Tuesday 5 June 2012
Some Butterfly Species Particularly Vulnerable to Climate Change
Southern Gatekeeper. (Credit: Image courtesy of Oregon State University)
ScienceDaily (June 1, 2012) — A recent study of the impact of climate change on butterflies suggests that some species might adapt much better than others, with implications for the pollination and herbivory associated with these and other insect species.
The research, published in Ecological Entomology, examined changes in the life cycles of butterflies at different elevations of a mountain range in central Spain. They served as a model for some of the changes expected to come with warming temperatures, particularly in mountain landscapes.
The researchers found that butterfly species which already tend to emerge later in the year or fly higher in the mountains have evolved to deal with a shorter window of opportunity to reproduce, and as a result may fare worse in a warming climate, compared to those that emerge over a longer time period.
"Insects and plants are at the base of the food pyramid and are extremely important, but they often get less attention when we are studying the ecological impacts of climate change," said Javier G. Illan, with the Department of Forest Ecosystems and Society at Oregon State University.
"We're already expecting localized extinctions of about one third of butterfly species, so we need to understand how climate change will affect those that survive," he said. "This research makes it clear that some will do a lot better than others."
Butterflies may be particularly sensitive to a changing climate, Illan said, and make a good model to study the broader range of ecological effects linked to insects. Their flight dates are a relevant indicator of future responses to climate change.
The research was done by Illan's group in the Rey Juan Carlos University in Madrid. It examined 32 butterfly species for five years at various elevations in a Mediterranean mountain range, and the delays in flight dates that occurred as a result of elevation change
The Mysterious Arc of Venus
Three photos from the Arc of Venus observed during the planet's 2004 transit by amateur astronomer near Toulouse, France. (Credit: Image Courtesy of André Rondi)
ScienceDaily (June 4, 2012) — When Venus transits the sun on June 5th and 6th, an armada of spacecraft and ground-based telescopes will be on the lookout for something elusive and, until recently, unexpected: The Arc of Venus.
"I was flabbergasted when I first saw it during the 2004 transit," recalls astronomy professor Jay Pasachoff of Williams College. "A bright, glowing rim appeared around the edge of Venus soon after it began to move into the sun."
For a brief instant, the planet had turned into a "ring of fire."
Researchers now understand what happened. Backlit by the sun, Venus's atmosphere refracted sunlight passing through layers of air above the planet's cloudtops, creating an arc of light that was visible in backyard telescopes and spacecraft alike.
It turns out, researchers can learn a lot about Venus by observing the arc. Indeed, it touches on some of the deepest mysteries of the second planet.
› View larger The arc of Venus photographed in 2004 by Riccardo Robitschek and Giovanni Maria Caglieris of Milan, Italy. "We do not understand why our sister planet's atmosphere evolved to be so different than Earth's," explains planetary scientist Thomas Widemann of the Observatoire de Paris.
Earth and Venus are similar distances from the sun, are made of the same basic materials, and are almost perfect twins in terms of size. Yet the two planets are wrapped in stunningly dissimilar blankets of air. Venus's atmosphere is almost 100 times more massive than Earth's and consists mainly of CO2, a greenhouse gas that raises the surface temperature to almost 900°F. Clouds of sulfuric acid tower 14 miles high and whip around the planet as fast as 220 mph. A human being transported to this hellish environment would be crushed, suffocate, desiccate, and possibly ignite.
For the most part, planetary scientists have no idea how Venus turned out this way.
"Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet," points out Widemann. "Caring about Venus is caring about ourselves."
One of the biggest mysteries of Venus is super-rotation. The whole atmosphere circles the planet in just four Earth days, much faster than the planet's spin period of 243 days. "The dynamics of super-rotation are still a puzzle despite a wealth of data from landmark missions such as NASA's Pioneer Venus, Russia's Venera and VEGA missions, NASA's Magellan and more recently ESA's Venus Express."
The arc of Venus as seen by NASA's TRACE spacecraft in 2004. Credit: NASA/Trace/LMSAL This is where the Arc of Venus comes in. The brightness of the arc reveals the temperature and density structure of Venus's middle atmosphere, or "mesosphere," where the sunlight is refracted. According to some models, the mesosphere is key to the physics of super-rotation. By analyzing the lightcurve of the arc, researchers can figure out the temperature and density of this critical layer from pole to pole.
When the arc appeared in 2004, the apparition took astronomers by surprise; as a result, their observations were not optimized to capture and analyze the fast-changing ring of light.
This time, however, they are ready. Together, Pasachoff and Widemann have organized a worldwide effort to monitor the phenomenon on June 5th, 2012. "We're going to observe the arc using 9 coronagraphs spaced around the world," says Pasachoff. "Observing sites include Haleakala, Big Bear, and Sacramento Peak. Japan's Hinode spacecraft and NASA's Solar Dynamics Observatory will also be gathering data."
Pasachoff has some advice for amateur astronomers who wish to observe the arc. "The best times to look are ingress and egress--that is, when the disk of Venus is entering and exiting the sun. Ingress is between 22:09 and 22:27 UT on June 5th; egress occurs between 04:32 and 04:50 UT. Be sure your telescope is safely filtered. Both white light and H-alpha filters might possibly show the arc."
