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Friday, January 30, 2015

New App Monitors Mental Health Through “Selfie” Videos, Social Media

Researchers at the University of Rochester have developed an innovative approach to turn any computer or smartphone with a camera into a personal mental health monitoring device.

In a paper to be presented this week at the American Association for Artificial Intelligence conference in Austin, Texas, Professor of Computer Science Jiebo Luo and his colleagues describe a computer program that can analyze "selfie" videos recorded by a webcam as the person engages with social media.


Apps to monitor people's health are widely used, from monitoring the spread of the flu to providing guidance on nutrition and managing mental health issues. Luo explains that his team's approach is to "quietly observe your behavior" while you use the computer or phone as usual. He adds that their program is "unobtrusive; it does not require the user to explicitly state what he or she is feeling, input any extra information, or wear any special gear." For example, the team was able to measure a user's heart rate simply by monitoring very small, subtle changes in the user's forehead color. The system does not grab other data that might be available through the phone - such as the user's location.

The researchers were able to analyze the video data to extract a number of "clues," such as heart rate, blinking rate, eye pupil radius, and head movement rate. At the same time, the program also analyzed both what the users posted on Twitter, what they read, how fast they scrolled, their keystroke rate and their mouse click rate. Not every input is treated equally though: what a user tweets, for example, is given more weight than what the user reads because it is a direct expression of what that user is thinking and feeling.

To calibrate the system and generate a reaction they can measure, Luo explained, he and his colleagues enrolled 27 participants in a test group and "sent them messages, real tweets, with sentiment to induce their emotion." This allowed them to gauge how subjects reacted after seeing or reading material considered to be positive or negative.

They compared the outcome from all their combined monitoring with the users' self reports about their feelings to find out how well the program actually performs, and whether it can indeed tell how the user feels. The combination of the data gathered by the program with the users' self-reported state of mind (called the ground truth) allows the researchers to train the system. The program then begins to understand from just the data gathered whether the user is feeling positive, neutral or negative.

Their program currently only considers emotions as positive, neutral or negative. Luo says that he hopes to add extra sensitivity to the program by teaching it to further define a negative emotion as, for example, sadness or anger. Right now, this is a demo program they have created and no "app" exists, but they have plans to create an app that would let users be more aware of their emotional fluctuations and make adjustments themselves.

Luo understands that this program and others that aim to monitor an individual's mental health or well-being raise ethical concerns that need to be considered. He adds that using this system means "effectively giving this app permission to observe you constantly," but adds that the program is designed for the use of the user only and does not share data with anyone else unless otherwise designated by the user.



Contacts and sources:
by Leonor Sierra
University of Rochester

Luo's co-authors on the paper, "Tackling Mental Health by Integrating Unobtrusive Multimodal Sensing," are Dawei Zhou, Vincent Silenzio, Yun Zhou, Glenn Currier, and Henry Kautz. The 29th AAAI Conference on Artificial Intelligence (AAAI) takes place in Austin, Texas, from Jan. 25-30, 2015.

Could A New Proposed Particle Help To Detect Dark Matter?

Researchers at the University of Southampton have proposed a new fundamental particle which could explain why no one has managed to detect 'Dark Matter', the elusive missing 85 per cent of the Universe's mass.

Dark Matter is thought to exist because of its gravitational effects on stars and galaxies, gravitational lensing (the bending of light rays) around these, and through its imprint on the Cosmic Microwave Background (the afterglow of the Big Bang).

Credit: University of Southampton

Despite compelling indirect evidence and considerable experimental effort, no one has managed to detect Dark Matter directly. Particle physics gives us clues to what Dark Matter might be, and the standard view is that Dark Matter particles have a very large mass for fundamental particles, comparable to that of heavy atoms. Lighter Dark Matter particles are considered less likely for astrophysical reasons, although exceptions are known, and this research highlights a previously unknown window where they could exist and, with very general arguments from particle physics, derives some surprising results.

The research is published in Scientific Reports.

The proposed particle has a mass of 100eV/c^2, only about 0.02 per cent that of an electron. While it does not interact with light, as required for Dark Matter, it does interact surprisingly strongly with normal matter. Indeed, in stark contrast to other candidates, it may not even penetrate Earth's atmosphere. Earth-bound detection is therefore not likely, so the researchers plan to incorporate searches into a space experiment planned by the Macroscopic quantum resonators (MAQRO) consortium, with whom they are already involved. A nanoparticle, suspended in space and exposed directly to the flow of Dark Matter, will be pushed downstream and sensitive monitoring of this particle's position will reveal information about the nature of this Dark Matter particle, if it exists.

Dark matter is invisible. Based on the effect of gravitational lensing, a ring of dark matter has been detected in this image of a galaxy cluster (CL0024+17) and is represented in blue
 Credit: NASA, ESA, M.J. Jee and H. Ford (Johns Hopkins University)

Dr James Bateman, from Physics and Astronomy at the University of Southampton and co-author of the study, says: "This work brings together some very different areas of physics: theoretical particle physics, observational x-ray astronomy, and experimental quantum optics. Our candidate particle sounds crazy, but currently there seem to be no experiments or observations which could rule it out. Dark Matter is one of the most important unsolved problems in modern physics, and we hope that our suggestion will inspire others to develop detailed particle theory and even experimental tests."

Dr Alexander Merle, co-author from the Max Planck Institute in Munich, Germany, adds: "At the moment, experiments on Dark Matter do not point into a clear direction and, given that also the Large Hadron Collider at CERN has not found any signs of new physics yet, it may be time that we shift our paradigm towards alternative candidates for Dark Matter. More and more particle physicists seem to think this way, and our proposal seems to be a serious competitor on the market."

Dark Matter may be a problem to be understood by crossing fields and looking for hidden possibilities.

Dr Bateman adds: "Also from this point of view, the paper comprises a milestone on the history of our department: for the first time there has been a publication involving authors from all three groups in Physics and Astronomy, which shows how valuable it can be to cross boundaries and to look beyond one's own field."


Contacts and sources: 
University of Southampton

CAT Scan Of Nearby Supernova Remnant Reveals Frothy Interior

Cassiopeia A, or Cas A for short, is one of the most well studied supernova remnants in our galaxy. But it still holds major surprises. Harvard-Smithsonian and Dartmouth College astronomers have generated a new 3-D map of its interior using the astronomical equivalent of a CAT scan. They found that the Cas A supernova remnant is composed of a collection of about a half dozen massive cavities - or "bubbles."

This composite image shows two perspectives of a three-dimensional reconstruction of the Cassiopeia A supernova remnant. This new 3-D map provides the first detailed look at the distribution of stellar debris following a supernova explosion. Such 3-D reconstructions encode important information for astronomers about how massive stars actually explode. The blue-to-red colors correspond to the varying speed of the emitting gas along our line of sight. The background is a Hubble Space Telescope composite image of the supernova remnant.
D. Milisavljevic (CfA) & R. Fesen (Dartmouth). Background image: NASA, ESA, and the Hubble Heritage Team.

"Our three-dimensional map is a rare look at the insides of an exploded star," says Dan Milisavljevic of the Harvard-Smithsonian Center for Astrophysics (CfA). This research is being published in the Jan. 30 issue of the journal Science.

About 340 years ago a massive star exploded in the constellation Cassiopeia. As the star blew itself apart, extremely hot and radioactive matter rapidly streamed outward from the star's core, mixing and churning outer debris. The complex physics behind these explosions is difficult to model, even with state-of-the-art simulations run on some of the world's most powerful supercomputers. However, by carefully studying relatively young supernova remnants like Cas A, astronomers can investigate various key processes that drive these titanic stellar explosions.

A photograph of Cas A from NASA's Chandra X-ray Observatory reveals the supernova remnant's complex structure. In this representative-color image low-energy X-rays are red, medium-energy ones are green, and the highest-energy X-rays detected by Chandra are colored blue.
Credit:  NASA/CXC/SAO 

"We're sort of like bomb squad investigators. We examine the debris to learn what blew up and how it blew up," explains Milisavljevic. "Our study represents a major step forward in our understanding of how stars actually explode."

