Friday, April 2, 2010

CAN THE MORPHOLOGY OF FOSSIL LEAVES TELL US HOW EARLY FLOWERING PLANTS GREW?

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Fossils and their surrounding matrix can provide insights into what our world looked like millions of years ago. Fossils of angiosperms, or flowering plants (which are the most common plants today), first appear in the fossil record about 140 million years ago. Based on the material in which these fossils are deposited, it is thought that early angiosperms must have been weedy, fast-growing shrubs and herbs found in highly disturbed riparian stream channels and crevasses.

Dana Royer from Wesleyan University, Connecticut, and colleagues wanted to see if aspects of a fossil plant's life history, such as its growth strategy, could be determined from its morphology rather than from the matrix in which it was deposited. Could this technique corroborate the idea that these ancient plants were fast-growing species? And, importantly, how common was this life history strategy for plants 100 Ma? The results of their research are published in the March issue of the American Journal of Botany (http://www.amjbot.org/cgi/content/full/97/3/438).

The authors first needed to assess whether aspects of leaf morphology in living plants today could accurately predict their life-history strategies. In previous research, Royer and colleagues had found that two simple measurements—petiole width and leaf area—could tell a lot about the ecophysiology of a plant. They found that the ratio of petiole width (squared) to leaf area is correlated to a leaf's dry mass per area.

"Leaf mass per area is a measure of the density or thickness of leaves, and it is strongly linked to how quickly a plant turns over its nutrient resources," Royer said. "Thin, cheaply built leaves (low leaf mass per area) are typically associated with plants with fast growth rates, and plants like these are usually most competitive in highly disturbed environments such as riparian corridors because their rapid growth allows them to be more opportunistic."

The authors measured the petioles and leaf areas of 93 species of living conifers and 58 species of herbaceous angiosperms and compared the resulting leaf mass per areas to those of previously published woody angiosperms. They found that these three groups could be distinguished based on their leaf mass per areas: for a given petiole width, herbaceous herbs tended to have 43%-75% lower leaf mass per area than woody angiosperms, and conifers had 19%-58% higher leaf mass per area than woody angiosperms.

The beauty of this methodology is that leaf petiole width and leaf area are measurable in many fossil specimens. Royer stated that they then used this methodology to "estimate the leaf mass per area for some of the oldest known angiosperm leaf fossils." They measured 179 fossil specimens representing 30 species from three Albian (110-105 Ma) sites across the United States.

"The majority of the fossils measured in our study have low leaf mass per area," noted Royer, supporting the idea that early angiosperms were fast-growing species similar to the flora found in riparian habitats today. If a similar relationship as today is assumed, then all of the fossil angiosperm species had leaf lifespans of less than 12 months. "This means the unrivalled capacity for fast growth observed today in many angiosperms was in place by no later than the Albian (110 Ma ago)."

"While this doesn't tell us anything directly about the earliest angiosperms—the oldest angiosperm pollen is around 140 Ma old—the Albian marks the time when angiosperms begin to be very diverse and important ecologically," Royer concludes. "It is likely that explosive growth is one reason for the success of angiosperms."

(Photo: Courtesy of Dana Royer, Wesleyan University, Middletown, Conn.)

American Journal of Botany

RARE BODY PARTS FIND PROVIDES VITAL CLUES TO IDENTITY OF ANCIENT FOSSIL

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A geologist from the University of Leicester is part of a team that has uncovered an ancient water flea-like creature from 425 million years ago – only the third of its kind ever to be discovered in ancient rocks.

Professor David Siveter, of the Department of Geology at the University of Leicester worked with Professor Derek Siveter at the Oxford University Museum of Natural History, Professor Derek Briggs at Yale University USA and Dr Mark Sutton at Imperial College to make the rare discovery.

The specimen, which was found in rocks in Herefordshire, represents a new species of ostracod, and has been named Nasunaris flata. Like water-fleas and shrimps, ostracods belong to the group of animals called Crustacea. The find is important because the fossil has been found with its soft parts preserved inside the shell.

Today its descendents are common, and inhabit ponds, rivers and lakes and many parts of the seas and oceans, having first appeared on Earth about 500 million years ago.

Geologists find ostracods useful in order to help recreate past environments- the type of ostracod found in a rock sample would, for example, help to determine a picture of ancient conditions like water depth and salinity.

The study is published in the Proceedings of the Royal Society B. and in Planet Earth, the online journal of the Natural Environment Research Council.

Professor David Siveter: "Most fossil ostracod species are known only from their shells. You need exceptional conditions to preserve the soft body- there are only two other known examples of ancient fossil ostracods where the complete soft parts of the animal are preserved along with the shell."

Professor Siveter and colleagues were able to identify the 5mm-long fossil, its body and appendages inside the shell, including the antennae and also a set of paired eyes.

