Shma Shot about Physics

As the researchers note, fabricating the high-performance sub-5-nanometer silicon nanowire transistors is relatively simple compared to other methods of nanowire fabrication, which use bottom-up methods and doped junctions or channel doping. One particular application that the researchers plan to pursue is making use of the nanowires to produce inexpensive, ultrasensitive biosensors, since biosensor sensitivity increases as nanowire diameter decreases.
?¡ãAs essential by our funding (NSF Profession Award), our immediate plan is to explore biosensing of protein with these varieties of tiny nanowire transistors,?¡À Hu stated. ?¡ãWe believe such small-diameter nanowires with intrinsic high performance can have a major impact on biosensing, as they are expected to provide ultimate sensitivity down to a single molecule with a better signal-to-noise ratio.?¡À
In addition to biosensing, the new high-performance transistors could have an impact on CMOS scaling, which is becoming increasingly difficult. The researchers are currently looking for funding in order to explore this area.
?¡ãThese transistors can have an impact on CMOS scaling due to the fact that performance actually increases with decreasing diameter,?¡À Hu stated. ?¡ãArrays of nanowire transistors with tiny nanowires could be produced to achieve high performance without requiring new processing techniques. In fact, the processing can even be simplified over current techniques, as our nanowire transistors do not use highly doped complementary junctions for source/drain; eliminating high doped junctions alleviates many of the current issues in scaling down CMOS processing techniques to the nanoscale.
?¡ãAt large, my personal viewpoint is that silicon still has a lot of potential for nanoelectronics, along with the industry may want to consider supporting study in silicon nanowire or quantum wire devices and new architectures to fully unleash the potential of silicon. Everyone is researching graphene, which is a great material of course, but we may possibly not want to ignore the potential of silicon, as we show that effective hole mobility could be over 1200.

Channelrhodopsins respond to light since they contain a chromophore molecule (retinal) that can switch among two different shapes. The activation power, the amount of power that it takes to switch the chromophore between these two states, is about 240 kJ/mol, which corresponds to the power of a blue photon (480nm). If we wanted to engineer a rhodopsin to become sensitive to radio frequencies, what activation power would we want our chromophore to have? Well, let’s take the frequency of one particular of my favorite radio stations 106.7 MHz (let’s round to 100 MHz), which would correspond to a wavelength of about 3 m, and an energy of about 0.04 kJ/mol. Therefore, the activation power necessary to change the shape of the chromophore molecule would have to become about 0.04 kJ/mol.

Do you see the problem? At human body temperature (37oC, 310K), the amount of thermal energy accessible is about two.6 kJ/mol. This means that thermal energy alone will be enough to activate our hypothetical radio-sensitive rhodopsin! The protein would not actually be able to sense radio waves since it would always be on regardless of regardless of whether or not radio waves were present.

If you look at calculations like these, you’ll see that it is not an accident that animal vision is limited to a tiny range of the EM spectrum ranging from the near IR to the near UV. It is determined, rather, by the laws of physics. At frequencies significantly below the visible region, you get to the point exactly where thermal power becomes more energetic than the photons and a chromophore would not be able to distinguish thermal energy from the absorption of photons. At frequencies significantly above the visible region, you get into the range of ionizing radiation, photons so energetic that their energies are comparable to the activation energies for breaking chemical bonds.

