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Self-propelled subatomic particles accelerate without a push, extending lifetime of unstable isotopes

Self-propelled subatomic particles accelerate without a push, extending lifetime of unstable isotopes | Physics | Scoop.it

Some physical principles have been considered immutable since the time of Isaac Newton: Light always travels in straight lines. No physical object can change its speed unless some outside force acts on it.

 

Not so fast, says a new generation of physicists: While the underlying physical laws haven’t changed, new ways of “tricking” those laws to permit seemingly impossible actions have begun to appear. For example, work that began in 2007 proved that under special conditions, light could be made to move along a curved trajectory — a finding that is already beginning to find some practical applications.

 

Now, in a new variation on the methods used to bend light, physicists at MIT and Israel’s Technion have found that subatomic particles can be induced to speed up all by themselves, almost to the speed of light, without the application of any external forces. The same underlying principle could also be used to extend the lifetime of some unstable isotopes, perhaps opening up new avenues of research in basic particle physics.

 

The findings, based on a theoretical analysis, were published in the journal Nature Physics by MIT postdoc Ido Kaminer and four colleagues at the Technion. The new findings are based on a novel set of solutions for a set of basic quantum-physics principles called the Dirac equations; these describe the relativistic behavior of fundamental particles, such as electrons, in terms of a wave structure. (In quantum mechanics, waves and particles are considered to be two aspects of the same physical phenomena). By manipulating the wave structure, the team found, it should be possible to cause electrons to behave in unusual and counterintuitive ways.


Via Dr. Stefan Gruenwald
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A fuel cell for home? A miniature power station for home use is based on a solid fuel cell

A fuel cell for home? A miniature power station for home use is based on a solid fuel cell | Physics | Scoop.it
It converts chemical energy directly into electrical energy. Still, there hadn’t been a market breakthrough for the fuel cell. The systems were too complex. Now, Fraunhofer and Vaillant have developed a simple device for home use.

 

Together with the heater manufacturer Vaillant, the IKTS has developed a compact, safe and sturdy fuel cell system that generates electricity and heat in private households from natural gas. The researchers were particularly responsible for the construction of the prototype, the design of the overall system, the design of the ceramic components and the development of the reformer and the afterburner. The devices are currently being tested in private households in the Callux practice test (www.callux.net). 

They are as compact as classical gas heaters that only produce heat. Moreover, they can comfortably be mounted on the wall and easily be maintained. With an output of one kilowatt, they cover the average current consumption for a four-person household. The Federal Ministry of Transport and digital infrastructure BMVI is promoting Callux. Currently, in the European demonstration project ene.field (www.enefield.eu), about 150 further units are being installed in several European countries. In addition, Vaillant started the production of a small-scale series in early 2014. Parallel to the practical test, the two partners are already working on new models. „Now, it’s all about decreasing production costs and increasing the lifetime of the equipment,“ says Jahn. 

The principle of the fuel cell has been known for over 175 years. So far, however, there has not been a market breakthrough. The main reason was the invention of the electric generator. It knocked the more complex fuel cell out of the running. Only in the 1960s was the technology put into practice by NASA in some Apollo moon missions. In the late 1990s, there were other projects in the automotive industry, which have so far not been able to prevail. The reasons are that the fuel cell is too complex, too expensive, and too unreliable. „In our project with Vaillant, we have made great strides to bring the technology close to the market. Vaillant is already producing a small-scale series, which is sold in funded projects to customers,“ says Jahn. „For the market breakthrough, the costs still have to be decreased significantly.“ 

The miniature power station for home use is based on a solid fuel cell (SOFC). SOFCs operate at a much higher temperature in comparison to competing approaches, such as the proton exchange membrane fuel cell (PEMFC), which is used in cars, for example. While PEMFCs only reach 80 degrees, SOFCs can reach up to 850 degrees. „This allows the SOFCs to be built much more simply and cheaply,“ says Jahn. 

The electrolyte of an SOFC only transfers oxygen ions, not electrons. Otherwise, there would be a short circuit. „Ceramic is particularly well suited as a material for the electrolyte. It has the desired conductivity and can also endure high temperatures,“ says Jahn. As a result, even without the use of precious metals, all reactions proceed smoothly, which is necessary for the direct conversion of chemical energy into electrical energy: If the fuel cell heater is connected to the gas network, a reformer initially converts the natural gas into a hydrogen-rich gas. This then reacts in the stack with the oxygen of the air in a noiseless „cold combustion“, producing power and heat.


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News - Rooibos helps protect against skin cancer...

News - Rooibos helps protect against skin cancer... | Physics | Scoop.it

People who spend a lot of time in the sun should consider using a skin care product containing rooibos extracts to prevent the development of skin cancer and to delay the onset of malignant tumours.

