cost changing them. It would also alleviate landfill usage from batteries. Each sensor is equipped with a battery that can be slowly recharged using electricity generated from the tree. The sensors would be self-sustained with power as a result of the energy emanating from trees. The uses for harnessing the trees power could serve as what the article refers to as “silent sentinels,” sensors along the nation's borders to detect potential threats such as smuggled radioactive materials. The sensors can also track forest fire models and data, as well as detect and prevent fires, by sending early reports to authorities. The new self powered sensor system is a scientific innovation that harnesses secure and efficient data of weather, forest fires, and potential smuggling effectively. How the system transmits information, is from the tree producing enough electricity to allow temperature and humidity sensors to wirelessly communicate signals of information four times a day, or immediately if there's a fire. Each signal hops from one sensor to another, until it reaches an existing weather station that transmits the data by satellite to a forestry command center in Boise, Idaho. The article then proceeds to discuss where this energy from trees actually comes from, and scientifically how the self-powered sensor system works in general terms.
Exactly how is the generating power produced in trees accessible for us to take advantage of? According to the article, MIT colleagues recently reported the answer in the Public Library of Science. "It's really a fairly simple phenomenon: An imbalance in pH between a tree and the soil it grows in," said Andreas Mershin, a postdoctoral associate at the CBE. Voltree Power and the MIT team plan to test the wireless sensor network in the spring on a 10-acre plot of land provided by the Forest Service. Christopher J. Love, creator of the ‘bio-energy harvester battery charger module’ and the ‘sensors’ at MIT said, "We expect that we'll need to instrument four trees per acre…Right now we're finalizing exactly how the wireless sensor network will be configured to use the minimum amount of power." Love also suggests that unskilled workers can design the system for easy installation. If this is all successful in the near future it will function as a wonderful scientific revolution for data collection, weather collection, fire prevention, and smuggling detection.
My opinion on this innovation, in which the original sources don't have, is that we need to be doing things like this more often. We have the capabilities to innovate, create, develop and research new beneficial inventions for our society. As a nation, and as a world, we should have institutions like MIT and others developing and researching new ways to harness energy and other developments more often to propel our existence in prosperity for the future, and in contemporary society. We have the money and the capabilities to develop innovations like this more often, and to utilize these developments like this more often. Instead we have our priorities in racking up debt in Iraq, ruing the economy, and doing other political malfunctions as a country (cough *Bush* cough) instead of developing our time, energy and money into developments like this that save energy, and would strive for the future. This piece of new scientific news matters to me because harvesting energy in new ways is something we need to do more frequently. Anywhere where I see innovations in the right direction of energy preservation, matters to me. It should matter to our class and the rest of the world for the same reasons; the energy crisis is very pressing right now. In general, this innovation doesn’t have a large effect on us, however the data collection from the sensors provides a better way to study weather and forest fire patterns, which indirectly will have an effect on us. This strictly benefits data collection more than us personally. The sources appeared where they did because I accessed the more general article first, through Google, and then I found where that article originated from with more detail on the second source, once I put more effort in research. If this innovation is completed and tested successfully from MIT, then in my mind it will definitely be revolutionary since we found a way to harness energy that’s coming from the very Earth we step foot on. | <urn:uuid:e9bd421c-e574-444d-9851-8ee53ace9bc1> | 2.984375 | 1,392 | Personal Blog | Science & Tech. | 37.227456 |
Want to have an anxiety attack? Think about this. This should put things in perspective for us.
The Ogallala aquifer is located under the Great Plains, covering parts of eight states including: Texas, New Mexico, Oklahoma, Kansas, Colorado, Wyoming, Nebraska and South Dakota. This area is considered the breadbasket of America and produces most of the agricultural bounty our country depends on for food and exports. According to an article in Scientific American, more than 90% of the water pumped out of the aquifer is used to irrigate crops, supporting $20 billion of food and fiber production. It supports almost one-fifth of US production of wheat, corn, cotton, and cattle.
The problem? The Ogallala will run out of water, and at the rate we’re going, soon. Scientists have estimated that it would take 6,000 years for the aquifer to naturally replenish itself, but we are taking water at much faster rates. Within the boundaries of the North Plains Groundwater Conservation District, the water level is dropping at 1.74 feet per year.
Hasn't anybody explained the importance of the economy to mother nature?
You heard it from me first. | <urn:uuid:1296e90d-1f3b-4a11-b61e-44579127e5b7> | 3.078125 | 247 | Comment Section | Science & Tech. | 51.258044 |
A space station is a man-made structure that is designed for people to live on. A space station is distinguished from other manned spacecraft by its lack of major propulsion or landing facilities - instead, other vehicles are used as transport to and from the station. Space stations are designed for medium-term living in orbit, for periods of some months.
Space stations are used to study the effects of long-term space flight on the human body as well as to provide platforms for greater number and length of scientific studies than available on other space vehicles.
Past and present space stations:
Since the flight of Skylab 2, all manned spaceflight duration records have been set aboard space stations. The duration record of 437.7 days was set aboard Mir in 1994-1995. As of 2003, 3 astronauts have completed single missions of over a year, all aboard the space station Mir.
Some space station designs have been proposed which are intended as long-term space habitats for large numbers of people, essentially "cities in space" where people would make their homes. Thus far all such designs are only hypothetical, and have never been seriously considered for actual implementation.
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Comprehensive and updated resource on ISS by NASA. Includes operational news, wide range of background material, archives, image gallery and planned missions.
Marshall Space Flight Center
Provides a fact sheet outlining the center's role in the space station, in particular payload operations and microgravity research.
Space Station Science Operations
Features news and overview of all scientific experiments onboard the station. Includes a variety of background material and links.
Provides news briefs and links related to the station with emphasis on radio amateurs. Includes call signs of astronauts.
Provides a compilation of current status, crew and plans for the construction of the station and its elements.
The Automated Transfer Vehicle
Includes project overview, news and events from the team in the European Space Agency managing the development of this supply spacecraft for the station.
Data Management System
Provides factsheet for the DMS-R computers, in the Russian Service Module 'Zvezda', providing the overall control of the Russian segment.
Provides design and project overview of the main observation post on the station.
Node 2: Connecting Module
Offers data sheets on the module connection the truss structure and the US laboratory to other elements.
Node 3: Connecting Module
Offers data sheets on the module that connects elements and house a number of life support systems.
The European Robotic Arm
Provides project overview and data on the walking robot planned to service the Russian segment.
Provides comprehensive project overview and news from the prime Russian ISS contractor, with emphasis on the Russian elements.
Features overview of a French center for microgravity experiments and space station utilization. Includes list of past missions.
Potomac Institute Commercialization Study
Features a report resulting from a NASA grant to a policy studies organization. [PDF 303K/82 pages]
Overview of ISS activities and news by a German provider. Includes mission, crew aspects and supporting material.
Provides a collection of briefs and multimedia material compiled from other web sources.
Features the prime contractor's overview of the design, its assembly sequence in space and scientific use.
Space Today Online
Offers e-zine with comprehensive news and coverage of all aspects of space stations by a space writer. Includes historical material on previous stations.
The History of Space Stations
Features a brief history article on the space stations by a writer and space professional.
Provides overview of the shuttle mission with Chris Hadfield that delivered the Canadian robot arm to the space station in 2001.
How Space Stations Work
Illustrated tutorial about what a space station looks like, what will it be like to live and work in space, and what problems are involved in building one.
CBC News: The International Space Station
News article with particular emphasis on the Canadian role.
CBC News: Canadarm2
News account providing an in-depth look at the new Canadian robot arm for the space station.
Offers summaries of the construction and expeditions to the space station, by an author specializing in Russian space history.
Scientific American: Missed Deadlines
News article about difficulties with the Russian participation (1998).
ESA - Human Space Flight
Features overview of European participation in the International Space Station, with projects, news and events.
Belgian International Space Station User Support Center
Provides contacts, documentation, news and events for the scientific users of the space station.
Provides comprehensive space station news coverage by a television producer. Includes picture galleries, virtual tours.
Earth Sciences and Image Analysis
Includes a searchable, updated database of Earth photos made from the space station's windows.
Space Station User's Guide
Includes updated news on all aspects of the space station from an on-line news provider.
Houston Chronicle: Space Station
Provides regular news coverage and an archive of ISS-related articles from a newspaper in Texas.
Kennedy Space Center
Offers overview of the ISS payload and system launch processing. Includes outreach, multimedia and live feeds from the Space Station Processing Facility.
PBS - Space Station : The Series
Offers an overview of a television series. Includes a variety of supporting material for the public.
The Columbus Laboratory
Includes project overview, news and events from the team in the European Space Agency managing the development of this module of the ISS.
Facility Support Center for BIOLAB
Contains overview of a facility in Switzerland supporting users of the BIOLAB experiment.
The Crew Return Vehicle
Overview of a project to develop a manned spacecraft to return the crew to Earth in case of an emergency.
Human Presence in Space
Offers an overview and updates on the ISS project with emphasis on the Canadian participation. Includes links to information about the Canadian Space Agency, its projects, and Canadian astronauts.
Offers current and past station official status reports. Provided by the flight operations authority.
Future of Canadian Space Exploration
Includes a brief introduction on Canada's involvement in the space station.
CNN - City in Space
News coverage from CNN. Includes interactive multimedia. | <urn:uuid:20c6fb18-3fc4-4a39-8c21-c66927d55aeb> | 3.796875 | 1,285 | Knowledge Article | Science & Tech. | 30.718469 |
DNA-RNA triplex formation is well-documented. It was originally analysed in simple model polynucleotides where the DNA has a polypurine strand and the RNA has a polypyrimidine, e.g.
but it is now known to occur in more complex sequences. One of the best studied examples is in the promoter of the human DHFR gene:
Gee, J. E. et al.(1992) Triplex formation prevents Sp1 binding to the dihydrofolate reductase promoter. J. Biol. Chem. 267, 11163–11167
In this work the oligonucleotide GR19 was shown to bind in a triple helix to SpI binding site I in the DHFR promoter (CR19 was used as a control). Triplex formation was detected by gel shift, and the specificity was confirmed by DNase I footprinting.
This effect is part of the regulation of DHFR - the transcript from a minor upstream promoter binds to the major promoter, see:
Martianov, I. et al. (2007) Repression of the human dihydrofolate reductase gene by a non-coding interfering transcript. Nature 445: 666-670
The structure of these triple helices involves a combination of Watson-Crick base pairing in the DNA duplex together with Hoogsteen base pairing in the RNA-DNA interaction:
Figure taken from:
Morgan, A. R. & Wells, R. D. (1968) Specificity of the three-stranded complex formation between double-stranded DNA and single-stranded RNA containing repeating nucleotide sequences. J. Mol. Biol. 37, 63–80 | <urn:uuid:fa7336d3-e559-4aa6-88ab-86ac03a89f53> | 3.171875 | 349 | Q&A Forum | Science & Tech. | 59.54096 |
A pest-eating ladybug attacks an aphid.
As angry debates about genetic modification continue, GM crops are quietly going about their business—and producing some positive side effects. In China, with Bt cotton reducing the need for insecticides, pest-eating bugs have rebounded and brought natural pest control with them.
China’s genetically modified cotton is not new. Farmers used to spray their cotton with a protein, naturally produced by the Bacillus thuringiensis (Bt) bacteria, which is toxic to certain insects. As research into genetically modified crops advanced, scientists implanted the cotton itself with the Bt genes that code for production of the insect toxin, creating so-called “Bt cotton” and alleviating the need for the sprayed insecticide. Since China approved its use in 1997, Bt cotton has proved itself particularly effective against the cotton bollworm moth, reducing the costs and side effects of spraying pesticides, but it has had may also decrease the number of non-pest insects compared with organic fields.
With the advent of Bt cotton, pesticide use became specialized, only affecting insects that both were vulnerable to Bt’s toxin and that fed on cotton, which allowed the populations of other insect species to rebound. Some of the now-thriving species, like mirids, are pests, but others eat pests, and their recovery is making natural bug control possible.
The AquAdvantage salmon.
When most people say “genetically modified organism,” they usually mean a plant—corn, perhaps, or an eggplant. But that may soon change. The FDA has completed its analysis of the first genetically modified animal likely to hit supermarket shelves: the AquAdvantage salmon, made by Massachusetts-based AquaBounty Technologies, Inc. Thanks to some added genes, the salmon grows 2-6 times the size of a normal Atlantic salmon in half the time, promising some respite for the planet’s heavily taxed natural fish stocks, a third of which are near extinction or exhaustion. Talking Points Memo’s IdeaLab reports that a source close to the review process says that the FDA’s environmental impact statement, which looks at what effect the salmon will have on the environment and seems to be favorable, has been passed on to the White House’s Office of Management and Budget.
As always with genetically modified organisms, there are questions about how the salmon’s manufacturers plan to keep its genes from getting loose in the environment. AquaBounty has developed a way to make the fish sterile, which would make spreading their genes quite tricky. At the moment, however, it only works on 98% of the salmon. Additionally, the company is only seeking approval for growing the fish in large, land-locked tanks with double-thick walls. While giant nets teeming with fish in the middle of the ocean are a sight more commonly associated with aquaculture, inland tanks make the risk of modified fish escaping much smaller. | <urn:uuid:81bff8c7-9749-4f2e-a739-2be93e3090d6> | 3.0625 | 614 | Personal Blog | Science & Tech. | 34.53291 |
This is an introduction to the Cobra programming language. It assumes you already know one or more high level languages such as Python, C#, Java, C++, Visual Basic, PHP, Ruby, etc.
Cobra is an imperative, high-level, object-oriented language with direct support for contracts, unit tests and compile-time nil tracking. It has namespaces, classes, interfaces, generics, methods, properties, indexers, variable number of args, overloading, exception handling and garbage collection. It has a high-level syntax with indented blocks, doc strings, list literals, dictionary literals, set literals, in operator, slicing, for expressions, if expressions, assert, and more.
That may sound like a lot, but its complexity is in the same neighborhood as other high-level languages, most of which have been accumulating features since their initial release (for example, Python and C#).
Let's get started with "Hello, world.":
Cobra uses indentation to denote code structure since adept programmers do this anyway in languages that don't even require it (C#, Java, C++, etc.). In Cobra, one INDENT is accomplished by one TAB or four SPACES. Mixing tabs and spaces in a single line is not allowed and will produce a compiler error as mixing the two is always problematic.
Cobra is supported on both Microsoft(R) Windows(R) as well as Unix-like systems (Mac, Linux, etc.) via Microsoft .NET and Novell Mono, respectively. At the command line, on Windows:
> cobra hello.cobra Hello, world.
And on Posix:
$ cobra hello.cobra Hello, world.
A hello.exe is left after the execution and, if you want, you can compile a Cobra program without running it. In the examples below, the program is then run directly:
Windows: > cobra -compile hello.cobra > hello Hello, world.
Posix: $ cobra -compile hello.cobra $ mono hello.exe Hello, world.
You can specify "-c" for "-compile". Now let's print the Fibonacci sequence:
1 1 2 3 5 8 13 21 34 55
Note that a statement like n = 10 is really a shorthand for n as int = 10. Cobra infers the type for a local variable from the value it is initialized with. The type is fixed from that point on—attempting to assign a string to n will give a compile-time error. Type inference allows for clean, quick coding while the fixed type enables better error checking and faster execution.
As a convenience, you can assign multiple items at a time:
Let's keep the main small and break out Fib into more library-oriented code:
Now Fib.compute can be used from anywhere and the number of elements to compute can be passed as an argument. But its output is still going directly to the console instead of being returned to the caller. We can fix that by having it return a list:
1. 1 2. 1 3. 2 4. 3 5. 5 6. 8 7. 13 8. 21 9. 34 10. 55
The List<of int> is an example of a generic where type arguments are passed to construct the final type. In this case, the type is spoken as "list of int". Generics increase readability, type safety, and sometimes, performance.
To instantiate any class, whether generic or not, call it with parens ()s. Some classes will, of course, take arguments for their initialization.
Also, introduced in the above example is string substitution where any Cobra expression can be embedded in a string by surrounding it with square brackets. This turns string literals into a kind of mini-templating language.
And finally, the += operator is a shorthand for left = left + right and may also be more efficient.
Now let's take a more object-oriented approach by making the Fib class an actual list of the Fibonacci numbers, as opposed to a "computer of them":
The above program makes Fib a subclass of List<of int> by stating inherits List<of int>. Then an initializer is declared for the class with cue init. Although it looks like an ordinary method, init has some special rules:
- init cannot return any values—it's job is to operate on the current object
- init can call another init of itself or its base class, but the call must be the first statement
- init methods are not inherited
Note the init has no is shared modifier because it is intended for the object level, not the class level. In fact, most methods (properties, inits, etc.) are not shared.
The base.init(count) call is taking advantage of the fact that the List<of> base class provides an init(capacity as count) to set the initial capacity of the list. (The list can still grow in size past that capacity on any call to add.)
The .add(b) is an invocation on the current object. It is like obj.add(b), but with the obj assumed to be this. The leading period is a cue to anyone reading the code, and when writing the code, it is a cue to the IDE to provide autocompletion choices limited to the current object.
Where to next?
Now that you know some basic syntax and capabilities, things get much more interesting. Read about Coding for Quality. | <urn:uuid:cc70db51-5bb5-4aa9-aabf-dbfbf9d6c5df> | 2.765625 | 1,162 | Documentation | Software Dev. | 58.511833 |
The reproductive biology of rare rangeland plants and their vulnerability to insecticides
Gary L. Cunningham
United States Department of Agriculture Animal and Plant Health Inspection Services
Ecology & conservation
Tepedino, V.J. 2000. The reproductive biology of rare rangeland plants and their vulnerability to insecticides. Pp. III.5-1 – 10; In: Cunningham, Gary L.; Sampson, Mike W., tech coords. Grasshopper integrated pest management user handbook. Tech. Bull. 1809. Washington, DC: U.S. Department of Agriculture, Animal and Plant Health Inspection Service. (Paginated and published by sections.) http://www.sidney.ars.usda.gov/grasshopper/Handbook/III/iii_5.htm
This document is currently not available here. | <urn:uuid:903cb8b9-f05e-4361-a87f-d6ff874e0a47> | 2.734375 | 175 | Truncated | Science & Tech. | 39.849832 |
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container.
A desiccator is a heavy glass or plastic container used in practical chemistry for making or keeping small amounts of materials very dry. The material is placed on a shelf, and a drying agent or desiccant, such as dry silica gel or anhydrous sodium hydroxide, is placed below the shelf.
Often some sort of humidity indicator is included in the desiccator to show, by color changes, the level of humidity. These indicators are in the form of indicator plugs or indicator cards. The active chemical is cobalt chloride (CoCl2). Anhydrous cobalt chloride is blue. When it bonds with two water molecules, (CoCl2•2H2O), it turns purple. Further hydration results in the pink hexaaquacobalt(II) chloride complex [Co(H2O)6]2+.
Biology and ecology
In biology and ecology, desiccation refers to the drying out of a living organism, such as when aquatic animals are taken out of water, or when plants are exposed to sunlight or drought. Ecologists frequently study and assess various organisms' susceptibility to desiccation.
In broadcast engineering, a desiccator may be used to pressurize the feedline of a high-power transmitter. Because it carries very high electrical power levels from the transmitter to the antenna, the feedline must have a good dielectric. Because it must also be lightweight so as not to overload the radio tower, air is often used as the dielectric. Since moisture can condense in these lines, desiccated air or nitrogen gas is pumped in. This pressure also keeps water or other dampness from coming in the line at any point along its length.
See also
||This article needs additional citations for verification. (October 2009)| | <urn:uuid:e70e211a-1c0d-400e-a8a1-66ce5bd523bc> | 4.15625 | 428 | Knowledge Article | Science & Tech. | 35.816659 |
Hypernova and Gamma Ray Bursts
Nova last night was on Hypernovae (the web site is here but is only so so). A hypernova is a supernova for a specific type of star (a "Wolf-Rayet") that is very hot and massive. When it dies, the core of the star doesn't just burn but collapses in on itself creating a blackhole at the center of the star. In a matter of minutes the black hole absorbes the rest of the star. From here is gets really wierd - the black hole has to conserve the angular momentum of the star but can only spin so fast so it must emit a set of gamma ray jets to get rid of some of the angular momentum (it's not really clear why the energy is emitted in this way). The gamma ray burst produced lasts from seconds to an hour and can be observed on earth. Gamma rays have been observed for a long time but only recently has their production been tied to the death of stars. | <urn:uuid:2dd8ae03-c7a8-449a-a3e8-a7860691bf31> | 3.0625 | 204 | Personal Blog | Science & Tech. | 61.625227 |
Manual Section... (3) - page: tgamma
NAMEtgamma, tgammaf, tgammal - true gamma function
double tgamma(double x);
float tgammaf(float x);
long double tgammal(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
DESCRIPTIONThe Gamma function is defined by
Gamma(x) = integral from 0 to infinity of t^(x-1) e^-t dt
It is defined for every real number except for nonpositive integers. For nonnegative integral m one has
Gamma(m+1) = m!
and, more generally, for all x:
Gamma(x+1) = x * Gamma(x)
Furthermore, the following is valid for all values of x outside the poles:
Gamma(x) * Gamma(1 - x) = PI / sin(PI * x)
RETURN VALUEOn success, these functions return Gamma(x).
If x is a NaN, a NaN is returned.
If x is positive infinity, positive infinity is returned.
If x is a negative integer, or is negative infinity, a domain error occurs, and a NaN is returned.
If the result overflows, a range error occurs, and the functions return HUGE_VAL, HUGE_VALF, or HUGE_VALL, respectively, with the correct mathematical sign.
If the result underflows, a range error occurs, and the functions return 0, with the correct mathematical sign.
ERRORSSee math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
- Domain error: x is a negative integer, or negative infinity
- errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised (but see BUGS).