In the September 1, 2008, issue of Cancer Research, a journal of the American Association for Cancer Research, the scientists report that subjects who lived close to the blast sites, were comparably young at the time, and created the cancer quickly once they reached adulthood, were likely to have a chromosomal rearrangement recognized as RET/PTC that is not very frequent in adults who develop the disease.
“Recent in vitro and in vivo studies suggest that a single genetic event inside the MAP kinase-signaling pathway could be sufficient for thyroid cell transformation and tumor improvement,” mentioned the study’s lead author, Kiyohiro Hamatani, Ph.D., laboratory chief, Department of Radiobiology and Molecular Epidemiology at the Radiation Effects Research Foundation (RERF) in Hiroshima.
“Thyroid cancer is associated with exposure to external or internal ionizing radiation.Elucidation of mechanisms of radiation-induced cancer in humans, especially early steps and pathways, has potential implications for epidemiological risk analyses, early clinical diagnosis, and chemopreventive interventions,” Hamatani said.
He adds that there are many irradiated populations worldwide that have been shown to have an increase in thyroid cancer, and that children exposed to radioactive fallout from the 1986 Chernobyl nuclear power plant accident who develop papillary thyroid cancer have also been found to have RET/PTC rearrangements, although they are slightly different.
This study is part of the foundation’s long running follow-up analysis on 120,000 atomic bomb survivors. In the course of 1958 to 1998, the study found about 470 thyroid cancer cases of which the estimated number of excess cases attributable to radiation is 63. About 90 percent of thyroid cancer among the survivors is of the papillary type.
Hamatani and colleagues from across Japan made a comparison between adult-onset papillary thyroid cancers with RET/PTC rearrangements and those with a BRAF mutation. Much more than 70 percent of adult onset papillary thyroid cancer in non-exposed patients is associated with mutations within the BRAF gene.
The researchers looked at the genetic profile of cancer patients inside the RERF’s follow-up study–50 patients who were exposed to atomic bomb radiation and 21 patients who were not. Three factors were found to become independently associated with the improvement of adult-onset papillary thyroid cancer with RET/PTC rearrangements. They were greater radiation dose, shorter time elapsed since radiation exposure, and younger age in the time of the bombings, Hamatani says.
“That means that a younger person living close to the bombing web site will be more likely to have adult onset thyroid cancer having RET/PTC rearrangements,” he said. “This is the first time this has been shown.”
The findings also suggest that in childhood papillary thyroid cancer RET/PTC rearrangements might be considerably less clearly associated with radiation exposure, compared with adult-onset cancer, simply because RET/PTC rearrangements are frequent in childhood papillary thyroid cancer patients regardless of history of radiation exposure.
The researchers do not know exactly how radiation is involved in the occurrence of RET/PTC rearrangements. “It could be either by direct DNA damage or by other pathways like a result of radiation-induced genomic instability,” Hamatani stated.

The National Institutes of Health-led study examined much more than 12,500 folks who had been under 18 at the time of the Chernobyl accident on April 26, 1986, and who lived near the accident website in one of three parts of Ukraine.
Each person’s thyroid radioactivity levels had been measured within two months of the accident, and they had been screened for thyroid cancer four times, beginning as early as 12 years after the disaster and continuing for 10 years.
Sixty-five of those in the study were diagnosed with thyroid cancer.
When researchers examined the cancer risk in relation to how a lot exposure to radioactive iodine-131 (I-131) each person received, they found a two-fold increase for each additional gray, an international unit of absorbed radiation.
“The researchers found no evidence, throughout the study time period, to indicate that the increased cancer risk to those who lived in the area in the time of the accident is decreasing over time,” mentioned the study.
Overall, the “clear dose-response relationship, in which larger absorption of radiation from I-131 led to an increased risk for thyroid cancer… has not seemed to diminish over time,” it said.
The study was carried out by an international team of scientists and was headed by the National Cancer Institute, which is part of the NIH. It appears within the March 17 issue of the journal Environmental Well being Perspectives.
Separate studies involving people who survived atomic bombs have shown that cancer risk begins to decline after 30 years, but remains high after 40 years compared to the general population.
The study authors said more follow up is needed to judge if or when such a decline may be occurring among survivors of Chernobyl, the worst nuclear accident ever.
The disaster, whose memory has been revived with Japan’s attempts to contain overheating at its Fukushima nuclear plant after a 9.0-magnitude earthquake and massive tsunami, involved a full-scale nuclear explosion in the number-four reactor at Chernobyl as a result of human error throughout a botched testing procedure.
Some five million individuals are believed to have been affected by the disaster in Belarus, Russia and Ukraine, exactly where millions of acres (hectares) of agricultural and forest land remain contaminated.
The disaster’s death toll is hotly debated. UN agencies estimate up to 9,000 people could be expected to die as a direct consequence of the accident, and that the disaster will end up costing hundreds of billions of dollars.
Environmental groups like Greenpeace say up to 100,000 people could die.

