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May 13, 2015

In Research

Experiment on terahertz emission offers new approach

lens and a tiny dot of light
A microplasma is created by focusing intense laser pulses in air. Besides visible light, the microplasma emits electromagnetic pulses at terahertz frequencies that can be used to detect complex molecules, such as explosives and drugs.

Researchers at the Institute of Optics have shown that a laser-generated microplasma in air can be used as a source of broadband terahertz radiation.

In a paper published in Optica, Fabrizio Buccheri and Xi-Cheng Zhang demonstrate that an approach for generating terahertz waves using intense laser pulses in air—first pioneered in 1993—can be done with much lower power lasers, a major challenge until now. Doctoral student and lead author Buccheri says they exploited the underlying physics to reduce the necessary laser power for plasma generation. He says it could potentially be improved for applications in explosives or drug monitoring.

Applications for terahertz radiation, a form of electromagnetic radiation named after its frequency, can be divided into two categories: imaging and spectroscopy. Imaging using terahertz waves is similar to imaging using X-rays, but unlike X-rays it is not a form of ionizing radiation. Imaging with terahertz can, for example, allow us to look under layers of painting. For spectroscopy applications, “such as analyzing food for poisons or baggage for drugs or explosives it is useful for the terahertz radiation to be as ‘broadband’ as possible,” Buccheri says. That is, it contains waves of many different frequencies within the terahertz range. For this, a plasma is needed.

For common applications higher spectral resolution is not feasible—it costs more and requires sophisticated equipment. In those cases, more points of comparison are needed, just like in fingerprint analysis. The more points of comparison that are available, the more precise the analysis, and this is what a broadband source can provide, Buccheri says.


Parent training leads to gains for children with autism

Tantrums, aggression, self-injury and other serious behavior problems are common in children with autism spectrum disorder (ASD). In the largest-ever clinical trial for autism, a multisite study that included researchers at the Medical Center showed that a parent training program can help reduce those behaviors.

Results of the study, published in the Journal of the American Medical Association, show that parent training decreased serious behavior problems by 47.7 percent. Researchers compared the parent training with an education program that also reduced serious behavior problems, but not as much.

Given the increased recognition of ASD in children—1 in 68 children has been identified with ASD—there is a pressing need for effective and affordable treatments. The parent-training program in the study was designed to help meet the need. The program lasts 24 weeks and includes 11 core sessions in which a clinician works one-on-one with the primary caregiver for 60 to 90 minutes. There are also two home visits and up to four additional sessions.

“To provide this parent training, you need to be familiar with behavioral principles and children with autism, but you don’t need to be an autism specialist,” says Tristram Smith, professor of pediatrics who provides clinical services to children with ASD at Golisano Children’s Hospital.

The training program taught parents to identify environmental events that might contribute to behavior problems and presented strategies for preventing these problems. It also emphasized positive reinforcement for appropriate behavior and withholding reinforcement for inappropriate behavior.

”Parents often see their child’s behavior improve within a few weeks,” Smith said.

Smith was the lead investigator in Rochester. The other sites included Emory University, Indiana University, Ohio State University, University of Pittsburgh, and Yale University.


Study sheds new light on brain’s source of power

New research published in the journal Nature Communications represents a potentially fundamental shift in the understanding of how nerve cells in the brain generate the energy needed to function. The study shows neurons are more independent than previously believed. The research has implications for a range of neurological disorders.  

“These findings suggest that we need to rethink the way we look at brain metabolism,” says lead author Maiken Nedergaard, the Frank P. Smith Professor of Neurosurgery and codirector of the University of Rochester Center for Translational Neuromedicine.  “Neurons, and not the brain’s support cells, are the primary consumers of glucose and this consumption appears to correlate with brain activity.”

Unlike the rest of the body, the brain maintains its own unique ecosystem. Scientists have long believed that a support cell found in the brain, called the astrocyte, played an intermediary role in the supplying neurons with energy.

“Understanding the precise and complex biological mechanisms of the brain is a critical first step in disease-based research,” says Nedergaard. “Any misconception about biological functions—such as metabolism—will ultimately impact how scientists form hypothesize and analyze their findings. If we are looking in the wrong place, we won’t be able to find the right answers.”