- Pole error: x is +0 or -0
- errno is set to ERANGE. A divide-by-zero floating-point exception (FE_DIVBYZERO) is raised.
- Range error: result overflow
- errno is set to ERANGE. An overflow floating-point exception (FE_OVERFLOW) is raised.
glibc also gives the following error which is not specified in C99 or POSIX.1-2001.
- Range error: result underflow
- An underflow floating-point exception (FE_UNDERFLOW) is raised.
- errno is not set for this case.
VERSIONSThese functions first appeared in glibc in version 2.1.
CONFORMING TOC99, POSIX.1-2001.
NOTESThis function had to be called "true gamma function" since there is already a function gamma(3) that returns something else (see gamma(3) for details).
BUGSIf x is negative infinity, errno is not set (it should be set to EDOM).
SEE ALSOgamma(3), lgamma(3)
COLOPHONThis page is part of release 3.24 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.
This document was created by man2html, using the manual pages.
Time: 15:27:01 GMT, June 11, 2010 | <urn:uuid:685864d0-c5a4-40e9-931b-9859bdd45346> | 2.96875 | 755 | Documentation | Software Dev. | 57.602456 |
In this section you will learn about the getLocalHost() method to print the Host name as well as the IP Address of the local system. For do for the same we have to call InetAddress class then we need to create a object, in which we store the local host information. Then after we use the print command to print the stored value of the InetAddress object local. The example for the above process is as under.
Here is the Code of the Example :
The output of the above example is as under, In which the host name of the local system is Comp20 and the IP address is 192.168.10.103.
Here is the Output of the Example :
Local IP Address is : comp20/192.168.10.103
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:5ff8e50c-aaa9-4ce9-b700-ebbffb02e40f> | 3.09375 | 201 | Documentation | Software Dev. | 72.948671 |
This computer image shows seven cosmic ray
muons (yellow lines) going through the detector simultaneously.Charged
particles like these emit a cone of Cherenkov light which
travels through the water and hits the photomultiplier tubes (PMT's)
covering the six walls of the detector. Each slash represents
one Cherenkov photon hitting a PMT. The colors indicate the time
the PMT was hit. The color scale at left gives the time in nanoseconds
(ns). The scale is negative, starting around -300 ns and ending
around -220 ns. A typical cosmic ray takes about (300-220)=80
ns to traverse the 80 ft detector at a speed of about one foot
per ns (essentially the speed of light).
The paths of the muons are reconstructed from
the PMT data to within an accuracy of a few degrees.
The above 7-muon event is rare..... muons usually
go through one or two at a time.
The event at left is even rarer, occurring only
about once a week. It is a muon going through upwards from the
BOTTOM (indicated by purple rectangles)
and exiting at the TOP (red rectangles).
This muon was not generated in the atmosphere
above (like the down-going ones) but in the earth itself below
the detector. A high energy neutrino generated in the atmosphere
on the other side of the world passed all the way through the
earth and happened to interact just below the detector to produce
the up-going muon.
This event is also an upward-going muon that enters
the BOTTOM near the NORTH wall (back wall in this view). The muon
doesn't go all the way through the detector but skims along the
NORTH wall and stops in the water about 2/3 the way through.
This muon generates a Cherenkov cone that can be
seen developing in time by mousing-over
(not clicking) on the buttons.
The yellow squares in picture 5 show where the outside
of the Cherenkov cone intersects the NORTH, TOP, and EAST walls.
The pictures are about 20 ns apart in time.
NOW.... HOW TO DETECT DECAYING
The pictures below illustrate four different
ways to view the same event,
an upward-going muon which starts inside the detector and goes
about 7 ft
before slowing down and stopping in the water.
The muon was produced by an upward-going neutrino which interacted
with a nucleon (proton or neutron) in the water.
Such tracks make a single thin Cherenkov cone which lights up a ring
The cone has a (half) opening angle of 41 deg so
the size of the ring of tubes will depend on how far away from the wall
the track started.
Looking down into the tank we see
a large Cherenkov ring hitting the TOP, SOUTH, WEST, and NORTH
walls. It's difficult to discern a ring in this view.
The ring is much easier to see in
this "fisheye" view in which the observer's eye
is put at the origin of the muon track.
In this view the PMT hits are projected
onto a cylinder whose center is at the "fisheye".
The cylinder is then unrolled to be a plane. The blue and purple
hits are due to photons that scattered in the water before hitting
the walls. Their color indicates they arrived much later than
the green and yellow hits of the
This shows the
hits are projected onto a sphere whose center is at the
fisheye. The sphere is then opened up so the ring is in the "forward"
hemisphere. The green ring is the outer edge of an ideal 41 degree
Cherenkov cone. A perfect track in a perfect world would have all
the hits be the same color and just inside of the green circle.
Note that the "backward"
hemisphere is empty for this single-track event. It represents only
one-half of what would be seen in a true proton decay event.
Protons are essentially at rest in
the water and their decay must result in at least two new particles
going in opposite directions. We use this feature to distinguish
proton decays from neutrino interactions in the water.
This is illustrated below.
The initial version of the IMB detector was designed
to look for one of the simplest modes:
a proton decaying into a positron (e+) and a neutral pion
(pi0). These particles would give rise to two Cherenkov cones
going in opposite directions.
The event at left is an artificial ("monte
carlo") event which gives an example of what a real proton
decay into e+ and pi0 would look like on the cylinder
plot. The two rings are not very well-defined here because the electromagnetic
showers produced by the e+ and pi0 contain several electrons and
positrons with scattered directions.
The two red A
points are where the computer estimated the centers of the
two showers were pointed. The calculated angle between the shower
directions was 160 deg., which is near the 180 deg. angle at which
they were generated.
A real event which is similar to this one
is seen in the cylinder plot on the left below.
The three pictures below are three views
of an event we recorded in our first few months of running
in the fall of 1982. It looks quite similar to the above simulated event,
so naturally we were quite
excited when we first saw it. On closer inspection, however, the event
has three properties
that don't match proton decay. Any one of these is sufficient to
These properties are explained below the pictures.
This cylinder plot shows one fatal
property of this event:
It has too much total energy.
Qualitatively one can see many more total slashes than on the plot
above it. Quantitatively it's total energy is estimated to be 1230
MeV, too far from the 938 MeV value expected from a proton decay.
Secondly, it's clear from this sphere
plot that the two showers are not 180 deg apart. In fact the measured
angle between A and
B on the cylinder plot is only 135 deg: too far
from the expected 180 deg of a proton decay at rest.
This particular event has a third
The IMB detector had a "T2 time
scale", designed to capture the signal from a muon decaying
into an electron a few microseconds after the main event.This would
indicate that one of the tracks in the main event was a muon. A
picture of the T2 time scale above clearly shows a signal of an
electron in the vicinity of the backward-hemisphere track on the
sphere plot, so this event can not be due to an (e+,pi0) decay mode.
It could perhaps be a (mu+,pi0) mode but then the energy and angle
requirements would still rule it out.
if the above event is not a proton decay, what is it?
The above event is one of 69 that
were found inside the IMB detector in its first 80 live days of
This event rate agreed (within a factor of two) with expectations
due to neutrino interactions in the water.
The neutrinos are produced by cosmic rays hitting the atmosphere
all around the Earth.
Billions of them pass through the detector every second and from
About once per day a neutrino will interact in the water producing
some charged particles which leave telltale Cherenkov rings.
Of the first 69 events only three
vaguely resembled the hypothesized proton decay into (e+,pi0).
Upon closer examination all of them, including the one pictured
above, were eliminated.
With no viable candidates we were able to determine that the lifetime
of the proton,
for this decay mode, was at least 6.5 X 10^31 years.
This result was published in the
first IMB paper in 1983. The title page is shown below.
By this time the collaboration had grown to 29 members,
including 11 graduate students who contributed greatly to the
success of the project.
For more pictures click
and search for "Vander
Go to top of:
This page (3) | <urn:uuid:efda360a-3ee1-4fc5-ba53-f71c3a8935d0> | 3.890625 | 1,801 | Knowledge Article | Science & Tech. | 60.22252 |
Science subject and location tags
Articles, documents and multimedia from ABC Science
Thursday, 7 July 2011
One of the most violent weather events in the Solar System is still enthralling astronomers now.
Wednesday, 6 July 2011
StarStuff Podcast The launch of Space Shuttle Atlantis is the last for the space shuttle program. StarStuff looks back at one of America's most successful space programs, talking with astronauts Andy Thomas and Paul Scully-Power, the only Australians to have flown aboard the shuttles.
Tuesday, 5 July 2011
Quiz The space shuttle is about launch into space for the very last time. How much do you know about this space-age icon?
Monday, 4 July 2011
Final countdown The space shuttle Atlantis is poised to launch on the final flight of the 30-year program.
Thursday, 30 June 2011
StarStuff Podcast House-sized asteroid soars 8000 kilometres above Earth. Plus: Voyager 1 travels beyond solar system; and saltwater oceans found beneath surface of Saturn's moon, Enceladus.
Thursday, 23 June 2011
Saturn's strange ice moon Enceladus may have a salty ocean lurking beneath its frozen surface.
Wednesday, 22 June 2011
StarStuff Podcast Have scientists discovered a new comet in the inner solar system? Plus: astronomers observe sun torn apart by black hole; and final space shuttle flight readies for launch.
Monday, 20 June 2011
Mercury's origins may be very different from its sister planets, including Earth, based on early findings that show surprisingly rich deposits of sulfur on the planet's surface.
Friday, 17 June 2011
Close-up images of a peanut-shaped comet have found its surface is be unusually active, spraying vast amounts of ice and water into space.
Wednesday, 15 June 2011
StarStuff Podcast CERN physicists use the Large Hadron Collider to generate temperatures 100,000-times hotter than the Sun. Plus: building blocks of life spread throughout space; and scientists discover new type of supernova.
Wednesday, 8 June 2011
StarStuff Podcast Jupiter and Saturn help shape our solar system. Plus: Crystal rain falls like 'green glitter' on growing star; and space shuttle Endeavour lands for last time.
Wednesday, 1 June 2011
StarStuff Podcast US mission plans to land on an asteroid that might hit the Earth late next century. Plus a new record for the most distant object in the universe; and Orion to take astronauts beyond the International Space Station.
Wednesday, 25 May 2011
StarStuff Podcast Dark energy is real and causing space-time to expand. Plus: lonely planets may be missing their stars; and NASA spacecraft targets first asteroid.
Wednesday, 18 May 2011
StarStuff Podcast Super-hot magma beneath surface of Jupiter moon Io. Plus: NASA seeks to sail seas of Saturn satellite, Titan; and space shuttle Endeavour lifts off for its final mission.
Wednesday, 11 May 2011
StarStuff Podcast Primordial black holes may be older than Big Bang. Plus: Titanic stellar impacts generate Saturn moon's atmosphere; and antimatter hydrogen may fall up. | <urn:uuid:115148c2-1d63-4398-80b9-b6c0c3dde107> | 2.953125 | 642 | Content Listing | Science & Tech. | 50.199776 |
On 10/29/07, Tom Phoenix <tom@xxxxxxxxxxxxxx> wrote:
> An array is the kind of variable which holds
> a list; a list is the kind of data which is stored in an array. You
> can use the list contained in an array, and you can store a list into
> an array. But the array is the container, and the list is the
I do agree with this statement,thanks Tom.
may I ask an OT question, I think perl's list is the same as python's
tuple.Both have the same characteristics but tuple is a real variable. | <urn:uuid:fa2e98c7-f692-41d2-b8b3-43be40e0da84> | 2.875 | 130 | Comment Section | Software Dev. | 78.210727 |
Nitrogen fixation refers to the conversion of atmospheric nitrogen gas (N 2 ) into a form usable by plants and other organisms. Nitrogen fixation is conducted by a variety of bacteria, both as free-living organisms and in symbiotic association with plants. Because it is the principal source of the nitrogen in the soil, nitrogen that plants need to grow, nitrogen fixation is one of the most important biochemical processes on Earth. Even modern agricultural systems depend on nitrogen fixation by alfalfa, clover, and other legumes to supplement chemical nitrogen fertilizers.
Living organisms need nitrogen because it is a part of the amino acids that make up proteins , and the nucleic acids that make up DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Nitrogen within living organisms is eventually decomposed and converted to atmospheric nitrogen (N 2 ). This form, however, is highly stable and unreactive chemically, and is therefore not available for use by most organisms. Some species of bacteria, though, can convert N 2 into NH 3 (ammonia) or other usable forms of nitrogen. These nitrogen-fixing bacteria include species of the genera Rhizobium, Anabaena, Azotobacter, and Clostridium, as well as others.
Each of the nitrogen-fixing bacteria employs the same enzyme , nitrogenase. The nitrogenase enzyme is shaped something like a butterfly, and contains an atom of molybdenum at its core that is crucial for the reaction. Soils deficient in molybdenum cannot sustain effective nitrogen fixation, and monitoring soil for this element is important to ensure maximum fixation in managed fields or pastures.
Nitrogenase requires a large amount of energy to convert N 2 to NH 3 . Free-living bacteria must obtain the nutrients for supplying this energy themselves. Other bacteria have developed symbiotic associations with plants to provide them with sugars, supplying both a source of energy and a source of carbon for the bacterium's own synthetic reactions. The bacteria, in turn, supply the plant with some of the fixed nitrogen. For instance, the nitrogen-fixing Anabaena lives symbiotically with a water fern, Azolla. Azolla is grown in rice paddies early in the season. As the rice grows above the water surface, it shades out the fern, which dies, releasing the stored nitrogen. In this way, the paddy is fertilized without application of chemical fertilizers.
The bacterial genera Rhizobium and Bradyrhizobium have developed a large number of symbioses with members of the Fabaceae (legume) family. Fabaceae includes alfalfa, clover, beans and peas of all kinds, mesquites, acacias, and dozens of other species both domesticated and wild. The roots of the host plant become infected with the bacteria as seedlings, and respond by surrounding the bacteria with root hairs. The relationship between a particular host species and a particular bacterium is highly specific,
The plant eventually develops a specialized structure known as a nodule, while the bacteria inside grow into enlarged forms known as bacteroids. The oxygen concentration inside the nodule must be closely regulated, since oxygen inhibits nitrogenase. This regulation is aided by the presence of leghemoglobin, an oxygen-binding protein similar to hemoglobin . The heme (oxygen-binding) portion is produced by the bacterium, while the globin (protein) portion is produced by the host plant, again illustrating the closeness of the symbiotic relationship.
Raven, Peter H., Ray F. Evert, and Susan E. Eichhorn. Biology of Plants, 6th ed. New York: W. H. Freeman and Company, 1999. | <urn:uuid:d1431faf-af4e-4d26-ae0c-06e9ff71f3b8> | 4.15625 | 771 | Knowledge Article | Science & Tech. | 30.139451 |
Earthquakes can have a silver -- or rather golden -- lining. Some six miles underground, water can contain trace amounts of gold and silica. When an earthquake occurs, voids along a geological fault widen suddenly, pressure plummets, and the water held inside turns to steam. Meanwhile, the gold and silica in that water end up on local surfaces, scientists in Australia suggest.
It's not much gold, but it can build up over time, LiveScience reports. The phenomenon can cause gold to "precipitate almost immediately," researchers say, per AFP. And even the smallest earthquakes may be capable of initiating the process.
"Given that small-magnitude earthquakes are exceptionally frequent in fault systems, this process may be the primary driver for the formation of economic gold deposits," says one of the researchers.
The theory could also explain why gold is often associated with quartz, as in the 19th-century U.S. gold rush.
Copyright 2013 USATODAY.com
Read the original story: Eureka! Earthquakes give us gold | <urn:uuid:d7073da1-0cbf-4f48-ac68-be547b355521> | 3.828125 | 221 | Truncated | Science & Tech. | 46.188216 |
In the great stellated dodecahedron and the small stellated dodecahedron, the faces are pentagrams. It is easier to see which parts of the exterior belong to which pentagram if you look at a six-colored model of the great stellated dodecahedron and a six-colored model of the small stellated dodecahedron. The center of each pentagram is hidden inside the polyhedron. These two polyhedra were described by Johannes Kepler in 1619, and he deserves credit for first understanding them mathematically, but a 16th century drawing by Jamnitzer is very similar to the former and a 15th century mosaic attributed to Uccello illustrates the latter.
two polyhedra have three and five pentagrams, respectively, meeting at
each vertex. Because the faces intersect each other, parts of each face
are hidden by other faces, and you need to see
that the visible portions of the faces are not the complete faces.
In the great icosahedron and great dodecahedron (described by Louis Poinsot in 1809, although Jamnitzer made a picture of the great dodecahedron in 1568) the faces (20 triangles and 12 pentagons, respectively) which meet at each vertex "go around twice" and intersect each other, in a manner which is the 3D analog to what happens in 2D with a pentagram.
If you slice the polyhedron near a vertex, you'll see a pentagram cross section as the vertex figure. For example, this cutaway view of the great dodecahedron shows how the five pentagons which meet at a vertex pass through each other in the manner of a pentagram. Study the virtual models to see this. To emphasize that these polyhedra are made of large convex faces, it helps to look at a five-color model of the great icosahedron and a six-color model of the great dodecahedron.
Together, the Platonic solids and these Kepler-Poinsot polyhedra form the set of 9 regular polyhedra. Cauchy first proved that no other polyhedra can exist with identical regular faces and identical regular vertices.
Here are some relationships you should observe:
Exercise: Which of these four polyhedra have a dodecahedron and which an icosahedron as their innermost region? Imagine how the planes intersect, then travel inside to find out. (Note: be sure to find the centermost region.)
Answer: Find out when you read about stellations. | <urn:uuid:ed0f3194-cd54-4918-a656-d9af5c0fabdb> | 3.859375 | 542 | Tutorial | Science & Tech. | 35.206238 |
Unit 3: Gravity
Although by far the weakest of the known forces in nature, gravity pervades the universe and played an essential role in the evolution of the universe to its current state. Newton's law of universal gravitation and its elegant successor, Einstein's theory of general relativity, represent milestones in the history of science and provide the best descriptions we have of gravity. General relativity is founded on the principle of equivalence of gravity and acceleration; an inescapable consequence is that gravity governs the very geometry of space and time. This property of gravity distinguishes it from the other forces and makes attempts to unify all of the forces into a "theory of everything" exceedingly difficult. How well do we really understand gravity? Do the same laws of gravity apply to objects on the opposite sides of the universe as to particles in the microscopic quantum world? Current research is attempting to improve the precision to which the laws of gravity have been tested and to expand the realm over which tests of gravity have been made. Gravitational waves, predicted by general relativity, are expected to be observed in the near future. This unit will review what we know about gravity and describe many of the directions that research in gravitation is following. | <urn:uuid:b3e20afc-7d44-4e54-9a28-72270955b9f4> | 4.0625 | 243 | Knowledge Article | Science & Tech. | 22.43801 |
The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Natural Climate Variability on Decade-to-Century Time Scales
will be presented. For information on snowfall and its long-term variability across the North American continent, the paper later in this section by Groisman and Easterling (1995) is recommended.
IN SITU OBSERVATIONS
In situ snow-cover data are gathered mainly over land. Only a few short-term studies have measured snow on sea ice or ice sheets (e.g., Hanson, 1980). Most observations on land are made on a once-per-day basis. The general practice is to record the average depth of snow lying on level, open ground that has a natural surface cover. At primary stations, the water equivalent of the snowpack may also be measured. In some regions, snow courses have been established where snow depth, water equivalent, and perhaps other pack properties are measured along prescribed transects across the landscape. Observations are often made only once per month, and the number of courses is extremely limited in North America. More frequent and abundant course data are gathered in the Commonwealth of Independent States, and currently this information is being recovered through a cooperative effort between the U.S. National Snow and Ice Data Center (NSIDC) at the University of Colorado and A. Krenke of the Russian Academy of Sciences.
Current station observations of snow cover are of a sufficient density for climatological study in the lower elevations of the middle latitudes. Elsewhere, while data of a high quality are gathered at a number of locations (Barry, 1983), the spatial and temporal coverage of the information is often inadequate for climate study. There is no hemispheric snow-cover product based entirely on station reports. The U.S. Air Force global snow-depth product depends heavily on surface-based observations as input into a numerical model that creates daily charts with global coverage, but it must rely on extrapolations and climatology in data-sparse regions (Hall, 1986; Armstrong and Hardman, 1991). There have been a number of regional snow-cover products over the years that are based on station data. Of greatest longevity are the Weekly Weather and Crop Bulletin charts, which have been produced since 1935. These, and the daily NOAA charts, are produced for the conterminous United States mainly from first-order station observations. Therefore, neither has a particularly high resolution, and observations may be influenced by urban heat-island effects.
In a number of countries, there are numerous stations with relatively complete records of snow extending back 50 years or more (Barry and Armstrong, 1987). Until recently, most data have remained unverified and disorganized (Robinson, 1989). As a result, few studies have dealt with long-term trends or low-frequency fluctuations of snow over even small regions (e.g., Arakawa, 1957; Manley, 1969; Jackson, 1978; Pfister, 1985). Through the cooperative efforts of a number of scientists and data centers, this situation has begun to be rectified. Examples include the exchange of data through the US/USSR Bi-Lateral Environmental Data Exchange Agreement and between the Lanzhou Institute of Glaciology and Geocryology and both Rutgers University and the NSIDC. These and other data are in the process of being quality controlled, and routines to fill in gaps in snow-cover records are being developed (Hughes and Robinson, 1993; Robinson, 1993a). Clearly, there is a need to continue efforts to identify, assimilate, in some cases digitize, and in all cases validate station and snow-course observations from around the world. These data must also must be accompanied by accurate and complete metadata.