Was the increase in cancer caused by the radioactive fallout from Chernobyl or could it be explained by other circumstances? New study from Link?ping University provides scientific support for the Chernobyl connection. ?¡ãThis issue is important due to the fact the indicated increased risk may possibly come to influence the prevailing exposure limits for the population. Enhanced knowledge of the risks entailed by radioactive radiation is key to work for radiation safety and makes it possible to prevent diseases,?¡À says Martin Tondel, a physician and researcher in environmental medicine who will soon be defending his doctoral dissertation Malignancies in Sweden after the Chernobyl Accident in 1986. In two studies utilizing different methods, Martin Tondel has shown a modest but statistically significant increase within the incidence of cancer in northern Sweden, where the fallout of radioactive cesium 137 was at its most intense. The cancer risk increased with rising fallout intensity: up to a 20-percent increase inside the highest of six categories. This means that 3.8 percent of the cancer cases up to 1999 can be ascribed to the fallout. This increased risk, in turn, is 26 times greater than the latest risk estimate for the survivors of the atom bombs in Hiroshima and Nagasaki, whose exposure was numerous times larger. The increase in Tondel?¡¥s studies came a remarkably short time after the disaster, since it is usually assumed that it takes decades for cancer to develop. The dissertation discusses the interpretation of the investigation findings from the perspective of the theory of science. The conclusion is that there is scientific support for a connection amongst the radioactive fallout as well as the increase inside the number of cancer cases.

Most importantly, they have stockpiled and are producing plans to give out potassium iodide – pills that can keep radioactive iodine from becoming taken up by the thyroid gland and causing cancer.
“Those are all preventable cancers” if the protective pills are taken right after exposure, said University of New Mexico radiologist Dr. Fred Mettler. He led an international group that studied well being effects of the Chernobyl disaster and is a U.S. representative to the United Nations on radiation safety.
At Chernobyl “they had millions of square kilometers to cover and it was all rural areas and they didn’t really have anything stockpiled,” he said.
The Russian reactor also lacked a containment vessel like those in Japan as well as the Usa to prevent or minimize release of the more dangerous varieties of radioactive supplies, Mettler mentioned.
“Right now it’s worse than Three Mile Island,” Olander stated, but isn’t near the Chernobyl situation. Some radioactive iodine was released before the latest crisis Tuesday. Iodine is relatively short-lived, and potassium iodide pills might be used to block its uptake.
Of greater concern is the release of cesium, which officials had said was released in tiny quantities earlier. Cesium is absorbed throughout the body – not just by the thyroid – and stays in organs, tissue and also the environment a lot longer, Mettler explained.
Cesium particles are relatively large and heavy, so they would not likely travel far inside a plume. Considerably of it would drop near the reactor website, and officials hope, may be carried by winds east over the Pacific Ocean exactly where it would fall harmlessly, Mettler said.
Any release of cesium is a concern environmentally and for health, said Jacqueline Williams, a radiation biologist and safety expert at the University of Rochester Medical Center in upstate New York.
“Prior to Chernobyl, we believed that the cesium could be diluted out, that once the cloud went through and it rained, the cesium could be washed out. What we found out was there was an accumulation of cesium in specified forms of vegetation, and it accumulated instead of diluted,” she mentioned.
Animals fed on the vegetation and became contaminated, and meat and milk had been affected.
“You can’t be quite so blase about the fallout,” Williams stated.
At Three Mile Island, however, “the public wellness risk was close to zero since the radiation was contained within the internet site itself,” Williams said.
Mettler agreed. The analysis he led in Russia documented 6,000 to 7,000 additional cases of thyroid cancer in people who were children and teens when Chernobyl occurred, “and there are questionable increases of leukemia inside the cleanup workers but it’s not certain.”
And had been there long-lasting problems from Three Mile Island?
“Not that most of the scientific community believes,” Mettler said.