This is one of the findings of a recent study in which normal and cancerous skin cells were analysed to determine how exactly rooibos extracts in skin care products such as soaps, sun creams and lotions help stop the development of skin cancer.

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World's Smallest Engine Runs On A Single Atom

World's Smallest Engine Runs On A Single Atom | Physics | Scoop.it
Physicists are building a nano engine that runs on a single atom and will arguably be the most efficient ever made.

 

Like the one in your car, Johannes Roßnagel's engine is a four-stroke. In four steps it compresses and heats, then expands and cools. And as with any other engine, this cycle is repeated over and over again—transforming the changing temperature into mechanical energy. 

But Roßnagel's engine is no V-8. And it doesn't use internal combustion. Roßnagel, an experimental physicist at the University of Mainz in Germany, has conceived of and is in the process of building the world's tiniest engine, less than a micrometer in length. It is a machine so small it runs on a single atom. And in a recent paper in the journal Physical Review Letters, its inventors argue that, because of an interesting anomaly of quantum physics, this is also far and away the most efficient engine. 

The nano engine works like this: First, using tiny electrodes, the physicists trap a single atom in a cone of electromagnetic energy. "We're using a calcium-40 ion," Roßnagel says, "but in principle the engine could be built with just about any ion at all." This electromagnetic cone is essentially the engine's housing, and squeezes tightly over the atom. The physicists then focus two lasers on each end of the cone: one at the pointy end, which heats the atom, and another at the base of the cone, which uses a process called Doppler cooling to cool the atom back down. 

Because this heating and cooling slightly changes the size of the atom (more exactly, it alters the fuzzy smear of probability of where the atom exists), and the cone fits the atom so snuggly, the temperature change forces the atom to race back and forth along the length of the cone as the atom expands and contracts. For maximum efficiency, the physicists set the lasers to heat and cool at the same resonance at which the atom naturally vibrates from side to side. 

The result is that, like sound waves that build upon one other, the atom's oscillation between the two ends of the cone "gets accumulated, and becomes stronger and stronger," which can be harnessed, Roßnagel says. "If you imagine that you put a second ion by the cooler side, it could absorb the mechanical energy of our engine, much like a flywheel in a car engine." 


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Science/AAAS | Special Issue: Communication in Science: Pressures and Predators

Science/AAAS | Special Issue: Communication in Science: Pressures and Predators | Physics | Scoop.it

Science's Special Issue on Communication in Science: Pressures and Predators includes free news and reviews on the lack of scrutiny at open-access journals, the rarity of published negative studies, and publishing sensitive data.

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Lasers might be the cure for brain diseases such as Alzheimer's and Parkinson's

Lasers might be the cure for brain diseases such as Alzheimer's and Parkinson's | Physics | Scoop.it

Researchers at Chalmers University of Technology in Sweden, together with researchers at the Polish Wroclaw University of Technology, have made a discovery that may lead to the curing of diseases such as Alzheimer's, Parkinson's and Creutzfeldt-Jakob disease (the so called mad cow disease) through photo therapy.
The researchers discovered that it is possible to distinguish aggregations of the proteins, believed to cause the diseases, from the the well-functioning proteins in the body by using multi-photon laser technique.


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Designing exascale computers and beyond

Designing exascale computers and beyond | Physics | Scoop.it

Harvard's first large-scale digital computer, which came to be known as the Mark I, was conceived by Howard H. Aiken (A.M. '37, Ph.D. '39) and built by IBM. Fifty-one feet long, it was installed in the basement of what is now Lyman Laboratory in 1944, and later moved to a new building called the Aiken Computation Laboratory, where a generation of computing pioneers were educated and where the Maxwell Dworkin building now stands as part of the mechanism remains on exhibit in the Science Center.


The Mark I performed additions and subtractions at a rate of about three per second; multiplication and division took considerably longer. This benchmark was soon surpassed by computers that could do thousands of arithmetic operations per second, then millions and billions. By the late 1990s a few machines were reaching a trillion (1012) operations per second; these were called terascale computers, as tera is the Système International prefix for 1012. The next landmark—and the current state of the art—is the petascale computer, capable of 1015 operations per second. In 2010, Kaxiras' blood flow simulation ran on a petascale computer called Blue Gene/P in Jülich, Germany, which at the time held fifth place on the Top 500 list of supercomputers.


The new goal is an exascale machine, performing at least 1018 operations per second. This is a number so immense it challenges the imagination. Stacks of pennies reaching to the moon are not much help in expressing its magnitude—there would be millions of them. If an exascale computer counted off the age of the universe in units of a billionth of a second, the task would take a little more than 10 seconds.


