Wednesday, February 23, 2011

Rare insect fossil reveals 100 million years of evolutionary stasis

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Researchers have discovered the 100 million-year-old ancestor of a group of large, carnivorous, cricket-like insects that still live today in southern Asia, northern Indochina and Africa. The new find, in a limestone fossil bed in northeastern Brazil, corrects the mistaken classification of another fossil of this type and reveals that the genus has undergone very little evolutionary change since the Early Cretaceous Period, a time of dinosaurs just before the breakup of the supercontinent Gondwana.

The findings are described in a paper in the open access journal ZooKeys.

“Schizodactylidae, or splay-footed crickets, are an unusual group of large, fearsome-looking predatory insects related to the true crickets, katydids and grasshoppers, in the order Orthoptera,” said University of Illinois entomologist and lead author Sam Heads, of the Illinois Natural History Survey. “They get their common name from the large, paddle-like projections on their feet, which help support their large bodies as they move around their sandy habitats, hunting down prey.”

Although the fossil is distinct from today’s splay-footed crickets, its general features differ very little, Heads said, revealing that the genus has been in a period of “evolutionary stasis” for at least the last 100 million years.

Other studies have found that the region where the fossil was found was most likely an arid or semi-arid monsoonal environment during the Early Cretaceous Period, Heads said, “suggesting that the habitat preferences of Schizodactylus have changed little in over 100 million years.”

Léa Leuzinger, a graduate student at the University of Fribourg, Switzerland, is a co-author on the study.

(Photo: Hwaja Goetz)

University of Illinois

Not Just for Raincoats

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Researchers from Northwestern University and the Massachusetts Institute of Technology (MIT) have studied individual water droplets and discovered a miniature version of the “water hammer,” an effect that produces the familiar radiator pipe clanging in older buildings.

In piping systems, the water hammer occurs when fluid is forced to stop abruptly, causing huge pressure spikes that can rupture pipe walls. Now, for the first time, the researchers have observed this force on the scale of microns: such pressure spikes can move through a water droplet, causing it to be impaled on textured superhydrophobic surfaces, even when deposited gently.

This insight of how droplets get stuck on surfaces could lead to the design of more effective superhydrophobic, or highly water-repellant, surfaces for condensers in desalination and steam power plants, de-icing for aircraft engines and wind turbine blades, low-drag surfaces in pipes and even raincoats. In certain cases, improved surfaces could improve energy efficiency on many orders of magnitude. (About half of all electricity generated in the world comes from steam turbines.)

The research is published by the journal Physical Review Letters.

“We want to design surface textures that will cause the water to really hate those surfaces,” said Neelesh A. Patankar, associate professor of mechanical engineering at Northwestern’s McCormick School of Engineering and Applied Science. “Improving current hydrophobic materials could result in a 60 percent drag reduction in some applications, for example.”

Patankar collaborated with Kripa K. Varanasi, the d’Arbeloff Assistant Professor of Mechanical Engineering at MIT. The two are co-corresponding authors of the paper. Patankar initiated this study in which he and Varanasi led the analytical work, and the experiments were conducted at MIT in Varanasi’s lab. Other co-authors are MIT mechanical engineering graduate students Hyuk-Min Kwon and Adam Paxson.

In designing superhydrophobic surfaces, one goal is to produce surfaces much like the natural lotus leaf. Water droplets on these leaves bead up and roll off easily, taking any dirt with them. Contrary to what one might think, the surface of the leaves is rough, not smooth. The droplets sit on microscopic bumps, as if resting on a bed of nails.

“If a water droplet impales the grooves of this bumpy texture, it becomes stuck instead of rolling off,” Patankar said. “Such transitions are well known for small static droplets. Our study shows that the impalement of water is very sensitive to the dynamic ‘water hammer’ effect, which was not expected.”

To show this, the researchers imaged millimeter-scale water droplets gently deposited onto rough superhydrophobic surfaces. (The surfaces were made of silicon posts, with spacing from post edge to post edge ranging from 40 to 100 microns, depending on the experiment.) Since these drops were on the millimeter scale and being deposited gently, prior understanding was to assume that gravitational force is not strong enough to push the water into the roughness grooves. The Northwestern and MIT researchers are the first to show this is not true.