Japanese officials mentioned that more radiation was released at a nuclear plant disastrously damaged by last week’s tsunami. Prime Minister Naoto Kan stated radiation had spread from four reactors.
“The level seems very high, and there is still a very high risk of a lot more radiation coming out,” he stated.
Thyroid cancer is the most immediate risk, and the Japanese government made plans to distribute potassium iodide pills to prevent it. Worse situation scenarios – lots of radioactive fallout – can lead to other cancers years later.
Even a meltdown would not necessarily mean medical doom, experts said. It depends on the quantity and type of radioactive materials.
Donald Olander, professor emeritus of nuclear engineering at the University of California at Berkeley, stated even the significantly larger levels of radiation are “not a well being hazard.”
The planet has seen two big nuclear reactor scares – in 1986 at the Chernobyl plant in the Ukraine, and in 1979 at the Three Mile Island plant in Pennsylvania.
At Three Mile Island, even though a quarter of the reactor core melted, the steel containment structure held. The radiation released was so minuscule that it did not threaten wellness – the equivalent of a chest X-ray to neighborhood folks.
At Chernobyl, where there was no containment vessel, far more radioactive materials was released, and of a far more dangerous type than at Three Mile Island. It stayed in soil and got into plants in the Ukraine, contaminating milk and meat for decades. Thousands of children created thyroid cancer from radiation exposure, and scientists are still working to document other achievable well being problems.
The lessons have not been lost on the Japanese as they grapple with the Fukushima Dai-ichi power plant, whose cooling systems failed after a power outage from the massive earthquake last week.
They have evacuated 180,000 individuals from areas near the troubled reactors, exactly where relatively minimal fallout was mostly confined at first. They’ve told folks still within the area to wear masks, which can keep radioactive particles from getting inhaled.

Inside the situation of Chernobyl there was a large graphite fire that lifted radioactivity to high altitudes and spread it over large distances,” he said. “To the best of my knowledge, there has not been that process inside the situation of Fukushima.”
Highly sensitive equipment to detect radiation was first developed to make sure countries had been observing the nuclear test ban treaty, Higley explained, and more recently there has been a focus on preventing terrorism.
In addition, she noted, iodine-131 is typically utilised in medical treatments, meaning it might be released around manufacturing plants and also in wastewater from hospitals where individuals undergo treatment. Indeed, she noted, radiation detectors are scattered around her university and at others where researchers work with radioactive isotopes.
Recent increases in levels of iodine and cesium are getting attributed to the Japan release due to the fact of the timing and tracking of winds from the region. Southern utility companies on Monday mentioned air monitors at power plants in Florida and South Carolina had detected iodine-131, which they concluded was coming from Japan.
Unlike Chernobyl when the isotopes were blasted high into the stratosphere where it could spread quickly, the radiation from Japan has remained inside the lower atmosphere, noted Ross J. Salawitch, a University of Maryland researcher who has been tracking the plume from Japan.
Jeffrey Stehr, an atmospheric study scientist in the University of Maryland, said that while the radiation from Japan has been widely detected, it could take as much as a year to spread throughout the Northern Hemisphere. It could take one more year before it is widespread inside the Southern Hemisphere simply because of blocking at the equator caused by rising air currents exactly where winds from north and south collide.
While memories of the Chernobyl disaster in what is now Ukraine have raised concerns, the quantities of radioactive material released in Japan have been a lot less than at that event., mentioned William H. Miller, a professor in the University of Missouri Research Reactor.
As much as 5 percent of the core at Chernobyl went directly into the atmosphere, Miller explained, while that has not occurred at Fukushima.
“This is not anywhere close to Chernobyl,” said Miller.
In its study of Chernobyl, the United Nations Scientific Committee on the Effects of Atomic Radiation noted that in that disaster large quantities of radioactive substances had been released into the air for about 10 days as the reactor burned.
“The radioactive cloud dispersed over the entire Northern Hemisphere, and deposited substantial amounts of radioactive materials over large areas of the former Soviet Union and some other countries in Europe,” contaminating land and water, the report said.
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The improvement of super-sensitive equipment to detect radiation is each a blessing along with a curse, allowing scientists to monitor supplies released in nuclear accidents, but also causing unnecessary be concerned, mentioned Kathryn Higley, director of the nuclear engineering and radiation well being physics at Oregon State University.
Traces of radioactive cesium and iodine are becoming reported from Nevada to Vermont, South Carolina to Massachusetts, thanks to equipment that Higley says can detect material “many orders of magnitude beneath what could be hazardous.”
The traces of radiation outside of Japan are “absolutely of no concern,” added Ahmed Hassanein, head of nuclear engineering in the Purdue School of Nuclear Engineering.
Curiously, one particular spot where very small quantities of the radioactive isotopes had been detected was Las Vegas’ Atomic Testing Museum, about 65 miles from the desert web site exactly where the Usa tested atomic bombs within the 1950s.
Ted Hartwell, manager of environmental monitoring in the Desert Study Institute, said he’s particular the isotopes came from Japan simply because they’re not normally detected in Nevada. But he stated the readings had been far below levels that could pose any well being risks.
Gerhard Wotawa of Austria’s Central Institute for Meteorology and Geodynamics, mentioned the amounts of radiation detected so far had been a fraction of what individuals are usually exposed to, adding that medical doctors, pilots and other folks are usually confronted with much larger concentrations.
He also said that several forms of material flung into the air at the Chernobyl plant 25 years ago usually are not turning up within the aftermath of the Fukushima accident because there has been no explosion to propel these heavier components inside the atmosphere.
Graham Andrew, a senior aide to International Atomic Power Agency chief Yukiya Amano, mentioned it was too early to compare Chernobyl and Fukushima, but also suggested that to some degree the two accidents are like comparing apples and oranges.

