Sunday, October 11, 2009


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An empty store shelf tempts shoppers to buy the next best thing, according to a new study from the University of Alberta.

"Sold-out products create a sense of immediacy for customers; they feel that if one product is gone, the next item could also sell out," said Paul Messinger, a professor at the U of A's School of Business who studied the sale of numerous items including ski passes and wine.

"Our research shows there's also an information cascade, where people infer that if a product is sold out, it must have been good and therefore a similar available product will also be desirable," he said.

The study, published this month in the Journal of Retailing, found 61 per cent of shoppers would buy a particular five-hour ski pass for $20, but that figure rose to 91 per cent when they thought a 10-hour ski pass for the same mountain slope for $40 had sold out.

A similar study of merlot wines found 49 per cent of consumers would buy a bottle if they had one choice, but when they thought a similar wine had sold out next to it on the shelf, nearly twice the number of shoppers would take home the available bottle.

"The use of sold-out signs creates a sense of urgency," said Messinger. The annual phenomenon of a hot toy selling out at Christmas can also be attributed to the information cascade theory, he said.

"You're dealing with toys that parents don't know if their children will like, but millions of consumers are buying it, so they infer that because the item is being purchased, it must be good."

While empty shelves can be frustrating for consumers, Messinger and his co-authors note that the occasional sold-out product can also be a good thing for stores and manufacturers in order to help encourage a sale.

"A lack of stock for common items can indicate to consumers that a store is not managed properly because supply wasn't ordered properly. But for newer items, stores can use it as a message: it wasn't that they didn't order enough, it may be that the product was just selling so fast that nobody could anticipate it, so buy it while you can."

University of Alberta


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Converting the trash that fills the world's landfills into biofuel may be the answer to both the growing energy crisis and to tackling carbon emissions, claim scientists in Singapore and Switzerland. New research published in Global Change Biology: Bioenergy, reveals how replacing gasoline with biofuel from processed waste could cut global carbon emissions by 80%.

Biofuels produced from crops have proven controversial because they require an increase in crop production which has its own severe environmental costs. However, second-generation biofuels, such as cellulosic ethanol derived from processed urban waste, may offer dramatic emissions savings without the environmental catch.

"Our results suggest that fuel from processed waste biomass, such as paper and cardboard, is a promising clean energy solution," said study author Associate Professor Hugh Tan of the National University of Singapore. "If developed fully this biofuel could simultaneously meet part of the world's energy needs, while also combating carbon emissions and fossil fuel dependency."

The team used the United Nation's Human Development Index to estimate the generation of waste in 173 countries. This data was then coupled to the Earthtrends database to estimate the amount of gasoline consumed in those same countries.

The team found that 82.93 billion litres of cellulosic ethanol could be produced from the world's landfill waste and that by substituting gasoline with the resulting biofuel, global carbon emissions could be cut by figures ranging from 29.2% to 86.1% for every unit of energy produced.

"If this technology continues to improve and mature these numbers are certain to increase," concluded co-author Dr. Lian Pin Koh from ETH Zürich. "This could make cellulosic ethanol an important component of our renewable energy future."



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Paleontologists Ewan Wolff (University of Wisconsin-Madison), Steve Salisbury (University of Queensland), Jack Horner (Museum of the Rockies) and David Varricchio (Montana State University), published new research in the open-access, peer-reviewed scientific journal PLoS ONE that found the Tyrannosaurus rex and its close relatives suffered from a potentially life-threatening infectious disease similar to one that occurs in living birds known as trichomonosis.

Trichomonas gallinae infections are most prevalent in pigeons which are generally immune. Birds of prey are particularly susceptible to trichomonosis if they eat infected pigeons. Adult birds can then pass the disease to their nestlings through beak-to-beak contact.

Tell-tale symptoms of trichomonosis include swellings and holes in the back of the lower jaw. The disease is prevented from infecting the entire interior of the bone by the innate immune response that localizes infections as a result of the actions of a unique avian white blood cell called the heterophil.

Some of the world's most famous T. rex specimens, such as 'Sue' at the Field Museum in Chicago, and the holotype specimen at the Carnegie Museum of Natural History in Pittsburgh have holes like these in their lower jaw.

"The holes in tyrannosaur jaws occur in exactly the same place as in modern birds with trichomonosis. The shape of the holes and the way that they merge into the surrounding bone is very similar in both animals," Dr Wolff said.

"The cause of these holes in tyrannosaurs has previously been attributed to tooth gouges from biting or bacterial infections, but we think a trichomonosis-type disease is much more likely given the position and nature of the holes."

The disease appeared to be quite common in tyrannosaurs and could have been deadly to those that were infected.

"As the parasites take hold in serious infections, lesions form around the jaw and inside the throat, eventually eating away the bone. As the lesions grow, the animal has trouble swallowing food and may eventually starve to death," said Dr. Salisbury.

Tyrannosaurs are thus far the only dinosaurs that appear to have had this disease. The researchers therefore faced the problem of explaining how it was spread.

In addition to other routes through which infection may have spread, tyrannosaurs might have facilitated infection by biting each other or even through cannibalism.

"Cannibalism has been tentatively suggested in other studies of theropod behaviour and this certainly could have been a route of transmission for the infection," said Wolff, but he thinks other scenarios were more frequent.

"Fighting and specifically head-biting would have been an ideal mechanism for spreading the disease among tyrannosaurs," said Dr Salisbury.

"We don't think it is a coincidence that a significant number of adult tyrannosaur specimens show both face-biting marks and evidence of a trichomonosis-like disease," Dr Salisbury said. "Previous studies have shown that up to 60% of tyrannosaur specimens display evidence of face-biting."

"In our study we found evidence of face-biting in 30% of the diseased individuals," said Dr Wolff. "Bone pathology is hard to find in any specimen, and bone diseases are relatively uncommon. Finding both types of pathologies in a high proportion of individuals strongly suggests that they could be linked."

"We can see similarities with what has been happening to Tasmanian devils recently, where a debilitating oral cancer is being spread by animals fighting and biting each other's faces," Dr Salisbury said. "This disease may eventually wipe out this iconic Australian mammal."

"It's ironic to think that an animal as mighty as 'Sue' probably died as a result of a parasitic infection. I'll never look at a feral pigeon the same way again." said Salisbury.

The link in disease is not surprising given the evolutionary relationship of dinosaurs to birds. But the discovery of a likely candidate for such a disease represents a major step forward in our understanding of disease origins in birds and their dinosaurian precursors.

"The discovery gives us an insight into the dinosaur immune system. The response of tyrannosaurs to this trichomonosis-like disease is almost identical to that found in living birds," Dr Wolff said. "These simple holes in tyrannosaur jaws give us a dramatic example of an avian-like defence system in action."





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