Lengthy in situ records continue to be analyzed for individual stations, and data from networks of stations have begun to be studied on a regional level. For example, marked year-to-year variability in snow-cover duration is recognized over the course of this century at Denison, Iowa (Figure 1). Snow at least 7.5 cm deep has covered the area for as much as 80 percent of the winter, but in a number of years no or only a few days have had a cover this deep. Overall, the duration of winter and spring cover was at a maximum in the 1970s, and fall cover peaked in the 1950s. Other periods of more frequent winter cover include the 1910s and the late 1930s to early 1940s. The 1920s, middle 1940s, and late 1950s to early 1960s were periods with less abundant winter cover. Missing data around 1950 prohibit a direct assessment of winter cover at Denison, but adjacent stations suggest cover was scarce at this time. All three seasons show a greater abundance of snow-cover days in the past 40 years than in the first half of the century.
Efforts are under way to develop gridded snow files for a large portion of the central United States, using data from several hundred stations. Raw and filtered winter records from four of these stations are shown in Figure 2. They are for days with snow cover =7.5 cm, and all indicate long-term fluctuations on the order of one to several decades. The Nebraska and Kansas stations show maximum durations during the past several decades, with a similar early maximum at Oshkosh, Nebraska, in the 1910s and early 1940s. Late 1920s, early 1950s, and 1970s maxima were observed at Dupree, South Dakota, the latter two ending abruptly shortly thereafter. The North Dakota station had maximum winter snow cover in the 1930s, around 1950, and in the late 1970s. The range in filtered values over the period of record was approximately two weeks in Kansas and Nebraska and seven weeks in South Dakota and North Dakota.
Snow extent is monitored using data recorded in short-wave (visible and near-infrared) and microwave wave- | <urn:uuid:55bcd30c-3d27-4153-87fe-4dd66f2dc4e3> | 3.046875 | 1,244 | Knowledge Article | Science & Tech. | 40.699545 |
|Biologist Barry Sinervo holds a pregnant mesquite lizard.
Sinervo led an international team of biologists who conducted the study, published in the May 14 issue of Science. The researchers surveyed lizard populations, studied the effects of rising temperatures on lizards, and used their findings to develop a predictive model of extinction risk. Their model accurately predicted specific locations on five continents (North and South America, Europe, Africa and Australia) where previously studied lizard populations already have gone extinct locally.
"We did a lot of work on the ground to validate the model and show that the extinctions are the result of climate change," Sinervo said. "None of these are due to habitat loss. These sites are not disturbed in any way, and most of them are in national parks or other protected areas."
As local populations continue to disappear, species extinctions will follow, he said. "Most of these species currently registering local extinctions will be completely extinct by 2080, unless we change and limit the carbon dioxide production that is driving global warming," he said.
The disappearance of lizard populations is likely to have repercussions up and down the food chain. Lizards are important prey for many birds, snakes and other animals, and they are important predators of insects. "We could see other species collapse on the upper end of the food chain, and a release on insect populations," Sinervo said.
Biologists also have documented dramatic declines and extinctions of amphibian populations around the world, leading to estimates that one-third of amphibian species are at risk of extinction. But Sinervo noted that amphibian extinctions are attributed mostly to the spread of a deadly fungal disease, with a possible indirect link to environmental factors such as global warming.
"Our research shows that the ongoing extinctions of lizards are directly due to climate warming from 1975 to the present," he said.
A herpetologist known for his research on evolutionary patterns in lizard populations, Sinervo began studying extinctions after noticing a disturbing trend in recent years. When he and colleague Donald Miles of Ohio University went looking for populations that other researchers had studied in the 1980s and 90s, they found that many had disappeared. This happened first in France, where they worked with French researchers Benoit Heulin and Jean Clobert, and later in Mexico, where they worked with Jack Sites of Brigham Young University and Mexican herpetologist Fausto Méndez de la Cruz.
In Mexico, Sinervo, Méndez de la Cruz, Miles, and their students resurveyed 48 species of spiny lizards (Sceloporus) at 200 sites where the lizards had been studied between 1975 and 1995. They found that 12 percent of the local populations had gone extinct.
To investigate the link between these extinctions and temperature, the researchers went to a site on the Yucatan Peninsula where Méndez de la Cruz's student Norberto Martínez had observed populations of the blue spiny lizard (Sceloporus serrifer) declining over the course of his Ph.D. research. After building a device that would mimic the body temperature of a lizard basking in the sun and record the temperatures on a microchip, they set the devices in sun-exposed sites for four months in locations with and without surviving populations of blue spiny lizards.
"The results were clear," Sinervo said. "These lizards need to bask in the sun to warm up, but if it gets too hot they have to retreat into the shade, and then they can't hunt for food. At the extinct sites in the Yucatan, we found that the hours per day they could be out foraging had collapsed. They would barely have been able to emerge to bask before having to retreat."
Sinervo used these findings to develop a model of extinction risk based on maximum air temperatures, the physiologically active body temperature of each species, and the hours in which a lizard's activity would be restricted by temperature. In comparing the model predictions with observations in Mexico, the only differences were in cases where a population was eliminated sooner than expected due to competition from a species that expanded its range because it was adapted to higher temperatures.
The researchers found that climate change is occurring too rapidly for lizards to compensate with physiological adaptations to higher body temperatures. "We thought we'd see evolution occurring in response to climate change, but instead we're seeing extinctions. Beyond a certain point, the lizards can't adapt," Sinervo said. "We're predicting 40 percent of local populations will go extinct, and that will translate into roughly 20 percent of species going extinct by 2080."
In extending the extinction model globally, the researchers used available data on lizard body temperatures and historical data on the geographic distributions of different species to determine how many hours of activity restriction could be sustained by lizards in each of 34 families. (Family is a taxonomic ranking that includes many related species; examples include the gecko, iguana, and monitor lizard families.)
From climatologists, the researchers were able to get extremely detailed maps of maximum daily air temperatures over the entire planet in the past and present, as well as projections for the future based on climate models. To validate the extinction risk model, the U.S., French, and Mexican teams enlisted the help of colleagues around the world to provide data on local extinctions, working with researchers in Argentina, Brazil, Chile, Peru, South Africa, and Australia. Sinervo and Miles also conducted "virtual field expeditions" using Google Scholar and Google Earth.
"We would search on registered local extinctions and map them," Sinervo said. "Miles immediately found a massive wave of extinctions sweeping Madagascar, which the model had already targeted as an ecological disaster in the making."
The climate projections used to model extinction risks assume a continuation of current trends in carbon dioxide emissions from human activities. Many of the extinctions projected for 2080 could be avoided if global efforts to reduce emissions are successful, but the scenario for 2050 is probably inevitable, Sinervo said. "The extinctions are happening really fast. I'm watching new populations go extinct every year," he said.
Funding for this study included grants from the National Geographic Society, National Science Foundation, UC Mexus, UC Santa Cruz (Committee on Research grant), the French National Center for Scientific Research (CNRS), the Mexican National Council on Science and Technology (CONACYT), the Australian Research Council, and research councils in Argentina (CONICET) and Spain (SMSI). | <urn:uuid:c4fb81d6-6826-49cd-b23f-3c6e49d6d3a6> | 3.828125 | 1,349 | Knowledge Article | Science & Tech. | 29.864171 |
Lenticular clouds above mountains surrounding Death Valley. (Photo credit: Eastcott Momatiuk/Thinkstock)
Few things are more captivating to meteorologists than seeing a stunning cloud right outside the front door. Particularly, one of these ten spectacular clouds.
Lenticular clouds are most common near or downwind of mountain ranges. Their "flying saucer" appearance is owed to the forced ascent of stable air over mountain ranges.
By stable air, we mean air that when forced to rise, does not accelerate upward (as in, say, cumulonimbus clouds) but rather comes back down, as it turns colder, or more dense, than the surrounding air.
The lenticular cloud denotes the upward part, or crest, of the mountain wave of air. You can't see the downward part, or trough, of the wave, since air moving down dries out. As long as the ambient weather conditions (winds, humidity) are unchanged, the cloud won't move, appearing to hover near the mountain range. | <urn:uuid:cd55c2f5-ef70-46b2-95b9-3e647428fc99> | 3.234375 | 213 | Listicle | Science & Tech. | 50.173799 |
Congo clawless otters are found in the lower Congo basin, which lies between southeastern Nigeria and western Uganda. (Estes, 1991; Haltenorth and Diller, 1980; Kingdon, 1982; Nowak, 1999; Estes, 1991; Haltenorth and Diller, 1980; Kingdon, 1982; Nowak, 1999)
Congo clawless otters reside exclusively in the small swamps, ponds, and streams of heavy rainforests. Due to their amphibious lifestyle, these otters are both excellent swimmers and skilled explorers of the shores (Kingdon, 1982). Their hair type, reduced vibrissae, and rather generalized dental morphology suggest that they may be more terrestrial than other otter species (Nowak, 1999). (Kingdon, 1982; Nowak, 1999)
Aonyx capensis congica is a large, powerfully built otter, though it is more slender in the neck and back than other populations of Aonyx capensis. Head and body length ranges between 78 and 97 cm, with the tail adding an additional 40 to 59 cm to the total length. Weights range from 15 to 25 kg in adult animals.
These otters have a dark, chestnut-brown coat with some silver frosting on the head and neck, contrasted by a white chest, nose and ears. A distinctive black patch is located between the eyes and nostrils (Kingdon, 1982). Aonyx capensis congica young resemble the adults except for a greater frosting of the coat. Unlike many other otter species, A. capensis congica has no claws, no webbing in the manus, and webbing only halfway down the digits in the pes. All are adaptations to improve dexterity and tactile sensitivity for foraging in the muddy waters of the lower Congo basin. The less specialized dentition of A. capensis congica, when compared to the broader species, A. capensis, serves as a distinguishing characteristic and suggests a broader carnivorous diet than other populations (Haltenorth and Diller, 1980). (Haltenorth and Diller, 1980; Kingdon, 1982)
Very little has been recorded about the mating habits of Congo clawless otters. They remain enigmatic as their elusive nature and remote range have prevented many of their behaviors from being described (Estes, 1991). One could infer that the mating system is similar to other African otter species, where there is a short-lived monogamy followed by a return to a more solitary lifestyle (Chanin, 1985). (Chanin, 1985; Estes, 1991)
Nothing is known with certainty about the reproductive behavior of A. capensis congica. It has been suggested that the gestation period is around two months, that an average of two to three young are born per litter, and that young do not reach sexual maturity until about one year of age (Nowak, 1999). Although it is not known whether the breeding is seasonal or occurs throughout the year, births do seem to peak in the dry season in other Aonyx capensis populations, and it is predicted that A. capensis congica would be similar (Estes, 1991). (Estes, 1991; Nowak, 1999)
Despite a paucity of information on the development and reproduction of these otters, we can reasonably infer that they are similar to other members of the genus Aonyx. Aonyx cinerea has an estruous cycle that lasts between 22.4 and 30 days, and an estrus of 3 days. Because the gestation period is between 60 and 64 days, they can produce two litters per year. The young are altricial, and do not open their eyes until the age of 40 days. Young are able to swim by the age of 9 weeks, and eat solid foods after 80 days. (Nowak, 1999)
Much of the parental behavior in Congo clawless otters is unknown. The mother is the primary care giver, but it is unclear to what degree the male is involved in rearing young (Nowak, 1999). Although we may infer that the mother provides young with milk, shelter, and grooming during their period of dependency, the duration of care is a mystery. Further, there is very little documentation on other members of the genus; observed males of the same subfamily, Lutrinae, show varying degrees of care. Though often solitary creatures, Congo clawless otters have been observed foraging as family parties. However, it is hypothesized that these associations are transient and based more on territory sharing and overlapping rather than a post-independence affinity for their family members (Haltenorth and Diller, 1980). (Haltenorth and Diller, 1980; Nowak, 1999)
Lifespan range in A. capensis congica is unknown. Captive specimens of the larger species, A. capensis, and the related species, A. cinerea, have lived as long as 14 and 16 years respectively (Nowak, 1999). (Nowak, 1999)
Congo clawless otters are mostly nocturnal, but have been observed in undisturbed swamp lands during the daytime. Though mostly solitary, family groups have also been observed along the rivers of Cameroon (Kingdon, 1982). The social organization of A. capensis congica is not well understood. In other A. capensis populations, individuals defend territories of around twelve square kilometers that often overlap with three or more other adult males (Nowak, 1999). (Kingdon, 1982; Nowak, 1999)
No form of communication has been specifically documented for A. capensis congica. Clawless otters, in general, communicate vocally with chirps, squeals, and purring noises when expressing affection or play. Often growls, snarls, and a screaming wail are signs of displeasure or apprehension. Clawless otters also use strong olfactory cues to communicate. They musk their coats and produce a sticky feces, capable of clinging to vertical surfaces, to mark the boundaries of their territory. The visual aspects of communication, including body language, are mostly undescribed (Estes, 1991). Tactile communication is undoubtedly of some importance in reproduction, especially between mates and between a mother and her offspring. (Estes, 1991)
Aonyx capensis congica is known to have a broad carnivorous diet, consisting of crabs, mollusks, fish, frogs, and other small vertebrates and invertebrates found in the shallow rivers and muddy shores of the Congo river basin. Its streamlined, powerful body propels it after the aquatic prey of rivers and ponds. Its specially adapted fingers are sensitive and dexterous, well suited for overturning stones, grasping prey, and sifting through the muddy shores of streams and swamps for invertebrates (Kingdon, 1982). Aonyx capensis congica has also been observed hunting in the tangled reeds and shoots of riverside vegetation, actively stalking small terrestrial vertebrates from cover (Haltenorth and Diller, 1980). (Haltenorth and Diller, 1980; Kingdon, 1982)
The dark chestnut coat of A. capensis congica acts as a form of camouflage within the muddy swamps and rivers of the Congo basin. The coloration may protect A. capensis congica from predation by the crocodiles, pythons, eagles, and leopards in this habitat (Kingdon, 1982). Although there is no documentation of predation on Congo clawless otters, other otter species are taken by large snakes, crocodilians, large cats, and birds of prey (Berry, 2000). It is reasonable to assume that similar predators take A. capensis congica.
Although it is not illustrated or described for A. capensis congica, the arched posture, snarled facial expressions, and harsh vocalizations of a defensive otter are commonly observed in the genus Aonyx (Estes, 1991). (Berry, 2000; Estes, 1991; Kingdon, 1982)
Within the rainforest ecosystem, A. capensis congica acts as a predator, preying on crustaceans, fish, frogs, and other small vertebrates and invertebrates. It is also a possible prey animal for pythons, leopards, eagles, and crocodiles (Kingdon, 1982). (Kingdon, 1982)
If captured when young, their relatives, Aonyx cinerea have proven intelligent pets and have been trained to catch fish for Malay fishermen. Aonyx capensis congica has been commercially hunted for its beautiful coat as well. Though the fur quality is considered not as high as other otter species. (Nowak, 1999)
Aonyx capensis congica has no known negative effects on the economy. However, if provoked, clawless otters have been known to sever fingers from the hands of humans with their bite. They have also attacked and drowned dogs that tread too closely to them (Estes, 1991). (Estes, 1991)
The most likely causes for the endangered status of A. capensis congica are habitat loss and pollution due to development in the Congo basin as well as chronic over-harvesting for fur (Nowak, 1999). (Nowak, 1999)
Much of the natural history of A. capensis congica remains a mystery at this point. Most of what is currently help to be true of these animals has been constructed from fragmentary field observations and assumptions based on other populations of A. capensis, which are also poorly understood. Aonyx capensis congica was previously considered a species, A. congicus, but range overlap and similarities with A. capensis resulted in their being considered a population of A. capensis.
Tanya Dewey (editor), Animal Diversity Web.
Barbara Lundrigan (editor, instructor), Michigan State University, Daniel MacArthur (author), Michigan State University.
Nancy Shefferly (editor), Animal Diversity Web.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
uses sound to communicate
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
union of egg and spermatozoan
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
eats mollusks, members of Phylum Mollusca
Having one mate at a time.
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
chemicals released into air or water that are detected by and responded to by other animals of the same species
an animal that mainly eats fish
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
Berry, K. 2000. "Animal Diversity Web" (On-line). Accessed April 09, 2005 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Lontra_longicaudis.html.
Chanin, P. 1985. The natural history of otters. London: Croom Helm.
Estes, R. 1991. The behavior guide to African mammals : including hoofed mammals, carnivores, primates / Richard Despard Estes ; drawings by Daniel Otte ; foreword by E.O. Wilson. Berkeley: University of California Press.
Haltenorth, T., H. Diller. 1980. A field guide to the mammals of Africa, including Madagascar / Theodor Haltenorth, Helmut Diller ; translated by Robert W. Hayman. London: Willliam Collins Sons and Co Ltd.
Harris, C. 1968. Otters: a study of the recent Lutrinae. London: Weidenfeld & Nicolson.
Kingdon, J. 1982. East African Mammals: an atlas of evolution in Africa. London, New York: Academic Press.
Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press. | <urn:uuid:d76b1f6e-d25d-4975-b64a-06a28d4188c2> | 3.46875 | 2,965 | Knowledge Article | Science & Tech. | 40.707536 |
Rotate an image by 90-degree increments
#include <img/img.h> int img_rotate_ortho( const img_t *src, img_t *dst, img_fixed_t angle );
- The image to rotate
- The address of an img_t describing the destination. If you don't specify width or height (or both) in the dst then this function will calculate the missing dimension(s) based on the src image, taking into account the rotation. If you do specify either width or height (or both), the image is clipped as necessary; unused data remains untouched.
- A 16.16 fixed point representation of the angle (in radians). There are 3 defines provided for convenience:
- IMG_ANGLE_90CW — 90 degrees clockwise (to the right)
- IMG_ANGLE_180 — 180 degrees
- IMG_ANGLE_90CCW — 90 degrees counter-clockwise (to the left)
Use the -l img option to qcc to link against this library.
This function rotates the src image by 90-degree increments. The rotation is not a true rotation in that the image is not rotated about a fixed point. Rather, the image itself is rotated and the new origin of the image becomes the upper-left corner of the rotated image.
The formats of src and dst don't have to be the same; if they are different, the data is converted. A palette-based dst format is only supported if the src data also is palette-based.
- Some fields of src are missing (that is, not marked as valid in flags)
- Unsupported format conversion or angle
- Insufficient memory (the function requires a small amount of working memory) | <urn:uuid:01a3a9bf-2381-46ca-aaa8-878b77771247> | 2.921875 | 371 | Documentation | Software Dev. | 49.870136 |
MSI-SuperDARN Radars | Spacecraft Shielding | Ionospheric Convection | GICs | Publications
Scientists at four institutions (Virginia Tech, Dartmouth College, the University of Alaska Fairbanks, and the Johns Hopkins University Applied Physics Laboratory) will build eight (8) SuperDARN-style HF radars at middle geomagnetic latitudes across the U.S. and in the Azores between 2009 and 2012. This collaborative effort was made possible by a generous grant from the National Science Foundation (NSF) through the Mid-Sized Infrastructure (MSI) program.
The MSI SuperDARN radars, together with existing mid-latitude SuperDARN radars, will provide unprecedented measurements of the drifting plasma with coverage that spans over 12 hours in local time and extends from ~50 degrees magnetic latitude all the way to the pole. The array of radars, coupled with the existing SuperDARN network, will provide exciting new measurements of ionospheric plasma irregularities in regions of the plasmaspheric boundary layer and during magnetic storms.
Spacecraft Radiation Shielding
Manned missions to planets such as Mars require extended missions that will expose astronauts to harmful radiation in the form of energetic particles from solar and galatic sources. Traditional methods for protecting spacecraft and occupants from these forms of radiation involve some configuration of a massive material shield to absorb the energy of incoming particles. For the high energy galactic cosmic rays (GCRs) that astronauts will be exposed to, these so-called passive shields are too massive to be practical and will likely produce showers of secondary radiation that could be more harmful than the GCRs themselves.
Active shields which rely on magnetic (or electric) fields to deflect energetic particles offer a potential solution to the problem. Designing a magnetic shield that is strong enough to deflect GCR particles but weak enough to not harm astronauts is a challenge. Investigating possible solutions involves a combination of electromagnetic theory, numerical analysis, engineering practicality, and an astronaut's sense of exploration.
Ionospheric Electric FieldsA combination of reconnection and viscous processes occurring at the magnetopause and in the magnetotail are responsible for creating large-scale electric fields. These fields map down geomagnetic field lines into the high-latitude ionosphere where they cause the plasma to 'E x B' drift. By measuring the motion of this ionospheric plasma it is, therefore, possible to infer a great deal about the magnetospheric processes that are responsible for the convection.
Scientists from all over the world are involved in a cooperative program which operate HF radars for the purpose of measuring the ionospheric plasma drift (or equivalently, the ionospheric electric field.)
Geomagnetically Induced Currents (GICs)Large-scale currents flowing overhead in the ionosphere induce electric and magnetic fields on the surface of the Earth. So-called Geomagnetically Induced Currents (GICs) can in turn be induced in technologically networks located underneath these currents, such as railroads, power transmission lines, and pipelines. During electromagnetic storm periods caused by the Sun these GICs can be large, often exceeding several hundred Amperes, and cause catastrophic consequences to the system in which they flow.
Scientists at Dartmouth are attempting to predict the occurence of GICs using physics-based models of the global magnetosphere, ionosphere, and Earth conductivity together with input from a satellite located in the upstream solar wind. The electric (and magentic) field at the surface of the Earth over North America will be determined with 30-90 minutes warning, allowing an advance warning of GICs to be calculated for specific conducting networks.
More details can be found on the Darmtouth College GIC Page
- Shepherd, S. G., and J. P. G. Shepherd, Toroidal magnetic spacecraft shield used to deflect energetic charged particles, JOURNAL OF SPACECRAFT AND ROCKETS, VOL. 46, doi:10.2514/1.37727, 2009.
- Shepherd, S. G., and B. T. Kress, Stormer theory applied to magnetic spacecraft shielding, SPACE WEATHER, VOL. 5, NO. 4, S04001, doi:10.1029/2006SW000273, 2007.
