terça-feira, 20 de janeiro de 2015

Red wine and resveratrol: Good for your heart?

 

 

Red wine and something in red wine called resveratrol might be heart healthy. Find out the facts, and hype, regarding red wine and its impact on your heart.

By Mayo Clinic Staff

Red wine, in moderation, has long been thought of as heart healthy. The alcohol and certain substances in red wine called antioxidants may help prevent heart disease by increasing levels of high-density lipoprotein (HDL) cholesterol (the "good" cholesterol) and protecting against artery damage.

While the news about red wine might sound great if you enjoy a glass of red wine with your evening meal, doctors are wary of encouraging anyone to start drinking alcohol. That's because too much alcohol can have many harmful effects on your body.

Still, many doctors agree that something in red wine appears to help your heart. It's possible that antioxidants, such as flavonoids or a substance called resveratrol, have heart-healthy benefits.

How is red wine heart healthy?

Red wine seems to have even more heart-healthy benefits than do other types of alcohol, but it's possible that red wine isn't any better than beer, white wine or liquor for heart health. There's still no clear evidence that red wine is better than other forms of alcohol when it comes to possible heart-healthy benefits.

Antioxidants in red wine called polyphenols may help protect the lining of blood vessels in your heart. A polyphenol called resveratrol is one substance in red wine that's gotten attention.

Resveratrol in red wine

Resveratrol might be a key ingredient in red wine that helps prevent damage to blood vessels, reduces low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol) and prevents blood clots.

Most research on resveratrol has been done on animals, not people. Research in mice given resveratrol suggests that the antioxidant might also help protect them from obesity and diabetes, both of which are strong risk factors for heart disease. However, those findings were reported only in mice, not in people. In addition, to get the same dose of resveratrol used in the mice studies, a person would have to drink more than 1,000 liters of red wine every day. Research in pigs has shown that resveratrol may improve heart function and increase the body's ability to use insulin. Again, however, these benefits have not been tested in people.

Some research shows that resveratrol could be linked to a reduced risk of inflammation and blood clotting, both of which can lead to heart disease. More research is needed before it's known whether resveratrol was the cause for the reduced risk. However, one study showed that resveratrol may actually reduce the positive effect of exercise on the heart in older men. It's also important to know that resveratrol's effects only last a short time after drinking red wine, so its effects may not last in the long term.

  • Resveratrol in grapes, supplements and other foods

The resveratrol in red wine comes from the skin of grapes used to make wine. Because red wine is fermented with grape skins longer than is white wine, red wine contains more resveratrol. Simply eating grapes, or drinking grape juice, has been suggested as one way to get resveratrol without drinking alcohol. Red and purple grape juices may have some of the same heart-healthy benefits of red wine.

Other foods that contain some resveratrol include peanuts, blueberries and cranberries. It's not yet known how beneficial eating grapes or other foods might be compared with drinking red wine when it comes to promoting heart health. The amount of resveratrol in food and red wine can vary widely.

Resveratrol supplements also are available. While researchers haven't found any harm in taking resveratrol supplements, most of the resveratrol in the supplements can't be absorbed by your body.

How does alcohol help the heart?

Various studies have shown that moderate amounts of all types of alcohol benefit your heart, not just alcohol found in red wine. It's thought that alcohol:

  • Raises high-density lipoprotein (HDL) cholesterol, the "good" cholesterol
  • Reduces the formation of blood clots
  • Helps prevent artery damage caused by high levels of low-density lipoprotein (LDL) cholesterol, the "bad" cholesterol
  • Produces changes in blood pressure
Drink in moderation — or not at all

Red wine's potential heart-healthy benefits look promising. Those who drink moderate amounts of alcohol, including red wine, seem to have a lower risk of heart disease. However, more research is needed before we know whether red wine is better for your heart than are other forms of alcohol, such as beer or spirits.

Neither the American Heart Association nor the National Heart, Lung, and Blood Institute recommend that you start drinking alcohol just to prevent heart disease. Alcohol can be addictive and can cause or worsen other health problems.

