Led by Ekkehart Boehmer of the Mays Business School at Texas A&M University, Charles M. Jones of the Graduate School of Business at Columbia University, and Xiaoyan Zhang, of the Johnson Graduate School of Management at Cornell University, researchers used information from the New York Stock Exchange to examine the incidence and information content of short sales. Used to measure shorting flow, the sample consisted of all NYSE system order data records related to short sales from January 2000 to April 2004.

The study shows that there is a surprisingly large amount of shorting activity across both large and small NYSE stocks. During the sample period, shorting accounted for at least 12.9 % of trading volume, suggesting that shorting constraints are easily surmounted and not widespread.

The study also illustrates the extent to which short sellers are able to identify overvalued stocks and profit by anticipating price declines in these stocks. Short sellers are extremely well-informed, with institutional traders being the most informed.

The results are consistent with the emerging consensus in financial economics that short sellers possess important information, and that their trades are important contributors to more efficient stock prices.

"We think this is a promising area of research, and our high frequency data are ideal for investigating short selling immediately surrounding these kinds of corporate events," the authors conclude.

Discovery Theory is categorized by the idea that entrepreneurial opportunities exist, independent of the perceptions of entrepreneurs, just waiting to be discovered. In contrast, Creation Theory holds that these opportunities are created by the actions of entrepreneurs.

Led by Sharon A. Alvarez and Jay B. Barney of the Fisher College of Business at Ohio State University, researchers explored these theories of entrepreneurship and their implications for the actions of entrepreneurs.

Both Discovery and Creation theory assume the goal of entrepreneurs is to form and exploit opportunities. However, the theories often generate different predictions about when specific actions will be more or less effective in enabling entrepreneurs to form these opportunities.

Only when the theories are linked to specific actions can they have repercussions. The study reviews the implications of discovery and creation assumptions for seven actions, including leadership, decision making, human resource practices, strategy, finance, marketing, and sustaining competitive advantages.

When entrepreneurs operate in a discovery context, a variety of specific actions are likely to be most effective. When they operate in a creation context, a different set of entrepreneurial actions are likely to be most effective.

For example, when exploring the entrepreneurial action of leadership, when operating in a discovery context it would be best for the entrepreneur to lead based on expertise and experience. However, if operating within a creation context, it would be best to lead based on charisma.

"Future research in entrepreneurship will need to carefully examine the context under which entrepreneurs are operating," the authors conclude. "Understanding the implications of these two theories for the effectiveness of a wide variety of entrepreneurial actions is important."

The results of the research, entitled "Episodic-Like Memory in Rats: Is it Based on When or How Long Ago," appear in the current issue of the journal Science, which was released today.

William Roberts and his colleagues in Western's Psychology Department found that rats are able to keep track of how much time has passed since they discovered a piece of cheese, be it a little or a lot, but they don't actually form memories of when the discovery occurred. That is, the rats can't place the memories in time.

The research team, led by Roberts, designed an experiment in which rats visited the 'arms' of a maze at different times of day. Some arms contained moderately desirable food pellets, and one arm contained a highly desirable piece of cheese. Rats were later returned to the maze with the cheese removed on certain trials and with the cheese replaced with a pellet on others.
All told, three groups of rats were tested in the research using three varying cues: when, how long ago or when plus how long ago.

Only the cue of how long ago food was encountered was used successfully by the rats.

These results, the researchers say, suggest that episodic-like memory in rats is qualitatively different from human episodic memory, which involves retention of the point in past time when an event occurred.

""The rats remember whether they did something, such as hoarded food a few hours or five days ago," explained Roberts. "The more time that has passed, the weaker the memory may be. Rats may learn to follow different courses of action using weak and strong memory traces as cues, thus responding differently depending on how long ago an event occurred. However, they do not remember that the event occurred at a specific point in past time."

Previous studies have suggested that rats and scrub jays (a relative of the crow and the blue jay) appear to remember storing or discovering various foods, but it hasn't been clear whether the animals were remembering exactly when these events happened or how much time had elapsed.

"This research," said Roberts, "supports the theory I introduced that animals are stuck in time, with no sense of time extending into the past or future."