- Shepherd, S. G., and B. T. Kress, Comment on "Applications for Deployed High Temperature Superconducting Coils in Spacecraft Engineering: A Review and Analysis" by J. C. Cocks et al., JOURNAL OF THE BRITISH INTERPLANETARY SOCIETY, VOL. 60, PAGES 129--132, 2007.
- Shepherd, S. G., Polar Cap Potential Saturation: Observations, Theory, and Modeling, JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS, VOL. 69, doi:10.1016/j.jastp.2006.07.022, PAGES 234--248, 2007.
- Bristow, W. A., R. A. Greenwald, Shepherd, S. G., J. M. Hughes, On the observed variability of the cross-polar cap potential, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 109, NO. A2, A02203, doi:10.1029/2003JA010206, 2004.
- Shepherd, S. G., J. M. Rhuohoniemi, and R. A. Greenwald, Direct measurements of the ionospheric convection variability near the cusp/throat, GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 21, 2109, doi:10.1029/2003GL017668, 2003.
- Shepherd, S. G. and F. Shubitidze, Method of auxiliary sources for calculating the magnetic and electric fields induced in a layered Earth, JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS, VOL. 65, NO. 10, PAGES 1151--1160, doi:10.1016/S1364-6826(03)00159-7, 2003.
- Shepherd, S. G., J. M. Rhuohoniemi, and R. A. Greenwald, Testing the Hill model of transpolar potential with Super Dual Auroral Radar Network observations, GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 1, 1002, doi:10.1029/2002GL015426, 2003.
- Greenwald, R. A., Shepherd, S. G., T. S. Sotirelis, J. M. Ruohoniemi, and R. J. Barnes, Dawn and dusk sector comparisons of small-scale irregularities, convection, and particle precipitation in the high-latitude ionosphere,, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. A9, doi:10.1029/2001JA000158, 2002.
- Shepherd, S. G., R. A. Greenwald, and J. M. Rhuohoniemi, Cross polar cap potentials measured with Super Dual Auroral Radar Network during quasi-steady solar wind and interplanetary magnetic field conditions, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. A7, doi:10.1029/2001JA000152, 2002.
- Rhuohoniemi, J. M., S. G. Shepherd, and R. A. Greenwald, The response of the high-latitude ionosphere to IMF variations, JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS, VOL. 64, NO. 2, PAGES 159-171, JANUARY, 2002.
- Rhuohoniemi, J. M., R. J. Barnes, R. A. Greenwald, and S. G. Shepherd, The Response of the high-latitude ionosphere to the coronal mass ejection event of April 6, 2000: A practical demonstration of space weather nowcasting with the Super Dual Auroral Radar Network HF radars, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 106, NO. A12, PAGES 30085-30097, DECEMBER 1, 2001.
- Shepherd, S. G. and J. M. Rhuohoniemi, Electrostatic potential patterns in the high latitude ionosphere constrained by SuperDARN measurements, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 105, NO. A10, PAGES 23,005-23,014, OCTOBER 1, 2000.
- Shepherd, S. G., R. A. Greenwald, and J. M. Rhuohoniemi, A Possible Explanation for Rapid, Large-Scale Ionospheric Responses to Southward Turnings of the IMF, GEOPHYSICAL RESEARCH LETTERS, VOL. 26, NO. 20, PAGES 3197-3200, OCTOBER 15, 1999.
- Shepherd, S. G., J. LaBelle, G. Rostoker, and C. W. Carlson, The latitudinal dynamics of auroral roar emissions, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 104, NO. A8, PAGES 17,217-17,232, AUGUST 1, 1999.
- Shepherd, S. G., J. LaBelle, R. A. Doe, M. McCready, and A. T. Weatherwax, Ionospheric structure and the generation of auroral roar, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 103, NO. A12, PAGES 29253-29266, DECEMBER 1, 1998.
- Shepherd, S. G., J. LaBelle, and M. L. Trimpi, Further investigation of auroral roar fine structure, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 103, NO. A2, PAGES 2219-2229, FEBRUARY 1, 1998.
- Yoon, P. H., A. T. Weatherwax, T. J. Rosenberg, J. LaBelle, Shepherd, S. G., Propagation of medium frequency (1--4 MHz) auroral radio waves to the ground via the z-mode radio window, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 103, NO. A12, PAGES 29267-29275, DECEMBER 1, 1998.
- Shepherd, S. G., J. LaBelle, and M. L. Trimpi, The polarization of auroral radio emissions, GEOPHYSICAL RESEARCH LETTERS, VOL. 24, NO. 24, PAGES 3161-3164, DECEMBER 15, 1997.
- LaBelle, J., S. G. Shepherd, and M. L. Trimpi, Observations of auroral medium frequency bursts, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 102, NO. A10, PAGES 22221-22231, OCTOBER 1, 1997.
- Letcher Jr., D. M. Shook, and S. G. Shepherd Relational geometric synthesis: Part 1--framework, COMPUTER-AIDED DESIGN 27 (11): 821-832 NOV 1995.
- Office: 212 Cummings Hall
- Telephone: (603) 646-0096
- E-mail: simon at thayer.dartmouth.edu | <urn:uuid:1cbf4ae7-9766-4b56-ac91-93959785f7ba> | 3.203125 | 2,487 | Knowledge Article | Science & Tech. | 63.492245 |
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Berkeley Lab is a leader in investigating the complex coupled effects of thermal, hydrological and chemical processes driven by the heat generated from radioactive waste decay. In collaboration with other national laboratories, Berkeley Lab conducted in situ thermal tests at the Yucca Mountain Exploratory Studies Facility (ESF). Such field tests evaluate the effects of waste-generated heat on the flow system. They provide data to test models used in the repository design, achieving the optimal waste-heat load. This program again exemplifies the approach of iterative field testing and modeling for test design, test evaluation, and model refinement.
The overall objective of the underground heater tests in ESF Alcove 5 to acquire a more in-depth understanding of the coupled thermal, hydrological, mechanical, and chemical processes (THMC) at Yucca Mountain, by implementing a close integration of modeling and measurements. THMC measurements included passive monitoring data on temperature, mechanical displacement, microseismic events, and relative humidity gathered by sensors installed in instrumented boreholes; periodic active testing by geophysical methods (electrical resistivity tomography, crosshole radar tomography, borehole neutron logging) and air injection tests to monitor the redistribution of moisture; and water and gas sampling. Model predictions were performed prior to heating. As the tests progressed, data were being continuously compared to model predictions, to shed light on model conceptualization of processes, and to reevaluate the accuracy of the numerical model.
The Underground Thermal Test Program consisted of the Single Heater Test (SHT) and the Drift Scale Test (SDT). The Single Heater Test, with a heating period of 9 months, involved a 5 m long and 4 kW line heater during 1996 and 1997. The Drift Scale Test had 9 canister heaters in the Heated Drift, and 50 wing heaters. Heating was initiated at 187 kW in December 1997, and the test was conducted over a period of 8 years.
The following links provide information on specific tests conducted under the heater testing program: | <urn:uuid:5108f68a-90ff-42e8-924b-c6c8fb04b746> | 2.75 | 428 | Knowledge Article | Science & Tech. | 20.923619 |
The sites of the first detailed account of Cyanophyta in the Ross Sea Region (West and West, 1911) collected by Shackleton's 1907-09 expedition were revisited and detailed descriptions of Oscillatoriaceae (the most abundant family of Cyanophyta) occurring in abundance as thick felts covering the bottom of ponds, lakes and streams were recorded. Samples were collected for culturing studies from pond, stream and soil habitats at Cape Royds and in the Garwood Valley. Illustrations were made of representative specimens of all taxa encountered and measurements of the widths of large numbers of trichomes were made. Environmental data was collected and included pH, water conductivity and water temperature.
The algae culture collection is stored in a -20 freezer at the Molecular Laboratory and Allan Herbarium at Landcare Research, New Zealand. It is unknown what cultures are still viable and what species are available. The lab has PC2 containment and transfers have to be done according to Ministry of Agriculture and Fisheries (MAF) protocol. Contact Phil Novis: NovisP@landcareresearch.co.nz for more information.
The data is well described and documented in the publications. Some cultures may still exist and are held by Landcare Research, New Zealand. The quality of these cultures is unknown. Field notebooks, diaries, etc are retained by the investigator.
If the cultures are wanted to be transeferred from Landcare Research, the receiving lab needs to have the necessary containment certification (i.e. PC2 containment) and transfers have to be done according to MAF protocol. Otherwise the work needs to be done in the Landcare Research Molecular lab. | <urn:uuid:389325dc-27fa-436e-b3ee-e5fef61c1118> | 3.21875 | 341 | Knowledge Article | Science & Tech. | 33.386197 |
Tuesday, April 27, 2010
Guess What Else the Devils Hole Pupfish have had to put up with over the last 20,000 years?
I wrote about the precarious existence of the Devils Hole Pupfish a few months ago. The highly endangered fish live in a single cavern opening in the Death Valley region in water that is at a constant 92 degrees or so. They've had to put up with a lot over the years: declining lakes and rivers as the ice ages ended, predation, blazing hot temperatures, isolation and inbreeding, and human disturbances, garbage, groundwater pumping, and intrusive biologists measuring every aspect of their existence. Cameras monitor their every move. So what else?
The USGS camera monitors at Devils Hole caught the effects of the shaking of the Easter Sunday 7.2 magnitude El Mayor-Cucapah earthquake. Although Devils Hole is situated hundreds of miles away from the quake epicenter in Baja California, the water was disturbed by the waves passing through the region. And from looking at the video, 'disturbed' is a gentle term; the water was sloshing rather violently. The fish look a little confused, but were apparently not adversely affected, although sediment was redistributed about the small ledge where they derive most of their food. Not that any single fish would remember it, but the small pond has probably been shaken hundreds of times in the last 20,000 years that they have been isolated here, and they still survive.
Read the USGS analysis here. If the link to the video above doesn't work, try here. Thanks to Lee Allison of Arizona Geology, and Dave Schumaker at Geology News for the catch. | <urn:uuid:64edbc0e-8074-4cd2-bd85-713c837e4977> | 3.21875 | 343 | Personal Blog | Science & Tech. | 48.038055 |
an element a of a group is the smallest positive integer m such that a^m = e (where e denotes the identity element of the group, and a^m denotes the product of m copies of a). If no such m exists, we say that a has infinite order. All elements of finite groups have finite order.
can some1 give me an easy examples using the above facts please? thanks | <urn:uuid:744383e6-79f8-4fc0-bba0-1f8c55d41a72> | 3.5625 | 82 | Q&A Forum | Science & Tech. | 59.755357 |
I am trying to solve this problem, but getting nowhere, any help would be greatly appreciated!
What is the net gravitational force exerted on a 3.00 X 10^4 kg spaceship halfway between the Earth and the Moon. The average distance between the Earth and the Moon is 384,000 km. The Earth's mass is 5.98 X 10^24 kg, and the Moon's mass is 7.36 X 10^22 kg.
I am confused. | <urn:uuid:ae0a7c28-3054-4858-8c00-6b4e04b9b4dd> | 2.6875 | 95 | Q&A Forum | Science & Tech. | 105.831058 |
"How to address this student misconception? Atmosphere is necessary to create gravity"
My gut-response tweeting at the time was this:
"Engage with it: Ask them to elaborate on their idea... ask them draw pictures, to help explain how it works..."Now I've had time to digest it a bit more
followed by, "There is a meaningful correlation: b/c gravity is pulling, there is a lot more air near the earth. [It's] just not causal."
"Oh, and air collectively pushes UP, because it provides a buoyant force. So maybe helping student to see that?"
First, it has been and continues to be a struggle for scientists to understand phenomena that seem to involve actions occurring over a distance. While Newton's framework for gravity proposed a universal law of gravitation that acted instantaneously over a distance, physicists have worked hard not to do so. Physicists invented the concepts of electric and magnetic fields, partially because they function as intermediary objects that span distances. In the field view, the field at a point responds to neighboring points in such a way that disturbances propagate at the speed of light. In a somewhat alternative attempt, physicists invented intermediary particles like photons to function as energy and momentum carriers over those distances. With gravity, general relativity proposes that space itself is a intermediary that changes in response to mass, and those changes, too, propagate at the speed of light. In contemporary quantum physics, physicists and philosophers still don't fully grasp the causal implications of quantum entanglement, because they seem to imply "spooky" actions at a distance.
Second, it seems relevant to think of air molecules as carriers of momentum and energy, and thus could be considered force carriers. For example, air is the medium responsible for drag and buoyant forces. The interesting thing about the student idea that air causes gravity is that, in their idea, somehow the air causes a downward force. Perhaps they are focusing on how air pressure pushes down? Well it does push down, it just happens to also push up, and to the side, and every which way. In our mind, objects experience an upward buoyant force due to air as a result of all that pushing. What do students think? We can only know if we ask and engage.
This is a bit of why I tweeted, "Engage with it". If I don't know why my students think atmosphere is necessary for gravity, I don't know enough about their idea to know what to do next. If my students don't know why they think atmosphere is necessary, than it's probably worth while asking them to elaborate and make drawings. They have to come to know their mind.
In my mind, given that (1) gravity seems to exist where there is atmosphere, and (2) gravity seems to have no visible causal mechanism, it seems perfectly natural for a person to infer that air plays a causal role in the effect of gravity. In students doing so, it's possible we are just seeing their commitments to empirical regularity and to causal mechanism, both very important pieces of doing science. If students are struggling to see spooky action at a distance, then perhaps they are being equally as skeptical as scientists have been for hundreds of years. Certainly we may think that students are crazy for thinking atmosphere creates gravity, but isn't it weirder to propose massless particle called "gravitons" or curved spacetime
In fact, it was without the weird notions of fields, gravitons, or curving space-time, that Newton had little choice but to give in to empirical and mathematical coherence of the universal law of gravitation. His law fit the data. But, keep in mind, that Newton could only do so when more empirically precise data of moving planets was made available by better optical instruments and calculus was available to understand better how that data could be made sense of in terms of the rate of rates of change. While causal mechanism was abandoned at the time, it was reintroduced later when new concepts and mathematics allowed for it.
What's the point?
It's tempting to think that students' wrong ideas can be simply described as misconceptions concerning an isolated topic X. I am always skeptical of that position.
In this case of atmosphere causing gravity, students' ideas are entangled in a large web, including the notions of action at a distance, causal mechanism, empirical precision, astronomy, rates of change, buoyancy, air pressure, spacetime, particles as force carriers, etc. In that web, they are entangled with the historical and contemporary puzzles in physics that have not fully been resolved. Certainly they are just beginning to make contact with those puzzles, but I believe it is our job to help students make meaningful contact with puzzles that arise in the web. It is our job to help them become better navigators of that web.
All and all, I think I would be tempted in a class to pursue these ideas (which seem to be about gravity) through buoyancy. Overtime, by helping students come to see air as providing an upward force, student have a genuine puzzle to resolve on their own terms: if air pushes up, what's pulling down? If not that route, I would simply "engage with it", by saying, "That's a good idea. How would that work, air causing gravity?" | <urn:uuid:17e0a989-94d7-4d9d-8305-8793fca7ca50> | 3.328125 | 1,092 | Personal Blog | Science & Tech. | 47.277559 |
GLORIA – Global Observational Research in Alpine Environments
The Himalaya are experiencing the most drastic global climate change outside of the poles with predicted temperature increases of 5-6oC, 20-30% increase in rainfall, and rapid melting of permanent snows and glaciers. We have established a 1500km trans-Himalayan transect in Tibetan China, Bhutan and Nepal to document the affects of climate change on alpine plants and peoples (Figure 1). Initial data show that Himalayan alpine plants respond to environmental variables including elevation, precipitation, and biogeography and that people use these plants as medicines and for yak grazing. Since climate change is expected to majorly affect both precipitation and temperature (for which elevation is a proxy), we anticipate great changes in Himalayan alpine vegetation as we begin re-monitoring our long-term sampling sites in 2012 – seven years after the initial site was established.
GLORIA protocol (www.gloria.ac.at) prescribes four summits at each major site ("target area") chosen along an elevational gradient between treeline and permanent snowline to represent four ecotones: subalpine-lower alpine, lower alpine-upper alpine, upper alpine-subnival, and subnival-nival. Each summit is divided into 8 sections facing the cardinal directions (N, S, E, W) with 4 sections ranging from the summit down 5m in vertical elevation and another 4 sections ranging from 5m to 10m vertical elevation. Within summit sections, all species and their relative abundance are recorded. Additionally, at 5m vertical distance below the highest summit point in each of the 4 cardinal directions, a 3x3m grid is laid. In the 4 corner, 1x1m quadrats, all species are recorded as well as their frequency and percent cover. Soil temperature data are collected from buried wireless mini data loggers (Geo Precision M-Log5W) in the center of the 3x3m grids.
Our study sites (Figure 1) span across 1500km from the Hengduan Mountains of NW Yunnan, China in the east to western Nepal near Mt Annapurna. At each major site are 3-4 summits inventoried for plant species, frequencies, cover and relative abundance at elevations, latitudes and longitudes as listed on the study site page.
Alpine plants are identified both in the field and confirmed with vouchers deposited at the Missouri Botanical Garden and national/local herbaria including the Shangri-La Alpine Botanical Garden (SABG), NW Yunnan, China; Kunming Institute of Botany (KUN), Yunnan, China; the national herbarium at the National Biodiversity Centre (THIM), Thimphu, Bhutan; and Tribhuvan University Herbarium (TUCH), Kathmandu, Nepal. These vouchers can be referenced here. | <urn:uuid:a41cf482-b351-459a-ab17-a8c41bf2e87f> | 3 | 606 | Academic Writing | Science & Tech. | 23.338504 |
Climate Witness: Leonor Corral, Philippines
I have lived in El Nido most of my life and am a living testament to how the years have changed it. Before, we had a defined dry and wet season. Typhoons never reached our area. We always had fish and squid in abundance and boasted of a water system that reached all families – a year-round freshwater supply for rice fields and households.
The El Niño phenomenon that rocked the country in 1998 gave us our first experience of coral bleaching and its costly aftermath. We were very hard-hit because the fish yield has significantly decreased since then – and a lot of people have livelihoods that depend on the bounty of the sea. My brother used to fish in front of the town and as a family, we caught squid. Nowadays? You’re lucky if you can come up with five or ten kilos.
Today, typhoons are common – even in the Calamianes islands up north. We bear the brunt of the heavy flooding and the soil erosion that comes with it. The coconut trees that once dotted our coastlines are no more and floods now reach the town. Freshwater is scarce now – it does not reach everyone. We are still trying to find a good water source. On top of all this, more and people are migrating to El Nido, further straining the resources.
In pursuit of a living planet
El Nido is guided by the vision of sustainable development. To combat the effects of climate change, we are enforcing strict environmental protection. Each town is required to declare their own watershed areas and marine sanctuaries. The fisheries code is being strongly enforced. We have set up alternative livelihood programs to help people cope with decreasing fish yields – seaweed culture, mariculture, crab fattening, organic hog-raising and even mangrove reforestation projects as alternatives to producing charcoal. We even have personnel dedicated to guarding the environment.
Climate change is affecting us right now. All our programmes will be useless if we don’t protect the environment.
Scientific reviewReviewed by: Dr Rodel Lasco, Philippines Programme Coordinator, World Agroforestry Centre, ICRAF, Philippines
Leonor’s observations on coral bleaching during El Nino years is consistent with glbal observations as a result of higher sea temperatures.
However her observation on increased typhoons is not supported by peer-reviewed literature and observations by the weather bureau (PAGASA). PAGASA records show that the number of typhoons throughout the Philippines has remained more or less the same. Then again, in central Philippines, a slight increase in number of typhoons has been recorded and this could be the case in Palawan. Still at this point, her observation could be accounted for by climate variability.
In the future, most climate models show an increasing trend in rainfall and extreme events. So Leonor’s observations maybe a good indication of potential climate impacts in the area.
All articles are subject to scientific review by a member of the Climate Witness Science Advisory Panel. | <urn:uuid:8f10ac95-acc6-4ceb-9977-4172c68ba11a> | 2.953125 | 629 | Knowledge Article | Science & Tech. | 42.489159 |
The planet candidate around HD 100546 was detected as a faint blob located in the circumstellar disk revealed thanks to the NACO adaptive optics instrument on ESO’s VLT, combined with pioneering data analysis techniques. The observations were made using a special coronagraph in NACO, which operates at near-infrared wavelengths and suppresses the brilliant light coming from the star at the location of the protoplanet candidate.
According to current theory, giant planets grow by capturing some of the gas and dust that remains after the formation of a star. The astronomers have spotted several features in the new image of the disk around HD 100546 that support this protoplanet hypothesis. Structures in the dusty circumstellar disk, which could be caused by interactions between the planet and the disk, were revealed close to the detected protoplanet. Also, there are indications that the surroundings of the protoplanet are potentially heated up by the formation process.
Adam Amara, another member of the team, is enthusiastic about the finding. “Exoplanet research is one of the most exciting new frontiers in astronomy, and direct imaging of planets is still a new field, greatly benefiting from recent improvements in instruments and data analysis methods,” he said. “In this research, we used data analysis techniques developed for cosmological research, showing that cross-fertilization of ideas between fields can lead to extraordinary progress.”
