Friday, June 25, 2010

NEW INSIGHTS INTO VOLCANIC ACTIVITY ON THE OCEAN FLOOR

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New research reveals that when two parts of the Earth's crust break apart, this does not always cause massive volcanic eruptions. The study, published today in the journal Nature, explains why some parts of the world saw massive volcanic eruptions millions of years ago and others did not.

The Earth's crust is broken into plates that are in constant motion over timescales of millions of years. Plates occasionally collide and fuse, or they can break apart to form new ones. When the latter plates break apart, a plume of hot rock can rise from deep within the Earth's interior, which can cause massive volcanic activity on the surface.

When the present-day continent of North America broke apart from what is now Europe, 54 million years ago, this caused massive volcanic activity along the rift between the two. Prior to today's study, scientists had thought that such activity always occurred along the rifts that form when continents break apart.

However, today's research shows that comparatively little volcanic activity occurred when the present-day sub-continent of India broke away from what is now the Seychelles, 63 million years ago.

Researchers had previously believed that the temperature of the mantle beneath a plate was the key to determining the level of volcanic activity where a rift occurred. The new study reveals that in addition, the prior history of a rift also strongly influences whether or not volcanic activity will occur along it.

In the case of the break-up of America from Europe, massive volcanic activity occurred along the rift because a previous geological event had thinned the plate, according to today's study. This provided a focal point where the mantle underneath the plate could rapidly melt, forming magma that erupted easily through the thinned plate and onto the surface, in massive outbursts of volcanic activity.

In comparison, when India broke away from the Seychelles very little volcanic activity occurred along the North Indian Ocean floor, because the region had experienced volcanic activity in a neighbouring area called the Gop Rift 6 million years earlier. This exhausted the supply of magma and cooled the mantle, so that when a rift occurred, very little magma was left to erupt.

Dr Jenny Collier, co-author from the Department of Earth Science and Engineering at Imperial College London, says: "Mass extinctions, the formation of new continents and global climate change are some of the effects that can happen when plates break apart and cause super volcanic eruptions. Excitingly, our study is helping us to see more clearly some of the factors that cause the events that have helped to shape the Earth over millions of years."

The team reached their conclusions after carrying out deep sea surveys of the North Indian Ocean to determine the type of rock below the ocean floor. They discovered only small amounts of basalt rock, which is an indicator of earlier volcanic activity .The team also used new computer models that they had developed to simulate what had happened along the ocean floor in the lead up to India and the Seychelles splitting apart.

Dr John Armitage, lead author of the paper from the Department of Earth Science and Engineering at Imperial College London, adds: "Our study is helping us to see that the history of the rift is really important for determining the level of volcanic activity when plates break apart. We now know that this rift history is just as important as mantle temperature in controlling the level of volcanic activity on the Earth's surface."

In the future, the team hope to further explore the ocean floor off the coast of South America where that continent split from Africa millions of years ago to determine the level of ancient volcanic activity in the region.

(Photo: ICL)

Imperial College London

EMORY STUDY SHOWS BABIES GRASP NUMBER, SPACE AND TIME CONCEPTS

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Even before they learn to speak, babies are organizing information about numbers, space and time in more complex ways than previously realized, a study led by Emory University psychologist Stella Lourenco finds.

"We've shown that 9-month-olds are sensitive to 'more than' or 'less than' relations across the number, size and duration of objects. And what's really remarkable is they only need experience with one of these quantitative concepts in order to guess what the other quantities should look like," Lourenco says.

Lourenco collaborated with neuroscientist Matthew Longo of University College London for the study, to be published in an upcoming issue of Psychological Science.

In his 1890 masterwork, "The Principles of Psychology," William James described the baby's impression of the world as "one great blooming, buzzing confusion."

Accumulating evidence is turning that long-held theory on its head.

"Our findings indicate that humans use information about quantity to organize their experience of the world from the first few months of life," Lourenco says. "Quantity appears to be a powerful tool for making predictions about how objects should behave."
Lourenco focuses on the development of spatial perception, and how it interfaces with other cognitive dimensions, such as numerical processing and the perception of time. Previous research suggests that these different cognitive domains are deeply connected at a neural level. Tests show, for instance, that adults associate smaller numbers with the left side of space and larger numbers with the right.

