PROVIDENCE, R.I. [Brown University] — The public health community has long struggled with how best to reduce HIV infection rates among black Americans, which is seven times that of whites. In a new paper in the journal PLoS ONE, a team of physicians and public health researchers report that African-American clergy say they are ready to join the fight against the disease by focusing on HIV testing, treatment, and social justice, a strategy that is compatible with religious teaching.

“We in public health have done a poor job of engaging African-American community leaders and particularly black clergy members in HIV prevention,” said Amy Nunn, lead author of the study and assistant professor of medicine in the Warren Alpert Medical School of Brown University. “There is a common misperception that African American churches are unwilling to address the AIDS epidemic. This paper highlights some of the historical barriers to effectively engaging African American clergy in HIV prevention and provides recommendations from clergy for how to move forward.”

The paper analyzes and distills dozens of interviews and focus group data among 38 African-Amereican pastors and imams in Philadelphia, where racial disparities in HIV infection are especially stark. Seven in 10 new infections in the city are among black residents. With uniquely deep influence in their communities, nearly all of the 27 male and 11 female clergy said they could and would preach and promote HIV testing and treatment.

That message, delivered by clergy or other influential figures, would provide a needed complement to decades of public health efforts that have emphasized risk behaviors, Nunn said. Research published and widely reported last year, for example, suggests that testing and then maintaining people on treatment could dramatically reduce new infections because treatment can give people a 96-percent lower chance of transmitting HIV.

“For decades, we’ve focused many HIV prevention efforts on reducing risky behavior,” said Nunn, who is also based at The Miriam Hospital. “Focusing on HIV testing and treatment should be the backbone of HIV prevention strategies and efforts to reduce racial disparities in HIV infection. Making HIV testing routine is the gateway to getting more individuals on treatment. African American clergy have an important role to play in routinizing HIV testing.”

The barriers clergy members face

Many religious leaders acknowledged that they’ve struggled with how best to combat the epidemic, particularly with challenges related to discussing human sexuality in church or mosque, according to the analysis in the paper.

“One time my pastor spoke to young people about sex, mentioning using protection,” the paper quotes a clergy member as saying in one example. “I was sitting in the clergy row; you could feel the heat! I was surprised he said that. Comments from the clergy highlighted they were opposed to that. It’s a tightrope walk.”

Many clergy members also said they face significant barriers to preaching about risk behaviors without still emphasizing abstinence.

“It’s my duty as a preacher to tell people to abstain,” one pastor told the research team, “but if they’re still having sex and they’re getting HIV, there has to be another way to handle this.”

What clergy can do

Many clergy members suggested couching the HIV/AIDS epidemic in social justice rather than behavioral terms, Nunn said. They also recommended focusing on HIV testing as an important means to help stem the spread of the disease and reduce the stigma.

“We need to standardize testing,” one pastor told the researchers. “One thing that we could do immediately is to encourage our congregations — everybody — to get tested. … We’re not dealing with risk factors. And we’re all going to get tested once a year. That’s the one thing that we could do that doesn’t get into our doctrine about sexuality.”

In general, many of the religious leaders said they could encourage discussion of HIV not only in main worship services, but also in ministries and community outreach activities.

The streets of Philadelphia

Nunn and collaborators have already begun such work in the city. In 2010, for example, she worked with prominent pastors, local media companies and Mayor Nutter’s office of faith-based initiatives to promote and destigmatize HIV testing across the city. This year, in partnership with dozens of churches and other community leaders, she will oversee an HIV prevention campaign that includes door-to-door testing in an entire zip code of Philadelphia with high infection rates.

“Religious leaders are, in fact, willing to engage in dialogue and HIV prevention if you do it in a culturally appropriate and faith-friendly way,” Nunn said. “This means that HIV prevention should be couched in social justice and public health rather than in exclusively behavioral terms. HIV testing should be the backbone of any strategy to engage African American clergy in HIV prevention.”

In addition to Nunn, the paper’s other authors are Michelle Lally and Tim Flanigan of Brown and The Miriam, Alexandra Cornwall of The Miriam, former Brown students Nora Chute and Julia Sanders, Gladys Thomas and Stacey Trooskin of the University Pennsylvania, and George James of the Council for Relationships.

– By David Orenstein

*Source: Brown University

They performed advanced statistical analysis on two different North American regional climate models and were able to estimate projections of temperature changes for the years 2041 to 2070, as well as the certainty of those projections.