Although the protoplanet is the most likely explanation for the observations, the results of this study require follow-up observations to confirm the existence of the planet and discard other plausible scenarios. Among other explanations, it is possible, although unlikely, that the detected signal could have come from a background source. It is also possible that the newly detected object might not be a protoplanet, but a fully formed planet that was ejected from its original orbit closer to the star. When the new object around HD 100546 is confirmed to be a forming planet embedded in its parent disk of gas and dust, it will become an unique laboratory in which to study the formation process of a new planetary system.Candidate protoplanet, circumstellar disk, data analysis, HD 100546 <BR/> | <urn:uuid:8d6a8e40-45a4-437e-9384-7a73fbe894e7> | 2.984375 | 451 | Content Listing | Science & Tech. | 23.743051 |
A list of numbers that follows a rule is called a sequence. Sequences whose rule is the addition of a constant are called arithmetic sequences, similar to geometric sequences that follow a rule of multiplication. Homework problems on arithmetic sequences often ask us to find the nth term of a sequence using a formula. Arithmetic sequences are important to understanding arithmetic series.
So an arithmetic sequence is a special kind of sequence where to get from one term to the next you either add or subtract a set difference every single time. So for this particular example we go from 13 to 10 to 7 to 4. What we're doing is subtracting 3 every time to get to the next term. And the cool thing about arithmetic sequences is that we can actually get general formulas for them, okay?
So what we have is what we call a common difference, which for an arithmetic sequence is typically abbreviated as d. And that is what we add to every term to get the previous term. So in this particular example, what we add to 13 to get 10 is -3. So your d in this case is negative, which is perfectly fine. If our d was positive our terms would be getting larger, okay? And what we're going to do is just sort of general case of figuring out the general term for an arithmetic sequence. Okay.
So what we have is, if we're given a1, a1 is just going to be our first term. Easy enough. To get our second term, all we do is we take our first term and add in that difference. So our first term here was 13, we added in a difference of -3 to end up with 10, okay?
To get the third term all we do is take the second term a sub 2 and add the d again. But the cool thing about this is we can actually have a statement for a sub 2 so what we end up with is, this is just going to be a sub 1 plus d plus d which works out to be a sub 1 plus 2d. Okay? Continuing on, a sub 4 is basically going to add another d to a sub 3. We're just adding a d every time in order to make it to next term. So we just add a d to this previous term and we end up with a sub 1 plus 3d. Okay. This is going to continue on and on to get a sub 5 we add in another d and so on and so fourth.
But what we can do then is just basically make a statement a sub n. a sub n is going to be the first term plus and if you notice for the second term we added one d, for the third term we added 2d's, for the fourth term we added 3d's. We're always adding one less d than the term number. So all we're doing for this is adding n minus 1 times d. Okay?
So through the [IB] this is for any arithmetic sequence for whenever you are adding or subtracting a set number to get the next term. You can always use the formula for your general term a sub n is equal to a sub 1 plus quantity an minus 1 times d in order to solve for information regarding each term. | <urn:uuid:a4518761-a860-47e6-b090-9166d3f3334f> | 4.28125 | 656 | Tutorial | Science & Tech. | 75.538554 |
Consider a point charge centered at the orgin surrounded by a ring charge in the xy plane. The point charge has a volve Q. The ring has charge density P and radius A.
A) Use coulomb's law to find the electric field at point, P(0,0,h) above the charge distribution.
B) Derive an equatio for the voltage as a function of height above the ring.
C) What is the value of Q as a functions of the density P required to canacelthe elctric field at the location (0,0,a) above the ring and point charge. | <urn:uuid:6e46241a-b66f-4c5d-b714-f658e9a72cfe> | 2.984375 | 132 | Q&A Forum | Science & Tech. | 73.869318 |
1.Climate change refers to a long-term shift in weather conditions. It is measured by changes in a variety of climate indicators (e.g. temperature, precipitation, wind) including both changes in average and extreme conditions. Climate change can be the result of natural processes and/or human activity.
2.Over most of Earth's history, natural processes have been responsible for periods of climate change. The Earth's climate has changed throughout its history long before human activity could have played a role. For example, the planet has swung between cold glacial periods or "ice ages", and warm interglacial periods over the last few million years. Changes in the past can be explained by natural factors such as changes in the Earth's orbit, in the sun's intensity, in the amount of explosive volcanic activity, by changes to the surface of the Earth, and farther back in time, to the position of the continents. Of these, only changes in the sun's intensity and volcanic activity are relevant on century timescales.
3.Human activity has now become the main cause of recent climate change. The strong global warming observed since the mid-20th century has been largely attributed to human influences on the climate. Global warming refers to the observed long-term rise in global average surface temperature and is one manifestation of climate change. The rate of global warming over the last half of the 20th century was about twice that for the whole century. This human influence results primarily from the burning of fossil fuels such as coal, oil, and natural gas. Burning these fuels generates carbon dioxide, a greenhouse gas. Land use changes, such as deforestation and conversion of land to agriculture, have also contributed carbon dioxide to the atmosphere.
4.Global warming is primarily attributed to the enhancement of the natural greenhouse gas effect. Greenhouse gases are so-named because they reduce heat loss from Earth to outer space. In this respect they act in a way that is similar to a greenhouse, creating warmer conditions than there would otherwise be, were these gases not present. Atmospheric concentrations of key greenhouse gases such as carbon dioxide, methane, nitrous oxide, and ozone have risen substantially as a result of human activity. This has enhanced or intensified the natural greenhouse effect.
5.The ozone hole is not the main cause of global warming. Global warming and ozone depletion (in the stratosphere) are issues with fundamentally different primary causes but they are interlinked in a number of ways. However, ozone depletion itself is not a principal cause of climate change. Changes in ozone and climate are directly linked because ozone absorbs solar radiation and is also a greenhouse gas. Stratospheric ozone depletion and increases in global tropospheric ozone that have occurred in recent decades have opposing contributions to climate change. The ozone-depletion contribution, while leading to surface cooling, is small compared with the contribution from all other greenhouse gas increases, which leads to surface warming. The total forcing from these other greenhouse gases is the principal cause of observed and projected climate change. Ozone depletion and climate change are indirectly linked because both ozone-depleting substances and their substitutes are greenhouse gases.
6.Climate change is a warming trend, not just a warming cycle. Global temperature naturally varies up and down from year to year and decade to decade. Natural climate variability will continue to have an influence on the state of the climate over short time periods, but superimposed on these natural fluctuations is a long term trend towards global warming. In order to detect climate change - a long term trend - above the 'noise' of natural climate variability, it is important to look to long term data records. When the record of global average surface temperature over the past 100 years or so is examined, a long term global warming of about 0.8 °C is observed.
7.Climate change will affect communities all over the world. Climate change is projected to lead to both changes in average conditions and in extreme weather events. Increases in droughts, heavy rains, floods, and severe storms, where these occur, can be very disruptive for society and are among the potential impacts of most concern. As well, rising sea levels will affect coastal areas, along which, in many regions, human communities are concentrated. Changes in temperature and precipitation will affect natural habitats and managed ones, with impacts on agriculture and food supplies of particular concern to a growing human population. There will be opportunities as well as risks associated with climate change, but in balance, impacts are expected to become increasingly negative as global average surface temperature becomes increasingly warmer.
8.Individuals, organizations and the international community can make a difference in dealing with climate change.We must act. Measures to reduce greenhouse gas emissions are essential to slowing the rate of climate change. Raising awareness of the issues surrounding climate change can make a significant difference.
9.The Government of Canada is half way to meeting its target of a 17%reduction in greenhouse gas emissions from 2005 levels, by 2020. See the Canada's Emissions Trends report for more information.
10.Canada has committed $1.2 billion in fast-start financing to help the world's developing nations reduce emissions and adapt to climate change. | <urn:uuid:9eaa0054-58ec-4137-a6a3-eead0a42f3c3> | 4.03125 | 1,048 | Knowledge Article | Science & Tech. | 32.902189 |
The ecological footprint is a measure of the area needed to support a population's lifestyle. This includes the consumption of food, fuel, wood, and fibres. Pollution, such as carbon dioxide emissions, is also counted as part of the footprint. Biocapacity measures how biologically productive land is. It is measured in 'global hectares': a hectare with the world average biocapacity. Biologically productive land includes cropland, pasture, forests and fisheries
EEA standard re-use policy: unless otherwise indicated, re-use of content on the EEA website for commercial or non-commercial purposes is permitted free of charge, provided that the source is acknowledged (http://www.eea.europa.eu/legal/copyright). Copyright holder: Global Footprint Network. | <urn:uuid:3a6bd830-3ead-44a9-be83-f1804aa70663> | 3.171875 | 163 | Knowledge Article | Science & Tech. | 28.290316 |
Spongilla lacustris Spicule
This is from a core sample collected in Lake Washington, Seattle, Washington.
Transmitted Brightfield Illumination
Spongilla lucustris is a freshwater sponge that is distributed widely around the world. It possesses megasclere,
microsclere, and gemmule spicules.
Significance in the Environment:
Pennak, Robert W., FRESH-WATER INVERTEBRATES OF THE UNITED STATES, 2nd Ed., Wiley Interscience, pp. 80-98, 1978.
(Identification Key for Freshwater Sponge Spicules)
Wilding, L.P. and L. R. Drees, "Distribution and implications of sponge spicules in surficial deposits in Ohio",
THE OHIO JOURNAL OF SCIENCE, vol. 68, no. 2, pp. 92-99, 1968.
(Transport Mechanisms for Spicules far from Lakes)
Kratz, T.K., K.E. Webster, C.J. Bowser, J.J. Magnuson, and B.J. Benson, "The influence of landscape position on lakes in northern
Wisconsin", FRESHWATER BIOLOGY, vol. 37, pp209-217, 1997.
(Environmental Factors Favoring Production of Sponge Spicules) | <urn:uuid:9e67cefc-1200-47b0-94b3-ecf9d9e17ebe> | 3.296875 | 286 | Knowledge Article | Science & Tech. | 55.134167 |
This example explores how to find the day of a month and the day of a week This example sets the year as 2007 and the day as 181. The example finds the day of a month and the day of a week by using get(field_name) method.
The Calendar class extends Object class. It is an abstract base class and converts a Date object into a set of integer fields. Calendar class provides a getInstance() method that returns a Calendar object whose time fields are initialized with the current date and time.
The methods used:
getTime(): This method is used to get current time from calendar.
getInstance(): This method gets a calendar using the default time zone , locale and current time.
The fields used:
WEEK_OF_MONTH: This field is used to get and set the week indicating the week number within the current month.
DAY_OF_WEEK: This field gets and set the day indicating the day of the week. This field takes values SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, and SATURDAY.
The code of the program is given below:
The output of the program is given below:
The date of Calendar is: Sat Jun 30 17:03:01 GMT+05:30 2007 The day of month: 30 The day of week: 7
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:7488c201-8fa3-4361-ba43-9c0ccbb3ce5f> | 3.796875 | 329 | Documentation | Software Dev. | 61.611743 |
This picture shows geysers near Triton's South Pole. The geysers shoot dark material high into Triton's atmosphere. This dark plume settles back down to Triton's surface. Scientists think we can tell which way the wind blows on Triton because of this! Do you see how the geyser plumes point from lower-left towards upper-right in this picture? Can you find any other geyser plumes (besides the two that the arrows point to) in this picture?
Image courtesy NASA/JPL/USGS. | <urn:uuid:44eda012-d043-4457-b159-1990563d797e> | 2.859375 | 120 | Truncated | Science & Tech. | 70.776429 |
A rise in global population as well as industrial and technological advancements in today’s world poses a serious threat to the future of our energy resources. With the impacts of climate change rapidly increasing every second, the international and even local communities are now initiating and going the extended mile on studying the feasibility of alternative energy sources.
Solar, wind, geothermal, biomass, and hydropower are the renewable energy resources being harnessed nowadays to support the huge demand for energy of the modern civilizations. But these are just a few of the many natural elements and are the only ones proven to be feasible at the time being.
Have you heard about the Dyson Sphere? For those who are new to this concept, the Dyson Sphere is a hypothetical mega structure that could extract huge amount of energy from a star by enveloping it with array of solar panels. A Dyson Sphere can provide a massive source of energy for the Earth’s consumption.
Sounds ambitious right? Watch this featured clip we have for you and be amazed yourself. The idea of the Dyson Sphere has been around for decades but has never been the priority in the field of science and discovery because of its implausible characteristic.
In this video, you will be further introduced to Dyson Sphere. This brief presentation is a very helpful source of the basic information you would like to know about this cosmic structure. Find more interesting knowledge on the Dyson Sphere project by starting to get to know more about it through this presentation.
From this and more, feel free to browse over our collection of informative articles and videos on renewable energy resources. Thanks for reading! | <urn:uuid:2dfb3121-0024-452c-be97-7bcd3d68b3ea> | 3.375 | 328 | Truncated | Science & Tech. | 35.099357 |
Short Summaries of Articles about Mathematics
in the Popular Press
"Gas on the Brain," by Clive Davidson. New Scientist, 3 October 1998, pages 37-39.
Neural computers are coming of age. They have medicaland financial applications, and they're likely to takecommand of the Space Shuttle when it docks with theInternational Space Station. These computers aremodeling what goes on in your head--neural networksare composed of interconnected, purely electronic neuronscalled nodes. However, due to feasibility constraints,these networks pale in comparison to the fast, productivehuman nervous system.
To increase the complexity of these networks, researchersin Skovde, Sweden are trying to exploit synaptic chemistry,developing what they call "gas nets." As in the brain,information in this network can be passed from node tonode not only by a direct connection, but also by a chemical--in this case nitric oxide. Many researchers consider this incorporation of brain chemistry a significant step in the field of artifical neural networks.
--- Ben Stein | <urn:uuid:fc17e6c7-b2a1-499d-92a8-ca52cc4336ce> | 2.84375 | 211 | Content Listing | Science & Tech. | 26.620314 |
A titrationThe gradual addition of one solution to another until the chemical amount of one reactant being added matches stoichiometrically the amount of another reactant in the solution initially present. is a volumetric technique in which a solutionA mixture of one or more substances dissolved in a solvent to give a homogeneous mixture. of one reactantA substance consumed by a chemical reaction. (the titrant) is added to a solution of a second reactant (the "analyte") until the equivalence pointThe point in a titration at which the amount of one reactant being added stoichiometrically matches the amount of another reactant initially present. The end point should match the equivalence point as closely as possible. is reached. The equivalence point is the point at which titrant has been added in exactly the right quantity to react stoichiometrically with the analyte. If either the titrant or analyte is colored, the equivalence point is evident from the disappearance of color as the reactants are consumed. Otherwise, an indicatorA substance for which a physical property (such as color) changes abruptly when the equivalence point is reached in a titration. may be added which has an "endpoint" (changes color) at the equivalence point, or the equivalence point may be determined from a titration curveA graph showing the progress of a titration; for example, a plot of pH or electrical conductivity versus volume of solution added.. The amount of added titrant is determined from its concentrationA measure of the ratio of the quantity of a substance to the quantity of solvent, solution, or ore. Also, the process of making something more concentrated. and volume:
- n(mol) = C(mol/L) x V(L)
and the amount of titrant can be used in the usual stoichiometric calculation to determine the amount of analyte.
The titration process can be observed in a Chemistry Comes Alive Titration Videos, or if these videos are not available from your workstation, on YouTube Videos. Using "titration" as the keyword in YouTube finds many videos, including of an acidIn Arrhenius theory, a substance that produces hydrogen ions (hydronium ions) in aqueous solution. In Bronsted-Lowry theory, a hydrogen-ion (proton) donor. In Lewis theory, a species that accepts a pair of electrons to form a covalent bond. titrated with baseIn Arrhenius theory, a substance that increases the concentration of hydroxide ions in an aqueous solution. In Bronsted-Lowry theory, a hydrogen-ion (proton) acceptor. In Lewis theory, a species that donates a pair of electrons to form a covalent bond. and phenolphtalein indicator.
A measured volume of the solution to be titrated, in this case, colorless aqueousDescribing a solution in which the solvent is water. acetic acid, CH3COOH(aq) is placed in a beaker. The colorless sodium hydroxide NaOH(aq), which is the titrant, is added carefully by means of a buret. The volume of titrant added can then be determined by reading the level of liquidA state of matter in which the atomic-scale particles remain close together but are able to change their positions so that the matter takes the shape of its container in the buret before and after titration. This reading can usually be estimated to the nearest hundredth of a milliliter, so precise additions of titrant can be made rapidly.
As the first few milliliters of titrant flow into the flask, some indicator briefly changes to pink, but returns to colorless rapidly. This is due to a large excess of acetic acid. The limiting reagentThe reactant (of two or more reactants) present in an amount such that it would be completely consumed if the reaction proceeded to completion. Also called limiting reactant. NaOH is entirely consumed.
The added indicator changes to pink when the titration is complete, indicating that all of the aqueous acetic acid has been consumed by NaOH(aq). The reaction which occurs is
CH3COOH(aq) + NaOH(aq) → Na+(aq) + CH3COO-(aq) + H2O(l) Eq (1)
Eventually, all the acetic acid is consumed. Addition of even a fraction of a drop of titrant produces a lasting pink color due to unreacted NaOH in the flask. The color change that occurs at the endpoint of the indicator signals that all the acetic acid has been consumed, so we have reached the equivalence point of the titration. If slightly more NaOH solution were added, there would be an excess and the color of the solution in the flask would get much darker. The endpoint appears suddenly, and care must be taken not to overshoot the endpoint.
After the titration has reached the endpoint, a final volume is read from the buret. Using the initial and final reading, the volume added can be determined quite precisely:
The object of a titration is always to add just the amount of titrant needed to consume exactly the amount of substanceA material that is either an element or that has a fixed ratio of elements in its chemical formula. being titrated. In the NaOH—CH3COOH reaction [Eq. (1)], the equivalence point occurs when an equal molar amount of NaOH has been added from the graduated cylinder for every moleThat chemical amount of a substance containing the same number of units as 12 g of carbon-12. of CH3COOH originally in the titration flask. That is, at the equivalence point the ratio of the amount of NaOH, added to the amount of CH3COOH consumed must equal the stoichiometric ratio
EXAMPLE 1 What volume of 0.05386 M KMnO4 would be needed to reach the endpoint when titrating 25.00 ml of 0.1272 M H2O2, given S(KMnO4/H2O2) = 2/5
Solution At the equivalence point, the stoichiometric ratio will apply, and we can use it to calculate the amount of KMnO4 which must be added:
The amount of H2O2 is obtained from the volume and concentration:
= 1.272mmol KMnO4
To obtain VKMnO4(aq) we use the concentration as a conversion factorA relationship between two units of measure that is derived from the proportionality of one quantity to another; for example, the mass of a substances is proportional to its volume and the conversion factor from volume to mass is density.:
= 23.62 cm3
Note that overtitrating [adding more than 23.62 cm3 of KMnO4(aq) would involve an excess (more than 1.272 mmol) of KMnO4.
Titration is often used to determine the concentration of a solution. In many cases it is not a simple matterAnything that occupies space and has mass; contrasted with energy. to obtain a pure substance, weigh it accurately, and dissolve it in a volumetric flask as was done in Example 1 of Solution Concentrations. NaOH, for example, combines rapidly with H2O and CO2 from the air, and so even a freshly prepared sample of solidA state of matter having a specific shape and volume and in which the particles do not readily change their relative positions. NaOH will not be pure. Its weightA measure of the gravitational force on an object; directly proportional to mass. would change continuously as CO2(g) and H2O(g) were absorbed. Hydrogen chloride (HCl) is a gasA state of matter in which a substance occupies the full volume of its container and changes shape to match the shape of the container. In a gas the distance between particles is much greater than the diameters of the particles themselves; hence the distances between particles can change as necessary so that the matter uniformly occupies its container. at ordinary temperatures and pressures, making it very difficult to handle or weigh. Aqueous solutions of both of these substances must be standardized; that is, their concentrations must be determined by titration.
EXAMPLE 2 A sample of pure potassium hydrogen phthalate (KHC8H4O4) weighing 0.3421 g is dissolved in distilled water. Titration of the sample requires 27.03 ml NaOH(aq). The titration reaction is
NaOH(aq) + KHC8H4O4(aq) → NaKC8H4O4(aq) + H2O
What is the concentration of NaOH(aq) ?
Solution To calculate concentration, we need to know the amount of NaOH and the volume of solution in which it is dissolved. The former quantity could be obtained via a stoichiometric ratio from the amount of KHC8H4O4, and that amount can be obtained from the massA measure of the force required to impart unit acceleration to an object; mass is proportional to chemical amount, which represents the quantity of matter in an object.
The concentration is
or 0.06197 M.
By far the most common use of titrations is in determining unknowns, that is, in determining the concentration or amount of substance in a sample about which we initially knew nothing. The next example involves an unknown that many persons encounter every day.
EXAMPLE 3 Vitamin C tablets contain ascorbic acid (C6H8O6) and a starch “filler” which holds them together. To determine how much vitamin C is present, a tablet can be dissolved in water andwith sodium hydroxide solution, NaOH(aq). The equation is
C6H8O6(aq) + NaOH(aq) → Na C6H7O6(aq) + H2O(l)
If titration of a dissolved vitamin C tablet requires 16.85 cm³ of 0.1038 M NaOH, how accurate is the claim on the label of the bottle that each tablet contains 300 mg of vitamin C?
Solution The known volume and concentration allow us to calculate the amount of NaOH(aq) which reacted with all the vitamin C. Using the stoichiometric ratio
we can obtain the amount of C6H8O6. The molar massThe mass of a mole of substance; the same as molecular weight for molecular substances. converts that amount to a mass which can be compared with the label. Schematically
= 308.0 mg
Note that the molar mass of C6H8O6
can be expressed in milligrams per millimole as well as in grams per mole.
The 308.0 mg obtained in this example is in reasonably close agreement with the manufacturer’s claim of 300 mg. The tablets are stamped out by machines, not weighed individually, and so some variation is expected. | <urn:uuid:be45f762-7bf3-4a93-a7f5-6a832ec41afb> | 3.890625 | 2,305 | Tutorial | Science & Tech. | 44.588892 |
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When you first use Visual Basic there is a great deal of pleasure to be had from the way you can draw a button on a form and start writing event handling code that makes the button do something.