Drinking too much alcohol increases your risk of high blood pressure, high triglycerides, liver damage, obesity, certain types of cancer, accidents and other problems. In addition, drinking too much alcohol regularly can cause weakened heart muscle (cardiomyopathy), leading to symptoms of heart failure in some people. If you have heart failure or a weak heart, you should avoid alcohol completely. If you take aspirin daily, you should avoid or limit alcohol, depending on your doctor's advice. You also shouldn't drink alcohol if you're pregnant. If you have questions about the benefits and risks of alcohol, talk to your doctor about specific recommendations for you.

If you already drink red wine, do so in moderation. For healthy adults, that means up to one drink a day for women of all ages and men older than age 65, and up to two drinks a day for men age 65 and younger. The limit for men is higher because men generally weigh more and have more of an enzyme that metabolizes alcohol than women do.

A drink is defined as 12 ounces (355 milliliters, or mL) of beer, 5 ounces (148 mL) of wine or 1.5 ounces (44 mL) of 80-proof distilled spirits.

Apr. 25, 2014
References

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Sitting for long periods increases risk of disease and early death, regardless of exercise

 

 

The amount of time a person sits during the day is associated with a higher risk of heart disease, diabetes, cancer, and death, regardless of regular exercise.

The amount of time a person sits during the day is associated with a higher risk of heart disease, diabetes, cancer, and death, regardless of regular exercise, according to a review study published today in the Annals of Internal Medicine.

"More than one half of an average person's day is spent being sedentary -- sitting, watching television, or working at a computer," said Dr. David Alter, Senior Scientist, Toronto Rehab, University Health Network (UHN), and Institute for Clinical Evaluative Sciences. "Our study finds that despite the health-enhancing benefits of physical activity, this alone may not be enough to reduce the risk for disease."

The meta-analysis study reviewed studies focused on sedentary behaviour. The lead author is Avi Biswas, PhD candidate, Toronto Rehab, UHN and the Institute of Health Policy, Management and Evaluation, University of Toronto, and the senior author is Dr. Alter, who is also Associate Professor of Medicine, University of Toronto.

The authors found the negative effects of sitting time on health, however, are more pronounced among those who do little or no exercise than among those who participate in higher amounts of exercise.

"The findings suggest that the health risk of sitting too much is less pronounced when physical activity is increased," said Biswas. "We need further research to better understand how much physical activity is needed to offset the health risks associated with long sedentary time and optimize our health."

Future research will help determine what interventions, in addition to physical activity, are effective against the health risk of sedentary time.

"Avoiding sedentary time and getting regular exercise are both important for improving your health and survival," said Dr. Alter. "It is not good enough to exercise for 30 minutes a day and be sedentary for 23 and half hours."

In the interim, Dr. Alter underlines strategies people can use to reduce sitting time. The target is to decrease sedentary time by two to three hours in a 12-hour day.

"The first step is to monitor sitting times -- once we start counting, we're more likely to change our behaviour," said Dr. Alter. "Next is setting achievable goals and finding opportunities to incorporate greater physical activity -- and less time sitting -- into your daily life. For example, at work, stand up or move for one to three minutes every half hour; and when watching television, stand or exercise during commercials."

Dr. Alter's work is supported by a career-investigator award with the Heart and Stroke Foundation, Ontario Provincial Office; and a Research Chair in Cardiovascular Prevention and Metabolic Rehabilitation at Toronto Rehab, UHN.


Story Source:

The above story is based on materials provided by University Health Network (UHN). Note: Materials may be edited for content and length.