And what comes after exascale? We can look forward to zettascale (1021) and yottascale (1024); then we run out of prefixes. The engine driving these amazing gains in computer performance is the ability of manufacturers to continually shrink the dimensions of transistors and other microelectronic devices, thereby cramming more of them onto a single chip. (The number of transistors per chip is in the billions now.) Until about 10 years ago, making transistors smaller also made them faster, allowing a speedup in the master clock, the metronome-like signal that sets the tempo for all operations in a digital computer. Between 1980 and 2005, clock rates increased by a factor of 1,000, from a few megahertz to a few gigahertz. But the era of ever-increasing clock rates has ended.


The speed limit for modern computers is now set by power consumption. If all other factors are held constant, the electricity needed to run a processor chip goes up as the cube of the clock rate: doubling the speed brings an eightfold increase in power demand. SEAS Dean Cherry A. Murray, the John A. and Elizabeth S. Armstrong Professor of Engineering and Applied Sciences and Professor of Physics, points out that high-performance chips are already at or above the 100-watt level. "Go much beyond that," she says, "and they would melt."


If the chipmakers cannot build faster transistors, however, they can still make them smaller and thus squeeze more onto each chip. Since 2005 the main strategy for boosting performance has been to gang together multiple processor "cores" on each chip. The clock rate remains roughly constant, but the total number of operations per second increases if the separate cores can be put to work simultaneously on different parts of the same task. Large systems are assembled from vast numbers of these multicore processors.


When the Kaxiras group's blood flow study ran on the Blue Gene/P at Jülich, the machine had almost 300,000 cores. The world's largest and fastest computer, as of June 2014, is the Tianhe-2 in Guangzhou, China, with more than 3 million cores. An exascale machine may have hundreds of millions of cores, or possibly as many as a billion.


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News - 25th Chris Engelbrecht Summer School 2014...

News - 25th Chris Engelbrecht Summer School 2014... | Physics | Scoop.it

The National Institute for Theoretical Physics (NITheP) hosted its 25th event this year. The topic of NITheP's flagship programme, the Chris Engelbrecht Summer School, was 'Nonlinear phenomena in Field Theory'.

Nonlinear problems are of interest to physicists, mathematicians and engineers and many other scientists, in that most systems are inherently nonlinear. 

Nonlinear systems cannot be broken up into simpler components and are therefore difficult to study. The School focused on methods that overcome these difficulties and presented various applications in different areas of physics. An everyday example of a nonlinear phenomenon that occurs in the research area of hydrodynamics is the weather. Simple changes in one part of the system produce complex effects throughout. This nonlinearity is one of the reasons why accurate long-term forecasts are impossible with current technology. On a more fundamental level, the formation of the hydrogen nucleus, the most essential building block of matter, could not be understood if the standard model of particle physics did not have nonlinear features. Besides topics from hydrodynamics and particle physics, nonlinear aspects of general relativity (cosmology), electrodynamics and condensed matter were taught at this year's School.

Prof Herbert Weigel (Chair of the School) commented that the School was particularly happy to welcome eight renowned lecturers from around the world that provided students with deep insights into the current frontiers of theoretical physics.

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Innovative Genomics Initiative launched around CRISPR-CAS9 genome editing technology

Innovative Genomics Initiative launched around CRISPR-CAS9 genome editing technology | Physics | Scoop.it
The University of California, Berkeley, and UC San Francisco are launching the Innovative Genomics Initiative (IGI) to lead a revolution in genetic engineering based on a new technology already generating novel strategies for gene therapy and the genetic study of disease.

 

The Li Ka Shing Foundation has provided a $10 million gift to support the initiative, establishing the Li Ka Shing Center for Genomic Engineering and an affiliated faculty chair at UC Berkeley. The two universities also will provide $2 million in start-up funds.

 

At the core of the initiative is a revolutionary technology discovered two years ago at UC Berkeley by Jennifer A. Doudna, executive director of the initiative and the new faculty chair. The technology, precision "DNA scissors" referred to as CRISPR/Cas9, has exploded in popularity since it was first published in June 2012 and is at the heart of at least three start-ups and several heavily-attended international meetings. Scientists have referred to it as the "holy grail" of genetic engineering and a "jaw-dropping" breakthrough in the fight against genetic disease. In honor of her discovery and earlier work on RNA, Doudna received last month the Lurie Prize of the Foundation for the National Institutes of Health.

 

"Professor Doudna's breakthrough discovery in genomic editing is leading us into a new era of possibilities that we could have never before imagined," said Li Ka-shing, chairman of the Li Ka Shing Foundation. "It is a great privilege for my foundation to engage with two world-class public institutions to launch the Innovative Genomics Initiative in this quest for the holy grail to fight genetic diseases."

 

In the 18 months since the discovery of this technology was announced, more than 125 papers have been published based on the technique. Worldwide, researchers are using Cas9 to investigate the genetic roots of problems as diverse as sickle cell anemia, diabetes, cystic fibrosis, AIDS and depression in hopes of finding new drug targets. Others are adapting the technology to reengineer yeast to produce biofuels and wheat to resist pests and drought.

