Monday, November 23, 2009

TELLING AN OLD BOOK BY ITS SMELL: AROMA HINTS AT WAYS OF PRESERVING TREASURED DOCUMENTS

0 comentarios

Scientists may not be able to tell a good book by its cover, but they now can tell the condition of an old book by its odor. In a report published in the American Chemical Society's Analytical Chemistry, a semi-monthly journal, they describe development of a new test that can measure the degradation of old books and precious historical documents on the basis of their aroma. The non-destructive "sniff" test could help libraries and museums preserve a range of prized paper-based objects, some of which are degrading rapidly due to advancing age, the scientists say.

Matija Strlič and colleagues note in the new study that the well-known musty smell of an old book, as readers leaf through the pages, is the result of hundreds of so-called volatile organic compounds (VOCs) released into the air from the paper.

"The aroma of an old book is familiar to every user of a traditional library," the report notes. "A combination of grassy notes with a tang of acids and a hint of vanilla over an underlying mustiness, this unmistakable smell is as much a part of the book as its contents. It is the result of the several hundred VOCs off-gassing from paper and the object in general. The particular blend of compounds is a result of a network of degradation pathways and is dependent on the original composition of the object including paper substrate, applied media, and binding."

Those substances hold clues to the paper's condition, they say. Conventional methods for analyzing library and archival materials involve removing samples of the document and then testing them with traditional laboratory equipment. But this approach involves damage to the document.

The new technique — an approach called "material degradomics" — analyzes the gases emitted by old books and documents without altering the documents themselves. The scientists used it to "sniff" 72 historical papers from the 19th and 20th centuries. Some of the papers contained rosin (pine tar) and wood fiber, which are the most rapidly degrading types of paper found in old books. The scientists identified 15 VOCs that seem good candidates as markers to track the degradation of paper in order to optimize their preservation. The method also could help preserve other historic artifacts, they add.

(Photo: Wikimedia Commons)

ACS Publications

WARM-BLOODED DINOSAURS WORKED UP A SWEAT

0 comentarios
In a study published in the journal PLoS ONE, a team of researchers, including Herman Pontzer, Ph.D., assistant professor of anthropology in Arts & Sciences, has found strong evidence that many dinosaur species were probably warm-blooded.

If dinosaurs were endothermic (warm-blooded) they would have had the potential for athletic abilities rivalling those of present day birds and mammals, and possibly similar quick thinking and complicated behaviours as well¬. Their internal furnace would have enabled them to live in colder habitats that would kill ectotherms (cold-blooded animals), such as high mountain ranges and the polar regions, allowing them to cover the entire Mesozoic landscape. These advantages would have come at a cost, however; endothermic animals require much more food than their ectothermic counterparts because their rapid metabolisms fatally malfunction if they cool down too much, and so a constant supply of fuel is required.

Pontzer worked with colleagues John R. Hutchinson and Vivian Allen from the Structure and Motion Laboratory at the Royal Veterinary College, UK, to bring a combination of simple measurements, rigorous computer modeling techniques and their knowledge of physiology in present-day animals to bear in a new study on this hot topic. Using their combined experience, the authors set out to determine whether a variety of dinosaurs and closely related extinct animals were endothermic or ectothermic, and when, where and how often in the dinosaur family tree this important trait may have evolved.

"It's exciting to apply our studies of living animals back to the fossil record to test different evolutionary scenarios," Pontzer said. "I work on the evolution of human locomotion, using studies of living humans and other animals to figure out the gait and efficiency of our earliest fossil ancestors. When I realized this approach could be applied to the dinosaur record, I contacted John Hutchinson, an expert on dinosaur locomotion, and suggested we collaborate on this project. Our results provide strong evidence that many dinosaur species were probably warm-blooded. The debate on this issue will no doubt continue, but we hope our study will add a useful new line of evidence."

Studies of present-day animals have shown that endothermic animals are able to sustain much higher rates of energy use (that is, they have a higher "VO2max") than ectothermic animals can. Following this observation, the researches reasoned that if the energy cost of walking and running could be estimated in dinosaurs, the results might show whether these extinct species were warm- or cold-blooded. If walking and running burned more energy than a cold-blooded physiology can supply, these dinosaurs were probably warm-blooded.

But metabolism and energy use are complex biological processes, and all that remains of extinct dinosaurs are their bones. So, the authors made use of a recent work by Pontzer showing that the energy cost of walking and running is strongly associated with leg length – so much so that hip height (the distance from the hip joint to the ground) can predict the observed cost of locomotion with 98% accuracy for a wide variety of land animals. As hip height can be simply estimated from the length of fossilized leg bones, Pontzer and colleagues were able to use this to obtain simple but reliable estimates of locomotor cost for dinosaurs.

To back up these estimates, the authors used a more complex method based on estimating the actual volume of leg muscle dinosaurs would have had to activate in order to move, using methods Hutchinson and Pontzer had previously developed. Activating more muscle leads to greater energy demands, which may in turn require an endothermic metabolism to fuel. Estimating active muscle volume in an extinct animal is a great deal more complicated than measuring the length of the legs, however, and so the authors went back to basic principles of locomotion.