To make the 3-D map, Milisavljevic and co-author Rob Fesen of Dartmouth College examined Cas A in near-infrared wavelengths of light using the Mayall 4-meter telescope at Kitt Peak National Observatory, southwest of Tucson, AZ. Spectroscopy allowed them to measure expansion velocities of extremely faint material in Cas A's interior, which provided the crucial third dimension.

They found that the large interior cavities appear to be connected to - and nicely explain - the previously observed large rings of debris that make up the bright and easily seen outer shell of Cas A. The two most well-defined cavities are 3 and 6 light-years in diameter, and the entire arrangement has a Swiss cheese-like structure.

The bubble-like cavities were likely created by plumes of radioactive nickel generated during the stellar explosion. Since this nickel will decay to form iron, Milisavljevic and Fesen predict that Cas A's interior bubbles should be enriched with as much as a tenth of a solar mass of iron. This enriched interior debris hasn't been detected in previous observations, however, so next-generation telescopes may be needed to find the "missing" iron and confirm the origin of the bubbles.

The researchers have posted an interactive version of their 3-D map online at https://www.cfa.harvard.edu/~dmilisav/casa-webapp/.



Contacts and sources: 
Christine Pulliam  
Harvard-Smithsonian Center for Astrophysics 

Some Potentially Habitable Planets Began As Gaseous, Neptune-Like Worlds

Two phenomena known to inhibit the potential habitability of planets -- tidal forces and vigorous stellar activity -- might instead help chances for life on certain planets orbiting low-mass stars, University of Washington astronomers have found.

In a paper published this month in the journal Astrobiology, UW doctoral student Rodrigo Luger and co-author Rory Barnes, research assistant professor, say the two forces could combine to transform uninhabitable "mini-Neptunes" -- big planets in outer orbits with solid cores and thick hydrogen atmospheres -- into closer-in, gas-free, potentially habitable worlds.

Strong irradiation from the host star can cause planets known as mini-Neptunes in the habitable zone to shed their gaseous envelopes and become potentially habitable worlds.
Credit; Rodrigo Luger / NASA images

Most of the stars in our galaxy are low-mass stars, also called M dwarfs. Smaller and dimmer than the sun, with close-in habitable zones, they make good targets for finding and studying potentially habitable planets. Astronomers expect to find many Earthlike and "super-Earth" planets in the habitable zones of these stars in coming years, so it's important to know if they might indeed support life.

Super-Earths are planets greater in mass than our own yet smaller than gas giants such as Neptune and Uranus. The habitable zone is that swath of space around a star that might allow liquid water on an orbiting rocky planet's surface, perhaps giving life a chance.

"There are many processes that are negligible on Earth but can affect the habitability of M dwarf planets," Luger said. "Two important ones are strong tidal effects and vigorous stellar activity."

A tidal force is a star's gravitational tug on an orbiting planet, and is stronger on the near side of the planet, facing the host star, than on the far side, since gravity weakens with distance. This pulling can stretch a world into an ellipsoidal or egglike shape as well as possibly causing it to migrate closer to its star.

"This is the reason we have ocean tides on Earth, as tidal forces from both the moon and the sun can tug on the oceans, creating a bulge that we experience as a high tide," Luger said. "Luckily, on Earth it's really only the water in the oceans that gets distorted, and only by a few feet. But close-in planets, like those in the habitable zones of M dwarfs, experience much stronger tidal forces."

This stretching causes friction in a planet's interior that gives off huge amounts of energy. This can drive surface volcanism and in some cases even heat the planet into a runaway greenhouse state, boiling away its oceans, and all chance of habitability.

Vigorous stellar activity also can destroy any chance for life on planets orbiting low-mass stars. M dwarfs are very bright when young and emit lots of high-energy X-rays and ultraviolet radiation that can heat a planet's upper atmosphere, spawning strong winds that can erode the atmosphere away entirely. In a recent paper, Luger and Barnes showed that a planet's entire surface water can be lost due to such stellar activity during the first few hundred million years following its formation.

"But things aren't necessarily as grim as they may sound," Luger said. Using computer models, the co-authors found that tidal forces and atmospheric escape can sometimes shape planets that start out as mini-Neptunes into gas-free, potentially habitable worlds.

How does this transformation happen?

Mini-Neptunes typically form far from their host star, with ice molecules joining with hydrogen and helium gases in great quantity to form icy/rocky cores surrounded by massive gaseous atmospheres.

"They are initially freezing cold, inhospitable worlds," Luger said. "But planets need not always remain in place. Alongside other processes, tidal forces can induce inward planet migration." This process can bring mini-Neptunes into their host star's habitable zone, where they are exposed to much higher levels of X-ray and ultraviolet radiation.

This can in turn lead to rapid loss of the atmospheric gases to space, sometimes leaving behind a hydrogen-free, rocky world smack dab in the habitable zone. The co-authors call such planets "habitable evaporated cores."

"Such a planet is likely to have abundant surface water, since its core is rich in water ice," Luger said. "Once in the habitable zone, this ice can melt and form oceans," perhaps leading to life.

Barnes and Luger note that many other conditions would have to be met for such planets to be habitable. One is the development of an atmosphere right for creating and recycling nutrients globally.

Another is simple timing. If hydrogen and helium loss is too slow while a planet is forming, a gaseous envelope would prevail and a rocky, terrestrial world may not form. If the world loses hydrogen too quickly, a runaway greenhouse state could result, with all water lost to space.

"The bottom line is that this process -- the transformation of a mini-Neptune into an Earthlike world -- could be a pathway to the formation of habitable worlds around M dwarf stars," Luger said.

Will they truly be habitable? That remains for future research to learn, Luger said.

"Either way, these evaporated cores are probably lurking out there in the habitable zones of these stars, and many may be discovered in the coming years."



Contacts and sources:
Peter Kelley

A Rare Glimpse At The Elusive Saharan Cheetah


Research by scientists and conservationists from the Wildlife Conservation Society, the Zoological Society of London, and other groups published this week in PLOS ONE shows that critically endangered Saharan cheetahs exist at incredibly low densities and require vast areas for their conservation. The research also offers some of the world's only photographs of this elusive big cat

Research by scientists and conservationists from the Wildlife Conservation Society, the Zoological Society of London, and other groups published today in PLOS ONE shows that critically endangered Saharan cheetahs exist at incredibly low densities and require vast areas for their conservation. The research also offers some of the world's only photographs of this elusive big cat.

Credit: Farid Belbachir/ZSL/OPNA

The findings are a result of the monitoring of Saharan cheetahs, a critically endangered cheetah subspecies, in Ahaggar Cultural Park, Algeria. Remote infra-red camera traps were used and the photographs gathered have provided the world's scientific community with some of the only close-up photographs ever taken of the Saharan cheetah. There are thought to be fewer than 250 of these animals left in the Sahara, making them one of the rarest carnivores on the planet.

The findings by scientists and conservationists at WCS, ZSL, University College London, UK, and Université de Béjaïa, Algeria, in collaboration with the Office National du Parc Culturel de l'Ahaggar, show that the Saharan cheetah adapts its behavior to cope with the harsh desert environment in which it lives. They are active at night, probably to avoid heat or contact with humans, and must cover a vast amount of ground to find prey.

Research into how cheetahs survive within extreme desert conditions gives scientists a better understanding of how best to approach their conservation. The survival of large carnivores within the Sahara desert indicates that at present the Ahaggar Cultural Park is still a relatively healthy habitat; however there are threats to cheetah and their prey. Authors argue that more needs to be done to secure this habitat's long-term survival.

Farid Belbachir, lead-author from Laboratoire d'Ecologie et Environnement, Université de Béjaïa, Algeria, said: "This is the first time we have been able to collect scientific data on the rare Saharan cheetah, as in the past we have had to rely on anecdotes and guesswork. We hope that this important carnivore does not follow the path to extinction like other Algerian desert species such as the addax antelope and dama gazelle."

Dr Sarah Durant, co-author from WCS and ZSL, added: "This research provides us with important new insights into the world of this remarkable desert-dwelling large cat. I hope that it not only provides invaluable scientific information about the ecology of the Saharan cheetah for the first time but also reminds the world of the value of studying and protecting desert species and their environments, which are often overlooked by researchers and conservation programs."

Confined to desert environments, the Saharan cheetah lives in pockets of north and west Africa. The report shows that Saharan cheetahs are more nocturnal, more wide-ranging and occur at lower densities than other cheetahs living in Africa.