"It's like we have a ruler in our heads," Lourenco says of the phenomenon.

Other tests show that when adults are asked to quickly select the higher of two numbers, the task becomes much harder if the higher number is represented as physically smaller than the lower number.

Lourenco wanted to explore whether our brains just pick up on statistical regularities through repeated experience and language associations, or whether a generalized system of magnitude is present early in life.

Her lab designed a study that showed groups of objects on a computer screen to 9-month-old infants. "Babies like to stare when they see something new," Lourenco explains, "and we can measure the length of time that they look at these things to understand how they process information."

When the infants were shown images of larger objects that were black with stripes and smaller objects that were white with dots, they then expected the same color-pattern mapping for more-and-less comparisons of number and duration. For instance, if the more numerous objects were white with dots, the babies would stare at the image longer than if the objects were black with stripes.

"When the babies look longer, that suggests that they are surprised by the violation of congruency," Lourenco says. "They appear to expect these different dimensions to correlate in the world."

The findings suggest that humans may be born with a generalized system of magnitude. "If we are not born with this system, it appears that it develops very quickly," Lourenco says. "Either way, I think it's amazing how we use quantity information to make sense of the world."

Lourenco recently received a grant of $300,000 from the John Merck Fund, for young investors doing cognitive or biological science with implications for developmental disabilities. She plans to use it to further study how this system for processing quantitative information develops, both normally and in an atypical situation such as the learning disorder known as dyscalculia – the mathematical counterpart to dyslexia.

"Dyslexia has gotten a great deal of attention during the past couple of decades," Lourenco says. "But as our world keeps getting more technical, and students in the United States lag other countries in math, more attention is being paid to the need to reason about numbers, space and time. I'd like to explore the underlying causes of dyscalculia and maybe get a handle on how to intervene with children who have difficulty engaging in quantitative reasoning."

(Photo: Carol Clark)

Emory University

WORLD'S OLDEST FIG WASP FOSSIL PROVES THAT IF IT WORKS, DON'T CHANGE IT

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The world's oldest known example of a fig wasp has been found on the Isle of Wight. The fossil wasp is almost identical to the modern species, proving that this tiny but specialised insect has remained virtually unchanged for over 34 million years.

The fossil isn't a new find but was wrongly identified as an ant when it was first discovered in the 1920s. Fig wasp expert at the University of Leeds, Dr Steve Compton, was called in to study the fossil when the late Dr Mikhail Kozlov spotted the mistake during research at the Natural History Museum, London into the flora and fauna of the Isle of Wight. The findings of Dr Compton and the team are published in the Royal Society journal Biology Letters.

"There were three very well-preserved specimens and we were able to use modern techniques to look at them in detail," says Dr Compton. "What makes this fossil fascinating is not just its age, but that it is so similar to the modern species. This means that the complex relationship that exists today between the fig wasps and their host trees developed more than 34 million years ago and has remained unchanged since then."

Fig wasps and fig trees are mutually dependent, with each of the 800 or so modern species of tree pollinated by just one or two species of fig wasp that ignore other fig trees. The wasps – which measure just 1.5mm in length – have developed a particular body shape and features to enable them to crawl into figs to reach the flowers there.

Using state of the art microscopy facilities at the Museum, Dr Compton's team compared the fossils with modern fig wasps and with an example in Dominican amber dated to 20 million years, which he had bought over the internet and has since donated to the Museum. Their findings show that both fossil insects had the same body shape and features as modern species.

Because fig wasp larvae do better if they feed within a pollinated flower, the most highly developed species of wasps actively pollinate the figs before laying their eggs, rather than passively spreading pollen as they move between trees. The wasps collect pollen in pockets on the underside of their bodies and then take it to another tree, where they pull it out and spread in on the flowers before laying their eggs.

The team found pollen pockets on the underside of the fossil wasp and the wasp in amber and, using scanning electron microscopy, identified grains of fig pollen within the pockets. This proves that active pollination was already achieved over 34 million years ago and has remained unchanged to this day.

