Developing novel materials from the atoms up goes faster when some of the trial and error is eliminated. A new Rice University and Montreal Polytechnic study aims to do that for graphene and boron nitride hybrids.
Thomas Scheff would like psychologists to talk about emotion — not simply to share feelings, but to advance science. According to the emeritus professor of sociology at UC Santa Barbara, intuition could be the catalyst that enables psychology to progress in areas in which it has stagnated.
His research, “Three Scandals in Psychology: The Need for a New Approach,” is published in the Review of General Psychology.
Scheff argues that research into aggression catharsis, stigma and self-esteem have become bogged down because scientific method in psychology is blind to the insights that intuition — that which doesn’t require “rational” thought — can provide.
Scheff points to the example of Danish astronomer Tycho Brahe, who spent his life trying to determine the orbit of Venus. Although his observations were meticulous, the science was sabotaged by the common belief that the planets revolved around the Earth. After Brahe’s death, Johannes Kepler, working with Brahe’s data, solved the problem through an accident of intuition.
“Scientific and other methods, no matter how scrupulously applied, are helpless in the face of misleading tropes,” Scheff writes in the paper. He defines tropes as false assumptions — ideas taken for granted that may be untrue or only partially true.
Aggression catharsis, or the venting of anger, is a trope embraced by the public, he continues. Psychologists have shown that venting doesn’t work, but they’ve erred in thinking that there is no such thing as catharsis, according to Scheff. He argues that catharsis is real and achieved through “pendulation,” the process by which people alternate between reliving an experience and watching themselves relive it.
“You’re going back and forth between the emotional moment and the safe present,” he said. “Some writers call it the safe zone. You’ve found the safe zone where you can relive fear that’s actually pleasant. That’s why young people like to ride rollercoasters; because they feel safe. The rollercoaster is a safe machine and therefore they can feel fear in a safe zone.”
Scheff recalled that venting was an accepted therapy for many years, despite its
evident failure. Working as a marriage counselor decades ago, he was encouraged to use venting in his practice. “My teachers told me that the way to deal with angry people was to have them beat on a pillow with a tennis racquet and yell at the pillow,” he said. “It never worked. I never had one client who was helped by that.”
Stigma, which has been studied extensively, is another area that most psychologists get wrong, according to Scheff. The problem, he explained, is that stigma usually is defined as a mark of disgrace as a result of some humiliation. However, he argued, stigma is a certain kind of shame that is actually an emotion — something science poorly understands. “Scholars are just as confused by emotions as the public,” he said. “They’re studying an emotion, but they don’t know it, because it’s hidden in modern societies.”
Shame is particularly misunderstood, Scheff claimed, because of its social toxicity. “Why the reluctance to use shame? In an individualistic society, shame is shameful,” he said. “It’s shame about shame. You know what happens in a theater fire, where people get afraid because others are frightened? They get into a loop and they do horrible things. That’s a fear cycle, a fear loop. Modern societies, because they’re so individualistic, they’re in shame loops.”
Scheff has a harsh assessment of the study of self-esteem. He noted that over the past 50 years more than 20,000 studies have used some 200 self-esteem scales. Their failure, he said, is clear; the scales’ ability to predict behavior is less than 5 percent.
“Despite the failure and the critics, researchers have continued to research with self-esteem scales, as if they want to repeat the Brahe error forever,” he said, adding that the problem is one of researchers confusing thoughts with emotions. Future studies, he noted, could split the scale into cognitive and emotional components.
As someone who has studied emotions for 40 years, Scheff noted that psychology and the public will progress only after the meaning and ramifications of emotions are addressed. “We need to be able to talk about them to ourselves and others,” he said. “Feel and reveal is the secret.”
Source: University of California – Santa Barbara.
Published on 26th June 2015
Researchers at University of California, San Diego School of Medicine have documented the accuracy of three new tests for more rapidly diagnosing drug-resistant forms of tuberculosis (TB), which are much harder and more expensive to treat and which, experts say, represent a major threat to global public health.
The study is published online in the current issue of PLOS ONE.
“Our study shows that TB testing that once took two to three months can now be done in as little as a day,” said co-author Richard Garfein, PhD, professor in the Division of Global Public Health at UC San Diego School of Medicine. “This means we can put people on the right medications sooner, spare them the toxic effects of drugs that are ineffective and prevent the development of drug resistant forms of TB that can occur when the wrong medications are given.”