Contacts and sources: 
John Delaney

Love And Intimacy In Later Life -- New Study Reveals Active Sex Lives Of The Over 70s

Older people are continuing to enjoy active sex lives well into their seventies and eighties, according to new research from The University of Manchester and NatCen Social Research.

More than half (54%) of men and almost a third (31%) of women over the age of 70 reported they were still sexually active, with a third of these men and women having frequent sex - meaning at least twice a month - according to data from the latest wave of the English Longitudinal Study of Ageing (ELSA).

Credit: University of Manchester

The paper, lead authored by Dr. David Lee, an Age UK Research Fellow at The University of Manchester's School of Social Sciences and entitled Sexual health and wellbeing among older men and women in England, is published in the American academic journal, Archives of Sexual Behavior.

It is the first study on sexual health of its kind to include people over the age of 80 and uncovers a detailed picture of the sex lives of older men and women in England, finding that a sizeable minority remain sexually active in their old age.

Contrary to popular misconceptions, it finds that overall health and conflicting partnership factors were more closely linked to decreasing sexual activity and functioning, rather than simply increasing age.

Of the more than 7000 people who responded to the questionnaire, very few (less than 3%) declined to answer direct questions about their sexual activities and problems.

Dr Lee said: "This is the first nationally-representative study to include people over the age of 80 when asking older men and women in England about their sexual health.

"We hope our findings improve public health by countering stereotypes and misconceptions about late-life sexuality, and offer older people a reference against which they may relate their own experiences and expectations.

"Our ongoing research is also highlighting the diversity of late-life sexualities, and trying to impose youthful norms of sexual health on older people would be over-simplistic and even unhelpful.

"It is however important that health professionals act on this and are more open about discussing sexual health with older people - it can't simply be assumed to be an irrelevance."

Problems most frequently reported by sexually active women related to becoming sexually aroused (32%) and achieving orgasm (27%), while for men it was erectile difficulties (39%).

Chronic health conditions and poor self-rated health seemed to have more obvious negative impacts on the sexual health of men compared to women.

Men were more concerned about their sexual activities and function than women and, with increasing age, these concerns tended to become more common. Sexually active women were less dissatisfied with their overall sex lives than men, and also reported decreasing levels of dissatisfaction with increasing age.

The study also found that many septuagenarians and octogenarians were still affectionate towards their partners, with 31% of men and 20% of women reporting frequent kissing or petting. Among those who reported any sexual activity in the past three months, 1% of men and 10% of women reported they felt obligated to have sex.

Caroline Abrahams, Charity Director at Age UK, said: "The fact this is the first time that people over 80 years old have been included in this kind of research highlights how often the public health needs of older people, including sexual health, are ignored or overlooked.

"With an ageing population it is important that providers of sexual health services understand the needs of older people in both clinical settings and when developing information and advice. These recent findings now need to be used to improve sexual health advice and information for older people."


Contacts and sources:
Deborah Linton
University of Manchester

Why Is A Dolphin Not A Cat? How Repurposing Non-Coding Elements In The Genome Gave Rise To The Great 'Mammalian Radiation'


New research shows how evolution has given rise to a rich diversity of species by repurposing functional elements shared by all mammals. Published in Cell by scientists at the European Bioinformatics Institute (EMBL-EBI) and the University of Cambridge Cancer Research UK-Cambridge Institute (CRUK CI), the study demonstrates how methods for understanding human biology can be used to understand a broad range of species.

Exploring gene regulation in 20 mammals provides insights into the mammalian radiation that occurred over 100 million years ago.

Credit:   Spencer Phillips, EMBL-EBI

Mammals all share a common ancestor, and they share a lot of the same genes. So what exactly makes a dolphin not a cat, and how did we all start to diverge from one another millions of years ago? Part of the answer lies in how - and when - genes are regulated. This latest research explores the evolution of gene regulation in 20 mammalian species, and provides deep insights into the 'mammalian radiation', a time of rapid morphological evolution that occurred shortly after the asteroid impact that caused the extinction of the dinosaurs.

Leveraging findings from a study comparing the genome sequences of 29 mammals, and with the help of conservation organisations such as the UK Cetacean Strandings Investigation Programme and the Copenhagen Zoo, the team were able to study and compare gene regulation in liver cells from 20 key species including the naked mole rat, human, Tasmanian devil, dolphin and sei whale.

"What we've shown is that evolution repurposes things that exist in all species, to make each species unique," explains Paul Flicek, head of Vertebrate Genomics at EMBL-EBI. "By looking at gene promoters and enhancers in many different mammals, we demonstrated that species-specific enhancers come from ancient DNA - that evolution captures DNA that's been around for a long time, and uses it for gene regulation in specific tissues."

Evolution has two ways to turn changes in the genome into differences between species: it can change a protein sequence, or it can change the way promoters or enhancers control that protein's expression. Today's study also shows that in some cases evolution uses both strategies at once. When amino acid sequences evolve very quickly, important regulation changes occur at the same time: the protein-coding sequence and the corresponding regulatory sequence change synergistically.

Gathering the samples - the experimental efforts were led by Diego Villar of CRUK CI - took well over two years, and the experiments themselves produced a staggering volume of data. Analysing the results brought the team to a new frontier in bioinformatics.

"People spend a lot of time and money trying to understand human biology, so most of the tools we have are designed to study human genomes," explains Camille Berthelot of EMBL-EBI, who led the computational work. "The reference data we have for the less studied species, like the Sei whale or Tasmanian devil, are nothing like the pored-over datasets we have for the human genome. A lot of what we did involved benchmarking, and making sure the methods and algorithms were fit for this kind of comparison."

"What inspired this work was a desire to get on top of the mountain, look out and see what is going on in the landscape of molecular evolution across the breadth of mammalian space," says Duncan Odom of CRUK CI and Wellcome Trust Sanger Institute. "What's exciting about this study is that we now know we can start to answer questions about the functional genetics of many under-explored species - questions we usually can ask only of humans and mice. We can use tools developed to study humans to understand the biology of all kinds of animals, whether they're blackbirds or elephants, and explore their relationship with one another. This research has given us new insights into mammalian evolution, and proven how powerful these methods can be."



Contacts and sources:
Mary Todd Bergman
European Molecular Biology Laboratory

Green Tea Compound Kills Oral Cancer Cells, Leaves Healthy Cells Along

A compound found in green tea may trigger a cycle that kills oral cancer cells while leaving healthy cells alone, according to Penn State food scientists. The research could lead to treatments for oral cancer, as well as other types of cancer.

Credit: Wikipedia

Earlier studies had shown that epigallocatechin-3-gallate -- EGCG -- a compound found in green tea, killed oral cancer cells without harming normal cells, but researchers did not understand the reasons for its ability to target the cancer cells, said Joshua Lambert, associate professor of food science and co-director of Penn State's Center for Plant and Mushroom Foods for Health. The current study shows that EGCG may trigger a process in the mitochondria that leads to cell death.

"EGCG is doing something to damage the mitochondria and that mitochondrial damage sets up a cycle causing more damage and it spirals out, until the cell undergoes programmed cell death," said Lambert. "It looks like EGCG causes the formation of reactive oxygen species in cancer cells, which damages the mitochondria, and the mitochondria responds by making more reactive oxygen species."

As this mitochondrial demise continues, the cancer cell also reduces the expression of anti-oxidant genes, further lowering its defenses.

"So, it's turning off its mechanism of protection at the same time that EGCG is causing this oxidative stress," Lambert added.

The EGCG did not cause this reaction in normal cells. In fact, it appeared to increase the protective capabilities of the cell, according to the researchers, who report their findings in the online issue of Molecular Nutrition and Food Research.

The appearance of green tea in three different stages (from left to right): the infused leaves, the dry leaves, and the liquid. Notice that the infused leaves look greener than the dry leaves.

Credit: Alessandro Martini /Wikipedia

The researchers studied normal human oral cells side-by-side with human oral cancer cells to determine how EGCG was affecting cancer cells differently than normal cells. They grew the normal and cancer cells on petri dishes and then exposed them to EGCG, the major polyphenol found in green tea, at concentrations typically found in the saliva after chewing green-tea chewing gum. At various times, the researchers would collect the cells and check for oxidative stress and signs of antioxidant response.

