Di seguito gli interventi pubblicati in questa sezione, in ordine cronologico.
It is already used in Swiss elections to ensure that electronic vote data is securely transmitted to central locations. And as far as we know, no current quantum cryptographic system has been compromised in the field. This may be due to the work of security researchers who spend all their waking moments—and quite a lot of their non-waking moments—trying to pick the lock on quantum systems.
Their general approach can be summed up as follows: if you can fool a detector into thinking a classical light pulse is actually a quantum light pulse, then you might just be able to defeat a quantum cryptographic system. But even then the attack should fail, because quantum entangled states have statistics that cannot be achieved with classical light sources—by comparing statistics, you could unmask the deception. In the latest of a series of papers devoted to this topic, a group of researchers has now shown that the statistics can also be faked.
Quantum cryptography relies on the concept of entanglement. With entanglement, some statistical correlations are measured to be larger than those found in experiments based purely on classical physics. Cryptographic security works by using the correlations between entangled photons pairs to generate a common secret key. If an eavesdropper intercepts the quantum part of the signal, the statistics change, revealing the presence of an interloper.
But there's a catch here. I can make a classical signal that is perfectly correlated to any signal at all, provided I have time to measure said signal and replicate it appropriately. In other words, these statistical arguments only apply when there is no causal connection between the two measurements.
You might think that this makes intercepting the quantum goodness of a cryptographic system easy. But you would be wrong. When Eve intercepts the photons from the transmitting station run by Alice, she also destroys the photons. And even though she gets a result from her measurement, she cannot know the photons' full state. Thus, she cannot recreate, at the single photon level, a state that will ensure that Bob, at the receiving station, will observe identical measurements.
That is the theory anyway. But this is where the second loophole comes into play. We often assume that the detectors are actually detecting what we think they are detecting. In practice, there is no such thing as a single photon, single polarization detector. Instead, what we use is a filter that only allows a particular polarization of light to pass and an intensity detector to look for light. The filter doesn't care how many photons pass through, while the detector plays lots of games to try and be single photon sensitive when, ultimately, it is not.
It's this gap between theory and practice that allows a carefully manipulated classical light beam to fool a detector into reporting single photon clicks.
Since Eve has measured the polarization state of the photon, she knows what polarization state to set on her classical light pulse in order to fake Bob into recording the same measurement result. When Bob and Alice compare notes, they get the right answers and assume everything is on the up and up.
The researchers demonstrated that this attack succeeds with standard (but not commercial) quantum cryptography equipment under a range of different circumstances. In fact, they could make the setup outperform the quantum implementation for some particular settings.
The researchers also claim that this attack will be very difficult to detect, but I disagree. The attack depends on very carefully setting the power in the light beams so that only a single photodetector is triggered in Bob's apparatus. Within the detector, the light beam gets divided into two and then passed through polarization filters and detected. For a single photon beam, this doesn't matter—only one detector can click at any one time. But Eve's bright bunch of photons could set multiple detectors clicking at the same time. If you periodically remove filters, then Eve will inadvertently trigger more than a single photodiode, revealing her presence.
Source: Physical Review Letters, 2011, DOI: 10.1103/PhysRevLett.107.170404 - Ars Technica - via ZeitNews.org
Scientists are reporting development of a fast, reliable new test that could help people avoid a terrible type of food poisoning that comes from eating fish tainted with a difficult-to-detect toxin from marine algae growing in warm waters. The report appears in ACS' journal Analytical Chemistry.
Takeshi Yasumoto and colleagues explain that 20,000-60,000 people every year come down with ciguatera poisoning from eating fish tainted with a ciguatoxin -- the most common source of food poisoning from a natural toxin. Fish, such as red snapper and sea bass, get the toxin by eating smaller fish that feast on marine algae that produce the toxin in tropical and subtropical areas, such as the Gulf Coast of the U.S. There's no warning that a fish has the toxin -- it smells, looks and tastes fine. But within hours of ingesting the toxin, people with ciguatera have symptoms that often include vomiting, diarrhea, numbness or tingling in the arms and legs and muscle and joint aches. Debilitating symptoms may last for months. The current test for the toxin involved giving it to laboratory mice and watching them for symptoms. It is time-consuming, may miss the small amounts present in fish, and can't tell the difference between certain forms of the disease. That's why Yasumoto's group developed a faster, more sensitive test.
