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A decomposition reaction is the opposite
of a synthesis reaction. In a decomposition reaction a reactant compound
is broken into two or more less complex substances. you are given a compound
as the reactant. In most cases, to find the product you split the compound
into the individual elements. The other types of decomposition reactions
(decomposition of a hydrate, chlorate, carbonate, etc.) are covered in other
tutorials. This tutorial focuses on the decomposition of a binary compound.
The general pattern of a decomposition reaction is:
AB --> A + B
Look at the example below.
--> 2H2(g) +
Water decomposes (usually
with the help of electricity) to form hydrogen gas and oxygen gas. Hydrogen
and oxygen are written with subscripts of 2 because they are both diatomic
let’s go step by step.
Predict the products when solid iron(II) oxide decomposes.
|1. Write the formula for the given reactant.
|2. On the products side of the equation, write
the symbols for the two elements in the compound. Be
sure to separate the elements by a + sign. If either of the elements
is diatomic, be sure to write a 2 as its subscript.
||FeO(s) --> Fe(s) +
Oxygen is diatomic, so it is written with a subscript
|3. Balance the equation.
||2FeO(s) --> 2Fe(s) | <urn:uuid:fdcf8142-8dd9-466b-a482-89bc054593db> | 4.375 | 324 | Tutorial | Science & Tech. | 53.844643 | 2,100 |
Sep. 10, 2009 Much of circumpolar Arctic research focuses on the physical, direct changes resulting from climate warming such as sea ice retreat and temperature increases. “What’s understudied is the living component of the Arctic and that includes humans,” said Syndonia “Donie” Bret-Harte, associate professor of biology at the University of Alaska Fairbanks and co-author of a paper to be published September 11, 2009 in the journal Science.
The paper reviews current knowledge on the ecological consequences of climate change on the circumpolar Arctic and issues a call for action in several areas of global climate change research.
“Humans live in the Arctic with plants and animals and we care about the ecosystem services such as filtering water, fiber and food production and cultural values that the Arctic provides” said Bret-Harte, who specializes in Arctic plant ecology in Alaska.
The global average surface temperature has increased by 0.72 F (0.4 C) over the past 150 years and the average Arctic temperature is expected to increase by 6 C. “That’s a mind bogglingly large change to contemplate and keep in mind that no one lives at the average temperature,” Bret-Harte said.
The international team of scientists who collaborated on this paper reviewed dozens of research documents on the effects of circumpolar Arctic warming. They note that numerous direct effects including lengthening of growing season following a rapid spring melt, earlier plant flowering and appearance of insects following a warmer spring, deaths of newborn seal pups following melting of their under-snow birthing chambers have other, often more subtle, indirect effects on plants, animals and humans that warrants increased attention.
Understanding how changes in plant and animal populations affect each other and how they affect the physical or nonliving components of the Arctic is critical to understanding how climate warming will change the Arctic.
One effect studied intensively at the UAF Institute of Arctic Biology Toolik Field Station on Alaska’s North Slope is shrub expansion on the tundra.
“Shrubs are increasing on the tundra as the climate warms and more shrubs will lead to more warming in the spring,” said Bret-Harte. Snow reflects most incoming radiation, which is simply light that can transfer heat. Shrubs that stick out of the snow in spring absorb radiation and give off heat. In this positive feedback cycle, the heating of the air immediately above the snow warms the snow, causing it to melt sooner. Warmer soils lead to increased nutrient availability, which contributes to greater shrub growth, which then contributes to still more warming.
Another effect studied intensively in Alaska occurs under the snow.
“We need to better understand how winter comes and goes and how that drives shifts in plant-animal interactions,” said Jeff Welker, professor of biology at the University of Alaska Anchorage. When it didn’t snow at Toolik Field Station until Thanksgiving a few years ago the soil got cold and stayed cold. So cold that microbes in the soil were barely active. The spring green-up was slow in coming and likely affected caribou forage," says Welker.
In 2008, the snow started falling in September and never quit. The warmer winter soils with their active microbes were insulated from the cold and were able to provide nutrients to plants that stimulated growth.
The authors call for immediate attention to the conservation of Arctic ecosystems; understanding the ecology of Arctic winters; understanding extreme events such as wildfires and extended droughts; and the need for more baseline studies to improve predictions.
“This paper identifies gaps in our knowledge, what we need to be doing and where the public needs to spend its money,” said Welker.
The research team was led by Eric Post, Penn State University, and included biologists, ecologists, geographers, botanists, anthropologists, and fish and wildlife experts from the University of Alberta and the Canadian Wildlife Service in Canada; Aarhus University and the University of Copenhagen in Denmark; the University of Helsinki in Finland; the Arctic Ecology Research Group in France; the Greenland Institute of Natural Resources in Greenland; the University Centre on Svalbard, the University of Tromsø, and the Centre for Saami Studies in Norway; the University of Aberdeen and the University of Stirling in Scotland; Lund University and the Abisko Scientific Research Station in Sweden; the University of Sheffield in the UK; and the Institute of Arctic Biology and the U.S. Geological Survey at the University of Alaska Fairbanks, the Environment and Natural Resources Institute of the University of Alaska Anchorage, and the University of Washington in the United States.
Support was provided by Aarhus University, The Danish Polar Center, and the U.S. National Science Foundation.
Other social bookmarking and sharing tools:
- Eric Post, Mads C. Forchhammer, M. Syndonia Bret-Harte, Terry V. Callaghan, Torben R. Christensen, Bo Elberling, Anthony D. Fox, Olivier Gilg, David S. Hik, Toke T. Høye, Rolf A. Ims, Erik Jeppesen, David R. Klein, Jesper Madsen, A. David McGuire, Søren Rysgaard, Daniel E. Schindler, Ian Stirling, Mikkel P. Tamstorf, Nicholas J.C. Tyler, Rene van der Wal, Jeffrey Welker, Philip A. Wookey, Niels Martin Schmidt, and Peter Aastrup. Ecological Dynamics Across the Arctic Associated with Recent Climate Change. Science, 11 September 2009: 1355-1358 DOI: 10.1126/science.1173113
Note: If no author is given, the source is cited instead. | <urn:uuid:dedf12b5-c163-4266-9e92-29e7a160f76d> | 3.84375 | 1,203 | News (Org.) | Science & Tech. | 40.009782 | 2,101 |
Observe the power of the Sun first-hand
Make the principles of solar power come alive for young scientists. Learn about how solar cells convert energy from sunlight into mechanical energy with this kit’s unique single-piece solar motor, composed of a photovoltaic cell and an electric motor.
You’ll build and power more than 20 solar-powered models, including cars, trucks, planes, windmills, waterwheels, robots, and other vehicles. Use them to experiment with the solar cell and observe how different placement angles, different light levels, different sources of light, and different loads affect its operation.
Includes solar cell, 20 experiments, and step-by-step instructions.
Recommended for ages 8+.
WARNING! — This set contains chemicals and parts that may be harmful if misused. Read cautions on individual containers and in manual carefully. Not to be used by children except under adult supervision. | <urn:uuid:83fcb38c-09a1-4f2a-85f7-762202cbdcde> | 3.859375 | 191 | Product Page | Science & Tech. | 42.643577 | 2,102 |
Using the European Herschel space telescope, an international team including astronomers at Observatoire de Paris, Institut de Radio Astronomie Millimetrique and Observatoire de Grenoble in France observed hot water vapor formed somewhere that was previously thought to be impossible: deep into the atmosphere of a red giant pulsating carbon star, CW Leonis. This result, published in the 2 September 2010 issue of Nature magazine, should help to understand how this type of evolved star produces and expels key ingredients for all known forms of life.
The major building blocks of life on Earth are water and carbon-based molecules, synthesized in large quantities by stars like the Sun at the end of their lives. When they age, these stars become red giants and puff out their atmospheres. These have previously been seen to contain either water or carbon-based molecules, and it was thought that these two types of species could not co-exist. New results from the Photodetector Array Camera Spectrometer PACS and Spectral and Photometric Imaging Receiver SPIRE onboard the European Space Agency ESA Herschel observatory, launched in May 2009, have overturned this longstanding concept by detecting abundant hot water vapor in the atmosphere of a very carbon-rich red giant star.
CW Leo (catalogued IRC+10216) is a red giant pulsating star in the constellation of Leo. With a mass roughly similar to that of the Sun, it has expanded to hundreds of times the size of our own star -- if placed in the Solar System it would extend beyond the orbit of Mars. Barely detectable in the visible, even by the largest telescopes, it is the brightest star in the sky observed in the infrared, at wavelengths ten times longer than those seen by human eyes. This suggests that huge quantities of dust particles have condensed around the star. They absorb almost all of its visible radiation and re-emit it in the infrared.
The star is classified as a 'carbon-star' and, at a distance of around 500 light-years, it is the closest such object to Earth. Nuclear fusion reactions deep inside are converting helium into carbon. The star is currently emitting ten thousand times as much energy as the Sun. And its outer layers are billowing out in a 'stellar wind' -- a billion times more intense than the solar wind. This matter is rich in many different carbon based molecules and dust particles. CW Leonis will soon end its life by becoming a hot white dwarf star surrounded by a diffuse planetary nebula -- an extended cloud of gas and dust made up of material presently in its atmosphere and expelled into space afterwards.
With so much carbon in its atmosphere, almost all of the oxygen should be locked up in carbon monoxide CO, say scientists. There should be no water vapor, H2O. However, in 2001 the Submillimeter Wave Astronomy Satellite SWAS detected emission from CW Leonis at a wavelength of water vapor. A possible proposed origin was that the wind was releasing water molecules from a cloud of evaporating icy comets around the star.
However, now, Herschel has detected the definitive signature of water at many more wavelengths. Vapor appears at temperatures of up to 1000 degrees, implying that it is distributed throughout and deep down into the wind. The model of the stellar wind interacting with a distant icy comet cloud must now be replaced by another one in which water vapor is created by previously unsuspected chemical reactions triggered with help from interstellar ultraviolet radiation. Ultraviolet light breaks up the carbon monoxide, releasing oxygen atoms that can then react with hydrogen to form water molecules.
The only possible source of the ultraviolet light is interstellar space. It was already known that the stellar wind is 'clumpy', and the Herschel results have shown that some regions around the star must be almost empty. These allow the ultraviolet light to reach the deepest layers of the atmosphere and initiate chemical reactions to produce water.
On primitive Earth, harsh ultraviolet radiation from the Sun may have played a crucial role in triggering prebiotic processes that ultimately created the molecular building blocks of life. New Herschel results imply that analogous processes operate around red giant stars that supply material for new generations of stars and planets in galaxies like our Milky Way.
# # #
This news is based on a scientific paper entitled "Warm water vapour in the sooty ouflow from a luminous carbon star," published on Thursday, 2 September 2010, in Nature.
This work was conducted by 37 scientists from 8 countries. The lead author is Leen Decin from Katholieke Universteit Leuven (Belgium). Marcelino Agundez at Observatoire de Paris, Michel Guelin at Institut de Radio Astronomie Millimetrique IRAM and Claudine Kahane at Observatoire de Grenoble contributed in France.
Marcelino Agundez is at Laboratoire Univers et Theories LUTH, a common research unity between Observatoire de Paris, CNRS and Universite Paris-Diderot.
IRAM is a French, German and Spanish institute supported in France by INSU/CNRS.
Herschel is an ESA observatory. PACS and SPIRE instruments have been developed by a consortium of institutes with support from CEA, CNES, CNRS funding agencies in France. | <urn:uuid:a576ae02-946e-4faf-a24d-5b1b34cc9737> | 3.90625 | 1,089 | Knowledge Article | Science & Tech. | 33.993289 | 2,103 |
by Staff Writers
Eindhoven, Netherlands (SPX) Jan 23, 2013
Researchers at Eindhoven University of Technology (TU/e) together with researchers at the Hong Kong Polytechnic University (PolyU), have developed a special treatment for cotton fabric that allows the cotton to absorb exceptional amounts of water from misty air: 340 % of its own weight.
What makes this 'coated cotton' so interesting is that the cotton releases the collected water by itself, as it gets warmer. This property makes of the coated cotton materials a potential solution to provide water to the desert regions, for example for agricultural purposes. The results of this research will be published next month in the scientific journal Advanced Materials.
The researchers applied a coating of PNIPAAm, a polymer, to the cotton fabric. At lower temperatures, this cotton has a sponge-like structure at microscopic level.
Up to a temperature of 34C it is highly hydrophilic, in other words it absorbs water strongly. Through this property the cotton can absorb 340 % of its own weight of water from misty air - compared with only 18% without the PNIPAAm coating.
In contrast, once the temperature raises the material becomes hydrophobic or water-repellant, and above 34C the structure of the PNIPAAm-coated Beetles in desert areas can collect and drink water from fogs, by capturing water droplets on their bodies, which roll into their mouths.
Similarly, some spiders capture humidity on their silk network. This was the inspiration for this new coated-cotton material, which collects and releases water from misty environments simply as the temperature changes throughout the day.
This property implies that the material may potentially be suitable for providing water in deserts or mountain regions, where the air is often misty at night. According to TU/e researcher dr.
Catarina Esteves a further advantage is that the basic material - cotton fabric - is cheap and can be easily and locally produced. The polymer coating increases the cost slightly, but with the current conditions the amount required is only about 12%. In addition, the polymer used is not particularly costly.
Fine-mesh 'fog harvesting nets' are already being used in some mountains and dry coastal areas, but these use a different principle: they collect water from misty air, by droplets that gradually form on the nets and fall to the ground or a suitable recipient. But this system depends on a strong air flow, wind. The coated cotton developed the research team can also work without wind.
In addition, cotton fibers coated with this polymer can be laid directly where the water is needed, for example on cultivated soil. The researchers are also considering completely different applications such as camping tents that collect water at night, or sportswear that keeps perspiring athletes dry.
The research was led by professor John Xin at PolyU and dr. Catarina Esteves at TU/e. They now intend to investigate further how they can optimize the quality of the new material.
For example they hope to increase the amount of water absorbed by the coated-cotton. Moreover they also expect to be able to adjust the temperature at which the material changes from water-collecting to the water-releasing state, towards lower temperatures.
Eindhoven University of Technology
Water News - Science, Technology and Politics
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement| | <urn:uuid:6830e399-c66e-4ed8-be74-74da9d93fafc> | 3.21875 | 823 | News Article | Science & Tech. | 34.031412 | 2,104 |
Has global warming slowed right down?
Global warming could be a lot less extreme than feared, according to a new study which finds that worldwide temperatures have levelled off.
"These results are truly sensational," says Dr Caroline Leck of Stockholm University, who wasn't involved in the research. "If confirmed by other studies, this could have far-reaching impacts on efforts to achieve the political targets for climate."
According to the Norwegian team, while Earth's mean surface temperature climbed sharply through the 1990s, this increase has levelled off nearly completely at its 2000 level. Ocean warming also appears to have stabilised somewhat, despite the fact that CO2 and other emissions are still on the rise.
The Intergovernmental Panel on Climate Change (IPCC) predicts that the result of doubled atmospheric CO2 levels would probably be between 2°C and 4.5°C. The new study, however, gives a figure of 1.9°C as the most likely level of warming.
"In our project we have worked on finding out the overall effect of all known feedback mechanisms," says project manager Terje Berntsen of the University of Oslo.
"We used a method that enables us to view the entire earth as one giant 'laboratory' where humankind has been conducting a collective experiment through our emissions of greenhouse gases and particulates, deforestation, and other activities that affect climate."
The team entered all the factors contributing to human-induced climate forcings since 1750 into their model, along with fluctuations in climate caused by natural factors such as volcanic eruptions and solar activity. They also entered measurements of temperatures taken in the air, on ground, and in the oceans.
When they applied their model and statistics to analyse temperature readings from the air and ocean for the period ending in 2000, they found that climate sensitivity to a doubling of atmospheric CO2 concentration would most likely be 3.7°C - somewhat higher than the IPCC prognosis.
But the researchers were surprised when they entered temperatures and other data from 2000-2010, finding that climate sensitivity was greatly reduced to just 1.9°C.
"The Earth's mean temperature rose sharply during the 1990s. This may have caused us to overestimate climate sensitivity," says Berntsen.
"We are most likely witnessing natural fluctuations in the climate system - changes that can occur over several decades - and which are coming on top of a long-term warming. The natural changes resulted in a rapid global temperature rise in the 1990s, whereas the natural variations between 2000 and 2010 may have resulted in the levelling off we are observing now."
Berntsen emphasises that the findings mustn't lead to complacency. But, he says, they indicate that it may be more feasible to achieve global climate targets than previously thought. | <urn:uuid:2f488b94-16cb-4638-88ba-02da104925c3> | 3.5 | 571 | News Article | Science & Tech. | 38.779094 | 2,105 |
- By Eric Taber
- July 15, 2012
We’ve entered crunch time, with students and PIs working feverishly to collect data as the end of our time in Siberia quickly approaches. Today, Lindsey Parkinson (Western Washington University) and I spent the afternoon in the field measuring carbon flux on various vegetation types. Carbon flux refers to the uptake of CO2 (photosynthesis) and release of CO2 (respiration). Vegetation can influence carbon flux in a number of ways. First, soil moisture, temperature and active layer depth all vary with vegetation type and these factors influence microbial activity and hence respiration and CO2 release. Additionally, plant functional types vary in their photosynthetic rate (CO2 uptake) as well their respiration rate. As the storage of carbon in Arctic soils is significant, understanding the dynamics of carbon flux from soil and vegetation will inform our understanding of the global carbon cycle.
By enclosing roughly a 0.5m3 of vegetation in a clear plexiglass enclosure built by Sue Natali, I can measure changes in CO2 concentrations as soil and plants respire/photosynthesize. After plotting CO2 concentration with time, the slope of a best fit line translates into the rate of CO2 flux, either positive (respiration exceeds photosynthesis) or negative (photosynthesis exceeds respiration). I’m interested in differences in carbon flux between vegetation types and am measuring flux in both high and low density larch forests with future hopes to scale up my flux measurements to a larger spatial scale with a larch density biomass map that was created previously be Polaris Participants.
Additionally, to better understand how vegetation type influences carbon flux, Mike Loranty (also of Colgate University) and I are using a technique called electrical resistivity imaging to look at soil and permafrost characteristics under different vegetation types. Upon placing electrodes along a transect, we send a current through the electrodes and into the ground. Adjacent electrodes pick up this current and depending on the moisture content, temperature and other properties of the soil/permafrost, the current will vary. Based upon these variances, a computer algorithm can calculate the resistivity of the soil along a horizontal and vertical profile. So, Mike and I have been using this technique along transects that run through the three vegetation types I am focusing on – mosses, lichens, and shrubs. And we are seeing differences below ground associated with these plant functional types, particularly between lichen and non-lichen vegetation patches. Active layer depth, resistivity, and hence soil moisture content differ markedly underneath lichen and adjacent vegetation patches. These differences likely arise from below ground characteristics, moisture and temperature, which influence microbial metabolic activity and respiration or the rate at which carbon is released from the soil.
Over the coming week, I hope to gather additional flux measurements from plots along these resistivity transects and to correlate carbon flux with resistivity values as a proxy for the below ground characteristics that influence respiration rates. A great deal of work remains to be completed in the coming week but with the help of Mike, Sue and others, I am confident that it will be completed. | <urn:uuid:da03a696-e5fe-49ad-8ad7-4a08a0476f71> | 2.9375 | 652 | Personal Blog | Science & Tech. | 18.776842 | 2,106 |
Senior Thesis: Engineering a Greener Future
By Mike Cariello ‘10 & Dusty Rybovich ‘10
It is our responsibility as engineers to design a better world. Liquified Natural Gas (LNG)-carrying behemoths belch greenhouse gases across the planet, while consuming the world’s limited supply of prized and precious oil. Traditional marine diesel propulsion is ultimately an inefficient generator of electrical power — and also creates harmful emissions. We have designed an alternate propulsion plant that uses fuel cells instead of engines, and makes excellent use of the boil-off gas that naturally occurs aboard LNG carriers.
Fuel cells have been studied for centuries, but their complex nature has discouraged in-depth research until recently. Our concept plant uses a type of fuel cell already being manufactured commercially in the United States; one that is fully capable of being used at sea with LNG fuel.
When compared to LNG carriers already in operation, our system can save at least $3,000,000 per year, per ship. This savings is mostly because our vessel can make a laden voyage using only the natural boil-off gas as fuel. It also produces only 44.7% of the CO2 output, 0.033% of the NOX output, and 0.002% of the SOX output of a modern LNG carrier.
Because the technology is so new, it is unlikely to be applied in the marine industry in the very near future. However, we hope that our research will help to clarify the advantages of this revolutionary technology, and push the industry into a new age of environmental consciousness. It is our wish that through our work the industry will be inspired to allocate more resources to developing this promising idea. | <urn:uuid:d47b2f09-bc63-4ac7-b9b1-4614a396a1c8> | 3.328125 | 354 | Academic Writing | Science & Tech. | 43.453 | 2,107 |
Hydrogen: the essentials
Note that while hydrogen is normally shown at the top of the Group 1 elements in the periodic table, the term "alkaline metal" refers to the Group 1 elements from lithium downwards and not hydrogen.
Hydrogen is the lightest element. It is by far the most abundant element in the universe and makes up about about 90% of the universe by weight. It is also the most abundant element in the earth's sun.
Hydrogen as water (H2O) is absolutely essential to life and it is present in all organic compounds. Hydrogen is the lightest gas. Hydrogen gas was used in lighter-than-air balloons for transport but is far too dangerous because of the fire risk (Hindenburg). It burns in air to form only water as waste product and if hydrogen could be made on sufficient scale from other than fossil fuels then there might be a possibility of a hydrogen economy.
Hydrogen: historical information
Robert Boyle (1627-1691; English chemist and physicist) published a paper ("New experiments touching the relation betwixt flame and air") in 1671 in which he described the reaction between iron filings and dilute acids which results in the evolution of gaseous hydrogen ("inflammable solution of Mars" [iron]).
However it was only much later that it was recognized as an element by Henry Cavendish (1731-1810; an English chemist and physicist who also independently discovered nitrogen) in 1766 when he collected it over mercury and described it as "inflammable air from metals". Cavendish described accurately hydrogen's properties but thought erroneously that the gas originated from the metal rather than from the acid. Hydrogen was named by Lavoisier.
Deuterium gas (2H2, often written D2), made up from deuterium, a heavy isotope of hydrogen, was discovered in 1931 by Harold Urey, a professor of chemistry at Chicago and California (both USA).
Sometime prior to the autumn of 1803, the Englishman John Dalton was able to explain the results of some of his studies by assuming that matter is composed of atoms and that all samples of any given compound consist of the same combination of these atoms. Dalton also noted that in series of compounds, the ratios of the masses of the second element that combine with a given weight of the first element can be reduced to small whole numbers (the law of multiple proportions). This was further evidence for atoms. Dalton's theory of atoms was published by Thomas Thomson in the 3rd edition of his System of Chemistry in 1807 and in a paper about strontium oxalates published in the Philosophical Transactions. Dalton published these ideas himself in the following year in the New System of Chemical Philosophy. The symbol used by Dalton for hydrogen is shown below. [See History of Chemistry, Sir Edward Thorpe, volume 1, Watts & Co, London, 1914.]
In 1839 a British scientist Sir William Robert Grove carried out experiments on electrolysis. He used electricity to split water into hydrogen and oxygen. He then argued one should be able to reverse the electrolysis and so generate electricity from the reaction of oxygen with hydrogen. He enclosed platinum strips in separate sealed bottles, one containing hydrogen and one oxygen. When the containers were immersed in dilute sulphuric acid a current indeed flowed between the two electrodes and water was formed in the gas bottles. He linked several of these devices in series to increase the voltage produced in a gas battery. Later the term fuel cell was used by the chemists Ludwig Mond and Charles Langer.
Much later fuel cells were by NASA in the 1960s for the Apollo space missions. Fuel cells have been used for more than 100 missions in NASA spacecraft. Fuel cells are also used in submarines.
The lifting agent for the ill fated Hindenberg ballooon was hydrogen rather than the safer helium. The image below is the scene probably in a way you have not seen it before. This is a "ray-traced" image reproduced with the permission of Johannes Ewers, the artist, who won first place with this image in the March/April 1999 Internet Raytracing Competition. For details of ray-tracing you can't beat the POV-Ray site.
Hydrogen: physical properties
Hydrogen: orbital properties
Isolation: in the laboratory, small amounts of hydrogen gas may be made by the reaction of calcium hydride with water.
CaH2 + 2H2O → Ca(OH)2 + 2H2
This is quite efficient in the sense that 50% of the hydrogen produced comes from water. Another very convenient laboratory scale experiment follows Boyle's early synthesis, the reaction of iron filings with dilute sulphuric acid.
Fe + H2SO4 → FeSO4 + H2
There are many industrial methods for the production of hydrogen and that used will depend upon local factors such as the quantity required and the raw materials to hand. Two processes in use involve heating coke with steam in the water gas shift reaction or hydrocarbons such as methane with steam.
CH4 + H2O (1100°C) → CO + 3H2
C(coke) + H2O (1000°C) → CO + H2
In both these cases, further hydrogen may be made by passing the CO and steam over hot (400°C) iron oxide or cobalt oxide.
CO + H2O → CO2 + H2
WebElements now has a WebElements shop at which you can buy periodic table posters, mugs, T-shirts, games, molecular models, and more. | <urn:uuid:ef8b79b6-5ca9-4fd1-8cc8-53a10da861b7> | 3.765625 | 1,154 | Knowledge Article | Science & Tech. | 41.972782 | 2,108 |
Marine Mammal Center
oceans face an increased number of anthropogenic impacts on marine mammals and
other marine life. There are growing demands to bring together scientific
expertise, resources and technology innovation to address the effects of human
activities on marine mammals and the ecosystems on which they depend. Many of the unintentional impacts are
difficult to monitor and detect, yet they pose serious risks to marine life.
The Marine Mammal Center at WHOI uses comprehensive basic research complemented by cutting-edge technology to solve major scientific and conservation problems.
» View WHOI Marine Mammal Center Website | <urn:uuid:78de52f9-f338-4daa-a099-7a3d3a8971a0> | 2.546875 | 123 | About (Org.) | Science & Tech. | 6.404539 | 2,109 |
What's it Like at the Bottom of the Ocean?
Image courtesy of Ridge2000
On January 10, 2007, the Research Vessel Atlantis left Manzanillo, Mexico,
sailing south for 2 days to reach a site in the East Pacific Ocean. The R/V Atlantis is the support ship for the manned submersible, Alvin. Scientists on board will spend the month of January diving to the seafloor in the submersible to study the volcanic eruptions and deep-sea life along the mid-ocean ridge system.
Last year (in May 2006), scientists found extensive fresh lava at this site, evidence of recent volcanic eruptions. Most of the animals that had been living near the deep sea vents at this site were no longer there. During this research cruise, scientists are investigating whether deep sea life has returned to this area since the eruptions.
During the cruise, researchers will observe and document changes at the study site on the ocean floor. Eric Simms, co-coordinator of the SEAS (Student Experiments at Sea)
education program, is aboard the
ship. He is sending virtual postcards from sea to Windows to the Universe, describing the experience of deep sea research.
Take a look at Eric’s postcards linked below. Check back often for new postcards!
Greetings from the East Pacific Rise from Eric Simms, January 18, 2007
Volcanoes of the Deep Sea from Eric Simms, January 24, 2007
Houston, We Have a Phone Call! from Eric Simms, January 26, 2007
Diving to the Deep from Eric Simms, February 1, 2007
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This pie chart shows the relative likelihood of observing particular other species commonly observed near Junco hyemalis
These species are those which most commonly occur in our observation database near Junco hyemalis. Observations favor some phyla over others. Typically Bacteria, Fungi, Protozoa, and Arthropods are more common in the field than in our records.
This species has a large range, with an estimated global Extent of Occurrence of 10,000,000 km². It has a large global population estimated to be 260,000,000 individuals (Rich et al. 2003). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern.
Bahamas; Bermuda; Canada; Cayman Islands; Mexico; Puerto Rico; Saint Pierre and Miquelon; Turks and Caicos Islands; United States
Found in flocks in plowed fields, along roadsides, and at feeders.
List of Habitats:
1.9 Forest - Subtropical/Tropical Moist Montane
In sections below, we make some habitat inferences based on the known habitat preferences of those species most commonly associated with Junco hyemalis.
alpine, montane, temperate.
alpine meadows, boreal forest, broad-leaved forests, brush piles, brushy fence rows, canebrakes, coniferous forests, cultivated areas, deciduous woods and forests, desert, desert scrub, disturbed sites, evergreen forests, fence rows, fields, forest edges, forests, gardens, grasslands, hammocks, hardwood forests, mature forests, meadows, mediterranean-type shrubby vegetation, mesic forest, moist woods, montane forests, open forests, pasture, pine forests, rain forest, shrubby vegetation, small trees, subantarctic forest, subarctic forest, swamp forests, thickets, tropical forest, tundra grassland.
dry slopes, flood plains, hillsides, pastureland, roadsides, rock outcrops, rocky soils, sand dunes, streamsides, urban areas, valleys.
clay, limestone, loam, marl, sandy areas, sandy soil, thin soil.
along rivers, bays, bogs, brackish water, ditches, dry areas, estuaries, fens, flood plains, lagoon, lakes, marshes, mesic areas, pelagic, ponds, river banks, rivers, saltwater, shores, shrub dominated wetlands, stream banks, streams, subtidal muddy, swamps, swampy areas.
hillsides, ravines, rocky slopes. | <urn:uuid:5d874685-44d2-4acd-bc47-d62e0e617ff7> | 3.328125 | 594 | Structured Data | Science & Tech. | 27.865716 | 2,111 |
Solar Cycles Cause Global Warming & Cooling June 5, 2011Posted by honestclimate in Discussions.
Tags: climate change, global warming, solar cycles
Solar Cycles Cause Global Warming & Cooling
By Nick Anthony Fiorenza
ICECAP, June 3, 2011
Planetary warming has also been observed on Mars, Jupiter, Pluto, and on Neptune’s largest moon Triton during the decades following the peak of the “Solar Grand Maximum” – wonder why – there are no humans there! And Pluto is moving further from the sun in its orbit, thus it should be cooling, but instead it is warming. This is but one blatant indicator that suggests that the climate change on Earth is due to solar changes and our intersellar environment rather than mere human antics.
More importantly, the Sun is now changing from its Solar Grand Maximum to its Solar Grand Minimum. The Earth heats up after a Solar Grand Maximum, lagging a bit after the peak. With a Solar Grand Minimum now on its way, a “global cooling” may be on the horizon–a natural oscillation occurring in much longer solar cycles.
Latest science reveals that sharp increases in global warming “precede” sharp increases in CO2–not the other way around. Global warming causes more CO2 to be released form the oceans. Current research also shows that Earth’s oceans are now beginning to cool. It is also now clear that temperatures over the last century correlate far better with cycles in oceans than they do with carbon dioxide; and, the temperature cycles in oceans are caused by cycles of the sun.
Let the AGW (Anthropogenic Global Warming) advocates, as well as the media, continue to ignore all of this, perpetuating fear and advocating spending billions of dollars on non-solutions. Although humans contribute to greenhouse gases, the overall effect is a tiny fraction compared to natural causes. To say humans are the cause of global warming; and to also make predictions that global warming will continue to increase is simply inaccurate. This is not to ignore the silver lining of the global warming scare, as humanity must certainly learn to participate in harmony with nature, with the breath of the Earth and with her land and oceans; and with the cycles of the Sun, Moon, planets, and stars.
Read the rest here | <urn:uuid:55649d15-692c-415a-98fb-d2904aea2886> | 2.9375 | 483 | Personal Blog | Science & Tech. | 38.828645 | 2,112 |
I love science. The joy of discovery in pure research combines with applied science to leave me fantasizing about future technology. Add in the occasional WTF moment and the comedy inherent in poorly prepared presentations, and you have the perfect occupation. Unfortunately, science sometimes attracts people who pull the wings off a cockroach, pin it on its back, and stick electrodes inside it to use it as a mini-electricity generator.
Now, I hate cockroaches as much as anyone, and there is a certain satisfaction in extracting revenge for all those restless nights in rooms that, shall we say, rustled, but... Surely there was a good reason for this?
The basic goal of the research was to see if something like a cockroach could generate enough electricity from stored sugars to power electronic devices. Now, instead of doing what you or I would do—set fire to the cockroach and use the heat to generate electricity—the researcher chose to preserve the life of the insect by employing a redox reaction. The idea being that, with the right configuration, we could get sensors that are both carried and powered by insects, which we could use for all sorts of purposes. This seems like a pretty good reason.
In a standard reaction (like burning something), we are oxidizing one substance and reducing another to release copious amounts of energy. Usually, all the reaction products are in one place. We don't notice that the burning process is, at its most basic, very simple: the transfer of electrons from one molecule to another. Once you realize that, you know that the reaction products can be physically separated, and we can get the electrons to do something useful on the way from one molecule to another.
Sitting inside the cockroach abdomen is a whole lot of sugar waiting to be burned. Outside is a lot of oxygen eager to burn the sugar. The researchers connected the two via electrodes. And, because this highly controlled method of burning requires some help, enzyme catalysts were added at both electrodes.
The result is a tiny amount of power (1 microwatt). But the idea is to get just enough power to drive a few very low-power sensors. Then, combined with a previously developed moth-steering system, we have the perfect spy.
Of course, the fact that the cockroach has to carry around a bottle of enzymes for one electrode is a small disadvantage, but, no doubt, that is something that the researchers are working on. The thing that I find strange about this research is that they also demonstrated that you can get the same reaction and similar power from a dried mushroom. Of course, mushrooms aren't especially mobile. But, considering that the cockroach was pinned down during the experiments and a self-propelled battery was never the intention of the paper, I wonder why they used a cockroach at all?
The only reasonable conclusion is revenge.
Don't get me wrong, I think the idea of insect-powered sensors is a pretty cool idea. It has applications far beyond secret squirrel spy stuff. But I also think that the time to start doing these sorts of experiments is when you are a bit further along the track to a proof-of-principle design.
Journal of the American Chemical Society, 2012, DOI: 10.1021/ja210794c | <urn:uuid:1cbb10d3-b417-4589-88dc-51d408760223> | 3.703125 | 673 | Personal Blog | Science & Tech. | 47.669643 | 2,113 |
While the familiar green-and-black Dog-Day Cicadas are present every July and August in small numbers, the Periodical Cicadas appear, simultaneously, only once in seventeen years in any given area.
Periodical cicadas do not emerge everywhere at the same time.
Twelve broods of 17-year cicadas appear in different areas of the northeastern U.S. in different years, emerging from late May through June.
Their bright red eyes and reddish markings distinguish the Periodical Cicadas from the Dog-Day Cicadas which emerge later in the summer (July through August) and have green markings.
Each brood actually consists of up to three separate species which all emerge together.
Each looks slightly different and the males of each species court their ladies with a different serenade.
If a human takes the time to listen and try to sort out what seems to be cacophony, he or she can easily distinguish these three songs.
Maps of 17-Year Broods and Emergence Years from Display at Cincinnati Zoo
Males of Magicicada septendecim (on left) and Magicicada cassini (on right) Two of the Three Species Which Emerge Together
It just so happens that a “borderline” between two of these broods runs somewhere through eastern Hamilton County and western Clermont County, Ohio.
Thus, Cincinnati residents got their taste (in some cases, literally) of cicadas in 1987 while many Clermont and Brown County residents got their turn in 1991.
Brood X (that’s a Roman numeral “10”) emerged in the central and western parts of Hamilton Co. in 1987, and is due again, in 2004.