"We also took a lot of pictures, so we could use fluorescent dyes that measure mitochondrial function and oxidative stress and actually see these things develop," said Lambert, who worked with Jong-Yung Park, a research technician and Ling Tao, a doctoral candidate in food science.

The researchers said that a protein called sirtuin 3 -- SIRT3 -- is critical to the process.

"It plays an important role in mitochondrial function and in anti-oxidant response in lots of tissues in the body, so the idea that EGCG might selectively affect the activity of sirtuin 3 in cancer cells -- to turn it off -- and in normal cells -- to turn it on -- is probably applicable in multiple kinds of cancers," Lambert said.

The study builds on earlier research on how EGCG affected oral cancer, a disease that is expected to kill more than 8,000 people in the United States this year.

"We've published one paper previously just looking at the effect of these green tea polyphenols on oral cancer cells in cultures, and there have been other papers published using oral cancer cells and at least a couple of animal model studies that have looked at oral cancer and prevention of oral cancer," said Lambert.

He said the next step would be to study the mechanism in animals. If those tests and human trials are successful, the researchers then hope to create anti-cancer treatments that are as effective as current treatments without the harmful side effects.

"The problem with a lot of chemotherapy drugs -- especially early chemotherapy drugs -- is that they really just target rapidly dividing cells, so cancer divides rapidly, but so do cells in your hair follicles and cells in your intestines, so you have a lot of side effects," said Lambert. "But you don't see these sorts of side effects with green tea consumption."

The American Institute for Cancer Research supported this work.

Contacts and sources:
Matt Swayne
Penn State

Thursday, January 29, 2015

The Two Faces Of Mars: Moon-Sized Celestial Object Crashed Into The South Pole Of Mars

A moon-sized celestial object that crashed into the south pole of Mars: ETH geophysicists have conducted a three-dimensional simulation that shows for the first time how the Red Planet came to have two different hemispheres.

Mars has two differently shaped hemispheres: the lowlands of the northern hemisphere and the volcanic highlands (yellow to red regions) of the southern hemisphere. 
Credits: MOLA Science Team

The two hemispheres of Mars are more different from any other planet in our solar system. Non-volcanic, flat lowlands characterise the northern hemisphere, while highlands punctuated by countless volcanoes extend across the southern hemisphere. Although theories and assumptions about the origin of this so-called and often-discussed Mars dichotomy abound, there are very few definitive answers. ETH Zurich geophysicists with Giovanni Leone are now providing a new explanation. Leone is the lead author of a paper recently published in the journal Geophysical Research Letters.

Using a computer model, the scientists have concluded that a large celestial object must have smashed into the Martian south pole in the early history of the Solar System. Their simulation shows that this impact generated so much energy that it created a magma ocean, which would have extended across what is today’s southern hemisphere. The celestial body that struck Mars must have been at least one-tenth the mass of Mars to be able to unleash enough energy to create this magma ocean. The molten rock eventually solidified into the mountainous highlands that today comprise the southern hemisphere of Mars.

Volcanic activity stopped 3.5 billion years ago

In their simulation, the researchers assumed that the celestial body consisted to a large degree of iron, had a radius of at least 1,600 kilometres, and crashed into Mars at a speed of five kilometres per second. The event is estimated to have occurred around 4 to 15 million years after the Red Planet was formed. Mars’ crust must have been very thin at that time, like the hard, caramelised surface of a crème brûlée. And, just like the popular dessert, hiding beneath the surface was a liquid interior.

When the celestial object impacted, it added more mass to Mars, particularly iron. But the simulation also found that it triggered strong volcanic activity. Around the equator in particular, numerous mantle plumes were generated as a consequence of the impact, which migrated to the south pole where they ended. Mantle plumes are magma columns that transport liquid material from the mantle to the surface.

In the model, the researchers found that activity on Mars died down around 3.5 billion years ago, after which time the Red Planet experienced neither volcanic activity nor a magnetic field – this is consistent with observations and measurements.

3D simulation of an impact of an iron-rich celestial object on the southern pole of Mars.  
Image: from Leone et al. 2014

Earlier theories posited the opposite, namely that there must have been a gigantic impact or many smaller strikes against the northern hemisphere. The most important theory about the origin of the Mars dichotomy was formulated by two American researchers in 1984 in an article in the journalNature. They postulated that a large celestial object struck the Martian north pole. In 2008 a different team revived this idea and published it once again in Nature.

This theory did not convince Leone: “Our scenarios more closely reflect a range of observations about Mars than the theory of a northern hemisphere impact,” states Leone. The volcanoes on Mars are very unevenly distributed: they are common and widespread on the southern hemisphere, but are rare and limited to only a few small regions in the northern hemisphere. "Our model is an almost identical depiction of the actual distribution of volcanic identity,” asserts Leone. According to the researcher, no other model has been able to portray or explain this distribution before.

“Our simulation was also able to reproduce the different topographies of the two hemispheres in an nearly realistic manner,” says Leone. And he goes on to explain that the model – depending on the composition of the impact body chosen – is a virtually perfect representation of the size and shape of the hemispheres. One condition, however, is that the celestial body impacting Mars consist of 80 per cent iron; when the researchers simulated the impact with a celestial body made of pure silicate rock, the resulting image did not correspond to the reality of the dichotomy.

Magnetic field tipped the balance

Lastly, the model developed by the ETH researchers confirmed the date on which the magnetic field on Mars ceased to exist. The date calculated by the model corresponds to around 4.1 billion years ago, a figure previously proven by other scientists. The model also demonstrates why it ceased: a sharp decrease in heat flow from the core into the mantle and the crust in the first 400 million years after the impact. After a billion years, the heat flow was only one-tenth its initial value, which was too low to maintain even the volcanism. The model’s calculations closely match previous calculations and mineralogical explorations.

The volcanic activity is related to the heat flow, explains Leone, though the degree of volcanic activity could be varied in the simulation and influenced by the strength of the impact. This, he states, is in turn linked to the size and composition of the celestial object. In other words, the larger it is, the stronger the volcanic activity is. Nevertheless, after one billion years the volcanic vents were extinguished – regardless of the size of the impact.

It has become increasingly clear to Giovanni Leone that Mars has always been an extremely hostile planet, and he considers it almost impossible that it ever had oceans or even rivers of water. “Before becoming the cold and dry desert of today, this planet was characterised by intense heat and volcanic activity, which would have evaporated any possible water and made the emergence of life highly unlikely,” asserts the planet researcher.


Contacts and sources: 
Peter Rüegg
ETH Zurich


Citation: Leone G, Tackley PJ, Gerya TV, May DA, Zhu G (2014). Three-dimensional simulations of the southern polar giant impact hypothesis for the origin of the Martian dichotomy, Geophys. Res. Lett., 41, doi:10.1002/2014GL062261

Ancient Skull From Galilee Cave Offers Clues To The First Modern Europeans


The discovery of a 55,000-year-old partial skull in Northern Israel provides new insights into the migration of modern humans out of Africa. The rare find is reported in the journal Naturethis week by an international team of Israeli, North American and European researchers.

A key event in human evolution was the expansion of modern humans of African origin across Eurasia, replacing all other forms of hominin (humans and their predecessors), around 40,000-60,000 years ago. However, due to the scarcity of human fossils from this period, these ancestors of all present-day non-African modern populations have largely remained a mystery.

This is the interior of the Manot Cave in Israel's Galilee, where a 55,000-year-old skull sheds new light on modern human migration patterns.

Photo: Amos Frumkin / Hebrew University Cave Research Center)


Now, researchers describe a partial skull that dates to around 55,000, which was found at Manot Cave in Israel's Western Galilee. The Manot Cave was discovered in 2008 during construction activities that damaged its roof. Rock falls and active stalagmites had apparently blocked the initial entrance to the cave for at least 15,000 years. The Hebrew University of Jerusalem's Cave Research Center conducted an initial survey of the cave and reported the findings of archaeological remains.

Prof. Israel Hershkovitz of Tel Aviv University led the anthropological study of the skull, and led the excavation together with archaeologists Dr. Ofer Marder of Ben-Gurion University, and Dr. Omry Barzilai of the Israel Antiquities Authority.

This image shows inside the Manot Cave in Israel's Galilee, where a 55,000-year-old skull sheds new light on modern human migration patterns.

