December 28, 2006, 9:38 PM CT

Carbon Dioxide Emissions Andt Atmosphere

Carbon dioxide emissions from the burning of fossil fuels will produce a 3 percent reduction in the density of Earth's outermost atmosphere by 2017, according to a team of scientists from the National Center for Atmospheric Research (NCAR) and Pennsylvania State University (PSU).

The research appears in the latest issue of the journal Geophysical Research Letters, and will be presented today at the American Geophysical Union conference in San Francisco, Calif.

"We're seeing climate change manifest itself in the upper as well as lower atmosphere," said NCAR scientist Stan Solomon, a co-author of the study. "This shows the far-ranging impacts of greenhouse gas emissions".

Lower density inthe thermosphere, which is the highest layer of the atmosphere, would reduce the drag on satellites in low Earth orbit, allowing them to stay airborne longer. Forecasts of upper-level air density could help NASA and other agencies plan the fuel needs and timing of satellite launches more precisely, potentially saving millions of dollars.

-----Confirming a prediction-----.

Recent observations by scientists tracking satellite orbits have shown that the thermosphere, which begins about 60 miles above Earth and extends up to 400 miles, is beginning to become less dense, said Robert Kerr, program director in the National Science Foundation's (NSF) Division of Atmospheric Sciences.........

Posted by: Beverly      Read more         Source

December 28, 2006, 9:31 PM CT

What Killed and Preserved Juvenile Fossil Plesiosaur

Amid 70-mile-an-hour winds and freezing Antarctic conditions, an American-Argentine research team has recovered the well-preserved fossil skeleton of a juvenile plesiosaur--a marine reptile that swam the waters of the Southern Ocean roughly 70 million years ago.

The fossil remains represent one of the most-complete plesiosaur skeletons ever found and is believed to be the best-articulated fossil skeleton ever recovered from Antarctica. The creature would have inhabited Antarctic waters during a period when the Earth and oceans were far warmer than they are today.

James E. Martin, curator of vertebrate paleontology and coordinator of the paleontology program at the South Dakota School of Mines and Technology's Museum of Geology, announced recently the plesiosaur bones will be unveiled at the museum on Dec.13, 2006.

The long-necked, diamond-finned plesiosaurs are probably most familiar as the legendary inhabitants of Scotland's Loch Ness, eventhough scientific evidence indicates the marine carnivores have been extinct for millions of years. But when the creatures were alive, their paddle-like fins would have allowed them to "fly through the water" in a motion very similar to modern-day penguins.

Martin, an expert on fossil marine reptiles, co-led the 2005 expedition to Antarctica that recovered the plesiosaur. Judd Case, of Eastern Washington University, and Marcelo Reguero of the Museo de La Plata, Argentina, were also co- leaders.........

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December 28, 2006, 8:45 PM CT

As Kisspeptin Levels Plummet

A hormone implicated in the onset of human puberty also appears to control reproductive activity in seasonally breeding rodents, report Indiana University Bloomington and University of California at Berkeley scientists in the March 2007 issue of Endocrinology. The paper is now accessible online via the journal's rapid electronic publication service.

The researchers present evidence that kisspeptin, a recently discovered neuropeptide encoded by the KiSS-1 gene, mediates the decline of male Siberian hamsters' libido and reproduction as winter approaches and daylight hours wane.

"Ours isn't the first study to link the peptide to reproduction, but it is the first to connect kisspeptin to how animals interpret seasonal cues, including day length," said IUB biologist Gregory Demas. "Kisspeptin likely plays an integral role in coordinating seasonal reproduction in a wide range of animals".

Kisspeptin joins a select few proteins believed to act as switches that connect environmental changes to a physiological response.

"This peptide is poised to act as an integrator of environmental information to allow for the optimal neuroendocrine control of reproduction in vertebrates, including humans," said UC Berkeley neuroscientist Lance Kriegsfeld. "In humans and other species, if the environment is not satisfactory, sex drive will decline; kisspeptin is likely part of the pathway responsible for this regulation".........