Although rates of TB are declining in the United States due to effective control measures, it remains one of the world’s deadliest infectious diseases, causing (or contributing to) an estimated 1.5 million deaths in 2013, according to the World Health Organization. TB is also the leading killer of people who have HIV.
For the study, sputum (a mixture of saliva and mucus coughed up from the lungs) from 1,128 study participants at TB clinics in India, Moldova and South Africa were examined using three rapid tests for detecting drug-resistant forms of TB. Two of these tests use molecular techniques to look for genetic mutations in the pathogen’s DNA that confer resistance to antibiotics. The third test employs a low-cost and easy-to-use version of the standard bacterial culture technique, making it suitable for resource-limited community clinics and hospitals. An estimated 95 percent of TB deaths globally occur in low- and middle-income countries.
Results from the rapid tests were then compared to the reference standard technique for detecting resistance to seven of the most important anti-TB drugs. These comparisons showed that all three rapid assays accurately identified resistance to first- and second-line oral antibiotic treatments (isoniazid, rifampin, moxifloxacin and ofloxacin). They were less accurate but still very good at detecting resistance to injectable antibiotics (amikacin and capreomycin) typically administered to those with multi-drug resistant TB. The rapid tests performed poorly in detecting resistance to only one drug, the injectable antibiotic kanamycin, which is also used to treat multi-drug resistant TB.
The study also documented the time it took to obtain results. The molecular techniques showed themselves to be superior, with a mean time of 1.1 days for both DNA testing methods; 14.3 days for the rapid culture method; and 24.7 days for the reference standard test.
“The results from this international collaboration take us one step closer to achieving the World Health Organization’s goal of reducing deaths due to TB by 95 percent by 2050,” said lead author Antonino Catanzaro, MD, Professor Emeritus in the Division of Pulmonary, Critical Care and Sleep Medicine. “Rapid, accurate drug susceptibility tests are critical for physicians. They help us ensure that patients receive the appropriate anti-TB drugs to combat their specific form of tuberculosis. When patients receive the proper drug treatment, we see a large reduction in TB mortality.”
Source: University of California – San Diego.
Published on 9th September 2015
Researchers have created a new “plasmonic oxide material” that could make possible devices for optical communications that are at least 10 times faster than conventional technologies.
In optical communications, laser pulses are used to transmit information along fiber-optic cables for telephone service, the Internet and cable television.
Researchers at Purdue University have shown how an optical material made of aluminum-doped zinc oxide (AZO) is able to modulate – or change – how much light is reflected by 40 percent while requiring less power than other “all-optical” semiconductor devices.
“Low power is important because if you want to operate very fast – and we show the potential for up to a terahertz or more – then you need low energy dissipation,” said doctoral student Nathaniel Kinsey. “Otherwise, your material would heat up and melt when you start pushing it really fast. All-optical means that unlike conventional technologies we don’t use any electrical signals to control the system. Both the data stream and the control signals are optical pulses.”
Being able to modulate the amount of light reflected is necessary for potential industrial applications such as data transmission.
“We can engineer the film to provide either a decrease or an increase in reflection, whatever is needed for the particular application,” said Kinsey, working with a team of researchers led by Alexandra Boltasseva, an associate professor of electrical and computer engineering, and Vladimir M. Shalaev, scientific director of nanophotonics at Purdue’s Birck Nanotechnology Center and a distinguished professor of electrical and computer engineering. “You can use either an increase or a decrease in the reflection to encode data. It just depends on what you are trying to do. This change in the reflection also results in a change in the transmission.”
Findings were detailed in a research paper appearing in July in the journal Optica, published by the Optical Society of America.
The material has been shown to work in the near-infrared range of the spectrum, which is used in optical communications, and it is compatible with the complementary metal–oxide–semiconductor (CMOS) manufacturing process used to construct integrated circuits. Such a technology could bring devices that process high-speed optical communications.
The researchers have proposed creating an “all optical plasmonic modulator using CMOS-compatible materials,” or an optical transistor.
In electronics, silicon-based transistors are critical building blocks that switch power and amplify signals. An optical transistor could perform a similar role for light instead of electricity, bringing far faster systems than now possible.
The Optica paper, featured on the cover of the journal, was authored by Kinsey, graduate students Clayton DeVault and Jongbum Kim; visiting scholar Marcello Ferrera from Heriot-Watt University in Edinburgh, Scotland; Shalaev and Boltasseva.
