DIAMOND IS ONE TOUGH COOKIE

Most people know that diamond is one of the hardest solids on Earth, so strong that it can easily cut through glass and steel. Surprisingly, very little is known about the strength of diamond at extreme conditions. But new research by Lawrence Livermore National Laboratory scientists shows that diamond becomes even stronger during rapid compression.

Using the Janus laser at LLNL and the Omega laser at the University of Rochester, Livermore scientists and Rochester and UC Berkeley colleagues showed that when shock waves are applied to diamond with powerful lasers, it can support almost a million times atmospheric pressure before being crushed.

The research has implications for the technological uses of diamond.

“It could also provide insights into the ancient history of natural diamonds found on Earth and in meteorites, where shock waves caused by impact are common,” said Stewart McWilliams, lead author of a paper appearing in the upcoming edition of the journal, Physical Review B.

McWilliams conducted the experiments as a graduate student at UC Berkeley while on a Student Employee Graduate Research Fellowship (SEGRF) at LLNL.

Most natural diamonds are formed at high-pressure, high-temperature conditions existing at depths of 87 to 120 miles in the Earth’s mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25 percent to 75 percent of the age of the Earth).

In the recent research, the team measured the behavior of natural diamond crystals under shock-wave compression between 1 million and 10 million atmospheres of pressure, and the diamonds were crushed and melted in just a nanosecond (one billionth of a second).

“What we found is that diamond exhibits considerable strength right up to the point it melts,” McWilliams said.

“We reached some surprising conclusions about the strength of diamond,” said LLNL co-author Jon Eggert. “This type of research informs us about the interiors of the gas giants as well our own planet.”

Earlier research conducted by Livermore scientists show that diamond melts at around 6 million atmospheres of pressure and 14,000 degrees Fahrenheit. Their experiments mimicked conditions on the icy gas giant planets (Uranus and Neptune) where, according to their research, icebergs of diamond could float on a sea of liquid carbon.

(Photo: Eugene Kowaluk/LLE)

Lawrence Livermore National Laboratory

RECOGNITION OF FACIAL EXPRESSIONS IS NOT UNIVERSAL

Caucasians and Asians don't examine faces in the same way, according to new research. PhD student Caroline Blais, of the Université de Montréal Department of Psychology, has published two studies on the subject: one in Current Biology and the other in PLoS One.

Previous studies have shown that people collect information by mostly studying the eyes as well as the mouth of a face. "The problem is that these studies always used Caucasian test subjects," says Blais.

Questioning the universality of facial recognition began after studies showed that Asians study faces in an overall fashion, while Caucasians break down faces into distinct parts.

Blais used a camera designed to track eye movements to study 14 Caucasian and 14 Asian participants. As part of the experiment, subjects were shown 112 Caucasian and Asian faces and asked to report if they had seen the face before and to name the dominating trait. The study confirmed that Caucasians study the triangle of the eyes and mouth, while Asians focus on the nose.

Caucasian and Asian subjects excelled at recognizing someone of their race, yet both had the same level of difficulty in identifying someone of another ethnic group. According to Blais, this says more about the analytical approach of Caucasians and the holistic approach of Asians.

In a second experiment, test subjects had to pinpoint an emotion: surprise, fear, disgust or joy. Asians mostly focused on the eyes and not enough on the mouth, which meant some emotions were wrongly identified.

"Asians had particular problems with negative emotions. They confused fear and surprise as well as disgust and anger," says Blais. "This is because they avoided looking at the mouth which provides a lot of information about these emotions."

Cultural or biological causes, Blais says, might explain why humans don't read faces in a universal fashion.

(Photo: Université de Montréal)

Université de Montréal

A GIMMICK-FREE WEIGHT-LOSS PILL IN THE WORKS

A Université de Montréal research team is developing a pill composed of leptin, the protein that tells our brain to stop eating.

