Robot legs walk like John Travolta

post from Top stories on 05 July 2012 09:56:32 PM. © Top stories

A group of US researchers has produced a robotic set of legs which they believe is the first to fully model walking in a biologically accurate manner.

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http://machineslikeus.com/news/robot-legs-walk-john-travolta

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First photo of shadow of single atom

post from Top stories on 05 July 2012 09:48:50 PM. © Top stories

Story Source

In an international scientific breakthrough, a Griffith University research team has been able to photograph the shadow of a single atom for the first time.

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http://machineslikeus.com/news/first-photo-shadow-single-atom

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Antibodies reverse type 1 diabetes

post from Top stories on 05 July 2012 09:41:40 PM. © Top stories

Story Source

Scientists at the University of North Carolina School of Medicine have used injections of antibodies to rapidly reverse the onset of Type I diabetes in mice genetically bred to develop the disease.

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http://machineslikeus.com/news/antibodies-reverse-type-1-diabetes

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Dust mysteriously vanishes from around nearby
star

post from Top stories on 05 July 2012 09:37:59 PM. © Top stories

Story Source

Astronomers report a baffling discovery never seen before: An extraordinary amount of dust around a nearby star has mysteriously disappeared.

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http://machineslikeus.com/news/dust-mysteriously-vanishes-around-nearby-star

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Image of the Week: Has the Elusive Higgs Boson
been Found

post from Visionlearning blog on 05 July 2012 08:39:00 PM. © Visionlearning blog

Unless you were hiding under a rock this week, you likely heard the buzz about the Higgs boson (or perhaps more accurately the "Higgs-like particle"). The sub-atomic particle, proposed in 1964 by Peter Higgs and other theorists, has eluded scientist for decades. But on Wednesday July 4th, scientists announced that they had amassed enough evidence to officially describe a new sub-atomic particle--one with characteristics closely matched to the long-sought-after Higgs boson.

Image © 2012 CERNFor two years, physicists working at the Large Hadron Collider (LHC) near Geneva, Switzerland have been smashing protons together at high speeds and observing the crash sites with sensitive detectors. They were looking for signs that the collisions had (at least occasionally) emitted a Higgs boson, which according to its theoretical properties would immediately decay into other particles. Our image of the week is a computer rendering of one of the experimental collisions. The yellow dotted lines and green towers radiating out from the crash show characteristics matching what scientists would expect to observe as a Higgs boson decayed into a pair of photons.

By examining the subatomic shrapnel from trillions of collisions, the scientists were able to conclude that they had indeed shaken loose this new Higgs-like particle. This is big news because the Higgs boson is the last piece "missing" (undetected by science) from the "Standard Model" of particle physics that describes the structure of matter and our universe.

While the researchers are cautious about saying that the particle they have observed is definitely the Higgs boson, they are certain that it's a huge discovery for physics. And the possibility that it's a different, as-yet-unpredicted particle is equally as exciting. To gain a clearer picture of the discovery, the research teams will gather as much data as possible before the LHC shuts down for a two-year period of maintenance and upgrades.

Bonus footage! We selected an image of the week, but we couldn't resist sharing this video as well. NOVA produced it last year when scientists were still searching for evidence of the Higgs boson. It's a little dated in that respect, but it gives a nice, quick explanation of the Higgs boson and an interview with Peter Higgs.

Watch The Higgs Particle Matters on PBS. See more from NOVA.
Dig Deeper
Learn more about the LCH, the massive (27-kilometer-long) particle accelerator, where scientists labored to find evidence of the Higgs boson

Read the Science News story "Higgs Found" by Alexandra Witze

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http://feedproxy.google.com/~r/VisionlearningBlog/~3/NLBvqVC6jHk/image-of-week-ha
s-elusive-higgs-boson.html

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Shedding Light on the Scarred Face of Asteroid
Vesta

post from Blog - NASA Jet Propulsion Laboratory on 05 July 2012 06:22:56 PM. © Blog - NASA Jet Propulsion Laboratory

By Marc RaymanAs NASA’s Dawn spacecraft investigates its first target, the giant asteroid Vesta, Marc Rayman, Dawn’s chief engineer, shares a monthly update on the mission’s progress.This image, from NASA’s Dawn spacecraft, shows rock material that has moved across the surface and flowed into a low area in the ridged floor of the Rheasilvia basin [...]

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http://blogs.jpl.nasa.gov/2012/07/shedding-light-on-the-scarred-face-of-asteroid-
vesta/

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Caption This for 07/06/12

post from CR4 - Recent Blog Entries on 05 July 2012 05:45:00 PM. © CR4 - Recent Blog Entries

This week's image:Be sure to vote for your favorite caption!

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http://cr4.globalspec.com/blogentry/20431/Caption-This-for-07-06-12?from_rss=1

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Mars Exploration Rovers Update: Opportunity Digs
Cape York, Roves to New Milestone

Even robots deserve a break once in a while, and when the Mars Odyssey orbiter went into safe mode in June, Opportunity got the chance to hang out and leisurely take in her surroundings at the Red Planet, while the Mars Exploration Rover (MER) mission downshifted into lower gear.