The analysis, developed by statisticians at Ohio State University, examines groups of regional climate models, finds the commonalities between them, and determines how much weight each individual climate projection should get in a consensus climate estimate.

For the first time, researchers have been able to build a consensus between different regional climate models using spatial statistics. In this image (above), the color red indicates regions of North America for which the statistical analysis indicates a 97.5 percent probability that average temperatures will rise by at least 2 degrees Celsius (3.6 degrees Fahrenheit) by 2070. Image by Noel Cressie and Emily Kang, courtesy of Ohio State University.

Through maps on the statisticians’ website, people can see how their own region’s temperature will likely change by 2070 – overall, and for individual seasons of the year.

Given the complexity and variety of climate models produced by different research groups around the world, there is a need for a tool that can analyze groups of them together, explained Noel Cressie, professor of statistics and director of Ohio State’s Program in Spatial Statistics and Environmental Statistics.

Cressie and former graduate student Emily Kang, now at the University of Cincinnati, present the statistical analysis in a paper published in the International Journal of Applied Earth Observation and Geoinformation.

“One of the criticisms from climate-change skeptics is that different climate models give different results, so they argue that they don’t know what to believe,” he said. “We wanted to develop a way to determine the likelihood of different outcomes, and combine them into a consensus climate projection. We show that there are shared conclusions upon which scientists can agree with some certainty, and we are able to statistically quantify that certainty.”

For their initial analysis, Cressie and Kang chose to combine two regional climate models developed for the North American Regional Climate Change Assessment Program. Though the models produced a wide variety of climate variables, the researchers focused on temperatures during a 100-year period: first, the climate models’ temperature values from 1971 to 2000, and then the climate models’ temperature values projected for 2041 to 2070. The data were broken down into blocks of area 50 kilometers (about 30 miles) on a side, throughout North America.

Statisticians at Ohio State University and the University of Cincinnati used spatial statistics and different regional climate models to build a consensus of likely temperature changes across North America. In this image, the color intensity corresponds to the temperature change expected by 2070, measured in degrees Celsius. The greatest temperature increases occur in the north, particularly in the Hudson Bay. Image by Noel Cressie and Emily Kang, courtesy of Ohio State University.

Averaging the results over those individual blocks, Cressie and Kang’s statistical analysis estimated that average land temperatures across North America will rise around 2.5 degrees Celsius (4.5 degrees Fahrenheit) by 2070. That result is in agreement with the findings of the United Nations Intergovernmental Panel on Climate Change, which suggest that under the same emissions scenario as used by NARCCAP, global average temperatures will rise 2.4 degrees Celsius (4.3 degrees Fahrenheit) by 2070. Cressie and Kang’s analysis is for North America – and not only estimates average land temperature rise, but regional temperature rise for all four seasons of the year.

Cressie cautioned that this first study is based on a combination of a small number of models. Nevertheless, he continued, the statistical computations are scalable to a larger number of models. The study shows that climate models can indeed be combined to achieve consensus, and the certainty of that consensus can be quantified.

The statistical analysis could be used to combine climate models from any region in the world, though, he added, it would require an expert spatial statistician to modify the analysis for other settings.

The key is a special combination of statistical analysis methods that Cressie pioneered, which use spatial statistical models in what researchers call Bayesian hierarchical statistical analyses.

The latter techniques come from Bayesian statistics, which allows researchers to quantify the certainty associated with any particular model outcome. All data sources and models are more or less certain, Cressie explained, and it is the quantification of these certainties that are the building blocks of a Bayesian analysis.

Noel Cressie. Image credit: Ohio State University

In the case of the two North American regional climate models, his Bayesian analysis technique was able to give a range of possible temperature changes that includes the true temperature change with 95 percent probability.

After producing average maps for all of North America, the researchers took their analysis a step further and examined temperature changes for the four seasons. On their website, they show those seasonal changes for regions in the Hudson Bay, the Great Lakes, the Midwest, and the Rocky Mountains.

In the future, the region in the Hudson Bay will likely experience larger temperature swings than the others, they found.

That Canadian region in the northeast part of the continent is likely to experience the biggest change over the winter months, with temperatures estimated to rise an average of about 6 degrees Celsius (10.7 degrees Fahrenheit) – possibly because ice reflects less energy away from the Earth’s surface as it melts. Hudson Bay summers, on the other hand, are estimated to experience only an increase of about 1.2 degrees Celsius (2.1 degrees Fahrenheit).