Journal Reference:

  1. Aviroop Biswas, Paul I. Oh, Guy E. Faulkner, Ravi R. Bajaj, Michael A. Silver, Marc S. Mitchell, and David A. Alter. Sedentary Time and Its Association With Risk for Disease Incidence, Mortality, and Hospitalization in Adults: A Systematic Review and Meta-analysis. Annals of Internal Medicine, 2015 DOI: 10.7326/M14-1651

 

domingo, 18 de janeiro de 2015

Pre-sleep drinking disrupts sleep

 

January 17, 2015

Alcoholism: Clinical & Experimental Research

For individuals who drink before sleeping, alcohol initially acts as a sedative -- marked by the delta frequency electroencephalogram (EEG) activity of Slow Wave Sleep (SWS) -- but is later associated with sleep disruption. A study of the effects of alcohol on sleep EEG power spectra in college students has found that pre-sleep drinking not only causes an initial increase in SWS-related delta power but also causes an increase in frontal alpha power, which is thought to reflect disturbed sleep.


For individuals who drink before sleeping, alcohol initially acts as a sedative -- marked by the delta frequency electroencephalogram (EEG) activity of Slow Wave Sleep (SWS) -- but is later associated with sleep disruption. Significant reductions in EEG delta frequency activity and power also occur with normal development between the ages of 12 and 16; likewise this is a time when alcohol is commonly consumed for the first time, with dramatic increases in drinking occurring among collage-age individuals. A study of the effects of alcohol on sleep EEG power spectra in college students has found that pre-sleep drinking not only causes an initial increase in SWS-related delta power but also causes an increase in frontal alpha power, which is thought to reflect disturbed sleep.

Results will be published in the February 2015 online-only issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.

"People likely tend to focus on the commonly reported sedative properties of alcohol, which is reflected in shorter times to fall asleep, particularly in adults, rather than the sleep disruption that occurs later in the night," said Christian L. Nicholas, National Health & Medical Research Council Peter Doherty Research Fellow in the Sleep Research Laboratory at The University of Melbourne as well as corresponding author for the study.

"The reduction in delta frequency EEG activity we see across the ages is thought to represent normal brain maturational processes as the adolescent brain continues to develop to full maturity," said Nicholas. "Although the exact function of non-Rapid Eye Movement (NREM) sleep, and in particular SWS, is a topic of debate, it is thought to reflect sleep need and quality; thus any disruption to this may affect the underlying restorative properties of sleep and be detrimental to daytime functioning."

Nicholas and his colleagues recruited 24 participants (12 female, 12 male), healthy 18- to 21-year-old social drinkers who had consumed less than seven standard drinks per week during the previous 30 days. Each participant underwent two conditions: pre-sleep alcohol as well as a placebo, followed by standard polysomnography with comprehensive EEG recordings.

Results showed that alcohol increased SWS delta power during NREM. However, there was a simultaneous increase in frontal alpha power.

"For individuals researching sleep in the field of alcohol studies," said Nicholas, "our findings indicate that care needs to be taken when interpreting increases in 'visually scored' SWS associated with alcohol consumption. Increases in SWS, which traditionally would be interpreted as a good thing, can be associated with more subtle changes indicating disrupted sleep, such as the increases we observed in alpha activity, which are revealed when more detailed micro-structural components of the sleep electroencephalogram are assessed."

Nicholas explained that the increase in frontal alpha power that occurs as a result of pre-sleep drinking likely reflects a disruption of the normal properties of NREM slow wave sleep.

"Similar increases in alpha-delta activity, which are associated with poor or unrefreshing sleep and daytime function, have been observed in individuals with chronic pain conditions," he said. "Thus, if sleep is being disrupted regularly by pre-sleep alcohol consumption, particularly over long periods of time, this could have significant detrimental effects on daytime wellbeing and neurocognitive function such as learning and memory processes."

Alcohol is not a sleep aid, said Nicholas. "The take-home message here is that alcohol is not actually a particularly good sleep aid even though it may seem like it helps you get to sleep quicker. In fact, the quality of the sleep you get is significantly altered and disrupted."


Story Source:

The above story is based on materials provided by Alcoholism: Clinical & Experimental Research. Note: Materials may be edited for content and length.


