The coupled normal mode method is a powerful approach for solving range-dependent propagation problems in underwater acoustics. An important area of study is to improve stability and efficiency so as to be able to deal with complex scenarios in a realistic environment. Professor LUO Wenyu and his group from the State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, set out to tackle this problem.
Earth
AMES, Iowa – Christopher Karstens was on the ground studying the damage caused by the deadly April 27, 2011, tornado that hit Tuscaloosa and Birmingham, Ala.
It was just a week after the tornado. He was between the two cities, in the rough country of the southern Appalachians about 20 miles northeast of Tuscaloosa. He said it's terrain that's "beyond hilly." It's covered by dense forest and clogged by high brush that's tough to walk through. A hike of about 100 yards sometimes took as long as 45 minutes.
Boston, MA – New research from Harvard School of Public Health (HSPH) suggests that seemingly small changes in summer temperature swings—as little as 1°C more than usual—may shorten life expectancy for elderly people with chronic medical conditions, and could result in thousands of additional deaths each year. While previous studies have focused on the short-term effects of heat waves, this is the first study to examine the longer-term effects of climate change on life expectancy.
CORVALLIS, Ore. – A survey done on the loss in the Northern Hemisphere of large predators, particularly wolves, concludes that current populations of moose, deer, and other large herbivores far exceed their historic levels and are contributing to disrupted ecosystems.
The research, published today by scientists from Oregon State University, examined 42 studies done over the past 50 years.
Daejeon, the Republic of Korea, April 9, 2012—The Korea Advanced Institute of Science and Technology (KAIST) announced that a research team from the Department of Materials Science and Engineering has developed a technology that enables scientists and engineers to observe processes occurring in liquid media on the smallest possible scale which is less than a nanometer.
CORVALLIS, Ore. – An analysis of 35 headwater basins in the United States and Canada found that the impact of warmer air temperatures on streamflow rates was less than expected in many locations, suggesting that some ecosystems may be resilient to certain aspects of climate change.
The study was just published in a special issue of the journal BioScience, in which the Long-Term Ecological Research (LTER) network of 26 sites around the country funded by the National Science Foundation is featured.
Ecosystems are changing worldwide as a result of shrinking sea ice, snow, and glaciers, especially in high-latitude regions where water is frozen for at least a month each year—the cryosphere. Scientists have already recorded how some larger animals, such as penguins and polar bears, are responding to loss of their habitat, but research is only now starting to uncover less-obvious effects of the shrinking cryosphere on organisms.
WASHINGTON, D.C., APRIL 6, 2012—As global temperatures rise, the most threatened ecosystems are those that depend on a season of snow and ice, scientists from the nation's Long Term Ecological Research (LTER) Network say."The vulnerability of cool, wet areas to climate change is striking," says Julia Jones, a lead author in a special issue of the journal BioScience released today featuring results from more than 30 years of LTER, a program of the National Science Foundation (NSF).
When most people look at a forest, they see walking trails, deer yards, or firewood for next winter. But scientists at the Harvard Forest and Smithsonian Institution take note of changes imperceptible to the naked eye -- the uptake and storage of carbon. What they've learned in a recent study is that an immense amount of carbon is stored in growing trees, but if current trends in Massachusetts continue, development would reduce that storage by 18 percent over the next half century. Forest harvesting would have a much smaller impact.
Earth is clingy when it comes to copper. A new Rice University study this week in the journal Science finds that nature conspires at scales both large and small -- from the realms of tectonic plates down to molecular bonds -- to keep most of Earth's copper buried dozens of miles below ground.
Scientists at the Cavendish Laboratory in Cambridge have used light to help push electrons through a classically impenetrable barrier. While quantum tunnelling is at the heart of the peculiar wave nature of particles, this is the first time that it has been controlled by light. Their research is published today, 05 April, in the journal Science.
New England is expected to experience a "moderate" regional "red tide" this spring and summer, report NOAA-funded scientists working in the Gulf of Maine to study the toxic algae that causes the bloom. The algae in the water pose no direct threat to human beings, however the toxins they produce can accumulate in filter-feeding organisms such as mussels and clams— which can cause paralytic shellfish poisoning (PSP) in humans who consume them.
EAST LANSING, Mich. — American students need a dramatically new approach to improve how they learn science, says a noted group of scientists and educators led by Michigan State University professor William Schmidt.
One of the satellite's first observations following its launch on 1 March 2002 was of break-up of a main section of the Larsen B ice shelf in Antarctica – when 3200 sq km of ice disintegrated within a few days due to mechanical instabilities of the ice masses triggered by climate warming.
Now, with ten years of observations using its Advanced Synthetic Aperture Radar (ASAR), Envisat has mapped an additional loss in Larsen B's area of 1790 sq km over the past decade.
Harvard scientists are helping to paint the fullest picture yet of how a handful of factors, particularly world-wide increases in atmospheric carbon dioxide, combined to end the last ice age approximately 20,000 to 10,000 years ago.
As described in a paper published April 5 in Nature, researchers compiled ice and sedimentary core samples collected from dozens of locations around the world, and found evidence that while changes in Earth's orbit may have touched off a warming trend, increases in CO2 played a far more important role in pushing the planet out of the ice age.