RxPG News : Latest Medical, Healthcare and Research News

New device performs better than old for removing blood clots

Fri, 03 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) An experimental blood clot-removing device outperformed the FDA-approved MERCI; retriever device, according to late-breaking science presented at the American Stroke Association's 2012 International Stroke Conference.

The SOLITAIRE; Flow Restoration Device is a self-expanding stent-based design that mechanically removes blood clots from blocked vessels after a stroke. After insertion into the clot using a thin tube, or catheter, the device traps the clot then both device and clot are removed, restoring blood flow. The MERCI retriever uses a tiny corkscrew, guided by a balloon-tipped wire, to snare and remove the blood clot.

In the Solitaire With the Intention for Thrombectomy (SWIFT) trial, the first U.S. clinical trial to compare the two devices, 113 stroke patients at 18 hospitals were randomly assigned to undergo clot removal with either device within eight hours of stroke onset between Feb. 2010-Feb. 2011.

The trial was ended at the suggestion of a safety monitoring committee nearly a year earlier than planned due to significantly better outcomes with the new device. The experimental device opened blocked vessels without causing symptomatic intracranial hemorrhage in 61 percent of patients. The currently approved device had the same result in 24 percent of cases - a statistically significant difference, said Jeffrey L. Saver, M.D., lead author of the study, professor of neurology and director of the Stroke Center in the Geffen School of Medicine at the University of California in Los Angeles.

The use of the new device also led to better survival three months after stroke. There was a 17.2 percent mortality rate with the new device versus 38.2 percent with the older one.

Stroke caused by a blood clot blocking a blood vessel supplying the brain is the most common type of stroke, accounting for about 87 percent of all strokes. The FDA-approved treatment for stroke with the most robust body of evidence is use of a clot-busting drug, but the drug must be given within 4.5 hours of symptom onset, and more quickly in older patients. When clot-busting drugs cannot be used or are ineffective, the clot can sometimes be mechanically removed, during or even after the 4.5 hours. The study didn't compare mechanical clot removal to drug treatment.

Although not yet approved in the United States, the new device is approved in Europe.

Other specific findings - all of which were statistically significant - were:

Two percent of SOLITAIRE-treated patients had symptoms of bleeding in the brain compared to 11 percent of MERCI patients.

At the 90-day follow-up, overall adverse event rates, including bleeding in the brain, were similar for the two devices.

Fifty-eight percent of SOLITAIRE-treated patients had good mental/motor functioning at 90 days compared to 33 percent of MERCI patients.

The SOLITAIRE device also opened more vessels when used as the first treatment approach, necessitating fewer subsequent attempts with other devices or drugs.

Patients' average age was 67 years and 68 percent were male. Forty percent had not improved with standard clot-busting medication prior to the study, while the remainder had not received it.

The time from the start of symptoms to start of the clot retriever treatment was on average 4.9 hours for SOLITAIRE and 5.3 hours for MERCI. The study results account for this time difference.

This heralds a new era in acute stroke care, said Saver. We're going from our first generation of recanalization procedures, which were only moderately good in reopening target arteries, to now having a highly effective recanalization device. This really is a game-changing result.

Gene related to fat preferences in humans found

Fri, 03 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) A preference for fatty foods has a genetic basis, according to researchers, who discovered that people with certain forms of the CD36 gene may like high-fat foods more than those who have other forms of this gene.

The results help explain why some people struggle when placed on a low-fat diet and may one day assist people in selecting diets that are easier for them to follow. The results also may help food developers create new low-fat foods that taste better.

Fat is universally palatable to humans, said Kathleen Keller, assistant professor of nutritional sciences, Penn State. Yet we have demonstrated for the first time that people who have particular forms of the CD36 gene tend to like higher fat foods more and may be at greater risk for obesity compared to those who do not have this form of the gene. In animals, CD36 is a necessary gene for the ability to both detect and develop preferences for fat. Our study is one of the first to show this relationship in humans.