The ostracod was so well preserved that the team managed to spot the Bellonci organ, a sensory structure observed in modern species which protrudes out of the middle eye located at the front of the head. 'This is the first time the Bellonci organ is observed in fossil ostracods,' says David Siveter.

Had the soft body parts not been preserved, the scientists were likely to misidentify the fossil based on the shell record alone, claims Professor Siveter.

(Photo: David J. Siveter, Derek E. G. Briggs, Derek J. Siveter and Mark D. Sutton)

University of Leicester

NEW 'SMART' ROOF READS THE THERMOMETER, SAVES ENERGY IN HOT AND COLD CLIMATES

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Top a building with a light-colored "cool roof," and it reflects sunlight, cutting air conditioning bills in summer, but increasing winter heating costs. Choose black shingles, and the roof soaks up sunlight to cut winter heating costs but makes the roof bake in the summer sun. One or the other. You can't have it both ways. Until now.

Scientists just reported the development of a "smart" roof coating, made from waste cooking oil from fast food restaurants, that can "read" a thermometer. The coating automatically switches roles, reflecting or transmitting solar heat, when the outdoor temperature crosses a preset point that can be tuned to the local climate.

They described the coating at the 239th National Meeting of the American Chemical Society (ACS).

Roofs coated with the material would reflect scorching summer sunlight and reduce sticker-shock air-conditioning bills. When chilly weather sets in, the coating would change roles and transmit heat to help warm the interior.

"This is one of the most innovative and practical roofing coating materials developed to date," said Ben Wen, Ph.D., leader of the research project. He is the vice-president of United Environment & Energy LLC in Horseheads, N.Y. "This bio-based intelligent roof coating, compared with a traditional cool roof, could reduce both heating and cooling costs as it responds to the external environment. It will help save fuel and electricity and reduce emissions of volatile organic compounds from petroleum-based roofing products. In addition, it will provide a new use for millions of gallons of waste oil after it is used to cook french fries and chicken nuggets."

Scientists already have evidence that "white roofs" — roofs that are painted white to reflect solar heat and help cool buildings during peak summer weather — could significantly reduce global warming by lowering fuel consumption. However, white roofs can have a wintertime heating penalty because they reflect solar heat that would help warm the building. So white roofs are a benefit in summer but a detriment in winter.

The new "intelligent" coating may sidestep this quandry. Tests on coated asphalt shingles showed that it could reduce roof temperatures by about 50 – 80 percent in warm weather. In cooler weather, the coating could increase roof temperatures up to 80 percent compared with the traditional cool roof. By changing the coating's composition, Wen and colleagues can tune the substance, so that it changes from reflective to transmitive at a specific environmental temperature.

"Even though the roof temperature is reduced or increased by a few degrees, depending on the outside temperature, this change could make a big difference in your energy bill," Wen noted.

In producing the coating, waste cooking oil is processed into a liquid polymer that hardens into a plastic after application. Unlike raw waste oil, which can smell like French fries or fish, the resulting polymer is virtually odorless. Manufacturers could potentially produce it in any shade, ranging from clear to black, depending on what additives are used, he said. The material is also non-flammable and nontoxic.

Wen cautions against pouring ordinary cooking oil on a roof in an attempt to achieve a similar energy-saving effect. That's because ordinary cooking oil won't turn into a polymer, doesn't contain the key ingredient for controlling infrared light levels, and could well pose a fire hazard for the building.

The coating can be applied to virtually any type of roof. Wen expects that the coating can last many years and can be reapplied when it wears off. If further testing continues to go well, he estimates that the coating could be ready for commercial use in about three years.

(Photo: Ben Wen, Ph.D)

American Chemical Society

PEOPLE ARE LIVING LONGER AND HEALTHIER -- NOW WHAT?

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People in developed nations are living in good health as much as a decade longer than their parents did, not because aging has been slowed or reversed, but because they are staying healthy to a more advanced age.

"We're living longer because people are reaching old age in better health," said demographer James Vaupel, author of a review article appearing in the March 25 edition of Nature. But once it starts, the process of aging itself -- including dementia and heart disease -- is still happening at pretty much the same rate. "Deterioration, instead of being stretched out, is being postponed."

The better health in older age stems from public health efforts to improve living conditions and prevent disease, and from improved medical interventions, said Vaupel, who heads Duke University's Center on the Demography of Aging and holds academic appointments at the Max Planck Institute for Demographic Research in Rostock, Germany, and the institute of Public Health at the University of Southern Demark.

Over the past 170 years, in the countries with the highest life expectancies, the average life span has grown at a rate of 2.5 years per decade, or about 6 hours per day.

The chance of death goes up with age up until the most advanced ages. The good news is that after age 110, the chance of death does not increase any more. The bad news is that it holds steady at 50% per year at that point, Vaupel said.