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http://www.planetary.org/blogs/guest-blogs/a-j-s-rayl/2012-06-mer-update-opportun
ity-digs-cape-york-roves-to-new-milestone.html

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Does 5-sigma = discovery

Yesterday, CERN scientists announced that they had "clear signs of a new particle," after a lengthy search for confirmation of the Higgs boson. Although scientists don't know how all of the properties of this new particle will match up with theoretical predictions, everyone's excited about this discovery.

Researchers from both experiments emphasized that these were "5-sigma signals," at 125 and 126 GeV for the independent CMS and ATLAS experiments, respectively. But what does a 5-sigma result mean, and why do particle physicists use this as a benchmark for discoveries?
To answer these questions, we'll have to look at one of the statistician's oldest friends and C-student's worst enemies: the normal distribution or bell curve.

The normal distribution is the most familiar class of statistical distributions, and it consistently rears its head in a number of sciences including physics. When scientists announce 3-sigma (or 4-sigma or 5-sigma) results, they're talking about standard deviations from an expected value.

As you can see in the graph above, the normal distribution takes the shape of a bell that quickly tapers off. The curve has a mean (or average) value at the center, and as you move from away from the curve, the likelihood of seeing these outer values decreases. The standard deviation is a way of measuring this likelihood.

There's an approximately 68 percent chance that a value will fall within the first standard deviation of the distribution ? or 1-sigma; the darkest shaded blue section in the graph above represents this first range. Here's the corresponding approximate percentages for the next sigmas:

2-sigma: 95.5 percent

3-sigma: 99.73 percent

4-sigma: 99.993 percent

5-sigma: 99.99994 percent

So that means that purely statistical fluctuations will give you a result way out in the 5-sigma range 0.00006 percent of the time.

When physicists announce that they have a 5-sigma result, that means that there's a 1 in 3.5 million chance that it was the result of a statistical fluctuation over the spectrum of experiments they performed. Particle physicists working on the CMS and ATLAS experiments are looking for "bumps" in their data that stand out from the background. When these bumps reach the 5-sigma level, they have very good reason to believe that they've discovered or observed a new particle.

In fact, physicists have relied on this benchmark for years to assign varying degrees of confidence to their results. For publication in Physical Review Letters, for instance, 5-sigma results are generally called "observations" or "discoveries," according to Jack Sandweiss, an editor of the journal and physicist at Yale University.

Sandweiss added that 3-sigma results usually warrant calling the result "evidence" of a new particle, but scientists need more statistical certainty to include terms like "discovery" in a technical paper. Previously, scientists may have placed more weight in 3-sigma results, but many promising 3-sigma results have turned out to be nothing more than statistical fluctuations. When more data was eventually collected, many 3-sigma have disappeared into the background.

So does this mean that the 5-sigma Higgs-like particle results mean that scientists are 99.99994 percent sure that they've found the Higgs boson? Not exactly.

More than Sigmas

Although statistical significance can be a good guideline for many physics experiments, scientists can't base their results solely on these benchmarks. In fact, other errors can creep into the data and contaminate entire datasets, even very promising ones.

Remember when neutrinos were supposedly traveling faster than light late last year? That result reached a six-sigma level of confidence ? even higher than the 5-sigma level convention required for new particle discoveries. But we learned earlier this year that neutrinos indeed obey the universal speed limit, so what went wrong?

Most crucially, the faster-than-light neutrino experiment suffered from a systematic error that affected all of the data they took; faulty cables consistently gave them bad readings. No matter how many times researchers repeated the experiments, they would get the same yet inaccurate results.

This situation is akin to measuring someone's height with a meter stick that is several inches longer than it should be. Even if you take hundreds of measurements and average all of the tiny human errors and approximations, you'll never avoid the fact that your meter stick is giving you consistently bad results.

So how do scientists make sure they avoid this problem when statistical analyses can't account for it? Part of the answer is using independent experiments, like CMS and ATLAS, because systematic errors are less likely to affect experiments with different designs.

This is part of the reason why scientists are so excited about the recent results. Scientists are seeing not only very high sigma bumps in the data but also similar bumps from two independent experiments.

For now, plenty of evidence has piled up to support the discovery of a Higgs-like particle. Now scientists have to look at the data more closely to uncover this new particle's properties. Maybe they'll find something entirely unexpected.

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If you want to keep up with Hyperspace, AKA Brian, you can follow him on Twitter.

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http://feedproxy.google.com/~r/physicscentral/PhysicsBuzz/~3/00gwND13yJA/does-5-s
igma-discovery.html

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Birth of a New Moon

As astronaut Don Pettit prepared for his return to Earth, he tweeted several beautiful shots from the Space Station.

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http://www.planetary.org/blogs/emily-lakdawalla/2012/07041200-birth-of-a-new-moon
.html

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