Photo: Amos Frumkin / Hebrew University Cave Research Center

The skull has a distinctive "bun"-shaped occipital region at the back. In this way its shape resembles modern African and European skulls, but differs from other anatomically modern humans from the Levant. This suggests that the Manot people could be closely related to the first modern humans that later colonized Europe.

The specimen also provides evidence that both modern humans and Neanderthals inhabited the southern Levant during the late Pleistocene, close in time to the likely interbreeding event between modern humans and Neanderthals.

Researchers from the Hebrew University played important roles in this discovery. Dating the skull at around 55,000 years is the graduate thesis work of Gal Yasur, a student at the Hebrew University's Earth Sciences Institute in the Faculty of Sciences. The dating work was done at the Geological Survey of Israel under the supervision of GSI Senior Scientists Dr. Miryam Bar-Matthews and Dr. Avner Ayalon, together with Prof. Alan Matthews, the Raymond F. Kravis Professor of Geology at the Hebrew University's Earth Sciences Institute. Prof. Amos Frumkin, Director of the Cave Research Center at the Hebrew University's Geography Department, researched the geological context of the skull in the Manot Cave. Ms. Mae Goder-Goldberger, a doctoral candidate at Hebrew University's Institute of Archaeology, is part of the archaeological team working in the cave.

This finding represents the first fossil evidence from the critical period when genetic and archaeological models predict that African modern humans successfully migrated out of Africa and colonized Eurasia. It also represents the first fossil evidence that during the late Middle Paleolithic, the Levant was occupied not only by Neanderthals but also by modern humans.

The researchers suggest that the population from which this skull is derived had recently migrated out of Africa and established itself in the Levantine corridor during a time span that was favorable for human migration, due to warmer and wetter climatic events over the Northern Sahara and the Mediterranean.




Contacts and sources:
Dov Smith
Hebrew University of Jerusalem

The research appears in the journal Nature under the title "Levantine cranium from Manot Cave (Israel) foreshadows the first European modern humans" (DOI 10.1038/nature14134).

The excavation at Manot Cave was initiated and supported throughout the years by the late Mr. Dan David, founder of the "Dan David Prize", and his son Mr. Ariel David. The ongoing research is financially supported by the Dan David Foundation, the Israel Antiquities Authority (IAA), Case Western Reserve University (CWRU), the Leakey Foundation, the Irene Levi Sala CARE Archaeological Foundation, the Keren Kayemet L'Israel (JNF) and the Israel Science Foundation (ISF). Radiocarbon dating research has been supported by the National Science Foundation (NSF), the Exilarch's Foundation and the MPS-WI Center for Integrative Archaeology and Anthropology.

The Mouth Of The Beast

In 1976 several elongated comet-like objects were discovered on pictures taken with the UK Schmidt Telescope in Australia. Because of their appearance, they became known as cometary globules even though they have nothing in common with comets. They were all located in a huge patch of glowing gas called the Gum Nebula. They had dense, dark, dusty heads and long, faint tails, which were generally pointing away from the Vela supernova remnant located at the centre of the Gum Nebula. Although these objects are relatively close by, it took astronomers a long time to find them as they glow very dimly and are therefore hard to detect.

The object shown in this new picture, CG4, which is also sometimes referred to as God's Hand, is one of these cometary globules. It is located about 1300 light-years from Earth in the constellation of Puppis (The Poop, or Stern).

Like the gaping mouth of a gigantic celestial creature, the cometary globule CG4 glows menacingly in this image from ESO's Very Large Telescope. Although it looks huge and bright in this image it is actually a faint nebula and not easy to observe. The exact nature of CG4 remains a mystery.

Credit:  ESO

The head of CG4, which is the part visible on this image and resembles the head of the gigantic beast, has a diameter of 1.5 light-years. The tail of the globule -- which extends downwards and is not visible in the image -- is about eight light-years long. By astronomical standards this makes it a comparatively small cloud.

The relatively small size is a general feature of cometary globules. All of the cometary globules found so far are isolated, relatively small clouds of neutral gas and dust within the Milky Way, which are surrounded by hot ionised material.

The head part of CG4 is a thick cloud of gas and dust, which is only visible because it is illuminated by the light from nearby stars. The radiation emitted by these stars is gradually destroying the head of the globule and eroding away the tiny particles that scatter the starlight. However, the dusty cloud of CG4 still contains enough gas to make several Sun-sized stars and indeed, CG4 is actively forming new stars, perhaps triggered as radiation from the stars powering the Gum Nebula reached CG4.

The cometary globule CG4 glows menacingly, like the gaping mouth of a gigantic celestial creature, in this pan video based on an image from ESO’s Very Large Telescope. What looks huge and bright in this image is actually a faint nebula and not easy to observe. The exact nature of CG4 remains a mystery.

Credit:  ESO. Music: movetwo

Why CG4 and other cometary globules have their distinct form is still a matter of debate among astronomers and two theories have developed. Cometary globules, and therefore also CG4, could originally have been spherical nebulae, which were disrupted and acquired their new, unusual form because of the effects of a nearby supernova explosion. Other astronomers suggest, that cometary globules are shaped by stellar winds and ionising radiation from hot, massive OB star. These effects could first lead to the bizarrely (but appropriately!) named formations known as elephant trunks and then eventually cometary globules.

To find out more, astronomers need to find out the mass, density, temperature, and velocities of the material in the globules. These can be determined by the measurements of molecular spectral lines which are most easily accessible at millimetre wavelengths -- wavelengths at which telescopes like the Atacama Large Millimeter/submillimeter Array (ALMA) operate.

This picture comes from the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO's science archive.


Contact and sources:
Richard Hook
ESO

Long-Necked 'Dragon' Discovered In China



University of Alberta paleontologists including PhD student Tetsuto Miyashita, former MSc student Lida Xing and professor Philip Currie have discovered a new species of a long-necked dinosaur from a skeleton found in China. The findings have been published in a new paper in the Journal of Vertebrate Paleontology.

Qijianglong (pronounced "CHI-jyang-lon") is about 15 metres in length and lived about 160 million years ago in the Late Jurassic. The name means "dragon of Qijiang," for its discovery near Qijiang City, close to Chongqing. The fossil site was found by construction workers in 2006, and the digging eventually hit a series of large neck vertebrae stretched out in the ground. Incredibly, the head of the dinosaur was still attached. "It is rare to find a head and neck of a long-necked dinosaur together because the head is so small and easily detached after the animal dies," explains Miyashita.

This illustration shows what the newly discovered long-necked dinosaur may have looked like.

Credit:  Xing Lida

The new species belongs to a group of dinosaurs called mamenchisaurids, known for their extremely long necks sometimes measuring up to half the length of their bodies. Most sauropods, or long-necked dinosaurs, have necks only about one third the length of their bodies.

Unique among mamenchisaurids, Qijianglong had neck vertebrae that were filled with air, making their necks relatively lightweight despite their enormous size. Interlocking joints between the vertebrae also indicate a surprisingly stiff neck that was much more mobile bending vertically than sideways, similar to a construction crane.

"Qijianglong is a cool animal. If you imagine a big animal that is half-neck, you can see that evolution can do quite extraordinary things." says Miyashita.

This shows the reconstructed skeleton of the newly-discovered dinosaur in the gallery of Qijiang Museum, China.


Mamenchisaurids are only found in Asia, but the discovery of Qijianglong reveals that there could be as many differences among mamenchisaurids as there are between long-necked dinosaurs from different continents.

"Qijianglong shows that long-necked dinosaurs diversified in unique ways in Asia during Jurassic times--something very special was going on in that continent," says Miyashita. "Nowhere else we can find dinosaurs with longer necks than those in China. The new dinosaur tells us that these extreme species thrived in isolation from the rest of the world."

Miyashita believes that mamenchisaurids evolved into many different forms when other long-necked dinosaurs went extinct in Asia. "It is still a mystery why mamenchisaurids did not migrate to other continents," he says. It is possible that the dinosaurs were once isolated as a result of a large barrier such as a sea, and lost in competition with invading species when the land connection was restored later.

The Qijianglong skeleton is now housed in a local museum in Qijiang. "China is home to the ancient myths of dragons," says Miyashita, "I wonder if the ancient Chinese stumbled upon a skeleton of a long-necked dinosaur like Qijianglong and pictured that mythical creature."