Brood XIV emerged in eastern Hamilton Co., Clermont Co., and east of there in 1991, and is due, again, in 2008.
Clermont College is uniquely situated on the border between these two broods and could serve as a host institution to entomologists who may come to Cincinnati to study this “border” area.
Why does this border exist? What keeps the two broods from overlapping?
There were Periodical Cicadas emerging on campus in 1991 and in the 2000 early emergence, and they have been emerging in 2004. All three species of Periodical Cicadas have been heard singing on campus in the 2004 emergence.
Maps of Brood Distribution and Emergence Years in Ohio, Edited from Publication by Ohio State Extension Service
Many Cicadas on a Tree Trunk
In 1987, the Cincinnati Zoo, Cincinnati Museum of Natural History, College of Mount Saint Joseph, and other cooperating institutions generated national and international publicity for the Cincinnati area, even though Brood X is one of the largest broods and also emerged in Washington DC and New York City.
The BBC and Children’s Television Workshop were among the media crews who came to Cincinnati to film.
Leading cicada experts Monty Lloyd (Univ. of Chicago) and Tom Moore (Univ. of Michigan) both came to Cincinnati to study Brood X.
Chris Simon is also a leading cicada expert.
We are fortunate that another cicada expert, Gene Kritsky, resides here in the Cincinnati area and teaches at the College of Mount Saint Joseph.
A Group of Periodical Cicadas on a Virburnum Plant
In late-April and early-May, just before the adult Periodical Cicadas are due to emerge, people may see numerous mud “chimneys” in their yards, especially if there is a tree nearby.
Each of these is caused by a cicada nymph (a young cicada who lives underground) pushing mud up out of its burrow following rainy weather.
Sometimes, if the chimney is quickly broken off, the nymph can be seen retreating down its tunnel.
Cicada Nymph Underground
Cicada Nymph in Its Hole
Mud Cicada Chimneys
When a cicada nymph is ready to molt to an adult (many experts think that it happens when the soil temperature reaches a constant minimum of 64° F or 18° C), it will emerge from its burrow by night, making a visible exit hole, climb a nearby tree or bush, then shed its skin and molt into an adult cicada.
Then, the sights of numerous cicada skins on and under trees and the noisy, black-and-red adult cicadas will become common for about four to six weeks.
In the 2000 early emergence, the first cicadas I collected emerged on 12 May, and in 2004, the first ones were collected on 10 May.
Cicada Molting from Nymph to Adult
Cicada Expanding its Wings
Numerous Cicadas Molting
Hardened Adults, Ready-to-Go, and Shed Skins
Many people wonder if adult cicadas feed.
This cicada is sucking sap from a holly twig.
Cicada Adult Feeding on Holly
Each species of cicada has a characteristic song, and the songs of the three males can easily be distinguished by a human listener.
The song of Magicicada septendecim sounds like “pharaoh.”
The song of M. cassini sounds sort of like someone trying to get a lawnmower started.
The song of M. septendecula sounds like a lawnmower that’s “just chugging along.”
Male cicadas’ songs are produced by a pair of vibrating structures which are located in covered cavities behind their back wings.
The different species sing at different times of day.
Choruses of M. septendecim are most common in the morning,
choruses of M. cassini are most common in mid- to late-afternoon, and
choruses of M. septendecula are most common around midday.
The University of Michigan Museum of Zoology Periodical Cicada Web Site
has samples of the songs of all three species.
Male Cicada with Wing Lifted to Show Tympanum
By looking at the bottom sides of a number of cicadas, one can soon learn to tell the males (with rounded back end) from the females (with pointed back end).
The end of a female cicada’s abdomen is formed into a sword-like ovipositor.
Following mating, the females lay their eggs in slits which they make in small tree twigs and branches.
Male (on right) and Female (on left) Periodical Cicadas (Magicicada septendecim)
Male and Female Cicada Mating
Female Ovipositing (Laying Eggs) in Tree Branch
About a month later in the summer, the eggs will hatch, and the tiny nymphs will fall to the soil and climb into cracks or burrow in using their enlarged front legs.
Cicada nymphs insert their mouthparts into tree roots from which they suck sap (It is thought that tiny, new hatchlings may, at first, feed on grass roots.).
For the next 17 years they will live underground, using their soda-straw-like mouths to suck sap from tree roots.
Imagine eating nothing but watered-down maple syrup your whole life!
No wonder it takes them so long to grow up.
Nymphs remain underground until they are ready to molt to adults.
Egg Slits in a Tree Branch
Eggs in Egg Slits
For these Periodical Cicadas, this takes 17 years — or at least it’s “supposed” to.
Most of the Periodical Cicadas in the northern part of the U.S. are on 17-year cycles, while most of those in the southern parts are on 13-year cycles.
Thus, some Periodical Cicada experts feel that there are three species of 17-year cicadas and three species of 13-year cicadas for a total of six species, while other researchers feel that there is a total of only three species, and that the 13- vs 17-year cycles are genetically-controlled (like brown vs blue eyes in people).
Here in the Cincinnati area, the emergences of Brood X every 17 years are well-documented for at least the last 100 years, and we know that they are due, again, in 2004.
However, in 1983, four years before the big 1987 emergence, there was a small emergence, and
in the year 2000, as predicted by Dr. Gene Kritsky, a considerable “small” emergence occured in the greater Cincinnati area, four years before the upcoming 2004 emergence.
Children who have never seen these cicadas before and may not see them again, soon, have a natural curiosity about them.
An observant person will soon realize that not all cicadas have red eyes.
In 1987 in Cincinnati, cicadas were found with white, pale blue, orange, butterscotch, and chocolate brown eyes.
The wings of cicadas are reported to filter out ultraviolet light, and people who have placed a cicada wing on their skin prior to exposure to the sun have noticed that the spot under the wing does not tan.
Eye Colors: Strawberry, Vanilla, Chocolate, and Butterscotch
Periodical Cicadas pose no threat to most humans.
They can not bite or sting and if they land on you, it is purely accidental — you might as well be a rock from their point of view.
They do not carry any diseases communicable to humans.
Because of their soda-straw-like mouths, they cannot eat the leaves of your plants.
Contrary to “urban legend,” cicadas cannot lay eggs in a child’s hand, nor will they eat the plants in your garden!
However, some allergic people may react, adversely, to consumed cicadas. In 2004, a man who knew he was allergic to “shellfish” made the news when he had to be rushed to the hospital after eating, reportedly, 30 cicadas at once.
Remember that, just as humans, birds, fish, frogs, and snakes are all members of phylum Chordata, so also cicadas, shrimp, millipedes, centipedes, and spiders are all members of phylum Arthropoda.
However, cicadas are good to eat.
These are good mole food.
Thus, the mole population rises in an emergence year as they feast on underground nymphs.
Songbirds and other wildlife will consume large numbers of adult cicadas as will cats and dogs.
In general, it will not hurt cats and dogs to eat cicadas.
In 1987 however, several veterinarians in Cincinnati had to treat cases in which the animal had consumed so many cicadas, simultaneously, that the skins (which are non-digestible roughage) had blocked a portion of the animal’s digestive track.
Many other animals also prey upon adult cicadas, and the reproductive strategy of the cicadas is to emerge in such large numbers that the predators are satiated.
In years when Periodical Cicadas emerge, many more young songbirds survive because the parents can find food more easily.
(Cicada-killer wasps, which emerge later in the summer along with the Dog-Day Cicadas, capture and paralyze those cicadas (but they do not come out early enough to make use of the Periodical Cicadas). They then place the cicadas into burrows as food for their developing young.)
Dead Cicadas are Food for Ants
Cicadas are Food for Cats and Dogs
In many cultures around the world, people eat cicadas, too.
The ancient Greeks considered cicadas a delicacy.
Many tribes of Native Americans ate cicadas both before and after the colonists arrived.
Cicadas are eaten in Australia, Thailand, Papua New Guinea, and Japan.
In the society section of the June 2, 1902 Cincinnati Enquirer, an account was given of a party where cicada-rhubarb pie was served.
In 1987 in Cincinnati a number of people took the opportunity to try batter-dipped, deep-fried cicadas or cicada stir fry and a certain radio station enraged a certain pizza company.
Ironically, in 2004, that pizza company resurrected their own version of the song!
In 1990 in Chicago, cicada-eating was so popular that it made the pages of Time Magazine.
Just make sure the neighbors haven’t been using insecticide.
A Web search for “cicada” and “recipe” will turn up quite a number of pertinent Web pages.
Battered, Deep-Fried Cicadas are Yummy (Just Ask George and Gene)
Newly-emerged (teneral) adult cicadas may be collected around midnight, as they are emerging from the ground and molting.
These soft, white cicadas should be blanched (like vegetables from your garden that you are preparing to put in the freezer), or they will bruise and discolor.
To blanch teneral cicadas, boil about one minute then drain.
At this point, they may be frozen for storage, if desired.
More recipes from the 26 May 2004 Clermont College Cicada Cook-Off
water chestnuts and/or other vegetables of your choice
bean sprouts and snow peas
blanched, teneral cicadas
In a wok or other suitable pan, heat a couple tablespoons of vegetable oil.
Add ingredients in the order listed above when those in the most recent addition are partially cooked.
Serve over whole-grain (“brown”) rice and add soy sauce to taste.
Dip teneral cicadas in batter, then deep-fry until golden brown. Drain, then serve with cocktail sauce.
1902 Cicada-Rhubarb Pie:
Make your favorite recipe for rhubarb pie, including some blanched, teneral cicadas.
The Ancient Greeks Ate Another Species of Cicadas
Although large trees can tolerate and may even benefit from the “damage” caused by egg-laying females, young trees can be severely damaged and should be protected.
Because females make slits in small diameter branches, a sapling whose trunk and main branches are still small is at risk of having significant injury.
In years when periodical cicadas emerge, young trees can be effectively protected so that the females cannot lay eggs on them.
This may be done by covering the trees with loose “bags” of cheesecloth or screening, tied securely at the base.
Larger, mature trees often respond to this “pruning” of the ends of the branches by producing more branches.
Young Tree with Net Cover
Cicada “Pruning” in an Older Crabapple Tree (Note Dead, Broken End of Branch)
A certain species of fungus attacks Periodical Cicadas, causing the back ends of their bodies to fall off and eventually killing them.
This fungus has a 17-year life cycle, which is timed to coincide with the emergence of the adult cicadas.
Gene Kritsky and others have hypothesized that perhaps some Periodical Cicadas have evolved a 13-year life cycle is to avoid that fungus.
Fungus-Filled Cicada Missing the End of Its Abdomen
Other kinds of cicadas are a part of the folklore of many cultures.
Artists and poets of many cultures have been inspired by cicada and their songs.
Goethe, Browning, Tennyson, and Anatole France are just a few of the poets whose works include reference to cicadas.
Gene Kritsky has reported that in China, shed skins or actual nymphs from a different species of cicada nymphs (all of which which are silent) are collected and ground up.
A tea made from these skins is given to noisy, crying babies (like noisy, adult cicadas), in hopes of quieting them.
People think the baby will then be quiet like the cicada nymph rather than noisy like the adult cicada.
Similarly, the shed skins are used to treat “ringing in the ears.”
The cicada nymph burrowing out of the ground has been a symbol of rebirth or reincarnation in a number of societies.
For example, Native Americans of the Oraibi tribe believed that these cicadas had the power to renew life and made a medicine from them which was used to treat battle wounds.
In Mayan, Aztec, and Chinese cultures, carved, Jade cicadas were placed on the tongue of a corpse prior to burial so that the deceased would some day re-animate and/or go on to better things like a cicada nymph coming out of the ground and shedding its nymphal skin.
The Japanese, famous for their beautiful and intricate kites, frequently make these in the likeness of cicadas.
In China, male cicadas are kept in cages in people’s homes so that the homeowners can enjoy the cicadas’ songs.
In Navajo mythology, the cicada-god fought the birds and rescued Earth for humans.
The people of Provence, France consider cicadas to be good luck.
Good-luck charms in the shape of cicadas are popular items there.
A Zuni Legend: “Once upon a time, a cicada singing from a pine bough excited the admiration of a coyote, who asked
that he might be taught the song. He was not an apt pupil, but in the end, and after a fashion, he learned
the tune. On the way home, the proud coyote stumbled in a gopher’s hole. Between the shock
of the fall and the dust in his eyes and nose, every detail of the tune was forgotten. Twice an accident
occurred, and twice the coyote returned to his teacher perched upon the pine bough. The second
time, the distrustful cicada had resolved to take no more risks, but rather to teach the coyote a lesson
of another kind. Strongly gripping the bark, he swelled and strained until his back split open and he
was able to slip out of his old skin, which still retained its shape and position. Choosing a suitable
quartz pebble, he popped this into the skin and flew to a neighboring tree. There on the pine branch,
he left his empty skin which gave back no answer to the requests of the returning coyote. Soon the
patience of the latter was exhausted, and with a spring he seized the counterfeit cicada and splintered
his teeth on the stone inside. The teeth in the middle of his jaw were crushed so far down into his
gums that one could barely see them, and all of his descendants to this day have inherited his broken
teeth. So also, to this day, when cicadas venture out on a sunny morning to sing, it is frequently their
custom to protect themselves by leaving their counterparts on the trees.”
Coyote and Cicada
When some people say “locust,” they mean a cicada.
However, when entomologists say “locust,” they mean a grasshopper.
An example of this is the locust plagues mentioned in the Bible.
When a brood of cicadas emerged a few years after the first white colonists arrived in the New England area, they thought these were the Biblical locusts, and the incorrect name stuck.
When botanists say “locust,” they mean a kind of tree. | <urn:uuid:e6423897-1ce8-442e-ade5-54350d1fc74e> | 3.53125 | 4,206 | Knowledge Article | Science & Tech. | 48.413739 | 2,114 |
Yes, it's the secondary effects that require energy.
A ship launched vertically must not only get the kinetic energy of final velocity, it must also balance against the pull of gravity (i.e. energy required to hover) during vertical ascent. It must also overcome air resistance.
An aircraft launch, ie. taking off horizontally, means that forward motion, requiring less initial energy, can create the lift to balance gravity. However, it runs longer, so basically what horizontal lift does is expend about the same amount of energy, but spread over a longer time with weaker engines; possibly more because you are fighting air resistance for a longer time while going horizontally. | <urn:uuid:cb8739e0-69bc-470f-8a3d-17c7e5e399da> | 2.796875 | 133 | Comment Section | Science & Tech. | 32.697821 | 2,115 |
Global ocean levels have risen by 4 to 10 inches over the past 100 years. How much more will they rise in 10 years? What about in 50?
This kind of question is critical for planning future coastal development, but taking the measurements necessary to make predictions can be difficult and downright risky for human surveyors, who could be smashed by falling chunks of ice the size of the Empire State Building.
So send in a bot, says David Holland, an oceanographer at New York University, who teamed up with the National Research Council of Canada (NRC) to deploy a five-foot-long autonomous submarine beneath an iceberg off the coast of Greenland. Called the Slocum underwater glider, the sub propels itself through water with a single-stroke piston, thereby conserving most of its energy for data collection. Sensors under the port-side wing measure conductivity (to find the salinity of the water), temperature, and depth, sending the data to processors within the sub.
Icebergs are difficult to navigate, even for a sophisticated machine like this. In the pitch-black shadow under the iceberg, the Slocum glider has no access to satellite GPS and no visual markers to verify that it is following its intended path. To help the glider get and keep its bearings, the NRC plans to test an acoustic beacon system whose components would be placed underwater at strategic points around an iceberg, allowing the glider to triangulate by sound.
By collecting data on how much and how quickly Greenland’s ice is melting, Holland hopes to create a computer model that will simulate and forecast glacial melt—and the future rise in sea levels—around the world. | <urn:uuid:a936095d-022f-4127-8334-a3c903fdb6f3> | 3.9375 | 345 | News Article | Science & Tech. | 39.404584 | 2,116 |
In digging for news on the nor’easter that whacked New England (and my house in southeastern Massachusetts), I happened upon several compelling images.
Marshall Shepherd, current president of the American Meteorological Society and director of the atmospheric science program at the University of Georgia, tweeted out this annotated version of a Terra MODIS satellite image of the storm aftermath:
It seems that the monumental snowfall highlighted some land features of New England, including its longest river, one of the largest manmade reservoirs in the United States (Quabbin), and the scar of a vicious tornado.
EarthSky published a map of snowfall totals compiled by the National Weather Service Hydrometeorological Prediction Center. About 35 to 40 million Americans live within that snowy bullseye.
Finally, our colleague Jeff Schmaltz on the LANCE/MODIS Rapid Response team noticed that while the skies cleared over New England and the Canadian Maritimes on February 10, cloud streets lined up offshore.
Cloud streets form when cold air moves over warmer waters, while a warmer air layer (or temperature inversion) rests over the top of both. Read more here from my fellow Earth Observatory writer Adam Voiland.
By the way, I am not buying into this idea of naming winter storms. I certainly won’t let it spoil my fondness for Nemo, both the movie and book characters. How do you feel about this idea of naming winter storms? | <urn:uuid:7916aed4-3e3e-452d-91d0-6b9722a1ac4e> | 2.5625 | 299 | Personal Blog | Science & Tech. | 34.143034 | 2,117 |
West Greenland Current
The West Greenland Current is a weak cold water current that flows to the north along the west coast of Greenland. The current results from the movement of water flowing around the southernmost point of Greenland caused by the East Greenland Current.
According to Lloyd et al., 2007, the WGC is a WARM current connected to a broader scale North Atlantic climate via the combined influences of Atlantic water from the Irminger Current (IC) and polar water from the East Greenland Current.
Paleoclimatology records derived from foraminifera abundance show that periodic influxes of warm subsurface temperatures and near-bottom temperatures occurred throughout the Late Holocene epoch, particularly during the Holocene climatic optimum. The increased flow from the nearby East Greenland Current was associated with increased glacial iceberg calving from the large Jakobshavn Isbrae glacial outlet within the western Greenland Ice Sheet, causing rapid melting and destabilization events. Following the Neoglaciation, the Jakobshavn outlet formed a floating ice tongue around 2000 years before present.
See also
- Labrador Current
- Baffin Island Current
- Gulf Stream
- Jakobshavn Isbrae
- Ocean current
- Oceanic gyres
- Physical oceanography
- Source: Llyod, J., Kuijpers, A., Long, A., Moros, M., and Park, L. 2007. Foraminiferal reconstruction of mid- to late Holocene ocean circulation and climate variability in Disko, Bugt, West Greenland. The Holocene: 17: 1079-1091.
- Andresen, Camilla S.; David J. McCarthy, Christian Valdemar Dylmer, Marit Solveig Seidenkrantz, Antoon Kuijpers and Jerry M. Lloyd (September 27, 2010). "Interaction between subsurface ocean waters and calving of the Jakobshavn Isbræ during the late Holocene". The Holocene 21 (2): 221–224. doi:10.1177/0959683610378877. Retrieved 22 March 2011.
|This article about a specific ocean current is a stub. You can help Wikipedia by expanding it.|
|This Greenland-related article is a stub. You can help Wikipedia by expanding it.| | <urn:uuid:b31ce287-84d1-4290-b455-5f7fda724abd> | 3.609375 | 486 | Knowledge Article | Science & Tech. | 44.055782 | 2,118 |
[erlang-questions] Newbie question about line endings
Thu Dec 22 14:30:59 CET 2011
On Wed, Dec 21, 2011 at 8:21 PM, August Schwartzwald <
> I started to learn Erlang about a month ago. I really like it and think
> that with some more practice it will become a both unique and powerful tool
> in my growing box of programming languages. However, there is one thing
> about it that I find extremely annoying: The line endings.
> I currently know 5 programing languages, they have either 0 (python) or 1
> way to end lines (usually the ';' character). Erlang totally stands out
> here and requires that lines are ended in one of 4 different ways.
> Did some googling without finding any good reason to why the language
> works in this way. Can anyone here explain this?
There is no such ting as a "Line" in Erlang. Everything is a "form" so
there are no
line ending only form endings. A form is ended by a top-level "dot
Dot is a period "." white space is a blank,tab,newline or comment.
Comments start with "%" and are terminated by a newline
Top level means dot-whitespace is not contained inside a string, a quoted
atom or a comment.
The dot-whitespace convention came from Prolog, this is because Erlang was
first implemented in Prolog.
I don't really know why this convention was adopted in Prolog - but it might
have been done to simplify error handling. If you get a parse error in a
the parser wants to recover in some way. In Erlang/Prolog the strategy for
error recovery is extremely simple, if you get a parse error in a form the
parser just reports the error and goes to the next form - what constitutes
a form can be seen easily by only
looking at the stream of tokens generated by the tokeniser. This make
from parse errors very simple.
Dot-whitespace can be viewed as a synchronizing token for the purposes of
recovery during parsing of incorrect forms.
The easiest was to think of a form, is that it's like a sentence in English.
In your mail which posed this question, you ended most sentences with
dot whitespace (the exception was ? as a terminator), so Erlang forms are
like English sentences.
Just like in English semicolons are "long range" operators and separate
whereas commas separate short range constructs.
> erlang-questions mailing list
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Well, did you read some books about progamming with C++ for Windows?
Did you try some simple sample applications like "Hello Worlds"?
Some others a little more complicated?
Note, that you cannot from the level "zero" jump to a level for programming serial port communications...
You really, really cannot pick this up as you go along without having a very good grounding in the basics of the c++ language, which is obvious you do not have. You need to start with the very basics and progress one step at a time. You are trying to undertake the triple jump without knowing how to run.
This says that ptr is a pointer to memory containing unsigned characters and that the characters pointed to cannot be changed. An area of memory containing unsigned characters is a character array (or an array of chars). So to use StuffData the first parameter has to be a pointer to an array of chars. So before you call the function StuffData, your program has to put into a char array the characters for StuffData. You cannot get away from not using a character array! This can be either a fixed size array (as in my previous example) or it can be a dynamically allocated memory (use new). However the character array is created, once it has been you need to populate it with the characters for StuffData.
So from your example, you want to use 11 characters. So you need a character array that contains these characters set up before you call StuffData.
The destination characters returned by StuffData in dst are NOT a c-style string and are NOT guaranteed to be NULL terminated. So using printf (or cout) to try to display the contents of dst is a non-starter. Have you actually looked at what StuffData does? It takes an array of char and a length and returns a codified char array where the first char is the number of bytes (including itself) followed by the chars. If the length of the bytes exceeds 255 then a new chuck is started again with the first byte as the length byte. So "qwerty" gets codified as 0x07 'q' 'w' 'e' 'r' 't' 'y'. 0x00 is treated specially and just gets translated as a new chuck of length 1. So after using StuffData, you pass dst to whatever function you use to actually send the data.
All advice is offered in good faith only. You are ultimately responsible for effects of your programs and the integrity of the machines they run on.
The destination characters returned by StuffData in dst are NOT a c-style string and are NOT guaranteed to be NULL terminated. So using printf (or cout) to try to display the contents of dst is a non-starter.
I'd say neither the initial buffer nor the destination one is "a c-style string". Both are just byte sequences with some predefined length.
And there is nothing wrong to use printf (or cout) to output their contents. Just use some proper format specification (like %X, "%08X", "%d" or similar) and do output in a loop for each element in the buffer! | <urn:uuid:5231abde-62e3-4b69-813e-44f46b47e859> | 2.71875 | 645 | Comment Section | Software Dev. | 62.143739 | 2,120 |
Asynchronous evolution of mammalian myosin proteins. The matrix illustrates the normalized distances between corresponding sequences. Asynchronous evolution is observed if the pattern of the deviation from the mean is different. For example, the pattern from rat to the other mammalian species is very similar, illustrating their synchronous evolution in general. However, there are differences in the patterns of some class-I myosins between rat and mouse and opossum, indicating their asynchronous evolution. In contrast, the sequence comparison patterns of cow and the other mammals are very different, indicating the asynchronous evolution of all cow myosin genes. The abbreviations for the organisms are: Rn, Rattus norvegicus; Mm, Mus musculus; Pat, Pan troglodytes; Hs, Homo sapiens; Mam, Macaca mulatto; Caf, Canis familiaris; Bt, Bos Taurus; Md, Monodelphis domestica.
Odronitz and Kollmar Genome Biology 2007 8:R196 doi:10.1186/gb-2007-8-9-r196 | <urn:uuid:05a54f37-4c7b-40e1-883f-0cef47a6c3c6> | 2.59375 | 225 | Academic Writing | Science & Tech. | 27.36382 | 2,121 |
NASA scientists captured some footage of Plasma Indirection, a plasma shift on the surface of the Sun that looks like huge tornadoes churning. Pretty amazing stuff.
As if it could not make up its mind . . . darker, cooler plasma slid and shifted back and forth above the Sun’s surface seen here for 30 hours (Feb. 7-8, 2012) in extreme ultraviolet light. An active region rotating into view provides a bright backdrop to the gyrating streams of plasma. The particles are being pulled this way and that by competing magnetic forces. They are tracking along strands of magnetic field lines. This kind of detailed solar observation with high-resolution frames and a four-minute cadence was not possible until SDO, which launched two years ago on Feb. 11, 2010. So it’s our 2nd Anniversary! | <urn:uuid:859b72c9-5c36-4f90-b40b-9e16cde07631> | 2.75 | 171 | Personal Blog | Science & Tech. | 62.814615 | 2,122 |
There's a popular theory that bird and mammal evolution kicked into high gear after the dinosaurs went extinct. But now it turns out lice were already diversifying long before the dinosaurs died out.
This is significant because lice would only start to diversify when their various hosts - in other words, birds and mammals - were themselves starting to diversify into lots of different species. We know that, in the last hundred million years, birds and mammals have spread into almost every available ecological niche, and most researchers assumed that this happened shortly after the dinosaurs went extinct 65 million years ago, thus opening up all this prime ecological real estate.
But now, new research by University of Illinois ornithologist Kevin Johnson suggests that lice started diversifying before the extinction event at the end of the Cretaceous. This, as he explains, means big things for bird and mammal evolution:
This study lends support to the idea that major groups of birds and mammals were around before the dinosaurs went extinct. If the lice were around, we know their hosts were probably around. Ducks do different things from owls, which do different things from parrots, for example, and it was thought that after the dinosaurs went extinct that's when these birds or mammals diversified into these different niches. But based on the evidence from lice, the radiation of birds and mammals was already under way before the dinosaurs went extinct.
Lice really do undergo some dramatic evolutionary transformations to better fit with their preferred host. Gopher lice, for instance, have special grooves on the tops of their heads that allow them to hold onto a single hair, while wing lice have unusually long bodies that allow them to squeeze into the barbs of the bird's feather. These adaptations essentially lock the lice into one particular host species, meaning they would only happen in the presence of mass diversification.
Beyond the basic elegance of the idea that birds and mammals started diversifying after the dinosaur extinction, there was also the fact that the oldest fossils that resemble modern species all date back to less than 65 million years ago. The newly found lice fossils are only indirect evidence of earlier diversification, to be sure, but it's hard to reconcile these lice fossils with the current paradigm. If radiation did begin before the dinosaurs died out, it also means we have to come up with some new explanation for why birds and mammals started diversifying in such great numbers.
Johnson also tackles another crucial question...did dinosaurs themselves have lice?
"Our analysis suggests that both bird and mammal lice began to diversify before the mass extinction of dinosaurs. And given how widespread lice are on birds, in particular, and also to some extent on mammals, they probably existed on a wide variety of hosts in the past, possibly including dinosaurs. So maybe birds just inherited their lice from dinosaurs." | <urn:uuid:a3982b11-efbd-46d0-8e6a-cead5716f35e> | 3.75 | 579 | News Article | Science & Tech. | 36.617176 | 2,123 |
cpphs is a liberalised re-implementation of cpp, the C pre-processor, in Haskell.
Why re-implement cpp? Rightly or wrongly, the C pre-processor is widely used in Haskell source code. It enables conditional compilation for different compilers, different versions of the same compiler, and different OS platforms.
It is also occasionally used for its macro language, which can enable certain forms of platform-specific detail-filling, such as the tedious boilerplate generation of instance definitions and FFI declarations. However, there are two problems with cpp, aside from the obvious aesthetic ones:
* For some Haskell systems, notably Hugs on Windows, a true cpp is not available by default. * Even for the other Haskell systems, the common cpp provided by the gcc 3.x series is changing subtly in ways that are incompatible with Haskell's syntax. There have always been problems with, for instance, string gaps, and prime characters in identifiers. These problems are only going to get worse.
So, it seemed right to provide an alternative to cpp, both more compatible with Haskell, and itself written in Haskell so that it can be distributed with compilers.
This version of the C pre-processor is pretty-much feature-complete, and compatible with the -traditional style. It has two main modes:
* conditional compilation only (--nomacro),
* and full macro-expansion (default).
In --nomacro mode, cpphs performs only conditional compilation actions, namely #include's, #if's, and #ifdef's are processed according to text-replacement definitions (both command-line and internal), but no parameterised macro expansion is performed. In full compatibility mode (the default), textual replacements and macro expansions are also processed in the remaining body of non-cpp text.
#ifdef simple conditional compilation
#if the full boolean language of defined(), &&, ||, ==, etc.
#elif chained conditionals
#define in-line definitions (text replacements and macros)
#undef in-line revocation of definitions
#include file inclusion
#line line number directives
line continuations within all # directives
/**/ token catenation within a macro definition
## ANSI-style token catenation
# ANSI-style token stringisation
__FILE__ special text replacement for DIY error messages
__LINE__ special text replacement for DIY error messages
__DATE__ special text replacement
__TIME__ special text replacement
Macro expansion is recursive. Redefinition of a macro name does not generate a warning. Macros can be defined on the command-line with -D just like textual replacements. Macro names are permitted to be Haskell identifiers e.g. with the prime ' and backtick ` characters, which is slightly looser than in C, but they still may not include operator symbols.
Numbering of lines in the output is preserved so that any later processor can give meaningful error messages. When a file is #include'd, cpphs inserts #line directives for the same reason. Numbering should be correct even in the presence of line continuations. If you don't want #line directives in the final output, use the --noline option.
Any syntax errors in cpp directives gives a message to stderr and halts the program. Failure to find a #include'd file produces a warning to stderr, but processing continues.
Differences from cpp:
In general, cpphs is based on the -traditional behaviour, not ANSI C, and has the following main differences from the standard cpp.
· The # that introduces any cpp directive must be in the first column of a line (whereas ANSI permits whitespace before the #).
· Generates the #line n "filename" syntax, not the # n "filename" variant.
· C comments are only removed from within cpp directives. They are not stripped from other text. Consider for instance that in Haskell, all of the following are valid operator symbols: /* */ */* However, you can turn on C-comment removal with the --strip option.
· Macros are never expanded within Haskell comments, strings, or character constants, unless you give the --text option to disable lexing the input as Haskell.
· Macros are always expanded recursively, unlike ANSI, which detects and prevents self-recursion. For instance, #define foo x:foo expands foo once only to x:foo in ANSI, but in cpphs it becomes an infinite list x:x:x:x:..., i.e. cpphs does not terminate.
Macro definition language
· Accepts /**/ for token-pasting in a macro definition. However, /* */ (with any text between the open/close comment) inserts whitespace.
· The ANSI ## token-pasting operator is available with the --hashes flag. This is to avoid misinterpreting any valid Haskell operator of the same name.
· Replaces a macro formal parameter with the actual, even inside a string (double or single quoted). This is -traditional behaviour, not supported in ANSI.
· Recognises the # stringisation operator in a macro definition only if you use the --hashes option. (It is an ANSI addition, only needed because quoted stringisation (above) is prohibited by ANSI.)
· Preserves whitespace within a textual replacement definition exactly (modulo newlines), but leading and trailing space is eliminated.
· Preserves whitespace within a macro definition (and trailing it) exactly (modulo newlines), but leading space is eliminated.
· Preserves whitespace within macro call arguments exactly (including newlines), but leading and trailing space is eliminated.
· With the --layout option, line continuations in a textual replacement or macro definition are preserved as line-breaks in the macro call. (Useful for layout-sensitive code in Haskell.)
What's New in This Release:
· This release fixes some more obscure corner cases involving parameterised macro expansion within conditionals.
· Internal refactoring affecting parts of the library API has been performed. | <urn:uuid:529d2ec8-9f62-4d26-930e-027e326b701f> | 2.828125 | 1,294 | Documentation | Software Dev. | 31.875616 | 2,124 |
Changing Ideas About The Origin Of Life
By Enrico Uva | August 6th 2012 02:00 AM
For life to begin, a combination of inorganic and organic substances need to evolve biochemistry. When 20th century scientists accepted and elaborated on J.B.S Haldane’s primordial soup hypothesis, their guesses and suggestive experiments centered mostly around the mature field of organic chemistry. But biochemistry as a science was still in its infancy. Their hunches were like those of aliens trying to account for our transition from hunter gatherer-groups to civilization without understanding the roles of agriculture, division of labor and writing.
(1) Primordial Catalysts Were Probably Not Proteins
In the 1960′s, RNA‘s role as a catalyst and replicator was greatly underestimated. Unaware of retroviruses, or at least of their reproductive mechanism, biochemists believed that information only flowed from DNA to RNA, and they perceived proteins to be the only biological catalysts. After the discovery of ribozymes revealed that tertiary RNA molecules could speed up their own production, it was hypothesized that these were life’s first catalysts because they could have evolved from single-stranded RNA molecules, which are structurally simpler than both DNA and proteins.
But the current popular notion that RNA was essentially the sole primeval replicator and catalyst has also come under attack. As an alternative, the first catalysts may have also included inorganic ions. Hydrothermal vents are rich in iron (II) sulfide (FeS) and nickel (II) sulfide, both of which can speed up biochemical reactions. In existing hydrothermal bacteria and archaebacteria, these compounds are part of protein complexes, but the ions are the reactive catalytic centers for a remarkable exergonic reaction. Hydrogen gas from the vents combines with dissolved carbon dioxide in the sea (and an acetyl-less CoA ) to produce water and acetylCoA (a key molecule involved in releasing energy from sugars; in fatty acid synthesis etc). The overall reaction releases 59 kJ of free energy for every 2 moles of fixed CO2, enough to drive the synthesis of ATP.
Another argument against RNA exclusivity from Lane, Allen and Martin is that each time RNA makes a copy of itself in a “primordial soup” its concentration drops so the rate of reaction can only be maintained if nucleotides are continuously replenished. This brings us to the issue of energy.
(2) First Energy Source Likely Involved Proton Gradients
In the same way that a room only remains tidy and dustless with continuous effort, life forms are capable of maintaining order only in the presence of a continuous energy supply. Even before life arises, the required conversions of small molecules to larger ones are endothermic. Whereas the original hypotheses were careful enough to exclude oxygen from the original mix because an oxidizing atmosphere would break up newly made molecules, the irony is that the proposed energy sources, ultraviolet and lightning, would also destroy newly synthesized molecules. The excessive heat and low pH‘s from deep, volcanic hydrothermal vents do not lead to a viable energy alternative.
But Lane, Miller and Allen point out that there is another hydrothermal vent which gets its heat from the mid Atlantic’s tectonic boundaries, known as the Lost City, where olivine mineral (a combination of magnesium and iron silicates) turns to surpentine (hydroxylated iron and magnesium silicates).
This is the source of hydrogen gas used by the previously mentioned bacteria to “fix” carbon dioxide into acetyl, a part of a vital metabolite. The hydroxides formed are not inconsequential because, with the help of simple membranes, they provide a natural pH-gradient, essentially a voltage, one that was more pronounced in ancient seas due to CO2 concentrations that were 1000 times higher than their modern counterpart. Remarkably that gradient is comparable to the one created by the biochemical processes in today’s cells.