Keller and a tem of scientists from Penn State, Columbia University, Cornell University and Rutgers University examined 317 African-American males and females because individuals in this ethnic group are highly vulnerable to obesity and thus are at greatest risk for obesity-related diseases.

The team gave the participants Italian salad dressings prepared with varying amounts of canola oil, which is rich in long-chain fatty acids. The participants were then asked to rate their perceptions of the dressings' oiliness, fat content and creaminess on a scale anchored on the ends with extremely low and extremely high.

The team also gave participants questionnaires aimed at understanding their food preferences. Participants rated how much they liked each food on a scale anchored with dislike extremely and like extremely. Foods included on the questionnaire were associated with poor dietary intake and health outcomes, such as half-and-half, sour cream, mayonnaise, bacon, fried chicken, hot dogs, French fries, cheese, chips, cake, cookies and doughnuts. The researchers collected saliva samples from the participants to determine which forms of CD36 they had. From the saliva samples, they extracted DNA fragments and examined differences in the CD36 gene contained within the fragments.

They found that participants who had the AA form of the gene -- present in 21 percent of the population -- rated the salad dressings as creamier than individuals who had other forms of the gene. These individuals reported that the salad dressings were creamier regardless of how much fat was actually in them. The researchers also found that AA individuals liked salad dressings, half-and-half, olive oil and other cooking oils more than those who had other forms of the gene. The results are published in a recent issue of the journal

Cardiovascular Nursing Spring Meeting

Thu, 02 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) New scientific findings and hot topics in cardiovascular nursing will be the focus of the 12th Annual Spring Meeting on Cardiovascular Nursing. Managing in today's challenging financial environment and dealing with the increasing issue of cardiovascular disease in dementia patients are just two items on the packed agenda.

Some 200 abstracts will be presented by nurses and allied professionals on a wide range of topics including arrhythmias, heart failure, prevention, acute care, myocardial infarction and implantable devices. There's such a breadth of research and quality improvement projects that nurses and AHPs (allied health professionals) bring to this congress, says Professor Christi Deaton, immediate past-chairperson of the Council on Cardiovascular Nursing and Allied Professions (CCNAP).

This year's meeting, 'Health at Heart', is organised jointly by the (CCNAP) of the European Society of Cardiology (ESC) and the Professional Society for Cardiovascular and Thorax Surgery Nurses, based in Denmark. It will be held 16-17 March 2012 at the state of the art Bella Centre in Copenhagen, Denmark.

New scientific findings will be presented on risky behaviours in adolescents with congenital heart disease, the links between depression and heart disease, the impact of art on quality of life in stroke survivors, and numerous other subjects of interest to journalists and the wider public.

This year will see a record number of moderated posters presented, a great opportunity for journalists to get stories and speak to the researchers. We increased the number of moderated poster sessions because it was such a popular forum last year, says Dr Kaat Siebens, chairperson of the CCNAP. It was an excellent opportunity to see the posters up close and have a good discussion with the scientists.

In addition to the abstracts, sessions will be held on hot topics in cardiovascular nursing that affect large numbers of patients. A session on fear in cardiovascular patients will consider whether fear is a positive coping strategy or negative emotional status, how fear can lead to delays in seeking treatment, and the relationship between fear and inflammation, which is associated with worse outcomes. Another session will explore the growing problem of how to manage complex cardiovascular problems in older patients with dementia.

A session will be devoted to leadership and management in difficult times, including how to get nurse-patient ratios right and how to motivate and retain experienced nurses. This is particularly newsworthy given today's financial climate. We are in difficult financial times and that affects healthcare, says Professor Deaton. Oftentimes healthcare systems decrease staffing when there is an economic crisis.

For the first time a daily congress news will be distributed which highlights events not to be missed by delegates and the press, and the day's top three abstracts (oral, moderated poster, and poster), chosen by the CCNAP and dubbed the 'Reviewers Choice'.