 

The new genomic engineering technology significantly cuts down the time it takes researchers to test new therapies. CRISPR/Cas 9 allows the creation in weeks rather than years of animal strains that mimic a human disease, allowing researchers to test new therapies. The technique also makes it quick and easy to knock out genes in human cells or in animals to determine their function, which will speed the identification of new drug targets for diseases.

 

"We now have a very easy, very fast and very efficient technique for rewriting the genome, which allows us to do experiments that have been impossible before," said Doudna, a professor of molecular and cell biology in the California Institute for Quantitative Biosciences (QB3) and an investigator in the Howard Hughes Medical Institute at UC Berkeley. "We are grateful to Mr. Li Ka-shing for his support of our initiative, which will propel ground-breaking advances in genomic engineering."


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Direct measurements of the wave nature of matter, previously only known from theory

Direct measurements of the wave nature of matter, previously only known from theory | Physics | Scoop.it

At the heart of quantum mechanics is the wave-particle duality: matter and light possess both wave-like and particle-like attributes. Typically, the wave-like properties are inferred indirectly from the behavior of many electrons or photons, though it's sometimes possible to study them directly. However, there are fundamental limitations to those experiments—namely information about the wave properties of matter that is inherently inaccessible.

 

And therein lies a loophole: two groups used indirect experiments to reconstruct the wave structure of electrons. A.S. Stodolna and colleagues manipulated hydrogen atoms to measure their electron's wave structure, validating more than 30 years of theoretical work on the phenomenon known as the Stark effect. A second experiment by Daniel Lüftner and collaborators reconstructed the electronic structure of individual organic molecules through repeated scanning, with each step providing a higher resolution. In both cases, the researchers were able to match theoretical predictions to their results, verifying some previously challenging aspects of quantum mechanics.

 

Neither a wave nor a particle description can describe all experimental results obtained by physicists. Photons interfere with each other and themselves like waves when they pass through openings in a barrier, yet they show up as individual points of light on a phosphorescent screen. Electrons create orbital patterns inside atoms described by three-dimensional waves, yet they undergo collisions as if they were particles. Certain experiments are able to reconstruct the distribution of electric charge inside materials, which appears very wave-like, yet the atoms look like discrete bodies in those same experiments.

 

The wave functions in the Stark effect have a peculiar mathematical property, one which Stodolna and colleagues recreated in the lab. They separated individual hydrogen atoms from hydrogen sulfide (H2S) molecules, then subjected them to a series of laser pulses to induce specific energy transitions inside the atoms. By measuring the ways the light scattered, the researchers were able to recreate the predicted wave functions—the first time this has been accomplished. The authors also argued that this method, known as photoionization microscopy, could be used to reconstruct wavefunctions for other atoms and molecules.

 

Lüftner and colleagues took a different approach and examined the wave functions of organic molecules chemically attached (adsorbed) on a silver surface. Specifically, they looked at pentacene (C22H14) and the easy-to-remember compound perylene-3,4,9,10-tetracboxylic dianhydride (or PTCDA, C24H8O6). Unlike hydrogen, the wave functions for these molecules cannot be calculated exactly. They usually require using "ab initio" computer models.

 

The researchers were particularly interested in finding the phase, that bit of the wave function that can't be measured directly. They determined that they could reconstruct it by using the particular way the molecules bonded to the surface, which enhanced their response to photons of a specific wavelength. The experiment involved taking successive iterative measurements by exciting the molecules using light, then measuring the angles at which the photons were scattered away.

 

Reconstructing the phase of the wave function required exploiting the particular mathematical form it took in this system. Specifically, the waves had a relatively sharp edge, allowing the researchers to make an initial guess and then refine the value as they took successive measurements. Even with this sophisticated process, they were only able to determine the phase to an arbitrary precision—something entirely to be expected from fundamental quantum principles. However, they were able to experimentally reconstruct the entire wave function of a molecule. There was previously no way to check whether our calculated wave functions were accurate or not.

 

REFERENCES:

Physical Review Letters, 2013. DOI: 10.1103/PhysRevLett.110.213001 and
PNAS, 2013. DOI: 10.1073/pnas.1315716110  (About DOIs).


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6th African Laser Centre Workshop - 21 to 23 Nov 2013

6th African Laser Centre Workshop - 21 to 23 Nov 2013 | Physics | Scoop.it

The purpose of the symposium is to bring together ALC grant holders and partners from across Africa, and students at South African universities who are working in the various ALC sponsored projects. 

Stellenbosch University, Faculty of Science's insight:

It is also the tenth anniversary of the ALC and it's going to be celebrated with a laser show and lots of cake!

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