Tag: 上海仙霞路夜生活

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The Warriors need more of this Kevon Looney going forward

first_imgClick here if you’re unable to view the gallery on your mobile device.OAKLAND — DeMarcus Cousins crumbled in front of the Warriors bench just three and a half minutes into Game 2, clutching his left quad and wincing in pain.Kevon Looney watched from his seat, eerily familiar with what Cousins had just endured. After Cousins clawed back from ACL surgery this year only to suffer a likely season-ending torn quad early in the first quarter Monday night, his role will be filled in large part by …last_img read more

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Botulinum Toxin Deactivated by One Slight Change

first_imgA researcher at Brookhaven National Laboratory mutated a botulinum enzyme by just one amino acid, and abolished its toxicity.  The mutation, a change from a glutamate to a glutamine at one position, increased the distance from a zinc atom to a water molecule by 0.6 angstrom, less than one tenth of a billionth of a meter.  This was enough to prevent the botulinum enzyme from cleaving its target protein, a neurotransmitter.  The modified enzyme could still bind to it, but not cleave it.This experiment points out the specificity of enzymes.  We are led to believe that evolution works by mutating things recklessly, but look how slight a change totally disarmed this enzyme.  A second observation is that toxins like botulinum might have originally had a beneficial function, but became toxic through degenerative mutations.  Though difficult to prove, it is an interesting suggestion that, just as with mentally ill humans, it doesn’t take much to turn a benign individual into a killer.  That isn’t evolution.  It’s a breakdown in quality control.  Another possibility is that botulinum’s function, cleaving a neurotransmitter, was originally beneficial.  As reported before, many deadly poisons actually follow a “hormesis” curve and only become harmful above certain levels (see 02/12/2003 headline).  Botox is now all the rage.  In minute amounts, it is proving versatile for everything from beauty treatments to tumor reduction; see for instance this report on EurekAlert about University of Pittsburgh scientists using to ease symptoms of enlarged prostate.(Visited 14 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more

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Mercury Orbital Science Begins

first_img This is a historic year for exploration of Mercury.  The three prior flybys already tantalized planetary scientists, but now floods of images and data can be expected for three years.  It’s been a long time since Mariner 10 visited in 1971 with a few brief passes.  Readers should applaud the designers and operators of this successful spacecraft. Note the difference between the discovery and explanation phases of science.  Discovery does not always follow a method.  Discoveries can come by mistake, by accident, by a dream, a hunch, tacit knowledge, abductive reasoning, or planning new ways to get closer to a target of investigation.  The latter might include a ladder, climbing a higher peak, venturing farther into inhospitable environments, or sending better robotic observers where human senses cannot go, as in planetary exploration. Explaining the observations is a different matter entirely.  Observations may suggest explanations, may falsify or confirm predictions, but do not explain themselves in a vacuum.  Remember to keep discovery and explanation distinct when reading articles such as these.  Scientists and their reporters often mix them together, giving the impression there is only one explanation.  That may be the case, but must be demonstrated, not assumed. Often the surprises and anomalies are the most interesting parts of the story.(Visited 16 times, 1 visits today)FacebookTwitterPinterestSave分享0 Now that the MESSENGER spacecraft has settled into its orbit, systematic detailed observations are coming in.  The Carnegie Institution has posted preliminary findings from the orbital science tour, rejoicing that “Tens of thousands of images reveal major features on the planet in high resolution for the first time,” and confessing that the data are confirming some predictions and revealing surprises.  Among the surprises, “Mercury’s surface composition differs from that expected for the innermost of the terrestrial planets, and Mercury’s magnetic field has a north-south asymmetry that affects interaction of the planet’s surface with charged particles from the solar wind.”  Embedded in the review are links to instrument descriptions at the MESSENGER website, where photos and presentations from a press conference have been posted. The mission is managed by the Applied Physics Lab at Johns Hopkins University. Update 06/20/2011: Live Science posted a list of “The Greatest Mysteries of Mercury.”  It concerns the planet’s density, magnetic field, and atmosphere.last_img read more

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