Also new will be on-site interviews with key figures, including a nurse prescriber who can discuss this important subject ahead of the 2013 meeting in Glasgow, where nurses can prescribe.

The meeting attracts around 600 nurses, allied professionals and technicians from Europe and beyond. Delegates and journalists will stay at the striking Bella Sky Comwell Hotel, which is attached to the congress centre. For those who wish to visit the city centre, Copenhagen Central Station is just 10-15 minutes' drive away.

We drafted the scientific programme with topics that are really important for our delegates, concludes Dr Siebens. And everybody is feeling the crisis, so I think one of the most important sessions will be the one regarding leadership and management in difficult times.

The effect of occasional binge drinking on heart disease and mortality among moderate drinkers

Thu, 02 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) Most studies have found that binge drinking is associated with a loss of alcohol's protective effect against ischemic heart disease (IHD) and most studies have found an increase of coronary risk among binge drinkers.

This study followed 26,786 men and women who participated in the Danish National Cohort Study in 1994, 2000, and 2005 and sought to see if binge drinking increased the risk of IHD or all-cause mortality among light-to-moderate drinkers: (up to 21 drinks/week for men and up to 14 drinks/week for women). A drink was 12g.

Binge drinking (more that 5 drinks on an occasion) did not show differences in risk of ischemic heart disease (coronary disease) or total mortality than among always moderate drinkers. These results are somewhat different from results of many other epidemiologic studies that have shown increased risk of health problems (even higher risk of coronary disease) to be associated with what was referred to as binge drinking.

Why there were no adverse effects of binge drinking in this study has provoked considerable discussion among members of the Forum. The assessments of alcohol were based on consumption in the week prior to the examination, so data was not available to judge whether or not binge-drinking episodes occurred rarely or regularly. Data was available for smoking, education, physical activity, BMI, and self-reported hypertension and diabetes. There was a strong increase in IHD risk and mortality from binge drinking among heavy drinkers, but the authors were comparing outcomes in binge vs. non-binge drinkers among subjects in the light-to-moderate categories, and so in all comparisons, the relative risk of IHD and all-cause mortality was higher for non-drinkers than for all other categories of drinkers.

The general consensus of opinion among Forum members is the definition of binge drinking. The rapid consumption of more than 5 drinks on an empty stomach surely has different effects than the consumption of alcohol over several hours with food, such as during a prolonged dinner. The rate of consumption strongly affects the consequences of alcohol; the speed of drinking and context should constitute part of the definition of 'bingeing' and not just the total number of drinks.

The Forum concludes that binge drinking, however defined, is not a healthy pattern of alcohol consumption. But the circumstances of consumption (rate of consumption, with or without food, etc.) may also be important in its definition and in judging its effects on health.

The Forum does not take the results of this single study to support binge drinking. What the Danish results suggest is that the occasional excess embedded in a moderate consumption pattern is not shown to be harmful in this study. As recognized in responsible drinking guidelines from Australia, Canada and the US, occasional episodes of consumption greater than the recommended daily levels do not necessarily change the classification of a normally moderate drinker into that of an abuser.

ORNL, partners earn FLC honor for cookstove technology

Thu, 02 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) Envirofit International, the Department of Energy's Oak Ridge National Laboratory and Colorado State University have won a Federal Laboratory Consortium award for excellence in technology transfer for a clean-burning cookstove designed for the developing world.

The story began in 2007 when Envirofit and Colorado State approached ORNL in search of guidance for selecting a commercially available low-cost metal combustor alloy able to withstand harsh operating conditions. The combustor component in the Envirofit stove design had to resist temperatures up to 1,650 degrees Fahrenheit in the presence of corrosive compounds resulting from burning a variety of biomass. The metal cost could not exceed a few dollars per pound.

Mike Brady of ORNL's Materials Science and Technology Division led a team that identified a family of low-cost iron-based alloys with the potential to meet Envirofit's design targets. ORNL also assisted Envirofit in specifying alloy compositional tolerances needed to achieve durability targets without significantly increasing alloy cost.