The edible figs we eat today are produced on specialised female plants that trick the wasps into entering the figs and strip off their wings, but then prevent them from laying any eggs. As a result, the figs produce only seeds and no wasp offspring. The length of the ovipositor – the organ the wasp uses to lay its eggs – of the Isle of White fig wasp shows that its host fig tree had already evolved this method of cheating on its partner.

"We believe from molecular evidence that fig wasps and fig trees have been evolving together for over 60 million years," says Dr Compton. "Now we have fossil confirmation that gets us a bit closer to that date. Although we often think of the world as constantly changing, what this fossil gives us is an example of something remaining unchanged for tens of millions of years – something which in biology we call 'stasis'."

One of the major changes the fig and its wasp will have had to face – beyond obvious climatic differences that mean fig trees are no longer native to the Isle of Wight – is the range of animals that eat the fruit and spread its seeds. Figs are a major source of food in tropical forests and more birds and mammals feed on figs than on any other fruit – so it's reassuring to know that these plants and their pollinators have responded successfully to previous episodes of climate change.

(Photo: Simon van Noort, Iziko Museums of Cape Town, www.figweb.org)

University of Leeds

TINY INSECT BRAINS CAPABLE OF HUGE FEATS

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Insects may have tiny brains the size of a pinhead, but the latest research from the University of Adelaide shows just how clever they really are.

For the first time, researchers from the University's Discipline of Physiology have worked out how insects judge the speed of moving objects.

It appears that insect brain cells have additional mechanisms which can calculate how to make a controlled landing on a flower or reach a food source. This ability only works in a natural setting.

In a paper published in the international journal Current Biology, lead author David O'Carroll says insects have well identified brain cells dedicated to analysing visual motion, which are very similar to humans.

"It was previously not understood how a tiny insect brain could use multiple brain pathways to judge motion," Associate Professor O'Carroll says.

"We have known for many years that they can estimate the direction of moving objects but until now we have not known how they judge speed like other animals, including humans.

"It appears they take into account different light patterns in nature, such as a foggy morning or a sunny day, and their brain cells adapt accordingly.

"This mechanism in their brain enables them to distinguish moving objects in a wide variety of natural settings. It also highlights the fact that single neurons can exhibit extremely complex behaviour."

Assoc. Prof. O'Carroll co-authored the paper with Paul Barnett, a Physiology PhD student at the University of Adelaide, and Dr Karin Nördstrom, a former Physiology Postdoctoral Fellow at Adelaide who is now based at Uppsala University in Sweden.

Their specific research is focused on how the brain makes sense of the world viewed by the eye, using the insect visual system as an important model.

"Insects are ideal for our research because their visual system accounts for as much as 30% of their mass, far more than most other animals," Assoc. Prof. O'Carroll says.

His team is collaborating with industry to develop artificial eyes in robots, mimicking human and insect vision.

(Photo: Doekele Stavenga)

University of Adelaide

SHARKS CAN REALLY SNIFF OUT THEIR PREY, AND THIS IS HOW THEY DO IT

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It's no secret that sharks have a keen sense of smell and a remarkable ability to follow their noses through the ocean, right to their next meal. Now, researchers reporting online on June 10th in Current Biology, a Cell Press publication, have figured out how the sharks manage to keep themselves on course.

It turns out that sharks can detect small delays, no more than half a second long, in the time that odors reach one nostril versus the other, the researchers report. When the animals experience such a lag, they will turn toward whichever side picked up the scent first.

"The narrow sub-second time window in which this bilateral detection causes the turn response corresponds well with the swimming speed and odor patch dispersal physics of our shark species," known as Mustelus canis or the smooth dogfish, said Jayne Gardiner of the University of South Florida. All in all, it means that sharks pick up on a combination of directional cues, based on both odor and flow, to keep themselves oriented and ultimately find what they are looking for.

If a shark experiences no delay in scent detection or a delay that lasts too long—a full second or more—they are just as likely to make a left-hand turn as they are to make a right.

These results refute the popular notion that sharks and other animals follow scent trails based on differences in the concentration of odor molecules hitting one nostril versus the other. It seems that theory doesn't hold water when one considers the physics of the problem.