They describe development of a new test, using standard laboratory instruments, that avoids those draw backs. Yasumoto's team proved its effectiveness by identifying 16 different forms of the toxin in fish from the Pacific Ocean. Clear regional differences emerged -- for example, snappers and groupers off Okinawa shores had one type, whereas spotted knifejaw captured several miles north of Okinawa had another type. They also identified 12 types of toxin in a marine alga in French Polynesia, which could be the primary toxin source. The researchers say that the method outperforms current detection methods and in addition to helping diagnose patients, it will also help scientists study how the toxins move through the food chain from one animal to another.
Source: American Chemical Society
FOR IMMEDIATE RELEASE:
On February 6th 2012, The Zeitgeist Movement Israel will host a Global Awareness Event in Tel Aviv, Israel in the context of Human Sustainability and World Peace.
On the heels of what appears to be an accelerating intent for military intervention in Iran from the United States and it allies, along with the world's major powers rapidly increasing armament developments in the midst of growing social destabilization, resource depletion and economic breakdown, The Zeitgeist Movement, a worldwide sustainability advocacy group working without borders or countries will be conducting a conference on the increasingly important issues of global cooperation and the means to obtain peace and human prosperity for the long term.
A feature of the event will be a lecture conducted by Peter Joseph, founder of The Zeitgeist Movement, entitled "Defining Peace". This talk will examine the historical roots of war; its technical irrelevancy; the State's historical psychological coercion of mass appeal; the inherent exclusive benefits to the upper class and denigration of the lower class; the broad inefficiency of the State itself as a diversionary/business entity and its inherent conflict propensity; along with how the only way of achieving lasting human peace is through the dissolving of the Market System catalysts, the Ownership Class and the State entity itself.
This now sold out event will be streamed live online for free via Ustream:
The Zeitgeist Movement is a global sustainability activist group working to bring the world together for the common goal of species sustainability before it is too late. It is a social movement, not a political one, with over 1100 chapters across nearly all countries. Divisive notions such as nations, governments, races, political parties, religions, creeds or class are non-operational distinctions in the view of The Movement. Rather, we recognize the world as one system and the human species as a singular unit, sharing a common habitat. Our overarching intent could be summarized as “the application of the scientific method for social concern.”
To learn more about our work, please visit www.thezeitgeistmovement.com
Luc Douay, of Pierre and Marie Curie University, Paris, extracted hematopoietic stem cells from a volunteer's bone marrow, and encouraged these cells to grow into red blood cells with a cocktail of growth factors. Douay's team labeled these cultured cells for tracing, and injected 10 billion of them (equalling 2 milliliters of blood) back into the marrow donor's body.
After five days, 94 to 100 percent of the blood cells remained circulating in the body. After 26 days, 41 to 63 percent remained, which is a normal survival rate for naturally produced blood cells. The cells functioned just like normal blood cells, effectively carrying oxygen around the body. "He showed that these cells do not have two tails or three horns and survive normally in the body," said Anna Rita Migliaccio of Mount Sinai Medical Center in New York.
This is great news for international health care. "The results show promise that an unlimited blood reserve is within reach," says Douay. The world is in dire need of a blood reserve, even with the rising donor numbers in the developed world. This need is even higher in parts of the world with high HIV infection rates, which have even lower reserves of donor-worthy blood.
Other attempts to synthesize blood have focused on creating an artificial blood substitute, rather than growing natural blood with artificial means. For example, Chris Cooper of the University of Essex in Colchester, UK, is working on a hemoglobin-based blood substitute that is less toxic than the protein in its unbound state. Artificial blood substitutes present a solution for transfusions after natural disasters and in remote areas. The artificial substitutes do not require refrigeration, unlike fresh and stem cell-grown blood.
The stem cell method has its own pros, though. "The advantage of stem cell technology is that the product will much more closely resemble a red cell transfusion, alleviating some of the safety concerns that continue around the use of the current generations of artificial products," says Cooper.
While Douay's results, published in the medical journal Blood, are a major step forward, mass-produced artificial blood is still a long way away. A patient in need of a blood transfusion would require 200 times the 10 billion cells that Douay and his colleagues used in the test. Robert Lanza, one of the first people to grow red blood cells in a lab on a large scale, suggests using embryonic stem cells, which could generate 10 times the amount grown by Douay.