Contacts and sources:
Tetsuto Miyashita,
Department of Biological Sciences, University of Alberta

Wednesday, January 28, 2015

New Search Engine Lets Users Look For Relevant Results Faster

Researchers at the Helsinki Institute for Information Technology HIIT have developed a new search engine that outperforms current ones, and helps people to do searches more efficiently.

The SciNet search engine is different because it changes internet searches into recognition tasks, by showing keywords related to the user's search in topic radar. People using SciNet can get relevant and diverse search results faster, especially when they do not know exactly what they are looking for or how to formulate a query to find it.

The SciNet search engine changes Internet searches into recognition tasks, by showing keywords related to the user's search in a topic radar.
Credit:  Aalto University

Once initially queried, SciNet displays a range of keywords and topics in a topic radar. With the help of the directions on the radar, the engine displays how these topics are related to each other. The relevance of each keyword is displayed as its distance from the centre point of the radar - those more closely related are nearer to the centre, and those less relevant are farther away. The search engine also offers alternatives that are connected with the topic, but which the user might not have thought of querying. By moving words around the topic radar, users specify what information is most useful for them.

- According to some estimate the digital universe such as data and documents is expected to grow by 2020 by a factor of 10. Tools that help us transform the time we spend in searching into discovering and understanding information will be increasingly important to enhance productivity and creativity. It is exciting to be addressing this problem in research that needs competencies from different disciplines as we uniquely combine at HIIT, states Professor Giulio Jacucci.

When people are uncertain about a topic, they are typically reluctant to reformulate the original query, even if they need to in order to find the right information. With the help of a keyword cloud, people can more quickly infer which of the search options they receive is more significant for them because they do not need to visit the pages offered by the search engine to find new search words and start again.

-It's often hard for people to put what they are looking for into words. Their search needs often do not become more focused until they begin the actual search. The SciNet search engine solves these problems. It's easier for people to recognise what information they want from the options offered by the SciNet search engine than it is to type it themselves, says the project's coordinator, Tuukka Ruotsalo.

The SciNet search engine and the related user modelling were developed at the Helsinki Institute for Information Technology, HIIT, which is a joint research institute of Aalto University and the University of Helsinki in Finland. On the basis of HIIT's research, the company Etsimo Ltd. was founded to commercialize the search engine, which concentrates on supporting complicated searches.

An article on SciNet and its related modeling solutions, "Interactive Intent Modeling: Information Discovery Beyond Search," was recently published in the prominent computing and information technology journal, Communications of the ACM.


Contacts and sources:
Tuukka Ruotsalo
Aalto University

What Are These Yellowballs In Space?


Some four years ago, a citizen scientist helping the Milky Way Project study Spitzer Space Telescope images for the tell-tale bubble patterns of star formation noticed something else.

"Any ideas what these bright yellow fuzzy objects are?" the volunteer wrote on a project message board.

Well, that sparked some discussion among the professional astronomers on the Milky Way Project and eventually led to a study of the compact objects now known as "yellowballs." A paper just published by the Astrophysical Journal ("The Milky Way Project: What are Yellowballs?") answers some questions about the 900 yellowballs tagged by citizen scientists.

Citizen scientists working with the Milky Way Project noticed and tagged the "yellowballs."

Credit: Image courtesy of NASA/JPL-Caltech.

Charles Kerton, an Iowa State University associate professor of physics and astronomy and a member of the Milky Way Project science team, is first author of the paper. Co-authors are Grace Wolf-Chase of the Adler Planetarium in Chicago and the University of Chicago; Kim Arvidsson, formerly an Iowa State doctoral student and now of Schreiner University in Kerrville, Texas; and Chris Lintott and Robert Simpson of the University of Oxford in the United Kingdom.

"In this paper, through a combination of catalog cross-matching and infrared color analysis, we show that yellowballs are a mix of compact star-forming regions," the astronomers wrote.

And, they wrote, the project demonstrates "the serendipitous nature of citizen science efforts" because Milky Way Project volunteers "went beyond their assigned tasks and started tagging and discussing" the yellowballs.

The Milky Way Project is part of the Zooniverse, a collection of Internet-based science projects that ask for the public's help looking through images and other data.

The Milky Way Project asks people to study tens of thousands of Spitzer's infrared images. People are asked to circle and classify various objects, including bubbles of gas and dust blown by the radiation and charged particles from bright young stars.

To date, citizen scientists have made nearly 1.5 million classifications for the project.

Kerton said all of that classifying is helping astronomers study and map star formation within the galaxy.

But the project took a little detour when citizen scientists noticed yellow objects along the rims of some bubble formations. (It should be noted the yellowballs found in Spitzer's infrared images aren't really yellow. When the images are made, various colors are assigned to represent different wavelengths of infrared light. The yellow color on the images highlights where infrared emission from molecules (colored green) and from hot dust (colored red) completely overlap.)

The astronomers began studying those yellowballs by cross-matching them against existing catalogs of space objects. They also studied the luminosity and physical sizes of 138 of the yellowballs.

Kerton said the researchers found most of the yellowballs were located in regions of the galaxy containing dense gas. They also found that yellowball luminosity was consistent with the luminosity expected for a collection of newly formed massive stars.

They've concluded there's an early "yellowball stage" in the formation of stars 10 to 40 times as massive as our sun. The yellowballs are considered very young versions of the bubble formations.

"All massive stars probably go through this yellowball stage," Kerton said. "The most massive stars go through this stage very early and quickly. Less massive stars go through this stage more slowly."

The astronomers also wrote that further studies of yellowballs will improve our understanding of how regions of massive star formation grow from early compact stages to more evolved and bubble-like structures.

But those findings aren't the only highlight of this particular study, Kerton said.

"The fun thing about this study is the involvement of the citizen scientists," he said. "This is a nice example of people looking at something in the universe and saying, 'That's different,' and then passing it on to professional astronomers."


Contacts and sources:
Charles Kerton
Iowa State University

'Astro-Archaeological' Discovery Of Replica Solar System With Earth-Sized Planets From The Dawn Of Time

Scientists led by University of Birmingham asteroseismologists have discovered a solar system with 5 Earth-sized planets dating back to the dawn of the Galaxy.

Thanks to the NASA Kepler mission, the scientists announced today (Tuesday 27 January 2015) in The Astrophysical Journal the observation of a Sun-like star (Kepler-444) hosting 5 planets with sizes between Mercury and Venus.

Illustration showing Kepler-444, which hosts five Earth-sized planets in very compact orbits. The planets were detected from the dimming that occurs when they transit the disc of their parent star, as shown in this artist's conception.
Credit: Tiago Campante/Peter Devine

Kepler-444 was formed 11.2 billion years ago, when the Universe was less than 20% its current age. This is the oldest known system of terrestrial-sized planets in our Galaxy - two and a half times older than the Earth.

The team carried out the research using asteroseismology - listening to the natural resonances of the host star which are caused by sound trapped within it. These oscillations lead to miniscule changes or pulses in its brightness which allow the researchers to measure its diameter, mass and age. The planets were then detected from the dimming that occurs when the planets transited, or passed across, the stellar disc. This fractional fading in the intensity of the light received from the star enables scientists to accurately measure the size of the planets relative to the size of the star.

This animation starts by showing us Kepler's field-of-view in the direction of the constellations Cygnus and Lyra. We are next taken to the vicinity of the Kepler-444 planetary system, located some 117 light years away. Kepler-444, the parent star, was formed 11.2 billion years ago when the Universe was less than 20% its current age. This pale yellow-orange star is 25% smaller than the Sun and substantially cooler.
Credit: Tiago Campante/Peter Devine.

In the animation we see its five planets transiting in front of the stellar disc. Having sizes between those of Mercury and Venus, they cause a tiny dimming of the light received from the star during transit. The last segment of the animation emphasizes the compactness of this system. The five planets orbit their parent star in less than 10 days or, equivalently, at less than one-tenth Earth's distance from the Sun. In a way, this system may be thought of as a miniature version of the inner planets in our own Solar System. 

Dr Tiago Campante, from the University of Birmingham's School of Physics and Astronomy, who led the research, said: 'There are far-reaching implications for this discovery. We now know that Earth-sized planets have formed throughout most of the Universe's 13.8 billion year history, which could provide scope for the existence of ancient life in the Galaxy.