They observed that as a droplet settles down on the surface (due to the drop’s own weight) there is a rapid deceleration in the drop that produces a brief burst of high pressure, sending a wave through the droplet. The droplet is consequently pinned on the rough surface. That’s the powerful mini water hammer effect at work.

By understanding the underlying physics of this transition, the study reveals that there is actually a window of droplet sizes that avoid impalement. Although focused on drop deposition, this idea is quite general and applies to any scenario where the water velocity is changing on a short (less than a millisecond) time scale. This insight can lead to the design of more robust superhydrophobic surfaces that can resist water impalement even under the dynamic conditions typical in industrial setups.

“One way to reduce impalement is to design a surface texture that results in a surface that sustains extremely high pressures,” Patankar said. “It is the length scale of the roughness that is important.” To resist impalement, the height of a bump and the distance between bumps need to be just right. Hundreds of nanometer scale roughness can lead to robust surfaces.

“Our ultimate goal,” he added, “is the invention of textured surfaces such that a liquid in contact with it will, at least partially, vaporize next to the surface -- or sustain air pockets -- and self-lubricate. This is similar to how an ice skater glides on ice due to a cushion of thin lubricating liquid film between the skates and the ice. A critical step is to learn how to resist impalement of water on the roughness. Our work on water hammer-induced impalement is a crucial advance toward that goal of ultra-slippery vapor stabilizing surfaces.”

(Photo: Northwestern U.)

Northwestern University

Liquids scanner for airport security

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Air passengers one day may be able to carry their soaps, shampoo and bottled water onto the plane again, thanks to technology originally developed at UC Davis to check the quality of wine.

The U.S. Department of Homeland Security’s Science and Technology Directorate recently awarded a contract to a Denver-based defense firm to develop a magnetic resonance scanner that could be placed in airports and used to check bottles and cans for explosives without opening them. A prototype of the machine will be constructed in the laboratory of Matthew Augustine, the UC Davis chemistry professor who invented and patented the technology, with an initial allocation of $800,000.

The technology is similar to the magnetic resonance imaging machines used in medical scanning. It employs a pulse of radio waves and a strong magnetic field to extract a signal that shows the chemical structure of the sample.

Augustine began experimenting with the technology some years ago to check bottles of wine for spoilage without opening them.

That technology was patented in 2002 and licensed by UC Davis to Madison Avenue Management Inc., which set up a subsidiary company, Winescanner Inc., to commercialize it.

After a thwarted 2006 plot in which terrorists planned to carry liquid explosives on board at least 10 transatlantic airliners, Augustine started looking into whether magnetic resonance could be used to identify more than bad wine.

"I'm a tinkerer, I like to build stuff," Augustine said.

Early tests showed that his wine-analysis technique could distinguish gasoline or other dangerous liquids from toothpaste or other innocuous ones.

But the challenge was to design a system suitable for use in airports: relatively small, easy and quick to use, and capable of scanning containers in a wide range of sizes and shapes, from lipsticks to water bottles.

Arriving at such a design involved careful trade-offs between high-frequency radio waves, which give the best information about chemical structures but are blocked by metal, and lower-frequency waves that could pass through a soda can.

University of California, Davis


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Despite decades of research and billions of dollars, cancer remains a major killer, with an uncanny ability to evade both the body’s defenses and medical intervention. Now an Arizona State University scientist believes he has an explanation.

“Cancer is not a random bunch of selfish rogue cells behaving badly, but a highly-efficient pre-programmed response to stress, honed by a long period of evolution,” claims professor Paul Davies, director of the BEYOND Center for Fundamental Concepts in Science at ASU and principal investigator of a major research program funded by the National Cancer Institute designed to bring insights from physical science to the problem of cancer.

In a paper published online Feb. 7 in the UK Institute of Physics journal Physical Biology, Davies and Charles Lineweaver from the Australian National University draw on their backgrounds in astrobiology to explain why cancer cells deploy so many clever tricks in such a coherent and organized way.