Forty years ago, this idea that chemiosmosis was the energy-provider for earth life’s first cells could not be put forth because no one understood how the universal reaction-facilitator, ATP(adenosine triphosphate), was made from ADP(adenosine diphosphate). But given that proton gradients power ATP production in all kingdoms of life: in respiration, photosynthesis and in rotating motors of bacterial flagella, the hypothesis is now plausible. The enzyme ATP synthase is a molecular machine whose “blades” are rotated by H+ that are put in motion by coulombic repulsion. The enzyme-portion attracts and combines ADP with a phosphate group and the spinning nanomachine releases the ATP.
DiMauro has spent 10 years working on the chemistry of 1-carbon amide formamide (H2NCOH), subjecting it to a variety of conditions and mineral catalysts. He has produced all four nucleic acids and a variety of carboxylic acids. What works best is when he uses a pH of 9 to 10 and temperatures in the 80–160 ◦C range, conditions that are found in non-volcanic hydrothermal vents.
(3) Knowledge of New Bacterial Kingdoms Downplays Role of Fermentation In First Cells
The authors of How did LUCA make a living? Chemiosmosis in the origin of life. BioEssays. January 2010 refute the popular notion that fermentation was used by the first cells to release chemical energy from food molecules. Aside from the idea that fermentation seems to be a derived chemical process, when comparing bacteria to archaea, there are also major differences in the gene sequences of fermentation enzymes. On the surface they seem like similar processes, but in reality the release of energy in oxygen’s absence evolved separately and independently. It’s essentially convergent evolution, the way Old World Euphorbia and New World cacti have similar adaptations but are not related.
Clostridia-type fermentations (Clostridia are sulfite reducing bacteria that include tetanus-producing bacteria), which represent ancient lineages, actually involve chemiosmosis, which of course exploits ion gradients across the cytoplasmic membrane and rotor–stator type ATPases (enzymes that cleave ATP to place a good leaving group on otherwise nonreactive molecules). The same is true of fermentation in most free-living anaerobic bacteria.
Writing in 1969, Calvin wrote:
As long as we are limited to biology as it is on the earth, it is going to be difficult for us to be sure that such a system occurred in the way described in this book. We shall have to find other places in the universe, preferably nearby, in which this process is going on and has not gone all the way, so that we can observe it at some other stage of its development. this is why I am interested in lunar and planetary exploration.
In four decades no such places have been found yet, but at least something esoteric has been discovered at the bottom of our own oceans. It’s far from direct evidence, which of course eludes everyone because the molecular precursors to primordial life left no traces. But along with more detailed knowledge of biochemistry, the Lost City has inspired hypotheses that bring us closer to a non-fictitious narrative of our chemical history.
How did LUCA make a living? Chemiosmosis in the origin of life
LAM BioEssays | pdf file
- William F. Martin Edited by Miguel Teixeira and Ricardo O. Louro Hydrogen, metals, bifurcating electrons, and proton gradients: The early evolution of biological energy conservation Febs Letters Volume 586, Issue 5, 9 March 2012, Pages 485–493
- Nick Lane, John F. Allen, William Martin. How did LUCA make a living? Chemiosmosis in the origin of life. BioEssays. January 2010 (whole article can be read free of charge)
- Michael J. Russell, William Martin. The Rocky Roots of the Acetyl-coA Pathway TRENDS in Biochemical Sciences Vol.29 No.7 July 2004 (whole article can again be read free of charge)
- Calvin, M. (1969). Chemical evolution: Molecular evolution towards the origin of living systems on the earth and elsewhere. Oxford: Clarendon Press. QH325 .C26
Enrico Uva (2012). Changing Ideas About The Origin Of Life Science 2.0 | Chemical Education
Tracing Knowledge Notification | Ειδοποίηση Στα ίχνη της Γνώσης
of the original post, out of respect to the source and readers.
Please follow the link for references and more informations.
της πρωτότυπης δημοσίευσης με σεβασμό στην πηγή και στους αναγνώστες.
Παρακαλώ επισκεφθείτε τον σύνδεσμο για περισσότερες πληροφορίες. | <urn:uuid:cba9b995-2e8f-4763-b024-81aace16e109> | 3.015625 | 2,026 | Personal Blog | Science & Tech. | 34.639729 | 2,125 |
If the Reynolds number is small enough (Re<<1), then two fluids can flow in parallel in direct contact, exchanging momentum and species only by diffusion. If the interface is
stable, then this system can be used as a filter. In this problem, the flow fields in both fluids are found.
2008 Carlos Martinez and Matthew John M. Krane
Difficulty level: Junior; Solution time: 1 hour; Reference: J. P. Brody,et al., "Biotechnology at Low Reynolds Numbers," Biophysical Journal., v.719, pp. 3430-3441, | <urn:uuid:fbd18c75-6e77-4a88-926e-69a8f121a6c1> | 2.921875 | 122 | Academic Writing | Science & Tech. | 73.423286 | 2,126 |
Question: If the work required to stretch a spring 1 ft beyond its natural length is 9 ft-lb, how much work W is needed to stretch it 10 in. beyond its natural length?
So my teacher today gave us some physics equations and said to do this homework. Im a little stuck on this, usually they give us the force required to stretch a spring, not the work. Here is what i tried:
Then I did F=KX (hooke's law) to solve for the k constant of the spring
9 = K * 1 ft
K = 9
So I now know that F = 9X (equation for force of a spring when you know the k constant of that spring)
And then i said the:
INTEGRAL of: 9x from 0-10/12 = Total work needed to stretch the spring 10inches.
I get 7.25, but this answer is wrong. | <urn:uuid:04a804c3-a025-48b1-ad1e-93aa63f2ec07> | 2.71875 | 192 | Q&A Forum | Science & Tech. | 93.915541 | 2,127 |
To find out your matplotlib version number, import it and print the __version__ attribute:
>>> import matplotlib >>> matplotlib.__version__ '0.98.0'
You can find what directory matplotlib is installed in by importing it and printing the __file__ attribute:
>>> import matplotlib >>> matplotlib.__file__ '/home/jdhunter/dev/lib64/python2.5/site-packages/matplotlib/__init__.pyc'
Each user has a .matplotlib/ directory which may contain a matplotlibrc file and various caches to improve matplotlib’s performance. To locate your .matplotlib/ directory, use matplotlib.get_configdir():
>>> import matplotlib as mpl >>> mpl.get_configdir() '/home/darren/.matplotlib'
On unix-like systems, this directory is generally located in your HOME directory. On windows, it is in your documents and settings directory by default:
>>> import matplotlib >>> mpl.get_configdir() 'C:\\Documents and Settings\\jdhunter\\.matplotlib'
There are a number of good resources for getting help with matplotlib. There is a good chance your question has already been asked:
If you are unable to find an answer to your question through search, please provide the following information in your e-mail to the mailing list:
your operating system; (Linux/UNIX users: post the output of uname -a)
matplotlib version:python -c `import matplotlib; print matplotlib.__version__`
where you obtained matplotlib (e.g. your Linux distribution’s packages or the matplotlib Sourceforge site, or the enthought python distribution EPD).
any customizations to your matplotlibrc file (see Customizing matplotlib).
if the problem is reproducible, please try to provide a minimal, standalone Python script that demonstrates the problem. This is the critical step. If you can’t post a piece of code that we can run and reproduce your error, the chances of getting help are significantly diminished. Very often, the mere act of trying to minimize your code to the smallest bit that produces the error will help you find a bug in your code that is causing the problem.
you can get very helpful debugging output from matlotlib by running your script with a verbose-helpful or --verbose-debug flags and posting the verbose output the lists:> python simple_plot.py --verbose-helpful > output.txt
If you compiled matplotlib yourself, please also provide
any changes you have made to setup.py or setupext.py
the output of:rm -rf build python setup.py build
The beginning of the build output contains lots of details about your platform that are useful for the matplotlib developers to diagnose your problem.
your compiler version – eg, gcc --version
Including this information in your first e-mail to the mailing list will save a lot of time.
You will likely get a faster response writing to the mailing list than filing a bug in the bug tracker. Most developers check the bug tracker only periodically. If your problem has been determined to be a bug and can not be quickly solved, you may be asked to file a bug in the tracker so the issue doesn’t get lost.
First make sure you have a clean build and install (see How to completely remove matplotlib), get the latest git update, install it and run a simple test script in debug mode:
rm -rf build rm -rf /path/to/site-packages/matplotlib* git pull python setup.py install > build.out python examples/pylab_examples/simple_plot.py --verbose-debug > run.out
Of course, you will want to clearly describe your problem, what you are expecting and what you are getting, but often a clean build and install will help. See also Getting help. | <urn:uuid:3cda4a69-943d-4675-af29-2e20fbf670bd> | 2.671875 | 870 | Customer Support | Software Dev. | 50.984302 | 2,128 |
The trivial ring, or zero ring, is the ring with a single element, which is both and . We usually denote the trivial ring as or , even though or would make as much sense. It is the only ring in which , by the proof
x = 1 x = 0 x = 0 .
The trivial ring is the terminal object in Ring. It is both terminal and initial (hence a zero object) in the category of nonunital rings, but it is not initial in itself (defined as the category of unital rings and unital ring homomorphisms). In fact, there are no unital ring homomorphisms from the trivial ring to any nontrivial ring!
The trivial ring is an example of a trivial algebra. | <urn:uuid:8bf3cc72-0d62-43cb-9094-dd700a025e2b> | 3.21875 | 153 | Knowledge Article | Science & Tech. | 64.258898 | 2,129 |
A scientists’ work is never done.
That’s because there’s always another layer to peel away, another stone to turn, another angle from which to view the situation. Case in point—nearly 200 years ago, Charles Darwin made the connection between the size and shape of a finch’s beak and the availability of the seeds they eat; to this very day, no one has been able to produce evidence that undermines his observation and the conclusions he drew from them.
But what if there’s more to a beak than meets the eye?
That’s the question raised by Russell Greenberg of the Smithsonian Conservation Biology Institute. His theory—that beak size may also be an adaptation to temperature regulation and water conservation—has been bolstered by data from two recently published studies. [Data collected, in part, by a newly minted PhD named Ray Danner. Ray just happens to be a member of my own adopted extended family, and if that name sounds vaguely familiar… well, regular NDN readers may remember that not too long ago I was bragging about another member of this ornithological power couple, Ray’s wife, Dr. Julie Danner.]
Some years back, Greenberg noticed a difference in size between the beaks of sparrows living in salt marshes and those of sparrows settled just a kilometer or two further inland. Then a paper published in 2009 reported toco toucans (Ramphastos toco) may lose as much as 60% of their body heat through their long bills, based on thermal imaging and similar to the role played by the large ears of both elephants (Elephantidae) and jackrabbits (Lepus spp.). While many ecologists assumed toucans were a special case, Greenberg wondered—might other birds have evolved larger or smaller beaks to discharge or conserve heat as well?
He chose to test his hypothesis by applying thermal imaging to a subject with a much less prominent proboscis—the song sparrow (Melospiza melodia). Native to North America, everything about these feathered minstrels is miniature compared to their South American kin. The toucan weighs in at 1-2 pounds (the large bill doesn’t actually tip the scale as much as you might think since it’s mostly hollow) while at 0.4—1.9 ounces the song sparrow is definitely a featherweight.
In the first study, two subspecies were examined. On average, the beak of an Atlantic song sparrow was found to have 17% more surface area than that of the eastern song sparrow, although both birds have similarly sized bodies. Based on the Greenberg team’s calculations, the Atlantic sparrow loses 33% more heat than it’s inland neighbor. The finding suggests beaks may play a role in thermoregulation for a wide variety of bird species.
The ability to stay cool when the ambient temperature rises is critical to survival, but how one gets rid of the excess heat is just as important. Birds don’t sweat—they pant… and lose not just heat but water in the process. This summer, residents across the U.S. have been reminded just what a precious resource water can be, and never more so than for all the creatures without easy access to a faucet. Greenberg and his colleagues suggest that a bird’s beak can function like a radiator, releasing heat without losing water. The Atlantic sparrow’s larger bill saves the bird about 8% more water than the smaller beaked eastern sparrow. That may not sound like much but during a hot, dry summer it could be a significant survival advantage.
The second study examined museum specimens of song sparrows collected on the other side of the continent, along the California coast. Sure enough, as maximum temperatures increase, so did beak size… with one caveat. When the maximum temperature was higher than 98°F (37°C) beaks got smaller… just as was predicted by the original hypothesis. You see, if you took a song sparrow’s temperature the thermometer would read about 105°F (41°C). When the air temperature exceeds the bird’s own temperature, as it does in some regions, a larger beak could actually begin to absorb heat.
While the Smithsonian group has demonstrated a connection between climate and beak size, there’s still plenty of work to be done. For the new hypothesis to garner support, scientists need to see data that ties survival of wild birds to beak size-related heat dissipation.
Meanwhile, the fact that diet influences beak size and shape hasn’t changed—Darwin can continue to rest in peace. But as so often is the case, the more we discover the more we realize just how rich and complex this world and its inhabitants are … even an Earthling as seemingly plain and simple as a sparrow.
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© 2012 Next-Door Nature—no reprints without written permission from the author (I’d love for you to share my work; all you have to do is ask). Thanks to these photographers for making their work available through a Creative Commons license: [from the top] Ame Otoko (toco toucan); Cephas (song sparrow); James Marvin Phelps (black-tailed jackrabbit); Mr. T in DC (house sparrow on drinking fountain); David Craig (song sparrow in hand). | <urn:uuid:8922c58c-0634-4ff8-be88-8e8a3575fc81> | 3.59375 | 1,183 | Personal Blog | Science & Tech. | 50.639129 | 2,130 |
Four jewellers possessing respectively eight rubies, ten saphires,
a hundred pearls and five diamonds, presented, each from his own
stock, one apiece to the rest in token of regard; and they. . . .
A, B & C own a half, a third and a sixth of a coin collection.
Each grab some coins, return some, then share equally what they had
put back, finishing with their own share. How rich are they?
Pick a square within a multiplication square and add the numbers on
each diagonal. What do you notice?
A paradox is a statement that seems to be both untrue and true at the same time. This article looks at a few examples and challenges you to investigate them for yourself.
We have exactly 100 coins. There are five different values of
coins. We have decided to buy a piece of computer software for
39.75. We have the correct money, not a penny more, not a penny
less! Can. . . .
Write down a three-digit number Change the order of the digits to
get a different number Find the difference between the two three
digit numbers Follow the rest of the instructions then try. . . .
What does logic mean to us and is that different to mathematical logic? We will explore these questions in this article.
When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...
These formulae are often quoted, but rarely proved. In this article, we derive the formulae for the volumes of a square-based pyramid and a cone, using relatively simple mathematical concepts.
The sums of the squares of three related numbers is also a perfect
square - can you explain why?
This jar used to hold perfumed oil. It contained enough oil to fill
granid silver bottles. Each bottle held enough to fill ozvik golden
goblets and each goblet held enough to fill vaswik crystal. . . .
Spotting patterns can be an important first step - explaining why it is appropriate to generalise is the next step, and often the most interesting and important.
Can you find all the 4-ball shuffles?
This addition sum uses all ten digits 0, 1, 2...9 exactly once.
Find the sum and show that the one you give is the only
Find the missing angle between the two secants to the circle when
the two angles at the centre subtended by the arcs created by the
intersections of the secants and the circle are 50 and 120 degrees.
The problem is how did Archimedes calculate the lengths of the sides of the polygons which needed him to be able to calculate square roots?
Here are some examples of 'cons', and see if you can figure out where the trick is.
Baker, Cooper, Jones and Smith are four people whose occupations
are teacher, welder, mechanic and programmer, but not necessarily
in that order. What is each person’s occupation?
Take any two numbers between 0 and 1. Prove that the sum of the
numbers is always less than one plus their product?
Find the area of the annulus in terms of the length of the chord
which is tangent to the inner circle.
I am exactly n times my daughter's age. In m years I shall be exactly (n-1) times her age. In m2 years I shall be exactly (n-2) times her age. After that I shall never again be an exact multiple of. . . .
Can you convince me of each of the following: If a square number is
multiplied by a square number the product is ALWAYS a square
Factorial one hundred (written 100!) has 24 noughts when written in full and that 1000! has 249 noughts? Convince yourself that the above is true. Perhaps your methodology will help you find the. . . .
If you take two tests and get a marks out of a maximum b in the first and c marks out of d in the second, does the mediant (a+c)/(b+d)lie between the results for the two tests separately.
Use the numbers in the box below to make the base of a top-heavy
pyramid whose top number is 200.
The country Sixtania prints postage stamps with only three values 6 lucres, 10 lucres and 15 lucres (where the currency is in lucres).Which values cannot be made up with combinations of these postage. . . .
If you know the sizes of the angles marked with coloured dots in
this diagram which angles can you find by calculation?
There are four children in a family, two girls, Kate and Sally, and
two boys, Tom and Ben. How old are the children?
Consider the equation 1/a + 1/b + 1/c = 1 where a, b and c are
natural numbers and 0 < a < b < c. Prove that there is
only one set of values which satisfy this equation.
In the following sum the letters A, B, C, D, E and F stand for six
distinct digits. Find all the ways of replacing the letters with
digits so that the arithmetic is correct.
Semicircles are drawn on the sides of a rectangle ABCD. A circle passing through points ABCD carves out four crescent-shaped regions. Prove that the sum of the areas of the four crescents is equal to. . . .
Let a(n) be the number of ways of expressing the integer n as an
ordered sum of 1's and 2's. Let b(n) be the number of ways of
expressing n as an ordered sum of integers greater than 1. (i)
Calculate. . . .
Points A, B and C are the centres of three circles, each one of
which touches the other two. Prove that the perimeter of the
triangle ABC is equal to the diameter of the largest circle.
Carry out cyclic permutations of nine digit numbers containing the
digits from 1 to 9 (until you get back to the first number). Prove
that whatever number you choose, they will add to the same total.
Janine noticed, while studying some cube numbers, that if you take
three consecutive whole numbers and multiply them together and then
add the middle number of the three, you get the middle number. . . .
Eight children enter the autumn cross-country race at school. How
many possible ways could they come in at first, second and third
Here are three 'tricks' to amaze your friends. But the really
clever trick is explaining to them why these 'tricks' are maths not
magic. Like all good magicians, you should practice by trying. . . .
Six points are arranged in space so that no three are collinear.
How many line segments can be formed by joining the points in
What is the area of the quadrilateral APOQ? Working on the building
blocks will give you some insights that may help you to work it
I start with a red, a green and a blue marble. I can trade any of
my marbles for two others, one of each colour. Can I end up with
five more blue marbles than red after a number of such trades?
Nine cross country runners compete in a team competition in which
there are three matches. If you were a judge how would you decide
who would win?
From a group of any 4 students in a class of 30, each has exchanged
Christmas cards with the other three. Show that some students have
exchanged cards with all the other students in the class. How. . . .
A standard die has the numbers 1, 2 and 3 are opposite 6, 5 and 4
respectively so that opposite faces add to 7? If you make standard
dice by writing 1, 2, 3, 4, 5, 6 on blank cubes you will find. . . .
A little bit of algebra explains this 'magic'. Ask a friend to pick 3 consecutive numbers and to tell you a multiple of 3. Then ask them to add the four numbers and multiply by 67, and to tell you. . . .
I start with a red, a blue, a green and a yellow marble. I can
trade any of my marbles for three others, one of each colour. Can I
end up with exactly two marbles of each colour?
Arrange the numbers 1 to 16 into a 4 by 4 array. Choose a number.
Cross out the numbers on the same row and column. Repeat this
process. Add up you four numbers. Why do they always add up to 34?
A 'doodle' is a closed intersecting curve drawn without taking
pencil from paper. Only two lines cross at each intersection or
vertex (never 3), that is the vertex points must be 'double points'
not. . . .
Can you fit Ls together to make larger versions of themselves?
How many different cubes can be painted with three blue faces and
three red faces? A boy (using blue) and a girl (using red) paint
the faces of a cube in turn so that the six faces are painted. . . .
A connected graph is a graph in which we can get from any vertex to
any other by travelling along the edges. A tree is a connected
graph with no closed circuits (or loops. Prove that every tree. . . . | <urn:uuid:cecfc178-7e3d-44c4-97c5-0ea96f190d58> | 2.828125 | 1,998 | Content Listing | Science & Tech. | 75.944028 | 2,131 |
25 January 2011
Posted in NatureWorks
New Cloning Experiment Makes Big News
The discovery of a frozen Mammoth has allowed a team of Japanese Scientists an attempt at cloning the species. Yes, a real life Mammoth could be walking the planet after 10,000 years of extinction.
Researchers plan to use a tissue sample from frozen mammoth remains, to harvest cell nuclei. The nuclei of the mammoth cell will then be inserted into the egg cell of an elephant, which has had its own nuclei removed. Follow? In other words… if we take an elephant egg cell, remove its nucleus, and then replace it with a mammoth nucleus, we will have a baby mammoth.
The research group, which includes two American, and one Russian scientist, is headed by Akira Iritani, professor at Kyoto University in Japan. | <urn:uuid:47a12f15-dbc4-40c3-a906-c403bb9294b1> | 3.390625 | 169 | News Article | Science & Tech. | 49.017941 | 2,132 |
The first stage of the Delta II rocket to be used to launch the Gamma-Ray Large Area Space Telescope, or GLAST, has arrived at Cape Canaveral, Fla.
GLAST will explore the most extreme environments in the universe, where nature harnesses energies far beyond anything possible on Earth, said Kevin Grady, the GLAST project manager. He said the telescope will be used to search for signs of new laws of physics and what composes the mysterious dark matter, explain how black holes accelerate immense jets of material to nearly light speed and help solve the mysteries of the enormously powerful explosions known as gamma-ray bursts.
GLAST is to be launched May 16 from the Kennedy Space Center.
The National Aeronautics and Space Administration plans to rename the observatory and has invited the public to submit name suggestions that can be an acronym but it isn't a requirement. The suggestions can be submitted through March 31 at
NASA said the GLAST mission is an astrophysics and particle physics partnership, developed with the U.S. Department of Energy and partners in France, Germany, Italy, Japan, Sweden and the United States.
Copyright 2008 by United Press International
Explore further: Field tests in Mojave Desert pave way for human exploration of small bodies | <urn:uuid:3ee540a9-edab-4862-b8b9-03c9a0a0a670> | 3.25 | 254 | News Article | Science & Tech. | 33.317456 | 2,133 |
A Matter of Relativity?
Copyright 2006/2007 James A. Tabb
Part 5: Entangled Particles
Selecting which atom we use with careful attention to its excitation states can create entangled particles. Some atoms emit two photons at a time or very closely together, one in one direction, the other in the opposite direction. These photons also have a property that one spins or is polarized in one direction and the other always spins or is polarized at right angles to the first. They come in pairs such that if we conduct an experiment on one to determine its orientation, the other’s orientation becomes known at once. They are “entangled”.
Figure 10 – Entangled Particles
All of this was involved in a famous dispute between Einstein and Bohr where Einstein devised a series of thought experiments to prove quantum measurement theory defective and Bohr devised answers. The weirdness, if you want to call it that, is the premise that the act of measurement of one actually defines both of them and so one might be thousands of miles away when you measure the first and the other instantly is converted, regardless of the distance between them, to the complement of the first.
Action-at-a-distance that occurs faster than the speed of light? Some would argue (me for instance) that this is more of a hat trick, not unlike where a machine randomly puts a quarter under one hat or the other, and always a nickel under a second one. You don’t know in advance which contains which. Does the discovery that one hat has a quarter actually change the other into a nickel or was it always that way? Some would say that since it is impossible to know what is under each hat, the discovery of the quarter was determined by the act of measuring (lifting the hat) and the other coin only became a nickel at that instant. Suppose one hat is in Chicago and the other in Paris. Is this action at a distance? It is easy to say that the measurement of the first particle only uncovers the true nature of the first particle and the deduction of the nature of the second particle is not a case of weirdness at all. They were that way at the start. However, this is a hotly debated subject and many consider this a real effect and a real problem. That is, they consider the particles (which are called Einstein‑‑ Podolsky‑Rosen (EPR) pairs) to have a happy-go-lucky existence in which the properties are undetermined until measured. Measure the polarization of one – and the second instantly takes the other polarization.A useful feature of entangled particles is the notion that you could encrypt data using these particles such that if anyone attempted to intercept and read them somewhere in their path, the act of reading would destroy the message.
So there you have it – Weird behavior at a distance, maybe across the universe. Or is it a matter of relativity?
I wish to suggest this: entangled particles are entangled at the time of emission and, from the relativistic perspective, they are still attached together at the point of emission until the time that one or the other is disturbed or destroyed, however far that is. Both ends of their flights are stapled together from the moment of their creation by relativistic space distortion. They both live in a go-splat world where time stands still and everything in their path is zero distance away and zero time lapse away due to the relativistic foreshortening of paths and time distortions to zero. In their time and distance collapsed world, if you can wiggle one, the other knows about it because they are both still stuck against their common emission point at one end until destroyed at the other. There can be “real world” time elapsed during flight (from our perspective) but the photon is running on null time – relativistic zero time and both are still attached to a common point with both ends separated by zero distance and zero time, even if we measure it at tens of meters and dozens of nanoseconds.
In Summary – Not So Weird After All
Photons and other particles that travel at c have paths that are effectively zero length and time spans that are of zero duration. This applies to the path length and lifetime of the particle due to relativistic space time warping at c. No matter how we measure the time and distance a particle travels in a real-world time frame, the particle has a simultaneous, instantaneous path and duration due to the warping of the space and time at c.
We measure the particle in flight at about a nanosecond a foot. No matter. The photon gets there instantaneously – no time elapses for the photon – no ageing takes place. That means no matter how many mirrors or detectors we flip into or out of a path during our calculated flight time, the photon, traveling at c, transverses the entire path in zero time over zero distance. Our perspectives are that different. Mirrors or detectors that are in the path at the time it reaches a certain point by our measurement, were experienced by the particle at the instant it was emitted. So it knows about it “in advance” due to the space time warp factor. It does transverse the experiment, but cannot be fooled as it knows the entire path the instant it is created.
Suppose a distant exploding star emits a photon that arrives at our telescope 4 billion years later (by our normal world calculation). The photon may pass around lensing galaxies on both sides at once because the entire path, including the incredible width of the galaxies, is of virtually zero width and zero depth to the photon which is traveling at c. The detector’s position, forward of a focal point or behind it, is also experienced by the photon during that same zero path, zero lifetime defining moment of creation, life, and death. All due to the incredible time and distance warp at c. So we think it is weird that the change in our detector, at or behind the focal point seems to affect the chosen path of the photon around the distant lensing galaxy. Not to the photon. It knew all along, since “all along” was an instantaneous null time and null distance, warped together.
Photons moving through a double slit experiment have all the elements in its path effectively (although not actually) plastered to its nose and all the elements have zero width and zero depth to the photon during its lifetime. From our perspective, we consider it moving through the experiment, encountering edges, slits, possibly mirrors or detectors. Whatever we throw in its path, the photon experiences it as if it were there from the moment of its creation because that is the only moment it has. All because it lives in a relativistic go-splat world.
Photons moving through crystals and reversed crystals see all the paths simultaneously and its entire flight path as one event – all happening simultaneously. All open paths are valid because they are essentially congruent, allowing the photons to retain their polarity if there are paths that maintain its ability recombine at the far end. If any path is broken by a detector when it would pass by in our real world measurement system, then it is encountered in its relativistic world during its null time existence.
Quantum Weirdness Is a Matter of Relativity!
James A. Tabb
Originally published among friends February 6, 2006 | <urn:uuid:ed503364-a5ea-4200-b20c-f11d77054894> | 3.828125 | 1,517 | Personal Blog | Science & Tech. | 42.35438 | 2,134 |
Series and parallel
|This is a series circuit, showing the location of an ammeter and voltmeter.
The current is the same at all points along the circuit
The sum of the voltage across the individual components is equal to that at the power supply.
|At the junctions, the current splits, but then rejoins at the final junction.|
Voltage across each component stays the same
Parallel circuits are used in christmas lights because, if one light breaks, the electricity will flow the other route.
This is an important relationship between voltage, resistance and current. It is very simple and outlined in a triangle below, where V = IR; and some units are explained. | <urn:uuid:641d1f77-2f8f-4eaa-ae24-6786f88ef182> | 3.71875 | 144 | Knowledge Article | Science & Tech. | 45.533176 | 2,135 |
Highest Magnification At The Highest Resolution With A Highly Powered Electron Microscope
The problem with magnifying an image boils down to two things: power and scale. First, will the magnifying instrument have enough power to condense reflected light and present a microscopic view of the same? Second, will such power be enough to produce a scale that is both clear and precise? These two requisites have been the problem of most microscope models throughout the centuries. Some models fail to possess the power required for the undertaking, and users are limited to a specific magnification level only. Some models were able to muster enough power to magnify the view of a specimen's surface, but the scale becomes too grainy to be studies with accuracy.
An electron microscope solves the need for both these requisites. Powered by highly charged electrons as opposed to conventional optic microscopes which are powered only by certain light sources, an electron microscope is capable of displaying images at amazing clarity even in the most magnified scales. Such a feature makes a lot of things possible:
* The texture of an object is preserved even at full magnification. This allows a closer study of the material properties of a specimen's surface.
* The physical features of the materials that make up the specimen's surface can be displayed with accuracy. Distinguishing and determining their type can be accomplished with more precision.
* The composition of the said materials can better be observed given the electron microscope's immense power.
* Subatomic levels can likewise be studied, and this will shed light on the actual make of certain materials.
An electron microscope derives its power from an electron source. Thereafter, it projects the same via a well-focused and highly concentrated beam guided by lenses and apertures unto the specimen being studied. The specimen is irradiated, and light at great degrees is reflected back to the observing eye. This gives a better view of the subject at a microscopic level.
Indeed, electron-powered microscopes emerged as solutions to the ever increasing limitations of optic microscopes. Whereas before, people were limited to viewing certain magnification, nowadays, electron makes very high magnifications at very high resolutions possible.
If you have the choice between an electron-powered microscope and the conventional variety, and if you're involved in an industry that requires meticulous precision and accuracy when it comes to empirical undertakings, then do choose the former. It may cost a little more than optical microscopes, but the benefits you will receive from the same will serve you better in the long run.
Martinsburg, Secaucus, Hinesville, Concord, Freeport, Roanoke, Richmond, Hialeah, Alabaster, Imperial Beach, Northlake, West Virginia, Pennsylvania, New Jersey, South Dakota, Oroville, California, Salem, Fremont, Lewiston, Claremont, Covina, Independence, Keokuk, Lynchburg, Keene, Pascagoula, Florence, Agawam, Cutler Bay, West Plains, Douglasville, San Diego, Rochester, Homestead, Fort Payne, Merced, Delaware, Bangor, Pinecrest, Kenosha, Downers Grove, Colorado, Fort Atkinson, Waynesboro, Portland, South Carolina, Rancho Santa Margarita, Sugar Hill, Massachusetts, Montgomery, Porterville, West Chester, Fitchburg, Crawfordsville, Gainesville, Scottsdale, McKinney, Gloucester City, Moses Lake, Altus, North Miami Beach, Shelbyville, Lake Station, Jacinto City, West Point, Oak Harbor, Burlington, Cheyenne, Aberdeen, Midland, Topeka, Coralville, Paterson, Payson, Portales, Arkansas, Cary, Poquoson, Fairhope, Weatherford, Fairmont, Naperville, St. Matthews, Janesville, Cocoa, Gainesville, Eunice | <urn:uuid:7d86b41c-4352-45cc-8c01-575e6b2da62f> | 3.484375 | 788 | Product Page | Science & Tech. | 12.311507 | 2,136 |
Deadly Sea Snakes: Alike But Not The Same
December 3, 2012
The lethal beaked sea snake is actually two species which separately evolved to give identical snakes.
AsianScientist (Dec. 3, 2012) – Researchers from Australia and Indonesia have discovered that the lethal beaked sea snake (Enhydrina schistosa) is actually two species with separate evolutions, which resulted in identical snakes.
Senior author Associate Professor Bryan Fry from The University of Queensland said the Australian and Asian beaked sea snakes were originally thought to be from the same species, however, in comparing their DNA, the research team had found these two snakes were unrelated.
Analyses of five independent mitochondrial and nuclear loci for populations spanning Australia, Indonesia, and Sri Lanka indicate that this ‘species’ actually consists of two distinct lineages in Asia and Australia that are not closest relatives.
The finding, published recently in the journal Molecular Phylogenetics & Evolution, is an example of a situation where two species evolved separately but ended up looking similar – a phenomenon known as convergent phenotypic evolution, says Fry.
Convergence in the characteristic ‘beaked’ morphology of these species is probably associated with the wide gape required to accommodate their spiny prey, he explained, as both species occupy the same specialized habitat of silt-filled shallows of tropical estuaries throughout the Asian and Australian regions.
The beaked sea snake is also responsible for the large majority of recorded deaths and injuries from sea snake bites.
Fortunately, the only available sea snake anti-venom available – raised against the Malaysian E. schistosa – is also effective against the new Australian species.
“This mixup could have been medically catastrophic, since the CSL sea snake antivenom is made using the venom from the Asian snake based on the assumption that it was the same species,” said Fry. “Luckily, the antivenom is not only very effective against the Australian new species but actually against all sea snakes since they all share a very stream-lined fish-specific venom.”
The Asian snake will retain the original name Enhydrina shistosa, while its Australian counterpart has been elevated to species status and is provisionally referred to as Enhydrina zweifeli, which identifies the region in New Guinea where it is found.
The new snake will be placed in a separate genus to the true Enhydrina genus in a follow-up publication that will resolve the complex higher order relationships of sea snakes.
Source: University of Queensland.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff. | <urn:uuid:0df15ac9-0a2b-4202-95e3-6bca37248f92> | 3.390625 | 548 | News Article | Science & Tech. | 14.855618 | 2,137 |
Einstein couldn't wrap his mind around quantum physics, why should we try? Because there are explantations that make sense out of a nonsensical world; because there are perspectives that clarify mysteries; because it is fun!
But that trick won't work with a normal flashlight. You need a laser pointer split by a prism! :)
A flashlight won't work because the light isn't coherent. A LASER POINTER WILL work. Here's what you do:
I should mention, I did this very experiment in college physics lab, something over 40 years ago.
Kindly note: doing the same thing with electrons is CONSIDERABLY HARDER!
Perhaps it could be done with a Scanning Electron Microscope. I'd consider trying if I weren't retired.
No, but as Loren said, it still can be done at home! As a bonus, your cat will love the laser pointer! I know mine do! :D
I wasn't able to open this link, but copied and pasted the title and came up with this most interesting film. Morgan Freeman walks us through an experiment by Yves Couder and I get a shiver running up and down my spine. Particle and wave co-exist! COOL! indeed!
My 9-year-old son is ... well, he's my son, he's a geek. In my travels through his science education I've found a few absolutely brilliant gems
The first book I got for my daughter - I think of it as "A Brief History of Time" for kids: http://www.amazon.co.uk/Time-Universe-Whats-Big-Idea/dp/0340655909 - I cannot rave enough about this book (that's my 2002 review... I'm still keen on it!)
That book helps to set the stage for this one: http://www.amazon.com/This-Strange-Quantum-World-You/dp/1577330358
Stephen and Lucy Hawking have a series out - we only have one of them, but it's not bad: http://www.amazon.com/Georges-Secret-Universe-Stephen-Hawking/dp/14...
Now - time for the big keyboard confessional. I learned how to explain these mind-blowing concepts so much easier (because I understood them more) after these kids books... just sayin'...