Monday 4 June 2012
Mosquitoes Fly in Rain Thanks to Low Mass
ScienceDaily (June 4, 2012) — The mosquito is possibly summer's biggest nuisance. Sprays, pesticides, citronella candles, bug zappers -- nothing seems to totally deter the blood-sucking insect. And neither can rain apparently.
Even though a single raindrop can weigh 50 times more than a mosquito, the insect is still able to fly through a downpour.
Georgia Tech researchers used high-speed videography to determine how this is possible. They found the mosquito's strong exoskeleton and low mass render it impervious to falling raindrops.
The research team, led by Assistant Professor of Mechanical Engineering David Hu and his doctoral student Andrew Dickerson, found that mosquitoes receive low impact forces from raindrops because the mass of mosquitoes causes raindrops to lose little momentum upon impact. The results of the research will appear in the June 4 issue of the Proceedings of the National Academy of Sciences.
"The most surprising part of this project was seeing the robustness this small flyer has in the rain," Dickerson said. "If you were to scale up the impact to human size, we would not survive. It would be like standing in the road and getting hit by a car."
What the researchers learned about mosquito flight could be used to enhance the design and features of micro-airborne vehicles, which are increasingly being used by law enforcement and the military in surveillance and search-and-rescue operations.
To study how mosquitoes fly in the rain, the research team constructed a flight arena consisting of a small acrylic cage covered with mesh to contain the mosquitoes but permit entry of water drops. They used a water jet to simulate rain stream velocity and observed six mosquitoes flying into the stream. All the mosquitoes survived the collision.
"The collision force must equal the resistance applied by the insect," Hu said. "Mosquitoes don't resist at all, but simply go with the flow."
The team also filmed free-flying mosquitoes that were subjected to rain drops. They found that upon impact the mosquito is adhered to the front of the drop for up to 20 body lengths.
"To survive, the mosquito must eventually separate from the front of the drop," Hu said. "The mosquito accomplishes this by using its long legs and wings, whose drag forces act to rotate the mosquito off the point of contact. This is necessary, otherwise the mosquito will be thrown into the ground at the speed of a falling raindrop."
Free-flying mosquitoes can survive the high-speed impact of falling raindrops. High-speed videography of those impacts reveals a mechanism for survival: A mosquito's strong exoskeleton and low mass renders it impervious to falling drops. (Credit: Image courtesy of Georgia Institute of Technology
Catching Solar Particles Infiltrating Earth's Atmosphere
ScienceDaily (May 31, 2012) — On May 17, 2012 an M-class flare exploded from the sun. The eruption also shot out a burst of solar particles traveling at nearly the speed of light that reached Earth about 20 minutes after the light from the flare. An M-class flare is considered a "moderate" flare, at least ten times less powerful than the largest X-class flares, but the particles sent out on May 17 were so fast and energetic that when they collided with atoms in Earth's atmosphere, they caused a shower of particles to cascade down toward Earth's surface. The shower created what's called a ground level enhancement (GLE).
GLEs are quite rare -- fewer than 100 events have been observed in the last 70 years, since instruments were first able to detect them. Moreover, this was the first GLE of the current solar cycle--a sure sign that the sun's regular 11-year cycle is ramping up toward solar maximum.
This GLE has scientists excited for another reason, too. The joint Russian/Italian mission PAMELA, short for Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics, simultaneously measured the particles from the sun that caused the GLE. Solar particles have been measured before, but PAMELA is sensitive to the very high-energy particles that reach ground level at Earth. The data may help scientists understand the details of what causes this space weather phenomenon, and help them tease out why a relatively small flare was capable of producing the high-speed particles needed to cause a GLE.
"Usually we would expect this kind of ground level enhancement from a giant coronal mass ejection or a big X-class flare," says Georgia de Nolfo, a space scientist who studies high speed solar particles at NASA's Goddard Space Flight Center in Greenbelt, Md. "So not only are we really excited that we were able to observe these particularly high energy particles from space, but we also have a scientific puzzle to solve."
The path to this observation began on Saturday, May 5, when a large sunspot rotated into view on the left side of the sun. The sunspot was as big as about 15 Earths, a fairly sizable active region, though by no means as big as some of the largest sunspots that have been observed on the sun. Dubbed Active Region 1476, the sunspots had already shown activity on the back side of the sun -- as seen by a NASA mission called the Solar Terrestrial Relations Observatory (STEREO) -- so scientists were on alert for more. Scientists who study high-energy particles from the sun had been keeping their eye out for just such an active region because they had seen no GLEs since December of 2006.
In addition, they had high hopes that the PAMELA mission, which had focused on cosmic rays from outside our galaxy could now be used to observe solar particles. Such "solar cosmic rays" are the most energetic particles that can be accelerated at or near the sun.
But there was a hitch: the satellite carrying the PAMELA instruments were not currently usable since they were in calibration mode. Scientists including de Nolfo and another Goddard researcher, Eric Christian, let the PAMELA collaboration know that this might be the chance they had been waiting for and they convinced the Russian team in charge of the mission to turn the instruments back on to science mode.