Journal Reference:

  1. Julia K. M. Chan, John Trinder, Ian M. Colrain, Christian L. Nicholas. The Acute Effects of Alcohol on Sleep Electroencephalogram Power Spectra in Late Adolescence. Alcoholism: Clinical and Experimental Research, 2015; DOI: 10.1111/acer.12621

 

Exploring the use of alcohol-interactive prescription medication among US drinkers

January 17, 2015

Alcoholism: Clinical & Experimental Research

Approximately 71 percent of people in the US (adults) drink alcohol. While alcohol interacts negatively with a number of commonly prescribed medications, little is known on a population level about the use of alcohol-interactive prescription medication among US drinkers. A new study has found that almost 42 percent of drinkers in the US population have used one or more alcohol-interactive prescription medications.


While alcohol interacts negatively with a number of commonly prescribed medications, little is known on a population level about the use of alcohol-interactive (AI) prescription medication among US drinkers. A new study has found that almost 42 percent of drinkers in the US population have used one or more alcohol-interactive prescription medications.

Results will be published in the February 2015 online-only issue of Alcoholism: Clinical & Experimental Research and are currently available at Early View.

"To our knowledge there have been only four previous US population-based studies," said Rosalind A. Breslow, an epidemiologist in the division of epidemiology and prevention research at the National Institute on Alcohol Abuse and Alcoholism as well as corresponding author for the study. "Three, conducted only among elderly people, concluded that substantial numbers of seniors were both drinking and taking alcohol-interactive medications and called for increased awareness about possible harmful consequences. One, conducted among adults of all ages, had a similar conclusion based on assessment of a limited number of prescription medications. Ours is a national-level study that estimates the proportion of adult drinkers who use a wide range of prescription medications that can interact with alcohol to cause numerous harms ranging from nausea, headaches, and loss of coordination to internal bleeding, heart problems, and difficulties in breathing."

Breslow added that her group expected to find greater prevalence among older drinkers. "People develop more chronic diseases as they age," she said, "so older people are more likely to be taking medications, many of which can interact harmfully with alcohol. They also may be taking multiple medications to treat multiple diseases. In addition, older people are at particularly high risk for harmful alcohol-medication interactions. There is some evidence that, as we age, our ability to metabolize alcohol decreases so alcohol might remain in our systems longer to interact with medications. Furthermore, the metabolism of several medications that interact with alcohol slows as we get older, creating a larger window for potential alcohol/medication interactions. For instance, diazepam -- known as Valium -- hangs around in the body about three times longer in a 60-year-old than a 20-year-old, thereby creating a much longer window for potential interactions with alcohol."

Breslow and her co-authors examined data from the 1999-2010 National Health and Nutrition Examination Survey, in which 26,657 adults (13,557 men, 13,100 women) aged ?20 years had provided data on past-year alcohol consumption and past-month prescription medication use. Analyses were adjusted for age, race/ethnicity, education, marital status, and smoking, and were also weighted in order to be nationally representative.

"Almost 42 percent of drinkers in the US population used one or more AI prescription medications," said Breslow. "Among seniors, aged 65 and older, the proportion was even higher, almost 78 percent. Regardless of age, the main therapeutic classes of AI medications used in the population were cardiovascular agents such as blood pressure medications, central nervous system agents such as sleeping pills, pain medications, and muscle relaxers, metabolic agents such as medications for diabetes and cholesterol, and psychotherapeutic agents such as antidepressants and antipsychotics."

Breslow noted that her group had expected a high prevalence rate, however, she emphasized that the data referred to potential, not actual, prevalence. "The data don't tell us exactly how many people in that 41.5 percent actually drink and take their medications within a similar time frame or how often they do so," she said. "However, if someone drinks regularly and takes medications regularly, the likelihood of taking them within a similar time frame is pretty high."

According to co-author Aaron White, a neuroscientist in the division of epidemiology and prevention research at the National Institute on Alcohol Abuse and Alcoholism, the consequences of mixing prescription medications with alcohol can have a variety of effects, some deadly.