According to the researchers’ statistical analysis, the Midwest and Great Lakes regions will experience a rise in temperature of about 2.8 degrees Celsius (5 degrees Fahrenheit), regardless of season. The Rocky Mountains region shows greater projected increases in the summer (about 3.5 degrees Celsius, or 6.3 degrees Fahrenheit) than in the winter (about 2.3 degrees Celsius, or 4.1 degrees Fahrenheit).

In the future, the researchers could consider other climate variables in their analysis, such as precipitation.

This research was supported by NASA’s Earth Science Technology Office. The North American Regional Climate Change Assessment Program is funded by the National Science Foundation, the U.S. Department of Energy, the National Oceanic and Atmospheric Administration, and the U.S. Environmental Protection Agency office of Research and Development.

- Written by Pam Frost Gorder

*Source: The Ohio State University

UMD and JQI scientist Ranojoy Bose, says their new optical switch is not quite an optical transistor yet, but that their new results — which will be published in an upcoming issue of the journal Physical Review Letters
— represent a great start toward creating a usable ultrafast, low-energy on-chip signal router. “Our paper shows that switching can be achieved physically by using only 6 photons of energy, which is completely unprecedented. This is the achievement of fundamental physical milestonessub-100-aJ switching and switching near the single photon level,” Bose says

Why, aren’t electrons good enough? Well, nothing travels faster than light, and in the effort to speed up the processing and transmission of information, the combined use of light parcels (photons) along with electricity parcels (electrons) is desirable for developing a workable opto-electronic approach.

Setup of a waveguide made from a photonic crystal. Image credit: Ranojoy Bose

Information Gateways

The transistor is a solid-state component in which a gate signal is applied to a nearby tiny conducting pathway, thus switching on and off the passage of an information signal. The analogous process in photonics would be a solid-state component which acts as a gate, enabling or disabling the passage of light through a nearby waveguide, or as a router, for switching beams in different directions.

The JQI researchers — led by UMD’s Edo Waks, an assistant professor of electrical and computer engineering and JOI fellow — created their all-optical switch using a quantum dot (the equivalent of a gate) placed inside a resonant cavity. The dot, consisting of a nm-sized sandwich of the elements indium and arsenic, is so tiny that electrons moving inside can emit light at only discrete wavelengths, as if the dot were an atom. The quantum dot sits inside a photonic crystal, a material that has been bored with many tiny holes. The holes preclude the passage of light through the crystal except for a narrow wavelength range.

Actually, the dot sits inside a small hole-free arcade which acts like a resonant cavity. When light travels down the nearby waveguide some of it makes its way into the cavity, where it interacts with the quantum dot. And it is this interaction which can transform the waveguide’s transmission properties. Although 140 photons are needed in the waveguide to produce switching action, only about 6 photons actually are needed to bring about modulation of the QD, thus throwing the switch.

The switch in action. Image credit: Ranojoy Bose

Previous optical switches have been able to work only by using bulky nonlinear-crystals and high input power. The JQI switch, by contrast, achieves high-nonlinear interactions using a single quantum dot and very low power input. Switching required only 90 aJ of power, some five times less than the best previous reported device made at labs in Japan (***), which itself used 100 times less power than other all-optical switches. The Japanese switch, however, has the advantage of operating at room temperature, while the JQI switch requires a temperature of around 40 K.

So, why is this quantum-dot switch not the full equivalent of an “optical transistor”? “Our waveguide-dot setup can’t yet be used to modulate a beam of light using only a weak control pulse of light—what we would call a low-photon-number pulse,” says Bose.

But Bose says he expects an improvement (reduction) in the number of photons needed to switch the resonant cavity on and off.
Already, the JQI (*) switch can steer a beam of light from one direction to another in only 120 picoseconds (120 trillionths of a second), requiring very little power, only about 90 attojoules (90 x 10-18 joules). At the wavelength used, in the near infrared (921 nm), this amounts to about 140 photons.

(*)The Joint Quantum Institute is operated jointly by the National Institute of Standards and Technology in Gaithersburg, MD and the University of Maryland in College Park.

(**) “Low photon number optical switching with a single quantum dot coupled to a photonic crystal cavity,”
Deepak Sridharan, Ranojoy Bose, Hyochul Kim, Glenn S. Solomon, and Edo Waks. Physical Review Letters, in press.

(***) Nozaki et al., Nature Photonics, 2 May 2010.