"There is a very pervasive idea that animals use concentration to orient to odors," Gardiner said. "Most creatures come equipped with two odor sensors—nostrils or antennae, for example—and it has long been believed that they compare the concentration at each sensor and then turn towards the side receiving the strongest signal. But when odors are dispersed by flowing air or water, this dispersal is incredibly chaotic."

Indeed, Gardiner explained, recent studies have shown that concentrations of scent molecules could easily mislead. Using dyes that light up under laser light, scientists found that there can be sudden peaks in the concentrations of molecules even at a distance from their source.

Gardiner's team suggests that the findings in the small shark species they studied may help to explain the evolution of the wide and flat heads that make hammerhead sharks so recognizable. One idea has held that the characteristic hammerhead may lend the animals a better sense of smell. But studies hadn't shown their noses to be all that remarkable, really. For instance, they don't respond to odors at concentrations lower than other sharks. The new findings suggest that the distance between their nostrils could be the key.

"If you consider an animal encountering an odor patch at a given angle, an animal with more widely spaced nostrils will have a greater time lag between the odor hitting the left and right nostrils than an animal with more closely spaced nostrils," Gardiner said. "Hammerheads may be able to orient to patches at a smaller angle of attack, potentially giving them better olfactory capabilities than pointy-nosed sharks." That's a theory that now deserves further testing.

In addition to giving insights into the evolution and behavior of sharks, the findings might also lead to underwater robots that are better equipped to find the source of chemical leaks, like the oil spill that is now plaguing the Gulf Coast, according to the researchers.

"This discovery can be applied to underwater steering algorithms," Gardiner said. "Previous robots were programmed to track odors by comparing odor concentrations, and they failed to function as well or as quickly as live animals. With this new steering algorithm, we may be able to improve the design of these odor-guided robots. With the oil spill in the Gulf of Mexico, the main oil slick is easily visible and the primary sources were easy to find, but there could be other, smaller sources of leaks that have yet to be discovered. An odor-guided robot would be an asset for these types of situations."

Cell Press

HEAVY METAL GLASS HELPS LIGHT GO THE DISTANCE

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The fiber optic cable networks linking the world are an essential part of modern life. To keep up with ever-increasing demands for more bandwidth, scientists are working to improve the optical amplifiers that boost fiber optic signals across long distances.

Optical amplifier research is focused on glass fibers doped with rare earth elements. The elements, such as erbium and ytterbium, amplify light signals when excited by a laser. Many different combinations of elements have been tried in pursuit of amplifiers operating in different communication wavebands. However, obtaining effective signal amplifications in those rare earth ions is challenging and requires advanced materials and manufacturing. And to be commercially useful, the glass must be both stable and low-loss, requiring a little energy to boost signals.

An experimental glass developed by a team from Dalian Polytechnic University in China and the City University of Hong Kong solves some of these manufacturing problems. The researchers incorporated heavy metal and alkali/alkaline earth elements such as lead, bismuth, gallium, lithium, potassium, and barium in an oxide glass doped with trivalent samarium rare earth ion. Among oxide glasses, the maximum phonon energy of these materials is nearly the lowest, which may induce multi-channel fluorescence emissions and obvious enhancement of quantum efficiencies of samarium ions.

During laboratory tests, the samarium glass released infrared energy at a wavelength of 1185 nanometers – within the window of fiber optical telecommunications – among other wavelengths. The results, reported in the Journal of Applied Physics, published by the American Institute of Physics (AIP), indicate adding samarium to heavy metal gallate glass is worth exploring for use in both fiber optic networks and lasers.

American Institute of Physics

DEAR DIARY, I'M LEAVING YOU FOR TWITTER: RESEARCHER FINDS OLD DIARY ENTRIES ARE AKIN TO TWEETS

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The day after Lee Humphreys, Cornell assistant professor of communication, presented her paper on the remarkable similarities between Twitter tweets and diary entries of the late 18th and early 19th centuries at a conference in Atlanta, a story about her work appeared on a Wall Street Journal blog. Two days later, the New Yorker magazine took note of her work.

The Twittersphere had scooped the story.

"We tend to think of new media as entirely new and different," said Humphreys, who has studied social media for five years. "But often we see people using new media for old problems that people have always had to think about and engage with."