Under a work for others agreement funded by Envirofit, ORNL provided ongoing alloy specification and impurity tolerance input, assisted with the design and interpretation of corrosion studies to assess the durability of candidate alloys. ORNL also performed advanced characterization of corrosion products on laboratory and field-tested metal components.

This knowledge transfer resulted in a joint patent disclosure between Envirofit and Colorado State University, and ORNL for the metal combustor component and cookstove assembly.

To date, more than 150,000 Envirofit G-3300 stoves have been sold in the developing world. These stoves reduce smoke and harmful gases by up to 80 percent, reduce fuel use by up to 60 percent and reduce cooking time by up to 50 percent compared to traditional cooking fires and stoves. The core technology developed for the G-3300 has now been integrated across six models of wood and charcoal stoves.

Brady noted that this success story illustrates technology transfer at its best as ORNL was able to quickly provide materials selection guidance by leveraging extensive experience in high-temperature materials. This expertise was gained under the Department of Energy's Energy Efficiency and Renewable Energy Industrial Technologies programs and Fossil Energy Advanced Research Materials programs.

Other ORNL members of the team were Larry Walker, David Stinton, Tim Theiss, Thomas Rosseel, Joe Marasco, Alex DeTrana and Frank Damiano. The award citation was for Materials for a Low-Cost, Clean Cookstove.

DOE laboratories won a total of seven of the 23 FLC awards for 2012 with the other honors going to Argonne National Laboratory, Los Alamos National Laboratory, National Energy Technology Laboratory, Pacific Northwest National Laboratory and Sandia National Laboratories. The awards will be presented May 3 at the FLC national meeting in Pittsburgh.

Clot-busting drugs appear safe for treating 'wake-up' stroke patients

Wed, 01 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) Clot-busting drugs may be safe for patients who wake up experiencing stroke symptoms, according to preliminary research presented at the American Stroke Association's International Stroke Conference 2012.

In wake-up stroke, the person wakes up with symptoms after going to sleep with none. Not knowing when the stroke began excludes these patients from anti-clotting drugs that must be given within 4.5 hours of the beginning of the stroke.

Because wake-up strokes are common, occurring in up to a quarter of stroke sufferers, more research is needed on how to treat these patients, said Dulka Manawadu, M.D., lead researcher and a stroke medical consultant at King's College Hospital in London, U.K. Patients who experience stroke symptoms should call Emergency Medical Services urgently and get to the hospital fast, regardless of the time of onset. This will help specialists decide if novel interventions are appropriate and feasible.

In the study, researchers used a stroke registry to compare clot busting treatments received by 326 patients within 4.5 hours of symptom onset to 68 wake-up stroke patients, with unknown onset.

All the patients were treated in the same London medical center, where 20 percent suffered wake-up stroke. Researchers didn't randomly assign patients to receive different treatments for comparison, which is the gold standard and, thus, a limitation of the study.

Our study shows that administering clot-busting drugs to patients with wake-up stroke who have the same clinical and imaging features as those treated within current guidelines is feasible and safe, Manawadu said.

Researchers analyzed information on patients who received the clot-buster alteplase, sold under the name Activase, between January 2009 and December 2010. Wake-up stroke patients received clot-busting treatments if their clinical presentation and early stroke changes on CT scan images were comparable to those treated with a known time of onset. Both groups had similar blood pressure, blood sugar levels and scores on the National Institutes of Health Stroke Scale, which is a standardized method used by healthcare professionals to measure the level of impairment caused by a stroke.

After three months, the researchers found the wake-up stroke patients' death rates, risk of bleeding inside the brain, and the proportion that made a good recovery were similar to those patients treated within a known 4.5 hours of stroke onset.