"Alcohol can increase blood pressure, which could be counterproductive if one is taking medications to control blood pressure," he explained. "Mixing diuretic medications with alcohol, which is also a diuretic, could contribute to dehydration. Mixing alcohol and other sedatives, like sleeping pills or narcotic pain medications, can cause sleepiness, problems with coordination, and potentially suppress brain stem areas tasked with controlling vital reflexes like breathing, heart rate, and gagging to clear the airway. Alcohol increases insulin levels and lowers blood glucose, so combining alcohol with antidiabetic agents that regulate glucose levels could cause an undesirable drop in blood sugar. And, over time, alcohol can contribute to insulin insensitivity."

"Our findings highlight a major gap in the literature," said Breslow. "We found no US nationally representative data that queried combined use of alcohol with a wide range of prescription medications and yet it appears that a large percentage of people who drink regularly could be at risk of serious alcohol and medication interactions."

Breslow suggested that individuals who drink, particularly the elderly, should be educated about of the risks of combining alcohol with their medications. "We suggest asking one's doctor or pharmacist whether they should avoid alcohol while taking the medications they are prescribed," she said.


Story Source:

The above story is based on materials provided by Alcoholism: Clinical & Experimental Research. Note: Materials may be edited for content and length.


Journal Reference:

  1. Rosalind A. Breslow, Chuanhui Dong, Aaron White. Prevalence of Alcohol-Interactive Prescription Medication Use Among Current Drinkers: United States, 1999 to 2010. Alcoholism: Clinical and Experimental Research, 2015; DOI: 10.1111/acer.12633

 

Breakthrough lights up metamaterials

 

 


This is a schematic of active metamaterial which shows enhanced light emission and extraction.

A City College of New York led-team has successfully demonstrated how to both enhance light emission and capture light from metamaterials embedded with light emitting nanocrystals. The breakthrough, headed by physicist Dr. Vinod Menon, could lead to a range of applications including ultrafast LEDs, nanoscale lasers and efficient single photon sources.

In the demonstration, the team used metamaterials having hyperbolic dispersion to enhance the light emission properties of the nanocrystals and simultaneously engineered an efficient light extraction scheme.

"The idea of metamaterials in the context of optics is that you can manipulate light and decide how you want it to behave in this medium," said Professor Menon a photonics expert whose specialty includes control of light-matter interaction at the nanoscale.

While enhancement in light emission from such systems was shown by different groups, including Dr. Menon's, in the past, they were not useful since light did not come out easily from them, making their practical application an issue. The present work alleviates this issue and takes the first step towards developing practical light emitters based on metamaterials.

"We've shown both an increase in light emission and were able to extract light." added Professor Menon, whose team included City College PhD students Tal Galfsky and H.N.S. Krishnamoothy

Also part of the research team were scientists from the University of Alberta (Canada), Purdue University in Indiana. Part of the research was also carried out at the Center for Functional Nanomaterials at Brookhaven National Laboratory.

The paper appears in the latest issue of Optica.


Story Source:

The above story is based on materials provided by City College of New York. Note: Materials may be edited for content and length.


Journal Reference:

  1. T. Galfsky, H. N. S. Krishnamoorthy, W. Newman, E. E. Narimanov, Z. Jacob, V. M. Menon. Active hyperbolic metamaterials: enhanced spontaneous emission and light extraction. Optica, 2015; 2 (1): 62 DOI: 10.1364/OPTICA.2.000062

 

NEOWISE: A yearlong look at the sky

 

This movie shows the progression of NASA's NEOWISE survey in the mission's first year following its restart in December 2013.

NASA's Near-Earth Object Wide-field Survey Explorer (NEOWISE) spacecraft discovered and characterized 40 near-Earth objects (NEOs) in the first year after the mission was re-started in December 2013. Eight of the discoveries have been classified as potentially hazardous asteroids (PHAs), based on their size and how close their orbits could come to Earth's orbit.

The mission has further observed and characterized 245 previously known near-Earth objects. From December 2013 to December 2014, NEOWISE discovered three new comets and observed 32 others. One of the others has turned into the brightest comet in Earth's night sky in early 2015, comet C/2014 Q2 (Lovejoy).