Visual Basic has a lot of controls that you can use to build a user interface. As you progress you discover that none are quite as straightforward as the button. They are not difficult but a few words of explanation are necessary to make sure that you get full use out of them. So let's go beyond the button -
Step One - Variations on a button
A command button is easy to use because it is simple - you just click on it to make something happen.
There are two other types of button which behave differently - CheckBoxes and RadioButtons. Both buttons have a Checked property which can be True or False depending on whether or not the button is ticked (selected) or not. The CheckBox shows an X when it is selected and the RadioButton shows a circle.
You can use either type of button to allow the user to select options from a list. The big difference between the two types of button is that the RadioButtons on a form work as a group and only one of them can be selected at a time. CheckBoxes work independently of one-another and can be checked or unchecked as the user likes.
This means that you should use CheckBoxes for options that can be chosen independently of one another and option buttons for a set of mutually exclusive choices.
For example, if you are designing a form to allow a user to order breakfast (presumably over the Internet!) you might have three CheckBoxes for bacon, eggs and toast as these can be ordered in any combination but you might restrict their choice to one of tea or coffee by using two option buttons.
Each button also also has a range of events that it can respond to but in the main you don't need to write event handlers for CheckBoxes or RadioButtons because their values are processed when the user has finished filling in all of the details on the form. In most cases you have a standard button which is clicked to indicate that the user has finished entering data and making selections.
Step Two - Containers
Any RadioButtons that you place on a form work together - i.e. only one of them can be selected at a time.
You can interrogate the Checked property of each button to find out which one is pressed - nothing could be simpler.
Now imagine that we need to add some RadioButtons to give a user the choice of a daily newspaper as well as what to drink at breakfast. If all of the option buttons are on the same form the user will be a little surprised to find that clicking on the "Tea" button immediately cancels any request for a newspaper. The point is that ALL of the option buttons on a form work together.
The solution to this limitation is the GroupBox control - which unless you know about RadioButtons look as if it has no real function in life. The GroupBox acts as a sort of mini form within another form. Any controls that you draw on the GroupBox are located with reference to the GroupBox. For example, if you drag the GroupBox to a new location then its controls move with it. If you delete a frame then all of its controls are deleted as well.
The GroupBox is our first example of a control that is designed to hold or contain other controls - it is a container object. There are a number of other container objects that we will meet later.
You can see that the GroupBox is the ideal way of creating groups of controls. In the case of RadioButtons it is also the only way of creating more than one group of buttons that work together. Each set of RadioButtons in a particular GroupBox work as a group. So to create one set of buttons for tea or coffee and another set for newspaper we need one or two GroupBoxes.
If you have already created a set of RadioButtons, or any other control for that matter, and wish that you had put them inside a GroupBox then you can - but it isn't just a matter of dragging the controls over the GroupBox. If you do this you will end up with something that looks as if the controls are part of the GroupBox but they are not as you can soon prove when you try moving the GroupBox. To make the controls belong to the GroupBox you have to use Edit,Cut to remove the controls to the clipboard, select the GroupBox and then while it is selected use Edit,Paste to paste the controls into the GroupBox. Notice that this doesn't work if you paste while the GroupBox isn't selected. | <urn:uuid:989c4417-af21-4e5e-b12f-38d956b80652> | 3.640625 | 977 | Tutorial | Software Dev. | 55.711043 |
I know that a capacitor with a dielectric can operate normally up till a certain voltage (AFAIK called breakdown voltage) which depends on the strength of the dielectric placed between the plates. After this voltage, the circuit becomes short and current flows between the plates and thus the capacitor breaks down. But i want to know what is exactly happening when we say a dielectric "breaks down" ? What I know about a dielectric is that due to the electric field (because of the plates of the capacitor) the molecules of the dielectric align themselves accordingly and set up an electric field in the opposite direction, thus decreasing the net electric field. So, please can anyone tell me what happens during breakdown?
Breakdowns are electron cascades. There are different kinds:
1) Intrinsic breakdown of the material occurs when the electric field is sufficiently strong to ionize an atom of the dielectric (or accelerate a stray electron sufficiently to do the same), with the resultant new free electrons then being accelerated by the field to repeat the process with another atom. If more free electrons are produced than reattached, the process grows exponentially and breakdown results.
That said, intrinsic breakdown is rare, because other types of breakdown occur at much lower field strengths:
2) If there is a void in the dielectric material (a bubble) the residual gas in the void will break down at some (lower) electric field strength (again an electron cascade), and the freed electrons will strike the sides of the void, heating the dielectric and eroding it. This type of discharge is small and perhaps unnoticeable, but given enough time, the void will grow and eventually destroy the dielectric.
3) Surfaces between different materials (say the boundary between the dielectric and the material encasing the capacitor) can delaminate, again creating an empty space in which gas breakdown can occur. | <urn:uuid:078cb218-9a51-4f75-a2f2-5398a5ace244> | 3.5625 | 395 | Q&A Forum | Science & Tech. | 32.332394 |
|Paired male (above) and female (below)|
|Silkworm, 4th or 5th instar|
Bombyx mori mori
The Silkworm (Bombyx mori) is the larva or caterpillar of a moth that is important because it makes silk. It is entirely dependent on humans and no longer lives in the wild; silk has been made for at least 5000 years in China. Silkworms eat mulberry leaves. They are native to northern China.
Silkworms are very hungry. They eat mulberry leaves day and night. Silkworm eggs take about ten days to hatch. When the colour of their heads turns darker, it means that it is time for them to shed their skins. After they shed four times, their bodies turn slightly yellow and their skin becomes tighter, which means they are going to become a pupa. While they are a pupa, they turn into moths. Before becoming a pupa, the silkworm wraps itself in a cocoon, to help protect itself. The silkworm is called a silkworm because it spins its cocoon from raw silk that it makes in its mouth. Many other larva produce cocoons, but only a few silkworms are used to make silk.
The cocoon is made of one thread of raw silk from 300 to 900 meters (1000 to 3000 feet) long. The fibers are very thin. About 2,000 to 3,000 cocoons are needed to make a pound of silk.
If the animal is allowed to survive after spinning its cocoon, it will make a hole in the cocoon when it exits as a moth. This would cut the threads and ruin the silk. Instead, silkworm cocoons are thrown into boiling water, which kills the silkworms and also makes the cocoons easier to unravel. Often, the silkworm itself is eaten.
The adult silkworms (moths) cannot fly. The silkworm-moths have wings about 2 inches wide and a white hairy body. Females are about two to three times bigger than the males, but similarly colored. Adult silkworms have small mouths and do not eat.
Silkworm legends [change]
In China, there is a legend that the discovery of the silkworm's silk was by an ancient queen called Leizu. She was drinking tea under a tree when a cocoon fell into her tea. She picked it out and as it started to wrap around her finger, she slowly felt something warm. When the silk ran out, she saw a small cocoon. In an instant, she realized that this cocoon was the source of the silk. She taught this to the people and it became common. There are many more legends about the silkworm.
The Chinese guarded their knowledge of silk. It is said that a Chinese princess smuggled eggs to Japan, hidden in her hair. The Japanese also love silk. It takes 2100 silkworms to make a single kimono.
In Korea, silkworm pupae are boiled and seasoned, then eaten as a popular snack food known as beondegi.
In China, street vendors sell roasted silkworm pupae. The pupae are a delicacy in the Northern Area of China. They are baked with Satay sauces and rice to add extra flavour. In Japan, Silkworm Pupae is used in many dishes, including some types of sushi and even salads.
- Scoble, MJ, 1995. The Lepidoptera: Form, function and diversity. Princeton Univ. Press.
- Goldsmith, M, Toru Shimada, and Hiroaki Abe. 2004. The genetics and genomics of the silkworm, Bombyx mori. Annual Review of Entomology 50:71-100.
- Grimaldi and Engel, 2005. Evolution of the Insects. Cambridge University Press.
Other websites [change]
|Wikimedia Commons has media related to: Bombyx mori| | <urn:uuid:d81fd551-5efc-45a5-aacb-823d44a6d974> | 3.71875 | 815 | Knowledge Article | Science & Tech. | 65.611826 |
Function - Copy a region of virtual memory.
[in task send right]
The port for the task whose memory is to be copied.
The starting address for the source region. The address must
be on a page boundary.
The number of bytes in the source region. The number of
bytes must convert to an integral number of virtual pages.
The starting address for the destination region. The address
must be on a page boundary.
The vm_copy function copies a source region to a destination
region within the
same task's virtual memory. It is semantically equivalent to
by vm_write. The destination region can overlap the source region.
The destination region must already be allocated. The source region must be
readable, and the destination region must be writable.
This interface is machine word length specific because of the virtual address
The source region is protected against reading, or the destination
region is protected against writing.
An address is illegal or specifies a non-allocated region, or there is not
enough memory following one of the addresses. | <urn:uuid:d6f1db4e-03fb-496f-b1fb-0c6ca6f1667a> | 3.46875 | 222 | Documentation | Software Dev. | 46.767897 |
The development of the small guns began well before the beginning of the HARP Project. Some of the first experiments were conducted by Dr. Gerald Bull at the Canadian Armament and Research Development Establishment (CARDE) in the mid-fifties using guns as small as small as 76 mm. By the late fifties Dr. Bull's work had attracted the attention of the US Army's Ballistic Research Laboratory (BRL) and informal talks indicated there was considerable enthusiasm in the joint development of a gun-launched sounding probe. During late 1960 and early 1961 both CARDE and BRL conducted feasibility studies which indicated that reasonable payloads could be flown to considerable altitudes by gun-launched sub-calibre probes.
In early March 1960 these studies came to the attention of The US Army's Chief of Army Research and Development, Lt. Gen. Arthur Trudeau. At the time there was an almost desperate need for a low cost launch system which could cover the altitudes above those of aircraft or balloons to conduct extensive atmospheric research in support of the development of new supersonic aircraft and of missile systems. Lt. Gen. Trudeau realised that a low-cost gun-launched probe could quite likely solve this need. By July of 1960 BRL had proven the structural integrity of a small gun-launched probe in horizontal tests, but the project had to be scaled back as no funds were available for vertical test firings. By the end of 1960 the work at CARDE had been terminated primarily due to the difficulties encountered in setting up a joint, non-military program between BRL and CARDE. In early 1961 funds became available for BRL to conduct a few vertical test firings which proved the feasibility of this type of launch system. The lessons learned during these first tests led to a second generation of launch probes which were adopted by HARP a few years later.
The 5 inch L70 gun launchers used by HARP were provided by BRL and were based on a modified 120 mm T123 service gun. The major modifications to these guns were to smooth-bore the barrel, and to weld a second barrel section to the first. This lengthened the barrel to 8.9 m (29 feet). To maintain barrel alignment, three sets of stiffening wires were added, permitting an adjustable alignment relative to the firing angle. The standard gun carriage was mounted on a 45 degree platform to allow the barrel to be elevate to vertical for high altitude launches. The probes were rammed into the bore with a hydraulic jack to insure a consistent start pressure. A 16 kg (35 lb) charge of M17 propellant was loaded in a conventional brass shell case. The relatively small size and simplicity of these 5 inch gun launchers allowed them to retain their high mobility and they were easily transportable by truck, by train or by ship.
The portability of the of the 5 inch gun system allowed the HARP project to set up six launch sites across North America and in the Caribbean. These sites included Barbados; Highwater, Quebec; Ft Greely, Alaska; Wallops Island, Virginia; White Sands, New Mexico; and Yuma Proving Ground, Arizona. These sites provided a broad base of atmospheric conditions to study. The firings produced a wealth of atmospheric information which is still in use today.
The 5 inch HARP gun probes were a remarkable successful instruments and some 300 flights were conducted over a 5 year period during HARP. With the main propulsion stage (the gun launcher) being a reusable ground based system the launch costs were in the range of about $300-$500 each flight providing a remarkably low cost launch system, which was more then capable of fulfilling its HARP role. Details of the HARP 5 inch payloads are at HARP 5-1 and HARP 5-3.
by Richard K Graf
Payload: 10 kg (22 lb) to a 76 km altitude. Launch data is: complete. Launch Price $: 0.000 million in 1962 dollars.
AKA: High Altitude Research Project.
Status: Retired 1969.
Payload: 10 kg (22 lb).
Height: 1.16 m (3.80 ft).
Diameter: 0.13 m (0.42 ft).
Apogee: 76 km (47 mi).
Number: 300 . | <urn:uuid:5c41f6c0-6f62-4f04-ba35-79c526c391d7> | 3.453125 | 884 | Knowledge Article | Science & Tech. | 61.869774 |
Simply begin typing or use the editing tools above to add to this article.
Once you are finished and click submit, your modifications will be sent to our editors for review.
The dust is accompanied by gas, which is thinly dispersed among the stars, filling the space between them. This interstellar gas consists mostly of hydrogen in its neutral form. Radio telescopes can detect neutral hydrogen because it emits radiation at a wavelength of 21 cm. Such radio wavelength is long enough to penetrate interstellar dust and so can be detected from all parts of the Galaxy....
What made you want to look up "neutral atom"? Please share what surprised you most... | <urn:uuid:04e027d4-5af5-4cbb-9645-10ea41293b68> | 3.671875 | 127 | Knowledge Article | Science & Tech. | 57.593956 |
(click image to enlarge)
The climate is an incredibly complex and chaotic "system" that has billions, if not trillions, of annual/decade/century inputs that affect Earth's climate. In addition, scientists have little understanding of both the major and minor factors that impact climate; and, the climate modelers can only guess how all these factors and inputs interact. For example, one would think that the CO2 climate's sensitivity factor would be "settled" science but nothing is further from the truth. The IPCC employs some 20 climate models created by different groups of scientists and all these models differ in the climate sensitivity to CO2 factor utilized. Or, how about the "missing CO2"? Again, you'd think if the climate science is settled and the climate modelers were on top of their game they would make sure the climate models knew where all the human CO2 was going, right? Unfortunately, the climate models have no idea where at least 50% of human CO2 goes to, which if you think about it, makes predictions about climate change due to CO2 just about impossible to accomplish with any accuracy.
What other major problems (short-comings) do climate models have that cause the frequent and embarrassing climate prediction failures? What major 'climate influencers' (factors) are the models poorly representing? The chart below list 50 major 'climate influencer' problems, which represents only the tip of the climate model failure iceberg. So, is the IPCC the new Titanic about to be done in by the failure iceberg?
(Note: If C3 readers believe we missed other major problems with climate models, send your thoughts to "c3headlines" AT "mail.com". If we get enough submissions, we'll add a third 'problem' panel to chart.) | <urn:uuid:70cd3f48-c9f4-4ca6-b924-7b61d8715984> | 3.0625 | 364 | Listicle | Science & Tech. | 42.89875 |
In Fig. 20-60, determine the magnitude and direction of the
magnetic field at the midpoint of the side of the triangle between
wire M and wire N. The current in wires N and P is 8.80 A into the
page and the current in wire M is 8.20 A out of the page.
1 T at 2° (counterclockwise from the +x axis, which points to
the right in the figure) | <urn:uuid:b97bc793-0645-4143-90e7-9e95d96d32b8> | 2.984375 | 94 | Tutorial | Science & Tech. | 90.032438 |
Gray Wolf (Canis lupus)
Second only to humans in adapting to climate extremes, gray wolves once ranged from coast to coast and from Alaska to Mexico in North America. They were absent from the Southeast, which was occupied by red wolves (Canis rufus), and from the large deserts of the Southwest. By the early 20th century, government-sponsored predator control programs and declines in prey brought gray wolves to near extinction in the lower 48 States.
Wolves are social animals that live in groups, called packs, which typically include a breeding pair (the alpha pair), their offspring, and other non-breeding adults. Wolves are capable of mating by age two or three and sometimes form a lifelong bond. They can live 13 years and breed past 10 years of age. On the average, five pups are born in early spring and are cared for by the entire pack. For the first six weeks, pups are reared in dens. Dens are often used year after year, but wolves may also dig new ones or use some other type of shelter, such as a cave.
Pups depend on their mother’s milk for the first month, then are gradually weaned and fed regurgitated meat brought by pack members. By the time pups are seven to eight months old they are almost fully grown and begin traveling with the adults. After a year or two, young wolves may leave to try to find a mate and form a pack. Lone, dispersing wolves have traveled as far as 600 miles in search of a mate or territory.
Wolf packs live within territories, which they defend from other wolves. Their territories range in size from 50 square miles to more than 1,000 square miles, depending on the available prey and their seasonal movements. Wolves travel over large areas to hunt, as far as 30 miles in a day. Although they usually trot along at five miles per hour, wolves can run as fast as 40 miles per hour for short distances.
Studies at Yellowstone National Park are finding that the effect of wolves cascades throughout the park’s ecosystems. Ravens, foxes, wolverines, coyotes, bald eagles, and even bears benefit because they feed on carcasses of animals killed by wolves. Coyotes have declined because wolves view them as competition and keep them out of their territories; which may be responsible, in part, for an increase in small rodents. Elk changed their behavior to avoid wolf predation, which allowed willow, aspen, and cottonwood regrowth. This, in turn, provided food for beavers and habitat for songbirds. The ecosystem changes and cascading effects continue and are expected to do so for some time.
Wolves use their distinctive howl to communicate. Biologists have identified a few of the reasons wolves howl. First, they like to howl. They also howl to reinforce social bonds within the pack, to announce the beginning or end of a hunt, sound an alarm, locate members of the pack, or warn other wolves to stay out of their territory. Wolves howl more frequently in the evening and early morning, especially during winter breeding and pup-rearing.
Settlers moving westward depleted most populations of bison, deer, elk, and moose – animals that were important prey for wolves. Wolves then turned to sheep and cattle as a replacement for their natural prey. To protect livestock, ranchers and government agencies began an eradication campaign. Bounty programs initiated in the 19th century continued as late as 1965, offering $20 to $50 per wolf. Wolves were trapped, shot, dug from their dens, and hunted with dogs. Poisoned animal carcasses were left out for wolves, a practice that also killed eagles, ravens, foxes, bears, and other animals that fed on the tainted carrion.
By the time wolves were protected by the Endangered Species Act of 1973, only a few hundred remained in extreme northeastern Minnesota and a small number on Isle Royale, Michigan. Gray wolves were listed as endangered* in the contiguous 48 States and in Mexico, except in Minnesota where they were listed as threatened.** Alaska wolf populations number 7,700 to 11,200 and are not endangered or threatened.
The wolf’s comeback nationwide is due to its listing under the Endangered Species Act, which provided protection from unregulated killing and resulted in increased scientific research, along with reintroduction and management programs, and education efforts that increased public understanding of wolf biology and behavior. Today about 2,921 wolves live in Minnesota, 16 on Lake Superior’s Isle Royale, about 687 in Michigan’s Upper Peninsula, and at least 782 in Wisconsin.
In the northern Rocky Mountains, the U.S. Fish and Wildlife Service reintroduced gray wolves into Yellowstone National Park and U.S. Forest Service lands in central Idaho in 1995 and 1996. The reintroduction was successful by December 2010 there were at least 1,651 wolves in the northern Rocky Mountains of Montana, Idaho, and Wyoming.
The Mexican gray wolf, a subspecies, Canis lupus baileyi, has also been reintroduced into Arizona and New Mexico. Native to the Southwest, the wolves existed only in zoos until 1998, when 13 of the animals were released in Arizona. By the end of 2010, there were 50 wolves in the wild in Arizona and New Mexico with another 300 in zoos and other facilities. Since 2002, wolf packs have produced pups in the wild.
Gray wolf populations fluctuate with food availability, strife within packs, and disease. In some areas wolf populations may change due to accidental or intentional killing by people.
There is some concern that wolf recovery may pose a threat to human safety. However, wolf attacks on humans are extremely rare in North America, even in Canada and Alaska where there are consistently large wolf populations. Most documented attacks have been in areas where wolves became habituated to people when they were fed by people or attracted to garbage.
Special features of the Endangered Species Act have been used in parts of the wolf range to allow the removal of wolves that prey on livestock. There are programs to compensate for the loss of livestock and pets in most of the recovery areas.
The Mexican wolves in the southwestern United States are designated as non-essential, experimental populations under the Endangered Species Act. This designation allows more management flexibility while contributing to recovery.
Wolf recovery efforts have restored a top predator to its ecosystem, and improved our understanding of the complex interactions among species in their natural environments.
For more information:
*Endangered means a species is considered in danger of extinction throughout all or a significant portion of its range.
**Threatened means a species is likely to become endangered in the foreseeable future.
U.S. Fish & Wildlife Service
Fact Sheet Revised December 2011 | <urn:uuid:b413778d-f5ad-476b-b043-6b57986b5d15> | 4.125 | 1,398 | Knowledge Article | Science & Tech. | 43.875081 |
Amphorides (Amphorella) quradrilineata
Description: A common tintinnid ciliate in Mediterranean. It is about 150 microns long. Like other tintiinids, the ciliate cell which resembles an oligotrich ciliate is inside a shell or lorica. Tintinnids feed on phytoplankton, microscopic algae and in turn serve as food for larger plankton organisms such as copepods and fish larvae.
Author: Dolan, John
JPG file - 1.09 MB - 1700 x 1700 pixels
added on 2006-02-17 - 1016 views
WoRMS Taxa on this image:
Amphorides quadrilineata (Claparède & Lachmann, 1858) - checked by Dolan, John on 2013-03-15 08:17:43 | <urn:uuid:8455b540-3b06-44cb-84e1-588deda7db00> | 2.703125 | 184 | Truncated | Science & Tech. | 50.408947 |
NOISE nuisance from aircraft can be reduced significantly by changing the way the planes come in to land. Lining up with the runway as far as 70 kilometres away and making a steady descent can more than halve the acoustic energy that reaches the ground, an international research consortium has found. Now pressure is on for the technique to be considered for London's Heathrow, the busiest international airport in the world.