'By the time the Earth formed, the planets in this system were already older than our planet is today. This discovery may now help to pinpoint the beginning of what we might call the "era of planet formation".'

Professor Bill Chaplin, from the University of Birmingham's School of Physics and Astronomy, who has been leading the team studying solar-type stars using asteroseismology for the Kepler Mission, said: 'The first discoveries of exoplanets around other Sun-like stars in our Galaxy have fuelled efforts to find other worlds like Earth and other terrestrial planets outside our Solar System.

'We are now getting first glimpses of the variety of Galactic environments conducive to the formation of these small worlds. As a result, the path towards a more complete understanding of early planet formation in the Galaxy is now unfolding before us.'


Contacts and sources:
Faye Jackson
University of Birmingham

Stomach Acid-Powered Micromotors Get Their First Test In A Living Animal

Researchers at the University of California, San Diego have shown that a micromotor fueled by stomach acid can take a bubble-powered ride inside a mouse. These tiny motors, each about one-fifth the width of a human hair, may someday offer a safer and more efficient way to deliver drugs or diagnose tumors.

The experiment is the first to show that these micromotors can operate safely in a living animal, said Professors Joseph Wang and Liangfang Zhang of the NanoEngineering Department at the UC San Diego Jacobs School of Engineering.



Wang, Zhang and others have experimented with different designs and fuel systems for micromotors that can travel in water, blood and other body fluids in the lab. "But this is the first example of loading and releasing a cargo in vivo," said Wang. "We thought it was the logical extension of the work we have done, to see if these motors might be able to swim in stomach acid."

Stomach acid reacts with the zinc body of the motors to generate a stream of hydrogen microbubbles that propel the motors forward. In their study published in the journal ACS Nano, the researchers report that the motors lodged themselves firmly in the stomach lining of mice. As the zinc motors are dissolved by the acid, they disappear within a few days leaving no toxic chemical traces.

When they loaded up the motors with a test "payload" of gold nanoparticles, Wang, Zhang and their coworkers found that more of these particles reached the stomach lining when carried by the motors, compared to when the particles alone were swallowed. The motors delivered 168 nanograms of gold per gram of stomach tissue, compared to the 53.6 nanograms per gram that was delivered through the traditional oral route.

This video shows the motion of micromotors in gastric acid.

Credit: Jacobs School of Engineering/UC San Diego

"This initial work verifies that this motor can function in a real animal and is safe to use," said Zhang.

In the experiment, the mice ingested tiny drops of solution containing hundreds of the micromotors. The motors become active as soon as they hit the stomach acid and zoom toward the stomach lining at a speed of 60 micrometers per second. They can self-propel like this for up to 10 minutes.

This propulsive burst improved how well the cone-shaped motors were able to penetrate and stick in the mucous layer covering the stomach wall, explained Zhang. "It's the motor that can punch into this viscous layer and stay there, which is an advantage over more passive delivery systems," he said.

The researchers found that nearly four times as many zinc micromotors found their way into the stomach lining compared with platinum-based micromotors, which don't react with and can't be fueled by stomach acid.

Wang said it may be possible to add navigation capabilities and other functions to the motors, to increase their targeting potential. Now that his team has demonstrated that the motors work in living animals, he noted, similar nanomachines soon may find a variety of applications including drug delivery, diagnostics, nanosurgery and biopsies of hard-to-reach tumors.



Contacts and sources:
Ioana Patringenaru
University of California, San Diego

Mesoamericans Affected By Climate Change, A 600 Year Drought

Scientists have reconstructed the past climate for the region around Cantona, a large fortified city in highland Mexico, and found the population drastically declined in the past, at least in part because of climate change.

Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants at its peak. Scientists believe climate change was part of the reason the city was eventually abandoned.
Credit:  Lawrence Livermore

The research appears in the online edition of the Proceedings of the National Academy of Sciences for the week of Jan. 26.

Lawrence Livermore researcher Susan Zimmerman and colleagues analyzed pollen, stable isotopes and elemental concentrations, which serve as proxies of past climatic and environmental conditions from lake sediments in the region and found evidence of a regional drought between 500 and 1150 AD, about the same time Cantona was abandoned.

Using Lawrence Livermore's Center for Accelerator Mass Spectrometry, the team -- consisting of from the University of California, Berkeley; Universidad Nacional Autonóma de Mexico; and the GFZ German Research Center for Geosciences -- dated terrestrial organic material from 12-meter long sediment cores from the lake to establish the age control for this study. Radiocarbon dating and an age model showed that the centennial-scale arid interval between 500 and 1150 was overlaid on a long-term drying trend. The cores cover the last 6,200 years; however, the team focused on the last 3,800 years.

"We found that Cantona's population grew in the initial phases of the drought, but by 1050 AD long-term environmental stress (the drought) contributed to the city's abandonment," Zimmerman and colleagues said. "Our research highlights the interplay of environmental and political factors in past human responses to climate change."

Cantona was one of the largest cities in pre-Columbian Mesoamerica, with a population of 90,000 inhabitants. It is in a semiarid basin east of Mexico City.

The team conducted a subcentennial reconstruction of regional climate by taking sediment samples from a nearby crater lake, Aljojuca. The modern climate of the region suggests that proxy data from the sediments record changes in summer monsoonal (May through October) precipitation.

"Our results suggest that climate change played a contributing role in the site's history," Zimmerman said.


Contacts and sources:
Anne Stark
Lawrence Livermore National Laboratory 

This Common Drug Increases Dementia Risk Including Alzheimer's Disease

A large study links a significantly increased risk for developing dementia, including Alzheimer's disease, to taking commonly used medications with anticholinergic effects at higher doses or for a longer time. Many older people take these medications, which include nonprescription diphenhydramine (Benadryl). JAMA Internal Medicine published the report, called "Cumulative Use of Strong Anticholinergic Medications and Incident Dementia."


 The study used more rigorous methods, longer follow-up (more than seven years), and better assessment of medication use via pharmacy records (including substantial nonprescription use) to confirm this previously reported link. It is the first study to show a dose response: linking more risk for developing dementia to higher use of anticholinergic medications. And it is also the first to suggest that dementia risk linked to anticholinergic medications may persist--and may not be reversible even years after people stop taking these drugs.

"Older adults should be aware that many medications--including some available without a prescription, such as over-the-counter sleep aids--have strong anticholinergic effects," said Shelly Gray, PharmD, MS, the first author of the report, which tracks nearly 3,500 Group Health seniors participating in the long-running Adult Changes in Thought (ACT), a joint Group Health-University of Washington (UW) study funded by the National Institute on Aging. "And they should tell their health care providers about all their over-the-counter use," she added.

Credit: highriskmedications.weebly.com/

"But of course, no one should stop taking any therapy without consulting their health care provider," said Dr. Gray, who is a professor, the vice chair of curriculum and instruction, and director of the geriatric pharmacy program at the UW School of Pharmacy. "Health care providers should regularly review their older patients' drug regimens--including over-the-counter medications--to look for chances to use fewer anticholinergic medications at lower doses."

For instance, the most commonly used medications in the study were tricyclic antidepressants like doxepin (Sinequan), first-generation antihistamines like chlorpheniramine (Chlor-Trimeton), and antimuscarinics for bladder control like oxybutynin (Ditropan). The study estimated that people taking at least 10 mg/day of doxepin, 4 mg/day of chlorpheniramine., or 5 mg/day of oxybutynin for more than three years would be at greater risk for developing dementia. Dr. Gray said substitutes are available for the first two: a selective serotonin re-uptake inhibitor (SSRI) like citalopram (Celexa) or fluoxitene (Prozac) for depression and a second-generation antihistamine like loratadine (Claritin) for allergies. It's harder to find alternative medications for urinary incontinence, but some behavioral changes can reduce this problem.

"If providers need to prescribe a medication with anticholinergic effects because it is the best therapy for their patient," Dr. Gray said, "they should use the lowest effective dose, monitor the therapy regularly to ensure it's working, and stop the therapy if it's ineffective." Anticholinergic effects happen because some medications block the neurotransmitter called acetylcholine in the brain and body, she explained. That can cause many side effects, including drowsiness, sore throat, retaining urine, and dry mouth and eyes.