"Mice deprived of leptin will not stop eating. They become so big they have trouble moving around," says Moïse Bendayan, a pathology professor at the Université de Montréal Faculty of Medicine who has studied the leptin protein extensively.

Leptin regulates appetite in mammals and its levels decrease when fasting and rise during meals. It has been proven to be an appetite suppressant when administered intravenously to pathologically obese people.

Postdoctoral student Philippe Cammisotto is leading the charge for a leptin-based, appetite suppressing pill with Dr. Bendayan and Émile Levy, a professor from the Department of Nutrition. "Taken orally, such a pill would provide obese people with the sensation of being full. They would eat less and in turn lose weight," says Dr. Cammisotto.

"We hope to start animal testing in 2010," says Bendayan. "The molecule is easy to synthesize and the protocol is ready."

After decades of building his reputation in fundamental research, Bendayan is happy to collaborate on something more tangible. "Obesity is a big problem in our society, no pun intended," says Bendayan. "To develop medication to combat obesity would be a great way for our laboratory to contribute to public health."

The new pill is being created based on a startling Université de Montréal discovery from 2006: leptin isn't only secreted by fatty tissues. "From the first bite of any meal, leptin levels skyrocket in the bloodstream. Yet this has nothing to do with the leptin stored in the fatty tissues," says Bendayan. "In the lab, we proved that up to 80 percent of cells in our stomach also produce leptin. Those are the ones that regulate appetite."

The Université de Montréal finding led to a different understanding of how the protein works, since leptin alone can't survive in an acidic stomach without assistance. Indeed, leptin protects itself with an accomplice that acts as its bodyguard and accompanies the protein through the digestive system until it can be absorbed into the bloodstream.

(Photo: Université de Montréal)

Université de Montréal

LOST ROMAN LAW CODE DISCOVERED IN LONDON

Part of an ancient Roman law code previously thought to have been lost forever has been discovered by researchers at UCL's Department of History. Simon Corcoran and Benet Salway made the breakthrough after piecing together 17 fragments of previously incomprehensible parchment. The fragments were being studied at UCL as part of the Arts & Humanities Research Council-funded "Projet Volterra" – a ten year study of Roman law in its full social, legal and political context.

Corcoran and Salway found that the text belonged to the Codex Gregorianus, or Gregorian Code, a collection of laws by emperors from Hadrian (AD 117-138) to Diocletian (AD 284-305), which was published circa AD 300. Little was known about the codex's original form and there were, until now, no known copies in existence.

"The fragments bear the text of a Latin work in a clear calligraphic script, perhaps dating as far back as AD 400," said Dr Salway. "It uses a number of abbreviations characteristic of legal texts and the presence of writing on both sides of the fragments indicates that they belong to a page or pages from a late antique codex book - rather than a scroll or a lawyer's loose-leaf notes.

"The fragments contain a collection of responses by a series of Roman emperors to questions on legal matters submitted by members of the public," continued Dr Salway. "The responses are arranged chronologically and grouped into thematic chapters under highlighted headings, with corrections and readers' annotations between the lines. The notes show that this particular copy received intensive use."

The surviving fragments belong to sections on appeal procedures and the statute of limitations on an as yet unidentified matter. The content is consistent with what was already known about the Gregorian Code from quotations of it in other documents, but the fragments also contain new material that has not been seen in modern times.

"These fragments are the first direct evidence of the original version of the Gregorian Code," said Dr Corcoran. "Our preliminary study confirms that it was the pioneer of a long tradition that has extended down into the modern era and it is ultimately from the title of this work, and its companion volume the Codex Hermogenianus, that we use the term 'code' in the sense of 'legal rulings'."

This particular manuscript may originate from Constantinople (modern Istanbul) and it is hoped that further work on the script and on the ancient annotations will illuminate more of its history.

(Photo: UCL)

University College London

IS THE HOBBIT'S BRAIN UNFEASIBLY SMALL?