In reviewing volumes of diaries, mostly written by women, Humphreys found many terse records about what was happening in daily life in the same style demanded by Twitter's 140-character limit. Many diary entries ranged, for example, from what was for dinner to reports of deaths, births, marriages and travel, such as "April 7. Mr. Fiske Buried. April 27. Made Mead. At the assembly," from the 1770 diary of Mary Vial Holyoke of Salem, Mass.

Diarists wrote under the constraints of small notebooks that allotted only a few lines per date entry, and some historians argue that diary writers -- who lived busy, stressful lives in a time when leisure existed only for the rich -- found such constraints freeing. Diaries of the era were intended to be semi-public documents to be shared with others, Humphreys said. The modern notion of confessional, reflective entries hadn't come into play.

"Our whole notion of privacy is a relatively modern phenomenon," she added. "You really don't get a sense of personal, individual self until the end of the 19th century, so it makes perfect sense that diaries or journals prior to that time were much more social in nature."

During the weeklong Computer Human Interaction conference where Humphreys presented her findings, the Library of Congress announced April 14 -- via Twitter -- that it would archive all public tweets tweeted since March 2006. This will include tweets from organizations and corporations that produce "a really interesting slice of cultural products ranging from the individual mom who's tweeting about her kids not going down for a nap to Starbucks or GM, who are using Twitter to promote their products and services and engage their customers."

"Tweets capture a moment in history in a really interesting way," Humphreys said. "You have everything from reports from the Iranian election to what people had for breakfast to Haiti relief. The whole spectrum of events is being chronicled through this technology, and the fact that it's public already represents a unique opportunity for the Library of Congress to include in its archive."

In researching Twitter messages for 18 months, Humphreys has been coding tweets, with the help of undergraduate research assistants, by content in such areas as work, health, home and religion, and will analyze the results over the summer.

"I'm in the process of getting a grant to study the privacy implications of Twitter as well as people's motivations, intentions and practices," Humphreys said. "We know Twitter tends to be used by urban, younger populations, so it's not representing everybody, and no culture can be reduced to the texts that it produces. So as great as it is to have these diaries and these tweets, we recognize them as incomplete representations of society. It's easy to see that with the diaries but it's just as important to see that with Twitter."

(Photo: Cornell U.)

Cornell University

AUTISM FINDING COULD LEAD TO SIMPLE URINE TEST FOR THE CONDITION

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Children with autism have a different chemical fingerprint in their urine than non-autistic children, according to new research published tomorrow in the print edition of the Journal of Proteome Research.

The researchers behind the study, from Imperial College London and the University of South Australia, suggest that their findings could ultimately lead to a simple urine test to determine whether or not a young child has autism.

Autism affects an estimated one in every 100 people in the UK. People with autism have a range of different symptoms, but they commonly experience problems with communication and social skills, such as understanding other people’s emotions and making conversation and eye contact.

People with autism are also known to suffer from gastrointestinal disorders and they have a different makeup of bacteria in their guts from non-autistic people.

Today's research shows that it is possible to distinguish between autistic and non-autistic children by looking at the by-products of gut bacteria and the body’s metabolic processes in the children's urine. The exact biological significance of gastrointestinal disorders in the development of autism is unknown.

The distinctive urinary metabolic fingerprint for autism identified in today's study could form the basis of a non-invasive test that might help diagnose autism earlier. This would enable autistic children to receive assistance, such as advanced behavioural therapy, earlier in their development than is currently possible.

At present, children are assessed for autism through a lengthy process involving a range of tests that explore the child's social interaction, communication and imaginative skills. Early intervention can greatly improve the progress of children with autism but it is currently difficult to establish a firm diagnosis when children are under 18 months of age, although it is likely that changes may occur much earlier than this.

The researchers suggest that their new understanding of the makeup of bacteria in autistic children's guts could also help scientists to develop treatments to tackle autistic people's gastrointestinal problems.

Professor Jeremy Nicholson, the corresponding author of the study, who is the Head of the Department of Surgery and Cancer at Imperial College London, said: "Autism is a condition that affects a person's social skills, so at first it might seem strange that there's a relationship between autism and what’s happening in someone's gut. However, your metabolism and the makeup of your gut bacteria reflect all sorts of things, including your lifestyle and your genes. Autism affects many different parts of a person's system and our study shows that you can see how it disrupts their system by looking at their metabolism and their gut bacteria.