"With detailed information on thousands of patients for many years, the ACT study is a living laboratory for exploring risk factors for conditions like dementia," said Dr. Gray's coauthor Eric B. Larson, MD, MPH. "This latest study is a prime example of that work and has important implications for people taking medications--and for those prescribing medications for older patients." Dr. Larson is the ACT principal investigator, vice president for research at Group Health, and executive director of Group Health Research Institute (GHRI). He is also a clinical professor of medicine at the UW School of Medicine and of health services at the UW School of Public Health.

Some ACT participants agree to have their brains autopsied after they die. That will make it possible to follow up this research by examining whether participants who took anticholinergic medications have more Alzheimer's-related pathology in their brains compared to nonusers.


Contacts and sources: 
Rebecca Hughes
University of Washington

Easter Island Mystery

Long before the Europeans arrived on Easter Island in 1722, the native Polynesian culture known as Rapa Nui showed signs of demographic decline. However, the catalyst has long been debated in the scientific community. Was environmental degradation the cause, or could a political revolution or an epidemic of disease be to blame?

A new study by a group of international researchers, including UC Santa Barbara's Oliver Chadwick, offers a different explanation and helps to clarify the chronological framework. The investigators expected to find that changes coincided with the arrival of the Europeans, but their work shows instead that the demise of the Rapa Nui culture began prior to that. Their findings are published in the Proceedings of the National Academy of Sciences.

Monolithic human figures called moai were carved from rock between 1250 and 1500 by the inhabitants of Easter Island, which lies more than 2,000 miles off the coast of Chile.
Credit: UC Santa Barbara

"In the current Easter Island debate, one side says the Rapa Nui decimated their environment and killed themselves off," said Chadwick, a professor in UC Santa Barbara's Department of Geography and the Environmental Studies Program. "The other side says it had nothing to do with cultural behavior, that it was the Europeans who brought disease that killed the Rapa Nui. Our results show that there is some of both going on, but the important point is that we show evidence of some communities being abandoned prior to European contact."

Chadwick joined archaeologists Christopher Stevenson of Virginia Commonwealth University, Cedric Puleston of UC Davis and Thegn Ladefoged of the University of Auckland in examining six agriculture sites used by the island's statue-building inhabitants. Their research focused mainly on the three sites for which they had information on climate, soil chemistry and land use trends as determined by an analysis of obsidian spear points.

The team used flakes of obsidian, a natural glass, as a dating tool. Measuring the amount of water that had penetrated the obsidian's surface allowed them to gauge how long it had been exposed and to determine its age.

The study sites reflected the environmental diversity of the 63-square-mile island situated nearly 2,300 miles off the west coast of Chile. The soil nutrient supply on Easter Island is less than that of the younger Hawaiian Islands, which were also settled by the Polynesians around the same time, 1200 A.D.

All fifteen standing moai at Ahu Tongariki, excavated and restored in the 1990s
Credit: Wikipedia

The first site the researchers analyzed was near the northwest coast. Lying in the rain shadow of a volcano, it had low rainfall and relatively high soil nutrient availability. The second study site, on the interior side of the volcanic mountain, experienced high rainfall but had a low nutrient supply; the third, another near-coastal are in the northeast, was characterized by intermediate amounts of rainfall and relatively high soil nutrients.

"When we evaluate the length of time that the land was used based on the age distribution of each site's obsidian flakes, which we used as an index of human habitation, we find that the very dry area and the very wet area were abandoned before European contact," Chadwick said. "The area that had relatively high nutrients and intermediate rainfall maintained a robust population well after European contact."

These results suggest that the Rapa Nui reacted to regional variations and natural environmental barriers to producing sufficient crops rather than degrading the environment themselves. In the nutrient-rich center where they could produce food well, they were able to maintain a viable culture even under the threat of external factors, including European diseases such as smallpox, syphilis and tuberculosis.

"The pullback from the marginal areas suggests that the Rapa Nui couldn't continue to maintain the food resources necessary to keep the statue builders in business," Chadwick concluded. "So we see the story as one of pushing against constraints and having to pull back rather than one of violent collapse."


Contacts and sources:
Julie Cohen
UC Santa Barbara

Bubbles Half The Size Of The Milky Way

Compared to other galaxies, the Milky Way is a peaceful place. But it hasn't always been so sleepy. In 2010, a team of scientists working at the Harvard-Smithsonian Center for Astrophysics discovered a pair of "Fermi bubbles" extending tens of thousands of light-years above and below the Milky Way's disk. 

From end to end, the newly discovered gamma-ray bubbles (magenta) extend 50,000 light-years, or roughly half of the Milky Way's diameter. 
Credit: NASA's Goddard Space Flight Center

These structures are enormous balloons of radiation emanating from the center of our galaxy. They hint at a powerful event that took place millions of years ago, likely when the black hole at the center of our galaxy feasted on an enormous amount of gas and dust - perhaps several hundreds or even thousands of times the mass of the sun.

Fresh from giving the January 6 Rossi Prize lecture at the Winter American Astronomical Society meeting, three physicists who discovered the Fermi bubbles - Douglas Finkbeiner, Tracy Slatyer and Meng Su - spoke with The Kavli Foundation, revealing that studies of the Fermi bubbles may offer insight into the history of our galaxy. With more study, they could also help in the hunt for dark matter.

"It now seems that, in the past, our black hole was tens of millions of times more active than it is currently," said Meng Su, a Pappalardo Fellow and an Einstein Fellow at the Massachusetts Institute of Technology and the MIT Kavli Institute for Astrophysics and Space Research. "Before the discovery of Fermi bubbles, people were discussing that possibility, but there was no single piece of evidence showing that our black hole could be that active. The Fermi bubble discovery changed the picture."

Hints of the Fermi bubbles' edges were first observed in X-rays (blue) by ROSAT, which operated in the 1990s. The gamma rays mapped by the Fermi Gamma-ray Space Telescope (magenta) extend much farther from the galaxy's plane. 
Credit: NASA's Goddard Space Flight Center

Similar bubbles can be seen in other galaxies, but it's still impossible to say whether the Fermi bubbles were produced by the same mechanism as the others, Meng continued. That's because while the Fermi bubbles shine bright in high-energy gamma rays, bubbles in other galaxies are so far away that their gamma rays cannot be seen from Earth. Instead, the distant bubbles are observed in X-rays, radio and microwaves. Future, more precise measurements of the Fermi bubbles in many wavelengths of light may offer insight into how they compare to bubbles in other galaxies, and could help uncover events that took place in our galaxy's core over the past three to four million years.

But that's not all. Further study of the Fermi bubbles, which the astrophysicists first discovered when looking for dark matter, may in fact help identify dark matter. That's because the center of the galaxy, from whence the bubbles originate, is thought to be one of the best places to find evidence of dark matter. Such evidence could be detected as an excess of gamma rays, produced when dark matter particles interact with one another. To find that excess, astrophysicists will need to thoroughly understand the Fermi bubbles. That understanding will allow the researchers to confidently subtract the gamma rays emitted by the Fermi bubbles from the overall gamma-ray signal before looking for an excess of gamma rays coming from dark matter.

Data from the Fermi Telescope shows the bubbles (in red and yellow) against other sources of gamma rays. The plane of the galaxy (mostly black and white) stretches horizontally across the middle of the image, and the bubbles extend up and down from the center. 
Credit: NASA's Goddard Space Flight Center

In some of the most accepted models of dark matter, "we expect the signals from the galactic center to be significantly brighter than anywhere else in the sky," said Tracy Slatyer, an assistant professor of physics at the Massachusetts Institute of Technology and an Affiliated Faculty member at the MIT Kavli Institute for Astrophysics and Space Research. "So just giving up on the galactic center is not generally a good option."

Indeed, Slatyer continued, there are already hints of dark matter appearing in gamma-ray maps of the galactic center - hints that may eventually lead to the discovery of dark matter.

Douglas Finkbeiner, a professor of astronomy and of physics at Harvard University and a member of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, agreed.

"It would be a supreme irony if we found the Fermi bubbles while looking for dark matter and then while studying the Fermi bubbles we discovered dark matter," he said.


Contacts and sources:
Kavli Institute for Astrophysics and Space Research