NASA's Swift finds a gamma-ray burst with a dual personality

ScienceDaily (Nov. 30, 2011) — A peculiar cosmic explosion first detected by NASA's Swift observatory on Christmas Day 2010 was caused either by a novel type of supernova located billions of light-years away or an unusual collision much closer to home, within our own galaxy. Papers describing both interpretations appear in the Dec. 1 issue of the journal Nature.

Gamma-ray bursts (GRBs) are the universe's most luminous explosions, emitting more energy in a few seconds than our sun will during its entire energy-producing lifetime. What astronomers are calling the "Christmas burst" is so unusual that it can be modeled in such radically different ways.

"What the Christmas burst seems to be telling us is that the family of gamma-ray bursts is more diverse than we fully appreciate," said Christina Thoene, the supernova study's lead author, at the Institute of Astrophysics of Andalusia in Granada, Spain. It's only by rapidly detecting hundreds of them, as Swift is doing, that we can catch some of the more eccentric siblings."

Common to both scenarios is the presence of a neutron star, the crushed core that forms when a star many times the sun's mass explodes. When the star's fuel is exhausted, it collapses under its own weight, compressing its core so much that about a half-million times Earth's mass is squeezed into a sphere no larger than a city.

The Christmas burst, also known as GRB 101225A, was discovered in the constellation Andromeda by Swift's Burst Alert Telescope at 1:38 p.m. EST on Dec. 25, 2010. The gamma-ray emission lasted at least 28 minutes, which is unusually long. Follow-up observations of the burst's afterglow by the Hubble Space Telescope and ground-based observatories were unable to determine the object's distance.

Thoene's team proposes that the burst occurred in an exotic binary system where a neutron star orbited a normal star that had just entered its red giant phase, enormously expanding its outer atmosphere. This expansion engulfed the neutron star, resulting in both the ejection of the giant's atmosphere and rapid tightening of the neutron star's orbit.

Once the two stars became wrapped in a common envelope of gas, the neutron star may have merged with the giant's core after just five orbits, or about 18 months. The end result of the merger was the birth of a black hole and the production of oppositely directed jets of particles moving at nearly the speed of light, followed by a weak supernova.

The particle jets produced gamma rays. Jet interactions with gas ejected before the merger explain many of the burst's signature oddities. Based on this interpretation, the event took place about 5.5 billion light-years away, and the team has detected what may be a faint galaxy at the right location.

"Deep exposures using Hubble may settle the nature of this object," said Sergio Campana, who led the collision study at Brera Observatory in Merate, Italy.

If it is indeed a galaxy, that would be evidence for the binary model. On the other hand, if NASA's Chandra X-ray Observatory finds an X-ray point source or if radio telescopes detect a pulsar, that goes against it.

Campana's team supports an alternative model that involves the tidal disruption of a large comet-like object and the ensuing crash of debris onto a neutron star located only about 10,000 light-years away. The scenario requires the break-up of an object with about half the mass of the dwarf planet Ceres. While rare in the asteroid belt, such objects are thought to be common in the icy Kuiper belt beyond Neptune. Similar objects located far away from the neutron star may have survived the supernova that formed it.

Gamma-ray emission occurred when debris fell onto the neutron star. Clumps of cometary material likely made a few orbits, with different clumps following different paths before settling into a disk around the neutron star. X-ray variations detected by Swift's X-Ray Telescope that lasted several hours may have resulted from late-arriving clumps that struck the neutron star as the disk formed.

In the early years of studying GRBs, astronomers had very few events to study in detail and dozens of theories to explain them. In the Swift era, astronomers have settled into two basic scenarios, either the collapse of a massive star or the merger of a compact binary system.

"The beauty of the Christmas burst is that we must invoke two exotic scenarios to explain it, but such rare oddballs will help us advance the field," said Chryssa Kouveliotou, a co-author of the supernova study at NASA's Marshall Space Flight Center in Huntsville, Ala.

NASA's Swift was launched in November 2004 and is managed by Goddard. It is operated in collaboration with several U.S. institutions and partners in the United Kingdom, Italy, Germany and Japan.

