Scientists build new ‘tree of life’ for placentals, visualize common ancestor
Scientists have reconstructed the common ancestor of placental mammals–an extremely diverse group including animals ranging from rodents to whales to humans–using the world’s largest dataset of both genetic and physical traits. (more…)
Microbe-eating flies from at least three different locations around the world recently have evolved into herbivores, feeding on some of the most toxic plants on Earth. Fly detectives and UA evolutionary biologists Noah Whiteman and Richard Lapoint are trying to find out what genetic pathways led the flies to such a major change of lifestyle.
For millennia, they buzzed through the woods, contentedly munching yeasts off the surfaces of leaves, bracken and rotting duff on the forest floor. But now, flies in the family Drosophilidae, whose disparate members dwell in areas all across the planet, have evolved into all-out vegetarians with a wicked diet of plants that are deadly to most other organisms.
What, University of Arizona scientists would like to know, has caused these flies, yeast-feeders for nearly 80 million years, to independently go cold turkey with respect to their formerly meaty diets? (more…)
Berkeley Lab scientists devise new tools for detecting previously unknown tree mortality.
The Earth’s forests perform a well-known service to the planet, absorbing a great deal of the carbon dioxide pollution emitted into the atmosphere from human activities. But when trees are killed by natural disturbances, such as fire, drought or wind, their decay also releases carbon back into the atmosphere, making it critical to quantify tree mortality in order to understand the role of forests in the global climate system. Tropical old-growth forests may play a large role in this absorption service, yet tree mortality patterns for these forests are not well understood.
Now scientist Jeffrey Chambers and colleagues at the U.S. Department of Energy’s (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) have devised an analytical method that combines satellite images, simulation modeling and painstaking fieldwork to help researchers detect forest mortality patterns and trends. This new tool will enhance understanding of the role of forests in carbon sequestration and the impact of climate change on such disturbances. (more…)
PASADENA, Calif. — Researchers using NASA’s Mars Reconnaissance Orbiter see seasonal changes on far-northern Martian sand dunes caused by warming of a winter blanket of frozen carbon dioxide.
Earth has no naturally frozen carbon dioxide, though pieces of manufactured carbon-dioxide ice, called “dry ice,” sublime directly from solid to gas on Earth, just as the vast blankets of dry ice do on Mars. A driving factor in the springtime changes where seasonal coverings of dry ice form on Mars is that thawing occurs at the underside of the ice sheet, where it is in contact with dark ground being warmed by early-spring sunshine through translucent ice. The trapped gas builds up pressure and breaks out in various ways. (more…)
Better science communication could lead to a more informed American public.
Public acceptance of climate change’s reality may have been influenced by the rate at which words moved from scientific journals into the mainstream, according to anthropologist Michael O’Brien, dean of the College of Arts and Science at the University of Missouri. A recent study of word usage in popular literature by O’Brien and his colleagues documented how the usage of certain words related to climate change has risen and fallen over the past two centuries. Understanding how word usage affects public acceptance of science could lead to better science communication and a more informed public.
“Scientists can learn from this study that the general public shouldn’t be expected to understand technical terms or be convinced by journal papers written in technical jargon,” O’Brien said. “Journalists must explain scientific terms in ways people can understand and thereby ease the movement of those terms into general speech. That can be a slow process. Several words related to climate change diffused into the popular vocabulary over a 30-50 year timeline.” (more…)
PASADENA, Calif. – An area of the Amazon rainforest twice the size of California continues to suffer from the effects of a megadrought that began in 2005, finds a new NASA-led study. These results, together with observed recurrences of droughts every few years and associated damage to the forests in southern and western Amazonia in the past decade, suggest these rainforests may be showing the first signs of potential large-scale degradation due to climate change.
An international research team led by Sassan Saatchi of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., analyzed more than a decade of satellite microwave radar data collected between 2000 and 2009 over Amazonia. The observations included measurements of rainfall from NASA’s Tropical Rainfall Measuring Mission and measurements of the moisture content and structure of the forest canopy (top layer) from the Seawinds scatterometer on NASA’s QuikScat spacecraft. (more…)
Why are efficient and affordable solar cells so highly coveted? Volume. The amount of solar energy lighting up Earth’s land mass every year is nearly 3,000 times the total amount of annual human energy use. But to compete with energy from fossil fuels, photovoltaic devices must convert sunlight to electricity with a certain measure of efficiency. For polymer-based organic photovoltaic cells, which are far less expensive to manufacture than silicon-based solar cells, scientists have long believed that the key to high efficiencies rests in the purity of the polymer/organic cell’s two domains – acceptor and donor. Now, however, an alternate and possibly easier route forward has been shown.
Working at Berkeley Lab’s Advanced Light Source (ALS), a premier source of X-ray and ultraviolet light beams for research, an international team of scientists found that for highly efficient polymer/organic photovoltaic cells, size matters. (more…)
Study simulating pressures in mantle beneath the ocean floor shows that rocks can melt at depths up to 250 kilometers
Magma forms far deeper than geologists previously thought, according to new research results.
A team led by geologist Rajdeep Dasgupta of Rice University put very small samples of peridotite, rock derived from Earth’s mantle, under high pressures in a laboratory.
The scientists found that the rock can and does liquify, at least in small amounts, at pressures equivalent to those found as deep as 250 kilometers down in the mantle beneath the ocean floor. (more…)
