Tag: 上海鸡多的酒吧

Alien worlds, just like home

Alien worlds, just like home

first_imgHarvard astronomers, working as part of NASA’s Kepler mission, have detected the first Earth-sized planets orbiting a distant star, a milestone in the hunt for alien worlds that brings scientists a step closer to their ultimate goal of finding a twin to Earth.Described in the Dec. 20 issue of the journal Nature, the two planets, dubbed Kepler-20e and Kepler-20f, are the smallest planets found by the Kepler mission to date. They have diameters of 6,900 miles and 8,200 miles — equivalent to 0.87 times Earth (slightly smaller than Venus) and 1.03 times Earth. These worlds are expected to have rocky compositions, so their masses should be, respectively, approximately 1.7 and 3 times Earth’s.“The goal of Kepler is to find Earth-sized planets in the habitable zone. Proving the existence of Earth-sized exoplanets is a major step toward achieving that goal,” said Francois Fressin, a research associate at the Harvard-Smithsonian Center for Astrophysics (CfA).Both worlds circle Kepler-20, a star located 950 light-years from Earth. Though that star is slightly cooler than the Sun, the planets’ tight orbits — Kepler-20e orbits every 6.1 days at a distance of 4.7 million miles, while Kepler-20f orbits every 19.6 days at a distance of 10.3 million miles — they are heated to temperatures of 1,400 and 800 degrees Fahrenheit, respectively.In addition to the two newfound worlds, the Kepler-20 system contains three previously identified planets. All five have orbits closer than Mercury in our solar system, and show an unexpected arrangement. In our solar system, small, rocky worlds orbit close to the Sun, while large, gas, giant ones orbit farther out. In contrast, the planets of Kepler-20 are organized in alternating size: big, little, big, little, big.“We were surprised to find this system of flip-flopping planets,” said David Charbonneau, professor of astronomy and a co-author of the Nature paper. “It’s very different than our solar system.”The three largest planets are designated Kepler-20b, Kepler-20c, and Kepler-20d. They have diameters of 15,000, 24,600, and 22,000 miles, and orbit once every 3.7, 10.9, and 77.6 days, respectively.In the hunt for planets, Kepler identifies “objects of interest” by looking for stars that dim slightly, which can occur when a planet crosses the star’s face. Such dimming, however, could be caused by a variety of phenomena. To determine whether an object truly is a planet, astronomers use Blender, a software package developed by Fressin and Willie Torres of CfA. After running millions of possible simulations, the team concluded that the odds are strongly in favor of Kepler-20e and Kepler-20f being planets.Fressin and Torres also used Blender to confirm the existence of Kepler-22b, a planet in the habitable zone of its star that was announced by NASA earlier this month. However, that world was much larger than Earth.“These new planets are significantly smaller than anything found up till now orbiting a sunlike star,” added Fressin.last_img read more

The cellular origin of fibrosis

The cellular origin of fibrosis

first_imgHarvard Stem Cell Institute scientists at Brigham and Women’s Hospital say they have found the cellular origin of the tissue scarring caused by organ damage associated with diabetes, lung disease, high blood pressure, kidney disease, and other conditions.The buildup of scar tissue, known as fibrosis, has a number of consequences, including inflammation and reduced blood and oxygen delivery to the organ. Long term, the scar tissue can lead to organ failure and sometimes eventually death. It is estimated that fibrosis contributes to 45 percent of all deaths in the developed world.The researchers, led by Benjamin Humphreys, found that in mice, a rare population of stem cells located outside of blood vessels become myofibroblast cells that secrete proteins that cause scar tissue. Killing these stem cells prevents the deadly complications of fibrosis, the researchers report today in the journal Cell Stem Cell online. Rafael Kramann, a postdoctoral fellow in Humphreys’ lab, is the first author on the paper.“Under normal circumstances, myofibroblasts stimulate wound healing, but when there’s an ongoing injury to an organ [such as the liver of a hepatitis C patient, the heart of a patient with high blood pressure, or the kidney of a patient with diabetes], these proteins clog up normal functioning,” said Humphreys, a Harvard Medical School associate professor at the Brigham, who leads the Harvard Stem Cell Institute Kidney Program.The researchers are now in discussions with a pharmaceutical firm about screening for drugs that might target and shut off these fibrosis-causing stem cells in cases of chronic organ disease. The idea of using the stem cells as targets for drug discovery began with the formation — by Humphreys, Kramann, and Derek DiRocco — of MatriTarg Laboratories, the startup that won the 2013 Harvard Deans’ Health and Life Sciences Challenge.“We wanted to know if eradication of this very small population of stem cells would improve organ function, and both kidney and heart were completely protected from developing fibrosis-related complications [such as kidney failure and heart failure],” said Humphreys, who also heads the Onco-Nephrology Program at the Dana-Farber Cancer Institute. “This provides an important proof of principle that drugs that target the stem cells could be therapeutic.”The cellular origin of kidney fibrosis has long puzzled researchers. It was unknown which kinds of stem cells form myofibroblasts, and where these stem cells are located. One long-held hypothesis was that the stem cells that give rise to myofibroblasts are found in the bone marrow, but Humphreys’ research disproves that. By tagging a specific protein called Gli1 expressed by the myofibroblast-forming stem cells, the scientists showed that the cells are found on the periphery of blood vessels, and also reside within organs.Humphreys does caution that the cell population his lab found is responsible for about 60 percent of all organ myofibroblasts, which means that they seem to be the most dominant source, but there may be other cells that also contribute to the myofibroblast population.“We haven’t disproven every hypothesis, and our results do leave room for other cells that might contribute to fibrosis,” he said.The Humphreys Lab collaborated with fellow Harvard Stem Cell Institute member Benjamin Ebert, an associate professor of medicine at Brigham and Women’s Hospital, on the work.The research was supported by the Harvard Stem Cell Institute, the National Institutes of Health, the National Institute of Diabetes and Digestive and Kidney Diseases, the American Heart Association, and the Deutsche Forschungsgemeinschaft.last_img read more