Very cool! I can't wait to indoctrinate my kids with this same stuff! :D
Aristotle might have meant "All men desire to claim to know."
More years ago than I want to count, while in college, I read of Aristotle's claim that women have fewer teeth than men.
About 2K years passed before someone with access to the media counted teeth and found Aristotle wrong.
Observing photons changes their reality?
Observing politicians changes their behavior and changes observers' beliefs. | <urn:uuid:8c032d1f-c375-4171-906a-133f61b2ee6c> | 2.625 | 605 | Comment Section | Science & Tech. | 75.938871 | 2,138 |
Discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field.
I'll quote from now on. I just came here to seek possible answers to questions concerning our origins. I need clarification. What is accepted scientific explanation? I've heard strong and credible scientist propose all kinds of theories but they range from DNA occurring from a chemical reaction caused by commentary gases coalescent with Earth, to repressive proteins that would normally obstruct replication, but somehow gave rise to areas in replication that created new strands. I'm not into religion but I have a sneaking suspicion that perhaps there are more complex answers seldom visited, but equally plausible. DNA requires RNA and proteins, but proteins also require RNA and DNA . There's also something else I'm wondering about: Genetic markers show (seemingly) irrelevant - 'junk' DNA, held over from previous evolutionary changes or adaptations - the thing that I don't understand is that alterations in DNA are almost always fatal. We are so genetically different from Neanderthal that we couldn't have produced offspring with them, and the fossil record shows that they abruptly ceased and Cromagdon was introduced, rapidly - much too rapidly for the known chronological scale of development required for evolution. What I've been taught since high school is that there was some anomaly resident to the proteins and RNA that ignited self replication – but again, any changes to genetic architectures are usually fatal to the organism. It's as if everything I think of in explanation is paradoxical, hence negated by what (or which) came first. Sorry to ask so much. By the way, these questions aren't challenges, I'm sincere and I'm just wondering if you or someone else could give me some insight.
It likely was protein that came first, as it's a more simple structure, but I'm not going to recap the whole thread (nobody wants that).
The experiment you're describing specifically (the Miller-Urey experiment of gases in the atmosphere) is no longer the "dominant" theory, but it shares the same basis as the current one: that amino acids necessary for life formed from components and conditions already found on Earth at that time. No one (at least not from any theory I've ever heard) has posited that DNA or RNA suddenly formed before amino acids, or anything of the sort.
Proteins don't require DNA and RNA, they could potentially just form from amino acids, which can form from their component bases. However RNA may have arisen, it doens't have to be a circular paradox with DNA.
And you're providing the explanation to your question right along with it. The changes to genetic architecture are usually fatal; that means not always. It's exactly the same along with evolution. Most mutations aren't expressed, and of the ones that are the results are often irrelevant or crippling or fatal. But the ones that work spread into a population, because they benefit the organism. So no matter how many fatal changes there may have been, it only would take one change that worked to create a new mechanism.
As for the 'junk' DNA, it's not necessarily a holdover from previous generations. It's called a teleomer, and it's non-coding DNA, essentially it does nothing. Every time that DNA is replicated, it cuts off a small amount of DNA on the teleomer, slowly moving towards the coding DNA at the top of the strand. As long as there is DNA on the teleomer it's fine, but once you run out of it you start to lose coding DNA, and some proteins suddenly stop being produced. So it does serve a purpose, just not the same purpose as the rest of your DNA.
I'm not 100% sure specifically what you mean about the Cromagdon, could you clarify this?
I hope I helped with some of your questions. Oh and one minor thing, could you break up your posts a bit, so it's not just one huge lump of text?
Not Much to add to what Khaly said, but ...
There is nodefinitive conclusion on how life appeared on earth, you can read the thread on abiogenesis in this forum for more detail. But the RNA world seem definitely to have the lead for the most likely. Until a more convincing hypothesis come out, of course.
I guess Cromagdon stand for Cro-Magnon. As far as I know (but I am not a specialist of human paleontlogy) they are 2 branches of the human family. And Cro=magnon, our ancestor, wiped out the neanderthal. Why? who knows...
Junk DNA is definitely a misnomer, we don't know why it's here, but it may not be such a junk. Telomere are a good example but account for only a part of its role. Other roles have also been suggested such as spacer between genes allowing a regulation of expression.
As for the danger of mutation, the neutralist theory was suggesting that most of the mutation are indeed silent. not fatal, and even if this theory is loosing its appeal, this still stand true. And some other work suggest that some chaperone proteins could buffer some of the more significant mutations (not the stop one though, but the one changing proteins structure). This allow some interesting speculation about a molecular mechanism for punctuated equilibrium too.
Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
I put this question to my lecturer and we were lost in this topic for nearly 2 hours. We also could not decide which actually came first since one requires the other for formation. We just came to the conclusion that, initially there was a giant pool or chemicals from which simpler stuff like amino acids, sugar molecules etc were formed with the help of some processes. maybe lightning or something, then the next simpler one RNA and then DNA and proteins.
We also came to another interesting solution that proteins came first. From the great pool already discussed, enzymes were formed which were required for various process like transcription, translation, replication and maybe reverse transcription. And according to someone (I do not remember) all enzymes are proteins, and so thus proteins came first.
Either way we hopelessly contradicted ourselves and we decided it was not important what came first, and it ended there.
Lot good things told here...
'which came first?' even if we know it , we be rarely applying or using it except our test on evolution topic! BUT the process of finding out answer, even if much slow, would give many intellectual insights and lot of knowledge about "the earth earlier" & these qualities and knowlede is not only useful in predicting future but also in any field which requires intelligent thought as getting answer to this question is a really a great exersise to out tinanimous brains!!!
But finding the past seems "the exersize unending" because there is always a yesterday to a yesterday ...i.e. yesterday always lies there behind...
when you guys keep on saying protein came first, do you mean peptide chains? Cause a fully functional protein has to fold with the tertiary structures. Only a few simple proteins will just form on their own. The complex enzymes usually need other enzymes and chaperone proteins and perhaps a working ER to do this.
The reason behind RNA being the first is because RNA can also form into ribozymes, simple enzymes that can catalyze peptide synthesis.
I have been thinking about this thing too.. In a biochemistry course we must write an essay about which one of these three came first. The essay should be 2 sides of a A4 paper, not longer than that.. It's just hard to think what to write. Our instructions say there is no wrong or no right answer. But as I just said it's still hard to know what to write and where to start from.. Any ideas? Maybe I find some ideas by reading through this thread?
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Even yellow journalists know it’s a good idea to use the refereed scientific literature as the basis for science stories, so it was disconcerting to see a bona fide green journalist like the Washington Post’s Joby Warrick give a great deal of ink to a nonrefereed speech - not even a paper - delivered in San Francisco by federal climatologist Jonathan Overpeck.
The reason for all the fuss soon became obvious. At the December meeting of the American Geophysical Union, Overpeck said that the so-called Medieval Warm Period was local, not global. In other words, the warming that was so substantial that it allowed the Vikings to colonize Greenland and North America was not created by a general planetary warming. That implies that the cooling that followed - known as the Little Ice Age - was similarly non-global; otherwise the Warm Period would have shown up, in comparison with temperatures in succeeding centuries as, well, global warming.
Overpeck’s speech prompted handsprings of joy from our greener friends. Now, instead of saying that the decade of the 1990s (and, in particular, 1998) is the warmest in 600 years (which goes back to the beginning of the putative Warm Period), they can say it’s the warmest in 1,200 years. This story will be in print on or about January 4, 1999, and allows them to declare that the warm terror is here and higher taxes are needed pronto to stop the burning of fossil fuels.
Others might say, “big deal, sure am glad that I haven’t spent a lick on heating oil and it’s almost Christmas. Think I’ll go and buy some stuff for the missus.”
Like Tip O’Neill’s politics, climate is local.
Still others may correctly deduce that Overpeck has created a big problem for those who warn of impending apocalypse. If he is right (a large IF), then regional climate naturally varies tremendously, whether or not the globe warms. In other words, climate changes so dramatic that they promoted the Viking exploration are simply the way of things. And ditto for their flipside - large regional coolings like the Little Ice Age. That event sent the Rhone Glacier in the Alps some 5,000 feet further downslope than it is today and prompted winter carnivals on the frozen Thames.
Poignant testimony to the social consequences of this regional swing can be found in Kalaallit Nunaat (the politically correct term for Greenland these days), where masonry churches, once built in pastures, are now encased in ice. While KN’s climate clearly changed in ways that were tremendously important to society at the time of the Vikings, that apparently had nothing to do with global warming or cooling.
Instead, Overpeck says, those changes occurred as purely internal oscillations of the climate system, with no external global change. If we accept that notion, what does it really mean?
It means that large, regional climate changes have occurred and will occur whether or not the planet warms. That is the kind of change people and plants care about, because no one can sense the global temperature. Like Tip O’Neill’s politics, climate is local. So those who would seek to impose costs on society to prevent climate change had better demonstrate that warming the planet will make large regional excursions more, not less, likely.
Recently, I explored this notion in a paper in the refereed journal Climate Research. Relying upon historical data (and explicitly ignoring computer models of climate because of their patent unreality), I found that temperature variability between seasons and between years has significantly declined in the second half of this century. And there have been a few warm years in that period, too.
So when I looked at the variability as a function of the planet’s annual temperature, I found that the cool years were more variable and the warmer ones less. Conclusion? Warming the planet decreases variability on a year-to-year scale. Cooling the planet makes things more variable.
That’s pretty good evidence that what human beings are doing to the climate makes things more predictable and equable than before.
Want more? When the carbon dioxide concentration of the atmosphere was at its highest level since animals first appeared, the biggest animals in history roamed the earth: dinosaurs. Those beasts required a tremendous amount of vegetation to reach their enormous size. Carnivores, like T. Rex, were supported by the massive herbivores. How many tons of vegetation were ultimately required to feed them, considering it had to pass through huge lunks like Apatosaurus (that’s Brontosaurus to you intellectual dinosaurs)? The toasty earth had to have been greener than casino felt.
What’s more, when the dinos were around, the climate was so stable that they were cold blooded! They’d probably still be here today, except for the fact that they went extinct when the earth got clobbered by a small asteroid. The asteroid raised a huge cloud of dust and killed them with global cooling, which made the climate more variable, resulting in an undependable food supply.
Our greener friends might become extinct too, if they tout Overpeck’s findings as good news for their side. | <urn:uuid:12321856-431d-4d11-88d8-1829bbf304cf> | 2.6875 | 1,111 | Nonfiction Writing | Science & Tech. | 44.923813 | 2,140 |
SPOT Tags are one of the most advanced technology tags used by researchers. Like the other types of tags, it records a variety of measurements, such as temperature, salinity, and depth. However, powered by a very powerful transmitter, SPOT Tags regularly send their recorded data to satellites. These tags are primarily designed for use on animals that are commonly found at the ocean's surface, where regular broadcast to a satellite is possible. Therefore, they are suited for use on dolphins, turtles, seals, and any other animal that must spend at least some regular time at the ocean surface. Recently, these tags have been successfully placed on the dorsal fin of sharks that swim at the surface. These tags are fairly expensive and require large batteries to power them. To save battery power, some tags are fitted with a switch that turns them off when they become submerged under water, turning back on when the tag comes to the surface where it transmits again.
A Smart Position and Temperature Tag. (Tagging of Pacific Pelagics - TOPP)
A SPOT Tag being placed on the dorsal fin of a salmon shark. (Tagging of Pacific Pelagics - TOPP) | <urn:uuid:f9340695-cef5-4a6a-8f64-dc017996d681> | 3.453125 | 238 | Knowledge Article | Science & Tech. | 37.332547 | 2,141 |
Exercise Template Haskell
In this exercise, we will have a closer look at Template Haskell. The hierarchical libraries
that are distributed with GHC include functions for writing Template Haskell code. Have a look
at the modules Language.Haskell.TH
You may want to consult the notes on Template Haskell
and Section 7.6
from the GHC User's Guide.
To use Template Haskell code from the ghci interpreter, you need to use the flag
This exercise was inspired by research on automatically repairing ill-typed expressions. For some typical programming errors,
a more advanced compiler could offer advise to a programmer how to correct an expression with a type error. In fact, the
offers such a facility. You are asked to write a number of functions that
can be used to correct an expression (details are given below).
You are given two Haskell modules as a starting point.
- Correct.hs: contains the functions you have to define. Currently, these functions are set to
- Test.hs: contains a number of functions for testing your implementation. In some cases, the expected answer is provided. In the other cases, the test corresponds to an optional question. Note that you also have to make changes to this module because the compiler must be informed about which parts are meta-programs.
Submit your solution by sending me the two changed Haskell modules, and give short
answers to the questions posed. Good luck!
1. Removing an argument
The following expression contains a type error.
test0 = filter even () [1..10]
One possibility to get rid of the type error is removing the
from the application. We will use the following convention:
corresponds to the function of the application (
to its first argument (
), etc. Implement a function
that is given a number
(greater than or equal to
), such that it conceptually ignores the
(remove 2) filter even () [1..10]
should yield the same result as
filter even [1..10]
n = 2
write a (lambda) expression by hand that behaves as
- Why can't
remove be defined as a normal (non-Template) Haskell function?
remove n with
n = 0 is a special case, since it removes the function of an application rather than some argument. Give an intuition for the meaning of
- What happens if we choose
n = 5 for the example presented above (the function
filter is supplied only three parameters)?
2. Inserting an argument
In the following expression, the higher-order function
should be given an initial value.
This expression can be repaired by inserting a second parameter.
test2 = foldr ((:) . toUpper) "afp 2005"
We will use the same convention for assigning numbers to the parameters.
(insertHole 2) foldr ((:) . toUpper) "afp 2005"
should be equal to
foldr ((:) . toUpper) hole "afp 2005"
is the polymorphic "error function" predefined in the module
Optional part for 2:
More ideally, we pass an additional parameter to
, which is the value to be inserted. For instance,
(insert 2 ) foldr ((:) . toUpper) "afp 2005"
foldr ((:) . toUpper) "afp 2005"
. Explain your solution.
3. Permuting arguments
In the next example, the arguments to
are supplied in the wrong order.
test4 = foldr 0 (+) [1..10]
A permutation can be represented by a value of type
. For instance, the permutation
swaps the first and the second
argument of a function. Give an implementation of
for permuting arguments.
- Explain the difference between
permute [0,2,1] and
- The value
[0,1,1] is not a valid permutation, but it can be passed to
permute. What kind of corrections can we make by passing invalid permutations?
4. Inserting parentheses
Take a look at the following expression.
test5 = length filter even [1..10]
A common mistake made in functional programming is to forget some parentheses. The expression given above can be fixed by inserting two parentheses,
length (filter even [1..10])
. This is the purpose of the function
that you have to write.
This function should be supplied two integers: the first indicates the location of the opening parenthesis, the second integer indicates how many
parameters are enclosed by the parentheses. We use the convention that location
corresponds to the position just before the function
(in our example,
corresponds to the position between the function and its first argument (in our example, between
, we thus need
parens 1 3
- What can you say about the values of the two integers that can be supplied to
parens? Are there special cases?
5. Removing parentheses (optional)
In a similar way, we would like to remove a pair of parentheses.
foldr ((++) ["Template", "Meta", "Programming"])
Following our line of reasoning, we could fix the type error by using
unparens 1 3
. Can you give a definition for
6. Library for correcting expression
Template Haskell offers a facility to splice in declarations. Therefore, we could automatically bring the functions
, etcetera into the top-level scope of a module. These specialized functions can be used as any normal Haskell function.
Of course, we can make use of the general
function (see Step 2).
Bring (a limited number of) specialized functions for
into the scope.
Optional part for 6:
Do the same for the other correcting functions.
7. Extending the library (optional)
Of course, there are more mistakes resulting in a type error that can be fixed automatically.
Can you think of more (useful) correcting functions? | <urn:uuid:7a7d3605-cf73-43fb-8116-8c8e8341ec29> | 2.78125 | 1,273 | Tutorial | Software Dev. | 53.184547 | 2,142 |
February 9, 2000
Java Programming, Lecture Notes # 302
by Richard G. Baldwin
This lesson is primarily concerned with the use of the java.awt.geom.Point2D class. It also illustrates the use of nested top-level classes in the Java 2D Graphics API. This is a concept that was explained in an earlier tutorial lesson. If you aren’t familiar with this concept, you should review the earlier tutorial that explains it.
The concept of a point is central to most graphics models. A point is a specification of a particular location in space. It has neither height, nor width, nor depth. Therefore, it cannot be rendered on your computer screen, although it might be possible to render a pixel on your screen that occupies a space generally specified by the point.
Although points can exist in three-dimensional space, that is not our interest in the current series of lessons. This series of lessons in concerned with the Java 2D (two-dimensional) API. Hence, a point in our 2D space represents a location in that space commonly specified by a pair of coordinate values, horizontal (x) and vertical (y).
You may already be familiar with the notion of performing graphic operations in Cartesian coordinates. This is similar, except in Cartesian coordinates, the positive direction of y-displacement is normally up, while in our current frame of reference, the direction of positive y-displacement is down. As in typical Cartesian coordinates, the direction of positive x-displacement is to the right.
So, an object of the java.awt.geom.Point2D class encapsulates a pair of coordinate values that specify a location in our coordinate system. Many of the graphic objects that we will encounter later as we continue to pursue the Java 2D Graphics API are constructed on a foundation of points. For example, four points could be used to specify the corners of a rectangle, and three points could be used to specify the apexes of a triangle. A large number of points could be used to specify a curved line made up of many short straight-line segments.
The Point2D class demonstrates the use of nested top-level classes, which is an inheritance concept used throughout the 2D API. This is a concept where one or more subclasses are defined as static classes inside their superclass. The details of this concept were presented in an earlier tutorial lesson.
While an object of the Point2D class encapsulates the coordinates of a location in space, that class alone doesn’t specify how the coordinate values are stored. Rather, two nested subclasses named Point2D.Double and Point2D.Float are used to actually store the coordinate information. An object of the first subclass stores the coordinate information as type double while an object of the second subclass stores the coordinate information as type float. Apparently, however, it is usually satisfactory to treat those objects as type Point2D, because many of the standard methods that use an object of the type Point2D will determine the actual subclass type and then behave accordingly.
The Java 2D API became available with the release of JDK 1.2. Prior to that time, the Java AWT included a class named Point that could also be used to specify the coordinates of a location in space. Objects of the Point class have, since the beginning, specified the coordinate values as type int, and that is still the case. With the release of the 2D API, the Point class now extends the Point2D class. However, Point is not a nested subclass of Point2D. It is simply a subclass of Point2D.
The Point2D class provides several methods that are inherited by its subclasses, and can be used to operate on objects instantiated from those subclasses. Most of the methods have several overloaded versions. Generally the methods provide the following capabilities:
The sample program that I will present later will make use of some of these capabilities.
The two nested subclasses provide (apparently overridden versions of) the set and get methods for setting and getting the coordinate values as the appropriate type. The Point2D.Float class provides set methods for input parameters of either type double or type float. Presumably if the coordinate values are provided as type double, they are converted to type float and saved as that type.
Curiously, the get methods of the Point2D.Float class do not provide an overridden version to return coordinate values of type float. Rather, they return the coordinate values as type double even if this means returning inaccurate double results. This is illustrated in the sample program that I will present later.
Both of the nested subclasses provide an overridden toString() method that returns a String that represents the type of object and the coordinate values of the point.
The Point class provides methods to accomplish generally the same behavior as described above for the new classes in the 2D API, although in some cases the syntax is different. In addition, the Point class provides methods to
Since the Point class is not new to the Java 2D API, I probably won’t have much to say about it in this series of lessons. The biggest difference between the Point class, which has existed since JDK 1.0, and the Point2D class that was released with JDK 1.2 is:
The sample program presented later will illustrate the use of the nested subclasses named Point2D.Double and Point2D.Float.
This sample program, named Point01.java is designed to illustrate the use of the two nested top-level classes that are contained in, and extend the class named Point2D. I will break the program into fragments for discussion. A complete listing of the program is provided at the end of the lesson.
The first fragment (Figure 1) shows an import directive to remind us that we are working with a class that belongs to the java.awt.geom package.
This fragment also shows the beginning of the definition of the controlling class named Point01. Two instance variables are declared, each of type Point2D. Later, these instance variables will be used to contain references to two objects, one of each of the nested subclass types.
Figure 2 shows the beginning of the main() method. This fragment also shows the instantiation of an object of the controlling class, and the storage of a reference to this object in the local reference variable named thisObj. This object contains the two instance variables of type Point2D declared above, which can be used to refer to objects of the nested subclass types.
Figure 3 instantiates an object of the nested subclass, Point2D.Double and stores a reference to that object in an instance variable named doublePointVar, which is an instance variable of the object of the controlling class (thisObj). Note that this reference variable is not of the actual type of the object, but rather is of the type of its superclass named Point2D. This is possible because in Java, a reference to an object can be stored in a reference variable of the actual class of the object, or of any superclass of the class of the object.
When the new object of the Point2D.Double class is instantiated, the x and y coordinate values are initialized with the following values respectively:
At least these would be the values if we had infinite precision. In reality, these values are stored in the object with the precision afforded by the double type
Similarly, Figure 4 instantiates an object of the Point2D.Float class, and stores its reference in a different instance variable of the controlling class named floatPointVar. Again, this variable is not of the actual type of the object, but rather is of the superclass of the object, Point2D.
This is a common theme used throughout the Java 2D API. Objects are frequently instantiated from a nested subclass type and the references to those objects are stored in reference variables of the superclass type.
When this object is instantiated, its coordinate values are initialized with the same values described above (never ending 3’s and 6’s) except that in this case, the values are stored with precision afforded by the float type, which is considerably less than the precision afforded by the double type.
Note that a (float) cast is required to force the result of the division to be of type float in order to satisfy the parameter type requirements of the constructor for the Point2D.float class.
Figure 5 applies the getX(), and getY() methods to the two instance variables containing references to the two objects of the nested-subclass types to get and display the coordinate values stored in those objects.
The output produced by this code fragment follows:
Data from the object of type Point2D.Double
Data from the object of type Point2D.Float
As mentioned earlier, the get methods for the Point2D.Float class return the stored coordinate information as type double. However, as you can see, the returned values are not accurate beyond about the seventh significant digit in this case (I have highlighted the erroneous values in red). The double values returned by the get method for the Point2D.Double class are accurate through about sixteen significant digits.
This fragment also ends the main() method and ends the controlling class.
A listing of the complete program is provided in Figure 6
Richard Baldwin is a college professor and private consultant whose primary focus is a combination of Java and XML. In addition to the many platform-independent benefits of Java applications, he believes that a combination of Java and XML will become the primary driving force in the delivery of structured information on the Web.
Richard has participated in numerous consulting projects involving Java, XML, or a combination of the two. He frequently provides onsite Java and/or XML training at the high-tech companies located in and around Austin, Texas. He is the author of Baldwin's Java Programming Tutorials, which has gained a worldwide following among experienced and aspiring Java programmers. He has also published articles on Java Programming in Java Pro magazine.
Richard holds an MSEE degree from Southern Methodist University and has many years of experience in the application of computer technology to real-world problems.
Copyright 2000, Richard G. Baldwin. Reproduction in whole or in part in any form or medium without express written permission from Richard Baldwin is prohibited. | <urn:uuid:db027679-2a28-4a09-bf01-fb86ea8daeba> | 4.21875 | 2,134 | Truncated | Software Dev. | 46.206797 | 2,143 |
CAMBRIDGE, Mass. -- A team of scientists at MIT have discovered a previously unknown phenomenon that can cause powerful waves of energy to shoot through minuscule wires known as carbon nanotubes. The discovery could lead to a new way of producing electricity, the researchers say.
The phenomenon, described as thermopower waves, "opens up a new area of energy research, which is rare," says Michael Strano, MIT's Charles and Hilda Roddey Associate Professor of Chemical Engineering, who was the senior author of a paper describing the new findings that appeared in Nature Materials on March 7. The lead author was Wonjoon Choi, a doctoral student in mechanical engineering.
Like a collection of flotsam propelled along the surface by waves traveling across the ocean, it turns out that a thermal wave — a moving pulse of heat — traveling along a microscopic wire can drive electrons along, creating an electrical current.
The key ingredient in the recipe is carbon nanotubes — submicroscopic hollow tubes made of a chicken-wire-like lattice of carbon atoms. These tubes, just a few billionths of a meter (nanometers) in diameter, are part of a family of novel carbon molecules, including buckyballs and graphene sheets, that have been the subject of intensive worldwide research over the last two decades.
In the new experiments, each of these electrically and thermally conductive nanotubes was coated with a layer of a highly reactive fuel that can produce heat by decomposing. This fuel was then ignited at one end of the nanotube using either a laser beam or a high-voltage spark, and the result was a fast-moving thermal wave traveling along the length of the carbon nanotube like a flame speeding along the length of a lit fuse. Heat from the fuel goes into the nanotube where it travels thousands of times faster than in the fuel itself. As the heat feeds back to the fuel coating, a thermal wave is created that is guided along the nanotube. With a temperature of 3,000 kelvins, this ring of heat speads along the tube 10,000 times faster than the normal spread of this chemical reaction. The heating produced by that combustion, it turns out, also pushes electrons along the tube, creating a substantial electrical current.
Combustion waves — like this pulse of heat hurtling along a wire — "have been studied mathematically for more than 100 years," Strano says, but he was the first to predict that such waves could be guided by a nanotube or nanowire and that this wave of heat could push an electrical current along that wire.
In the group's initial experiments, Strano says, when they wired up the carbon nanotubes with their fuel coating in order to study the reaction, "lo and behold, we were really surprised by the size of the resulting voltage peak" that propagated along the wire.
After further development, the system now puts out energy, in proportion to its weight, about 100 times greater than an equivalent weight of lithium-ion battery.
The amount of power released, he says, is much greater than that predicted by thermoelectric calculations. While many semiconductor materials can produce an electric potential when heated, through something called the Seebeck effect, that effect is very weak in carbon. "There's something else happening here," he says. "We call it electron entrainment since part of the current appears to scale with wave velocity."
The thermal wave, he explains, appears to be entraining the electrical charge carriers (either electrons or electron holes) just as an ocean wave can pick up and carry a collection of debris along the surface. This important property is responsible for the high power produced by the system, Strano says.
Because this is such a new discovery, he says, it's hard to predict yet exactly what the practical applications will be. But he suggests that one possible application would be in enabling new kinds of ultra-small electronic devices — for example, a devices the size of grains of rice, perhaps a sensor or treatment device that could be injected into the body. Or it could lead to "environmental sensors that could be scattered like dust in the air," he says.
In theory, he says, such devices could maintain their power indefinitely until used, unlike batteries whose charge leaks away gradually as they sit unused. And while the individual nanowires are tiny, Strano suggests that they could be made in large arrays in order to supply significant amounts of power for larger devices.
One area the researchers plan to pursue is the fact that their theory predicts that using different kinds of reactive materials for the coating, the wave front could oscillate, thus producing an alternating current. That opens up a variety of possibilities, Strano says, because alternating current is the basis for radio waves such as cell phone transmissions, but present energy-storage systems all produce direct current. "Our theory predicted these oscillations before we began to observe them in our data," he says.
Also, the present versions of the system have low efficiency, because much power is being given off as heat and light. The team plans to work on improving that efficiency.
Funding: Air Force Office of Scientific Research, and the National Science Foundation
Written by David Chandler, MIT News Office
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system. | <urn:uuid:686e38e2-d99d-4ea2-99b3-20fa849d2b0f> | 3.734375 | 1,131 | News Article | Science & Tech. | 34.028759 | 2,144 |
The James Webb Space Telescope marked another year of significant progress in 2012 as flight instrumentation was completed and delivered to NASA.
The year brought forth the delivery of two types of flight mirrors, the Mid-Infrared Instrument (MIRI), the Fine Guidance Sensor and Near-Infrared Imager and Slitless Spectrograph (FGS/NIRISS), and the completion of the center section of the primary mirror backplane. The Webb project modified the historic Chamber A at NASA's Johnson Space Center, Houston, Texas, to enable the Webb telescope's optics and instrument systems to be tested. In addition to the telescope and test chambers coming together, spinoff technology from the Webb has already been used in industries to improve people's lives.
On Sept. 17, 2012, two primary mirror segments that will fly aboard NASA's James Webb Space Telescope arrived at NASA's Goddard Space Flight Center in Greenbelt, Md. The flight secondary mirror and a third primary mirror segment arrived at NASA Goddard on Nov. 5, 2012, and are currently being stored in the giant clean room. All of the mirrors are made of beryllium, which was selected for its stiffness, light weight and stability at extremely cold cryogenic temperatures. Bare beryllium is not very reflective at Webb's shortest wavelengths, so each mirror is coated with gold. The microscopic gold coating enables the mirrors to efficiently reflect infrared light (which is what the Webb telescope's cameras see).
The Mid-infrared Instrument (MIRI) flight hardware was delivered to NASA's Goddard Space Flight Center on May 28 2012, for integration into the ISIM. The MIRI will allow scientists to study cold and distant objects in greater detail than ever before and with unprecedented sensitivity. MIRI will observe light with wavelengths in the mid-infrared range of 5 microns to 28.5 microns, which is longer wavelength than human eyes can detect. Of Webb's four instruments, MIRI is the only one that works at the longest wavelengths. MIRI will be integrated into Webb's science instrument payload known as the Integrated Science Instrument Module (ISIM). An international team of European scientists and engineers collaborated with JPL to produce this instrument.
The second of four instruments to fly aboard NASA's James Webb Space Telescope was delivered to NASA Goddard on July 30. The Fine Guidance Sensor (FGS) will enable the telescope to accurately and precisely point at the correct targets. The FGS is packaged together as a single unit with the Near-Infrared Imager and Slitless Spectrograph (NIRISS) science instrument. The FGS/NIRISS will also be integrated into Webb's ISIM.
The FGS consists of two identical cameras that will allow the telescope to determine its position, locate its celestial targets, and remain pointed to collect high-quality data. The FGS will guide the telescope with incredible precision, with an accuracy of one millionth of a degree of angle. Although the NIRISS is packaged with the FGS, it is functionally independent. NIRISS provides unique capabilities that will aid in finding the earliest and most distant objects in the Universe's history. It will also peer through the glare of nearby stars to detect and study planets in other Solar Systems. The FGS/NIRISS was developed by the Canadian Space Agency.
The center section of the Webb telescope's flight backplane structure that will fly on the Webb telescope was completed in April, 2012. The structure will support twelve of the eighteen beryllium mirrors, thermal control systems and other elements during ground tests, launch and during science operations. Measuring approximately 24 by 12 feet yet weighing only 500 pounds, the center section of the backplane meets unprecedented thermal stability requirements. The center section is the first of the three sections of the backplane to be completed.
Chamber A Completed
For three years, engineers at NASA's Johnson Space Center in Houston, Texas have been building and remodeling the interior of Chamber A, the largest thermal vacuum chamber in the world, so it will meet the temperature requirements to test the Webb. They installed a gaseous helium cooling system that brought the interior of the chamber down to 11 degrees kelvin above absolute zero (-439.9 F/-262.1C). Chamber A testing will confirm that the telescope and science instrument systems will perform properly together in the cold temperatures of space. Additional test support equipment includes mass spectrometers, infrared cameras and television cameras so that engineers can keep an eye on the Webb while it's being tested.
New technologies developed for NASA's James Webb Space Telescope have already been adapted and applied to commercial applications in various industries including optics, aerospace, astronomy, medical and materials. Some of these technologies can be explored for use and licensed through NASA's Office of the Chief Technologist at NASA's Goddard Space Flight Center, Greenbelt, Md.
For example, the optical measuring technology developed for the Webb, called "wavefront sensing" has been applied to eye health and has allowed improvements in measurement of human eyes, diagnosis of ocular diseases and potentially improved surgery.
The powerful primary mirrors of the James Webb Space Telescope will be able to detect the light from the first luminous objects that formed when the universe was young, as well as distant galaxies and nearby stars and their planets. Altogether, 21 mirrors comprise the Webb's telescope optics -- 18 primary mirror segments working together as one large 21.3-foot (6.5-meter) primary mirror, the secondary mirror mounted on a tripod above the primary mirror, and the tertiary mirror and the fine steering mirror that are both located inside an assembly near the center of the primary mirror.
The most powerful space telescope ever built, the Webb telescope will provide images of the first galaxies ever formed, and explore planets around distant stars. It is a joint project of NASA, the European Space Agency and the Canadian Space Agency.
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system. | <urn:uuid:b7857f4c-0dcf-4d86-9add-386c3196080f> | 3.421875 | 1,247 | News (Org.) | Science & Tech. | 38.263733 | 2,145 |
Kew's Millennium Seed Bank partnership - Slovakia
Kew's Millennium Seed Bank partnership with Slovakia is helping to conserve threatened species across three bio-geographic regions.
ENSCONET field trip to Slovakia 2011
Plant life in Slovakia is under threat
Although a relatively small country, Slovakia possesses a surprising richness in biodiversity. Biodiversity is the diversity of life on Earth, including every plant, animal and micro-organism.
Highlights of Slovakian biodiversity include a number of endemic plant species found only in the Carpathian mountains of Slovakia, such as tatra chamois (Rupicapra rupicapra subsp. tatrica) or tatra marmot (Marmota marmota subsp. latirostris). Amongst its patchwork of woodland and meadows, Slovakia is also home to one of the richest areas in Europe for insects.
Overall, approximately 3,350 taxa of ferns and flowering plants are currently known from Slovakia. A taxon (plural taxa), is a group of living things at a particular level of classification, for example a species, family or class. Out of these taxa, 124 plant species are considered critically endangered, 273 are endangered and 350 are vulnerable.
Almost 15% (488) of the 3,350 taxa of ferns and flowering plant species known from Slovakia have been reported as endemic and more than 6% (220) of them can be found only in the Carpathian mountain region. Overall 779 endemic or threatened plant taxa are protected by law.
The main threats to Slovakian plant species and their habitats are driven by human activities, including over-exploitation of plant species, urban development, pollution, climate change and, in particular, conversion of species-rich meadows and pastures into intensively managed grasslands. As a result of drainage, dams, agricultural runoff and industrial pollution, the most endangered habitats in Slovakia are aquatic and wetland ecosystems.
The critically endangered marsh gladiolus (Gladiolus palustris) once thrived in the Slovakian wetland meadows but now remains in one nature reserve. Similarly the yellow flowered endemic turna golden drop (Onosma tornensis) and sweetly scented muran daphne (Daphne arbuscula) have also declined in number and are now critically endangered.
Biogeographic regions in Slovakia
Biogeography is the study of the distribution of biodiversity in different locations, over time. It aims to reveal where organisms live, and at what quantity. One reason that the diversity of plant life in Slovakia is interesting is because three areas, distinctly different in their landscape, geology and subsequent biodiversity meet within the country's borders. These regions are the Alpine, Continental and Pannonian.
The Alpine regions are high mountains with high light levels and large fluctuations in temperature. The Continental areas are mostly forests and peatlands in the northern part of country. In Slovakia the Pannonian region consists mainly of dry lowlands with stepe grasslands as well as wetlands important for migrating birds.
The Western part of the Carpathian Mountains, which belong to the Alpine biogeographic region, is the most species rich area of Slovakia. The influence of the Pannonian biogeographic region is apparent only in the southernmost part of Slovakia, where many Pannonian endemic plant species reach their northernmost distribution point. Populations of these species may be particularly vulnerable to climate change as the lack of suitable habitat prevents them from colonising north.