Source: Popular Science
The research group, led by electrical and computer engineering professor Xiuling Li, developed a technique to integrate compound semiconductor nanowires on silicon wafers, overcoming key challenges in device production. The team published its results in the journal Nano Letters.
Semiconductors in the III-V (pronounced three-five) group are promising for devices that change light to electricity and vice-versa, such as high-end solar cells or lasers. However, they don't integrate with silicon seamlessly, which is a problem since silicon is the most ubiquitous device platform. Each material has a specific distance between the atoms in the crystal, known as the lattice constant.
"The biggest challenge has been that III-V semiconductors and silicon do not have the same lattice constants," Li said. "They cannot be stacked on top of each other in a straightforward way without generating dislocations, which can be thought of as atomic scale cracks."
When the crystal lattices don't line up, there is a mismatch between the materials. Researchers usually deposit III-V materials on top of silicon wafers in a thin film that covers the wafer, but the mismatch causes strain and introduces defects, degrading the device performance.
Instead of a thin film, the Illinois team grew a densely packed array of nanowires, tiny strands of III-V semiconductor that grow up vertically from the silicon wafer.
"The nanowire geometry offers a lot more freedom from lattice-matching restrictions by dissipating the mismatch strain energy laterally through the sidewalls," Li said.
The researchers found conditions for growing nanowires of various compositions of the III-V semiconductor indium gallium arsenide. Their methodology has the advantages of using a common growth technique without the need for any special treatments or patterning on the silicon wafer or the metal catalysts that are often needed for such reactions.
The nanowire geometry provides the additional benefit of enhancing solar cell performance through greater light absorption and carrier collection efficiency. The nanowire approach also uses less material than thin films, reducing the cost.
"This work represents the first report on ternary semiconductor nanowire arrays grown on silicon substrates, that are truly epitaxial, controllable in size and doping, high aspect ratio, non-tapered, and broadly tunable in energy for practical device integration," said Li, who is affiliated with the Micro and Nanotechnology Laboratory, the Frederick Seitz Materials Research Laboratory and the Beckman Institute for Advanced Science and Technology at the U. of I.
Li believes the nanowire approach could be applied broadly to other semiconductors, enabling other applications that have been deterred by mismatch concerns. Next, Li and her group hope soon to demonstrate nanowire-based multi-junction tandem solar cells with high quality and efficiency.
The therapy is much more precise than other light-therapy methods attempted to date, and it has the potential to replace chemotherapy and radiation.
Researchers at the National Cancer Institutecoupled cancer-specific antibodies with a heat-sensitive dye that damages cells when exposed to specific wavelengths of light. The antibodies recognize proteins on the exterior of cancer cells, so they would easily and accurately seek out their quarry, leaving healthy cells alone. Once bound to the cancer, the antibodies’ piggyback heat-sensitive molecule could be activated to do its job.
Led by Hisataka Kobayashi, researchers worked with several photosensitizers (light-activated molecules) before settling on one called IR700. It activates in near-infrared light and has the added bonus of fluorescence, so the researchers could easily watch its progress. They attached it to three cancer antibodies that bind to three different proteins: HER2, which is over-expressed by some breast cancers; EGFR, which is over-expressed by some lung, pancreatic, and colon cancers; and PSMA, which is over-expressed by prostate cancers.
Working with mice that had been implanted with tumors, the researchers say the cancer cells bound to the protein antibodies, and when they were exposed to infrared light, the cells died. Even a single dose of IR light made a significant difference, as the image at the top shows. Infrared light has the added benefit of penetrating several centimeters into tissue, much deeper than other wavelengths, the researchers say.
One key thing about this therapy is its selectivity, the researchers say. While other light-therapy methods can damage healthy tissue, just like radiation and chemotherapy can, this method only targets cells that are over-expressing proteins associated with certain types of cancer.
Much more work needs to be done to verify that this can work in humans — for instance, the breast cancer protein used in this study is only present in less than half of breast cancers — but the team says their method shows promise.
Source: Popular Science
The computer controlled flashes of light to start and stop this gene expression, "learning" how to reach and maintain a set value.
The groundbreaking approach could find use in future efforts to control biological processes, such as the production of biofuel from microbes.
It appears in Nature Biotechnology.
The approach is a comparatively simple means to take control of fantastically complex biochemical processes to achieve a desired result.