The fish, sighted in Indonesian waters off Ambon Island, has tan- and peach-colored zebra-striping, and rippling folds of skin that obscure its fins, making it look like a glass sculpture that Dale Chihuly might have dreamed up. But far from being hard and brittle like glass, the bodies of these fist-sized fish are soft and pliable enough to slip and slide into narrow crevices of coral reefs. It’s probably part of the reason that they've typically gone unnoticed – until now.

The individuals are undoubtedly anglerfishes, says Ted Pietsch, a UW professor of aquatic and fishery sciences who has published 150 scholarly articles and several books on anglerfishes and is the world's leading authority on them. In the last 50 years scientists have described only five new families of fishes and none of them were even remotely related to anglerfishes, Pietsch says.

Husband and wife Buck and Fitrie Randolph, with dive guide Toby Fadirsyair, found and photographed an individual Jan. 28 in Ambon harbor. A second adult has since been seen and two more – small, and obviously juveniles – were spotted March 26, off Ambon. One of the adults laid a mass of eggs, just spotted Tuesday.

The Randolphs are part-owners of Maluku Divers, a land-based dive facility in Ambon City. Toby Fadirsyair, who works for Maluku Divers, said he may have seen something similar 10 or 15 years ago but the coloring was different.

Reference books were consulted but nothing similar to the fish photographed in January was found. Seeking international fish experts eventually led them to Pietsch.

"As soon as I saw the photo I knew it had to be an anglerfish because of the leglike pectoral fins on its sides," Pietsch says. "Only anglerfishes have crooked, leglike structures that they use to walk or crawl along the seafloor or other surfaces."

Anglerfishes – also called by names like frogfishes and toadfishes – are found the world over and typically have lures growing from their foreheads that they wave or cause to wiggle in order to attract prey. Get too close to the lure and you're lunch.

The newly found individuals have no lures so they seek their prey differently, burrowing themselves into crevices and cracks of coral reefs in search of food.

"Several times I saw these fish work themselves through an opening that seemed much smaller than the fish, sometimes taking a minute or more to get all the way through," says David Hall, an underwater natural history photographer who was able to dive with Maluku Divers and take additional photos of the new find. "They must have pretty tough skin to keep from being scraped and cut, but there is no evidence of superficial injury or scars in my photographs."

With its unusual flattened face, the fish's eyes appear to be directed forward, something Pietsch says he's never seen in 40 years as an icthyologist, a scientist who studies the structure, classification and habits of fishes. Most fishes have eyes on either side of their head so that each eye sees something different. Only very few fishes have eyes whose radius of vision overlaps in front, providing binocular vision, a special attribute well developed in humans that provides the ability to accurately judge distance.

Randolph, a longtime diver, says the similar color pattern of the two adults surprises him because he typically sees variations in skin color between members of the same anglerfish species and has even seen individual anglerfish that change colors depending on the surroundings.

Whether the new fish represent a new family will entail DNA testing and a close examination of a specimen, says Pietsch, whose anglerfish work is currently funded by the National Science Foundation. Scientists have already described 18 different families of anglerfishes and this is probably a 19th, Pietsch says. Families are large groupings, for example, all dog species belong to the larger family that includes wolves, coyotes and, even, hyenas. One can see an example of an anglerfish family, the one named Antennariidae, at http://www.tolweb.org/Antennariidae/21993, a part of the Tree of Life Web project.

When only a single fish had been sighted, Randolph and Andy Shorten, co-owner of Maluku Divers, kept the find quiet to protect the animal. With more individuals being found, and having a better idea of where to look to find others, the two became comfortable enough to post images on the firm's Web site, see http://www.divingmaluku.com/new-frogfish.

"Seeking out these fish is probably going to be like the Holy Grail of divers for a while," Shorten says. Indeed just do a Google search for "new frogfish Ambon" on the Internet and up pops a lot of dive sites carrying news of the find.

"I don't think it will turn out that there are a lot of these animals but all that scrutiny will help us find out for sure," Shorten says.

For example, 35 years ago nobody realized pygmy seahorses existed but once they were discovered and people understood where to look for them, they turned out to be widespread throughout the ocean.

The fish were seen in 15 feet of water. It's possible the fish could be found at other locations, Pietsch says. All other anglerfish families have ranges broader than a single island group and ocean conditions like those at Ambon are found at various places across Indo-Australian waters.