Morning-after pill use rises in US

Morning-after pill use rises in US

first_img Sharing is caring! 25 Views   no discussions Share Tweet Use of the morning-after pill in the US is on the rise, a trend driven largely by wider use among younger women, a major government study has found.Some 11% of sexually active women had used the morning-after pill, up from 4% in 2002, according to the US Centers for Disease Control and Prevention. One in four women aged 20-24 had used the drug, compared with one in nine women overall.The CDC surveyed more than 12,000 females aged 15-44 from 2006-10. The research showed that white and better educated women used the drug the most, usually due to worries that another birth control method had failed.Hispanic and black women were more likely than whites to report using the drug after unprotected sex. Regular usersOverall, about one in five women who had never been married had taken a morning-after pill, compared with just one in 20 married women.Of the women who used the pill, 59% said they had done it only once, 24% said twice, and 17% said three or more times.It was the first government report on the emergency contraceptive since regulators eased access to it seven years ago. Emergency contraception has been available by prescription in the US since 1999, before regulators approved over-the-counter sales of the drug in 2006. Also on Thursday, the CDC released a separate study on overall contraceptive use. It found that while the number of women using regular birth control pills had remained steady, the use of patches, intrauterine devices and injections had grown.BBC Newscenter_img Share Share HealthLifestyle Morning-after pill use rises in US by: – February 15, 2013last_img read more

Islanders sign Michael Dal Colle, Joshua Ho-Sang

Islanders sign Michael Dal Colle, Joshua Ho-Sang

first_imgThe New York Islanders have re-signed restricted free agents Michael Dal Colle and Joshua Ho-Sang, the team announced Monday.Dal Colle agreed to a two-year deal, while Ho-Sang signed a one-year extension. As per CapFriendly, Dal Colle’s deal carries an AAV of $700,000, while Ho-Sang will make $874,125. NHL FREE AGENCY 2019: Tracker for all 31 teams’ RFAs, UFAsBoth forwards, now 23 years old, are both Islanders 2014 first-round picks and have since remained in the organization’s farm system while other prospects — such as Mathew Barzal, who was drafted the following summer — developed more quickly.2 signings are better than 1 ✒️ 📃 The #Isles have also agreed to terms on a 2-year contract with Michael Dal [email protected] | @MDalColle71 pic.twitter.com/N0lT3Jxqqn— MSG Networks (@MSGNetworks) August 19, 2019Dal Colle made his NHL debut two seasons ago and played in 28 NHL games last season, recording three goals and four assists. He spent parts of the season in the AHL, where he scored 34 points in 34 games with the Bridgeport Sound Tigers. The two-year deal will provide him with an opportunity to further break into the lineup. Ho-Sang, meanwhile, has spent time back and forth between the Islanders’ NHL and AHL rosters over the last three seasons, and in his first year, he notched 22 points in 43 games. The Toronto native played only 10 games with the Islanders last winter before returning to Bridgeport, where he recorded 43 points in 56 games for the Sound Tigers.Questions about Ho-Sang’s character and bizarre off-ice incidents have dogged him his entire professional career, from being quickly sent back to juniors during training camp in 2015 after being late to being scratched by Bridgeport in January.Despite his professional struggles, he’s still considered a highly-talented offensive prospect. It seems a one-year contract with the Islanders will afford him one more opportunity to stick around in the NHL.last_img read more