"The neat thing about this is that there are many people who have tried to do things like this by, for example, coding in the cell itself a synthetic circuit, putting genes and mechanisms in the cell," said co-author John Lygeros, of the Automatic Control Laboratory at the Swiss Federal Institute of Technology (ETH) Zurich.
"That's had limited success up to now."
Prof Lygeros joined Prof Mustafa Khammash of the ETH's Biosystems Science and Engineering department and Prof Hana El-Samada's group at the University of California San Francisco to try to achieve better control.
The team started with the yeast Saccharomyces cerevisiae - a well-studied strain of yeast familiar since ancient times in brewing and baking.
A study in the same journal in 2002 found that when S. cerevisiae is exposed to light, a molecule called phytochrome within it can switch forms; red light converts it to an "active form" and a deeper red converts it back.
The activity of the phytochrome can start or stop the genetic machinery that results in the production of a given protein.
The team used this trick to ensure that when the yeast was producing that protein - corresponding to the gene being switched on - it could be tracked by using a "reporter" molecule that itself gives off light in a process called fluorescence.
In that way, the team had a full loop of control: upon shining red light in, they could track how much a population of yeast cells was expressing the gene, and apply the deeper red to curb that gene expression.
The process is not simply an on-off switch, Prof Lygeros explained.
"Experimentally, it s a fairly challenging thing to do," he told BBC News.
"The fluorescence is not the only thing - there are half a dozen chemical reactions involved in this process."
The team developed a computer model to track how long each burst of light should take to precisely maintain a given amount of gene expression, allowing it to control the light tightly in a feedback loop.
The work adds to a growing amount of scientific literature in which the delicate machinery within life can be bent to the will of experimenters.
Most recently, researchers at the University of California San Francisco showed that a substantially similar approach could direct a prescribed amount of a protein to the cell wall.
Their findings should help us better understand cell signalling - the chemical messages that cells share as they co-operate within an organism.
Such methods are helping to complement time-honoured but labour-intensive genetic trickery to accomplish similar goals, Prof Lygeros explained.
"It's quite difficult to engineer synthetic circuits that do something robustly in the cell, and the hope is that by augmenting this with external signals, you can get them to behave better," he said.
"That for example may have applications in biofuel production, or antibiotic production, where they use genetically engineered organisms to increase the yields of reactions."
Source: BBC News
Experts in gravitational waves from the School of Physics and Astronomy have secured almost 16.7 million hours worth of supercomputer time to simulate and map the most violent events in the universe since the big bang – namely, collisions of black holes.
The team will use more than 1,900 computer processors over the next year to try and solve the equations of Einstein’s general theory of relativity.
The ultimate goal of the simulations is the direct observation of black-hole collisions through the gravitational waves they emit.
"Gravitational waves are ripples in space and time – predicted by Einstein almost 100 years ago," according to Mark Hannam, School of Physics and Astronomy, who will lead the Cardiff research team.
"However, despite Einstein’s predictions – they have not yet been directly detected. Gravitational waves are generated by accelerating masses, such as orbiting black holes, similar to the way accelerating electrical charges emit electromagnetic waves, like light, infra-red and radio waves - with the important difference that gravitational waves are far weaker.
"For this reason it is electromagnetic waves that have told us everything we have learnt about the cosmos since ancient times. If we could also detect gravitational waves, that would push open a new window on the universe, and tell us about its `dark side'," he added.
Over the past decade a network of gravitational wave detectors has been built, including the US Laser Interferometer Gravitational-Wave Observatory (LIGO) and the European GEO600 and Virgo detectors, with the ambitious goal of not only making the first direct detection of the gravitational waves, but also to observe the entire Universe through gravitational radiation.
Cardiff's researchers work on theoretical modelling of black-hole-binary collisions using state-of-the-art numerical techniques and high performance computer clusters, strong field tests of gravity with gravitational-wave observations and the development of algorithms and software to search for gravitational waves.
Researchers at Cardiff play leading roles within the LIGO Scientific Collaboration, in particular in gravitational-wave searches for compact binary coalescences, supernovae, gamma-ray bursts, and other transient sources.
Coalescing black holes are prime candidates for the first observations. The results of this project will help to identify the sources of these signals, and contribute to answering important open questions in astrophysics and fundamental physics, such as whether the objects created in these cosmic collisions are really black holes, or even more exotic objects like naked singularities.