We’re inside the midst of an details revolution, so much so that even lay individuals know the standard details about information?ahow it could be encoded in bits 0 and 1, stored, retrieved, transmitted, and processed utilizing logic gates like AND and NOT. This revolution is determined by our ability to treat data in an abstract way, largely independent of its physical embodiment, which could be as diverse as a hole inside a punch card, a voltage in a wire, or the magnetization of a speck of iron oxide. The field of Info Physics treats ways in which it nonetheless fruitful to reintegrate physical laws and principles into the science of information. These contain:
Thermodynamics: Processing details consumes power and generates waste heat, and the amount turns out to depend both on hardware and the nature of the logic operations getting carried out. The founder of our group, the late Rolf Landauer, throughout his long profession at IBM Study, continually emphasized the connection in between info processing and physics, and discovered the connection between logical irreversibility and heat generation now known as Landauer’s principle.
Quantum effects: Quantum phenomena like entanglement and interference were neglected within the classical theory of info processing developed by Shannon, Turing, von Neumann and their contemporaries. In retrospect this was a mistake. Which includes quantum effects, and indeed abstracting them away from any certain physical embodiment, results in a more coherent and strong theory of details processing, too as generating achievable information-processing feats unachievable with conventional ?¡ãclassical?¡À details, notably quantum cryptography and quantum computational speedups. In location of bits the new quantum details theory has qubits, that are capable of entanglement and superposition, and interact with a single yet another through quantum gates.
Fault-tolerance: Any genuine physical data processing apparatus, no matter whether man-made or biological, is topic to errors. To produce computing systems scalable in the presence of errors, a fault-tolerant architecture is needed. This old dilemma has grow to be acute within the case of quantum computer systems, where a considerable gap remains to be closed in between experimentally accessible error rates and the thresholds at which fault tolerant architectures would take hold.
Physical Complexity: How can numerous mathematical notions of complexity, like time/space complexity, parallel complexity, and algorithmic details, be utilized to characterize the complexity of physical states, phase transitions, and the behavior of systems at and away from thermal equilibrium. Are there physical systems or dynamics which might be uncomputable within the mathematical sense?
Physical Authentication: Can our understanding of the computational complexity be utilized to authenticate physical objects and evolutions as genuine, instead of forged or simulated?