Noise pollution around airports is set to get worse. Air traffic worldwide is increasing at 4.7 per cent per year and is expected to triple by 2030. Without a major initiative to reduce aircraft noise, airports will be prevented from handling the extra flights, says Mike Howse, director of technology and engineering at the British aero-engine maker Rolls-Royce.
The noise during descent comes from two sources: the engines, particularly when they have to deliver high power as the plane ...
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content. | <urn:uuid:86fd4efc-aa36-430a-8b22-52167be15838> | 3.578125 | 208 | Truncated | Science & Tech. | 47.714052 |
Fabius-Pompey Central School
Fabius-Pompey Central School students and high school chemistry teacher, Tim Bloom, examine the contents of their net to see what kind of macroinvertebrates they caught in Fabius Brook.
Ten students and two teachers participated in the stream survey.
Other students look at their results for dissolved oxygen, a test that determines how much oxygen is found in a 25 ml sample of water.
Mat Webber has the students' undivided attention as he talks about the stream's chemical results. He explains the results from chloride, phosphate, nitrate, turbidity and total dissolved solids tests that were taken to help determine the health of the stream. | <urn:uuid:53aee2d9-706b-4e38-994c-5b5b033749a7> | 2.765625 | 146 | Truncated | Science & Tech. | 46.553872 |
Aug. 5, 2009 The Naval Research Laboratory's satellite suite, the Atmospheric Neutral Density Experiment 2 (ANDE-2), was deployed from NASA's Space Shuttle Endeavour on July 30, 2009.
The ANDE-2 satellite suite consists of two nearly perfectly spherical micro-satellites with instrumentation to perform two interrelated mission objectives. The first objective is to monitor the total atmospheric density along the orbit for improved orbit determination of resident space objects. The second is to provide a test object for both radar and optical U.S. Space Surveillance Network sensors.
ANDE-2 is a low-cost mission designed to study the atmosphere of the Earth from low-Earth orbit by monitoring total atmospheric density between 300 and 400 km altitude. ANDE-2 data will be used to improve methods for the precision orbit determination of space objects and to calibrate the Space Fence, a radar space surveillance system belonging to the Air Force 20th Space Control Squadron, a principal resource for tracking low-Earth orbiting space satellites.
Other social bookmarking and sharing tools:
Note: If no author is given, the source is cited instead. | <urn:uuid:c05c62b7-b1b5-4d60-a306-e4be18db6210> | 3.3125 | 232 | Knowledge Article | Science & Tech. | 33.948311 |
Image: Image generated by Tom Bartol Salk Institute for Biological Studies in collaboration with Justin Kinney, Dan Keller, Chandra Bajaj, Mary Kennedy, Joel Stiles, Kristen Harris and Terry Sejnowski
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If you could pause time for an instant and make yourself small enough to discern individual molecules, the far right of this image is what you might see when one brain cell communicates with another across a synapse—the point of contact between two nerve cells. How the brain senses, thinks, learns and emotes depends on how all its nerve cells, or neurons, communicate with one another. And as a result, many laboratories are working feverishly to understand how synapses function—and how psychiatric drugs, which target them, improve patients’ lives.
Yet neuroscientists are hobbled by the fact that synapses are extremely complex, vanishingly small and extraordinarily fast. Thanks to the coordinated efforts of over 1,400 types of molecules, one neuron communicates with another by spitting out chemical neurotransmitters that carry its message across a thin gap to a receptive surface on its partner. The only way to provide a full account of what goes on at the synapse is to build a computer model that is as realistic as possible. The hope is that running a moment-by-moment, molecule-by-molecule simulation will yield novel insights that could then be tested experimentally.
This article was originally published with the title Signals in a Storm. | <urn:uuid:4f34963d-1e46-4833-bd70-37ca15dbcccf> | 3.328125 | 304 | Truncated | Science & Tech. | 22.695 |
The ongoing disruption of the earth’s climate by man-made greenhouse gases is already well beyond dangerous and is careening toward completely unmanageable. Under midrange projections for economic growth and technological change, the planet’s average surface temperature in 2050 will be about two degrees Celsius (3.6 degrees Fahrenheit) higher than its preindustrial value. The last time the earth was that warm was 130,000 years ago, and sea level was four to six meters higher than today. No one knows how long it will take sea level to “catch up” with such an increase; it could be several centuries, or it could be less.
Even with uncertainties, there is reason to believe that tipping points into unmanageable changes will become much more probable for increases larger than two degrees C. To achieve a better-than-even chance of not exceeding that figure, human emissions must start to decline soon, falling to about half of today’s level by 2050 and further thereafter.
Carbon dioxide (CO2) is the most important of civilization’s emissions and the most difficult to reduce. About 80 percent comes from burning coal, oil and natural gas; most of the rest comes from deforestation in the tropics. The largest emitters in 2006 were (in descending order) the U.S., China, Indonesia, Brazil, Russia, India, Japan and Germany. (Numbers are not final, but China appears to have passed the U.S. in 2007.)
There is no way to keep the temperature increase under two degrees C unless these big emitters start taking serious action almost immediately. The U.S. and the other industrial nations on the list have an obligation to lead this transition. They have caused most of the buildup of gases to date, and they have the largest per capita emissions, the greatest wealth and the most technology. And they agreed to their responsibility to lead in the United Nations Framework Convention on Climate Change of 1992, to which the U.S. and 191 other countries are parties.
Unfortunately, the Bush administration has wasted the last eight years. It should have been taking decisive action but engaged instead in systematic understatement of the danger: it has made ridiculous assertions that the U.S. should not do anything that China does not agree to do and has stubbornly insisted that no action should be taken to improve climate change “if it hurts the economy.” This last rationalization translates into “if it costs anybody any money” and is roughly akin to saying that the country should not defend itself against terrorism because that costs money.
There is now reason to hope, however, that this country is about to shift from shameful foot-dragging into the leadership role that the world needs and expects. Such a transition has been made possible by the convergence of several factors: a stream of new science showing an accelerating pace of climate change and its impacts; the everyday experience of people witnessing the change around them (and seeing it on the evening news); the compelling portrayals of what is happening and why, such as Al Gore’s documentary An Inconvenient Truth and the 2007 reports of the Intergovernmental Panel on Climate Change; and the shifting stances of constituencies as diverse as evangelical Christians (who argue for protecting the climate on grounds of stewardship of God’s creation) and military leaders (who argue on grounds of national security).
The impending political tipping point is evident in nationwide opinion polls and in the climate policies already embraced by more than 850 towns and cities and 32 states. It is also manifest in the rapid transition of attitudes among corporations, which have come to see climate-change mitigation and adaptation not only as necessities but as opportunities. When top executives from General Electric, DuPont, Duke Energy and Exelon testified before the Senate Committee on Energy and Natural Resources in favor of federal regulation of greenhouse gas emissions, this surely was the equivalent of the plastic thermometer in the turkey popping up to indicate that it’s done. | <urn:uuid:cf43b4f3-1ff4-497f-9b21-fab837b5624c> | 3.03125 | 810 | Nonfiction Writing | Science & Tech. | 39.748904 |
At the recent AAAS meeting, Stony Brook University’s Robert Crease talked about a doomsday scare involving Scientific American and Brookhaven National Lab’s Relativistic Heavy Ion Collider, or RHIC:
“As the accelerator neared completion in 1999, Scientific American ran an article about RHIC, called ‘A Little Big Bang,’ with the title referring to the machine’s ambition to study forms of matter in the early universe.”
A reader wrote in wondering if black holes might be created. Sci Am printed the letter with a considered response from physicist Frank Wilczek.
“Wilzcek said that the black hole scenario was incredible. But he also said that there’s a more likely possibility that it might create strangelets, which would swallow ordinary matter and described that as [merely] not plausible. That then prompted a series of headlines including this from the Sunday Times of London, entitled ‘Big Bang Machine Could Destroy Earth’.”
Scientific American, Brookhaven and the Earth survived. Wilczek won the Nobel Prize in 2004 for his earlier work.
[The above text is an exact transcript of this podcast.] | <urn:uuid:ad40dd44-5662-4c2e-a5aa-51e94fa8821b> | 2.984375 | 250 | Truncated | Science & Tech. | 38.948196 |
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Billion-Year-Old Water Preserved in Canadian Mine
Pockets of water trapped in rocks from a Canadian mine are over a billion years old, and the water could contain life forms that can survive independently from the sun, scientists said this week.
The ancient water was collected from boreholes at Timmins Mine beneath Ontario, Canada, at a depth of about 1.5 miles (2.4 kilometers).
“When these rocks formed, this part of Canada was the ocean floor,” said study co-author Barbara Sherwood Lollar, an Earth scientist at Canada’s University of Toronto.
“When we go down [into the mine] with students, we like to say imagine you’re walking on the seafloor 2.6 billion years ago.”
Working with U.K. colleagues Chris Ballentine and Greg Holland, Sherwood Lollar and her team found that the water was rich in dissolved gases such as hydrogen and methane, which could provide energy for microbes like those found around hydrothermal vents in the deep ocean. Read more. | <urn:uuid:942faffc-dff5-4f2b-a46a-7124b7de0705> | 3.359375 | 247 | Content Listing | Science & Tech. | 55.643411 |
Dieldrin is nonpolar and, therefore, has a strong affinity for organic matter and sorbs tightly to soil particulates based on its log Koc of 6.67. Volatilization is the principal loss process of dieldrin from soil. The process is relatively slow due to its low vapour pressure and strong sorption to soil. It may also be impeded by low soil moisture or incorporation of the compound into the soil. The volatilization rate decreases with time and increases with increasing temperature to a maximum at 25 °C.
Based on the Henry's law constant and the Koc, the volatilization halflife of dieldrin from soil has been estimated to be 2.5 years. Movement of dieldrin through the soil solution is extremely slow, indicating little potential for groundwater contamination. Analysis of environmental groundwater samples has shown that on some occasions, dieldrin has contaminated groundwater systems.
Based upon a Henry's law constant, volatilization of dieldrin from water surfaces is expected, however, may be attenuated by adsorption to suspended solids and sediment in the water column.
According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere, dieldrin, will exist in both the vapour and particulate phases in the ambient atmosphere. Dieldrin may be transported great distances in the atmosphere and be removed by wet or dry deposition.
Dieldrin has a high potential for bioaccumulation as indicated by a log Kow value that ranges from 4.32 to 6.2. This factor indicates, that dieldrin will bioconcentrate and biomagnifie in living organisms. | <urn:uuid:f63b5d74-1b20-42c0-aba6-ea81aaaa744c> | 3.109375 | 350 | Knowledge Article | Science & Tech. | 37.242455 |
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STEREO spacecraft Set for Launch.
Get set to see the Sun... in thrilling 3-D! At the end of August, NASA will launch its twin STEREO spacecraft into orbit around the Sun, to provide the first stereoscopic views of coronal mass ejections. The spacecraft will be lofted into space on Thursday, August 31, to begin a 2-year mission; one spacecraft will fly ahead of the Earth in its orbit, and the other will tail back. With this 3-D view, scientists will be able to accurately track the direction and speed of coronal mass ejections, providing much better space weather forecast.
At the end of this month, NASA is scheduled to put two eyeballs in orbit around the Sun to provide the first stereoscopic views of the immense magnetic explosions on the sun's surface that fling particles at Earth and create storms in space.
The twin spacecraft, called the Solar TErrestrial RElations Observatory (STEREO), will explore these massive explosions, or coronal mass ejections, which erupt as billowing magnetic storms that can dwarf the sun. Often more than 6 million miles across - the Sun is 860,000 miles in diameter - they can throw out a cloud of gas equivalent to the mass of Mount Everest at speeds of 5 million miles per hour.
This gas reaches Earth and clashes with the planet's own magnetic field, disrupting radio communications and threatening satellites and Astronauts while producing beautiful, Kodachrome auroras - the Northern and Southern lights.
The spacecraft is scheduled to launch from Kennedy Space Center, Fla., on Thursday, Aug. 31, for a two-year mission. One STEREO craft will precede and one will follow Earth in its orbit around the Sun to find out what the solar shock wave looks like elsewhere when Earth experiences an onslaught of charged particles.
“With STEREO, we have an unprecedented opportunity to make simultaneous measurements at several points along Earth's orbit, to find out what coronal mass ejections look like at different locations and different times. We have never had that before,” said Janet Luhmann, a research physicist at the University of California, Berkeley's Space Sciences Laboratory and a co-principal investigator on the mission.
Luhmann led a team that built a suite of instruments for STEREO that measures the energy of electrons and ions from the Sun and the intensity of the sun's magnetic fields. Called the In-situ Measurements of Particles And CME Transients (IMPACT), it is one of four instrument packages aboard the nearly identical spacecraft. Together, they provide data that will help pin down how and where the electrons and ions are accelerated in the sun's corona and atmosphere and how coronal mass ejections propagate through and interact with the steady solar wind.
“By taking a multipoint perspective, imaging as well as in situ measurements with IMPACT of coronal mass ejections, STEREO is supposed to give a definitive answer to the questions: What are these coronal mass ejections? How are they shaped? How do they evolve? Where do they come from?” Luhmann said.
As an experiment, UC Berkeley scientists also will turn the data sent back by IMPACT into stereophonic sound.
“It will provide a sound track to any movies that come out of STEREO images,” said Luhmann. “The sound is not just a gee whiz thing, but it conveys a sense of the physical processes in space, which are invisible.”
The “sonification” project is both a test to see whether researchers' ears can detect patterns in the measurements not obvious from visual or other analyses, and a way to engage the public in experiments that don't produce pretty pictures. Space Sciences Laboratory scientists have produced an educational and public Web site about the sonification project and IMPACT measurements.
IMPACT incorporates seven instruments that will measure the energies of the solar wind “plasma” electrons, ranging from the slower ones produced by flares to the high-speed electrons produced by coronal mass ejections; the most energetic of the ions - protons, helium and iron nuclei; and the local magnetic field. electron and magnetic field detectors are mounted on a 15-foot boom that points away from the sun.
“We might find, for example, that the Earth would experience a huge storm if it had been at the position of the head STEREO spacecraft, but there is nothing there at the position of the Earth,” Luhmann said. “We don't really have a good feeling for how broad these disturbances are. I think that with current modeling capabilities for space weather, combined with these multipoint measurements, we will finally sort this out and at the end be better able to forecast space weather.”
“In terms of space-weather forecasting, we're where weather forecasters were in the 1950s,” said Michael Kaiser, STEREO project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. “They didn't see hurricanes until the rain clouds were right above them. In our case, we can see storms leaving the sun, but we have to make guesses and use models to figure out if and when they will impact Earth.”
The twin STEREO spacecraft will be launched aboard a Delta II rocket and immediately slip into slightly different orbits near Earth. Then, two months after launch, a close flyby of the Moon will sling one of them into a 388-day orbit that causes it to lag behind the Earth by 22.5 degrees. A month later, the second spacecraft will fly near the Moon and be sling-shotted into a 346-day orbit at a position 22.5 degrees ahead of the Earth. Each year, these differing orbital periods will cause the spacecraft to drift farther apart - by 45 degrees each year - and farther from the Earth, until they eventually reach a point behind the Sun from Earth's perspective.
Each STEREO observatory, which is about the size of a golf cart, carries 16 instruments in all, including imaging Telescopes for optical photos, equipment to measure solar wind and more energetic particles, magnetometers and radio antennas, which also were built at the Space Sciences Laboratory under the direction of Stuart Bale, assistant professor of physics.
The United States, the United Kingdom and several European countries provided the various STEREO instruments. The instruments were integrated with the observatories by the Johns Hopkins University Applied physics Laboratory in Laurel, Md. NASA's Goddard Space Flight Center in Greenbelt, Md., is responsible for the project management. The NASA Launch Services Program at Kennedy Space Center and Boeing are responsible for the launch. The total U.S. cost of the mission is $478 million, with an additional $60 million coming from European contributions.
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Since NASA announced the Greenland ice sheet recently experienced “unprecedented” (in 30+ years of satellite measurements) ice sheet surface melt, countless news reports, commentaries and critiques have attempted to explain what it means.
Many have suggested the melting observed over 97 percent of Greenland’s ice sheet surface is of great signficance, while others aren’t as convinced. Considering the range of perspectives on this event, let’s try to synthesize them and perhaps get a weigh-in on the gravity of this meltdown.
It’s been unusually warm in Greenland
Large ridges of high pressure, or heat domes, have passed over Greenland one after another since June.
“Each successive ridge has been stronger than the previous one,” Thomas Mote, a climatologist at the University of Georgia, told NASA.
Meteorologist Jeff Masters at wunderground published the most thorough account of recent temperatures in Greenland. Masters wrote:
Temperatures at at the top of the Greenland Ice Sheet, 10,552 feet (3207 meters) above sea level, and 415 miles (670 km) north of the Arctic Circle, had risen above the freezing mark four times in the 12-year span 2000 - 2011. But in mid-July 2012, temperatures eclipsed the freezing mark on five days, including four days in a row from July 11 - 14.
More heat is coming Masters says:
[A]bove-freezing temperatures [are forecast] to return again by Saturday through Tuesday, with a high of 41°F (5°C) on Sunday. This would break the record warm temperature at Summit of 3.6°C set just two weeks ago.
The ice sheet is presently much darker than any point in the last 12 years
Jason Box, a polar climate researcher at Ohio State University, has developed a dataset of albedo - a measure of how reflective or “white” the Greenland Ice Sheet is. The albedo has plunged almost off the chart as the ice sheet is now less reflective, or “darker” than any time in 12 years of measurements due to melting. On Box’s blog the MeltFactor, he describes this statistical anomaly:
Averaged over the whole of the ice sheet, for nearly 2 months now, the ice sheet albedo has been ~2 standard deviations below the 2000-2012 average.
A similar melting event occurred in 1889 tied to similar atmospheric flow patterns
As warm as it’s been in Greenland and as much melting that has occurred, NASA says such an event happened about 125 years ago, in 1889.
Interestingly, the U.S. experienced very warm temperatures for at least a part of 1889 as well - just as it has this year (warmest on record in Lower 48 year-to-date based on data from 1895-2012).
This past March was the second warmest winter month ever recorded in the Midwest, with temperatures 15 degrees above average. The only other winter month that was warmer was December of 1889, during which temperatures were 18 degrees above average. Now, MU researchers may have discovered why the weather patterns during these two winter months, separated by 123 years, were so similar.
In both years the researchers found La Nina patterns built up large heat ridges over the central U.S. And just as a large heat dome established itself over Greenland this summer, it’s reasonable to project it did so in 1889 given the circumstances.
There exist a range of 1) beliefs about the melting’s link to manmade climate change and 2) future melting projections
Some researchers have been more cautious than others in linking this event to manmade global warming and projecting the future. But most agree the more these record temperatures and melting events occur, the more likely there is a connection.
Consider this viewpoint of a NASA scientists conveyed in Juliet Eilperin’s article in today’s Washington Post:
If satellites document the same degree of melting in August and next summer, said Dorothy Hall, a senior scientist at NASA’s Goddard Space Flight Center, “then we’re going to start to think it is related to global warming, but at this point we can’t say.”
On the other hand, William Colgan, a research associate at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado, told Climate Central’s Andrew Freedman we can connect the dots now:
“I think it is clear that entire ice sheet melt events are now increasing in frequency as a result of anthropogenic [manmade] climate change, rather than natural variability in solar insolation,” Colgan said.
But Colgan was more reluctant to project the future. From Freedman’s piece:
“In terms of the importance and significance of an entire ice sheet melt event: Obviously it gets you thinking the future of the Greenland Ice Sheet,” Colgan said in an email conversation. “But since we are looking at a record event, rather than a trend, it is not really possible to directly translate this into a projection of future ice sheet behavior.”
Taking the opposite position, Ohio State’s Jason Box believes these ice sheet changes validate his own aggressive projections about the future. He blogged:
In my recently accepted albedo paper (Box et al. 2012, ACCEPTED VERSION) ... the statement: “it is reasonable to expect 100% melt area over the ice sheet within another similar decade of warming.” may be coming true already.
Claims: NASA and some media have been fast and loose in their reporting
Leading voices among those unconvinced manmade climate change is a major problem have criticized some of the reporting about this event.
Though widely cited, NASA’s press release contains a contradiction says Pat Michaels, a senior scholar at the libertarian Cato Institute. On the one hand, NASA headlines the melting as “unprecedented” but deeper down discusses the similar melting event of 1889.
Michaels jumped on this contradiction in his World Climate Report blog.
“...apparently, when it comes to hyping anthropogenic global warming (or at least the inference thereto), redefining English words [unprecedented] in order to garner more attention is a perfectly acceptable practice,” Michaels said.
In NASA’s defense, it wrote [bold text indicates added emphasis]: “Satellites See Unprecedented Greenland Ice Sheet Surface Melt” which is literally true in the 30+ years of satellite observations. But someone not reading carefully could be misled...
In another alleged example of overstatement, Colorado State University’s Roger Pielke Sr., a professor of atmospheric science, offered a sharp critique of the Associated Press headline: “NASA: Sudden Massive Melt in Greenland”.
Pielke Sr. wrote on his blog:
The news headline, in particular, is an example of media hype. There was no “massive melt“. The term “massive” implies that the melt involved large masses of the Greenland icecap. They could have written “Sudden Extensive, Short-Term Surface Melting On the Greenland Icecap” but instead chose to overstate what is a short-term weather event.
Another not unfair critique, but borderline nit-picking, in my view...
Bottom line: A major surface ice sheet melting event occurred in Greenland coupled with highly unusual temperatures. A similar event occurred in 1889 and, thus, links to manmade climate change are not yet conclusive. On the other hand, a pattern of pronounced warming in the Arctic in recent decades and other indicators such as melting sea ice, glacier melt, etc. suggest manmade climate change increased the likelihood of an event of this magnitude. | <urn:uuid:7fb4b7f6-a898-4262-97f7-c865c3700fc0> | 3.796875 | 1,627 | Nonfiction Writing | Science & Tech. | 42.592824 |
COPYRIGHT T. M. BAUGH, USED BY PERMISSION
Figure 1. The tiny Devils Hole pupfish is less than an inch (2.5 cm) long but has played a big role in native species conservation.