In a recent issue of the Annals of Neurology, the official journal of the American Neurological Association, authors Antonio Zadra, Mathieu Pilon and Jacques Montplaisir explain how they evaluated 40 suspected sleepwalkers. Each was referred to the Sleep Research Centre at Sacré-Coeur Hospital, a Université de Montréal teaching hospital, between August 2003 and March 2007.

"Our study found that sleep deprivation can precipitate sleepwalking in predisposed individuals," said lead investigator Antonio Zadra. "Sleepwalkers are best to maintain a regular bedtime and avoid sleep deprivation if they wish to steer clear of somnambulism."

Subjects who took part in the study agreed to have their baseline sleep patterns monitored during an initial all-night assessment. During a subsequent visit, patients were kept awake for the entire evening and remained under constant supervision.

Recovery sleep was allowed the next morning after patients had been awake for 25 hours. Subjects were videotaped during each sleep period as the research team evaluated their behaviour, which ranged from playing with bed sheets to trying to jump over the bed rails. Subjects were evaluated on a three-point scale based on the complexity of their actions.

Results were striking. During baseline sleep, only half of patients exhibited some 32 behavioral episodes. During recovery sleep, 90 percent of patients demonstrated a total of 92 behavioral episodes.

The study also found that sleepwalkers, previously thought to suffer from an inability to sustain slow-wave or deep sleep, had increased difficulty in passing from slow-wave sleep to another sleep stage or to be fully awake following sleep deprivation. "This research also reveals that objective methods can now be used for investigating and diagnosing sleepwalking," said Dr. Zadra.

A simple idea for monitoring earthquakes that Elizabeth Cochran, a seismologist at UC Riverside, came up with in 2006 is being realized today, and has the potential to save lives in case an earthquake strikes.

The idea involves inviting the public to help monitor earthquakes by simply using their laptop computers at home. In doing so, the laptops join a network of computers designed to take a dense set of measurements that can help capture an earthquake.

Anyone with a personal computer will be able to participate in the experiment once software linking such computers to the project is publicly released, tentatively this summer. The free software, being developed by Cochran and colleagues Jesse Lawrence of Stanford University and Carl Christensen, a software architect and consultant, will be available at the Website BOINC.

Because the project makes use of inexpensive motion sensors, called accelerometers, which are already in place as safety devices in most new laptops, participants incur no significant costs related to the project.

Called "Quake-Catcher Network," the project involves distributed computing, a method in which different parts of a computer program run simultaneously on two or more computers that are in communication with a central server over a network.

"We're turning the laptops' accelerometers into earthquake monitors," said Cochran, an assistant professor of seismology in the Department of Earth Sciences. "With a dense grid of detectors in place, an early warning can be sent through the Internet to neighboring cities should an earthquake strike, giving people up to 10-20 seconds to prepare themselves before the seismic waves reach them."

Already, about 300 people spread around the world are taking part in the Quake-Catcher Network, with roughly a third of the participants in the United States.

"The idea is to fill in the spaces - or holes - in the seismic network currently being used to report earthquakes," Cochran said. "With the public's participation in Quake-Catcher Network, however, we can have a lot more 'stations' recording earthquakes, allowing for a better early warning system. At present in California, no such early warning system for earthquakes exists."

Currently, approximately 350 stations monitor earthquakes in Southern California using underground sensors. They do so, however, not in real time.

"There is a delay of 10-15 seconds from when the sensors record an earthquake to when the data is processed at either Caltech in Southern California or UC Berkeley in Northern California," Cochran explained. "Quake-Catcher Network would process data in real time, as it comes in. And the network can stretch out to any region of the world. Besides being inexpensive, it makes an extremely small demand on CPU resources."

According to Cochran, a person's laptop needs to remain inactive for at least three minutes before the system starts up. "This is to get rid of noise in the data and to ensure that any movement the laptop's accelerometer is detecting is indeed out of the ordinary," she said.

Currently, only Apple computers can participate in the project, but Cochran and her colleagues are working on including other computers in Quake-Catcher Network.

"We also are working on developing an accelerometer which can be plugged into a desktop like a USB flash drive," she said. "That way, we'd have less interference from typing on the keyboard. It also would allow for a more robust and reliable system, with computers running the software all of the time."