"We hope our findings might be the first step towards creating a simple urine test to diagnose autism at a really young age, although this may be a long way off - such a test could take years to develop. We know that giving therapy to children with autism when they are very young can make a huge difference to their progress. A urine test might enable professionals to quickly identify children with autism and help them early on," he added.

The researchers are now keen to investigate whether metabolic differences in people with autism are related to the causes of the condition or are a consequence of its progression.

The researchers reached their conclusions by using H NMR Spectroscopy to analyse the urine of three groups of children aged between 3 and 9: 39 children who had previously been diagnosed with autism, 28 non-autistic siblings of children with autism, and 34 children who did not have autism who did not have an autistic sibling.

They found that each of the three groups had a distinct chemical fingerprint. Non-autistic children with autistic siblings had a different chemical fingerprint than those without any autistic siblings, and autistic children had a different chemical fingerprint than the other two groups.

(Photo: ICL)

Imperial College London

A RAINFOREST REVELATION

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Global warming may present a threat to animal and plant life even in biodiversity hot spots once thought less likely to suffer from climate change, according to a new study from Rice University.

Research by Amy Dunham, a Rice assistant professor of ecology and evolutionary biology, detailed for the first time a direct correlation between the frequency of El Niño and a threat to life in Madagascar, a tropical island that acts as a refuge for many unique species that exist nowhere else in the world. In this case, the lemur plays the role of the canary in the coal mine.

The study in the journal Global Change Biology is currently available online and will be included in an upcoming print issue.

Dunham said most studies of global warming focus on temperate zones. "We all know about the polar bears and their melting sea ice," she said. "But tropical regions are often thought of as refuges during past climate events, so they haven’t been given as much attention until recently.

"We're starting to realize that not only are these hot spots of biodiversity facing habitat degradation and other anthropogenic effects, but they're also being affected by the same changes we feel in the temperate zones."

Dunham's interest in lemurs, which began as an undergraduate student at Connecticut College, resulted in a groundbreaking study last year that provided new insight into a long-standing mystery: Why male and female lemurs are the same size.

This time, she set out to learn how El Niño patterns impact rainfall in southeastern Madagascar and how El Niño and cyclones affect the reproductive patterns of the Milne-Edwards' Sifaka lemur.

The lemur's mating habits are well-defined, which makes the animal a good candidate for such a study. Female lemurs are sexually responsive to males for only one day a year in the austral summer months of December or January and give birth six months later.

Dunham's co-authors -- Elizabeth Erhart and Patricia Wright -- have done behavioral studies of lemurs in Ranomafana, a national park in the southeastern rainforest of Madagascar, for 20 years. Erhart is an associate professor and assistant chair of the Department of Anthropology at Texas State University-San Marcos, and Wright is a professor of anthropology at Stony Brook University and director of the Institute for the Conservation of Tropical Environments.

"There aren't many species that have such long-term demographic data that enable us to look at these kinds of questions," Dunham said. "So this was a unique opportunity."

The warming of global sea temperatures may "enhance" El Niño cycles, according to the National Oceanic and Atmospheric Administration. Dunham found that in Ranomafana, contrary to expectations, El Niño makes wet seasons wetter. "When it rains heavily, lemurs are not active. They sit there and wait for the rain to stop, huddling for warmth," Dunham said. Anecdotal evidence suggested heavy rains knock fruit off the trees when lactating lemurs need it most, and may even kill trees outright.

Dunham learned from the data that cyclones making landfall have a direct negative effect on the fecundity – or potential reproductive capacity – of lemurs. The team also discovered that fecundity "was negatively affected when El Niño occurred in the period before conception, perhaps altering ovulation, or during the second six months of life, possibly reducing infant survival during weaning," they wrote.

"Madagascar's biodiversity is an ecological treasure," Dunham said. "But its flora and fauna already face extinction from rapid deforestation and exploitation of natural resources. The additional negative effects of climate change make conservation concerns even more urgent."

(Photo: Rice U.)

Rice University

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