Exposing the material to a pulsing laser light causes electrons to move from one energy level called the valence band to a higher energy level called the conduction band. As the electrons move to the conduction band they leave behind “holes” in the valance band, and eventually the electrons recombine with these holes.
The switching speed of transistors is limited by how fast it takes conventional semiconductors such as silicon to complete this cycle of light to be absorbed, excite electrons, produce holes and then recombine.
“So what we would like to do is drastically speed this up,” Kinsey said.
This cycle takes about 350 femtoseconds to complete in the new AZO films, which is roughly 5,000 times faster than crystalline silicon and so fleeting that light travels only about 100 microns, or roughly the thickness of a sheet of paper, in that time.
“We were surprised that it was this fast,” Kinsey said.
The increase in speed could translate into devices at least 10 times faster than conventional silicon-based electronics.
The AZO films are said to be “Epsilon-near-zero,” meaning the refractive index is near zero, a quality found normally in metals and new “metamaterials,” which contain features, patterns or elements that enable unprecedented control of light by harnessing clouds of electrons called surface plasmons. Unlike natural materials, metamaterials are able to reduce the index of refraction to less than one or less than zero. Refraction occurs as electromagnetic waves, including light, bend when passing from one material into another. Each material has its own refraction index, which describes how much light will bend in that particular material and defines how much the speed of light slows down while passing through a material.
The pulsing laser light changes the AZO’s index of refraction, which, in turn, modulates the amount of reflection and could make higher performance possible.
“If you are operating in the range where your refractive index is low then you can have an enhanced effect, so enhanced reflection change and enhanced transmission change,” he said.
The researchers “doped” zinc oxide with aluminum, meaning the zinc oxide is impregnated with aluminum atoms to alter the material’s optical properties. Doping the zinc oxide causes it to behave like a metal at certain wavelengths and like a dielectric at other wavelengths.
A new low-temperature fabrication process is critical to the material’s properties and for its CMOS compatibility.
“For industrial applications you can’t go to really high fabrication temperatures because that damages underlying material on the chip or device,” Kinsey said. “An interesting thing about these materials is that by changing factors like the processing temperature you can drastically change the properties of the films. They can be metallic or they can be very much dielectric.”
The AZO also makes it possible to “tune” the optical properties of metamaterials, an advance that could hasten their commercialization, Boltasseva said.
The ongoing research is based at Purdue’s Birck Nanotechnology Center and is funded by the Air Force Office of Scientific Research, a Marie Curie Outgoing International Fellowship, the National Science Foundation, and the Office of Naval Research.
Source: Purdue University
Published on 31st July 2015
Slavery was abolished more than 150 years ago, but its effects are still felt today in K-12 education in the South, according to a new Rice University study, “How the Legacy of Slavery and Racial Composition Shape Public School Enrollment in the American South.”
“Our results suggest that the legacy of slavery contributes to black-white education disparities through greater public-private school racial segregation,” said Heather O’Connell, co-author and postdoctoral fellow at Rice’s Kinder Institute for Urban Research.
Using regression analysis to explain differences in the degree of attendance disparities across most counties in the South, researchers found a correlation between historical geographic slave concentration and modern day K-12 school segregation. An increase in slave concentration is related to greater underrepresentation of white students in public schools.
Overall, the proportion of black students in a county who are enrolled in public schools is an average of 17 percent higher than white students. But that gap in public school attendance is even larger where slaves were more heavily concentrated, increasing by just over 1 percentage point with every 10 percentage-point increase in slave concentration.
Soon after slavery was abolished, the former slaves quickly organized schools, according to the study. However, white resistance was substantial. Several other separation tactics were employed along the way, but the construction of private schools was the most recent action taken to maintain a segregated school system.
“As blacks began to enter the local white public schools, private schools cropped up seemingly overnight,” the researchers said.
Private schools are important for explaining contemporary school segregation. The study found that having more private schools in a county is related to a greater underrepresentation of white students in public schools. But this relationship doesn’t explain why slavery still matters for public-private school segregation.
The researchers found the same is true when considering another important county characteristic — the relative size of the black population. Generally speaking, a larger concentration of black students is related to increased separation of white students. The findings of this study support this “white flight” argument, but add another dimension.
“Whites are increasingly not enrolled in public schools in counties with higher black concentrations and are instead increasingly enrolled in private schools,” the researchers said. But O’Connell said that the role of black population concentration plays out primarily in states where slavery was most strongly rooted.
The study found that the black population concentration relationship only holds in the original Confederate States, or Deep South: Alabama, Florida, Georgia, Louisiana, Mississippi, South Carolina and Texas.