Cochran said she plans to make all the data gathered by the sensors freely available to researchers and the public.

"This data can be used to study how a seismic wave propagates in the ground," she said. "How fast a wave travels can give us useful information, such as more details on seismic hazard as well as the structure of the Earth. The denser our network, the clearer will be the picture of what is happening at each step in time. A series of such pictures could be used to develop a movie showing the wave's propagation, which could give us extremely useful information about seismic waves."

Next, Cochran and her colleagues will further test their software program before its release on BOINC; currently, the program is available on very limited release.

Cochran also plans to involve K-12 schools through education and outreach. "We think this would be an excellent project for students to take an interest in," she said, "so we're hoping we'll see more of their participation."

The Spitzer Space Telescope, trained on the star AA Tauri, has revealed traces of abundant water and simple organic molecules in the inner disk of dust and gas surrounding the very young star thought to be similiar to our early sun.

Lilliard Richardson, professor in the MU Truman School of Public Affairs, and David J. Houston, associate professor at the University of Tennessee, Knoxville, compared the changes in helmet laws across all 50 states and the District of Columbia from 1975 through 2004. In states where repeals of universal coverage were instituted, the fatality rate increased an average of 12.2 percent. Conversely, in states with universal helmet laws, the fatality rate was 11.1 percent lower than in states with no helmet mandates.

"Previous studies have been limited to certain states and fail to distinguish the states with partial coverage from those with no legislation," Richardson said. "Our focus was not limited to a single state or a single change. We looked at effects in states that went from universal helmet laws to partial laws and states that went from partial laws to no laws, and states which kept their laws in place. We highlighted repeals of laws in six states by using separate variables to distinguish the effects of universal and partial coverage. We included controls for temperature, precipitation, per capita alcohol consumption, income, age, population density and other traffic safety policies."

Experts have estimated that an additional 615 motorcyclist fatalities occurred in the six states that repealed motorcycle helmet laws from 1997 to 2004, Richardson said. The researchers also found that fatality numbers in states with partial laws were not statistically different from those with no helmet laws.

"The federal government has pressured states to adopt universal helmet laws, but the trend has been toward more state control of helmet laws," Richardson said. "The National Highway Traffic Safety Administration promotes the effectiveness of helmet laws for getting motorcyclists to wear helmets, but there is no strategy for encouraging states to maintain or adopt universal coverage laws. This does not bode well for the future of universal helmet laws and motorcycle safety in the United States."

Currently, several states are considering modifying their helmet laws.

"Advocates in many states are pushing to repeal state universal helmet laws or impose partial mandates that require only young riders to wear helmets," Richardson said. "Many assume that wearing helmets becomes a habit for riders like wearing a seatbelt is for drivers and that having a law in place isn't necessary. This is a misconception. When laws aren't in place and enforced, the evidence shows that a majority of riders do not wear helmets."

The study, "Motorcycle Safety and the Repeal of Universal Helmet Laws," was published in the American Journal of Public Health.

The transistors are made of "nanowires," tiny cylindrical structures that are assembled on glass or thin films of flexible plastic. The researchers used nanowires as small as 20 nanometers - a thousand times thinner than a human hair - to create a display containing organic light emitting diodes, or OLEDS. The OLEDS are devices that rival the brightness of conventional pixels in flat-panel television sets, computer monitors and displays in consumer electronics.

"This is a step toward demonstrating the practical potential of nanowire transistors in displays and for other applications," said David Janes, a researcher at Purdue University's Birck Nanotechnology Center and a professor in the School of Electrical and Computer Engineering.

The nanowires were used to create a proof-of-concept active-matrix display similar to those in television sets and computer monitors. An active-matrix display is able to precisely direct the flow of electricity to produce video because each picture element, or pixel, possesses its own control circuitry.

Findings will be detailed in a research paper featured on the cover of the April issue of the journal Nano Letters. The paper was written by researchers at Purdue, Northwestern University and the University of Southern California.

"We've shown how to fabricate nanowire electronics at room temperature in a simple process that might be practical for commercial manufacturing," said Tobin J. Marks, the Vladimir N. Ipatieff Research Professor in Chemistry in Northwestern's Weinberg College of Arts and Sciences and a professor of materials science and engineering.