*Source: University of Maryland

Tom Sharkey, chairperson of the Michigan State University biochemistry and molecular biology department, believes isoprene, a gas given off by many trees, ferns and mosses, could be a viable option. Some plants use it as a mechanism to tolerate heat stress as opposed to most crops, which stay cool through evaporation.

Tom Sharkey, chairperson of MSU's biochemistry and molecular biology department, has developed a method to produce bio-isoprene, which could lead to eco-friendly tires. Photo by G.L. Kohuth

Sharkey’s research team already has measured rates of isoprene emission from plants that are used by the Environmental Protection Agency to predict lower-atmosphere ozone levels. His team also has created models to measure how much isoprene plants release on a global scale. Given the amounts of isoprene made by plants, finding a way to produce a synthetic version for the rubber industry seemed like the next logical step, Sharkey said.

“I’ve found that isoprene research is irresistible,” he said. “Once it was clear how much isoprene trees and plants produce and how biologically produced isoprene could be a key ingredient in making tires, it was natural to wonder if we could produce isoprene on a commercial scale.”

The majority of automobile tires are made of natural rubber from latex-bearing trees. Harvesting rubber from these trees to feed the world’s appetite for tires isn’t sustainable, Sharkey added. Since rubber is made up of isoprene, Sharkey has worked to create a manmade version, bio-isoprene, which can serve as an eco-friendly alternative source for synthetic rubber production.

Other researchers have made isoprene from petroleum to make synthetic rubber. Sharkey’s team, however, is working to produce bio-isoprene using an enzyme he has cloned. With the enzyme, Sharkey has made bio-isoprene using bacteria. Sharkey and his team have partnered with private companies to scale up his research. Ultimately, he hopes this innovative process would take in carbon dioxide and discharge bio-isoprene using only sunlight as an energy source.

“Rubber prices are rising, and the competition for developing synthetic rubber is heating up,” Sharkey said. “This should help lead to effective ways to engineer bio-isoprene and ultimately keep costs low using this renewable alternative source for rubber production.”

Sharkey’s research, which is funded in part by the National Science Foundation, is featured in the current issue of International Innovation.

*Source: Michigan State University

Richard E. Tremblay (Picture: Jean-François Hamelin)

The researchers took saliva samples from 314 pairs of twins and measured the levels of testosterone. They then compared the similarity in testosterone levels between identical and fraternal twins to determine the contribution of genetic and environmental factors. Results indicated that differences in levels of testosterone were due mainly to environmental factors. “The study was not designed to specifically identify these environmental factors which could include a variety of environmental conditions, such as maternal diet, maternal smoking, breastfeeding and parent-child interactions.”

“Because our study suggests that testosterone levels in infants are determined by the circumstances in which the child develops before and after birth, further studies will be needed to find out exactly what these influencing factors are and to what extent they change from birth to puberty,” Tremblay said.

About this study:

The article Genetic and environmental contributions to saliva testosterone levels in male and female infant twins was published in an advanced, online edition of Psychoneuroendocrinology on May 7, 2012, by Dr. Richard E Tremblay of the University of Montreal’s Research Unit on Children’s Psychosocial Maladjustment. Dr Tremblay is also affiliated with the university’s departments of pediatrics, psychiatry and psychology and with University College Dublin in Ireland. The research received funding from the Canadian Institutes of Health Research, the Social Sciences and Humanities Research Council of Canada, the Fonds de la recherche du Québec. The University of Montreal is officially known as Université de Montréal.

*Source: Université de Montréal

“The preliminary results of our study suggest that people are more likely to disclose sensitive information via text messages than in voice interviews,” said Fred Conrad, a cognitive psychologist and director of the Program in Survey Methodology at the University of Michigan Institute for Social Research.

Image credit: University of Michigan

“This is sort of surprising since many people thought that texting would decrease the likelihood of disclosing sensitive information because it creates a persistent, visual record of questions and answers that others might see on your phone and in the cloud.”

With text, the researchers also found that people were less likely to engage in “satisficing”—a survey industry term referring to the common practice of giving good enough, easy answers, like rounding to multiples of 10 in numerical responses, for example.

“We believe people give more precise answers via texting because there’s just not the time pressure in a largely asynchronous mode like text that there is in phone interviews,” Conrad said. “As a result, respondents are able to take longer to arrive at more accurate answers.”

Conrad conducted the study with Michael Schober, a professor psychology and dean of the graduate faculty at The New School for Social Research. Their research team included cognitive psychologists, psycholinguists, survey methodologists and computer scientists from both universities, as well as collaborators from AT&T Research. Funding for the study came from the National Science Foundation.

