Making homemade guns on a 3-D printer becomes so real that experts suggests stronger laws on gunpowder Reply

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With controversy swirling over gun-sale background checks, limiting the size of weapon magazines and retaining Second Amendment rights, the problem of making homemade guns with 3-D printers has become a matter of public concern. 

 Laws mean little if a determined criminal or a hobbyist teen wants to make plastic guns or extra-high capacity magazines, says Hod Lipson, Cornell University professor of engineering and a pioneer in 3-D printing. 

“With a homemade 3-D printer, you can print a gun using ABS plastic, the same material that LEGOS are made out of. You can even use nylon, and that’s pretty tough,” he says. “You won’t be able to make a sniper rifle with a 3-D printer and it won’t shoot 10 rounds a second, but the gun you can make could be dangerous. And a high-capacity magazine is nothing more than a strong plastic box with a spring. It’s trivial to print.”

 

Lipson and co-author Melba Kurman just published a new book, “Fabricated: The promise and peril of a machine that can make (almost) anything.” (Wiley, 2013.) The book includes a chapter on “3-D printing and the law,” which addresses the legal and ethical challenges raised by 3-D printed firearms. The book also explores 3-D printing’s impact on consumer safety, intellectual property, and ethics.

 

As Lipson and Kurman detail, three-dimensional printers are intended to do the world good. In industry, 3-D printers can make hard-to-find spare parts and complex new devices. Researchers are developing techniques to 3-D print tailored and personalized body parts like he

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MIT: A Cheap and Easy Plan to Stop Global Warming Reply

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Here is the plan. Customize several Gulfstream business jets with military engines and with equipment to produce and disperse fine droplets of sulfuric acid. Fly the jets up around 20 kilometers—significantly higher than the cruising altitude for a commercial jetliner but still well within their range. At that altitude in the tropics, the aircraft are in the lower stratosphere. The planes spray the sulfuric acid, carefully controlling the rate of its release. The sulfur combines with water vapor to form sulfate aerosols, fine particles less than a micrometer in diameter. These get swept upward by natural wind patterns and are dispersed over the globe, including the poles. Once spread across the stratosphere, the aerosols will reflect about 1 percent of the sunlight hitting Earth back into space. Increasing what scientists call the planet’s albedo, or reflective power, will partially offset the warming effects caused by rising levels of greenhouse gases.

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Birds’ UV Vision has arisen independently more than 14 times during evolution Reply

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Birds depend on their color vision for selecting mates, hunting or foraging for food, and spotting predators. Until recently, ultraviolet vision was thought to have arisen as a one-time development in birds. But a new DNA analysis of 40 bird species shows the shift between violet (shorter wavelengths on the electromagnetic spectrum) and ultraviolet vision has occurred at least 14 times.

 

“Birds see color in a different way from humans,” study co-author Anders Ödeen, an animal ecologist at Uppsala University in Sweden, told LiveScience. Human eyes have three different color receptors, or cones, that are sensitive to light of different wavelengths and mix together to reveal all the colors we see. Birds, by contrast, have four cones, so “they see potentially more colors than humans do,” Ödeen said.

 

Birds themselves are split into two groups based on the color of light (wavelength) that their cones detect most acutely. Scientists define them as violet-sensitive or ultraviolet-sensitive, and the two groups don’t overlap, according to Ödeen. Birds of each group would see the same objects as different hues.

 

The study researchers sequenced the DNA from the 40 species of birds, from the cockatiel to the whitebearded manakin. They extracted DNA from the bases of feather quills, blood, muscle or other tissue. From that DNA, the scientists reconstructed the proteins that make up the light-sensitive pigments in the birds’ eyes. Differences in the DNA revealed which birds were sensitive to violet light versus ultraviolet.

 

“That change is very simple, apparently,” Ödeen said. “It just takes a single mutation” in the DNA sequence. While that change may seem insignificant, it can be compared to the difference humans see between red and green. Why the bird lineages switched their color sensitivity — essentially species of a certain branch on the family tree evolved to have the reverse type of vision — is still something of a mystery. The ability to attract mates while still evading predators could be one reason. Ultraviolet light might also provide higher contrast that makes finding food easier. Other factors are environmental — open spaces have more UV light than do forests, for example. Ultimately, the color sensitivity may be a result of other changes that affect the amount of ultraviolet light the birds’ eyes receive.

mdashf‘s insight:

the suckers are real dreamers and visionaries 

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Protein ‘filmed’ while unfolding at atomic resolution Reply

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When proteins get “out of shape”, the consequences can be fatal. They lose their function and in some cases form insoluble, toxic clumps that damage other cells and can cause severe diseases such as Alzheimer’s or Parkinson’s. Researchers at the Max Planck Institute for Biophysical Chemistry and the German Center for Neurodegenerative Diseases in Göttingen – in collaboration with Polish colleagues – have now “filmed” how a protein gradually unfolds for the first time. By combining low temperatures and NMR spectroscopy, the scientists visualized seven intermediate forms of the CylR2 protein while cooling it down from 25°C to – 16°C. Their results show that the most instable intermediate form plays a key role in protein folding. The scientists’ findings may contribute to a better understanding of how proteins adopt their structure and misfold during illness.