Posted by: Beverly      Read more         Source

December 28, 2006, 8:32 PM CT

Where to get Dust for Brazilian rainfores

More than half of the dust needed for fertilizing the Brazilian rainforest is supplied by a valley in northern Chad, according to an international research team headed by Dr. Ilan Koren of the Institute's Environmental Sciences and Energy Research Department. According to a research findings published recently in Environmental Research Letters, the scientists have explained how the Bodele valley's unique features might be responsible for making it such a major dust provider.

It has been known for more than a decade that the existence of the Amazon rainforest depends on a supply of minerals washed off by rain from the soil in the Sahara and blown across the Atlantic by dust. By combining various types of satellite data, Dr. Koren and colleagues from Israel, the United Kingdom, the United States, and Brazil have now for the first time managed to obtain quantitative information about the weight of this dust. Analyses of dust quantities were performed near the Bodele valley itself, on the shore of the Atlantic and at an additional spot above the ocean.

The data revealed that some 56 percent of the dust reaching the Amazon forest originates in the Bodele valley. They also showed that a total of some 50 million tons of dust make their way from Africa to the Amazon region every year, a much higher figure than the previous estimates of 13 million tons. The new estimate matches the calculations on the quantity of dust needed to supply the vital minerals for the continued existence of the Amazon rainforest.........

Posted by: Beverly      Read more         Source

December 27, 2006, 5:06 AM CT

Mixed Prairie Grasses Better Source Of Biofuel

Diverse mixtures of native prairie plant species have emerged as a leader in the quest to identify the best source of biomass for producing sustainable, bio-based fuel to replace petroleum.

A new study led by David Tilman, an ecologist at the University of Minnesota, shows that mixtures of native perennial grasses and other flowering plants provide more usable energy per acre than corn grain ethanol or soybean biodiesel and are far better for the environment. The research was supported by the National Science Foundation (NSF) and the University of Minnesota Initiative for Renewable Energy and the Environment.

"Biofuels made from high-diversity mixtures of prairie plants can reduce global warming by removing carbon dioxide from the atmosphere. Even when grown on infertile soils, they can provide a substantial portion of global energy needs, and leave fertile land for food production," Tilman said.

The findings are reported in the Dec. 8, 2006, issue of the journal Science.

The is study based on 10 years of research at Minnesota's Cedar Creek Natural History Area, one of 26 NSF long-term ecological research (LTER) sites. It shows that degraded agricultural land planted with diverse mixtures of prairie grasses and other flowering plants produces 238 percent more bioenergy on average than the same land planted with various single prairie plant species, including switchgrass.........

Posted by: Beverly      Read more         Source

December 26, 2006, 6:32 PM CT

Developing Invisibility

The theorists who first created the mathematics that describe the behavior of the recently announced "invisibility cloak" have revealed a new analysis that may extend the current cloak's powers, enabling it to hide even actively radiating objects like a flashlight or cell phone.

Allan Greenleaf, professor of mathematics at the University of Rochester, working with colleagues around the globe, has announced a mathematical theory that predicts some strange goings on inside the cloak-and that what happens inside is crucial to the cloak's effectiveness.

In October, David R. Smith, associate professor of electrical and computer engineering at Duke University, led a team that used a circular cloaking device to successfully bend microwaves around a copper disk as if the disk were invisible. In 2003, however, Greenleaf and colleagues had already developed the mathematics of invisibility.

"We were working on improving the mathematics behind tumor detection," says Greenleaf. "In the final section to one paper, we spelled out a worst-case scenario where a tumor could be undetectable. We then wrote a couple of additional articles describing when this could happen. At the time, we didn't think further about it because it seemed extremely unlikely that any tumor would be covered with the necessary material to be hidden that way".........

Posted by: Beverly      Read more         Source

December 26, 2006, 6:00 PM CT

How Does A Zebrafish Grow A New Tail?

This interesting article I was reading today illustrates how amazingly zebra fish regains its tail after losing one. Apparently a zebrafish tail grows back within a matter of one week. It not only can replace the tail, but also can replace many other body parts. Amazing!

A tail fin, for example, has many different types of cells and is a very intricate structure. It is the fish version of an arm or leg.

The question of how cold-blooded animals re-grow missing tails and other appendages has fascinated veterinary and medical scientists. They also wonder if people, and other warm-blooded animals that evolved from these simpler creatures, might still have untapped regenerative powers hidden in their genes.