Image credit: University of Michigan

“We’re in the early stages of analyzing our findings,” Schober said. “But so far it seems that texting may reduce some respondents’ tendency to shade the truth or to present themselves in the best possible light in an interview—even when they know it’s a human interviewer they are communicating with via text. What we cannot yet be sure of is who is most likely to be disclosive in text. Is it different for frequent texters, or generational, for example?”

For the study, the researchers recruited approximately 600 iPhone-users on Craigslist, through Google Ads, and from Amazon’s Mechanical Turk, offering them iTunes Store incentives to participate in the study. Their goals were to see whether responses to the same questions differed depending on several variables: whether the questions were asked via text or voice, whether a human or a computer asked the questions, and whether the environment, including the presence of other people and the likelihood of multitasking, affected the answers.

Among the questions that respondents answered more honestly via text than speech: In a typical week, about how often do you exercise? During the past 30 days, on how many days did you have five or more drinks on the same occasion?

And among the questions that respondents answered more precisely via text, providing fewer rounded numerical responses: During the last month, how many movies did you watch in any medium? How many songs do you currently have on your iPhone?

According to Conrad and Schober, changes in communication patterns and their impact on the survey industry prompted the study. About one in five U.S. households only use cell phones and no longer have landline phones. These households are typically not surveyed even though cell-only households tend to differ in important ways from households with landline phones. More people are using text messages on mobile phones, with texting now the preferred form of communication among many people in their teens and 20s in the United States. Texting is extremely common among all age groups in many Asian and European nations.

Conrad and Schober are also finding that people are more likely to provide thoughtful and honest responses via text messages even when they’re in busy, distracting environments.

“This is the case even though people are more likely to be multitasking—shopping or walking, for example—when they’re answering questions by text than when they’re being interviewed by voice,” Conrad said.

- Written by Diane Swanbrow

*Source: University of Michigan (Published on May 16, 2012)

Everyone does signal processing every day, even if we don’t call it that. With friends at a sports bar, we peer up at the TV to see the score, we turn our head toward the crashing sound when a waitress drops a glass, and perhaps most remarkably, we can track the fast-paced banter of all the people in our booth, even if we’ve never met some of the friends-of-friends who have insinuated themselves into the scene.

Very few of us, however, could ever get a computer to do anything like that. That’s why doing it well has earned Brian Reggiannini a Ph.D. at Brown and a career in the industry.

In his dissertation, Reggiannini managed to raise the bar for how well a computer connected to a roomful of microphones can keep track of who among a small group of speakers is talking. Further refined and combined with speech recognition, such a system could lead to instantaneous transcriptions of meetings, courtroom proceedings, or debates among, say, several rude political candidates who are prone to interrupt. It could help the deaf follow conversations in real-time.

If only it weren’t so hard to do.

But Reggiannini, who came to Brown as an undergraduate in 2003 and began building microphone arrays in the lab of Harvey Silverman, professor of engineering, in his junior year, was determined to advance the state of the art.

Real-time tracking of who’s talking. With the right algorithms and signal processing software, an array of button-size microphones placed around the perimeter of a room can identify, follow, and record each of several people as they move about, interrupt each other, and converse. Image credit: Frank Mullin/Brown University

The specific challenge he set for himself was real-time tracking of who’s talking among at least a few people who are free to rove around a room. Hardware was not the issue. The test room on campus has 448 microphones all around the walls and he only used 96. That was enough to gather the kind of information that allows systems – think of your two ears – to locate the source of a sound.

The real rub was in devising the algorithms and, more abstractly, in realizing where his reasoning about the problem had to abandon the conventional wisdom.

Previous engineers who had tried something like this were on the right track. After all, there is only so much data available in situations like this. Some tried analyzing accents, pronunciation, word use, and cadence, but those are complex to track and require a lot of data. The simpler features are pitch, volume, and spectral statistics (a breakdown of a voice’s component waves and frequencies) of each speaker’s voice. Systems can also ascertain where a voice came from within the room.

Snippets, not speakers

But many attempts to build speaker identification systems (like the voice recognition in your personal computer) have relied on the idea that a computer could be extensively trained in “clean,” quiet conditions to learn a speaker’s voice in advance.

One of Reggiannini’s key insights was that just like a politician couldn’t possibly be primed to recognize every voter at a rally, it’s unrealistic to train a speaker-recognition system with the voice of everyone who could conceivably walk into a room.