Sometimes, doctors are reluctant to give clot-busting drugs to patients in whom the time of stroke onset is not known, because the risks of bleeding are not known, Manawadu said. However, a significant proportion of patients who have stroke symptoms on waking may have suffered stroke in the early hours of the morning and may still be within the window of time where clot-busting treatments are known to be effective. It is also likely that advanced imaging techniques may help to identify patients with wake-up stroke who have the potential to benefit from clot-busting drugs.

This is an area of growing importance because it may allow us to extend the indication for this effective treatment, Manawadu said. Research has been limited to date but the time is ripe to investigate effective treatments in this group of patients.

Infections in childhood linked to high risk of ischemic stroke

Wed, 01 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) Common infections in children pose a high risk of ischemic stroke, according to research presented at the American Stroke Association's International Stroke Conference 2012.

In a review of 2.5 million children, the researchers identified 126 childhood ischemic stroke cases and then randomly selected 378 age-matched controls from the remaining children without stroke. They discovered that 29 percent of those who suffered a stroke had a medical encounter for infection in the two days preceding the stroke versus one percent of controls during the same dates.

In the three- to seven-day window, 13 percent of children had an infection compared to 2 percent of controls.

The elevated risk of stroke didn't persist after the first month of infection, researchers said.

This is the first large study to establish the relationship between infection and stroke in children, said Heather Fullerton, M.D., the study's principal investigator and director of the Pediatric Stroke and Cerebrovascular Disease Center at the University of California in San Francisco.

Researchers analyzed diagnostic and radiologic databases of children enrolled in the Kaiser Permanente healthcare plan from 1993 to 2007. They evaluated medical records and chart reviews for infections during the two years prior to the childhood stroke, and the same time period for the age-matched controls.

The children with stroke ranged from infants to adolescents, average 10.5 years old (oldest child was 19). Researchers identified three stroke-free controls per case. Findings between girls and boys or ethnic groups didn't differ.

Researchers found acute infections are more important in triggering stroke than chronic infections over time.

These were predominantly minor acute infections and represented a variety of infections, including upper respiratory infections, urinary tract infections and ear infections, Fullerton said. No particular type of infection predominated.

The study findings hold implications for the secondary prevention of stroke in children, she said.

Most previously healthy children with an ischemic stroke have a disease of the blood vessels to the brain, and these children are at highest risk of recurrent stroke. This study may provide some insight into why children develop this arteriopathy: the inflammatory process that results from an infection which may lead to stroke by causing vascular injury, researchers said.

The standard treatment for ischemic stroke in children is blood thinners. But the study suggests that future research should focus on the potential role for anti-inflammatory medications in preventing the recurrence of stroke in this population.

The incidence of stroke in childhood is about five per 100,000 in the United States each year, Fullerton said.

About half of childhood strokes are hemorrhagic (bleeding in the brain), according to American Heart Association statistics.

Childhood infections are exceedingly common, while childhood strokes are uncommon, Fullerton said. Parents should not be alarmed at the findings of this study. We suspect that there are rare genetic factors that may place some children at risk for this uncommon effect of common infections.

Infection is an established risk factor for ischemic stroke in adults. In the United States, stroke is the fourth leading cause of death and a leading cause of serious disability among adults.

Penn State scientists elected to American Geophysical Union

Wed, 01 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) Michael Mann and David Pollard, both scientists in Penn State's College of Earth and Mineral Sciences, have been elected as Fellows of the American Geophysical Union for exceptional contributions in original research in climate change.

Election as an AGU Fellow is one of the highest honors for scientists in Earth and space sciences. No more than 0.1 percent of AGU's 60,000-plus members is elected annually as Fellows. Only 61 scientists will receive the honor this year.

Mann, professor of meteorology and geosciences and director of the University's Earth System Science Center, is best known for using theoretical climate-system models and analyzing observational climate records to advance understanding of the Earth's climate and the changes -- both those naturally occurring and human-forced -- that have occurred over time.