A new movie depicts asteroids and comets observed in the past year by NEOWISE. It is online at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA19101

A series of NEOWISE images of comet Lovejoy is online at:

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA19102

NEOWISE always looks in the dawn and twilight skies -- the direction perpendicular to a line between Earth and the sun. This unique vantage point makes it easy for NEOWISE to spot NEOs that get particularly close to Earth.

Originally called the Wide-field Infrared Survey Explorer (WISE), the spacecraft was placed in hibernation in 2011 after its primary mission was completed. In September 2013, it was reactivated, renamed NEOWISE and assigned a new mission to assist NASA's efforts to identify the population of potentially hazardous near-Earth objects. NEOWISE is also characterizing previously known asteroids and comets to provide information about their sizes and compositions.

NEOWISE is a space telescope that scans the skies for asteroids and comets. The telescope sees infrared light, which allows it to pick up the heat signature of asteroids and obtain better estimates of their true sizes. As a result, NEOWISE can see dark asteroids that are harder for visible-light surveys to find. Nearly all of the NEOWISE discoveries have been large (hundreds of yards, or meters, wide) and very dark, similar to printer toner. When NEOWISE's infrared data on an object is combined with that of a visible-light optical telescope, it helps scientists understand the object's composition.

NASA's Jet Propulsion Laboratory in Pasadena, California, manages the NEOWISE mission for NASA's Science Mission Directorate in Washington. The Space Dynamics Laboratory in Logan, Utah, built the science instrument. Ball Aerospace & Technologies Corp. of Boulder, Colorado, built the spacecraft. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. For more information about NEOWISE, visit:

http://www.nasa.gov/neowise

More information about asteroids and near-Earth objects is at:

http://www.jpl.nasa.gov/asteroidwatch


Story Source:

The above story is based on materials provided by NASA/Jet Propulsion Laboratory. Note: Materials may be edited for content and length.


 

Sentences that can change your life

 

1. Never compare your weaknesses to other people's strengths.
2. Own your life, or someone will own it for you.
3.  We cannot change the cards we are dealt,just how we play the hand.
4. Climb mountains not so the world can see you but so you can see the world.
5. If you accept your limitation, you go beyond them.
6. Comfort is the enemy of achievement.
7. No matter anyone says to you,you don't have to eat dinner with them,
live with them or go to bed with them.
8. If you risk nothing, you risk everything.
9. Don't give others the power to control your emotion. Those are only yours and it is only for you to manipulate.
10. Victory introduces you to the world, but defeat introduces the world to you.
11. If you don't do stupid things while you are young,you will have nothing to smile about when you are old.
12. Don't waste your time with explanation,people only hear what they want to hear.
13. Don't rest after your first victory,because if you fail the second time,more lips will be waiting to say that your first victory was just luck.
14. Everyone thinks of changing the world,but no one thinks of changing themselves.
15. The person that you will spend most time with in your life is yourself, so better try to make yourself as interesting as possible.
Source :
Sentences that Can Change Your Life - Lifehack

A Happiness Tip From Aristotle

 

Do you know the difference between pleasure vs. happiness?

by Karen Salmansohn in Bouncing Back

Quickie Question: If you could live 10 years of your life in total bliss - with NO pain - but in the end, not remember any of it - would you do it?

According to Aristotle - the answer should be NO.

My favorite philosopher buddy Aristotle says true happiness comes from gaining insight and growing into your best possible self. Otherwise all you’re having is immediate gratification pleasure - which is fleeting and doesnt grow you as a person.

In a way the above scenario is a description of someone who does crack or drinks into oblivion. At the time it feels like you’re avoiding pain and seeking bliss - but in longterm you’re NOT really enjoying real life — with life’s inevitable ebbs and flows which give you needed insights and exciting experiences which grow you and let you know more about who you are and what you love and who you truly love!

Aristotle has a wonderful quote related to this topic:

“We live in deeds, not years; in thoughts not breaths; in feelings, not in figures on a dial. We should count time by heart throbs. He most lives who thinks most, feels the noblest, acts the best.”

