Applied Physics

In process that is shrouded in mystery, rod-shaped bacteria reproduce by splitting themselves in two. By applying advanced mathematics to laboratory data, a team led by Johns Hopkins researchers has solved a small but important part of this reproductive puzzle.

The findings apply to highly common rod-shaped bacteria such as E. coli, found in the human digestive tract. When these single-celled microbes set out to multiply, a signal from an unknown source causes a little-understood structure called a Z-ring to tighten like a rubber band around each bacterium’s midsection. The Z-ring pinches the rod-like body into two microbial sausages that finally split apart.

Biophysicists at the University of Pennsylvania have discovered that the nuclei of human stem cells are particularly soft and flexible, rather than hard, making it easier for stem cells to migrate through the body and to adopt different shapes, but ultimately to put human genes in the correct nuclear ¡°sector¡± for proper access and expression.

Researchers pulled cell nuclei into microscopic glass tubes under controlled pressures and visualized the shear of the DNA and associated proteins by fluorescence microscopy. The study showed that nuclei in human embryonic stem cells were the most deformable, followed by hematopoietic stem cells, HSCs, that generate a wide range of blood and tissue cells.

Natural gas ( methane ) has a greater global warming impact than carbon dioxide but conventional cellulose acetate membranes in processing plants lose natural gas in their waste products.

Thermally rearranged (TR) plastic works four times better than conventional membranes at separating out carbon dioxide, say University of Texas at Austin researchers. Dr. Ho Bum Park, a postdoctoral student in the laboratory of Professor Benny Freeman, also found that TR plastic membranes act quicker.

Verbs evolve and homogenize at a rate inversely proportional to their prevalence in the English language, according to a formula developed by Harvard University mathematicians who've invoked evolutionary principles to study our language over the past 1,200 years, from "Beowulf" to "Canterbury Tales" to "Harry Potter."

Writing this week in the journal Nature, Erez Lieberman, Jean-Baptiste Michel, and colleagues in Harvard's Program for Evolutionary Dynamics, led by Martin A. Nowak, conceive of linguistic development as an essentially evolutionary scheme: Just as genes and organisms undergo natural selection, words -- specifically, irregular verbs that do not take an "-ed" ending in the past tense -- are subject to powerful pressure to "regularize" as the language develops.

The ability to tactually recognize fine spatial details, such as the raised dots used in braille, is especially important to those who are blind. With that in mind, a team of researchers has identified the neural circuitry that facilitates spatial discrimination through touch. Understanding this circuitry may lead to the creation of sensory-substitution devices, such as tactile maps for the visually impaired.

The research team, led by Krish Sathian, MD, PhD, professor of neurology in Emory University School of Medicine, included first author Randall Stilla, research MRI technologist at Emory, and Gopikrishna Deshpande, Stephen Laconte and Xiaoping Hu of the Coulter Department of Biomedical Engineering at Georgia Tech and Emory.

A collaboration of University of Pennsylvania chemists and engineers has performed multi-scale modeling of ferroelectric domain walls and provided a new theory of behavior for domain-wall motion, the "sliding wall" that separates ferroelectric domains and makes high-density ferroelectric RAM (FeRAM) possible.

The new theory, supported by a novel modeling study developed specifically for this research, confirms experimental data long at odds with existing theories of domain-wall behavior. Most notable is that, Penn's simulations reproduced experimental domain growth rates and revealed small, square critical nuclei with a diffuse interface. Researchers also found that small dipoles play a key role in smoothing the transition between up and down regions as the wall moves.

Is using a Wii too much workout for you? Developers at the University of Washington may have something you like better. Designed for people with disabilities, their new software lets users control a computer cursor without any tactile involvement. Early tests suggest that an experienced user of Vocal Joystick would have as much control as someone using a handheld device.

"There are many people who have perfect use of their voice who don't have use of their hands and arms," said Jeffrey Bilmes, a UW associate professor of electrical engineering. "I think there are several reasons why Vocal Joystick might be a better approach, or at least a viable alternative, to brain-computer interfaces." The tool's latest developments will be presented this month in Tempe, Ariz.

Not literally aspirin, but researchers at the Boyce Thompson Institute for Plant Research (BTI) say methyl salicylate (MeSA), an aspirin-like compound, alerts a plant's immune system to shift into high gear.

It has long been known that plants often develop a state of heightened resistance, called systemic acquired resistance, following pathogen infection; this phenomenon requires the movement of a signal from the infected leaf to uninfected parts of the plant. Until now, however, no one knew what that signal was.

"Now that we have identified a signal that activates defenses throughout the plant, as well as the enzymes that regulate the level of this signal, we may be able to use genetic engineering to optimize a plant's ability to turn on those defenses," said Daniel F.

Evolution has mastered the art of turning trash to treasure - though, for scientists, witnessing the transformation can require a bit of patience. In new genetic research, scientists have traced the 170 million-year evolution of a piece of “junk” DNA to its modern incarnation as an important regulator of energy balance in mammals.

The discovery, they said, suggests that regions of the genome formerly presumed to be a genetic junkyard may actually be a hardware superstore, providing components that can be used to evolve new genes or new species.

Computer and behavioral scientists at the University at Buffalo say they are working on a system to compute a numerical score that determines the likelihood that someone is about to commit a terrorist act. Their technology will track faces, voices and other biometrics against scientifically tested behavioral indicators to provide that numerical score for an individual.

“The goal is to identify the perpetrator in a security setting before he or she has the chance to carry out the attack,” said Venu Govindaraju, Ph.D., professor of computer science and engineering at the University at Buffalo School of Engineering and Applied Sciences. Govindaraju is co-principal investigator on the project with Mark G.