Brian Reggiannini. “We’re trying to teach a computer how to do something that we as humans do so naturally that we don’t even understand how we do it.” Image credit: Brown University

Instead, Reggiannini sought to build a system that could learn to distinguish the voices of anyone within a session. It analyzes each new segment of speech and also notes the distinct physical position of individuals within the room. The system compares each new segment, or snippet, of what it hears to previous snippets. It then determines a statistical likelihood that the new snippet would have come from a speaker it has already identified as unique.

“Instead of modeling talkers, I’m going to instead model pairs of speech segments,” Reggiannini recalled.

A key characteristic of Reggiannini’s system is that it can work with very short snippets of speech. It doesn’t need full sentences to work at least somewhat well. That’s important because it’s realistic. People don’t speak in florid monologues. They speak in fractured conversations. No way! Yes, really.

People also are known to move around. For that reason position as inferred by the array of microphones can be only an intermittent asset. At any single moment in time, especially at the beginning of a session, position helpfully distinguishes each talker from every other (no two people can be in the same place at the same time), but when people stop talking and start walking, the system necessarily loses track of them until they speak again.

Reggiannini tested his system every step of the way. His experiments included just pitch analysis, just spectral analysis, a combination of the two, position alone, and a combination of the full speech analysis and position tracking. He subjected the system to a multitude of voices, sometimes male-only, sometimes female-only, and sometimes mixed. In every case, at least until the speech snippets became quite long, his system was better able to discriminate among talkers than two other standard approaches.

That said, the system sometimes is uncertain and in cases like that it defers assigning speech to a talker until it is more certain. Once it is, it goes back and labels the snippets accordingly.

It’s no surprise that the system would err, or hedge, here and there. Reggiannini’s test room was noisy. While some systems are fed very clean audio, the only major concessions that Reggiannini allowed himself were that speakers wouldn’t run or jump across the room and that only one would speak from the script at a time. The ability to filter individual voices out from within overlapping speech is perhaps the biggest remaining barrier between the system remaining a research project and becoming a commercial success.

A career in the field

While the ultimate fate of Reggiannini’s innovations is not yet clear, what is certain is that he has been able to embark on a career in the field he loves. Since leaving Brown last summer he’s been working as a digital signal processing engineer at Analog Devices in Norwood, Mass., which happens to be his hometown.

Reggiannini has yet to work on an audio project, but that’s fine with him. His interest is the signal processing, not sound per se. Instead he’s applied his expertise to challenges of heart monitoring and wireless communications.

“I’ve been jumping around applications but all the fundamental signal processing theory applies no matter what the signal is,” he said. “My background lets me work on a wide range of problems.”

After seven years and three degrees at Brown, Reggiannini was prepared to pursue his passion.

- By David Orenstein

*Source: Brown University

Imagine charging your phone as you walk, thanks to a paper-thin generator embedded in the sole of your shoe. This futuristic scenario is now a little closer to reality. Scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed a way to generate power using harmless viruses that convert mechanical energy into electricity.

The scientists tested their approach by creating a generator that produces enough current to operate a small liquid-crystal display. It works by tapping a finger on a postage stamp-sized electrode coated with specially engineered viruses. The viruses convert the force of the tap into an electric charge.

Their generator is the first to produce electricity by harnessing the piezoelectric properties of a biological material. Piezoelectricity is the accumulation of a charge in a solid in response to mechanical stress.

The first part of the video shows how Berkeley Lab scientists harness the piezoelectric properties of a virus to convert the force of a finger tap into electricity. The second part shows the “viral-electric” generators in action, first by pressing only one of the generators, then by pressing two at the same time, which produces more current. Video by Seung-Wuk Lee’s lab

The milestone could lead to tiny devices that harvest electrical energy from the vibrations of everyday tasks such as shutting a door or climbing stairs.

It also points to a simpler way to make microelectronic devices. That’s because the viruses arrange themselves into an orderly film that enables the generator to work. Self-assembly is a much sought after goal in the finicky world of nanotechnology.

The scientists describe their work in a May 13 advance online publication of the journal Nature Nanotechnology.

Photo by Roy Kaltschmidt of Berkeley Lab

“More research is needed, but our work is a promising first step toward the development of personal power generators, actuators for use in nano-devices, and other devices based on viral electronics,” says Seung-Wuk Lee, a faculty scientist in Berkeley Lab’s Physical Biosciences Division and a UC Berkeley associate professor of bioengineering.