Translation: I intuit what Aristotle was saying is that life has ebbs and flows. There’s no such thing as endless flow. Unfortunately life can sometimes feel like ebb, ebb, ebb, brief-flash-of-flow, more ebb, ebb, ebb. But every ebb always offers the opportunity to think a new thought flavor and feel a new emotion flavor. The more varied the flavors of life you get to taste, the more interesting, layered, educated, self-developed, world-experienced and mightier You will be!

In keeping with this theme, Aristotle believed the highest form of knowledge is insight - because it's the only knowledge which leads to growth - and evolving into your highest potential is what leads to true happiness.

For this reason, Aristotle believed that the reason why so many people are unhappy is that they keep foolishly confusing "pleasure" for "happiness." "Pleasure" is simply about immediate gratification -- of your body/ego. "Happiness" is about seeking longterm growth for yourself as a thriving individual - and is about nourishing your soul/core self.

sábado, 17 de janeiro de 2015

Three nearly Earth-size planets found orbiting nearby star: One in 'Goldilocks' zone

 

NASA's Kepler Space Telescope, despite being hobbled by the loss of critical guidance systems, has discovered a star with three planets only slightly larger than Earth. The outermost planet orbits in the "Goldilocks" zone, a region where surface temperatures could be moderate enough for liquid water and perhaps life, to exist.

The star, EPIC 201367065, is a cool red M-dwarf about half the size and mass of our own sun. At a distance of 150 light years, the star ranks among the top 10 nearest stars known to have transiting planets. The star's proximity means it's bright enough for astronomers to study the planets' atmospheres to determine whether they are like Earth's atmosphere and possibly conducive to life.

"A thin atmosphere made of nitrogen and oxygen has allowed life to thrive on Earth. But nature is full of surprises. Many exoplanets discovered by the Kepler mission are enveloped by thick, hydrogen-rich atmospheres that are probably incompatible with life as we know it," said Ian Crossfield, the University of Arizona astronomer who led the study.

A paper describing the find by astronomers at the University of Arizona, the University of California, Berkeley, the University of Hawaii, Manoa, and other institutions has been submitted to Astrophysical Journal and is freely available on the arXiv website . NASA and the National Science Foundation funded the research.

Co-authors of the paper include Joshua Schlieder of NASA Ames Research Center and colleagues from Germany, the United Kingdom and the U.S.

The three planets are 2.1, 1.7 and 1.5 times the size of Earth. The smallest and outermost planet, at 1.5 Earth radii, orbits far enough from its host star that it receives levels of light from its star similar to those received by Earth from the sun, said UC Berkeley graduate student Erik Petigura. He discovered the planets Jan. 6 while conducting a computer analysis of the Kepler data NASA has made available to astronomers. In order from farthest to closest to their star, the three planets receive 10.5, 3.2 and 1.4 times the light intensity of Earth, Petigura calculated.

"Most planets we have found to date are scorched. This system is the closest star with lukewarm transiting planets," Petigura said. "There is a very real possibility that the outermost planet is rocky like Earth, which means this planet could have the right temperature to support liquid water oceans."

University of Hawaii astronomer Andrew Howard noted that extrasolar planets are discovered by the hundreds these days, though many astronomers are left wondering if any of the newfound worlds are really like Earth. The newly discovered planetary system will help resolve this question, he said.

"We've learned in the past year that planets the size and temperature of Earth are common in our Milky Way galaxy," Howard said. "We also discovered some Earth-size planets that appear to be made of the same materials as our Earth, mostly rock and iron."

Kepler's K2 mission

After Petigura found the planets in the Kepler light curves, the team quickly employed telescopes in Chile, Hawaii and California to characterize the star's mass, radius, temperature and age. Two of the telescopes involved, the Automated Planet Finder on Mount Hamilton near San Jose, California, and the Keck Telescope on Mauna Kea, Hawaii, are University of California facilities.

The next step will be observations with other telescopes, including the Hubble Space Telescope, to take the spectroscopic fingerprint of the molecules in the planetary atmospheres. If these warm, nearly Earth-size planets have puffy, hydrogen-rich atmospheres, Hubble will see the telltale signal, Petigura said.