The diminutive Devils Hole pupfish (Cyprinodon diabolis, fig. 1) in Death Valley National Park (California and Nevada) has played an outsized role in the history of native species conservation, including helping to motivate one of the earliest uses of federal reserved water rights to protect habitat of a species of no recreational or commercial value. However, water levels in Devils Hole are dropping and species numbers are declining (fig. 2). After more than three decades of research and monitoring, managers and researchers still do not have a complete understanding of the ecosystem of Devils Hole.
Return to top
This page updated:
18 October 2006
Suggested citation for this article:
Wullschleger, J. G., and W. P. Van Liew. 2005. Devils Holes revisited: Whay are pupfish numbers and water level dropping again? Park Science 23(2):1,3,26–30.
Available at http://www.nature.nps.gov/ParkScience/archive/PDF/Article_PDFs/ParkScience23(2)Fall2005_1_3_26-30_WullschlegerVanLiew_2495.pdf.
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15 Aug 2012:
Wildlife Vanishing in Brazil’s
Fragmented Atlantic Forest, Study Says
The fragmentation of tropical forests in eastern Brazil as a result of agricultural expansion and other human activities has decimated biodiversity even within the pockets of forest that still remain, a new study has found
. Using wildlife surveys and interviews conducted at 196 forest fragments across a 253,000-
Edson Grandisoli/ Jaguar Conservation Fund
square-kilometer region inside Brazil’s Atlantic Forest, a team of researchers estimated that only about 22 percent of the animals that once inhabited the region are still there — far lower than earlier estimates
. According to their findings, published in the journal PLoS ONE
, white-lipped peccaries have been “completely wiped out,” while jaguars, lowland tapirs, woolly spider-monkeys and giant anteaters are essentially extinct. The loss of wildlife has even extended to areas where forest canopies are still relatively intact, said Carlos Peres, an ecologist at the University of East Anglia and lead author of the study. While the Atlantic Forest once covered more than 1.5 million square kilometers, about 90 percent of that area has been cleared for agriculture, pasture, or urban expansion. Most of the remaining patches of forest, researchers say, are about the size of a football field.
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Watch the video. | <urn:uuid:fd9b46a7-44f8-4d08-ab3b-0be66b610aa1> | 3.140625 | 543 | Truncated | Science & Tech. | 26.065364 |
has the same result as us--
, but when it is used in a comparison, the --
means that C will decrement the value FIRST, before the comparison, while --
means that C will decrement the value AFTER the comparison. If you use it us--;
alone, both give the same result. You may say why the creators of C placed such ambiguous operations in the language. Well, once you learn it deeply, it is a language that allows you to write a very compact and intelligently optimized code. 20 years ago, there used to be C programming contests, where you could do very very complex things in just one line of code. Of course the resulting code was write only, and not meant to be read by mere mortals.
I consider wiring implementation of delayMicroseconds() a bug... the programmer should have used
if (us-- <= 1)
Probably he/she assumed that nobody wants to invoke a delay routine to wait 0 units of time... but it was a wrong assumption after all. | <urn:uuid:9c4e55ce-f9b5-4b02-9760-59fb8bd5e497> | 2.984375 | 212 | Comment Section | Software Dev. | 59.264505 |
Manual Section... (2) - page: fallocate
NAMEfallocate - manipulate file space
#define _GNU_SOURCE #include <fcntl.h> int fallocate(int fd, int mode, off_t offset, off_t len);
DESCRIPTIONThis is a nonportable, Linux-specific system call. For the portable, POSIX.1-specified method of ensuring that space is allocated for a file, see posix_fallocate().
fallocate() allows the caller to directly manipulate the allocated disk space for the file referred to by fd for the byte range starting at offset and continuing for len bytes.
The mode argument determines the operation to be performed on the given range. Currently only one flag is supported for mode:
- This flag allocates and initializes to zero the disk space within the range specified by offset and len. After a successful call, subsequent writes into this range are guaranteed not to fail because of lack of disk space. Preallocating zeroed blocks beyond the end of the file is useful for optimizing append workloads. Preallocating blocks does not change the file size (as reported by stat(2)) even if it is less than offset+len.
If FALLOC_FL_KEEP_SIZE flag is not specified in mode, the default behavior is almost same as when this flag is specified. The only difference is that on success, the file size will be changed if offset + len is greater than the file size. This default behavior closely resembles the behavior of the posix_fallocate(3) library function, and is intended as a method of optimally implementing that function.
RETURN VALUEfallocate() returns zero on success, and -1 on failure.
- fd is not a valid file descriptor, or is not opened for writing.
- offset+len exceeds the maximum file size.
- A signal was caught during execution.
- offset was less than 0, or len was less than or equal to 0.
- An I/O error occurred while reading from or writing to a file system.
- fd does not refer to a regular file or a directory. (If fd is a pipe or FIFO, a different error results.)
- There is not enough space left on the device containing the file referred to by fd.
- The file system containing the file referred to by fd does not support this operation.
- The mode is not supported by the file system containing the file referred to by fd.
VERSIONSfallocate() is available on Linux since kernel 2.6.23. Support is provided by glibc since version 2.10.
CONFORMING TOfallocate() is Linux-specific.
SEE ALSOftruncate(2), posix_fadvise(3), posix_fallocate(3)
COLOPHONThis page is part of release 3.24 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.
This document was created by man2html, using the manual pages.
Time: 15:26:29 GMT, June 11, 2010 | <urn:uuid:023f9339-fb34-405b-a5c6-6e3fe83fbcb3> | 2.953125 | 681 | Documentation | Software Dev. | 51.575518 |
A lot of energy, yes, but for a very short period of time.
Given that the cost of the entire prototype program is vastly less than the cost of a Shuttle launch, it is safe to assume(!) that the per-kilo cost to orbit is substantially less via railgun.
In addition, given that the payload is launched by a single initial impulse rather than a long, slow burn, the mass fraction is much higher. You are not using energy to lift a bunch of fuel to provide energy to lift a bunch of fuel to provide, etc., etc. to lift the payload into orbit, you are simply lifting the payload into orbit.
Viable payloads for this technology include food, water, fuel, oxygen, metal, plastic. With appropriate facilities in orbit, these things can then be assembled into useful and interesting devices. If all we have to do is lift astronauts and sensitive components via Shuttle (or Proton rocket or Dragon capsule or whatever), then we can save billions on launch costs while exploring our solar system. | <urn:uuid:560985c9-4fde-4632-9baf-822f8a9da3ff> | 2.765625 | 211 | Comment Section | Science & Tech. | 52.262214 |
Additional CO2 and warmer weather will help plants, the climate change denialists say. That’s not what we see, however. Turns out CO2 helps weeds, and warmer weather helps destructive species, more than it helps the stuff we need and want in the wild.
For example, the white-bark pine, Pinus albicaulis:
From American Forests:
With increasingly warm winters at high elevations in the West, a predator that has stalked forests for decades has gained the upper hand. It is mountain pine blister rust, an invasive fungus. Combined with mountain pine beetles, which kill hundreds of thousands of trees per year in the Greater Yellowstone Area (GYA), the environmental health of the Rocky Mountains and neighboring regions is in danger. To make matters worse, the species most susceptible to these two threats, the whitebark pine, is also the most vital to ecosystem stability, essential to the survival of more than 190 plant and animal species in Yellowstone alone.
First debuted at SXSW Eco, this video tells the story of our endangered western forests and how American Forests and the Greater Yellowstone Coordinating Committee are working toward their restoration and protection for future generations.
- Wyoming study delves into pine’s impact on grizzlies (billingsgazette.com)
- Exxon Facing New Lawsuit over Yellowstone Spill (insurancejournal.com)
- Matt Martin: Wildlife surprises abound at Yellowstone (goerie.com)
- Exxon Hit With New Lawsuit Over Yellowstone Spill (insurancejournal.com)
- Oce Collaborates with Michelin to Help Preserve a National Treasure (prnewswire.com) | <urn:uuid:7a862ec8-fbd4-4ec8-98e3-f6a0d406a145> | 3.15625 | 346 | Personal Blog | Science & Tech. | 34.533411 |
How fast are larval fishes?
Contrary to a previously held notion that larval (baby) fishes are at the mercy of ocean currents, many larval reef fishes are in fact very strong swimmers and can swim surprisingly fast.
The average 1cm long fish larva swims at 20 cm/sec (14 body lengths/sec). To put these figures into perspective, if Olympic swimmers could swim as well as fish larvae, they could do the 100 m in 3.6 seconds. The world record is about 48 seconds.
Reef-fish larvae also have amazing endurance. The average reef-fish can swim in a laboratory tread-mill, without rest or food, for several days covering about 40 km. Scaled to size, this is equivalent to a human swimming about 4000km.
- View information on Dr Jeff Leis' research on larval fishes.
Mark McGrouther , Collection Manager, Ichthyology | <urn:uuid:39d893f6-63b9-4d9c-b740-cf22c268a823> | 3.203125 | 191 | Knowledge Article | Science & Tech. | 63.5235 |
Late Thursday night, we finally received our first marine sediment core, in the form of a Jumbo Kasten Core from the Vega Drift. For Professor McCormick’s marine microbiology team this meant the start of a long couple of days. The first deployment of the Kasten Core equipment by the Marine Technicians, resulted in a core that was only about a meter and half in length. Since the Jumbo Kasten Core can potentially produce a core 6 meters in length, this short one was considered bad to sample. However with a second deployment, we were able to get a core 4.3 meters long. With the help of many people, the Kasten Core was carried into the Aft Dry Lab and laid down along a very long table. This is where the sampling began.
As we opened up the side of the metal frame surrounding the core, panel by panel, the smell of sulfur emanated into the lab as well as the hallway. To most people the smell of rotten eggs would repulse them, but for our group it was exciting because we are looking to identify microbes that use different forms of sulfur to respire. We quickly got to work using 60 milliliter syringes to collect large amounts of the sediment at thirty different locations down the core. With a tape measure lying next to the long sediment core, each centimeter down the length of it, represented a centimeter deep into the sediment. We took samples at thirty different depths because we are interested in how the microbial community structure changes the deeper you go into the sediment. We also collected a second set of sediment at the same depths to investigate the geochemistry of the pore water, which was separated from the sediment using a centrifuge. We hope to determine what kind of levels of methane, sulfide, sulfate, iron, and many other elements exist at the different depths. One of the goals of this project is to potentially hypothesize why certain microbes are found at some depths and not others using the geochemistry and other information we already know. By the end of the trip we should have samples from several different Jumbo Kasten Cores from several different locations along the Antarctic Peninsula.
During the night shift, 12 a.m. to 12 p.m, we completed our journey through the Bransfield Strait. By 6 a.m., we had entered the Antarctic Sound. The sunrise was cloudy, and fog descended soon after, but we were able to catch a glimpse of Joinville Island to the east and the continent to the west of the ship.
The marine geology students took regular trips to the deck every half hour or so by in hopes of being the first to spot ice. Not long after arriving in the sound, we set up station. Our first deployment of the cruise began at 7:42 a.m. as we released a Conductivity Temperature Depth profiler (CTD), and everyone was happy to receive water samples from the instrument and move on to the next project. By noon, we had released another CTD and were troubleshooting a few whale bone lander issues. By the time the night shifters were off, we were on our way to the Vega Drift, a site further south where we intend to collect a jumbo Kasten core. If we are successful, we will be sampling this core for the next 24 hours or so. It’s difficult to leave the lab and climb into bed on this first day of sampling and icy scenery.
We are now three days out of port and have entered the Drake Passage. We were informed before leaving Punta Arenas that this passage had some of the roughest waters in the world, but, so far we've encountered very little pitching or rolling.
For the past week, Liz and I worked with Professor McCormick to set up our lab. Most importantly, we set up an anoxic glove box that we will use to divide up sediment cores for sampling. This task proved to be particularly difficult because we needed to ensure that the container was airtight. Anoxic conditions are ideal for the bacteria we are researching.
Yesterday we received a tutorial on how to load and unload the megacore tubes used for sampling. The marine techs brought out two megacore casings and demonstrated the proper way to load them so that the mechanism closes properly once it reaches the ocean floor. There are twelve casings in one drop for a megacore, so we will have our hands full with both loading and carefully unloading them without disturbing the samples. Once our group has selected an optimal core for sampling, we will take several chemical readings from the sediment. We will also bring samples back to Hamilton to propagate bacteria.
054 14.9290 S
065 29.4548 W
With the recovery of the whale bone lander in the Antarctic Sound three and a half days away, the scientists aboard the Nathaniel B. Palmer are making ready equipment for the deployments to follow. Unfortunately, a bout of rough seas in the Straits has put a few members of our stalwart party out of commission.
High wind and waves made sleeping difficult last night for those of us on day watch (noon to midnight), but I can’t help but feel sorrier for my peers on the night watch (midnight to noon). They’ve been adjusting their sleep schedules over the past three days to wake up at 11 p.m. and work through the night until lunch. The changes will be easier to deal with once we reach Antarctica and the seas are calmed by ice.
Today we started the normal duties associated with the watches. Nadine Orejola, a student from Montclair State University, and I are keeping track of the multitude of numbers blinking at us from monitors in the ‘forward dry lab.’ This is lab closest to the bow of the boat. As our watch chief Julia Wellner, a professor at University of Houston, explains, we are responsible for recording data including latitude, longitude, speed and heading (360º compass direction), and water depth. Time and date are other matters. Instead of recording the local time, we record GMT (Greenwich Mean Time), which is three hours ahead of current local time, and the Julian Day (today is Julian Day 072). These numbers standardize data comparison, especially in case the time zone changes. We are also charged with recording the gravity in our area, which changes according to one’s location. We also record air and water temperatures, wind direction and speed, and barometric pressure. These readings are but a few of those available to us from shipboard instrumentation.
As our watch-mates recover from seasickness and we make it through the Drake Passage to our field area, we will all take on the many responsibilities of watch-standing. For now, Nadine and I are hanging out in the forward dry lab, waiting for the seas to calm.
We’re on our way! After a couple days of delays, we have finally made our way east along the Straits of Magellan to the South Atlantic Ocean. From there, we will be heading due south through the choppy waters of the Drake Passage. Our field area is the northeastern Antarctic Peninsula, where we’ll be starting operations in about three days.
First on the agenda is a project that has everyone simultaneously excited and a little squeamish. The diversity of deep sea floor organisms is amazingly complex, and perhaps the most unique site of organism diversification is on the decaying bodies of massive whales. It’s easiest to think of these whales on the seafloor like decaying trees in a forest. As trees decay, they progress through multiple stages during which specific varieties of insects and fungi pick away at the wood. Whale carcasses are very similar, and while the seafloor may look like an expansive, empty plain, the seafloor around the Antarctic Peninsula is loaded with nutritious sediment. Whale bones, unlike decaying trees, actually seem to host organisms that only live on the bones, and nowhere else. Even more interesting, organisms are not unlike those that inhabit the area around deep sea vents: tubeworms, amphipods (e.g. pillbugs), and sea spiders.
Craig Smith, of the University of Hawaii, and David Honig of Duke University are heading up the whale bone project. Deployed two years ago, the “whale bone lander” is a large rectangular frame, with baskets on either side that hold the large whale bones that were left on the sea floor during our previous LARISSA cruise, NBP10-01. Two years later, we’re back to pick up the lander and sample the whale bones. An acoustic release mechanism, after receiving a signal from the Palmer, will release the lander. Everyone who’s experienced the whale bones in the past agrees, while the organisms are fascinating, the bones themselves issue a pungent odor that’s not easy to remove from clothing. That being said, I think we’re still pretty excited to pick some worms from decayed whale bone!
The LARISSA project (LARsen Ice Shelf System, Antarctica), part of the National Science Foundation’s Antarctic Integrated Systems Science department, was initiated in 2007. Scientific research in remote environments like Antarctica is especially difficult and expensive. However, advantageous collaborations such as LARISSA allow geologists and biologists from a diversity of institutions to facilitate efficient multi-disciplinary study. This variety of new-age exploration grants scientists greater capacity to focus on specific topics, while also receiving input from their peers. LARISSA was developed in response to the collapse of the Larsen B Ice Shelf in 2002 as a way to discover as much as possible about the newly exposed area. Our current voyage encompasses a diversity of institutions and nationalities. Fourteen institutions and seven countries are represented amongst the scientists alone. Three specialized groups compose the LARISSA project: Marine & Quaternary Geology, Marine Ecosystems, and Cryosphere & Oceans. Each group is devoted in part to determining the mechanisms of the ice shelf’s collapse, as well as the consequences to previously covered ecosystems. Other projects involve the geological and biological processes of the Antarctica Peninsula.
Before we can even cross the Drake Passage, the stretch of water separating South America and Antarctica, we must leave the Straits of Magellan, which is the natural channel that made Punta Arenas a booming port town before the construction of the Panama Canal. Ferdinand Magellan, for whom the Straits are named, is one of the names most synonymous with exploration in western history. A Portuguese explorer with ample funding from the Spanish monarchy, his fleet of ships set out to circumnavigate the world in August of 1519. Although he was killed in a mutinous uprising in the Philippines before he could complete the voyage, Magellan managed to discover an alternate route to the treacherous Cape Horn below South America: the Strait of Magellan. Although the days of blazing new routes around little-explored continents have passed, there are still mysteries to be uncovered in the far-flung reaches of the world.
It is disconcerting to begin a six-week sojourn to one of the most mysterious places on Earth and leave the familiarity of Syracuse’s small international airport. As we traveled south from the wintry northeast, it quickly became apparent that our fellow scientists, heading to the Research Vessel Nathaniel V. Palmer, were coming from all corners of the world. After thirty six hours of travel (and a very long stopover in Santiago), we finally arrived in Punta Arenas, Chile. The excitement of customs was nothing compared to our growing jitters the following morning while walking through the city’s beautiful streets. A cosmopolitan port town, Punta Arenas was once the hub of trade and transportation at the bottom of the world. Now, its extreme southern latitude serves climate scientists, geologists, and biologists as a stopping-off point before they head to remote Antarctica.
A buff and blue team of six: two professors, one alumna, and three undergraduates, we are a small part of the scientific team aboard the Palmer. Professors Michael McCormick and Eugene Domack study biology and geology, respectively. Andrew Seraichick ’13 and Liz Bucceri ’11 will be working under Professor McCormick for the duration of the voyage, studying microbial community structures in different environments around the Antarctic Peninsula. They will be answering general, but vital, questions about these communities: who is living in these communities, and what allows them to survive in harsh Antarctic waters.
Natalie Elking ’12 and Manique Talaia-Murray ’12 are Geoscience majors working under the direction of Professor Domack. They will be heavily involved with the collection and ship-board analysis of offshore sediment cores, as well as a brief excursion ashore to Robertson Island to collect granite samples that will help establish a chronology for land ice extent on Antarctica from before the last glacial maximum (~12 000 years ago).
On March 5, we convened in the massive NSF LARISSA warehouse to collect our cold weather gear, including Carhart overalls, steel-toed rubber work boots, and massive red down parkas affectionately termed ‘Big Reds.’ The following day we boarded the ship, stowed our gear in our small, but well-proportioned berths, and got ready for a tempestuous voyage across the Drake Passage. | <urn:uuid:7f526e83-488c-4ac4-80f4-19db1af438ad> | 3.296875 | 2,776 | Personal Blog | Science & Tech. | 44.267204 |
Proc and Lambda are used to create code blocks. After creating them, we can pass them around our code, just like variables.
But there are 2 significant differences we have to keep in mind.
1. Suppose a Proc or a lambda is used to create a code block inside of a method. If the Proc/Lambda has a return statement inside of its code, in the case of Proc, the whole method is returned. But in the case of Lambda, its not. The execution continues to any further statements inside the method. Here is the code fragment that explains this difference.
2. A Proc will not check if the arguments are passed to it are of the same number as its parameters. A Lambda will throw an error if we violate the number of parmeters.
You see, Proc is very naughty :) It won't check for the number of arguments and it will return without the permission of the method in which it resides!
Earlier when I started programming using ruby (system ruby), it was all clean. I used to install gems with sudo gem install somegem . Then came rvm and it asked me to install gems without sudo like: gem install somegem. Then came bundler, which asked me to install gems by bundle install.
Since then, I was confused about how things work using these 2 tools on top of ruby. Well, I decided to put an end to that confusion and here is how they work.
When you use
rubygems would install that gem in the place defined by $GEM_HOME environment variable. Now this is the variable that dominates where rvm puts gems in and where bundler puts gems in.
I suppose you are using rvm to manage multiple rubies. When you switch rubies using rvm, the $GEM_HOME variable changes. rvm changes it.
When we use bundler install to manage dependencies, bundler simply call gem install under hood for each of the gems defined in Gemfile. Lets see this in terminal.
First create a new rails project, it comes with a Gemfile.
Lets then create a new gemset for this project and use it
Install bundler and check $GEM_HOME location for any gems installed.
Do a bundle install in this project and check $GEM_HOME again. | <urn:uuid:a3e76f23-6553-4b02-aa53-776b7e4a9822> | 3.546875 | 481 | Personal Blog | Software Dev. | 63.261751 |
chemistry question #88
Nick Hiebert, a 23 year old male from the Internet asks on November 14, 1999,Q:
Is there a substance known to science that reacts to electrical impulses by contracting or changing its density?
viewed 12715 times
There may be many such things. One thing I'm aware of are piezoelectric materials that do this: salts, ceramics, and plastics. The chief polymer used for this is Polyvinylidene Fluoride (PVDF). If you do web searches on this, you will find much info. A good explanation can be found at http://www.ndt.net/article/yosi/yosi.htm
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