He conducted the research with a team that includes Ramamoorthy Ramesh, a scientist in Berkeley Lab’s Materials Sciences Division and a professor of materials sciences, engineering, and physics at UC Berkeley; and Byung Yang Lee of Berkeley Lab’s Physical Biosciences Division.

The piezoelectric effect was discovered in 1880 and has since been found in crystals, ceramics, bone, proteins, and DNA. It’s also been put to use. Electric cigarette lighters and scanning probe microscopes couldn’t work without it, to name a few applications.

But the materials used to make piezoelectric devices are toxic and very difficult to work with, which limits the widespread use of the technology.

The M13 bacteriophage has a length of 880 nanometers and a diameter of 6.6 nanometers. It’s coated with approximately 2700 charged proteins that enable scientists to use the virus as a piezoelectric nanofiber. Image courtesy of Seung-Wuk Lee's lab

Lee and colleagues wondered if a virus studied in labs worldwide offered a better way. The M13 bacteriophage only attacks bacteria and is benign to people. Being a virus, it replicates itself by the millions within hours, so there’s always a steady supply. It’s easy to genetically engineer. And large numbers of the rod-shaped viruses naturally orient themselves into well-ordered films, much the way that chopsticks align themselves in a box.

These are the traits that scientists look for in a nano building block. But the Berkeley Lab researchers first had to determine if the M13 virus is piezoelectric. Lee turned to Ramesh, an expert in studying the electrical properties of thin films at the nanoscale. They applied an electrical field to a film of M13 viruses and watched what happened using a special microscope. Helical proteins that coat the viruses twisted and turned in response—a sure sign of the piezoelectric effect at work.

Next, the scientists increased the virus’s piezoelectric strength. They used genetic engineering to add four negatively charged amino acid residues to one end of the helical proteins that coat the virus. These residues increase the charge difference between the proteins’ positive and negative ends, which boosts the voltage of the virus.

The scientists further enhanced the system by stacking films composed of single layers of the virus on top of each other. They found that a stack about 20 layers thick exhibited the strongest piezoelectric effect.

The bottom 3-D atomic force microscopy image shows how the viruses align themselves side-by-side in a film. The top image maps the film's structure-dependent piezoelectric properties, with higher voltages a lighter color. Image courtesy of Seung-Wuk Lee's lab

The only thing remaining to do was a demonstration test, so the scientists fabricated a virus-based piezoelectric energy generator. They created the conditions for genetically engineered viruses to spontaneously organize into a multilayered film that measures about one square centimeter. This film was then sandwiched between two gold-plated electrodes, which were connected by wires to a liquid-crystal display.

When pressure is applied to the generator, it produces up to six nanoamperes of current and 400 millivolts of potential. That’s enough current to flash the number “1” on the display, and about a quarter the voltage of a triple A battery.

“We’re now working on ways to improve on this proof-of-principle demonstration,” says Lee. “Because the tools of biotechnology enable large-scale production of genetically modified viruses, piezoelectric materials based on viruses could offer a simple route to novel microelectronics in the future.”

From left, Byung Yang Lee, Seung-Wuk Lee, and Ramamoorthy Ramesh developed the "viral-electric" generator. Photo by Roy Kaltschmidt of Berkeley Lab

Berkeley Lab’s Laboratory Directed Research and Development fund and the National Science Foundation supported this work.

– By Dan Krotz

*Source: Berkeley Lab

RESTON, VA, May 18, 2012 – comScore, Inc., a leader in measuring the digital world, today released data from the comScore Video Metrix service showing that 181 million U.S. Internet users watched nearly 37 billion online content videos in April. Video ads saw another record-breaking month with nearly 9.5 billion, representing 1 in 5 videos viewed online in April.

Top 10 Video Content Properties by Unique Viewers

Google Sites, driven primarily by video viewing at YouTube.com, ranked as the top online video content property in April with 157.7 million unique viewers, followed by Yahoo! Sites with 53.6 million, VEVO with 49.5 million, Facebook.com with 44.3 million and Microsoft Sites with 42.8 million. Nearly 37 billion video views occurred during the month, with Google Sites generating the highest number at 17 billion, followed by Hulu with 901 million and Yahoo! Sites with 742 million. The average viewer watched 21.8 hours of online video content, with Google Sites (7.2 hours) and Hulu (3.8 hours) earning the highest average engagement among the top ten properties.

*A video is defined as any streamed segment of audiovisual content, including both progressive downloads and live streams. For long-form, segmented content, (e.g. television episodes with ad pods in the middle) each segment of the content is counted as a distinct video stream.