OLEDS are now used in cell phones and MP3 displays and prototype television sets, but their production requires a complex process, and it is difficult to manufacture OLEDs that are small enough for high-resolution displays.

"Nanowire-transistor electronics could solve this problem," said Marks, who received a 2005 National Medal of Science. "We think our fabrication method is scalable, possibly providing a low-cost way to produce high-resolution displays for many applications."

Unlike conventional computer chips - called CMOS, for complementary metal oxide semiconductor chips - the nanowire thin-film transistors could be produced less expensively under low temperatures, making them ideal to incorporate into flexible plastics that would melt under high-temperature processing.

Conventional liquid crystal displays in flat-panel televisions and monitors are backlit by a white light, and each pixel acts as a filter that turns on and off to create images. OLEDS, however, emit light directly, eliminating the need to backlight the screen and making it possible to create more vivid displays that are thin and flexible.

The technology also could be used to create antennas that aim microwave and radio signals more precisely than current antennas. Such antennas might improve cell phone reception and make it more difficult to eavesdrop on military transmissions on the battlefield.

Electronic displays like television screens contain millions of pixels located at the intersections of rows and columns that crisscross each other. In the new findings, the researchers showed that they were able to selectively illuminate a specific row of active-matrix OLEDS in a display about the size of a fingernail.

"Displays in television sets are able to illuminate a particular pixel located, say, in the 10th row, fifth column," Janes said. "We aren't able to do that yet. We've shown that we can select a whole row at a time, not a single OLED, but we're getting close."

Future research is expected to include work to design displays that can control individual OLEDs to generate images, Janes said.

"A unique aspect of these displays is that they are transparent," he said. "Until the pixels are activated, the display area looks like lightly tinted glass."

The nanowire transistors are made of a transparent semiconductor called indium oxide, a potential replacement for silicon in future transparent circuits. The OLEDS consist of the transistors, electrodes made of a material called indium tin oxide and plastic capacitors that store electricity. All of the materials are transparent until activated to emit light.

"This could enable applications such as GPS navigational displays right on the windshield of your car," Janes said. "Imagine having a local map displayed on your windshield so that you didn't have to take your eyes off the road."

The new OLEDs have a brightness nearly comparable to that of the pixels in commercial flat-panel television sets. The OLEDS have an average brightness of more than 300 candelas per square meter, compared with 400-500 candelas per square meter for commercially available liquid-crystal display televisions.

"Even in this first demonstration, we are fairly close to the brightness you'd see in an LCD television," Janes said.

The researchers also demonstrated they could create OLEDS of the proper size for commercial displays, about 176 by 54 microns, or millionths of a meter. OLEDS that size would be ideal for small displays in cell phones, personal digital assistants and other portable electronics.

Biologists have long puzzled over the relationship between evolution of complex traits and the randomness of mutations in genes. Some have proposed that a "cost of complexity" makes it more difficult to evolve a complicated trait by random mutations, because effects of beneficial mutations are diluted.

"While a mutation in a single gene can have effects on multiple traits, even as diverse as the structures of brain, kneecap and genitalia, we wondered how often random mutation would affect many traits" said lead author Gunter Wagner, professor and chair of ecology and evolutionary biology at Yale. The phenomenon wherein mutation in a single gene can have effects on multiple traits is known as pleiotropy.

This study showed that most mutations only do affect few traits. Further, the effect of an individual mutation is not dampened because of its effects on other traits.

Observing 70 skeletal characteristics in the mouse, the researchers identified total of 102 genomic regions that affect the skeleton. They concluded that substitution in each genome segment affected a relatively small subset of characteristics and that the effect on each characteristic increased with the total number of traits affected.

"You wouldn't expect to make a lot of random adjustments - at the same time - to tune up a car," said Wagner. "Similarly, it appears that tuning up a complex trait in a living organism is well coordinated and the effects of pleiotropy are more focused than we thought."

When sand dollar larvae sense mucus produced by nearby predator fish, they start cloning themselves, scientists have found. The clones are smaller than regular larvae, which may give them an advantage because they are more difficult for the fish to detect.

While larval cloning is well-documented in echinoderms, itʼs generally been thought of as a means to improve growth and reproduction, not as a defense against predators.