Almost 10% of the Slovak flora is already banked and saved for the next generations and available for environmental restoration, or for reintroduction programmes.Prof. Karol Marhold, Institute of Botany, Slovak Academy of Science
Saving seeds for the future in Slovakia
Because of its rich plant diversity, and the number of plant species identified as under threat, Kew's Millennium Seed Bank partnership is working with Slovakia to help save plant life at risk. A Memorandum of Collaboration between the Kew and the Institute of Botany, Slovak Academy of Sciences was signed in December 2006, demonstrating our commitment.
Our collecting programme covers the whole of Slovakia and we focus our activity on protecting plant species that are unique to this region, or endangered as a result of human impact and activity.
During the last four collecting seasons, seed collectors from the Institute of Botany have saved the seeds of 411 plant species, out of which 60 are identified as endangered, 58 as vulnerable and 65 as critically endangered.
Thirty one of the collected taxa are unique to the Carpathians, and twelve plant species are only found in the Pannonian region. All seed collections are currently stored at Kew's Millennium Seed Bank, located at Wakehurst Place, as well as in the Gene Bank of the Slovak Republic in Piešťany.
ENSCONET Collecting trip
During 2011 a joint ENSCONET field trip was made in Slovakia. To find out more about the Slovakian field trip visit the ENSCONET Slovakia Field Trip Image Gallery.
Get involved - Adopt a Seed, Save a Species
We have successfully banked 10% of the world's wild plant species and we have set our sights on saving 25% by 2020.
Without plants there could be no life on earth, and yet every day another four plant species face extinction. Too often when we hear these kind of statistics there is little that we can do as individuals, but thanks to Kew's Millennium Seed Bank partnership and the Adopt a Seed, Save a Species campaign there is something that you can do to ensure the survival of a plant species.
Discover more about our work across Europe...
Our Slovakian team
- Clare Trivedi, International Co-ordinator
- Jonas Mueller, International Co-ordinator
- Ruth Eastwood, Partnership Assistant
Our partners in Slovakia
Keep up to date with events and news from Kew | <urn:uuid:564714ea-367d-45b3-8144-05ab209a678c> | 3.21875 | 1,237 | About (Org.) | Science & Tech. | 29.708373 | 2,146 |
Floating on air
Question: I have been told that if I lie on an air mattress near to the shore, it will always tend to drift out to sea, even when there is no wind. Is this true? If so, why?
Answer: It is not necessarily true. It depends on the combination of currents, wave patterns and, most markedly, the wind. However, some things do bias towards a seaward drift. Incoming surf has little impact on a smooth, light, high-floating bubble like an air mattress, so it cannot give the mattress much of a push. Increasing the wave's speed does not improve the "grip" on the mattress. And the faster the mattress is moved, the greater the air resistance on it.
Long curling waves (combers) tend to come in fast and high and, to a lesser extent, so do broken waves as they roll in. Such waves pass quickly, so ...
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UCLA biologists report how whales have changed over 35 million years
By Stuart Wolpert May 28, 2010 Category: Research
Whales are remarkably diverse, with 84 living species of dramatically different sizes and more than 400 other species that have gone extinct, including some that lived partly on land. Why are there so many whale species, with so much diversity in body size?
To answer that, UCLA evolutionary biologists and a colleague used molecular and computational techniques to look back 35 million years, when the ancestor of all living whales appeared, to analyze the evolutionary tempo of modern whale species and probe how fast whales changed their shape and body size. They have provided the first test of an old idea about why whales show such rich diversity.
"Whales represent the most spectacularly successful invasion of oceans by a mammalian lineage," said Michael Alfaro, UCLA assistant professor of ecology and evolutionary biology, and senior author of the new study, which was published this month in the early online edition of Proceedings of the Royal Society B and will appear at a later date in the journal's print edition. "They are often at the top of the food chain and are major players in whatever ecosystem they are in. They are the biggest animals that have ever lived. Cetaceans (which include whales, as well as dolphins and porpoises) are the mammals that can go to the deepest depths in the oceans.
"Biologists have debated whether some key evolutionary feature early in their history allowed whales to rapidly expand in number and form," Alfaro said. "Sonar, large brains, baleen (a structure found in the largest species for filtering small animals from sea water) and complex sociality have all been suggested as triggers for a diversification, or radiation, of this group that has been assumed to be rapid. However, the tempo — the actual rate of the unfolding of the cetacean radiation — has never been critically examined before. Our study is the first to test the idea that evolution in early whales was explosively fast."
One explanation for whale diversity is simply that they have been accumulating species and evolving differences in shape as a function of time. The more time that goes by, the more cetacean species one would expect, and the more variation in body size one would expect to see in them.
"Instead, what we found is that very early in their history, whales went their separate ways from the standpoint of size, and probably ecology," Alfaro said. "This pattern provides some support for the explosive radiation hypothesis. It is consistent with the idea that some key traits opened up new ways of being 'whale-like' to the earliest ancestors of modern cetaceans, and that these ancestors evolved to fill them. Once these forms became established, they remained."
Species diversification and variations in body size were established early in the evolution of whales, Alfaro and his colleagues report.
Large whales, small whales and medium-sized whales all appeared early in the history of whales, with the large whales eating mostly plankton, small whales eating fish and medium-sized whales eating squid.
"Those differences were probably in place by 25 million years ago at the latest, and for many millions of years, they have not changed very much," said the study's lead author, Graham Slater, a National Science Foundation–funded UCLA postdoctoral scholar in Alfaro's laboratory. "It's as if whales split things up at the beginning and went their separate ways. The distribution of whale body size and diet still corresponds to these early splits."
"The shape of variation that we see in modern whales today is the result of partitioning of body sizes early on in their history," Alfaro said. "Whatever conditions allowed modern whales to persist allowed them to evolve into unique, disparate modes of life, and those niches largely have been maintained throughout most of their history.
"We could have found that the main whale lineages over time each experimented with being large, small and medium-sized and that all the dietary forms appeared throughout their evolution, or that whales started out medium-sized and the largest and smallest ones appeared more recently — but the data show none of that. Instead, we find that the differences today were apparent very early on."
Killer whales are an exception, having become larger over the last 10 million years, Alfaro and Slater said. Killer whales are unusual in that they eat mammals, including other whales.
"If we look at rates of body-size evolution throughout the whale family tree, the rate of body-size evolution in the killer whale is the fastest," Slater said. "It came from the size of a dolphin you would see at SeaWorld about 10 million years ago and grew substantially."
Whales range in size from the largest animal known to have ever existed, the blue whale, which is more than 100 feet long, to small species that are about the size of a dog and can get caught in fishermen's nets, Slater said.
Alfaro and Slater do not find evidence for rapid whale diversification, but extinctions may have made it difficult to detect early rapid diversification.
Whales are about 55 million years old, but the first group of whales to take to water is extinct, Alfaro said. Different hypotheses have been proposed to explain the rapid appearance and diversification of modern whales, which coincided with the extinction of the primitive whales.
Before the extinction of the dinosaurs 65 million years ago, there were large marine reptiles in the oceans that went extinct. When the earliest whales first went into the oceans some 55 million years ago, they had essentially no competitors, Alfaro and Slater noted. These primitive whales ranged in size from several feet to 65 feet long and looked similar to land animals, Slater said. They all fed on fish; the earliest whales did not dive deep down to catch squid.
Alfaro's laboratory uses many techniques, including the analysis of DNA sequences, computational techniques and the fossil record to analytically test ideas about when major groups appear and when they become dominant. He and his research team integrate information from the fossil record with novel computational methods of analysis.
"We are interested in understanding the causes of biodiversity," Alfaro said.
"If we really want to understand species diversity, the number of species in any given group and how the variation in body size came to be, this paper points out that we will need to rely on more of a collaboration between paleontologists and molecular biologists to detect possible changes in the rate at which new species came into existence," Slater said.
The analytical tools for integrating the fossil data with the molecular data are just being developed, said Alfaro, whose research is bridging the divide.
Co-authors on the Proceedings of the Royal Society B study are Samantha Price, a postdoctoral scholar at UC Davis, and Francesco Santini, a UCLA postdoctoral scholar in Alfaro's laboratory.
The research is federally funded by the National Science Foundation (NSF) and by the NSF-funded National Evolutionary Synthesis Center.
Proceedings of the Royal Society B is a leading British journal for biological sciences research.
For more on Alfaro's research, visit his website at http://pandorasboxfish.squarespace.com/.
UCLA is California's largest university, with an enrollment of nearly 38,000 undergraduate and graduate students. The UCLA College of Letters and Science and the university's 11 professional schools feature renowned faculty and offer more than 323 degree programs and majors. UCLA is a national and international leader in the breadth and quality of its academic, research, health care, cultural, continuing education and athletic programs. Five alumni and five faculty have been awarded the Nobel Prize. | <urn:uuid:32580198-6880-414b-b792-d63cf69c318a> | 3.734375 | 1,570 | News (Org.) | Science & Tech. | 31.455287 | 2,148 |
Physical Sciences Division
The Oxygen Squeeze Play
Scientists first to discover tetraoxygen on the surface of a common catalyst
Oxygen molecules fill reactive pockets on the surface of rutile titanium dioxide. When heated, they split apart, with one oxygen staying put and the other filling a nearby vacancy (Top). When oxygen is added at low temperatures, two oxygen molecules fit into the vacancy. When heated, these molecules form a new species, tetraoxygen. Enlarged View
Results: When it gets cold on the surface of a popular catalyst, four oxygen atoms squeeze into a spot designed for just one, according to scientists at Pacific Northwest National Laboratory. Initially, the atoms are paired up as two oxygen molecules or
2 O2. But, when the temperature rises, the two molecules react to form a new species, tetraoxygen or O4.
Why it matters: If researchers want to design a catalyst from scratch or improve an existing one, they need to predict how oxygen will react with the surface, said PNNL's Greg Kimmel, the principal investigator on the project. This very fundamental study revealed new information that will help predict oxygen interactions.
Methods: The researchers exposed a sample of rutile titanium dioxide or TiO2(110) to different amounts of oxygen at very low temperatures. Then, they heated the sample and studied the behavior of the oxygen using electron-stimulated desorption and mass spectrometry techniques.
The researchers began with a catalyst whose surface contained scattered reactive pockets, or vacancies, where oxygen atoms had left the surface. Next, they added (or adsorbed) molecular oxygen to see how it would interact with the reactive pockets. The oxygen was adsorbed at about 25 K or -414 degrees Fahrenheit, which required cooling the sample with liquid helium. In one experiment, they added one oxygen molecule per oxygen vacancy. In a second experiment, they added two oxygen molecules per vacancy.
For both experiments, no oxygen was released from the surface as it was heated. Instead the molecules reacted on the surface, but the type of reactions depended on whether the vacancies had one or two oxygen molecules.
For the sample with one molecule per vacancy, the oxygen molecule began to split apart at 150 K: one oxygen atom stayed put filling the vacancy, and the other adsorbed at nearby site on the surface. By 280 K, all of the oxygen had filled in surface vacancies.
However, when the sample that initially had two O2 per vacancy was heated above 200 K, these molecules transformed to tetraoxygen - a 4-atom arch poking up from the reactive pockets. By 500 K, the tetraoxygen decomposed, filling in nearby reactive pockets. But, to drive off all the oxygen and restore the vacancies, the scientists had to heat the sample to 700 K, about the temperature used to bake bread.
What's next? This fundamental research leads to more questions about the behavior of the common oxygen molecule on the catalyst's surface. The researchers plan to continue their research.
Acknowledgments: This research was done by Greg Kimmel and Nikolay Petrik at PNNL. The DOE Office of Basic Energy Sciences, Chemical Sciences Division funded the research.
Experiments were performed in the electron and photon stimulated desorption laboratory located in DOE's EMSL, a national scientific user facility at PNNL.
The work supports PNNL's mission to strengthen U.S. scientific foundations for innovation by developing tools and understanding required to control chemical and physical processes in complex multiphase environments.
Reference: Kimmel GA and NG Petrik. 2008. "Tetraoxygen on Reduced TiO2(110): Oxygen Adsorption and Reactions with Bridging Oxygen Vacancies." Physical Review Letters 100, 196102. DOI: 10.1103/PhysRevLett.100.196102. | <urn:uuid:bbb30bb8-6b0c-48b1-a0f0-13778be4931b> | 3.9375 | 796 | Knowledge Article | Science & Tech. | 37.715785 | 2,149 |
Enough fossil fuels to fry us all
George Monbiot said in a recent article that "We were wrong about peak oil. There is enough to fry us all". He is wrong on peak oil, but right with his general conclusion. There are enough fossil fuels to fry us all.
Will peak oil save us from global warming? Can it be that the decline of oil production caused by scarcity will be more effective than the (feeble) attempts made by governments to reduce greenhouse gas emissions?
This point was debated briefly this year the conference of the Association for the Study of Peak Oil (ASPO) in Vienna. It is a typical controversy of ASPO conferences: some people seem to be so oil centered that they think that the climate models of the International Panel on Climate Change (IPCC) are all wrong because they don't take into account the ASPO data. The latest manifestation of this peculiar delusion comes from George Monbiot who decided that peak oil is not coming so soon, after all, and so concluded that "We were wrong about peak oil, there is enough to fry us all."
Now, we can say that Monbiot is wrong: first of all because he gives too much credit to an optimistic recent study on oil production (and even misinterpreting it - if you read it carefully, the data of the study are not so optimistic. See here and here for a critical assessment)
But the real mistake made by Monbiot is to over-emphasize the importance of peak oil for climate change. So far, the vagaries of oil production haven't affected so much the trend of the emissions of greenhouse gases. Today, even though crude oil production has been flat for several years, carbon dioxide emissions keep increasing.
That's what you'd expect: oil is just one of the sources of extra CO2 in the atmosphere and the increasing costs of extraction are pushing the industry to use dirtier fuels. In other words, we are seeing a trend towards using fuels which release more CO2 for the same amount of energy generated. In this sense, tar sands, heavy oil, oil shales, and the like are all dirtier than oil. Coal is even worse and it is also the fastest growing energy source in the world. To say nothing of the emissions of methane by fracking, (methane is a much more powerful greenhouse gas than carbon dioxide).
So, why should we expect peak oil to make a difference? Paradoxically, if peak oil were to come tomorrow, we might see CO2 emissions increase even more as that would cause an even more massive use of coal, tar sands, and other dirty sources. It is true that, eventually, the declining energy yield (EROEI) of fossil fuels will cause a general decline of greenhouse gas emissions; but we shouldn't expect that to be very soon and it won't be the immediate consequence of peak oil.
If we continue with the present trends of fossil fuel production, we risk to make climate change irreversible if we pass the "tipping point", the point of non return, which we may well have passed already. If peak oil had to have an effect on climate (maybe), it should have come at least 20 years ago when CO2 concentrations were still around 350 ppm, said to be the upper limit to avoid irreversible climate change. Now, at 400 ppm and growing, peak oil is not enough to stop global warming.
So, in the end George Monbiot is wrong on peak oil, but right on his general conclusion. We only have to modify it a little, as "Peak oil or no peak oil, there are enough fossil fuels to fry us all". | <urn:uuid:8c3a0d20-9ae6-4744-982b-34f3600f1834> | 2.9375 | 749 | Nonfiction Writing | Science & Tech. | 50.558654 | 2,150 |
This is simple java programming tutorial . In this section you will learn how to calculate the sum of three numbers by using three static variables.
Description of this program:
In this section we will see how to calculate three integer number . First of all define class name "StaticSum". For this we have defined three static variables of type int. To assign the value of the numbers define a method main. Remember we are overloading the main method. This method will take three arguments. The values will be added in the Addition method which we have declared in our program. Now call the main method. To get the values of the three numbers call the overloaded method main() inside main() method. To add those values call the Addition method which will return the integer value and the value will be displayed to the user by using the println() method of the System class.
Here is the code of this program
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:397d6c3f-0bb4-4203-b5ef-0cd1b457eb19> | 4.3125 | 225 | Tutorial | Software Dev. | 59.506731 | 2,151 |
The Myriad Forms of Alternate Energy
The need for renewable sources of energy is critical. Energy use skyrockets, fossil fuels gradually disappear, and we (Americans, especially) cross our fingers and hope that our way of life might continue. The huge concerns about the polluting nature of fossil fuels has become subsumed by the concern that fossil fuels have or will soon become an energy sources which is simply unavailable.
The problem of peak oil is the biggest concern of the moment. In brief, it's the reality that as oil supplies diminish, the work required to extract remaining oil increases. As a result, we expend more energy resources to acquire more energy resources. So the question isn't "how much oil is left?" Instead, we have to ask how much oil we'll need to use in order to extract the remaining resources.
But this isn't an article about the peak oil crisis or fossil fuels: it's about alternative energy sources.
Following a recent article describing an idea to use children's playground equipment for energy production in Africa, the obvious conclusion comes to mind: why just Africa? There's a huge focus on providing renewable energy resources in areas such as Africa largely because we can't readily afford to divert fossil fuels into those communities. They can't afford to buy it, and we can't afford to give it away.
But, in the long term, we won't be able to afford our own existing resources. This idea, taking an existing tool (or toy!) and using it for energy production is extremely sensible.
Although it's unlikely that children playing could produce enough power to keep the grid afloat (although I've known some children with a lot of energy,) children are far from the only way that our day-to-day activities could be converted into power production. Take the gym. Many people, as a result of their day to day sedendary office jobs, dedicated a portion of their available time to exercise. Why couldn't a stationary bike be a generator?
Finding alternate energy sources isn't just about creating gigantic wind farms, solar energy factories, or finding new way of extracting fuel from grass (an inherently flawed idea, as it is.) Renewable energy needs to be about finding ways of minimizing our daily energy use and finding whatever ways we can to create other energy sources.
We haven't yet found a single fuel source which is as efficient as fossil fuels in the sheer generation of energy - and it may well be that we never will. Finding numerous small resources and personal energy generation may be the only sustainable path.
Updated by Joe Dolson on 24 August, 2009 | <urn:uuid:54c36ad1-3aa3-43fa-a40e-a13c1b7094a8> | 2.546875 | 528 | Personal Blog | Science & Tech. | 45.420564 | 2,152 |
The script can be reduced in code for general usage and without comments it is only a few lines.
The advantages of using a script:
- The output format can be customized.
- It can be written to output the statistic either to a message box, a new file, to output window, or even into the file itself.
- The statistic output can be produced also for the entire file, or only selected text, or for selected text and entire file.
- The word delimiters can be customized and it is possible to filter the word list before counting, for example to ignore strings with a single character like a or I.
Summarized, using a script gives a user with good skills in writing scripts the possibility to customize the statistic output to personal needs. If such a customization is not required or a user has no skills in writing scripts, calling the word count tool is definitely the better solution. | <urn:uuid:53ffa54e-32aa-4afe-aacc-10f55492a3f7> | 2.8125 | 187 | Comment Section | Software Dev. | 42.351529 | 2,153 |
The past year saw a mild winter give way to a balmier-than-normal spring, followed by a sweltering summer and high temperatures that lingered into the fall, all punctuated by extreme drought and intense storms.
Now 2012 is officially in the books as the hottest year on record for the continental United States and the second-worst for "extreme" weather such as hurricanes, droughts or floods, the U.S. government announced Tuesday.
The year's average temperature of 55.3 degrees Fahrenheit across the Lower 48 was more than 3.2 degrees warmer than the average for the 20th century, the National Oceanographic and Atmospheric Administration reported. That topped the previous record, set in 1998, by a full degree.
Every state in the contiguous United States saw above-average temperatures in 2012, with 19 of them setting annual records of their own, NOAA said. Meanwhile, the country faced 11 weather disasters that topped $1 billion in losses each, including a lingering drought that covered 61% of the country at one point.
That drought shriveled crops across the American farm belt, leading to an expected rise in food prices in 2013, according to the U.S. Agriculture Department. It also turned forests of the mountain West into stands of tinder that exploded into catastrophic wildfires over the summer, scorching millions of acres and destroying hundreds of homes.
And then there was Superstorm Sandy, a late October post-tropical cyclone that killed more than 110 people in the United States and nearly 70 more in the Caribbean and Canada. Damage estimates from the storm run around $80 billion in New York and New Jersey alone.
The report is likely to fuel new concerns over a warming climate. Seven of the 10 hottest years in U.S. records, which date back to 1895, and four of the hottest five have now occurred since 1990, according to NOAA figures.
The year also saw Arctic sea ice hit a record low in more than 30 years of satellite observations and studies that found the world's major ice sheets have been shrinking at an increasing rate.
Scientists are quick to point out that no single storm can be blamed on climate change, but say a warming world raises the odds of extreme weather.
"I think unfortunately, 2012 really may well be the new normal," said Daniel Lashof, director of the climate and clean air program at the Natural Resources Defense Council, a U.S. environmental group. "It's the kind of year we expect, given the global warming trend is ongoing." | <urn:uuid:3260f27b-c24b-4eac-819c-739b2370c6a1> | 2.9375 | 516 | News Article | Science & Tech. | 56.033961 | 2,154 |
What's New at the Observatory?
There are still a couple of safety issues in the dome to
clear up and the display areas of the observatory are still
being prepared, but we hope to be able to start public tours
soon after the official opening of the building May 25th.
The Transit of Venus on June 5th
The Transit of Venus
is among the rarest astronomical phenomena and won't happen
again until the year 2117! What is a "transit" and why is it so
A transit happens when a planet (in this
case Venus) comes between the Earth and the Sun, so that its disc is
outlined against the bright disc of the Sun. This happens rarely
because the orbits of Earth and Venus are not in exactly the same
plane, but each are inclined by a different amount. Careful timing
of the event has led to a precise determination of the distance
between the Sun and Earth.
Not all areas of the Earth will see the
transit on June 5th. In Corner Brook we will only witness the
beginning of the transit; the Sun will set while Venus is still
visible against the solar disc. We hope to have our new solar
telescope installed in time to have a public viewing - with a
little luck from the weather!
Check back here for more information.
is Global Astronomy Month!
professional astronomers around the world are celebrating
the sky this month. There are numerous events scheduled
world-wide, including global star parties and remote
(online) observing. Find out more from an
Astronomers Without Borders.
First Student Photos from Our Telescope!
On April 3rd the
Physics 2151 class held a poster session containing several images they took with the
new telescope. Despite the terrible weather this term, the enthusiastic students were able to be the first class
to use the telescope!
students in EaSc 2150
- The Solar System - will again have opportunities to use the
telescope, both for observing and for course projects.
FIRST LIGHT THROUGH THE TELESCOPE!!!
Saturday 29 October 2011
Saturday, 29 October saw "first
light" through the
new Grenfell Observatory 0.60 m telescope! Starlight hit the
mirror for the first time. Although cloudy, we were able to
use "holes" in the clouds for the initial testing.
and Richard Neel (off camera)
of DFM Engineering completed the check of the telescope's
polar alignment - it's OK! - and initial focusing. On hand
to assist were Grenfell's thrilled astronomers Doug Forbes (centre)
and Darlene English (right). | <urn:uuid:4dd48e9b-c822-43d2-b350-21083b39a57b> | 3.15625 | 565 | News (Org.) | Science & Tech. | 55.963195 | 2,155 |
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 March 8
Explanation: As the robot spacecraft NEAR lowers itself toward asteroid 433 Eros, more surface details are becoming visible. Last week's maneuvers brought NEAR to within 204 kilometers of the floating mountain's surface. With increased resolution, NEAR's camera then documented Eros' unusual shape, craters large and small, boulders, and mysterious grooves similar to asteroid Gaspra and Martian moon Phobos. If you could stand on Eros, you would still be too small to be visible on this recent image, which shows features as small as 20 meters across. However, you would feel gravity only 1/1000 that on Earth, so that you could easily jump over even this large 5 kilometer wide crater.
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:853c31be-8914-4b9e-ac6e-b0bd88dc5861> | 3.109375 | 226 | Knowledge Article | Science & Tech. | 48.566456 | 2,156 |
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.
2006 May 22
Explanation: What arm is 17 meters long and sometimes uses humans for fingers? The Canadarm2 aboard the International Space Station (ISS). Canadarm2 has multiple joints and is capable of maneuvering payloads as massive as 116,000 kilograms, equivalent to a fully loaded bus. Canadarm2 is operated by remote control by a human inside the space station. To help with tasks requiring a particularly high level of precision and detail, an astronaut can be anchored to an attached foot constraint. The arm is able propel itself end-over-end around the outside of the space station. Pictured above, astronaut Stephen Robinson rides Canadarm2 during the STS-114 mission of the space shuttle Discovery to the ISS in 2005 August. Space shuttles often deploy their own original version of a robotic arm dubbed Canadarm. Next year, a second robotic arm is scheduled to be deployed on the space station.
Authors & editors:
NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: EUD at NASA / GSFC
& Michigan Tech. U. | <urn:uuid:ca607d11-3a3e-4451-bd62-38451640d729> | 3.5625 | 266 | Knowledge Article | Science & Tech. | 41.975244 | 2,157 |
It’s not easy being a soil scientist at a meeting of the Convention on Biological Diversity. After all, when tigers, whales, and orchids are in danger, who cares about worms? “It would be an important step if anyone here at COP 10 noticed soil biodiversity exists,” said Luca Montanarella, SOIL Action Leader with the European Commission here to promote a brand new European Atlas of Soil Biodiversity that he edited.
No one knows exactly how many organisms live underground, but Montanarella said they probably represent at least a quarter, and probably over half, of all the species on Earth. Soil-dwelling species range from moles (one of the few vertabrates that spends its whole life underground) to ants, beetles, spiders and millipedes. The vast majority of species that live in dirt, however, are too small to see with the naked eye. This category includes fantastically bizarre creatures, like the Polyacanthus aculeatus (a spine-covered micro-armadillo), the Paracineta lauterborn (a globular protozoan which would not be out of place in a pack of Pokemon cards) and the Milnesium tardigradum (imagine a crumpled paper bag with feet).
Lest you think these underfoot critters have little relevance for your life, recall that healthy soil forms the literal base of our food supply, and soil critters are indispensable for healthy soil. Soil is also a crucial carbon sink, a sponge for rainfall that regulates water supplies, and even a source for medicines. For instance, rapamycine, a key drug used to prevent rejection of organ transplants, is produced using a microbe discovered in soil from Easter Island.
It’s impossible to say just how many soil organisms are endangered, Montanarella said, because most haven’t been tracked with the same attention given to more glamorous species. Nevertheless, agrochemicals, soil compaction from heavy farm machinery, and pavement all pose major threats to the creatures that live inside the earth.
About 25 or so people came to hear Montanarella talk today at a lunchtime event (which, for undisclosed reasons, had been relegated to a distant and secluded wing of the conference hall). Enthusiasm in the room was high, and several delegates in the audience asked what they could do to raise the political profile of dirt. For now, Montanarella said he’d be happy if policy makers just stopped ignoring. | <urn:uuid:70e8c36e-5cab-452f-a807-17b63fd5c0c9> | 3.390625 | 524 | News Article | Science & Tech. | 29.162554 | 2,158 |
The Fine Art of Waddling
Natural History, March 2001
When Tim Griffin and Rodger Kram set out to study how penguins walk, they didn’t expect to be impressed. Compared with long-legged ostriches striding across a plain, waddling penguins come up short. Underwater they may be able to race like torpedoes in tuxedos, but on land they are more apt to evoke laughter than to inspire respect.
Previous research on penguins seemed to back up the laughter with hard numbers. Pound for pound, a penguin on land uses twice as much energy as other animals of its size to walk a given distance. Scientists laid the blame for this expense on waddling, the (presumably) energetically costly business of
the bird’s throwing its body first to one side and then to the other as it walks.
Griffin and Kram, both at the University of California, Berkeley, decided to test the assumption by measuring the work involved in waddling. So they filmed emperor penguins walking over a force-sensitive plate. Their data enabled them to calculate not just the force of each step but also the direction in which the force was acting and how fast the penguins were moving.
Similar studies on humans and other land animals have shown that walking is a surprisingly efficient way to move. Planting a foot in front of your body as you walk forward, you rise up slightly. Once your body is positioned directly above the foot, you start to fall forward and downward. In this process, much of the kinetic energy of your forward movement is turned into gravitational energy, which is then transformed into moving forward again. The same process occurs when a pendulum converts the energy it derives from moving side to side into moving upward against gravity A walking person is like a pendulum turned upside down. Taking advantage of gravity this way saves lots of energy. Experiments have shown, for example, that a person’s muscles need to supply only 35 percent of the work they would have to perform if there were no inverted pendulum involved. As the walker “falls” with each step, the muscles manage to recover 65 percent of the energy they put into a stride.
Griffin and Kram were amazed to discover that in this respect the penguins were actually superior to humans, recovering up to 80 percent of the energy they put into each step among the highest rates ever recorded for any animal. How is this possible? Penguins not only rise and fall along the line in which they are walking (as we do); they also swing their bodies from side to side like pendulums. This side-to-side waddling provides additional energy for fighting gravity.
Energy from this sideways movement helps the penguin reach an upright position when only one leg is on the ground. As the bird swings back-or rather, falls-to the opposite side, it uses gravitational energy both to move sideways and to step forward.
Biologists have given waddling a bad rap, suggest Griffin and Kram. Penguins do pay a steep price to walk, but the researchers claim that waddling is not to blame. Instead, they propose, the trouble comes from having such short legs. Long-legged animals with longer strides maintain contact with the ground for more time during each step than do short-legged creatures. This allows a long-legged creature to use slower-working, more efficient muscle fibers. An emperor penguin is a hefty bird, weighing about forty pounds-in the same range as the flightless South American rhea, which is similar to an ostrich. But the emperor’s legs are only one-third the length of the rhea’s, or only about as long as those of the guinea fowl, a bird weighing only three pounds. Moving a rhea’s body around on a guinea fowl’s legs, a penguin has no choice but to use a lot of energy.
Like many animals, penguins are caught in a biomechanical bind. With their flipperlike wings, they are well adapted for swimming, and their short legs may help reduce drag underwater. But because they’re birds and not fish, penguins cannot completely give up life on land, where they find mates, lay their eggs, and raise their chicks. Emperors are, in fact, champion walkers, traversing up to 150 miles of frozen sea ice to reach their winter rookeries. Far from wasting energy, waddling may help keep a penguin alive.
Copyright 2001, Carl Zimmer. Reproduction or distribution is prohibited without permission. | <urn:uuid:f7b03d25-d0e8-4e42-aac6-3ea3b96c51ba> | 3.671875 | 955 | Knowledge Article | Science & Tech. | 49.515705 | 2,159 |
Wednesday, December 5th 2012, 12:21 PM EST
There is now growing consensus between most weather computer models that cold air from the east is likely to spread across Britain next week.
If so, it will be the first time since March that high pressure has properly dominated our weather, and will end a long sequence of at times record breaking wet weather.
And it looks to be a classic winter-time set up, with a powerful anticyclone developing across Scandinavia and into western Russia, pulling in cold easterly winds across a large part of the country, hence the old saying 'the beast from the east'.
The diagram below is what's known as an 'ensemble mean' from the ECMWF model for the middle of next week.
The computer program is run 51 times, each time with slightly different starting conditions.
The solutions are then compared, and give forecasters an indication as to how likely a particular outcome is.
Article continues below this advert:
From the midnight run of the computer, 41 out of 51 of the solutions suggest an easterly weather pattern developing next week, with varying degrees of cold.
10 solutions do not agree with this cold easterly outcome, hence there is still some uncertainty. But, there's clearly a large majority in favour of this scenario at the moment.
What is much less certain is how much snow is likely to be associated with this change in the weather.
Quite often in these situations, there's a distinct lack of precipitation apart from wintry flurries which can develop as the air picks up moisture as it heads westwards across the North Sea.
But some solutions are suggesting 'disturbances' in the easterly flow, which would bring the risk of more general snowfall.
And of course there's always the risk of milder air trying to re-assert itself from from the west, which would also bring the risk of snow.
At the moment though, the cold but relatively dry scenario is the most likely outcome.
One way or the other, our weather is likely to become more seasonal in the lead up to Christmas.
Follow me on twitter @Hudsonweather
Comments section below this advert: | <urn:uuid:7e431610-37b6-4142-b512-dbdcee23d631> | 2.734375 | 455 | Personal Blog | Science & Tech. | 49.621459 | 2,160 |
James Cameron’s descent to the Challenger Deep – we have adventure, intrigue, and a great story for the media. But we also have an amazing opportunity for SCIENCE!
Despite a faulty hydraulics hampering sample collections, the Deepsea Challenger managed to grab half a sediment core – a cupful of muddy, watery ooze from the deepest point in the ocean:
“Jim recovered about 50 millileters of muddy seawater that I gleefully processed for culturing and for genomic studies,” Doug Bartlett, chief scientist for the DEEPSEA CHALLENGE project, said in an email to National Geographic News.
“Can’t wait to see what new critters (Bacteria, Archaea, and fungi) that we discover,” said Bartlett, a marine biologist at the Scripps Institution of Oceanography in San Diego, California.
Some might lament Cameron’s technical difficulties and shake their heads at the lost sampling opportunity. But even half a sediment core will reveal precious information about one of the last frontiers on earth. We have plenty to work with.
In molecular terms, 50 milliliters is a LOT of sample. Normally my lab protocols call for 200 microliters of mud for a single extraction of environmental DNA. So with his one cup of mud, James Cameron can do 250 DNA extractions–and you only need one or two extractions (maybe a few more, which are then concentrated and pooled if there isn’t a lot of DNA because of few animals or small amounts of tissue) before you can move forward and produce gene sequences, using high-throughput platforms such as the Illumina Hi-Seq.
So even with a single drop of sample, you can obtain hundreds of millions of DNA sequences from species inhabiting the Challenger Deep. And there’s no restriction to any particular taxonomic group. The power of DNA means that we will be able to characterize deep sea life across all known domains–bacteria, archaea, eukaryotes, and even viruses.
One of the first things to sequence will be ribosomal RNA, a conserved gene that essentially serves as a molecular barcode (since every cell needs its ribosomes to survive!) and allows us to place species on branches within the Tree of Life. By comparing ribosomal genes from the Challenger Deep to those from species that have already been studied, we’ll be able to place this deep-sea community in an evolutionary context and investigate how life might have evolved in the ocean depths. What other environments contain closely related species? How divergent are the ribosomal genes in the Mariana Trench (and from this, we can start guessing how long these trench communities have been isolated–if at all–from other deep sea habitats)? Is the Challenger Deep harboring any novel, undiscovered branches on the Tree of Life?
We’ll also get an environmental metagenome from this sequencing effort — randomly sequenced pieces of DNA representing every species’ genome lurking in that muddy sample. This will give us an expanded view compared to ribosomal genes, and we can start inferring things about community function. What type of genes are prevalent in the deepest, darkest ocean trench? The types of genes we find can tell us a lot about how a community survives (does it rely on scarce food sinking from above, or have species adapted to use alternative metabolic pathways such as chemosynthesis), and how an assemblage of organisms might inherently depend on each other to survive in an extreme environment. If the community in the Challenger Deep is not too complex (a handful of species, or a good pool of abundant ones) and the scientists at Scripps decide to sequence a LOT of DNA from this precious mud (a couple runs on the Illumina Hi-Seq can get you close to a billion DNA sequences), then it is possible that we might be able to assemble whole genomes from this random sample of mud. So instead of a ribosomal gene we’ll potentially have an entire genome as a molecular barcode for some microbial species–and for inferring how evolution happened in the deep-sea, a genome will give you a lot more information than just a short ribosomal sequence.