In the process the team hope to be able to test if Einstein's theory of gravity is correct, or whether, just as Newton's gravity gave way to Einstein's, perhaps Einstein's relativity gives way to even deeper insights into the nature of space and time.
The research team comprises more than 20 physicists working at Cardiff, the Universities of Jena, Vienna, and the Balearic Islands, the Albert Einstein Institute in Potsdam, and the California Institute of Technology. Solving Einstein's equations on supercomputers to accurately describe black holes became possible only after a series of breakthroughs in 2005, and the mostly young researchers are excited to be part of a scientific revolution.
"The detectors are pushing against the limits of current technology, and now we will help them with simulations that are at the cutting edge of computing power. Access to such vast computing resources is a fantastic boost for scientific research in Wales," Dr. Hannam added.
While supercomputing resources in Europe used to be relatively scarce, the PRACE Research Infrastructure now provides access to world-class supercomputers for European research projects, which undergo a competitive peer review process.
The PRACE infrastructure currently consists of three world-class supercomputers, which can each perform about 1 Petaflop which is a thousand billion arithmetic operations per second. The first machine in the network, the German Jugene, started operation in 2010, and it was joined in early 2011 by the French machine Curie, and the German system Hermit is about to officially start operation on November 1.
Future computers in the PRACE network are planned in Germany, Italy, and Spain.
Source: Cardiff University
The company's most recent launch includes new solar chargers that can power up your laptop while latched on to a durable backpack.
The new Array backpack pairs up with the Fuse 10W. The Fuse 10W is a detachable solar cell that can be attached to other packs or bike racks. But the Array is a great option for anyone from a student who needs extra battery power to hikers and campers who are off-grid.
According to Voltaic, the Fuse 10W provides as much as 30 minutes of laptop run-time for every hour in the sunlight. The charger will also work for tablet devices, digital cameras and other handheld devices. The holy grail for solar chargers is one powerful enough to run a laptop. While we don't have anything that can be basically plugged in and keep a laptop running all day long, this one sounds like a really solid option.
It's not exactly a cheap option though -- you pay for quality. The Fuse 10W is $339, and the Array backpack with the charger is $389. While it sounds expensive, this is actually competitive pricing for high end solar-powered backpacks. And the solar cell on the Array can be removed and attached elsewhere just like the Fuse 10W.
“Since we launched the first solar backpack in 2004, the number one customer request has been to make a backpack that charges laptops,” said Shayne McQuade, CEO of Voltaic Systems. “With the Array and Fuse 10W, we are giving our customers two great portable charging options.”
The battery included with the Fuse 10W has 60 watt hours of capacity, and the backpack can fit a laptop along with other items. And of course, as with other Voltaic packs, the fabric is made from 100% recycled PET.
Instead, the team has developed a way to improve air filter technology to specifically target influenza viruses, effectively stopping them beforethey get inside our bodies and make us ill. The nice thing about air filters is that they work both ways, so sick individuals wearing the modified filters will end up shedding less viruses into the environment too, which can also help reduce the rate of new infections.
In their study recently published online in the journal, Biomacromolecules, researchers Xuebing Li, Peixing Wu et al, point out that worldwide every year, on average, nearly 300,000 succumb to flu viruses. Millions more are sickened, which, aside from the suffering, translates into substantial economic losses.
Antibiotics don't work on viruses and so don't enter the equation, but there are numerous anti-viral drugs (amantadine, oseltamivir, rimantidine and zanamivir, to name a few) which, while initially effective, are beginning to lose some of their clout. It doesn't help that the little buggers are constantly mutating into new strains either, meaning pharmaceuticals and vaccines are always playing catch-up.
Since viruses can only replicate inside of living host cells, Li and his group reasoned that a new approach was needed to help stop these deadly pathogens from multiplying and hit upon an adaptation of the very mechanism viruses use to infect cells.When a virus targets a host cell, a protein which peppers its outer surface, hemagglutinin (HA), seeks out and binds to multiple sugars or glycans (the bound monosaccharides sialic acid and lactose- SL) on the host's membrane surface. The researchers found that the versatile linear polysaccharide, chitosan, made from the chitin found in crab and shrimp shells, was an ideal substance to bind SL to otherwise pristine filter fibers. As the diagram below shows, viruses now have to run a gauntlet of fibers festooned with the very substance they're attracted to, effectively stopping them in their tracks. That's news that should help all of us breathe just a little bit easier.