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Walid Damouny

What scientists know about jewel beetle shimmer - 0 views

www.physorg.com/news167585862.html

PhysOrg.com beetles insects pigment polymer colour light optics imaging

shared by Walid Damouny on 24 Jul 09 - Cached
  • Walid Damouny on 24 Jul 09
     
    "Jewel beetles" are widely known for their glossy external skeletons that appear to change colors as the angle of view changes. Now they may be known for something else--providing a blueprint for materials that reflect light rather than absorbing it to produce colors.
thinkahol *

Graphene may reveal the grain of space-time - physics-math - 13 May 2011 - New Scientist - 1 views

www.newscientist.com/...al-the-grain-of-spacetime.html

Graphene reveal the grain of space-time - physics-math 13 May 2011 New Scientist

shared by thinkahol * on 16 May 11 - No Cached
  • thinkahol * on 16 May 11
     
    COULD the structure of space and time be sketched out inside a cousin of plain old pencil lead? The atomic grid of graphene may mimic a lattice underlying reality, two physicists have claimed, an idea that could explain the curious spin of the electron. Graphene is an atom-thick layer of carbon in a hexagonal formation. Depending on its position in this grid, an electron can adopt either of two quantum states - a property called pseudospin which is mathematically akin to the intrinsic spin of an electron. Most physicists do not think it is true spin, but Chris Regan at the University of California, Los Angeles, disagrees. He cites work with carbon nanotubes (rolled up sheets of graphene) in the late 1990s, in which electrons were found to be reluctant to bounce back off these obstacles. Regan and his colleague Matthew Mecklenburg say this can be explained if a tricky change in spin is required to reverse direction. Their quantum model of graphene backs that up. The spin arises from the way electrons hop between atoms in graphene's lattice, says Regan. So how about the electron's intrinsic spin? It cannot be a rotation in the ordinary sense, as electrons are point particles with no radius and no innards. Instead, like pseudospin, it might come from a lattice pattern in space-time itself, says Regan. This echoes some attempts to unify quantum mechanics with gravity in which space-time is built out of tiny pieces or fundamental networks (Physical Review Letters, vol 106, p 116803). Sergei Sharapov of the National Academy of Sciences of Ukraine in Kiev says that the work provides an interesting angle on how electrons and other particles acquire spin, but he is doubtful how far the analogy can be pushed. Regan admits that moving from the flatland world of graphene to higher-dimensional space is tricky. "It will be interesting to see if there are other lattices that give emergent spin," he says.
Janos Haits

GeoGebra - 0 views

www.geogebra.org

math GeoGebra Geometry measurement elementary_math Angle Triangle education science middle-level

shared by Janos Haits on 14 Aug 16 - Cached
  • Janos Haits on 14 Aug 16
     
    "THE GRAPHING CALCULATOR FOR FUNCTIONS, GEOMETRY, ALGEBRA, CALCULUS, STATISTICS AND 3D MATH!"
Skeptical Debunker

Controversial Studies Trigger Dropoff in Osteoporosis Treatment - 0 views

www.physorg.com/news186087673.html

treatment osteoporosis kyphoplasty study flaws

shared by Skeptical Debunker on 23 Feb 10 - Cached
  • The North American Spine Society and the Society of Interventional Radiology have pointed to flaws in both studies. And earlier studies, published over 15 years, found major benefits to kyphoplasty and a related procedure called vertebroplasty. "We're missing opportunities for patients to receive a safe and effective treatment that can significantly reduce their pain and disability," said Malamis, an interventional radiologist. The procedures are used to treat vertebral compression fractures in patients with osteoporosis and other conditions that result in brittle bones. In a vertebroplasty, an acrylic cement is injected into a fractured vertebra. In a kyphoplasty, a balloon-tipped catheter first is inserted into the fracture. The balloon is inflated to restore the height and shape of the vertebra before the cement is injected. Neva Nelson, 74, of Naperville, Ill., said a kyphoplasty that Malamis performed in October, 2009, has greatly reduced her pain in a vertebra in her lower back that she fractured after falling on ice. Before her kyphoplasty, Nelson had to sit on cushions. Walking, and especially standing, were painful. "I had to do something," she said. "I could not go on like that." Nelson said that since undergoing her kyphoplasty, "I don't have to worry about my back any more." In the controversial studies, patients were randomly assigned to receive a vertebroplasty or a placebo-like "sham" procedure. In the sham procedure, patients received an injection of anesthetic, but no cement. However, patients in severe pain are reluctant to enroll in a trial where there's a 50 percent chance of receiving a sham treatment. In one of the studies, researchers had to screen 1,813 patients to enroll just 131 subjects. In the other study, only 78 of 219 eligible patients were enrolled. This low enrollment rate raises the possibility that the patients who did enroll were not representative. Patients experience the greatest pain during the first three months after a compression fracture. Thereafter, pain gradually subsides. Thus, a vertebroplasty or kyphoplasty provides the greatest benefit when performed within a week or two of the fracture. But the studies enrolled patients up to 12 months after fractures. In addition to reducing pain and disability, a kyphoplasty can reduce the risk of subsequent fractures by improving the angle and height of the spine. The studies evaluated vertebroplasty alone, and did not include the more innovative and very different kyphoplasty procedure. Malamis suggests the medical community wait for the results of additional studies now underway before passing final judgment on vertebroplasty or kyphoplasty. In the mean time, he notes that Medicare still covers the procedures.
  • Skeptical Debunker on 23 Feb 10
     
    Dr. Angelo Malamis says that 90 percent of his patients who have undergone a treatment called balloon kyphoplasty for vertebral fractures report significant reductions in pain and disability. But the number of kyphoplasty referrals Malamis has received from primary care doctors has dropped sharply since two controversial studies were published last year in the New England Journal of Medicine. In findings that have been disputed by two medical societies, researchers reported that a procedure related to kyphoplasty was not significantly better than a placebo-like procedure in reducing pain and disability.
ariful10

How Does A Turbine Work? - 0 views

www.prettysmile.xyz/turbine-work

Turbine science education water turbines steam Gas

shared by ariful10 on 24 Jul 17 - No Cached
  • ariful10 on 24 Jul 17
     
    A turbine is a machine used to convert energy generated by moving liquid, gas or air into work. For example, the energy produced by fast flowing water is made to spin a rotating shaft by pushing on the angled blades set around a wheel mounted on the shaft, and this action produces the required work. ...
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