In addition to extracting DNA we can also take out the RNA and look at patterns in molecules such as mRNA (expressed transcripts of genes, if you remember back to high school biology). So in addition to finding out who’s there and what their genomes say they can do, RNA can tell us what these species might actually be doing. Remember that there’s a lot of “junk” DNA sitting around in any given genome (and you’ll get a lot of this information from a random environmental metagenome sequencing), so its always good to have additional information about what type of genes are being expressed. Now the pressure and temperature changes will have sent most species’ cellular machinery into overdrive during Cameron’s ascent to the surface, and we may get more of a “help, help , I’m dying” reaction from the community. Its always tricky to interpret gene expression. But in many ways, any data is good data. Gene expression from the Challenger Deep may tell us some very exciting things.
Doug Bartlett from Scripps also indicated plans to try and culture some microorganisms from Cameron’s sample — while there’s no guarantee of success (the pressure change and inherent difficulty in culturing microbes both present significant hurdles), any cultured species would be closely scrutinized and provide mountains of data for years to come. Not only could we sequence genomes from cultured species, but we could organize sophisticated experiments to figure out exactly what nutrients they need, their metabolic pathways, and novel compounds produced that all contribute to adaptation in the deep sea. We may soon have alien life growing in a Southern California lab!
These approaches alone will give you an unprecedented view into life in the Mariana Trench. But we can still do more with that half core.
Cameron noted that the ocean floor he saw was lunar-like, smooth and featureless–but that doesn’t mean the environment is exclusively the realm of microbes. In fact, we know that bigger (albeit still microscopic) species like foraminifera do live in the Challenger Deep (Todo et al., Science, 2005), and Cameron saw amphipods swimming around before the sample had even been returned to the lab. Which means we can probably get some cool visuals if we take another drop of mud and peer at its contents under the microscope. If there are amphipods and forams, there will be nematodes in Cameron’s sample. If nematodes can live ~3km deep within the fracture water of South African mines, they can certainly put up with a little bit of pressure and scraps of food in the Hadal zone. So yeah, we should be able to get some pictures like this (for inspiration and general awesomeness):
I’m not done yet. We can still get more from that core, including:
- Characterizing the chemical makeup of the sediment. This can be done via methods such as stable isotope analysis, and we can ask questions such as: Can we pinpoint the original source of the organic matter in the Challenger Deep? What type of food is available for organisms down there? What does that say about conditions and species’ habitats in the deepest ocean trenches?
- Sediment geochemistry. What type of sediment is down there? Where did it come from (what continent or ocean region) and what trajectory might it have taken as it slowly sunk to the deepest depths?
All in all, Cameron’s sample will fundamentally contribute to our knowledge about some big questions in biology, such as:
Biological adaptations to life in extreme environments
Tim Shank, a deep-sea biologist at the Woods Hole Oceanographic Institution in Massachusetts, says that the waters above Challenger Deep are extremely unproductive; there is little algal life at the surface, and, therefore, less food is cycled down to deeper waters. “If it had been a trench with a productive water column, like the Kermadec Trench near New Zealand, I think he would have seen much more biology,” says Shank. However, sediment samples are certain to contain billions of microbes.
Insight into what life might be like on other planets:
The mud could contain exotic species of microbial life that may not only advance our understanding of the deep ocean but also help in the search for extraterrestrial life. For instance, scientists think Jupiter’s moon Europa could harbor a global ocean beneath its thick shell of ice—an ocean that, like Challenger Deep, would be lightless, near freezing, and home to areas of intense pressure. (See “Could Jupiter Moon Harbor Fish-Size Life?”)
So for those of you that scoffed at the botched sampling, there’s some serious scientific amazingness that awaits us in that half core of mud. | <urn:uuid:c27ab378-b23c-42df-9c5a-4aedecc4a586> | 3.546875 | 1,872 | Personal Blog | Science & Tech. | 36.186005 | 2,161 |
Research at the Intersection of the Physical and Life Sciences (2009)Board on Life Sciences
Each report is produced by a committee of experts selected by the Academy to address a particular statement of task and is subject to a rigorous, independent peer review; while the reports represent views of the committee, they also are endorsed by the Academy. Learn more on our expert consensus reports.
An increasing number of scientists are addressing problems that lie at the intersection of the life sciences and the physical sciences. This report discusses how some of the most important scientific and societal challenges can be addressed, at least in part, by collaborative research among traditional disciplines, including biology, chemistry, and physics. It describes how tools and techniques developed in the physical sciences are being applied to current biological mysteries and identifies five areas of potentially transformative research. Combining the skills and knowledge of researchers in life sciences and physical sciences to identify structures and processes that form the basis for living systems represents one such opportunity. Scientists could potentially use that insight to construct systems with some characteristics of life. Such systems could, for example, synthesize materials or carry out functions not yet seen in natural biology. The report recommends several ways to accelerate such cross-discipline research.
- Most often, collaborative research among the physical and life sciences applies concepts, analyses, and tools developed in the physical sciences to problems in the biological sciences.
- One area producing effective cross-discipline research opportunities centers on the dynamics of systems. Equilibrium, multistability, and stochastic behavior--concepts familiar to physicists and chemists--are now being used to tackle issues associated with living systems such as adaptation, feedback, and emergent behavior.
- Technologies, from the physical sciences, for recognizing symptoms and identifying pathogen strains allow early detection and intervention against natural -- and man-made -- biological threats. Using techniques related to speech recognition, mathematicians have worked to map the genetic similarity of influenza viruses. Using color and spatial distribution, subtle evolved differences in virus strains can be identified, and decisions about the potential effectiveness of vaccines become easier.
- The potential benefits for society from research that integrates the physical and biological sciences are profound -- in medicine, agriculture, energy, and climate science.
- The scientific and societal challenge of understanding the role of physical/biological interactions in climate change is at least as profound in the area of solutions as it is in impacts. Essentially all possible approaches for offsetting emissions of greenhouse gases, including biological sequestration, decreased deforestation, and geological and deep ocean sequestration, involve changes to biological systems.
- There is no reason, in principle, why self-reproducing, evolving systems cannot be generated in a wide range of chemical formats. Using the knowledge from the physical sciences, we face the ambitious possibility of generating synthetic units with basic attributes of living matter such as compartmentalization, metabolism, homeostasis, replication, and the capacity for Darwinian evolution. Such self-replicating, evolving organisms have the potential to create more efficient functions for a broad range of applications. | <urn:uuid:608a1744-c85e-4e97-a18b-c9bc480d6365> | 2.859375 | 615 | Academic Writing | Science & Tech. | 5.418363 | 2,162 |
Distillation Column Using the Francis Formula for Flow through Weirs
Consider a distillation column operating at atmospheric pressure with 10 stages, a partial reboiler, and a total condenser. An equimolar mixture composed of ethanol and water is to be separated by this distillation column. The feed is a saturated liquid with a flow rate equal to 10 kmol/min. Feed enters at stage 8, counting from the top. At normal operating conditions, the reflux and reboil ratios are set equal to 10 and 15, respectively. If you assume (1) a uniform tray spacing equal to 24 in and (2) an operating vapor-phase velocity equal to 80% of the value of the flooding velocity, then the column diameter can be calculated and is equal to 3.394 m. The active area is set equal to (i.e. a fraction of the total cross-sectional area of the column).
The momentum balance for each tray is neglected. The Francis weir formula is assumed and provides the additional equations used in the Demonstration in order to compute molar holdup of the trays. The weir height is set equal to 5 cm. In addition, condenser and reboiler volumes are taken equal to .
A step in either the reflux or reboil ratio is applied at . For every stage, plots of the composition and the temperature profiles as well as the molar holdup (all variables are versus time in minutes) for user-set values of the percent step are displayed by the Demonstration. The most drastic dynamic effects are observed in the lower part of the column, from the feed stage downwards.
The Francis formula for flow through weirs is given by:
where is the molar holdup at stage in kmols, is the weir height in m, is the molar flow rate in kmol/min, is the gravitational acceleration, is the active area, is the weir length (calculated from the knowledge of the active area and from pure geometrical considerations), and is the liquid density at stage .
Expressions for pure component molar liquid densities and vapor and liquid enthalpies were adapted from Aspen HYSYS.
The mixture is assumed to obey modified Raoult's law, and activity coefficients are predicted using the Wilson model .
G. M. Wilson, "Vapor-Liquid Equilibrium XI: A New Expression for the Excess Free Energy of Mixing," Journal of the American Chemical Society, 86(2), 1964 pp. 127–130. | <urn:uuid:7d1df1b1-73d9-4334-b3d6-6a6628e10797> | 3.359375 | 522 | Documentation | Science & Tech. | 49.187274 | 2,163 |
Broaden your selection:
- 4tH is a Forth compiler with a little difference. Instead of the standard Forth engine it features a conventional compiler. 4tH is a very small compiler that can create bytecode, C-embeddable bytecode, standalone executables, but also works fine as a scripting language. It supports about 95% of the ANS Forth CORE wordset and features conditional compilation, pipes, files, assertions, forward declarations, enumerations, structures, suspended execution, recursion, include files, etc. It comes with an RPN calculator, line editor, preprocessor, compiler, decompiler, C-source generator, a virtual machine, and a multitasking environment.
- A Bingo
- Rails A/B testing. One minute to install. One line to set up a new A/B test. One line to track conversion.
- A+ is a powerful and efficient programming language. It has a rich set of functions and operators, a modern GUI with many widgets and automatic synchronization of widgets and variables, asynchronous execution of functions associated with variables and events, dynamic loading of user compiled subroutines, and many other features. Execution is by a rather efficient interpreter. It is mainly used in a computationally-intensive business environment, but many critical applications written in A+ have withstood the demands of real world developers over many years. It is written in an interpreted language, so applications tend to be portable.
- ACDK is a development framework with a similar target of Microsoft's .NET or Sun's ONE platform, but instead of using Basic/C# or Java as programming language, it bases C++ as core implementation language. ACDK implements the standard library packages, including acdk::lang, acdk::lang::reflect, acdk::util, acdk::io, acdk::text (including regexpr), acdk::net, acdk::sql, acdk::xml and more, as well as technologies like flexible Allocator/Garbage Collection, Threading and Unicode. With the extensions of ACDK C++ objects are available for reflection, serialization, aspect oriented class attributes and [D]ynamic [M]ethod [I]nvocation. This DMI act as an universal object oriented call interface to connect C++ with scripting languages (Java, Perl, Tcl, Python, Lisp, Visual Basic, VBScript) and standard component technologies (CORBA, COM+).
- ACL2 is a mathematical logic and a mechanical theorem prover to help you reason in the logic (which is a subset of applicative Common Lisp). The theorem prover is an ``industrial strength version of the Boyer-Moore theorem prover, Nqthm. Users can build models of all kinds of computing systems in ACL2, just as in Nqthm, even though the formal logic is Lisp. Once you've built an ACL2 model of a system, you can run it and use ACL2 to prove theorems about the model.
- ADG: Automatic Drawing Generation
- The ADG library (Automatic Drawing Generation) is a set of functions focused on automating the drawing of mechanical parts. It is not a CAD system but a library providing a non-interactive canvas where you can put common CAD entities such as paths, xatches and quotes, to create your technical drawings. The final result can be displayed inside a GTK+ widget or exported to any cairo available format, such as PostScript and PDF documents or PNG and SVG images.
- AGFL is a parser generator for natural languages. It can cope with ambiguity, which is a must for natural languages, has a lexicon system and is quite fast. If you don't know what to think of it, think "yacc" (or "bison") without shift-reduce conflicts.
- AKFAvatar is a fancy graphical user interface for applications, where an avatar appears on the screen and tells things to the user via a speech bubble. There can also be recorded audio files, so that the user even can hear what it is saying.
With AKFAvatar you can easily write cross platform applications in Lua. Lua scripts don't even need to be compiled for the target platform. It has an interface for C programs, which can also be used for Objective-C or C++. Furthermore there are bindings for Free Pascal and GNU-Pascal.
- 'aRts' is a framework for developing modular multimedia applications. The sound server, artsd, lets multiple applications cooperatively process and output sound and music. aRts provides its filter and synthesis capabilities to other applications using the multimedia communication protocol (MCOP). The package is also capable of modular realtime synthesis. It can create sounds & music (realtime midi synthesis) using small modules like oscillators for creating waveforms, various filters, mixers, faders, etc. As of Dec 02, 2004, development on this project has been discontinued.
- A Virtual File System lets programs look inside archived or compressed files, or access remote files without recompiling the programs or changing the kernel. It currently supports floppies, tar and gzip files, zip, bzip2, ar and rar files, ftp sessions, http, webdav, rsh/rcp, ssh/scp. Quite a few other handlers are implemented with the Midnight Commander's external FS.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the page “GNU Free Documentation License”.
The copyright and license notices on this page only apply to the text on this page. Any software described in this text has its own copyright notice and license, which can usually be found in the distribution itself. | <urn:uuid:b1556d22-776f-404a-9eaf-b9ca17840615> | 2.734375 | 1,241 | Content Listing | Software Dev. | 39.178174 | 2,164 |
To print a list of all the occurrences of a specified symbol, use whereis symbol, where symbol can be any user-defined identifier. For example:
(dbx) whereis table forward: `Blocks`block_draw.cc`table function: `Blocks`block.cc`table::table(char*, int, int, const point&) class: `Blocks`block.cc`table class: `Blocks`main.cc`table variable: `libc.so.1`hsearch.c`table
The output includes the name of the loadable objects where the program defines symbol, as well as the kind of entity each object is: class, function, or variable.
Because information from the dbx symbol table is read in as it is needed, the whereis command registers only occurrences of a symbol that are already loaded. As a debugging session gets longer, the list of occurrences can grow (see Debugging Information in Object Files and Executables).
For more information, see whereis Command. | <urn:uuid:1a6e4c3c-49c3-4032-83f7-751ef29dfff7> | 3.015625 | 213 | Documentation | Software Dev. | 57.795998 | 2,165 |
This module provides low-level primitives for working with multiple threads (also called light-weight processes or tasks) — multiple threads of control sharing their global data space. For synchronization, simple locks (also called mutexes or binary semaphores) are provided. The threading module provides an easier to use and higher-level threading API built on top of this module.
The module is optional. It is supported on Windows, Linux, SGI IRIX, Solaris 2.x, as well as on systems that have a POSIX thread (a.k.a. “pthread”) implementation. For systems lacking the _thread module, the _dummy_thread module is available. It duplicates this module’s interface and can be used as a drop-in replacement.
It defines the following constants and functions:
Raised on thread-specific errors.
Changed in version 3.3: This is now a synonym of the built-in RuntimeError.
This is the type of lock objects.
Start a new thread and return its identifier. The thread executes the function function with the argument list args (which must be a tuple). The optional kwargs argument specifies a dictionary of keyword arguments. When the function returns, the thread silently exits. When the function terminates with an unhandled exception, a stack trace is printed and then the thread exits (but other threads continue to run).
Raise a KeyboardInterrupt exception in the main thread. A subthread can use this function to interrupt the main thread.
Raise the SystemExit exception. When not caught, this will cause the thread to exit silently.
Return a new lock object. Methods of locks are described below. The lock is initially unlocked.
Return the ‘thread identifier’ of the current thread. This is a nonzero integer. Its value has no direct meaning; it is intended as a magic cookie to be used e.g. to index a dictionary of thread-specific data. Thread identifiers may be recycled when a thread exits and another thread is created.
Return the thread stack size used when creating new threads. The optional size argument specifies the stack size to be used for subsequently created threads, and must be 0 (use platform or configured default) or a positive integer value of at least 32,768 (32 KiB). If changing the thread stack size is unsupported, a RuntimeError is raised. If the specified stack size is invalid, a ValueError is raised and the stack size is unmodified. 32 KiB is currently the minimum supported stack size value to guarantee sufficient stack space for the interpreter itself. Note that some platforms may have particular restrictions on values for the stack size, such as requiring a minimum stack size > 32 KiB or requiring allocation in multiples of the system memory page size - platform documentation should be referred to for more information (4 KiB pages are common; using multiples of 4096 for the stack size is the suggested approach in the absence of more specific information). Availability: Windows, systems with POSIX threads.
The maximum value allowed for the timeout parameter of Lock.acquire(). Specifying a timeout greater than this value will raise an OverflowError.
New in version 3.2.
Lock objects have the following methods:
Without any optional argument, this method acquires the lock unconditionally, if necessary waiting until it is released by another thread (only one thread at a time can acquire a lock — that’s their reason for existence).
If the integer waitflag argument is present, the action depends on its value: if it is zero, the lock is only acquired if it can be acquired immediately without waiting, while if it is nonzero, the lock is acquired unconditionally as above.
If the floating-point timeout argument is present and positive, it specifies the maximum wait time in seconds before returning. A negative timeout argument specifies an unbounded wait. You cannot specify a timeout if waitflag is zero.
The return value is True if the lock is acquired successfully, False if not.
Changed in version 3.2: The timeout parameter is new.
Changed in version 3.2: Lock acquires can now be interrupted by signals on POSIX.
Releases the lock. The lock must have been acquired earlier, but not necessarily by the same thread.
Return the status of the lock: True if it has been acquired by some thread, False if not.
In addition to these methods, lock objects can also be used via the with statement, e.g.:
import _thread a_lock = _thread.allocate_lock() with a_lock: print("a_lock is locked while this executes") | <urn:uuid:149aa958-fe47-40a1-b4b9-4eaea0d3f725> | 2.53125 | 969 | Documentation | Software Dev. | 50.395955 | 2,166 |
The current cycle of global warming is changing the rhythms of climate that all living things have come to rely upon. What will we do to slow this warming? How will we cope with the changes we've already set into motion? While we struggle to figure it all out, the face of the Earth as we know it—coasts, forests, farms, and snowcapped mountains—hangs in the balance.
More About Global Warming
See National Geographic's full coverage of the 2010 Gulf of Mexico oil spill: pictures, news reports, and first-person accounts.
Burning fossil fuels, humans pump CO2 into the atmosphere. Fortunately, plants and ocean waters gather it in. But what if this great recycling system went awry?
See the effects global warming has had on Antarctic glaciers and the wildlife that depends on them.
Learn more about these underground reservoirs of steam and hot water that can be tapped to generate electricity or to heat and cool buildings directly.
@NatGeoGreen on Twitter
The Great Energy Challenge
An initiative to help you understand our current energy situation.
See how you measure up against others, and how changes at home could do tons to protect the planet.
Special Ad Section
The World's Water
NG's new Change the Course campaign launches. When individuals pledge to use less water in their own lives, our partners carry out restoration work in the Colorado River Basin.
A special series on how grabbing water from poor people and future generations threatens global food security, environmental sustainability, and local cultures. | <urn:uuid:58a5802e-df03-455e-a035-890db1abafc1> | 3.265625 | 313 | Content Listing | Science & Tech. | 50.200309 | 2,167 |
The Arctic atmospheric boundary layer (AABL) in the central Arctic was characterized by dropsonde, lidar, ice thickness and airborne in situ measurements during the international Polar Airborne Measurements and Arctic Regional Climate Model Simulation Project (PAMARCMiP) in April 2009. We discuss AABL observations in the lowermost 500 m above (A) open water, (B) sea ice with many open/refrozen leads (C) sea ice with few leads, and (D) closed sea ice with a front modifying the AABL. Above water, the AABL had near-neutral stratification and contained a high water vapor concentration. Above sea ice, a low AABL top, low near-surface temperatures, strong surface-based temperature inversions and an increase of moisture with altitude were observed. AABL properties and particle concentrations were modified by a frontal system, allowing vertical mixing with the free atmosphere. Above areas with many leads, the potential temperature decreased with height in the lowest 50 m and was nearly constant above, up to an altitude of 100–200 m, indicating vertical mixing. The increase of the backscatter coefficient towards the surface was high. Above sea ice with few refrozen leads, the stably stratified boundary layer extended up to 200–300 m altitude. It was characterized by low specific humidity and a smaller increase of the backscatter coefficient towards the surface.
AWI Organizations > Climate Sciences > Polar Meteorology
AWI Organizations > Climate Sciences > Sea Ice Physics | <urn:uuid:a332b404-2d33-4769-bf90-9aaa9b3a74f0> | 2.84375 | 308 | Academic Writing | Science & Tech. | 19.342719 | 2,168 |
The World Climate Research Programme (WCRP) International Programme for Antarctic Buoys (IPAB), through participating research organizations in various countries, maintains a network of drifting buoys in the Antarctic sea ice zone to support a better understanding of sea ice motion, meteorology, and oceanography. The IPAB Antarctic Drifting Buoy Data archive, presently spanning the years 1995 to ... 1998, includes measurements of buoy position, atmospheric pressure, air temperature, and sea surface temperature. Data are organized by daily and three-hour averages and the raw, instantaneous, non-interpolated data values. Data were collected from buoys initially deployed in three study regions: East Antarctica; the Weddell Sea; and the Bellingshausen, Amundsen, and Ross Seas. Data are in ASCII text format and are available by ftp. Data updates will become available as data are processed and new buoys are deployed. | <urn:uuid:ad2024c4-3391-4c5f-925e-b747b0e7e4ba> | 2.96875 | 185 | Content Listing | Science & Tech. | 23.036667 | 2,169 |
NASA claims that new mysterious spheres discovered by the Mars Opportunity rover are puzzling researchers to no end. According to Opportunity's principal investigator, Steve Squyres of Cornell University in Ithaca, "this is one of the most extraordinary pictures from the whole mission."
Soon after Opportunity landed, it discovered similar spheres. The scientists nicknamed them blueberries and soon they discovered that they were rich on hematite. Those were evidence of a Mars' past full of water. But these spheres—which are 3 millimeters in diameter—are nothing like that.
Found in the Kirkwood outcrop, in the western rim of Endeavour Crater, these spherules' composition is completely different from the old Martian blueberries. Scientists still don't know how they got there and what they are supposed to be, says Squyres:
They are different in concentration. They are different in structure. They are different in composition. They are different in distribution. So, we have a wonderful geological puzzle in front of us. We have multiple working hypotheses, and we have no favorite hypothesis at this time. It's going to take a while to work this out, so the thing to do now is keep an open mind and let the rocks do the talking.
In the image you can also see spheres that have been eroded, showing a concentric internal structure. Researchers are now conducting more tests, trying to come up with an explanation on what these may be and how they got there.
But perhaps they already got the answer in Squyres' own words: "they seem to be crunchy on the outside, and softer in the middle." Obviously, Martians knew how to make chocolate Krispies cakes. [NASA] | <urn:uuid:f036ea41-18f5-4fe0-b257-5fe55f23fbef> | 3.1875 | 350 | News Article | Science & Tech. | 44.478313 | 2,170 |
Asteroids provide unique insights into the origin and early history of the solar system. Since asteroids are considered to be fairly pristine, studying them provides opportunities to learn more about the primordial solar system, its materials, processes and history. Since the discovery in 1801 of the first asteroid, Ceres, during the era when everyone was searching for the "missing planet", astronomers have been trying to understand what they are, where they came from, why they exist and what they can tell us about how our solar system formed and evolved.
Within the asteroid population are a number of sub-populations, the primary division is due to the locations of the asteroids. There are the Main Belt Asteroid (MBA) population that resides between the orbits of Mars and Jupiter (1.8–3.5 AU) and the Near-Earth Asteroid (NEA) population whose orbits have an aphelion ≤ 1.3 AU. Within both the MBA and NEA populations are further subdivisions (taxonomic classes) based on physical properties of the asteroids such as albedo, spectral curve and probable composition. There have been a number of taxonomic classification schemes, the most current iteration splits the asteroids into three complexes (C, S, and X) that combined are comprised of twenty-six distinct taxonomic classes.
Since the lifetimes of the NEAs are short (106–10 7 yrs), it is thought that the NEA population is and continues to be populated by the MBA population through various mechanisms like resonances and thermal forces. We have conducted a statistical comparison of the two populations as a whole, by complexes and individual taxonomic classes and found significant differences as well as similarities. On the surface, it appears that the NEA population is not representative of the MBA population. There are voids and relatively small numbers in taxonomic classes that exist in the NEA when compared to the MBA population and there are some important similarities. There are, however, biases that this analysis does not address that may explain our findings.
The asteroid taxonomy classification schemas are based on visible wavelength spectra. There are ∼2500 classified asteroids of which only a very small percentage have spectra in the infrared wavelength ranges. Here we demonstrate, using asteroid 1989 ML, the need for more asteroid spectra in the near-infrared wavelength range which contains much compositional information. We show that in the visible wavelengths spectra of several meteorites of very different types match the spectrum of 1989 ML.
Finally, we examine twenty-seven S and possible S Complex asteroid spectra. We find that most contain pyroxenes in the monoclinic form (clinopyroxene). Clinopyroxenes can contain calcium; however, there are some that do not. The cases of Ca-free clinopyroxenes are rare on Earth, but are readily found in the type 3 unequilibrated ordinary chondrites. Analyses of the asteroids and ordinary chondrites were conducted using the Modified Gaussian Model (MGM) and the Band Area Ratio. We also examined two terrestrial Ca-free clinopyroxenes using the MGM. From our results we conclude that the surfaces of S Complex asteroids are consistent with the type 3 unequilibrated ordinary chondrites. | <urn:uuid:005e2ddf-7192-4800-8e1e-eb44684810f9> | 3.90625 | 663 | Academic Writing | Science & Tech. | 28.387542 | 2,171 |
Ever wonder what it's like on other planets? On this Moment of Science, find out what it's like on Mercury.
Do other animals besides humans cry? Find out on this Moment of Science.
What do 6 month olds do better than 9 month olds? Find out on this Moment of Science.
Recent studies suggest a correlation between progesterone levels and paternal behavior. Learn more on this Moment of Science.
You probably already know that humans are warm-blooded, while creatures like snakes are cold-blooded. Scientists prefer the terms endothermic and ectothermic. Snakes are ectothermic–they’re dependent on their environment for heat.
There are few insects more reviled than the cockroach. Maybe we’re just jealous: cockroaches were around long before humans, and will continue to do their thing long after our species has gone the way of the woolly mammoth. | <urn:uuid:d075681d-fdc7-4d9f-9c7c-1e15dabd4c43> | 2.9375 | 187 | Content Listing | Science & Tech. | 57.529423 | 2,172 |
Inheritance diagram for IPython.history:
History related magics and functionality
Alternate name for %history.
Print input history (_i<n> variables), with most recent last.
%history -> print at most 40 inputs (some may be multi-line)%history n -> print at most n inputs%history n1 n2 -> print inputs between n1 and n2 (n2 not included)
Each input’s number <n> is shown, and is accessible as the automatically generated variable _i<n>. Multi-line statements are printed starting at a new line for easy copy/paste.
-n: do NOT print line numbers. This is useful if you want to get a printout of many lines which can be directly pasted into a text editor.
This feature is only available if numbered prompts are in use.
-t: (default) print the ‘translated’ history, as IPython understands it. IPython filters your input and converts it all into valid Python source before executing it (things like magics or aliases are turned into function calls, for example). With this option, you’ll see the native history instead of the user-entered version: ‘%cd /’ will be seen as ‘_ip.magic(“%cd /”)’ instead of ‘%cd /’.
-r: print the ‘raw’ history, i.e. the actual commands you typed.
-g: treat the arg as a pattern to grep for in (full) history. This includes the “shadow history” (almost all commands ever written). Use ‘%hist -g’ to show full shadow history (may be very long). In shadow history, every index nuwber starts with 0.
- -f FILENAME: instead of printing the output to the screen, redirect it to
- the given file. The file is always overwritten, though IPython asks for confirmation first if it already exists.
Repeat a command, or get command to input line for editing
Place a string version of last computation result (stored in the special ‘_’ variable) to the next input prompt. Allows you to create elaborate command lines without using copy-paste:
$ l = ["hei", "vaan"] $ "".join(l) ==> heivaan $ %rep $ heivaan_ <== cursor blinking
Place history line 45 to next input prompt. Use %hist to find out the number.
%rep 1-4 6-7 3
Repeat the specified lines immediately. Input slice syntax is the same as in %macro and %save.
Place the most recent line that has the substring “foo” to next input. (e.g. ‘svn ci -m foobar’). | <urn:uuid:e0e5584a-601c-4151-adac-02b20a241bc8> | 3.28125 | 607 | Documentation | Software Dev. | 61.576071 | 2,173 |
We’ve all heard of shell programming, but in the end what we write are simple scripts composed of strung-together commands, performing simple operations in a more-or-less linear manner. But the shell can do much more than what we tend to ask of it.
bash is, in my opinion, the most powerful shell on the market that doesn’t require you to be a programmer to use it. On the other hand, for those who want to learn to program it, rather than just script it, its sound principles and powerful features offer a wealth of opportunity for writing fast, flexible programs that can often out-perform most other interpreted languages.
This is a very informal crash tutorial in intermediate features of shell programming. It assumes a basic grasp of programming principles and of simple, beginner-level shell scripting. | <urn:uuid:0150470f-60c3-421b-af9b-378159591e04> | 2.65625 | 170 | Personal Blog | Software Dev. | 49.955587 | 2,174 |
The Theory of Relativity is quite possibly the greatest modern scientific discovery of all time and yet I would venture to guess that most of us have no concept of it or at the very least fail to see how everyday life is absorbed in the major concepts of the theory. We all know it:
But what does that equation really say? It’s simply saying that the mass of a body is a measure of its energy constant, where ‘E’ stands for Energy, ‘m’ stands for Mass, and ‘c2’ represents the speed of light squared. This equation is often in physics referred to as the mass-energy equivalence concept. We wont get into the math behind it, and lets face it, most of us can’t (myself included).
Einstein’s Theory of Relativity consists of two separate theories called special and general relativity. Special relativity is an expansion on Galilean relativity, which expresses how matter moves through time and space. General relativity is an expansion to his own special relativity theory, which essentially adds gravity into the mix.
So many people ask, ‘How is this a factor in my everyday life?’ We’ll let’s take a look at some things that you deal with constantly (and some I hope we never have to deal with) that are directly related to these theories.
So time travel is pretty sweet and one day maybe we can travel forward, far in time, and experience the future. Impossible? Well, the thing is… we already have at a smaller scale. You’re doing it right now in relation to anyone that is at a lower elevation than you on Earth, though it’s a small enough measure that you and I would never be able to tell without extremely sensitive equipment. Basically what time dilation describes is that the stronger the force of gravity the slower time moves for you in relation to someone who is experiencing weaker gravity. That being said, time for you wont seem to be moving slower relative to you, just as time for the other person experiencing weaker gravity wont seem to move any faster. Now only is this mathematically proven, but we have recorded the effect in real life and it is essential to one piece of equipment we all use daily now.
GPS is a staple technology found in almost all phones and every car. We use it to help us get to places we are unfamiliar with, however if GPS satellites didn’t account for time dilation, we would never get where we needed to go. Imagine the Earth with a GPS satellite coasting in motion far in orbit around Earth. The pull of Earth’s gravity (which is quite weak in relation to other objects in space) is weaker for the satellite where as your car on Earth is closer to the Earth’s mass and thus the pull of gravity is stronger. GPS works by essentially firing a radio wave from your phone to a set of satellites that triangulate your position. Easy enough, I suppose.
This is where it gets interesting and where atomic clocks located on the satellites must be exact. Your phone sends requested signals to satellites located above you in orbit, and because they are constantly moving some may be further away from you than others. If a satellite were to be directly above you then the distance the radio waves need to travel is shorter than a satellite that is located north east of you. These radio waves travel at the speed of light (which is about 670,616,629 mph. Not bad.) However, even at this speed, the satellite directly above you has less distance to travel than the one north east of you. Once the distances of at least four of the twenty-four GPS satellites in orbit are estimated by your phone in can then pinpoint your location in three dimensions.
Now time dilation has to be accounted for because the satellites are experiencing time faster than you due to your stronger gravity, so atomic clocks are programmed to account for this small difference and therefore your location will be accurate to around 10 meters or so based on your ability to broadcast and receive signals. This is why GPS tends to have a harder time in wooded areas. If your phone cannot get an accurate idea of how far the satellite is away from you because the atomic clock on board doesn’t account for time dilation (or because your signal is being obstructed), your phone would be completely inaccurate in its guess of your position on a map. Our ability to account for time dilation is precisely why your GPS gets you (most of the time) where you need to go.
Looking Back in Time:
The speed of light is constant. The reason this is so has to do with the fact that mathematically the more mass an object has the more energy it needs to reach faster and faster speeds (remember the mass-energy equivalence?). So an object with mass would need an infinite amount of energy to reach the speed of light. That being said, the smallest mass-less light, energy, or information particles are also limited to this speed. Because light is limited to this speed as well, we know a few things.
Walk outside and look quickly at the sun (don’t stare!). The image burned onto your eyes is what the sun looked like 8 minutes ago. This is because the light that is traveling from the Sun to the Earth is traveling at the speed of light, which even at that great speed takes about eight minutes to reach us. Now do the same thing later in the evening with the moon (feel free to stare all you want). The image you are seeing in the sky is about 1.26 seconds behind. It only takes 1.26 seconds for light to travel the distance between the Earth and Moon. So imagine that the sun exploded. Even after it happened, it wouldn’t be until 8 minutes later that we saw the effects in our sky. The moon would be much quicker but still delayed that 1.26 seconds.
The speed of light expressed in Einstein’s theory allows us to measure great distances in space and so a general rule of thumb is that the further you look into space the older the image you see in the sky really is. So another example is the Helix Nebula (commonly referred to as the “eye of God”), whose image in our skies is about 700 years old. This again means that it takes light 700 Earth years to cover the distance from the nebula to Earth. To see it from Earth is to look back in time 700 years. The furthest galaxies (in our observable Universe) that we can see with our current technology show that they are a distance of about 13.3 billion light years, meaning that the earliest light first generated by that galaxy has been traveling almost the entire life span of the Universe as we know it to be at an age of about 13.7 billion years old. We are literally traveling back in time just by looking in the sky, because not even light photons can travel faster than the speed of light.
Given that light travels at a maximum speed of about 670,616,629 mph, there is a greater beast that even light cannot escape. One of the interesting things about Einstein’s theory was that the math involved ended up predicting an anomaly that was quite perplexing in what it said and meant. Even Einstein thought that despite the prediction his math made, that it more than likely would not actually exist in the cosmos. The math simply predicted that extremely compact mass would deform space-time to form what they labeled as a black hole.
The best way to imagine a black hole is to pretend that you’re floating in a rowboat in an endless body of water. We’ve all seen waterfalls and we all know that the human body has limitations, because we can only row so fast. This limitation would be the speed of light in relation to a black hole. So we paddle towards what looks like a giant whirlpool waterfall where all the water is rushing towards and falling down into. We can paddle fairly well as long as we stay far away from the event horizon. This is the point at which the force of gravity is pulling stronger than the speed at which we can row. Since nothing can travel beyond the speed of light, we cannot simply row our way out of our impending doom. Gravity is stronger and will continue to become even stronger as we fall further and further in.
What this shows is that since light has a maximum speed, even light itself cannot escape the stronger pull of gravity beyond the event horizon. Any light that crosses the event horizon of a black hole cannot escape, hence the name, black hole. The pull of gravity is so strong in fact that it distorts light around the black hole, giving the outside viewer a kind of “lensing” effect around the black hole. Light bends and distorts around the black hole. Till this day we have not physically seen a black hole in the way in which we imagine them, though we are close. Lensing is one way to know a black hole is possibly near by (possibly, because other things in space also cause this), but we have, however, seen objects that are orbiting around a black hole and how they interact and thus can identify them as well.
Our own Milky Way was discovered to contain a super-massive black hole at its center by observing star orbits over a period of 15 years. It was observed that a cluster of stars were traveling in elliptical orbits around an unidentified object at speeds that would require the sort of gravity known only to a black hole. It is now believed that black holes are a prominent feature of most, if not all, galaxies.