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The above story is reprinted from materials provided by NASA/Goddard Space Flight Center.

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Journal References:

C. C. Thöne, A. de Ugarte Postigo, C. L. Fryer, K. L. Page, J. Gorosabel, M. A. Aloy, D. A. Perley, C. Kouveliotou, H. T. Janka, P. Mimica, J. L. Racusin, H. Krimm, J. Cummings, S. R. Oates, S. T. Holland, M. H. Siegel, M. De Pasquale, E. Sonbas, M. Im, W.-K. Park, D. A. Kann, S. Guziy, L. Hernández García, A. Llorente, K. Bundy, C. Choi, H. Jeong, H. Korhonen, P. Kubànek, J. Lim, A. Moskvitin, T. Muñoz-Darias, S. Pak, I. Parrish. The unusual ?-ray burst GRB 101225A from a helium star/neutron star merger at redshift 0.33. Nature, 2011; 480 (7375): 72 DOI: 10.1038/nature10611S. Campana, G. Lodato, P. D’Avanzo, N. Panagia, E. M. Rossi, M. Della Valle, G. Tagliaferri, L. A. Antonelli, S. Covino, G. Ghirlanda, G. Ghisellini, A. Melandri, E. Pian, R. Salvaterra, G. Cusumano, V. D’Elia, D. Fugazza, E. Palazzi, B. Sbarufatti, S. D.Vergani. The unusual gamma-ray burst GRB 101225A explained as a minor body falling onto a neutron star. Nature, 2011; 480 (7375): 69 DOI: 10.1038/nature10592

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Watermelon reduces atherosclerosis, animal study finds

ScienceDaily (Oct. 27, 2011) — In a recent study by University of Kentucky researchers, watermelon was shown to reduce atherosclerosis in animals.

The animal model used for the study involved mice with diet-induced high cholesterol. A control group was given water to drink, while the experimental group was given watermelon juice. By week eight of the study, the animals given watermelon juice had lower body weight than the control group, due to decrease of fat mass. They experienced no decrease in lean mass. Plasma cholesterol concentrations were significantly lower in the experimental group, with modestly reduced intermediate and low-density lipoprotein cholesterol concentrations as compared to the control group.

A measurement of atherosclerotic lesion areas revealed that the watermelon juice group also experienced statistically significant reductions in atherosclerotic lesions, as compared to the control group.

"Melons have many health benefits," said lead investigator Dr. Sibu Saha. "This pilot study has found three interesting health benefits in mouse model of atherosclerosis. Our ultimate goal is to identify bioactive compounds that would improve human health."

The study was conducted by Sibu Saha, UK Department of Surgery; Aruna Poduri, UK Saha Cardiovascular Research Center (UK Saha CRVC); Debra L. Rateri, UK Saha CVRC; Shubin Saha of Purdue Univ.; and Alan Daugherty, director, UK Saha CVRC.

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Lower dose of corticosteroids just as effective as higher for shoulder pain, study finds

ScienceDaily (Oct. 27, 2011) — Although corticosteroid injections are one of the most common treatments for shoulder pain, there have been relatively few high-quality investigations of their efficacy and duration of action. In a study scheduled for publication in the December issue of the Archives of Physical Medicine and Rehabilitation, researchers report on the first comparative study of the two most commonly corticosteroid doses administered for shoulder pain. They found that lower doses were just as effective as higher doses in terms of reduction of pain, improved range of motion and duration of efficacy.

"There has been no guidance for adequate corticosteroid doses during subacromial injection. Physicians have depended mainly on their experience for the selection of dose," commented lead investigator Seung-Hyun Yoon, MD, PhD, Assistant Professor, Department of Physical Medicine and Rehabilitation, Ajou University School of Medicine, Suwon, Republic of Korea. "This is the first study to assess the efficacy of corticosteroid according to two different doses, which are the most widely used in subacromial injection for participants with periarticular shoulder disorders. Initial use of a low dose is encouraged because there was no difference in efficacy according to dose, and the effect of corticosteroid lasted up to 8 weeks."