People are constantly renewing blood components, skeletal muscles and skin. We can regenerate liver tissue and repair minor injuries to bone, muscle, the tips of our toes and fingers, and the corneas of our eyes. Finding out more about the remarkable ability of amphibians and fish to re-grow complex parts might provide the information necessary to create treatments for people whose hearts, spinal cords, eyes or arms and legs have been badly hurt.

Scientists have discovered some of the genes and cell-to-cell communication pathways that enable zebrafish to restore their tail fins.........

Posted by: Beverly      Read more         Source

December 25, 2006, 4:29 PM CT

Ocean Temperature And Marine Species

Ocean temperature apparently has a great effect on the spread of marine species. I was reading the following article this morning, and thought about writing this article in this column.

Scientists can predict how the distance marine larvae travel varies with ocean temperature - a key component in conservation and management of fish, shellfish and other marine species - according to a new study from the University of North Carolina at Chapel Hill.

Most marine life, including commercially important species, reproduces via larvae that drift far along ocean currents before returning to join adult populations. The distance larvae travel before maturing, called dispersal, is directly linked to ocean temperature, the researchers found. For example, larvae from the same species travel far less in warmer waters than in colder waters, said lead author Mary O'Connor, a graduate student in marine ecology in UNC's curriculum in ecology and the department of marine sciences in the College of Arts and Sciences.

"Temperature can alter the number and diversity of adult species in a certain area by changing where larvae end up," O'Connor said. "It is important to understand how a fish population is replenished if we want to attempt to manage or conserve it".

Using data from 72 marine species, including cod, herring, American lobster, horseshoe crabs and clams, O'Connor and her colleagues developed a model that predicts how far larvae travel at a certain temperature. The predictions appear to hold for virtually all marine animals with a larval life cycle.........

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December 23, 2006, 9:01 AM CT

Giraffe: Winning by a neck

Whenever I go to a zoo, I stand in front of the giraffes and watch with awe and respect at these wonderful creatures. I always consider them to be an extreme example of natural selection. I read this article and thought it would be worth mentioning in our blog.

The giraffe's elongated neck has long been used in textbooks as an illustration of evolution by natural selection, but this common example has received very little experimental attention. In the recent issue of the American Naturalist, researchers at the Mammal Research Institute in the Department of Zoology and Entomology at the University of Pretoria tested whether foraging competition with shorter herbivores could explain why giraffes feed mostly on leaves high in trees, despite being able to feed at lower levels as well.

"This [study] provides the first real experimental evidence that the long neck of the giraffe might have evolved as a consequence of competition, which provides support for a previously untested textbook example of natural selection," says Elissa Cameron (University of Pretoria), who coauthored the study with Johan du Toit (University of Pretoria and Utah State University).

Giraffes are well known for their unusual height, and they generally feed high in the tree canopy, above the height other herbivores can reach. Giraffes receive more leaves per bite by foraging high in the tree, but it's unclear whether this is caused by competition -- smaller browsers eating some of the leaves at lower heights -- or if more leaves grow at higher levels.........

Posted by: Kelly      Read more         Source

December 20, 2006, 4:17 AM CT

Language of the Nerve Cells

UC San Diego biologists have shown that the chemical language with which neurons communicate depends on the pattern of electrical activity in the developing nervous system. The findings suggest that modification of nerve activity could have potential as a therapy for a wide range of brain disorders.

In the study, published this week in the early on-line edition of the journal Proceedings of the National Academy of Sciences, the biologists showed that, contrary to the prevailing viewpoint, neurotransmitters-the chemical language of nerve cells-and receptors-the proteins that receive and respond to neurotransmitters-are not specified by a rigid genetic program. Altering nerve activity during development determines the "mother tongue" nerve cells use to communicate. The study will appear in the print edition of PNAS on January 2.

"Most cognitive disorders, such as depression, schizophrenia and Parkinson's disease, involve problems with neurotransmitters or neurotransmitter receptors," said Nicholas Spitzer, a professor of biology and the senior author of the study. "If modifying electrical activity in the adult brain can alter neurotransmitters and receptors similarly to the way we have discovered in the developing frog nervous system, it could provide a promising approach to treating these disorders".........

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