Many consider the Theory of Relativity one of the greatest human discoveries, and because it has been rigorously tested and proven to be accurate time and time again in both mathematical and observable experimentation, it has withstood the test of time. It not only explains our Universe and makes sense of our surroundings, but also helps to push us further in understanding even more of the unknown. It makes our everyday lives easier and explains with other collected evidence how much of our Universe operates. Scientists are still looking for the link (via string theory) as to how the theory of relativity connects back to the microscopic actions of gravity, or how to explain the physics of the very small and the very big. Maybe one day Ill try and tackle some of the more easy to understand concepts of string theory or even m-theory, but they are a whole new can of worms that require patience. One day… | <urn:uuid:edc2b192-c1b9-4948-8df8-0fb735bc11e5> | 3.015625 | 2,153 | Personal Blog | Science & Tech. | 54.001435 | 2,175 |
tjreedy at udel.edu
Fri Feb 6 19:42:50 CET 2004
<mathias.foehr at mails.lu> wrote in message
news:184.108.40.206.0.20040206074906.02624b30 at www.mails.lu...
>I want to define new operators because mathematicians use special
> (eg circle plus (+), circle times (*), arrows ->) since centuries.
> It increases readability in this area and people have got used to it.
I am sympathetic to the desire and for the same reason, but there are
practical problems with operator extensibility, which is why most computer
languages lack it.
* Reuse existing operators (which Python does allow).
* Use overt functions and function calls. Operators are covert functions
with an alternate and somewhat ambiguous syntax for function calls, which
is why associativity and precedence rules are needed to disambiguate.
Short names are not all that bad, and meaningful short name also have
* Write custom additions to some version of the interpreter.
* Write a preprocessor that does a partial parse to identify custom
operators and the blocks governed by each and then use rules to rewrite
code with overt function calls. If the preprocessor is an external
program, it can be written in any language. One can preprocess 'in line',
by quoting the code, manipulating it, and then compile or execute. This
works best when the custom manipulation is pretty localized.
* Use another language
> By the way, are there hooks in python to preprocess a statement before
> python compiler takes care of it?
No, there is no built-in macro facility. The best you can do is to quote
code to protect it from the initial compiler pass so you can manipulate it
as a runtime string before really compiling it.
Terry J. Reedy
More information about the Python-list | <urn:uuid:561e56b4-2027-4730-b5f0-d57f333483ca> | 2.59375 | 414 | Comment Section | Software Dev. | 50.17375 | 2,176 |
3. if F(x)= find F'(16)
Hi, any help would be wonderful. I really need the explanation more than the answer, though.
What are your thoughts?
1. A substitution looks easy enough. u = ???
2. Begging for Integration by Parts if you want to learn something, but a simple substitution of everything under the radical might be a lot easier.
3. A derivative of an integral? Don't forget the Chain Rule. This one likely is ill-formed, Do you mean "dt"?
Let's see what you get. | <urn:uuid:5298de05-5b0f-4c60-9328-bdf767654b17> | 2.5625 | 121 | Q&A Forum | Science & Tech. | 84.9275 | 2,177 |
Five months ago or so, Honeywell organized a series of lectures by the Nobel laureate Sheldon Glashow at the Czech Technical University (ČVUT) in Prague.
The lecture you can watch now asked the question whether science evolves by chance or by design.
It's a sort of a fun, light, philosophically and historically loaded talk.
Maybe the number of the historical episodes will be boring for you: he could be a professional historian of science right away.
Typical Czech engineering students are listening to Glashow. ;-)
But if you like the first part, continue with Part 2 and Part 3. If you make it to the third part, there will be some examples of his point from modern physics. Around 18:00, he also talks about Gell-Mann and quarks' and string theorists' delight when they deduced that string theory predicted gravity. Glashow doesn't count it as a prediction because he had known about gravity before string theory was born. Of course, from the viewpoint of the history of science, it wasn't a (new) prediction: the chronology guarantees that. However, from the viewpoint of science and the strength and validity of its hypotheses, the fact that string theory implies general relativity is exactly as important and consequential as a prediction! The chronology is just a part of the history, social science, it was accidental, and a scientist simply can't pay attention to such things.
On the other hand, I agree that both accidental discoveries as well as "planned research" have been important and will be important.
Some other not-too-demanding physics news: Australia opened the world's fastest radio telescope.
Robert Christy, a physicist who worked on the Manhattan Project and the first one who became hostile against Edward Teller after he identified Oppenheimer as a communist, died.
An 11-year-old maľchik (=Russian boy) discovered the mammoth of the century (the best preserved one in 100 years). | <urn:uuid:a311115f-012d-4f7f-a951-b597bfb31851> | 2.9375 | 410 | Personal Blog | Science & Tech. | 47.052871 | 2,178 |
Expression.Power Method (Expression, Expression, MethodInfo)
Creates a BinaryExpression that represents raising a number to a power.
Assembly: System.Core (in System.Core.dll)
public static BinaryExpression Power( Expression left, Expression right, MethodInfo method )
left or right is null.
method is not null and the method it represents returns void, is not static (Shared in Visual Basic), or does not take exactly two arguments.
method is null and the exponentiation operator is not defined for left.Type and right.Type.
method is null and left.Type and/or right.Type are not Double.
The resulting BinaryExpression has the Method property set to the implementing method. The Type property is set to the type of the node. If the node is lifted, the IsLifted and IsLiftedToNull properties are both true. Otherwise, they are false. The Conversion property is null.
The following information describes the implementing method, the node type, and whether a node is lifted.
The following rules determine the implementing method for the operation:
If method is not null and it represents a non-void, static (Shared in Visual Basic) method that takes two arguments, it is the implementing method.
Otherwise, if the Type property of either left or right represents a user-defined type that overloads the exponentiation operator, the MethodInfo that represents that method is the implementing method.
Node Type and Lifted versus Non-Lifted
If left.Type and right.Type are assignable to the corresponding argument types of the implementing method, the node is not lifted. The type of the node is the return type of the implementing method.
If the following two conditions are satisfied, the node is lifted and the type of the node is the nullable type that corresponds to the return type of the implementing method:
left.Type and right.Type are both value types of which at least one is nullable and the corresponding non-nullable types are equal to the corresponding argument types of the implementing method.
The return type of the implementing method is a non-nullable value type.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers. | <urn:uuid:86e56b94-27ab-47e0-a54e-943364d476f9> | 2.9375 | 475 | Documentation | Software Dev. | 41.277691 | 2,179 |
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From W. Ford Doolittle (2000) "Uprooting the tree of life." Scientific American, 282(2):90-5. Note that distances are not necessarily to scale in this image. This image reflects a view held by some practicing scientists (including Dr. Doolittle, the author of the original article) that there was a period in life's early history when genes swapped so frequently that it is impossible to treat those earlier lineages as truly distinct, nor to trace those lineages back cleanly to a single ancestor. They do not dispute that life has some common ancestor, but they do seek to clarify how we talk about that ancestor. | <urn:uuid:44f52721-39d5-4bb3-8599-b9d86311140d> | 2.609375 | 138 | Truncated | Science & Tech. | 51.323578 | 2,180 |
Following Oceana’s newly released report on the harmful impacts of illegal fishing, one of the questions that I as Oceana's Northeast representative was asked most often was, “Where is this happening?” The short answer: Illegal fishing happens everywhere, from the most distant waters near Antarctica to just off the U.S. coast.
This week brought great news for shark populations that are dwindling both in U.S. waters and worldwide. Today, the Delaware House of Representatives introduced a bill prohibiting the possession, trade, sale and distribution of shark fins within the state. If passed, House Bill 41 would make Delaware the first East Coast state to pass a ban on the shark fin trade, following in the footsteps of Oregon, Washington, California, Hawaii and Illinois.
Current federal law prohibits shark finning in U.S. waters, requiring that sharks be brought into port with their fins still attached. However, this law does not prohibit the sale and trade of processed fins that are imported into the country from other regions that could have weak or even nonexistent shark protections in place.
This unsustainable catch is driven by the demand for shark fins, often used as an ingredient in shark fin soup, and kills millions of sharks every year. Delaware’s bill would close the loopholes that fuel the trade and demand for fins, and ensure that the state is not a gateway for shark products to enter into other U.S. state markets.
Not only was there great news coming out of the U.S., international shark lovers have reason to celebrate as well. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), voted this week to place stricter regulations on the trade of manta rays, three species of hammerheads, oceanic whitetip and porbeagle sharks, acknowledging that these species are in dire need of protection. When countries export these species, they are required to possess special permits that prove these species were harvested sustainably. This decision will greatly curb illegal overfishing and reduce the numbers of endangered sharks killed globally.
History was made today in Bangkok, when Parties to CITES (the Convention on International Trade in Endangered Species of Wild Flora and Fauna) voted to protect five species of sharks and two species of manta rays. The seven protected species are: oceanic whitetip (Carcharhinus longimanus), porbeagle (Lamna nasus), scalloped hammerhead (Sphyrna lewini), great hammerhead (S. mokarran), smooth hammerhead (S. zygaena), oceanic manta ray (Manta birostris) and reef manta ray (M. alfredi).
All seven species are considered threatened by international trade – the sharks for their fins, and the manta rays for their gills, which are used in Traditional Chinese Medicine. CITES protection is an important complement to fisheries management measures, which, for these species, have failed to safeguard their survival.
The vote was to list the animals for protection under Appendix II which does not entail a ban on the trade, but instead means that trade must be regulated. Exporting countries are required to issue export permits, and can only do so if they can ensure that they have been legally caught, and that their trade is not detrimental to the species’ survival.
All of the proposals received the two-thirds majority needed to be accepted – but the listing is not yet final. Decisions can be overturned with another vote during the final plenary session of the meeting, which wraps up on Thursday. This is what happened with porbeagle sharks in the 2010 CITES meeting in Qatar – an Appendix II listing approved by the Committee evaporated with another vote in plenary. As a result, at that meeting, none of the proposed shark species were granted protection. Now, three years later, we’re hopeful that the international community finally sees the importance of regulating the trade that puts these animals at risk.
Keep your fingers crossed!
Happy Friday, everyone.
It's been a rough few weeks for the oceans at CITES, but now it's time to pick up the pieces. If CITES taught us anything, it's that the work of the ocean conservation community is more important than ever.
This week in ocean news,
....Rick at Malaria, Bed bugs, Sea Lice and Sunsets discussed one of the more shady aspects of CITES: the secret ballots, which were invoked for votes on bluefin tuna, sharks, polar bears, and deep water corals.
…The Washington Post reported that Maryland is cracking down on watermen who catch oysters in protected sanctuaries or with banned equipment. Once a principal source of oysters, the Chesapeake now provides less than 5 percent of the annual U.S. harvest.
…For the first time, scientists were able to use videos to observe octupuses’ behavioral responses. The result? The octupuses had no consistent reaction to one film -- in other words, they had no “personality.” Curiously, other cephalopods display consistent personalities for most of their lives.
…The New York Times wondered if the 700,000 saltwater home aquariums in the United States and the associated trade in reef invertebrates are threatening real reef ecosystems.
This is the ninth in a series of dispatches from the CITES meeting in Doha, Qatar.
As Oceana marine scientist Elizabeth Griffin put it: “This meeting was a flop.”
CITES has been a complete failure for the oceans. The one success -- the listing of the porbeagle shark under Appendix II -- was overturned yesterday in the plenary session.
“It appears that money can buy you anything, just ask Japan,” said Dave Allison, senior campaign director. “Under the crushing weight of the vast sums of money gained by unmanaged trade and exploitation of endangered marine species by Japan, China, other major trading countries and the fishing industry, the very foundation of CITES is threatened with collapse.”
Maybe next time -- if these species are still around to be protected.
The failure of CITES means that Oceana’s work – and your support and activism – is more important than ever. You can start by supporting our campaign work to protect these creatures.
Here's Oceana's Gaia Angelini on the conclusion of CITES:
This is the eighth in a series of dispatches from the CITES conference in Doha, Qatar.
More difficult news out of Doha today.
While seven of the eight proposed shark species (including several species of hammerheads, oceanic whitetip and spiny dogfish) were not included in Appendix II, the one bright spot was for the porbeagle shark, which is threatened by widespread consumption in Europe.
The porbeagle’s Appendix II listing is a huge improvement because it requires the use of export permits to ensure that the species are caught by a legal and sustainably managed fishery.
And there is a slight chance that the other shark decisions could be reversed during the plenary session in the final two days.
Here are Oceana scientists Elizabeth Griffin and Rebecca Greenberg reflecting on the shark decisions:
This is the seventh in a series of posts from CITES. Check out the rest of the dispatches from Doha here.
Eight shark species have been proposed for listing to Appendix II of CITES, including the oceanic whitetip, scalloped hammerhead, dusky, sandbar, smooth hammerhead, great hammerhead, porbeagle and spiny dogfish.
Listing these species, which are threatened by shark finning, is necessary to ensure international trade does not drive these shark species to extinction.
Here's Oceana's Ann Schroeer from our Brussels office with an optimistic outlook on the upcoming shark proposals at CITES.
This is the latest in a series of posts from CITES. See the rest of the dispatches here.
Over the weekend, CITES failed to include 31 species of red and pink coral in Appendix II, trade protections that were promised during the last CITES Conference more than two and a half years ago.
These corals are harvested to meet the growing demand for jewelry and souvenirs. The unregulated and virtually unmanaged collection and trade of these species is driving them to extinction.
Many of the corals are long-lived, reaching more than 100 years of age, and grow slowly, usually less than one millimeter in thickness per year. These colonies are fragile and extremely vulnerable to exploitation and destruction, and their biological characteristics severely limit their ability to recover.
Oceana campaign director Dave Allison had this to say about the corals decision (first video), as well as the failure of CITES to protect marine species in general (second video.)
Happy Friday, ocean fans. It's almost spring, and a surfing alpaca exists in the world. Things are looking up.
Before we get to the week's best marine tidbits, an important announcement: Oceana board member Ted Danson will be answering questions live on CNN.com on April 1, so send your ocean queries in, stat!
Also, don't forget that today is the last day to take the Ocean IQ quiz for a chance to win prizes, including a trip with SEE Turtles.
This week in ocean news,
…Yes, CITES failed to deliver on bluefin tuna yesterday, but as Monterey Bay Aquarium’s Julie Packard pointed out, at least the conversation is changing. Bluefin is now in the same rhetorical realm as endangered land creatures such as tigers and elephants.
…Deep Sea News wrote a requiem for a robot -- the Autonomous Benthic Explorer (ABE) that was lost at sea last week during a research expedition to the Chilean Subduction Zone. On a recent dive, ABE had detected evidence of hydrothermal vents. At the time of its loss, ABE had just begun a second dive to home into a vent site and photograph it.
This is the fifth in a series of dispatches from CITES. You can read the other dispatches here.
Although there were repeated calls from delegates from the E.U., U.S. and Monaco to allow time for parties to meet and arrive at a compromise position, a Libya delegate forced a preemptory vote on the E.U. proposal, which resulted in a 43 to 72 vote, with 14 abstaining.
Campaign director Dave Allison called the defeat "a clear win by short-term economic interest over the long-term health of the ocean and the rebuilding of Atlantic bluefin tuna populations."
The decision could spell the beginning of the end for the tigers of the sea.
Here's Oceana's Maria Jose Cornax on the decision: | <urn:uuid:d2464720-2e87-4061-9f5b-3ccfe0c3f6db> | 2.96875 | 2,336 | Personal Blog | Science & Tech. | 47.470113 | 2,181 |
Jan 19, 2001, 2:38 PM
Post #1 of 1
(From the Perl FAQ)
How do I find the week-of-the-year/day-of-the-year
How do I find the week-of-the-year/day-of-the-year?
The day of the year is in the array returned by localtime() (see localtime):
or more legibly (in 5.004 or higher):
$day_of_year = (localtime(time()));
You can find the week of the year by dividing this by 7:
$day_of_year = localtime(time())->yday;
Of course, this believes that weeks start at zero. The Date::Calc module from CPAN has a lot of date calculation functions, including day of the year, week of the year, and so on. Note that not all business consider ``week 1'' to be the same; for example, American business often consider the first week with a Monday in it to be Work Week #1, despite ISO 8601, which consider WW1 to be the frist week with a Thursday in it.
$week_of_year = int($day_of_year / 7); | <urn:uuid:af9f3503-6cea-48e0-8658-c9f6bc9a8961> | 2.9375 | 265 | Comment Section | Software Dev. | 60.978311 | 2,182 |
Australian researchers Thursday revealed they had filmed a pod of extremely rare Shepherd's beaked whales for the first time ever.
The Australian Antarctic Division team was tracking blue whales off the coast of Victoria state last month when they spotted the reclusive mammals, which are so rarely seen that no population estimates of the species exist.
Voyage leader Michael Double said the black and cream-coloured mammals with prominent dolphin-like beaks had been spotted in the wild only a handful of times through history.
According to the Australian environment department, there have only been two previous confirmed sightings -- a lone individual in New Zealand and a group of three in Western Australia
They have never been filmed live before.
"These animals are practically entirely known from stranded dead whales, and there haven't been many of them," Double told AFP, calling the footage "unique".
"They are an offshore animal, occupying deep water, and when they surface it is only for a very short period of time."
Double said what was remarkable about the sighting was that the whale was previously thought to be a solitary creature, yet was in a pod of 10 to 12.
"To find them in a pod is very exciting and will change the guide books. Our two whale experts will now carefully study the footage to work out the whale sizes and so on and prepare a scientific paper."
The Shepherd's beaked whale, also known as the Tasman beaked whale, was discovered in 1937 but little is known about them.
Explore further: The pirate ant: A new species from the Philippines with a bizarre pigmentation pattern | <urn:uuid:d651b44a-235d-408d-b0da-145009d131c5> | 3.5 | 322 | News Article | Science & Tech. | 38.538599 | 2,183 |
Two new species of frog have been discovered in fast-disappearing forests in the Philippines, boosting hopes for the survival of the country's rich but threatened wildlife, scientists said Tuesday.
The new discoveries are a mottled brown frog with red eyes and a broad yellow stripe running down its back, and a yellow-green one not much bigger than a human thumb, British-based Fauna and Flora International said.
Country director Aldrin Mallari said the finds should boost conservation efforts in the Philippines, which has extremely diverse plant and animal life but where many species are threatened by extinction.
"Many (environmental) institutions and funding agencies have written off the Philippines because we only have 20 percent of our forests left," he said at a forum at the National Museum where the finds were announced to the public.
"Yet many of these species, even if they are threatened, have this resiliency."
His team discovered the frogs in Leyte island's Nacolod mountain range in November last year. Their dwindling habitat also harboured 62 other reptiles and amphibian species, 36 mammal species, 112 bird species, and 229 plant species.
"A lot of these are critically endangered because of fragmentation," Mallari said.
The Nacolod range's once-expansive forest cover is almost gone, with trees cut down for timber or burnt off to free up land for farming, he said. The remaining patches of forest are no longer visible by satellite.
The long-term survival of the diverse species will depend on the Philippines' ability to protect habitats from further exploitation, Mallari said.
The brown frog specimens measured about 43-55 millimetres (1.7-2.2 inches) while the yellow-green ones were 20-27 millimetres (0.8-1.1 inches) long. They have not yet been formally named.
US-based Conservation International lists the Philippines both as one of the 17 countries that harbour most of Earth's plant and animal life, and a "biodiversity hotspot" due to massive habitat loss.
Theresa Lim, wildlife protection chief of the Department of Environment and Natural Resources, told the forum that despite this, apart from the frogs 36 new plant and animal species were discovered in the Philippines in the past 10 years.
"We have to do something. We don't want them to disappear immediately after they are discovered," she said.
Explore further: The pirate ant: A new species from the Philippines with a bizarre pigmentation pattern | <urn:uuid:c840d3a7-e583-49d7-a7bb-595fab4e8d92> | 3.546875 | 517 | News Article | Science & Tech. | 43.865264 | 2,184 |
At first glance, there's nothing remarkable about the rocky Maine blueberry field in which University of Maine graduate student Nancy Price does her research. But those rocks are crucial to our understanding about how faults work nearly 10 miles below the surface of the Earth. Indeed, thats where rocks are supposedly the strongest.
Prices findings suggest that geophysical assumptions about the strength of faults at different depths may need to be reevaluated. And if we better understand faults, we may be able to better predict the behavior that causes large earthquakes.
Price is studying the Norumbega fault system, a line of ancient faults that cuts across Maine from Calais to Casco Bay. The now extinct faults were seismically active millions of years ago. Today, the Norumbega system is considered an ancient analog for major earthquake faults, such as the San Andreas fault in California and the North Anatolian fault in Turkey, which have produced some of the deadliest quakes in our time.
Like the San Andreas, the Norumbega is a strike-slip fault where only the shallowest parts are exposed or can be reached by drilling. To study deeper fault rocks, an ancient, extinct zone must be found where the depths have been exposed through exhumation and erosion.
Price is studying a part of the Norumbega fault in Windsor, Maine, that more than 300 million years ago was situated about 10 miles below the surface, but is now exposed. In a strike-slip fault, two tectonic plates slide against each other. They do not slide smoothly and stress builds up as the plates snag on each other.
Close to the surface, where the rocks are relatively cold, the plates are brittle and rocks break, easily releasing the stress. Temperature increases with depth in the Earth, and at a certain temperature the rock weakens and stretches like chewing gum. The strongest part of the crust lies at the depth where the rock starts to stretch, but can also still crack, a region called the frictional-viscous transition. This is the depth level Price is studying.
How this region behaves is the key to how the fault works, says Price, who earned a masters degree at the University of Massachusetts Amherst. If we understood it, we wouldnt have to rely on how often an earthquake ruptures. We could model the fault based on what we understand of the physics of how the rock will behave and predict what will happen.
Working with geologist Scott Johnson, chair of UMaines Department of Earth Sciences, Price originally set out to model the fault using data collected from hundreds of rock samples that were once in the transition zone. These sheared fault rocks contain thin, gray veins called pseudotachylyte evidence of ancient earthquakes.
But when Prices samples revealed more pseudotachylyte than expected, she turned her attention to identifying how much of the rock contained these veins and how this might change assumptions of fault strength at these depths.
Price found the process of pseudotachylyte formation causes the size of the mineral grains in the rock to be smaller and the percentages of the minerals to change, causing the thin gray layer to be weaker than the rest of the rock. If enough pseudotachylyte from earthquakes is created over millions of years, the fault itself becomes weaker than is generally accepted.
This change in perspective will help drive discussion, Price says.
Explore further: Origins of human culture linked to rapid climate change | <urn:uuid:b4acb821-aaf6-47a3-943f-1c072d72f5a3> | 4.3125 | 704 | News Article | Science & Tech. | 44.230096 | 2,185 |
One of the Sun's greatest mysteries is about to be unravelled by UK solar astrophysicists hosting a major international workshop at the University of St Andrews from September 6-9th 2004. For years scientists have been baffled by the 'coronal heating problem': why it is that the light surface of the Sun (and all other solar-like stars) has a temperature of about 6000 degrees Celsius, yet the corona (the crown of light we see around the moon at a total eclipse) is at a temperature of two million degrees?
Understanding our nearest star is important because its behaviour has such an immense impact on our planet. This star provides all the light, heat and energy required for life on Earth and yet there is still much about the Sun that is shrouded in mystery.
"The problem is like an Astrophysics X-file! It is totally counter intuitive that the Sun's temperature should rise as you move away from the hot surface," explains Dr Robert Walsh of the University of Central Lancashire and co-organiser of the workshop. "It is like walking away from a fire and suddenly hitting a hotspot, thousands of times hotter than the fire itself."
Using the joint ESA/NASA satellite, the Solar and Heliospheric Observatory (SOHO), along with another NASA mission called TRACE, researchers have gathered enough data to form two rival theories to explain what has been termed 'coronal heating'. It is now believed that the Sun's strong magnetic field is the culprit behind this unique phenomenon. At this SOHO workshop, scientists from the UK and around the world will look at the evidence for these two explanations and try to untangle the clues we now have available to us.
Walsh continues, "SOHO's contribution to the research has been so important because for the first time we can take simultaneous magnetic and extreme ultraviolet images of the Sun's atmosphere, allowing us to study the changes in the magnetic field at the same time as the corresponding effect in the corona. Then, using sophisticated computer simulations, we have constructed 3d models of the coronal magnetic field that can be compared with SOHO's observations."
One possible mechanism for coronal heating is called 'wave heating'. Prof Alan Hood from the Solar and Magnetospheric Theory Group at St. Andrews explains: "The Sun has a very strong magnetic field which can carry waves upwards from the bubbling solar surface. Then these waves dump their energy in the corona, like ordinary ocean waves crashing on a beach. The energy of the wave has to go somewhere and in the corona it heats the electrified gases to incredible temperatures."
The other rival mechanism is dependent on twisting the Sun's magnetic field beyond breaking point. Prof Richard Harrison of the UK's Rutherford Appleton Laboratory says "The Sun's magnetic field has loops, known to be involved in the processes of sun spots and solar flares. These loops reach out into the Sun's corona and can become twisted. Like a rubber band, they can become so twisted that eventually they snap. When that happens, they release their energy explosively, heating the coronal gases very rapidly".
The Sun is the only star astronomers can study in close detail and many questions remain. The workshop will also look forwards to future missions such as Solar-B, STEREO and Solar Orbiter that all have important UK involvement through PPARC.
Source: The Particle Physics and Astronomy Research Council
Explore further: Moore tornado a rarity, experts say | <urn:uuid:20dd75da-7eb0-4444-8a79-97d011969912> | 3.84375 | 712 | News Article | Science & Tech. | 38.521582 | 2,186 |
It is probably too complicated to be sure, with subtle shifts in air flow easily affecting the total drag.
However, since things (usually) tend towards their lowest energy, and the wheels tend to spin when the car is moving, I would guess that is the lowest energy state, and hence the lowest total drag, compared to clamping the brakes on the bike wheel and stopping it from spinning.
But that statement, lowest energy state, and hence the lowest total drag, is BS. Things have no tendency towards a state of lowest energy dissipation!
Drag on the car * speed = power from the car.
power from the car = power from the spinning wheel + everything else
Increased drag on the car = power the spinning wheel generates / speed
If the wheel does not spin, it does no work.
If the wheel spins freely, it does -very little work-, because it has very little friction. So the spinning wheel adds very little more drag than the fixed one. | <urn:uuid:9b5e6be3-23a7-4a63-96e6-5aabdc110848> | 2.5625 | 201 | Q&A Forum | Science & Tech. | 57.956829 | 2,187 |
What is the height of the electron orbits an atom? (How far are the energy levels of the electron relative to the center of the atomic nucleus?)
How fast do electrons move in their orbits?
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3 months ago | <urn:uuid:5536d8e1-37ac-451a-8f68-3b5d9fa0db2d> | 2.765625 | 75 | Q&A Forum | Science & Tech. | 60.108952 | 2,188 |
Major Section: PROGRAMMING
(String>= str1 str2) is non-
nil if and only if the string
str2 precedes the string
str1 lexicographically or the strings
are equal. When non-
(string>= str1 str2) is the first
position (zero-based) at which the strings differ, if they differ,
and otherwise is their common length. See string>.
The guard for
string>= specifies that its arguments are strings.
String>= is a Common Lisp function. See any Common Lisp
documentation for more information. | <urn:uuid:f21634d9-a686-41dd-996c-a1120e1fab7e> | 2.921875 | 127 | Documentation | Software Dev. | 69.65592 | 2,189 |
Stephen Hawking was once told by an editor that every equation in a book would halve the sales. Curiously, the opposite seems to happen when it comes to research papers. Include a bit of maths in the abstract (a kind of summary) and people rate your paper higher — even if the maths makes no sense at all. At least this is what a study published in the Journal Judgment and decision making seems to suggests.
Maths: incomprehensible but impressive?
Kimmo Eriksson, the author of the study, took two abstracts from papers published in respected research journals. One paper was in evolutionary anthropology and the other in sociology. He gave these two abstracts to 200 people, all experienced in reading research papers and all with a postgraduate degree, and asked them to rate the quality of the research described in the abstracts. What the 200 participants didn't know is that Eriksson had randomly added a bit of maths to one of the two abstracts they were looking at. It came in the shape of the following sentence, taken from a third and unrelated paper:
A mathematical model is developed to describe sequential effects.
That sentence made absolutely no sense in either context.
People with degrees in maths, science and technology weren't fooled by the fake maths, but those with degrees in other areas, such as the humanities, social sciences and education, were: they rated the abstract with the tacked-on sentence higher. "The experimental results suggest a bias for nonsense maths in judgements of quality of research," says Eriksson in his paper.
The effect is probably down to a basic feature of human nature: we tend to be in awe of things we feel we can't understand. Maths, with its reassuring ring of objectivity and definiteness, can boost the credibility of research results. This can be perfectly legitimate: maths is a useful tool in many areas outside of hard science. But Eriksson, who moved from pure maths to interdisciplinary work in social science and cultural studies, isn't entirely happy with the way it is being used in these fields. "In areas like sociology or evolutionary anthropology I found mathematics often to be used in ways that from my viewpoint were illegitimate, such as to make a point that would better be made with only simple logic, or to uncritically take properties of a mathematical model to be properties of the real world, or to include mathematics to make a paper look more impressive," he says in his paper. "If mathematics is held in awe in an unhealthy way, its use is not subjected to sufficient levels of critical thinking." | <urn:uuid:83bef79a-67ad-4915-8924-64a3293a8acb> | 2.65625 | 526 | Knowledge Article | Science & Tech. | 37.756831 | 2,190 |
Reply to comment
R is the radius of the Earth, H is your height and D is how far you can see.
...You can see forever, according to Alan Lerner's Broadway musical. But can you? How far can you see? Just how far away is the horizon?
Let's assume the Earth is smooth and spherical, so no intervening hills obscure your view, and ignore the effects of light refraction as it passes through the atmosphere, along with the effects of any rain or fog. If your eyes are a height above the ground and you look towards the horizon, then the distance to the horizon, , is one side of a right-angled triangle whose other two sides are plus the radius of the Earth, and . Using Pythagoras' theorem for this triangle we have
The wanderer above the sea of fog by Caspar David Friedrich.
Since the average radius of the Earth is about 6400 km and much greater than your height , we can neglect compared to when multiplying out the square of . This means that the straight-line distance to the horizon is just
to a very good approximation. If we put the radius of the Earth into the formula we get (measuring in metres)
For someone of height 1.8m we have and the distance to the horizon is metres, or 3 miles to very good accuracy. Notice that the distance that you can see increases like the square root of the height that you are viewing from, so if you go to the top of a hill that is 180 metres high you will be able to see about ten times further. From the top of the world's tallest building, the Burj Dubai in the Emirates you might see for 102 kilometres, or 64 miles. From the summit of Mount Everest you might see for 336 kilometres, or 210 miles - not quite forever, but far enough.
Problem 1: Above we have calculated the straight-line distance to the horizon point. Show that if we take the curvature of the Earth into account, then the "walking" distance over the Earth's surface to the horizon point is
Problem 2: You see something, like a cloud or a hot air balloon, high in the sky beyond the horizon and you know its maximum possible height above the ground. Can you work out how far away it could be? | <urn:uuid:be8d6eac-981c-4791-b274-c9a72495a608> | 3.203125 | 469 | Comment Section | Science & Tech. | 67.198969 | 2,191 |
September 28, 2010
Priority queues are a data structure in which items arrive in random order and exit in priority order; they provide the operations find-min, delete-min, insert and merge. We implemented priority queues using leftist heaps in one exercise and using pairing heaps in another exercise. In today’s exercise, we will implement priority queues using the maxiphobic heaps of Chris Okasaki.
Maxiphobic heaps are a variant of leftist heaps. Like leftist heaps, maxiphobic heaps are represented as binary trees arranged according to the heap property that every element is less than or equal to its two children. Find-min looks at the root of the tree, delete-min discards the root and merges its two children, and insert merges the existing tree with a singleton tree containing the new element.
The key to leftist trees and maxiphobic trees is the merge operation. In leftist trees, the rank of each left child is always less than the rank of its sibling, where the rank of a node is defined as the length of its right spine, and the merge operation enforces this invariant. In maxiphobic trees, the merge operation is implemented by comparing the roots of the two trees. The smaller root survives as the root of the merged tree. That leaves three sub-trees: the tree that lost in the comparison of the two roots, and the child sub-trees of the winner. They are merged by first merging the two smaller trees, where the size of a tree is determined as the number of elements it contains, then attaching that merged tree along with the remaining tree as the children of the new root. The name maxiphobic, meaning “biggest avoiding,” refers to the merge of the two smaller sub-trees.
Your task is to write functions that implement maxiphobic trees. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.
Pages: 1 2 | <urn:uuid:e3e559af-1a88-484f-b256-84886ec33b81> | 3.515625 | 423 | Tutorial | Software Dev. | 49.141857 | 2,192 |
I'll not make modifications to the text except for differences between C and Python.
You can find the first part of this article here: Writing a Widget Using Cairo and PyGTK 2.8
Making the clock run is as simple as starting a timer that calls a callback. However, we might also want to be able to set a different time on our clock, so we'll store the time for the clock inside the widget. We don't want to let people change the time directly, in object-orientation speak, we want to make the time variable private.
Python, in its "trust the programmer" philosophy usually use a convention (the single "_" underscore) to identify a variable as private. I implemented the public API as a property in this way:
# public access to the time member def _get_time(self): return self._time def _set_time(self, datetime): self._time = datetime self.redraw_canvas() time = property(_get_time, _set_time)
Now you can externally access the time property as if it's a simple object member.
We can use the property in the update() method which will update the clock with the new time:
def update(self): # update the time self.time = datetime.now() return True # keep running this event
Notice that this method returns a boolean value (true). Functions passed as timeout events return a boolean value. If the value is true, the event will be run again; if the value is false it will not. There is also a method that we haven't defined yet, redraw_canvas(). This method will redraw the canvas for us. From the manual page for GtkDrawingArea (our parent class), we are told to use gdk.Window.invalidate_rect(), to reexpose the canvas (and cause it to redraw). In order to make our event happen now, we should also call gdk.Window.process_all_updates(). Our redraw function looks like this:
def redraw_canvas(self): if self.window: alloc = self.get_allocation() rect = gdk.Rectangle(0, 0, alloc.width, alloc.height) self.window.invalidate_rect(rect, True) self.window.process_updates(True)
Drawing the hands requires us to think about a little geometry. For the hour hand, the hand is rotated around 30� for each hour and then a 1/2� more per minute.
So to draw the hour hand, we might do something like:
context.save() context.set_line_width(2.5 * context.get_line_width()) context.move_to(x, y) context.line_to(x + radius / 2 * math.sin( math.pi / 6 * hours + math.pi / 360 * minutes), y + radius / 2 * -math.cos( math.pi / 6 * hours + math.pi / 360 * minutes)) context.stroke() context.restore()
The minute hand and the seconds hand each rotate 6° per minute/second. The minute hand is easily implemented as:
context.move_to(x, y) context.line_to(x + radius * 0.75 * math.sin(math.pi / 30 * minutes), y + radius * 0.75 * -math.cos(math.pi / 30 * minutes)) context.stroke()
Finally, we need to set it running, in __init__() we will add our timeout function:
def __init__(self): super(EggClockFace, self).__init__() self.connect("expose_event", self.expose) # make it private self._time = None self.update() # update the clock once a second gobject.timeout_add(1000, self.update)
We're left with clock_ex4.py which you can run with:
$ python clock_ex4.py
and should look like this:
The animated GIF of the clock ticking was done with a tool called byzanz. I simply recorded 60 seconds of the clock. In order to find out the window location for byzanz-record, I added this to the main function after gtk.Widget.show_all():
rect = gdk.Rectangle() rect = window.window.get_frame_extents() print "-x %i -y %i -w %i -h %i" % (rect.x, rect.y, rect.width, rect.height)
This printed settings that I could paste onto my other command line:
$ byzanz-record -d 60 $GEOMETRY -l clock.gif
So far we've written a GObject with opaque property storage and we've used Cairo to draw our clock face. However the GTK+ widgets we commonly interact with also offer public APIs and emit signals to notify us when certain events take place. We will add a signal to say when someone is dragging the minute hand around.