"It is possible, if we continue to make progress in reducing mortality, that most children born since the year 2000 will live to see their 100th birthday -- in the 22nd century," Vaupel said. If gains in life expectancy continue to be made at the same pace as over the past two centuries, more than half of the children alive today in the developed world may see 100 candles on their birthday cake.

This leads to an interesting set of policy questions, said Vaupel. What will these dramatically longer lifespans mean for social services, health care and the economy? Can the aging process be slowed down or delayed still further? And why do women continue to outlive men – outnumbering them 6 to 1 at age 100?

It also may be time to rethink how we structure our lives, Vaupel said. "If young people realize they might live past 100 and be in good shape to 90 or 95, it might make more sense to mix education, work and child-rearing across more years of life instead of devoting the first two decades exclusively to education, the next three or four decades to career and parenting, and the last four solely to leisure."

One way to change life trajectories would be to allow younger people to work fewer hours, in exchange for staying in the workforce to a later age. "The 20th century was a century of the redistribution of wealth; the 21st century will probably be a century of the redistribution of work," Vaupel said.

(Photo: Michael Ströck: Wikimedia Commons)

Duke University

PULLING POWER POINTS THE WAY TO THE WORLD'S STRONGEST INSECT

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Following months of gruelling tests and trials, scientists now reveal the World's strongest insect to be a species of dung beetle called Onthophagus taurus.

In an experiment to find out why animals vary so much in strength and endurance, Dr Rob Knell from Queen Mary, University of London and Professor Leigh Simmons from the University of Western Australia found the strongest beetle could pull an astonishing 1,141 times its own body weight - the equivalent of a 70kg person lifting 80 tonnes (the same as six full double-decker buses).

Writing in the journal Proceedings of the Royal Society B, the scientists also found these insect athletes need to pay just as much attention to their diet as human athletes. Even the strongest beetles were reduced to feeble weaklings when put on a poor diet for a few days.

"Insects are well known for being able to perform amazing feats of strength," explained Dr Knell from Queen Mary's School of Biological and Chemical Sciences, "and it's all on account of their curious sex lives. Female beetles of this species dig tunnels under a dung pat, where males mate with them. If a male enters a tunnel that is already occupied by a rival, they fight by locking horns and try to push each other out." Knell and Simmons tested the beetles' ability to resist a rival by measuring how much weight was needed to pull him out of his hole.

"Interestingly, some male dung beetles don't fight over females," said Dr Knell. "They are smaller, weaker and don't have horns like the larger males. Even when we fed them up they didn't grow stronger, so we know it's not because they have a poorer diet.
"They did, however, develop substantially bigger testicles for their body size. This suggests they sneak behind the back of the other male, waiting until he's looking the other way for a chance to mate with the female. Instead of growing super strength to fight for a female, they grow lots more sperm to increase their chances of fertilising her eggs and fathering the next generation."

(Photo: © Alex Wild)

Queen Mary, University of London

OUR EYE POSITION BETRAYS THE NUMBERS WE HAVE IN MIND

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It will be harder to lie about your age or your poker hand after new research by the University of Melbourne, Australia has revealed that our eye position betrays the numbers we are thinking about.

In the study, participants were asked to state a series of random numbers. By measuring their vertical and horizontal eye position, researchers were able to predict with reliable confidence the next chosen number - before it was spoken.

Specifically, a leftward and downward change in eye position announced that the next number would be smaller than the last. Correspondingly, if the eyes changed position to the right and upward, it forecast that the next number would be larger. The degree of eye movement reflected the size of the numerical shift.

The paper was published today online in the prestigious journal Current Biology.

First author, Dr Tobias Loetscher of the University of Melbourne's School of Behavioural Sciences and previously of the Department of Neurology, University Hospital Zurich, Switzerland says the research demonstrates how the eyes and their position give insight into the nature of the systematic choices made by the brain's random number generator.

"When we think of numbers we automatically code them in space, with smaller number falling to the left and larger numbers to the right. That is, we think of them along a left-to-right oriented mental number line - often without even noticing this number-space association ourselves."

"This study shows that shifts along the mental number line are accompanied by systematic eye movements. We suggest that when we navigate through mental representations - as for example numbers - we re-use brain processes that primarily evolved for interacting and navigating in the outside world."

Dr Michael Nicholls also of the School of Behavioural Sciences adds, "Clearly, the eyes not only allow us to see the world around us, but they also present a window to the working of our mind, as this study shows."

"This study will hopefully provide a template to investigate how the human mind works via a connection with the space and world around us," he says.

The study involved asking twelve right-handed men to select from a set of random numbers. Paced by an electronic metronome they named 40 numbers between 1 and 30 in a sequence as random as possible. For each number, the researchers measured the average eye position during the 500 millisecond interval before the numbers were stated.

University of Melbourne

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