Investigators conducted a randomized, triple-blind, placebo-controlled clinical trial in which 79 patients with at least one month's duration of pain were enrolled. Subjects were randomly assigned to three groups with 27 participants receiving a 40 mg dose of triamcinolone acetonide; 25 a 20 mg dose and 27 a placebo injection. All were followed up at 2, 4, and 8 weeks after treatment. All injections were performed using ultrasound guidance to insure proper placement of the therapeutic agent in the bursa.

Participants were asked to rate their degree of shoulder pain on a 0 to 10 scale and to answer a Shoulder Disability Questionnaire. They also were asked to move their shoulders slowly until they experienced pain, and evaluators measured the Active Range of Motion (AROM) in 4 different directions (forward flexion, abduction, internal rotation, and external rotation of the shoulder in a standing position).

Compared with pretreatment (within-group comparisons), the high- (40 mg) and low-dose corticosteroid (20 mg) groups both showed improvement in pain, disability, and AROM, while the placebo group showed no difference. Importantly, this study showed no significant inter-group differences between the high- and low-dose corticosteroid groups. Because a higher dose may increase the incidence of local and general complications, a lower dose is indicated at the initial treatment stage.

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Ji Yeon Hong, Seung-Hyun Yoon, Do Jun Moon, Kyu-Sung Kwack, Bohyun Joen, Hyun Young Lee. Comparison of High- and Low-Dose Corticosteroid in Subacromial Injection for Periarticular Shoulder Disorder: A Randomized, Triple-Blind, Placebo-Controlled Trial. Archives of Physical Medicine and Rehabilitation, December 2011; DOI: 10.1016/j.apmr.2011.06.033

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Regular aspirin intake halves cancer risk, study finds

ScienceDaily (Oct. 28, 2011) — Scientists including those from Queen's University have discovered that taking regular aspirin halves the risk of developing hereditary cancers.

Hereditary cancers are those which develop as a result of a gene fault inherited from a parent. Bowel and womb cancers are the most common forms of hereditary cancers. Fifty thousand people in the UK are diagnosed with bowel and womb cancers every year; 10 per cent of these cancers are thought to be hereditary.

The decade-long study, which involved scientists and clinicians from 43 centres in 16 countries and was funded by Cancer Research UK, followed nearly 1,000 patients, in some cases for over 10 years. The study found that those who had been taking a regular dose of aspirin had 50 per cent fewer incidents of hereditary cancer compared with those who were not taking aspirin.

The research focused on people with Lynch syndrome which is an inherited genetic disorder that causes cancer by affecting genes responsible for detecting and repairing damage in the DNA. Around 50 per cent of those with Lynch syndrome develop cancer, mainly in the bowel and womb. The study looked at all cancers related to the syndrome, and found that almost 30 per cent of the patients not taking aspirin had developed a cancer compared to around 15 per cent of those taking the aspirin.

Those who had taken aspirin still developed the same number of polyps, which are thought to be precursors of cancer, as those who did not take aspirin but they did not go on to develop cancer. It suggests that aspirin could possibly be causing these cells to destruct before they turn cancerous.

Over 1,000 people were diagnosed with bowel cancer in Northern Ireland last year; 400 of these died from the disease. Ten per cent of bowel cancer cases are hereditary and by taking aspirin regularly the number of those dying from the hereditary form of the disease could be halved.

Professor Patrick Morrison from Queen's University in Belfast, who led the Northern Ireland part of the study, said: "The results of this study, which has been ongoing for over a decade, proves that the regular intake of aspirin over a prolonged period halves the risk of developing hereditary cancers. The effects of aspirin in the first five years of the study were not clear but in those who took aspirin for between five and ten years the results were very clear."

"This is a huge breakthrough in terms of cancer prevention. For those who have a history of hereditary cancers in their family, like bowel and womb cancers, this will be welcome news. Not only does it show we can reduce cancer rates and ultimately deaths, it opens up other avenues for further cancer prevention research. We aim now to go forward with another trial to assess the most effective dosage of aspirin for hereditary cancer prevention and to look at the use of aspirin in the general population as a way of reducing the risk of bowel cancer.

"For anyone considering taking aspirin I would recommend discussing this with your GP first as aspirin is known to bring with it a risk of stomach complaints, including ulcers."