First, how large would the forces required from the legs have to be to move the animal? In present-day animals, this is mainly determined by how much the animal weighs and what sort of leg posture it uses – straight-legged like a human or bent-legged like a bird, for example. Second, how much muscle would be needed to supply these forces? Experiments in biological mechanics have shown that this depends mainly on the limb muscles' mechanical advantage, which in turn depends strongly on the size of the bony levers they are attached to.

To apply these principles to extinct dinosaurs, Pontzer and colleagues examined recent anatomical models of 13 extinct dinosaur species, using detailed measurements of the fossilized bony levers that limb muscles attached to. From this, the authors were able to reconstruct the mechanical advantage of the limb muscles and calculate the active muscle volume required for each dinosaur to walk or run at different speeds. The cost of activating this muscle was then compared to similar costs in present-day endothermic and ectothermic animals.

The results of both the simple and complex method were in very close agreement: based on the energy they consumed when moving, many dinosaurs were probably endothermic, athletic animals because their energy requirements during walking and running were too high for cold-blooded animals to produce. Interestingly, when the results for each dinosaur were arranged into an evolutionary family tree, the authors found that endothermy might be the ancestral condition for all dinosaurs. This pushes the evolution of endothermy further back into the ancient past than many researchers expected, suggesting that dinosaurs were athletic, endothermic animals throughout the Mesozoic era. This early adoption of high metabolic rates may be one of the key factors in the massive evolutionary success that dinosaurs enjoyed during the Triassic, Jurassic and Cretaceous periods, and continue to enjoy now in feathery, flying form.

Their methods add to the many lines of evidence, from bone histology to lung ventilation and insulatory "protofeathers," that are all beginning to support the fundamental conclusion that dinosaurs were generally endothermic. Ironically, indirect anatomical evidence for active locomotion in dinosaurs was originally some of the first evidence used by researchers John Ostrom and Robert Bakker in the 1960s to infer that dinosaurs were endothermic.

Pontzer and his colleagues provide a new perspective on dinosaur anatomy, linking limb design to energetics and metabolic strategies. The debate over dinosaur physiology will no doubt continue to evolve, and while the physiology of long-extinct species will always remain a bit speculative, the authors hope the methods developed in this study provide a new tool for researchers in the field.

PLoS ONE

NEW FOSSIL PLANT DISCOVERY LINKS PATAGONIA TO NEW GUINEA IN A WARMER PAST

0 comentarios

Fossil plants are windows to the past, providing us with clues as to what our planet looked like millions of years ago. Not only do fossils tell us which species were present before human-recorded history, but they can provide information about the climate and how and when lineages may have dispersed around the world. Identifying fossil plants can be tricky, however, when plant organs fail to be preserved or when only a few sparse parts can be found.

In the November issue of the American Journal of Botany (http://www.amjbot.org/cgi/content/full/96/11/2031), Peter Wilf (of Pennsylvania State University) and his U.S. and Argentine colleagues published their recent discovery of abundant fossilized specimens of a conifer previously known as "Libocedrus" prechilensis found in Argentinean Patagonia. This plant was first described in 1938 based on one fossil vegetative branch whose characteristics were said to most closely match those of a living South American dry, cold-climate conifer found in the study area: Austrocedrus (Libocedrus) chilensis, the Cordilleran Cypress.

However, numerous characteristics of the leaves, including their distinctive shape and stomatal arrangements, as well as seed cone details of the newly discovered specimens entirely match those of extant Papuacedrus, a closely related genus, currently found only in tropical, montane New Guinea and the Moluccas.

Based on the newly discovered fossil specimens from 52 and 47 million years ago, Wilf and colleagues reassigned the fossil species to Papuacedrus, under the new name combination Papuacedrus prechilensis. One of the major implications of this reassignment is that, because Papuacedrus is known from tropical montane habitats and is physiologically limited to extremely wet climates, it adds to the emerging evidence that Patagonia in the Eocene was a warm, wet tropical place and not a cold, dry steppe as much of it is today. It also adds a tropical West Pacific connection for Papuacedrus, further establishing the interchange of flora with Australia and neighboring areas via a warm and forested Antarctic land connection during the Eocene. Indeed, less complete Papuacedrus fossils have previously been found in Australia and Antarctica.

"This is a wonderful example of how securely identifying well-preserved and well-dated fossils can have many impacts," Wilf noted. "These fossils contribute critical information about conifer evolution as well as the biogeographic history of the Southern Hemisphere. Combined with the robust site geology we have generated, they also contribute to an important environmental reinterpretation of a large area in the past. Papuacedrus physiologically requires lots of moisture and cannot withstand prolonged droughts."

Another important consequence of this find is how it relates to the great diversity of other fossil plant as well as insect species known from the Patagonian fossil sites. The lush, possibly montane, rainforest environment indicated by Papuacedrus helps to explain this stunning richness from the Eocene. "The revision [of this species] not only forces a major shift in biogeographic affinity (Patagonia to New Guinea), but also provides a decisive boost to important hypotheses of rainforest climates during the Eocene in Patagonia that had not been fully substantiated in previous work," Wilf said. "This in turn helps to explain the remarkable plant and insect diversity found in Eocene Patagonia."

(Photo: P. Wilf)

American Journal of Botany

Followers

Archive

 

Selected Science News. Copyright 2008 All Rights Reserved Revolution Two Church theme by Brian Gardner Converted into Blogger Template by Bloganol dot com