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An amazing invisible truth about Wikipedia hiding inside Wikipedia’s GeoTag Information Reply

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A large number of Wikipedia articles are geocoded. This means that when an article pertains to a location, its latitude and longitude are linked to the article. As you can imagine, this can be useful to generate insightful and eye-catching infographics.

 

A while ago, a team at Oxford built this magnificent tool to illustrate the language boundaries in Wikipedia articles. This led me to wonder if it would be possible to extract the different topics in Wikipedia.

 

This is exactly what I managed to do in the past few days. I downloaded all of Wikipedia, extracted 300 different topics using a powerful clustering algorithm, projected all the geocoded articles on a map and highlighted the different clusters (or topics) in red. The results were much more interesting than I thought. For example, the map on the left shows all the articles related to mountains, peaks, summits, etc. in red on a blue base map.  The highlighted articles from this topic match the main mountain ranges exactly.

 

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Virtual quantum particles can have real physical effects: A vacuum can yield flashes of light Reply

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A vacuum might seem like empty space, but scientists have discovered a new way to seemingly get something from that nothingness, such as light. And the finding could ultimately help scientists build incredibly powerful quantum computers or shed light on the earliest moments in the universe’s history.

 

Quantum physics explains that there are limits to how precisely one can know the properties of the most basic units of matter—for instance, one can never absolutely know a particle’s position and momentum at the same time. One bizarre consequence of this uncertainty is that a vacuum is never completely empty, but instead buzzes with so-called “virtual particles” that constantly wink into and out of existence.

 

These virtual particles often appear in pairs that near-instantaneously cancel themselves out. Still, before they vanish, they can have very real effects on their surroundings. For instance, photons—packets of light—can pop in and out of a vacuum. When two mirrors are placed facing each other in a vacuum, more virtual photons can exist around the outside of the mirrors than between them, generating a seemingly mysterious force that pushes the mirrors together.

 

This phenomenon, predicted in 1948 by the Dutch physicist Hendrick Casimir and known as the Casimir effect, was first seen with mirrors held still . Researchers also predicted a dynamical Casimir effect that can result when mirrors are moved, or objects otherwise undergo change. Now quantum physicist Pasi Lähteenmäki at Aalto University in Finland and his colleagues reveal that by varying the speed at which light can travel, they can make light appear from nothing.

 

The speed of light in a vacuum is constant, according to Einstein’s theory of relativity, but its speed passing through any given material depends on a property of that substance known as its index of refraction. By varying a material’s index of refraction, researchers can influence the speed at which both real and virtual photons travel within it. Lähteenmäki says one can think of this system as being much like a mirror, and if its thickness changes fast enough, virtual photons reflecting off it can receive enough energy from the bounce to turn into real photons. “Imagine you stay in a very dark room and suddenly the index of refraction of light [of the room] changes,” Lähteenmäki says. “The room will start to glow.”

 

The researchers began with an array of 250 superconducting quantum-interference devices, or SQUIDs—circuits that are extraordinarily sensitive to magnetic fields. They inserted the array inside a refrigerator. By carefully exerting magnetic fields on this array, they could vary the speed at which microwave photons traveled through it by a few percent. The researchers then cooled this array to 50 thousandths of a degree Celsius above absolute zero. Because this environment is supercold, it should not emit any radiation, essentially behaving as a vacuum. “We were simply studying these circuits for the purpose of developing an amplifier, which we did,” says researcher Sorin Paraoanu, a theoretical physicist at Aalto University. “But then we asked ourselves—what if there is no signal to amplify? What happens if the vacuum is the signal?”

 

The investigators caution that such experiments do not constitute a magical way to get more energy out of a system than what is input. For instance, it takes energy to change a material’s index of refraction.

Instead, such research could help scientists learn more about the mysteries of quantum entanglement, which lies at the heart of quantum computers—advanced machines that could in principle run more calculations in an instant than there are atoms in the universe. The entangled microwave photons the experimental array generated “can be used for a form of quantum computation known as ‘continuous variable’ quantum information processing,” Girvin says. “This is a direction which is just beginning to open up.” Wilson adds that these systems “might be used to simulate some interesting scenarios. For instance, there are predictions that during cosmic inflation in the early universe, the boundaries of the universe were expanding nearly at light-speed or faster than the speed of light. We might predict there’d be some dynamical Casimir radiation produced then, and we can try and do tabletop simulations of this.”

So the static Casimir effect involves mirrors held still; the dynamical Casimir effect can for instance involve mirrors that move.

 

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