The research was published online Oct. 28 in The Lancet.

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Sir John Burn, Anne-Marie Gerdes, Finlay Macrae, Jukka-Pekka Mecklin, Gabriela Moeslein, Sylviane Olschwang, Diane Eccles, Gareth Evans, Eamonn R. Maher, Lucio Bertario, Marie-Luise Bisgaard, Malcolm G. Dunlop, Judy W.C. Ho, Shirley V. Hodgson, Annika Lindblom, Jan Lubinski, Patrick J. Morrison, Victoria Murday, Raj Ramesar, Lucy Side, Rodney J. Scott, Huw J.W. Thomas, Hans F. Vasen, Gail Barker, Gillian Crawford, Faye Elliott, Mohammad Movahedi, Kirsi Pylvanainen, Juul T. Wijnen, Riccardo Fodde, Henry T. Lynch, John C. Mathers, D. Timothy Bishop, on behalf of the CAPP2 Investigators. Long-term effect of aspirin on cancer risk in carriers of hereditary colorectal cancer: an analysis from the CAPP2 randomised controlled trial. The Lancet, Pubished online Oct. 28, 2011; DOI: 10.1016/S0140-6736(11)61049-0

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Use of over-the-counter thyroid support pills is risky, researcher finds

ScienceDaily (Oct. 27, 2011) — People who use over-the-counter "thyroid support'' supplements may be putting their health at risk, according to a study being presented at the annual meeting of the American Thyroid Association. The supplements contain varying amounts of two different kinds of thyroid hormones apparently derived in large part from chopped up animal thyroid glands, says the study's senior investigator, Victor Bernet, M.D., an endocrinologist at Mayo Clinic in Florida.

The hormones are known as T3, or triiodothyronine, and T4, or thyroxine. They are regulated by the U.S. Food and Drug Administration and intended for use only in prescription medication because they can cause significant health issues, such as an increase in heart rate, heart irregularities and palpitations, nervousness, and diarrhea, Dr. Bernet says.

"These hormones have effects throughout the body, which is why they are controlled," he says.

Not only did nine of the 10 supplements studied have animal hormone, the amount of hormones in the products varied significantly, sometimes exceeding doses used for individual patients and comparable to levels found in prescription thyroid medication, Dr. Bernet says.

The supplements likely do not give most people the results they are seeking, such as weight loss or less fatigue, he says.

"The amount of thyroid hormone a normal person would have to take to lose weight would be dangerously high and there is no evidence that use of thyroid hormone effectively treats fatigue when used in people without actual hypothyroidism," he says.

Because physicians have seen a number of abnormal thyroid tests from patients using over-the-counter supplements, Dr. Bernet became interested in this issue when he heard reports of such cases as chairman of the American Thyroid Association's public health committee. He worked with researchers including endocrinologists at Walter Reed Army Medical Center, where he practiced at the time.

The researchers bought 10 commercially available thyroid supplements from stores or websites and used high-pressure liquid chromatography to separate and identify the chemical components of T3 and T4. Nine of the 10 contained T3 and five of them would deliver as much, or more, than 50 percent of the total amount of T3 produced by the body daily.

Four of the 10 supplements contained T4, and some of those contained a dose that could be twice as much as what an adult needs each day. Only one supplement had no detectable T3 or T4.

The results show there is a need for more effective monitoring of the contents of over-the-counter thyroid support products and more patient education about the products' potential health risks, Dr. Bernet says.

The study was funded by the Department of Clinical Investigation at Walter Reed Army Medical Center, which, in August 2011, became the Walter Reed National Military Medical Center.

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Gender differences: Viewing TV coverage of terrorism has more negative effect on women, study finds

ScienceDaily (Oct. 27, 2011) — Exposure to television coverage of terrorism causes women to lose psychological resources much more than men, which leads to negative feelings and moodiness. This has been shown in a new study, conducted at the University of Haifa and soon to be published in Anxiety, Stress & Coping, that examined the differences between men and women in a controlled experiment environment.