In the late 1990s, Mann with colleagues published the hockey stick graph of Northern Hemisphere temperatures over the past millennium. Based upon so-called proxy climate records such as ice cores, tree rings and corals, the graph demonstrates significant global warming in the last century. The graph, which has become a lightning rod for climate-change deniers, and the ensuing controversy are the subject of Mann's soon-to-be-released book, The Hockey Stick and the Climate Wars: Dispatches From the Front Lines.

Mann was lead author of the Intergovernmental Panel on Climate Change Third Scientific Assessment Report and was among the scientists who shared the 2007 Nobel Peace Prize with Al Gore for that report. More recently, he was awarded the Hans Oeschger Medal of the European Geosciences Union in recognition of his climate-related work.

The author of more than 140 peer-reviewed and edited publications, Mann is co-author with Penn State Geoscientist Lee Kump of Dire Predictions, Understanding Global Warming: The Illustrated Guide to the Findings of the IPCC.

Mann received his undergraduate degrees in physics and applied math from the University of California at Berkeley, a master's degree in physics and a doctorate in geology and geophysics from Yale University. He joined Penn State in 2005.

Pollard, senior scientist, Earth and Environmental Systems Institute, works with global climate models and ice-sheet models to both investigate the physical processes that have shaped Earth's climate over geologic time and project the future of the Earth's system. By coupling and applying these models in innovative ways, Pollard has developed several new modeling techniques.

One of these has allowed floating ice shelves to be integrated efficiently and realistically into ice-sheet models. With these, Pollard has been able to create simulations of the advance and retreat of the grounding line -- where floating ice shelves and grounded ice meet -- of the fragile and vulnerable West Antarctic ice sheet, much of which rests on bedrock far below sea level. Melting of the great polar ice sheets will result in global sea-level rise.

Using this model, Pollard and Robert DeConto, a colleague at the University of Massachusetts, have simulated the past 5 million years of West Antarctic ice sheet variations. The results indicate the West Antarctic ice sheet has collapsed and re-grown multiple times, a conclusion confirmed by data from sediment cores drilled by the AntarcticGeological Drilling project.

The model also extends the reach of the core data to a wider geographical context and not just the spot drilled.

Pollard is currently applying the model to the future to assess the danger of West Antarctic ice sheet collapse in the next few centuries or millennium due to anthropogenic climate warming.

As an associate scientist at the National Center for Atmospheric Research in the early 1990s, Pollard was one of the main developers of the Genesis Global Climate Model, which has been widely used for studies of paleoclimate.

Pollard's research has been reported in more than 130 authored or co-authored publications in peer-reviewed literature.

Pollard, who came to Penn State in 1997, received his undergraduate degree in mathematics from Cambridge University, a master's degree in aeronautics and a doctorate in planetary science from California Institute of Technology.

Mann and Pollard will be recognized during an Honors Ceremony at the 2012 AGU Fall Meeting held Dec. 6-10, in San Francisco.

Wayne State University project aims to reduce HIV, AIDS among African-Americans

Wed, 01 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) DETROIT -- A grant from the Centers for Disease Control and Prevention, administered by the Michigan Department of Community Health, is helping a Wayne State University researcher's effort to promote HIV testing among African-Americans.

Dana Rice, Dr.P.H., adjunct assistant professor of family medicine and public health sciences, has received $166,000 to expand HIV testing in the Wayne County jails to reduce racial and ethnic health disparities.

We have a huge disparity in racial and ethnic HIV rates in the United States, she said, noting that black men and women make up only 14 percent of the general population in Michigan, but 58 percent of people living with HIV or AIDS. Officials said that from January through December 2011, 72 percent of all inmates in Wayne County jails were African-American.

This project helps to at least tackle the primary issue of HIV prevention, which is that most people don't know their status, said Rice, a resident of Southfield. We are helping to support making individuals more knowledgeable about their HIV status by providing this service in a place where there is a high-risk population.

Her team is conducting HIV screening in county jails in collaboration with community partners. It also provides comprehensive HIV prevention services to inmates, including counseling and referrals to care for those who test positive.