Firstly we need to decide on what our signal is going to send and add this our file. We will implement a "time_changed" signal that along with the object also gives the time in hours and minutes that the clock has now been set to. If we were connecting this signal, our callback would look something like this:
def time_changed_cb(widget, hours, minutes): pass
Finally we need to register our signal in the class:
__gsignals__ = dict(time_changed=(gobject.SIGNAL_RUN_FIRST, gobject.TYPE_NONE, (gobject.TYPE_INT, gobject.TYPE_INT)))
More information on gobject.signal_new can be found in the documentation.
Next we have to implement a button_press_event handler so that we can determine when someone has actually clicked on a hand. We can override the signals for button_press_event, button_release_event and motion_notify_handler at the same time as replacing the expose_event. In __init()__:
self.connect("expose_event", self.expose) self.connect("button_press_event", self.button_press) self.connect("button_release_event", self.button_release) self.connect("motion_notify_event", self.motion_notify)
From reading the documentation for GtkDrawingArea, our parent class, you will see that button events and motion events are masked out, so we will need to set them so that we receive events for processing. We need to do this for each EggClockFace, so in __init__() we'll add:
self.add_events(gdk.BUTTON_PRESS_MASK | gdk.BUTTON_RELEASE_MASK | gdk.POINTER_MOTION_MASK)
The line formed by the bearing of the hand is infinitely thin, so we can't expect a user to be able to click on it. It would be nice to detect if the user clicked within 5 pixels of the line. To do this we require some more geometry.
We know that (sin φ, cos φ) is a point on the unit circle, that is it has magnitude 1. Thus a vector from the origin to (sin φ, cos φ) will be a unit vector, we will name it l. We will also take a vector p which is the vector from the origin to the point where the user clicked.
This would give vector components equal to:
px = event.x - widget.get_allocation().width / 2 py = widget.get_allocation().height / 2 - event.y lx = math.sin(math.pi / 30 * minutes) ly = math.cos(math.pi / 30 * minutes)
Simple reasoning will tell us that there exists a point ul where l is perpendicular to (ul – p) (which is the shortest distance between the point and the line and is what we want to measure).
We can project p onto l using the dot product such that u = p.l. The dot product can be done mathematically like so:
u = lx * px + ly * py
If u comes out to be a negative number we'll ignore it, this means that the user clicked on the opposite side of the clock to where the hand is. Finally, the magnitude of the distance can be found. If the magnitude of the distance (squared) is less then 5 pixels (squared) we can set the private member _dragging to be true (we used squared values here because we have no need to do a slow sqrt()).
if u < 0: return False d2 = math.pow(px - u * lx, 2) + math.pow(py - u * ly, 2) if d2 < 25: # 5 pixels away from the line self._dragging = True
We now need to implement handlers for the motion_notify_event and button_release_event. Both of these signal handlers share a lot of their code, so we can move it out into another method, emit_time_changed_signal(). The geometry for this method is simply the reverse of the geometry that we used to draw the hands on the clock face.
def emit_time_changed_signal(self, x, y): # decode the minute hand # normalize the coordinates around the origin x -= self.get_allocation().width / 2 y -= self.get_allocation().height / 2 # phi is a bearing from north clockwise, use the same geometry as we # did to position the minute hand originally phi = math.atan2(x, -y) if phi < 0: phi += math.pi * 2 hour = self.time.hour minute = phi * 30 / math.pi # update the offset self._minute_offset = minute - self.time.minute self.redraw_canvas() self.emit("time_changed", hour, minute)
The time_changed signal is actually sent to all listeners by emit(). You may also notice the variable _minute_offset, we use this to know how far out of phase the minute hand is with the current time. This offset has to be added to any other requests for the current time. I will leave it as an exercise to the reader to implement a similar offset for the hour hand.
After all of this our two signals handlers from above are simply:
def motion_notify(self, widget, event): if self._dragging: self.emit_time_changed_signal(event.x, event.y) def button_release(self, widget, event): if self._dragging: self._dragging = False self.emit_time_changed_signal(event.x, event.y) return False
Of course, in order to find out when our signal is emitted, we only need to connect a signal handler to the clock in main():
clock.connect("time_changed", time_changed_cb) def time_changed_cb(widget, hours, minutes): print "::time-changed - %02i:%02i" % (hours, minutes)
Putting it all together, you should have clock_ex5.py.
That's it! You now know how to implement a GObject, draw things inside that GObject, add private data, add signals and animate the object. This forms pretty much everything you need to write your own GtkWidget.
UPDATE: thanks to Johan Dahlin for the hints on __gsignals__. | <urn:uuid:991c61ab-a7c8-4839-b688-fd580365f019> | 2.859375 | 2,503 | Documentation | Software Dev. | 64.84767 | 2,193 |
Parthenogenesis in New Zealand Stick Insects
[Read before the 8th N.Z. Science Congress, in Auckland, May 20, 1954; reccived by the Editor, May 24, 1954.]
The phenomenon of parthenogenesis is known to occur in many species of phasmids, but it has not hitherto been recorded among the phasmids of New Zealand. Most species of the genus Clitarchus can reproduce parthenogenetically as well as sexually and both processes of reproduction apparently occur together With the exception of the species Acanthoxyla senta, found only on the Three Kings Islands, all the species of the genus Acanthoxyla reproduce parthenogenetically. Breeding experiments carried out over periods of four to six years with four species of Acanthoxyla have failed to produce any males. These are considered to represent the parthenogenetic species in which the male has been completely suppressed. The seven parthenogenetic forms of Acanthoxyla form a “parthenogenetic ring” of closely lelated but quite distinct species in which this relationship could probably be varied only by the intervention of a functioning male.
Parthenogenesis is of common occurrence amongst insects, and is known to occur in many species of Phasmids. The Indian and South European species upon which much research has been done, breed almost entirely parthenogenetically. It is not surprising, therefore, to find the phenomenon of parthenogenesis of widespread occurrence in several genera of New Zealand stick insects. My attention was first drawn to this some years ago when I commenced breeding different New Zealand species in an attempt to relate male forms to their correct females. From these experiments 1 soon learned that parthenogenesis was of frequent occurrence among species of Clitarchus and Acanthoxyla and that it also occurred in certain species of Mimarchus, but was absent or very rare in the species belonging to Argosarchus. Although these breeding experiments have satisfactorily solved the relationships of the different male and female forms of stick insects found in New Zealand, they have not completely solved the riddle of parthenogenesis, but I thought that it might be appropriate at this stage to make public what I have so far learned on this subject.
The common smooth green or brown stick insect, found all over the country, belongs to the genus Clitarchus Stal, and is known as C. hookeri (White). C. hookeri breeds both by parthenogenesis and by the normal sexual mating process. Eggs from a mated female give rise to both male and female offspring, but eggs developing parthenogenetically give rise only to females. The genus Clitarchus also contains another new species, at present undescribed, and in which no male has so far been found, neither in the field nor by breeding. A female hookeri, taken in the field and kept alive in the laboratory, produced about 200 eggs from the hatchings of which I selected six females. These females were segregated before maturity so that their offispring would be reproduced parthenogenetically. At the same time in another group six females and six males were segregated together to ensure that their offspring would develop from fertilised eggs. Each
of these series was inbred and kept going for six years, and each series produced one generation per year. At the end of this period the mated series was as vigorous as ever, but in the seventh year all the parthenogenetic females but one died before maturity. The one that survived was well below normal size and laid only eleven eggs. These eggs were also smaller than normal and none of them hate led. During the six years of parthenogenetic breeding there was always a very he ivy mortality of nymphs during the second instar which, so far as I could ascertain by feeding experiments, was not due to dietary or water deficiencies. At no time during this parthenogenetic breeding was a recognisable male produced. The possibility of males having been produced but dying before they could be recognised cannot be discounted, though I think that it is extremely unlikely. A further series of hookeri which was bred parthenogenetically for four years and in which the originating female came from Cuvier Island gave very similar results. The average length had diminished from 8.3 cms. to 6.6 cms. over this period, though in the first parthenogenetic generation the average length was slightly greater than normal, a phenomenon I was to notice in conducting similar experiments with species of Acanthoxyla In both these parthenogenetic series of C. hookeri, with the exception of the length of the body, the morphological characteristics of the species did not vary to any great extent. For example, the spines on the fore femora varied between five and seven, a percentage of variation which is much less than that found often between odd specimens taken at random in the field. This is in approximate agreement with Weismann's views on parthenogenesis (1893), but contrary to those of Warren (1899) dealing with parthenogenesis in Daphnia, and of Ling Roth (1920) dealing with the phasmid Carausius morosus.
It would appear from these observations that the species C. hookeri, though it can reproduce parthenogenetically, cannot continue to perpetuate itself indefinitely by this means, at any rate while kept in captivity. This is in strange contrast to the undescribed species of Clitarchus, which apparently reproduces only by parthenogenesis.
The genus Acanthoxyla was set up in 1944 by Uvarov for the species previously known as Acanthoderus prasinus Westwood and its related forms. This genus includes all those spiny or tuberculated species in which the operculum of the female it provided with a basal spine or large tubercle. Besides the species prasina the genus also includes forms described under the names geisovii (Kaup), suteri (Hutton), senta Salmon and the four new forms, A. inermis, A. intermedia, A. huttoni and A. speciosa described elsewhere in this volume. Of all these species the only one in which a male is known is A. senta, which occurs only on the Three Kings Islands. The remaining species are found practically throughout New Zealand, but none of them occur on the Three Kings In all of them females only are known, and breeding experiments so far conducted have failed to produce any males. According to Hutton the species geisovii was described by Kaup from a male specimen; how Hutton came to this conclusion I do not know, as Kaup does not mention the insect's sex in his description. Intensive collection from all over the country and breeding experiments in which several thousands of specimens have been handled have both failed to yield a single male specimen of the form we call geisovii. In these breeding experiments four species of Acanthoxyla have been tried, including geisovii, prasina and two of the new species. All these were kept going for periods of four years, and in
all but one the species continued to breed true to form with small but quite noticeable variation. In the aberrant specimens-the number and positions of spines and tubercles did vary appreciably from generation to generation or between individuals of the same generation. This variation, however, was never of sufficient magnitude to constitute a new species. It is curious that in these Phasmids the first generation in captivity usually shows a small increase in length over the length of the originating female With geisovii in the fourth year there was also a noticeable diminution in the length of the body and in the number of eggs laid. The other three species still appeared to be quite vigorous, but the experiments had to be stopped at this stage for unexpected reasons. It would appear, therefore, that in the genus Acanthoxyla we have seven parthenogenetic species each of winch breeds true to form and can always be recognised as distinct. When I first began collecting these Acanthoxyla species I at first thought that Hutton had been wrong in recognising four distinct species. They all appeared to me to be but variations of one common type, but the results obtained from breeding experiments confirmed that these forms were, indeed, distinct species. As a result, I now recognise eight species of Acanthoxyla, all but one of which reproduce only by parthenogenesis.
Among insects exhibiting agamic reproduction it has been found that the somatic cells are diploid in some, and haploid in others. In haploid parthenogenesis males only are produced (eg., hive bees) whereas in diploid parthenogenesis both males and females can be produced (e.g, aphids). I have not made any cytological investigations into the condition of the body cells of any of the New Zealand phasmids but I should expect them to be in the diploid condition, in which case parthenogenetic development could normally be expected to produce males at regular though perhaps lengthy intervals. In all experiments I conducted the parthenogenesis exhibited by the species of Chtarchus and Acanthoxyla prdouced females only, and is, therefore, somewhat unusual. In the species C. hookeri parthenogenetic reproduction appeared to be quite sporadic and did not alternate with regular periods of sexual reproduction, and I consider that the phenomenon is not so highly developed in this species as in the species of Acanthoxyla. C. hookeri apparently resorts to parthenogenesis only in the absence of males. These results are in close agreement with what has so far been discovered in connection with parthenogenesis in the European phasmids. Bacillus (gallicus and Bacillus rossii, as well as with the Indian species Carausius, morosus. Various workers on this problem of parthenogenesis in phasmids have shown that the phenomenon is almost universal amongst these insects and that in the entirely parthenogenetic forms such as B. gallicus, B. rossii and C. morosus. males are very rarely produced. When they do occur these males are generally gynandromorphs. Pure functional males capable of a successful copulation are extremely rare.
It would seem to me that, in these parthenogenetic phasmids, we see an evolutionary trend which tends to dispense with the male form and which ultimately gives rise to a series of parthenogenetic species that continually breed true. We see the process started but not complete in C. hookeri, while in the seven New Zealand mainland species of Acanthoxyla we see it completed. In Acanthoxyla I regard it as forming what I would term a “parthenogenetic ring” of closely linked or related species Quite possibly these species first arose as variations from normal sexual matings which were immediately capable of parthenogenetic
reproduction. If males should ever appear and, if they were functional, I should expect the progeny from a mating to produce variations equivalent to the species of the parthenogenetic ring. On the other hand, if males are entirely suppressed then we should expect these species to be fixed within certain limits and incapable of any great morphological variation from their norms, and this appears to be the case in these New Zealand species.
This continual variation round a norm can be depicted as a circle or ellipse. If the variations of these seven parthenogenetic species are plotted around the circle (1–7) we obtain a diagram as shown in Fig. 1, in which each species varies on either side of the axes AA1, BB1, etc. As each species varies irregularly, it cannot be represented by a circle, but plots, instead, an elliptical figure and the inward limits of these seven figures subtend a further circle A-G, which should demarcate the limits of variation of the originating form. In the case of Acanthoxyla, this originating form from which the parthenogenetic species presumably arose, gives us a concept of the characters of the genus. This diagrammatic concept of variation might be applied to other groups of variant species, not necessarily parthenogenetic, with equally interesting results. | <urn:uuid:18c1a278-17d8-4b3c-b590-ba12f1601f0b> | 2.921875 | 2,542 | Academic Writing | Science & Tech. | 31.636829 | 2,194 |
Arguably the most exciting concept in the entire field of zoology is the thought that new large terrestrial tetrapod species await discovery. And despite statements from journalists and scientists, history demonstrates that the continued discovery of such animals is not an extraordinary or unexpected event. You will know this if you are familiar with such animals as the Saola Pseudoryx nghetinhensis (named in 1993), Giant muntjac Megamuntiacus vuquangensis (named in 1994), Truong Son muntjac Muntiacus truongsonensis (named in 1998), Leaf deer M. putaoensis (named in 1999), Dingiso Dendrolagus mbaiso (named in 1995: shown in adjacent image), Small red brocket Mazama bororo (named in 1996), Arunachal macaque Macaca munzala (named in 2004) and Kipunji Rungwecebus kipunji (named in 2005).
Several studies have emphasized the fact that new terrestrial mammal species are not uncommon (Heuvelmans 1983, Pine 1994, Patterson 2000, 2001, 2002, Collen & Gittleman 2004), and it is not true that all such taxa are small-bodied, nor are they all rodents and bats, nor are they all discovered in molecular laboratories or museum collections (for the record, in the discussion here I am only referring to new species discovered in the field, and not those that are discovered in museum drawers, or result from taxonomic revisions [such as Aggarwal et al.'s (2007) naming of the two new Indian wolf species, Canis himalayensis and C. indica. That's right, two new extant canid species named this year]).
New terrestrial mammals, such as those listed above, have come from SE Asia, tropical Africa and New Guinea, but one of the most notable hotspots has been Amazonia. Research here had led to the description of multiple new opossums, shrews, bats, rodents and primates, with the recognition of multiple new species of the latter group perhaps receiving most attention. On this issue, few living people have contributed so much to the discovery and documentation of new terrestrial mammal species as Dutch primatologist Dr Marc van Roosmalen [shown at left: but not the little furry chap, that's a woolly monkey]. If you know anything about the new mammal species that have been named within the last 20 years, or about the primates of Amazonia, you will already have read an awful lot about him. Articles and items about van Roosmalen and his research have appeared in Time Magazine, National Geographic, on CNN and BBC news. He has been the recipient of many grants, and is well decorated with impressive awards and titles. His contributions have been honoured by other mammalogists: Voss & da Silva (2001), for example, named the tree porcupine Coendou roosmalenorum after van Roosmalen and his son Tomas (free pdf here).
The discoveries that have kept van Roosmalen in the international science news have predominantly been of monkeys: he has described and named some of these new species himself, while in other cases they have been described and named by others. The first of his discoveries, the Black-crowned dwarf marmoset Callithrix humilis, was named in 1998 and has since been argued to represent a new genus, Callibella (free pdf here). The Satarè marmoset Mico (Callithrix) saterei, was discovered by van Roosmalen and named by José de Sousa e Silva Júnior and Maurício de Almeida Noronha in 1998 (free pdf here). Two new species of Callithrix, the Manticore marmoset C. manicorensis and Rio Manicoré marmoset C. acariensis were named in 2000 by van Roosmalen and colleagues (free pdf here), and two new titi monkeys, Prince Bernhard’s titi monkey Callicebus bernhardi and Stephen Nash’s titi monkey C. stephennashi [shown in adjacent image], were named by van Roosmalen and colleagues in 2002 (free pdf here).
Marmosets and titi monkeys are one thing. But what if the same worker had also discovered multiple new species of large mammal*? Long-time readers of Tet Zoo will recall my ver 1 post Meet peccary # 4. The 1975 announcement of the discovery of a new living peccary species – the Chacoan peccary Catagonus wagneri – has been hailed as one of the most significant mammalogical discoveries of the 20th century. So the 2004 news that what appears to be another large extant peccary species was really really interesting, to say the least. Van Roosmalen learnt of the new peccary by listening to the local Caboclos people, and was eventually able to observe and photograph the animal in the wild, and later still able to procure material of the species for genetic analysis. The latest news on this species – it is to be formally named the Giant peccary Pecari maximus [it's pictured at left] – is that a full technical paper is in press for Bonner Zoologischen Beiträge (a pdf of the preprint version is available, free, here). Genetic work indicates that this species diverged from its closest living relative, the Collared peccary P. tajacu, about 1.5 million years ago: easily enough time for it to be considered a separate species if, that is, we relied only on some sort of subjective phylogenetic distance measurement as a means of determining status.. which we don’t.
* Given that most mammals weigh less than 1 kg, a ‘large mammal’ could perhaps be regarded as anything bigger than this. The animals I have in mind in this discussion range from a few kg to several 10s of kg.
But now we come to the big news. While the discovery of a new living peccary species is big, this is just the tip of the iceberg. In fact, van Roosmalen has now gathered evidence indicating the presence of a great many new large Amazonian mammals. We are talking several new monkeys, additional new peccaries, new deer, a new tapir, a new dolphin, a new giant anteater, a new big cat… in an effort to bring this new research to wider attention, I’m going to review many of these new species here on the blog, almost the first place they’ve been brought to attention. ‘Almost’? Marc van Roosmalen and I have been corresponding for a while now, and the main reasons for writing this blog post (and the subsequent two or three or four) is to bring Marc’s new website to wider attention. It provides fuller detail on all of the new animals, discusses the other species he has discovered, and also includes links to free pdfs and news articles. Most of this information is entirely new, though summaries and snippets have appeared before. Some of the new animals, though not all of them, were discussed in Karl Shuker’s The New Zoo.
We’ve already seen the Giant peccary. But that’s not all among the ungulates. Scattered here and there in the literature on Marc’s discoveries are references to a new tapir, but because nothing has been forthcoming it’s even been suggested that these mentions might have been confused references to one of the new peccaries. They’re not. Marc really does seem to have a new species of tapir, and has procured a skull that will form the basis of a holotype. Dubbed the anta-pretinho by local people, it is a dwarf tapir endemic to the Rio Aripuanã basin, and is both smaller and far darker in colour than the two recognised Amazonian Tapirus species (Brazilian tapir T. terrestris and Baird’s tapir T. bairdii) [adjacent image shows reconstruction of anta-pretinho].
The new dwarf form also differs from T. terrestris in lacking white tips to its ears (Padilla & Dowler 1994, Emmons 1999); in having proportionally shorter jaws and nasal bones, and in its unique tooth count (it lacks some of the upper premolars and molars, and lower molars, present in all other tapirs). T. terrestris possesses a unique form of sagittal crest (unique both among tapirs, and among mammals in general) where the embryonic crest forms along the dorsal skull roof midline, rather than from two temporal ridges that migrate medially and then coalesce (Holbrook 2002), and it would prove interesting to see whether the dwarf tapir shares this derived pattern of development. In the Rio Aripuanã basin, the new dwarf form is sympatric with T. terrestris: Marc suggests that the latter species has only invaded the basin relatively recently, and that the dwarf taxa is an older endemic.
Of the four named extant tapir species, the Malayan tapir T. indicus wasn’t named until 1819, the Mountain tapir T. pinchaque not until 1829, and Baird’s tapir T. bairdii not until 1865 (it was originally Elasmognathus bairdii Gill, 1865) [adjacent image shows Baird's tapir]. As you’ll know if you’re familiar with Heuvelmans’ On the Track of Unknown Animals, these namings all post-date ‘Cuvier’s rash dictum’: Baron George Cuvier’s 1812 proclamation that no new large land animals remained to be discovered. Actually, loads more extant tapir species have been named more recently than that (including Elasmognathus dowii Gill, 1870, T. spegazzinii Ameghino, 1909 and T. anulipes Hermann, 1924), but all have either been relegated to the status of subspecies, or have been sunk into synonymy. One valid subspecies of T. terrestris, T. t. columbianus, was first named by Hershkovitz (1954). The anta-pretinho, though yet to be formally named and described, will be the first new extant, valid tapir species named since 1865.
More in part II: more peccaries, new brockets, dwarf manatee, dwarf boto, black giant otter and others. Part III will cover lots of new monkeys, and part IV the new giant anteater and the onça-canguçú, a new big cat. Oh yes.
Refs – -
Aggarwal, R. K., Kivisild, T., Ramadevi, J. & Singh, L. 2007. Mitochondrial DNA coding region sequences support the phylogenetic distinction of two Indian wolf species. Journal of Zoological Systematics and Evolutionary Research 45, 163-172.
Collen, B., Purvis, A. & Gittleman, J. L. 2004. Biological correlates of description dates in carnivores and primates. Global Ecology and Biogeography 13, 459-467.
Emmons, L. H. 1999. Neotropical Rainforest Mammals: A Field Guide (Second Edition). University of Chicago Press, Chicago & London.
Hershkovitz, P. 1954. Mammals of northern Colombia. Preliminary report no. 7 tapirs (genus Tapirus), with a systematic review of American species. Proceedings of the United States National Museum 103, 465-496.
Heuvelmans, B. 1983. How many animal species remain to be discovered? Cryptozoology 2, 1-24.
Holbrook, L. T. 2002. The unusual development of the sagittal crest in the Brazilian tapir (Tapirus terrestris). Journal of Zoology 256, 215-219.
Padilla, M. & Dowler, R. C. 1994. Tapirus terrestris. Mammalian Species 481, 1-8.
Patterson, B. D. 2000. Patterns and trends in the discovery of new Neotropical mammals. Diversity and Distributions 6, 145-151.
- . 2001. Fathoming tropical biodiversity: the continuing discovery of Neotropical mammals. Diversity and Distributions 7, 191-196.
- . 2002. On the continuing need for scientific collecting of mammals. Journal of Neotropical Mammalogy 9, 253-262.
Pine, R. H. 1994. New mammals not so seldom. Nature 368, 593.
Voss, R. S. & Da Silva, M. N. F. 2001. Revisionary notes on Neotropical porcupines (Rodentia: Erethizontidae). 2. A review of the Coendou vestitus group with descriptions of two new species from Amazonia. American Museum Novitates 3351, 1-36. | <urn:uuid:6460fb1a-0e85-4758-9a3f-b51c7dba3cd2> | 3.421875 | 2,759 | Personal Blog | Science & Tech. | 54.344709 | 2,195 |
The Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) is a long-term program of scientific research and training dedicated to advancing the understanding of the California Current Large Marine Ecosystem along the U. S. west coast. PISCO conducts monitoring and experiments along 1,200 miles of coastline incorporating oceanography, ecology, chemistry, physiology, molecular biology, genetics, and mathematical modeling to gain novel insights that apply to conservation and resource management issues. The program is led by OSU marine biologist and new head of NOAA, Dr. Jane Lubchenco, and involves scientists at OSU, Stanford, UC Santa Cruz and UC Santa Barbara who lead local, regional, national and international initiatives for marine environmental planning. Since 2005, core funding has been provided by The David and Lucille Packard Foundation and the Gordon and Betty Moore Foundation.
The program focuses on three important ecosystem components: rocky shores, coastal currents, and kelp forests. PISCO’s data on kelp forests are online for the world to see. New interactive maps on the PISCO Web site enable users to explore several years of data on fishes, invertebrates, and algae. Web visitors can select a species and see PISCO’s monitoring data on the species’ abundance, size, and geographic distribution at sites along California’s southern and central coasts. The site includes photos, video, and description of the research methods. The maps are linked directly to the PISCO database, so they automatically display the most up-to-date information. | <urn:uuid:fb516e74-d1d5-4d64-a6e9-037b2c10cc5c> | 2.796875 | 318 | About (Org.) | Science & Tech. | 23.03091 | 2,196 |
Thunderstorms occur frequently during the months of June to November. This is because this is the period referred to as the Hurricane Season, where major flooding and disasters occur to homes, businesses, buildings, infrastructure and livestock.
A thunderstorm is defined by the Merriam Webster Dictionary as “a storm accompanied by lightning and thunder.” Such a storm can be very severe. When it reaches this state of severity, thunderstorms usually have hail, very gustily winds and tornados.
For a thunderstorm to form it requires moisture, rising air which is unstable and a lifting mechanism. The first stage of a thunderstorm is observed by a cumulus cloud being pushed up by rising air. The tipping point is observed when the rising air continues to feed the storm and then precipitation is released and rain begins. These storms may have black or dark green color in appearance.
There are four types of thunderstorms and they are as follows:
A single cell thunderstorm- Such a storm is defined as “an air mass that contains up and down drafts in connective loops, moves and reacts as a single entity, and functions as the smallest unit of a storm-producing system.” This type of storm usually last around thirty minutes and are not severe. Also, they are different to predict because they occur at random times and locations.
A multicell cluster is defined as “a group of cells moving as one, with each having its own life cycle.” This type of thunderstorm is very common and can produce hail, flash floods and tornados.
A multicell line storm is defined as “a long line of storms with a continuous well-developed gust front.
A super cell is the most organized among the types of thunderstorms. With this type of storm, there is little or no precipitation fall back down, making the storm survive for a long period of time. | <urn:uuid:646a6177-e489-47b6-8c19-a073051af62c> | 4.09375 | 388 | Knowledge Article | Science & Tech. | 48.020226 | 2,197 |
The role of rock fracture in erosion
Shortcut URL: http://serc.carleton.edu/38039
Country: New Zealand
UTM coordinates and datum: 58 G 688907 E, 5000710 S
Climate Setting: Humid
Tectonic setting: Continental Collision Margin
Before rock can be eroded, intact bedrock must be broken into smaller pieces that can be detached from the landscape. This detachment process can occur at the scale of grains, thereby promoting grain-by-grain attrition from a rock surface, or at scales that enable landslides. In all cases, fractures serve to decrease overall rock strength by reducing cohesion and potentially by lessening the effective angle of internal friction (Terzaghi, 1962). The creation of fractures results from two major classes of processes: geomorphic and tectonic. Geomorphic processes encompass the broad suite of physical, chemical, and biotic processes that serve to break down rock masses. In almost all cases, these processes are most intense at the surface, and they diminish in effectiveness with depth, typically in some poorly known manner (Fig. 1). Tectonic fracturing results from myriad stresses within tectonic plates, but in actively deforming landscapes, the most likely cause of fracturing is the transport of rocks above irregular fault surfaces. Any kink or change in dip of a fault surface causes a concentration of stresses in the rocks of the hangingwall as they are moved and folded above it (Molnar et al., 2007). The spatial cloud of aftershocks that follows coseismic slip along a fault plane testifies to the dispersed fracturing that commonly occurs as accumulated stress is released in the hangingwall.
Whereas recognition of these fracturing processes and their importance is not new, quantification of their magnitude has been a persistent challenge. How deep is the geomorphically fractured layer? How does fracture density vary with depth or with rock type? Within any mountain range, how diverse is the degree of tectonic fracturing? How does the degree of fracturing (or lack thereof) influence erosion processes? Our inability to see into the shallow subsurface restricts our insights on these questions.
In the early 1980s, the Japanese geomorphologist Suzuki (1982) proposed that seismic velocities could be used as a proxy for local rock strength. More recently, new insights on fracturing of the upper 10 to 20 meters of the rock column have been derived from backpack-able portable seismic arrays (Fig. 2). First, strings of geophones are evenly spaced in 1- to 5-m intervals along linear arrays that stretch for 30 to 60 meters across bedrock surfaces. These arrays are then used to record the first arrival times and the velocity of compressional seismic waves (p-waves) that are created by hitting a strike plate with a sledge hammer at one end of the string of geophones.
In comparison to the velocity of compressional waves in intact bedrock, such as velocities measured on solid rock samples in a lab, the reduction of p-wave velocities in the subsurface of field sites can be attributed to fracturing that impedes transmission of seismic waves. Time-distance plots of the first p-wave arrivals at each geophone can, therefore, reveal key aspects of the pattern of subsurface fracturing. When fracture densities are uniform with depth (consistent with tectonic fracturing), time-distance plots of p-wave arrivals are linear and velocity is uniform with depth (Fig. 3A). In contrast, fracture densities that are greater near the surface and decrease with depth (consistent with geomorphic fracturing), produce slow seismic velocities at that surface that increase with depth. This gradient in velocity results in first p-wave arrivals in time-distance plots that define a curved line (Fig. 3B).
Recent studies on the South Island of New Zealand (Clarke and Burbank, in review) reveal both linear and curved p-wave time-distance plots that correspond with tectonic and geomorphic fracturing models, respectively. Most sites show two layers: an upper geomorphically fractured layer overlying a uniformly fractured lower layer (Fig. 3C). In New Zealand's Fiordland, the base of this geomorphic zone ranges from 2 to 16 meters, but averages 7 meters (Fig. 4). Where this geomorphically fractured layer is absent, apparently due to its removal by erosive processes, the fracture density is nearly uniform with depth and is attributed to tectonic fracturing. A provocative feature of these data is that the geomorphically fractured upper layer tends to be present only when the rock beneath it has been only weakly fractured by tectonic processes. Where tectonic fracturing is more intense (Fig. 4), geomorphic fracturing is commonly not seen. Such highly fractured rocks are interpreted to be sufficiently weak that they fail by bedrock landslides with such frequency that development of a geomorphically fractured layer at the surface is inhibited.
These observations underpin a simple conceptual model (Fig. 5) in which geomorphic fracturing propagates downward into a rock column through time, thereby increasing fracture density and reducing rock strength. Such fracturing should affect the erosional efficacy of many surface processes. In sites where landsliding is a major contributor to overall denudation, this fracturing can weaken formerly strong bedrock to the point of failure, such that most landslides are shallow and occur within this geomorphically weakened zone. In contrast, where the underlying bedrock has already been considerably weakened by pervasive tectonic fracturing, landslides of any depth can occur, and the formation of a highly fractured, geomorphic surface layer is uncommon.
- Clarke, B., and Burbank, D.W., in review, Quantifying bedrock fracture density in the shallow subsurface: Implications for bedrock landslides and erodability: Journal of Geophysical Research.
- Molnar, P., Anderson, R. S., and Anderson, S. P., 2007, Tectonics, fracturing of rock, and erosion: Journal of Geophysical Research, v. 112, p. F03014, doi:10.1029/2005JF000433.
- Suzuki, T., 1982, Rate of lateral planation by Iwaki River, Japan: Transactions of the Japanese Geomorphological Union, v. 3, p. 1-24.
- Terzaghi, 1962, Stability of steep slopes on hard unweathered rock: Geotechnique, no. 12, p. 51-270. | <urn:uuid:292dfa76-6ce4-4c4d-a46f-0907622fb3a2> | 3.625 | 1,330 | Academic Writing | Science & Tech. | 40.361204 | 2,198 |
The primary mission of the Lunar Crater Observation and Sensing Satellite (LCROSS) was a search for lunar water; according to the mission website:
The Mission Objectives of the Lunar Crater Observation and Sensing Satellite (LCROSS) include confirming the presence or absence of water ice in a permanently shadowed crater at the Moon’s South Pole. The identification of water is very important to the future of human activities on the Moon. LCROSS will excavate the permanently dark floor of one of the Moon’s polar craters with two heavy impactors in 2009 to test the theory that ancient ice lies buried there. The impact will eject material from the crater’s surface to create a plume that specialized instruments will be able to analyze for the presence of water (ice and vapor), hydrocarbons and hydrated materials.
LCROSS was successfully launched on June 18 and consisted of two components: the Shepherding Spacecraft and the Centaur rocket. The Lunar Reconnaissance Orbiter (LRO) was launched at the same time, but with a different mission: while the whole purpose of LCROSS was to ultimately crash into the lunar surface on October 9, the LRO is engaged in a year-long mission of observation that included assisting the LCROSS in picking a target crater — Cabeus Crater — at the Moon’s south pole.
LCROSS reached the conclusion of its mission at 7:31 a.m. ET today; now scientists will analyze the data from the impact to learn more about the presence of water on the Moon. As theUSA Today reports,
"I guess my summary is 'really cool'," said Pete Worden of NASA's Ames Research Center in Moffett Field, Calif., which ran the mission. "Today, we kicked up some moon dust and all indications are we are going to have some really interesting results."
Aimed at determining whether the moon contains ice deposits in its shadowed polar craters, the $79 million mission's booster landed at 7:31 a.m. ET, kicking up a moon dust plume.
The mission's "shepherd" spacecraft passed through the plume, observing its chemistry, and then hit the left wall of the crater at 7:35 a.m. ET., kicking up its own plume. Earth observatories and spacecraft observed both impacts.
While the mission was a success, in that the impact was successfully recorded so that the data may be studied, it was not the telegenic success story for which some news outlets, and NASA, had been hoping. According to National Geographic:
NASA's much anticipated LCROSS mission sent two spacecraft "bombing" into the moon early this morning. The craft successfully struck their target, a crater thought to harbor frozen water.
But the much-hyped moon show that had been expected to accompany the impact, however, turned out to be a flop—no billowing plumes of dust and ice visible through backyard telescopes or on NASA TV. The low-impact impact had one NASA expert musing that LCROSS may have struck a "dry hole."
For a generation raised on Hollywood pyrotechnics and computer-generated special effects, the "real thing" may not seem very impressive, visually-speaking, when it comes to an explosion on the Moon. But the science facts that will be revealed in the data are very exciting. Regardless of whether or not LCROSS struck a “dry hole,” the mission was a scientific success. The presence or absence of water on the Moon is of critical significance to any plan for future manned exploration of the lunar surface. If the LCROSS data reveal the presence of water, potential sources of ice will be of tremendous interest to the future of the manned space program, and would be a significant factor in any future plans for a lunar base. | <urn:uuid:508412ab-cf01-4e34-8653-b9c65cbdefe7> | 3.640625 | 800 | News Article | Science & Tech. | 46.760018 | 2,199 |