Top 10 Video Ad Properties by Video Ads Viewed

Americans viewed 9.5 billion video ads in April, representing another month of record video ad views. Hulu topped the chart with 1.6 billion video ads delivered, followed by Google Sites with 1.3 billion, BrightRoll Video Network with 943 million, Adap.tv with 881 million and TubeMogul Video Ad Platform with 831 million. Time spent watching video ads totaled 3.9 billion minutes, with Hulu delivering the highest duration of video ads at 670 million minutes. Video ads reached 52 percent of the total U.S. population an average of 60 times during the month. Hulu delivered the highest frequency of video ads to its viewers with an average of 49, while ESPN delivered an average of 27 ads per viewer.

*Video ads include streaming-video advertising only and do not include other types of video monetization, such as overlays, branded players, matching banner ads, etc.
**Indicates video ad network
†Indicates video ad exchange

Top 10 YouTube Partner Channels by Unique Viewers

The April 2012 YouTube partner data revealed that video music channels VEVO (48.3 million viewers) and Warner Music (28.6 million viewers) maintained the top two positions. Gaming channel Machinima ranked third with 23.1 million viewers, followed by Maker Studios Inc. with 15.4 million, FullScreen with 12.3 million and BroadbandTV with 8.2 million. Among the top 10 YouTube partners, Machinima demonstrated the highest engagement (65 minutes per viewer) followed by VEVO (57 minutes per viewer). VEVO streamed the most videos (644 million), followed by Machinima (382 million).

*YouTube Partner Reporting based on online video content viewing and does not include claimed user-generated content

Other notable findings from April 2012 include:

• 84.5 percent of the U.S. Internet audience viewed online video.
• The duration of the average online content video was 6.4 minutes, while the average online video ad was 0.4 minutes.
• Video ads accounted for 20.5 percent of all videos viewed and 1.6 percent of all minutes spent viewing video online.

*Source: comScore

The turtle in question is Carbonemys cofrinii, which means “coal turtle,” and is part of a group of side-necked turtles known as pelomedusoides. The fossil was named Carbonemys because it was discovered in 2005 in a coal mine that was part of northern Colombia’s Cerrejon formation. The specimen’s skull measures 24 centimeters, roughly the size of a regulation NFL football. The shell which was recovered nearby – and is believed to belong to the same species – measures 172 centimeters, or about 5 feet 7 inches, long. That’s the same height as Edwin Cadena, the NC State doctoral student who discovered the fossil.

“We had recovered smaller turtle specimens from the site. But after spending about four days working on uncovering the shell, I realized that this particular turtle was the biggest anyone had found in this area for this time period – and it gave us the first evidence of giantism in freshwater turtles,” Cadena says.

Reconstruction of Carbonemys preying upon a small crocodylomorph. Artwork by Liz Bradford

Smaller relatives of Carbonemys existed alongside dinosaurs. But the giant version appeared five million years after the dinosaurs vanished, during a period when giant varieties of many different reptiles – including Titanoboa cerrejonensis, the largest snake ever discovered – lived in this part of South America. Researchers believe that a combination of changes in the ecosystem, including fewer predators, a larger habitat area, plentiful food supply and climate changes, worked together to allow these giant species to survive. Carbonemys’ habitat would have resembled a much warmer modern-day Orinoco or Amazon River delta.

In addition to the turtle’s huge size, the fossil also shows that this particular turtle had massive, powerful jaws that would have enabled the omnivore to eat anything nearby – from mollusks to smaller turtles or even crocodiles.

Thus far, only one specimen of this size has been recovered. Dr. Dan Ksepka, NC State paleontologist and research associate at the North Carolina Museum of Natural Sciences, believes that this is because a turtle of this size would need a large territory in order to obtain enough food to survive. “It’s like having one big snapping turtle living in the middle of a lake,” says Ksepka, co-author of the paper describing the find. “That turtle survives because it has eaten all of the major competitors for resources. We found many bite-marked shells at this site that show crocodilians preyed on side-necked turtles. None would have bothered an adult Carbonemys, though – in fact smaller crocs would have been easy prey for this behemoth.”

The paleontologists’ findings appear in the Journal of Systematic Palaeontology. Dr. Carlos Jaramillo from the Smithsonian Tropical Research Institute in Panama and Dr. Jonathan Bloch from the Florida Museum of Natural History contributed to the work. The research was funded by grants from the Smithsonian Institute and the National Science Foundation.

*Source: North Carolina State University