That counseling helps inmates understand and reduce risk factors, and implement risk-reduction strategies to prevent them from acquiring or spreading the disease.

Researchers also inform them about the basics of HIV and how it affects the body.The grant helps continue a program that began in 2008, when Rice was director of the Health Promotion and Disease Prevention Department for the Wayne County Jail Health Services Division. The first portion of the funding expires March 31, but she expects it to be extended by an additional $166,000 to last through Sept. 30.

Rice said it is important to increase HIV testing among African-Americans because of the lack of knowledge and information within the community, where she said there has been complacency because HIV- and AIDS-related deaths aren't as prevalent as in the early 1980s, when the condition first became widely known.

Many high-risk people don't get tested because of the social stigma associated with HIV, which still is transmitted by high-risk behaviors and compounded by other socioeconomic issues within the community, Rice said.

Research assistants will work in county jail facilities to provide rapid testing results (within 20 minutes) to all inmates on an opt-out basis. Everyone is offered the test and specifically must decline it in writing.

Providing the test as a standard service helps reduce some of the stigma associated with the test and the disease, Rice said, while encouraging and promoting healthy behaviors that researchers hope will continue when the inmates are released.

It's not the social norm in our society that one should know their HIV status like their blood pressure or their blood type, she said. We really have to change the norms in our communities and reduce the stigma to recognize that knowing one's HIV status is vital personal health information.

It's also critical to public health, as we need to get people who have HIV diagnosed and linked into care to effectively reduce its transmission in the community.

Scientists help define structure of exoplanets

Wed, 01 Feb 2012 05:00:00 PST

( From http://www.rxpgnews.com ) LIVERMORE, Calif. -- Using models similar to those used in weapons research, scientists may soon know more about exoplanets, those objects beyond the realm of our solar system.

In a new study, Lawrence Livermore National Laboratory scientists and collaborators came up with new methods for deriving and testing the equation of state (EOS) of matter in exoplanets and figured out the mass-radius and mass-pressure relations for materials relevant to planetary interiors.

Astronomers started detecting exoplanets 18 years ago and more than 700 have been found so far, the vast majority within the last two years. Interest is now growing in the structure and atmospheres of these worlds.

New equation-of-state work helps interpret the structure of exoplanets. As there is a minimal amount of data in each exoplanet observation, interpretation of their composition and structure depends largely on comparing their mass and radius with the composition expected given the distance from their parent star. The makeup implies a mass-radius relation, which relies heavily on EOS calculated from electronic structure theory and measured experimentally on Earth.

In the new research, lead Laboratory scientist Damian Swift, along with LLNL colleagues Jon Eggert, Damien Hicks, Sebastien Hamel, Kyle Caspersen, Eric Schwegler and Rip Collins, compared their modeling results with the observed masses and radii of exoplanets. Their results broadly support recent assumptions about the structures of exoplanets but can now take advantage of the accurate EOS models and data produced at Livermore.

Current theoretical techniques for calculating electronic structures can predict EOS relevant to planetary interiors, Swift said. But we still need experimental validation of these calculations; something that can now be done at the National Ignition Facility (NIF).

LLNL's National Ignition Facility is the world's largest laser designed to perform research on national security, fusion experimentation and basic science, such as astrophysics.

The team made specific predictions for notable exoplanets having earth-like, rocky, icy compositions, with planetary center pressures ranging from 8 to 19,000 Mbar (8 million to 1.9 billion atmospheres of pressure).

We have a project to measure material properties up to billions of atmospheres on NIF. We will eventually exceed the highest pressures investigated in the very small number of previous experiments using underground nuclear tests, which reached far above pressures that can be explored with other techniques currently available, Swift said.

Placing constraints on the structure of exoplanets requires accurate information about the compressibility of relevant compositions of matter, including iron alloys, silicates, and ices, under extreme conditions of pressure and temperature.

This sets the record straight and presents a survey of exoplanet structure information using material properties generated for, and validated using, experimental capabilities at the national labs, Swift said.