The discovery is all the more remarkable, he said, because the Kepler telescope lost two reaction wheels that kept it pointing at a fixed spot in space.

Kepler was reborn in 2014 as 'K2' with a clever strategy of pointing the telescope in the plane of Earth's orbit, the ecliptic, to stabilize the spacecraft. Kepler is now back to mining the cosmos for planets by searching for eclipses or "transits," as planets pass in front of their host stars and periodically block some of the starlight.

"This discovery proves that K2, despite being somewhat compromised, can still find exciting and scientifically compelling planets," Petigura said. "This ingenious new use of Kepler is a testament to the ingenuity of the scientists and engineers at NASA. This discovery shows that Kepler can still do great science."

Kepler sees only a small fraction of the planetary systems in its gaze: only those with orbital planes aligned edge-on to our view from Earth. Planets with large orbital tilts are missed by Kepler. A census of Kepler planets the team conducted in 2013 corrected statistically for these random orbital orientations and concluded that one in five sun-like stars in the Milky Way Galaxy have Earth-size planets in the habitable zone. Accounting for other types of stars as well, there may be 40 billion such planets galaxy wide.

The original Kepler mission found thousands of small planets, but most of them were too faint and far away to assess their density and composition and thus determine whether they were high-density, rocky planets like Earth or puffy, low-density planets like Uranus and Neptune. Because the star EPIC-201 is nearby, these mass measurements are possible. The host star, an M-dwarf, is less intrinsically bright than the sun, which means that its planets can reside close to the host-star and still enjoy lukewarm temperatures.

According to Howard, the system most like that of EPIC-201 is Kepler-138, an M-dwarf star with three planets of similar size, though none are in the habitable zone.

sexta-feira, 16 de janeiro de 2015

2,500-year-old Pythagoras theorem helps to show when a patient has turned a corner

 

A medical researcher at the University of Warwick has found the 2,500 year-old Pythagoras theorem could be the most effective way to identify the point at which a patient's health begins to improve.

In a paper published in PLOS ONE, Dr Rob Froud from Warwick Medical School at the University of Warwick worked with his colleague Gary Abel from the University of Cambridge. They made the discovery after looking at data from ROC (Receiver Operating Characteristic) curves. These curves were initially developed during World War II for the analysis of signals to help operators decide whether a blip on the screen was an enemy target or allied forces ships or aircrafts. In the 1980s, the curves were adopted by epidemiologists to help them decide at what point an individual has recovered from an illness.

Dr Froud said: "It all comes down to choosing a point on a curve to determine when recovery has occurred. For many chronic conditions, epidemiologists agree that the correct point to choose is that which is closest to the top-left corner of the plot containing the curve. As we stopped to think about it, it struck us as obvious that the way to choose this point was by using Pythagoras theorem."

Pythagoras theorem states that in a right-angled triangle, the sum of the squares of the two right-angled sides is equal to the square of the hypotenuse (i.e the longer diagonal that joins the two right angled sides). This means that one can determine the length of the hypotenuse given the length of the other two sides.

Dr Froud said: "We set about exploring the implications of this and how it might change conclusions in research. We conducted several experiments using real trial data and it seems using Pythagoras' theorem makes a material difference. It helps to identify the point at which a patient has improved with more consistency and accuracy than other methods commonly used.

"The moral of the story is that before you throw out the old stuff in the attic -- just go through it one last time -- as there may be something in there that is still relevant and useful," Dr Froud added.


Story Source:

The above story is based on materials provided by University of Warwick. Note: Materials may be edited for content and length.


Journal Reference:

  1. Robert Froud, Gary Abel. Using ROC Curves to Choose Minimally Important Change Thresholds when Sensitivity and Specificity Are Valued Equally: The Forgotten Lesson of Pythagoras. Theoretical Considerations and an Example Application of Change in Health Status. PLoS ONE, 2014; 9 (12): e114468 DOI: 10.1371/journal.pone.0114468