They say it’s because cancer revisits tried-and-tested genetic pathways going back a billion years, to the time when loose collections of cells began cooperating in the lead-up to fully developed multicellular life. Dubbed by the authors “Metazoa 1.0,” these early assemblages fell short of the full cell and organ differentiation associated with modern multicellular organisms – like humans.

But according to Davies and Lineweaver, the genes for the early, looser assemblages – Metazoa 1.0 – are still there, forming an efficient toolkit. Normally it is kept locked, suppressed by the machinery of later genes used for more sophisticated body plans. If something springs the lock, the ancient genes systematically roll out the many traits that make cancer such a resilient form of life – and such a formidable adversary.

“Tumors are a re-emergence of our inner Metazoan 1.0, a throwback to an ancient world when multicellular life was simpler,” says Davies. “In that sense, cancer is an accident waiting to happen.”

If Davies and Lineweaver are correct, then the genomes of the simplest multicellular organisms will hide clues to the way that cancer evades control by the body and develops resistance to chemotherapy. And their approach suggests that a limited number of genetic pathways are favored by cells as they become progressively genetically unstable and malignant, implying that cancer could be manageable by a finite suite of drugs in the coming era of personalized medicine.

“Our new model should give oncologists new hope because cancer is a limited and ultimately predictable atavistic adversary,” says Lineweaver. “Cancer is not going anywhere evolutionarily; it just starts up in a new patient the way it started up in the previous one.”

The authors also believe that the study of cancer can inform astrobiology. “It’s not a one-way street,” says Davies. “Cancer can give us important clues about the nature and history of life itself.”

(Photo: Vivek Nandakumar, Center for Biosignatures Discovery Automation, Biodesign Institute, Arizona State University)

Arizona State University


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Recent extreme weather events as far as Australia and Africa are being fueled by a climate phenomenon known as La Niña—or “the girl” in Spanish. La Niña has also played a minor role in the recent cold weather in the Northeast U.S.

The term La Niña refers to a period of cooler-than-average sea-surface temperatures in the Equatorial Pacific Ocean that occurs as part of natural climate variability. This situation is roughly the opposite of what happens during El Niño (“the boy”) events, when surface waters in this region are warmer than normal. Because the Pacific is the largest ocean on the planet, any significant changes in average conditions there can have consequences for temperature, rainfall and vegetation in distant places.

Scientists at the International Research Institute for Climate and Society (IRI), part of Columbia’s Earth Institute, expect moderate-to-strong La Niña conditions to continue in the tropical Pacific, potentially causing additional shifts in rainfall patterns across many parts of the world in months to come.

These shifts, combined with socioeconomic conditions and other factors, are making some countries more vulnerable. However, La Niña and El Niño conditions actually allow for more accurate seasonal forecasts and help better predict extreme drought or rainfall in some areas. That’s because they affect global atmospheric circulation patterns in known ways, and scientists can use this knowledge to help societies prepare better, issue early warnings and reduce any negative impacts associated with them.

"Based on current observations and on predictions from models, we see at least a 90 percent chance that La Niña conditions will continue through March," said IRI's chief forecaster, Tony Barnston.

Climate scientists have found La Niña's fingerprints on a number of extreme weather events such as the devastating flood that occurred in Pakistan in 2010, as well as flooding in West Africa, South Africa and most recently in Queensland, Australia, where an area equal to the combined size of France and Germany was underwater. La Niña is also to blame for Cyclone Yasi, one of the strongest to hit Australia, which came ashore on Feb. 2. Cyclone Yasi is the second most damaging Australian cyclone on record after Cyclone Tracy, which struck in 1974.

But La Niña isn't to blame for the recent severe weather affecting the Northeast. Winter weather for these regions is often driven not by La Niña but by large-scale weather patterns over the U.S., the northern Atlantic Ocean and the Arctic. These are often short-term, and are generally predictable only a week or so in advance. They are the culprits responsible for the dip in temperatures and spike in snow storms in the Midwest and Northeast.

In addition to extreme rainfall, La Niña can lead to drought conditions. Currently in East Africa, it has caused drier-than-usual weather, sparking food-security concerns in areas lacking irrigation, including parts of Somalia, Kenya, Ethiopia and Tanzania. Parts of South America, Asia and the southern U.S. may also see lower rainfall for the first quarter of 2011.