Even with this added dimension, the researchers were unable to identify tangible county characteristics that explain why slave concentration from 1860 is related to contemporary school enrollment patterns. The relationship is complex, but the authors urge greater attention to how slavery relates to contemporary racial disparities.
“Understanding the role of our slavery history provides insight into the structural foundations supporting this segregation, which might be valuable to efforts to reverse dangerous trends in school resegregation that have been increasing across the South over the last few decades,” O’Connell said.
Source: Rice University
Published on 26th June 2015
In some patients, aggressive cancers can become resistant to chemotherapy and radiation treatments. In a paper published in the journal Nature Communications, University of California, San Diego School of Medicine researchers identified a pathway that causes the resistance and a new therapeutic drug that targets this pathway.
New technology developed by UC Berkeley bioengineers promises to make a workhorse lab tool cheaper, more portable and many times faster by accelerating the heating and cooling of genetic samples with the switch of a light.
Artist’s rendering of photonic PCR on a chip using light to rapidly heat and cool electrons at the surface of a thin film of gold. This method yields gene amplification results in mere minutes, and promises to transform point-of-care diagnostics in fields as diverse as medicine, food security and evolutionary biology. (Image courtesy of Luke Lee’s BioPOETS lab)
turbocharged thermal cycling, described in a paper published July 31 in the journal Light: Science & Application, greatly expands the clinical and research applications of the polymerase chain reaction (PCR) test, with results ready in minutes instead of an hour or more.
The PCR test, which amplifies a single copy of a DNA sequence to produce thousands to millions of copies, has become vital in genomics applications, ranging from cloning research to forensic analysis to paternity tests. PCR is used in the early diagnosis of hereditary and infectious diseases, and for analysis of ancient DNA samples of mummies and mammoths.
The huge impact of the PCR test in modern science was recognized in 1993 with a Nobel Prize in Chemistry for its inventors, Kary Mullis and Michael Smith.
Using light-emitting diodes, or LEDs, the UC Berkeley researchers were able to heat electrons at the interface of thin films of gold and a DNA solution. They clocked the speed of heating the solution at around 55 degrees Fahrenheit per second. The rate of cooling was equally impressive, coming in at about 43.9 degrees per second.
“PCR is powerful, and it is widely used in many fields, but existing PCR systems are relatively slow,” said study senior author Luke Lee, a professor of bioengineering. “It is usually done in a lab because the conventional heater used for this test requires a lot of power and is expensive. Because it takes an hour or longer to complete each test, it is not practical for use for point-of-care diagnostics. Our system can generate results within minutes.”
The slowdown in conventional PCR tests comes from the time it takes to heat and cool the DNA solution. The PCR test requires repeated temperature changes – an average of 30 thermal cycles at three different temperatures – to amplify the genetic sequence, a process that involves breaking up the double-stranded DNA and binding the single strand with a matching primer. With each heating-cooling cycle, the amount of the DNA sample is doubled.
To pick up the pace of this thermal cycling, Lee and his team of researchers took advantage of plasmonics, or the interaction between light and free electrons on a metal’s surface. When exposed to light, the free electrons get excited and begin to oscillate, generating heat. Once the light is off, the oscillations and the heating stop.
Gold, it turns out, is a popular metal for this plasmonic photothermal heating because it is so efficient at absorbing light. It has the added benefit of being inert to biological systems, so it can be used in biomedical applications.
For their experiments, the researchers used thin films of gold that were 120 nanometers thick, or about the width of a rabies virus. The gold was deposited onto a plastic chip with microfluidic wells to hold the PCR mixture with the DNA sample.
The light source was an array of off-the-shelf LEDs positioned beneath the PCR wells. The peak wavelength of the blue LED light was 450 nanometers, tuned to get the most efficient light-to-heat conversion.
The researchers were able to cycle from 131 degrees to 203 degrees Fahrenheit 30 times in less than five minutes.
They tested the ability of the photonic PCR system to amplify a sample of DNA, and found that the results compared well with conventional PCR tests.
“This photonic PCR system is fast, sensitive and low-cost,” said Lee, who is also co-director of the Berkeley Sensor and Actuator Center. “It can be integrated into an ultrafast genomic diagnostic chip, which we are developing for practical use in the field. Because this technology yields point-of-care results, we can use this in a wide range of settings, from rural Africa to a hospital ER.”
Source: University of California – Berkeley.
Published on 31st July 2015