Homo floresiensis, a pygmy-sized small-brained hominin popularly known as 'the Hobbit' was discovered five years ago, but controversy continues over whether the small brain is actually due to a pathological condition. How can its tiny brain size be explained? Researchers writing in the open access journal BMC Biology have tackled this question in the context of a comprehensive assessment of the evolution of brain and body size throughout the larger primate family.

Nick Mundy and Stephen Montgomery, from the Department of Zoology at Cambridge University, UK, and colleagues from Durham University used previously published data from living and extinct species to reconstruct the pattern of brain and body mass evolution in primates. According to Nick Mundy, "Our results provide robust confirmation for the suggestion that strong evolutionary trends have governed the expansion of the primate brain. In contrast, body size evolution has not tended to increase in primates, implying brain and body mass have been subject to separate selection pressures and supporting the findings of previous studies in other taxonomic groups that these two highly correlated traits can show differences in their patterns of evolution".

Brain expansion began early in primate evolution and has occurred in all major groups, suggesting a strong selective advantage to increased brainpower in most primate lineages. Despite this overall trend, however, Mundy and his colleagues have identified several branches/lineages within each major group that have shown decreasing brain and body mass as they evolve, for example in marmosets and mouse lemurs. According to Mundy, "We find that, under reasonable assumptions, the reduction in brain size during the evolution of Homo floresiensis is not unusual in comparison to these other primates. Along with other recent studies on the effects of 'island dwarfism' in other mammals, these results support the hypothesis that the small brain of Homo floresiensis was adapted to local ecological conditions on Flores."

(Photo: Professor Peter Brown, University of New England)

BioMed Central

WHY HUMANS OUTLIVE APES

The same evolutionary genetic advantages that have helped increase human lifespans also make us uniquely susceptible to diseases of aging such as cancer, heart disease and dementia, reveals a study to be published in a special PNAS collection on "Evolution in Health and Medicine" on Tuesday, Jan. 26.

Comparing the life spans of humans with other primates, Caleb Finch, ARCO & William F. Kieschnick Professor in the Neurobiology of Aging in the USC Davis School of Gerontology, explains that slight differences in DNA sequencing in humans have enabled us to better respond to infection and inflammation, the leading cause of mortality in wild chimpanzees and in early human populations with limited access to modern medicine.

Specifically, humans have evolved what Finch calls "a meat-adaptive gene" that has increased the human lifespan by regulating the effects of meat-rich diets. ApoE3 is unique to humans and is a variant of the cholesterol transporting gene, apolipoprotein E, which regulates inflammation and many aspects of aging in the brain and arteries.

"Over time, ingestion of red meat, particularly raw meat infected with parasites in the era before cooking, stimulates chronic inflammation that leads to some of the common diseases of aging," Finch said.

However, another expression of apolipoprotein E in humans -- the minor allele, apoE4 -- can increase the risk of heart disease and Alzheimer's disease by several-fold, Finch explained. ApoE4 carriers have higher totals of blood cholesterol, more oxidized blood lipids and higher rates of early onset coronary heart disease and Alzheimer's disease.

"The chimpanzee apoE functions more like the "good" apoE3, which contributes to low levels of heart disease and Alzheimer's," Finch said. Chimpanzees in captivity have unusually low levels of heart disease and Alzheimer-like changes during aging when compared to humans.

Finch hypothesizes that the expression of ApoE4 in humans could be the result of the "antagonistic pleiotropy theory" of aging, in which genes selected to fight diseases in early life have adverse affects in later life.

"ApoeE may be a prototype for other genes that enabled the huge changes in human lifespan, as well as brain size, despite our very unape-like meat-rich diets," Finch said. "Drugs being developed to alter activities of apoE4 may also enhance lifespan of apoE4 carriers."

In spite of their genetic similarity to humans, chimpanzees and great apes have maximum lifespans that rarely exceed 50 years. Even in high-mortality modern hunter-forager populations, human life expectancy at birth is still twice that of wild chimpanzees.

University of Southern California