"And then the active region pretty much did nothing for two weeks," says Christian. "But just before it disappeared over the right side of the sun, it finally erupted with an M-class flare."
Bingo. Neutron monitors all over the world detected the shower of neutrons that represent a GLE. Most of the time the showers are not the solar energetic particles themselves, but the resultant debris of super-fast particles slamming into atoms in Earth's atmosphere. The elevated levels of neutrons lasted for an hour.
Simultaneously, PAMELA recorded the incoming solar particles up in space, providing one of the first in-situ measurements of the stream of particles that initiated a GLE. Only the early data has been seen so far, but scientists have high hopes that as more observations are relayed down to Earth, they will be able to learn more about the May 17 onslaught of solar protons, and figure out why this event triggered a GLE when earlier bursts of solar protons in January and March, 2012 didn't.
An artist's concept of the shower of particles produced when Earth's atmosphere is struck by ultra-high-energy cosmic rays. (Credit: Simon Swordy/University of Chicago, NASA)
Producing Artificial Bones from Fish Scales
ScienceDaily (June 1, 2012) — Tokyo Tech's Toshiyuki Ikoma and Junzo Tanaka have developed technology for producing artificial bones from fish scales and apatite.
Toshiyuki Ikoma and Junzo Tanaka have developed technology for producing artificial bones from fish scales and apatite. "Our technology enables the formation of new bone tissues within three months," says Ikoma. "This is much faster than the six months required using collagen from porcine dermis." The use of fish collagen also mitigates the potential infection of humans with viruses from pigs. "This new material is very safe," emphasizes Ikoma.
Other features of artificial bones fabricated by fish collagen and apatite include the finding that:
(1) the bones have a much higher density and are thereby very strong;
(2) the bones implanted into bone defects transform into bone tissue much faster than those using porcine dermis collagen.
"One of our major aims is to use fish collagen for the treatment of bone tumors in older people whose bones take longer to regenerate," explains Ikoma. "Fish collagen is a material that has the potential of becoming the key material for the development of artificial bones and bone therapy.
In addition to the regeneration of bones from fish collagen, the Tanaka and Ikoma Research group is pursuing projects on nanomedicine and diagnostics. Notably, the Tokyo Institute of Technology group conducts research on tissue engineering and implantable biomaterials in collaboration with medical doctors and biologists. "An interdisciplinary approach with researchers from the medical and engineering fields is very crucial for success" says Ikoma.
In the fish collagen experiments, the researchers have focused on type I collagen extracted from tilapia scales because the scale has little fat and is mainly composed of pure collagen. Intriguingly, Tilapia lives in warm fresh water and the scale collagen shows the highest denaturation (the change of collagen to gelatin) temperature at 36oC, and has no fishy odor.
The Tokyo Tech group has transferred the extraction technology of collagen from tilapia scale to a company. "Interestingly, the structure of collagen fibrils in fish scale is very similar to that of human corneal stroma," says Ikoma. "So the investigation of fish scale will be useful for the reconstruction of corneal stroma."
The unique characteristics of fish collagen show potential for the production of cosmetics. "We have already produced cosmetics including the fish collagen," says Ikoma. "Next, we would like to produce the other products such as cell culture substrates, scaffolds for tissue engineering, and implantable biomaterials."
Wind Power
At the end of 2006, worldwide capacity of wind-powered generators was 73.9 gigawatts; although it currently produces just over 1% of world-wide electricity use, it accounts for approximately 20% of electricity use in Denmark, 9% in Spain, and 7% in Germany.Globally, wind power generation more than quadrupled between 2000 and 2006. Most modern wind power is generated in the form of electricity by converting the rotation of turbine blades into electrical current by means of an electrical generator.
In windmills (a much older technology), wind energy is used to turn mechanical machinery to do physical work, such as crushing grain or pumping water. Wind power is used in large scale wind farms for national electrical grids as well as in small individual turbines for providing electricity to rural residences or grid-isolated locations. Wind energy is plentiful, renewable, widely distributed, clean, and reduces toxic atmospheric and greenhouse gas emissions if used to replace fossil-fuel-derived electricity.
The intermittency of wind seldom creates problems when using wind power at low to moderate penetration levels. There are many thousands of wind turbines operating, with a total capacity of 73,904 MW of which Europe accounts for 65% (2006).
The average output of one megawatt of wind power is equivalent to the average electricity consumption of about 250 American households.
Wind power was the most rapidly-growing means of alternative electricity generation at the turn of the century and world wind generation capacity more than quadrupled between 1999 and 2005. There is an estimated 50 to 100 times more wind energy than plant biomass energy available on Earth.
Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) occur.
Eventually, the wind energy is converted through friction into diffuse heat throughout the Earth's surface and the atmosphere. Large-scale onshore and near-shore wind energy facilities (wind farms) can be controversial due to aesthetic reasons and impact on the local environment. It should be noted, however, that onshore and near-shore studies show that the number of birds killed by wind turbines is negligible compared to the number that die as a result of other human activities such as traffic, hunting, power lines and high-rise buildings and especially the environmental impacts of using non-clean power sources.
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