An earlier study conducted by Prof. Moshe Zeidner of the Department of Counseling and Human Development at the University of Haifa and Prof. Hasida Ben-Zur of the University of Haifa's School of Social Work, has shown that viewing television coverage of terrorism causes viewers to lose psychological resources, such the sense of significance or success, and causes a feeling of being threatened. The current study set out to examine whether there are differences between men and women in the levels of psychological resource loss.

According to the authors of the new study, earlier research dealing with gender differences in the effects of traumatic events examined data based on questionnaires relating to past experiences. The present study is now taking a new step as it is examining these differences in a controlled experiment environment in which all of the participants are exposed to the same events and report on their feelings immediately following the events.

In order to create such a controlled environment, men and women were shown news video clips reporting on terrorist attacks that took place over the past few years and which resulted in serious casualties. In parallel, two other groups of men and women were shown news coverage of "regular," everyday news events.

The results of this study show that the women who viewed terrorism coverage testified to higher levels of feeling threatened and lower levels of psychological resources compared to the men who viewed the same news reports. These gender differences were not found amongst the control groups. The study has also found that the feeling of being threatened and loss of resources has an effect on the senses and lead to a higher level of negativity, such as hostility and moodiness.

"It is possible that the differences between men and women are founded in gender socialization, 'teaching' women to respond to terrorism with more anxiety than men," said Prof. Moshe Zeidner.

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Hasida Ben-Zur, Moshe Zeidner. Gender differences in loss of psychological resources following experimentally-induced vicarious stress. Anxiety, Stress & Coping, 2011; DOI: 10.1080/10615806.2011.619526

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Belief in god cuts two ways, study finds

ScienceDaily (Oct. 27, 2011) — Being reminded of the concept of God can decrease people's motivation to pursue personal goals but can help them resist temptation, according to new research published by the American Psychological Association.

"More than 90 percent of people in the world agree that God or a similar spiritual power exists or may exist," said the study's lead author, Kristin Laurin, PhD, of the University of Waterloo in Canada. "This is the first empirical evidence that simple reminders of God can diminish some types of self-regulation, such as pursuing one's goals, yet can improve others, such as resisting temptation."

A total of 353 college students, with an average age 19 and 186 of whom were women, participated in six experiments to determine how the idea of God can indirectly influence people's motivations, even among those who said they were not religious. The students did not have to have an opinion on the existence of a god or any other spiritual power. The findings were reported in the online version of the Journal of Personality and Social Psychology®.

In one experiment, engineering students completed a "warm-up" word task. They were asked to form grammatically correct sentences using four words from sets of five. Some students were provided either God or God-related words (divine, sacred, spirit and prophet), while the control group used more neutral words (ball, desk, sky, track and box). Next, each student had to form as many words as they could in five minutes, using any combination of specific letters. The researchers determined the students' motivation level by the number of words they produced. The more motivated they were, the more words they produced. They were told that a good performance could help predict if they would succeed in an engineering career.

Several weeks before this experiment, the students had been asked if they believed outside factors (other people, beings, forces beyond their control) had an influence on their careers. Among participants who said outside factors such as God might influence their career success, those who did the God-related word task performed worse than those who used neutral words. There was no difference in performance among the participants who did not believe outside factors influenced their career success.

Researchers also measured the importance participants placed on a number of values, including achievement. Participants reminded of God placed the same value on achievement as did participants primed with the more neutral words. "This suggests that our findings did not emerge because the participants reminded of God devalued achievement," said Laurin.

A second set of experiments looked at participants' ability to resist temptation after being reminded about God. In one study, participants who said eating healthy food was important to them ate fewer cookies after reading a short passage about God than those who read a passage unrelated to God.

Participants who read a short God-related passage reported greater willingness to resist temptations to achieve a major goal, such as maintaining a healthy weight, finding a long-term relationship or having a successful career. This effect was found only among participants who had previously said they believe an omniscient entity watches over them and notices when they misbehave.

The level of participants' religious devotion had no impact on the outcomes in any of the experiments, according to the researchers.

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Kristin Laurin, Aaron C. Kay, Gráinne M. Fitzsimons. Divergent effects of activating thoughts of god on self-regulation. Journal of Personality and Social Psychology, 2011; DOI: 10.1037/a0025971

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