Scientists have speculated that the astrocytes are the brain’s primary consumer of glucose and, like a mother bird that helps its chicks digest food, these cells convert the molecules to another derivative (lactate) before it is passed along to the neurons. Lactate is a form of sugar molecule that is used by mitochondria for fuel.

The new research, which was conducted in both mice and human brain cells, was possible due to new imaging technologies called 2-photon microscopy that enable scientists to observe activity in the brain in real time.


Study: Online ads drive sales

New research indicates that online advertisements can translate into better in-store and online sales for brick-and-mortar retailers. It also found that the effectiveness of online ads is especially high for a retailer’s most active customers and for those who live near the store’s physical location.

Garrett Johnson, assistant professor of marketing at Simon Business School, conducted the research with Randall Lewis and David Reiley from Yahoo! as an intern at Yahoo! Research.

The study tackles a classic problem in marketing: the effect of advertising on demand.

The team ran a controlled experiment examining two consecutive weeklong ad campaigns on Yahoo!. The campaigns, which targeted three-million consumers of a nationwide retailer, explored how online display advertising affects both online and in-store purchases.

“Our findings show just how much advertisers can learn, not only about the effectiveness of their ads, but how much this effectiveness varies between consumers segments,” says Johnson. “This experiment unveils a host of new insights for advertisers to better target their ads to consumer preferences and is one of the most statistically powerful experiments examining ad effectiveness.”


Grant supports work to restore vision

A team of Rochester researchers and their partners will receive $3.8 million from the National Eye Institute over the next five years as they design an optical system with the objective of accelerating the development of the next generation of cures for blindness.

“The new instrumentation we are developing builds on technology we had developed previously to improve vision through laser refractive surgery and contact lenses, as well as to diagnose retinal disease,” says Rochester’s principal investigator David Williams, the William G. Allyn Professor of Medical Optics and director of the Center for Visual Science. “This is the first time we have designed instrumentation specifically to develop and test therapies to restore vision in the blind.”

The National Eye Institute, part of the National Institutes of Health, announced the awards as part of its Audacious Goals Initiative to tackle the eye diseases that are most devastating and difficult to treat. The central goal is to restore vision by regenerating neurons and neural connections in the eye and visual system. The initiative places an emphasis on cells of the retina, including the light-sensitive rod and cone photoreceptors, and the retinal ganglion cells, which connect photoreceptors to the brain via the optic nerve.

“These ambitious projects will give us a window into the visual system,” says National Eye Institute Director Paul Sieving. “Tools developed will enhance the study of functional changes in the retina and optic nerve, in real-time and at the cellular level, and will be indispensable when evaluating new regenerative therapies for eye diseases.”

The imaging system being developed at Rochester builds on work pioneered by Williams, widely regarded as one of the world’s leading experts on human vision. He pioneered the use of adaptive optics technologies for vision applications.


Beijing Olympics study links pollution to birth weight

Chinese boy wearing face mask in smoggy city

Exposure to high levels of pollution can have a significant impact on fetal growth and development, according to School of Medicine and Dentistry researchers.

The study, which appeared in Environmental Health Perspectives, found that women who were pregnant during the 2008 Beijing Olympics, when pollution levels were reduced by the Chinese government, gave birth to children with higher birth weights compared to those who were pregnant before and after the games.

“The results of this study demonstrate a clear association between changes in air pollutant concentrations and birth weight,” says lead author David Rich, professor of public health sciences and of environmental medicine. “These findings not only illustrate one of the many significant health consequences of pollution, but also demonstrate that this phenomenon can be reversed.”

The researchers compiled information from 83,672 term births to mothers in four urban districts in Beijing. They compared birth weights for mothers whose eighth month of pregnancy occurred during the 2008 Olympics an Paralympics with those whose eighth month of pregnancy occurred at the same time of year in the years before (2007) and after (2009) the games when pollution levels were at their normally higher levels. They found that the babies born in 2008 were on average 23 grams larger than those in 2007 and 2009.

Late pregnancy is a particularly important period of fetal growth—the fetus experiences the greatest amount of physical growth, and the development of the central nervous, cardiovascular, and musculoskeletal systems accelerates. The study suggests that pollution may be interfering with the period of development.

While the biological mechanism by which pollution causes lower birth weights are not fully understood, the scientists speculate that several factors could play a role, including maternal inflammation, altered placental function, and reduced nutrient delivery to the fetus, which may impede fetal growth.


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