Since 1950, the world has experienced six major La Niña events, wreaking havoc in countries around the world. In 2000, for example, floods associated with La Niña affected 400,000 people in southern Africa, caused at least 96 deaths and left 32,000 homeless.

La Niña conditions typically persist for 9 to 12 months, peaking sometime during the end of the year. But 2010 was a lively year for climate scientists: For the first four months of this year, El Niño conditions prevailed in the tropical Pacific, but that quickly changed, and by June, a La Niña pattern had emerged.

"Last year's transition from El Niño to La Niña was about the most sudden we've ever had," Barnston said. "When we had rapid flips like this in the past, we sometimes ended up having a two-year La Niña, such as right after the El Niño episodes of 1972 to 1973 and 1997 to 1998."

Barnston cautions that the likelihood of this happening with the current La Niña is unknown. "Even if we do have a second year of La Niña developing in northern summer 2011, we expect at least a brief return to neutral conditions from May to July of 2011."

(Photo: NASA)

University of Columbia


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It's an incendiary topic in academia -- the pervasive belief that women are underrepresented in science, math and engineering fields because they face sex discrimination in the interviewing, hiring, and grant and manuscript review processes. In a study published Feb. 7 in the journal Proceedings of the National Academy of Sciences, Cornell social scientists say it's just not true.

It's not discrimination in these areas, but rather, differences in resources attributable to career and family-related choices that set women back in STEM (science, technology, engineering and math) fields, say Stephen J. Ceci, the H.L. Carr Professor of Developmental Psychology, and Wendy M. Williams, professor of human development and director of the Cornell Institute for Women in Science, both in Cornell's College of Human Ecology.

The "substantial resources" universities expend to sponsor gender-sensitivity training and interviewing workshops would be better spent on addressing the real causes of women's underrepresentation, Ceci and Williams say, through creative problem-solving and policy changes that respond to differing "biological and social realities" of the sexes.

The researchers analyzed the scientific literature in which women and men competed for publications, grants or jobs in these fields. They found no systematic evidence of sex discrimination in interviewing, hiring, reviewing or funding when men and women with similar resources -- such as teaching loads and research support -- were compared.

"We hear often that men have a better chance of getting their work accepted or funded, or of getting jobs, because they're men," Williams said. "Universities expend money and time trying to combat this rampant alleged discrimination against women in the hope that by doing so universities will see the numbers of women STEM scientists increase dramatically over coming years."

The data show that women scientists are confronted with choices, beginning at or before adolescence, that influence their career trajectories and success. Women who prioritize families and have children sometimes make "lifestyle choices" that lead them to take positions, such as adjunct or part-time appointments or jobs at two-year colleges, offering fewer resources and chances to move up in the ranks. These women, however, are not held back by sex discrimination in hiring or in how their scholarly work is evaluated. Men with comparably low levels of research resources fare equivalently to their female peers. Although women disproportionately hold such low-resource positions, this is not because they had their grants and manuscripts rejected or were denied positions at research-intensive universities due to their gender.

Also, females beginning before adolescence often prefer careers focusing on people, rather than things, aspiring to be physicians, biologists and veterinarians rather than physicists, engineers and computer scientists. Efforts to interest young girls in these math-heavy fields are intended to ensure girls do not opt out of inorganic fields because of misinformation or stereotypes.

Also, fertility decisions are key because the tenure system has strong disincentives for women to have children -- a factor in why more women in academia are childless than men. Implementation of "flexible options" to enhance work-family balance may help to increase the numbers of women in STEM fields, the researchers say.

As long as women make the choice and "are satisfied with the outcomes, then we have no problem," they write in the paper. "However, to the extent that these choices are constrained by biology and/or society, and women are dissatisfied with the outcomes, or women's talent is not actualized, then we most emphatically have a problem." The solution will only be possible if society focuses on changing the women's non-optimal choices and addressing unique challenges faced by female STEM scientists with children, the researchers say.

(Photo: Cornell U.)

Cornell University




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