Stories of modern science ... from UPI

ENHANCED KINETIC ENERGY BOOSTS WARHEAD

The Navy is working to improve the effectiveness of its air defense warheads so they can destroy an incoming missile at a safe distance. The Office of Naval Research's new missile warheads enhance the kinetic energy -- energy an object has by virtue of its motion -- of inert fragments with chemical energy released when reactive fragments hit the target. Chemical energy is released as heat and pressure to increase the odds of destroying the target. The warhead fragments are composed of an advanced composite material made of powdered metal embedded in a plastic matrix that survives the explosive launch typical of warhead fragmentation. It promises potential lethality improvements of up to 500 percent.

MODELING LANDSCAPES FROM PHOTOS

Two Dartmouth professors have solved the problem of how to make accurate models of remote landscapes from photographs. Arjun Heimsath, assistant professor of Earth Sciences, and Hany Farid, assistant professor of Computer Science, create 3-D models of remote regions using two-dimensional digital photographs. They hope to use the new technique to predict landslides, erosion rates and other geomorphic events. Global positioning systems and satellites can create digital elevation models or DEMs, but are expensive, time consuming and unavailable in some remote areas. Farid says a single photograph does not have enough information to calculate the DEM but with at least three images of the same region, taken from different vantage points, you can capture all the necessary data. Once the images are in the computer, the researcher has to manually pick spots on each picture that correspond, such as identifying the same shrub. "After you pick somewhere between 50 and 100 points, the mathematical algorithm takes over and automatically estimates the elevation map," says Farid. The math algorithm used was developed for other applications and Farid and Heimsath modified it by adding constraints unique to the surface geometry of Earth's surface.

FASTER WAY TO FIND UNDERGROUND CONTAMINANTS

A new way to find underground contaminants, developed by University of Rhode Island geophysicist Reinhard Frohlich, can reduce drilling and digging beneath the surface, saving time and money. The process includes inserting two metal spikes in the ground at various distances and connecting them to an electric current. Frohlich says measuring the voltage between the spikes can determine the resistivity of the soil, which tells if the soil is polluted. Resistivity measurements calculate a material's opposition to the flow of electric current and are used to find contaminated salts dissolved in groundwater. Frohlich's experiments went farther, to find organic compounds like toluene, benzene, xylene, ethylbenzene, phenol and other cancer-causing substances that do not conduct electricity as easily as the salt. "Resistivity increases significantly in areas where the aquifer is polluted compared to clean areas," he said. "We should be able to use this as the first step in the remediation process because it's quicker and allows us to drill fewer borings into the aquifer."

RESEARCHERS DEVELOP MOUSE WITH JUMPING GENES

University of Pennsylvania researchers have bred a mouse to model human L1 retrotransposons -- so-called "jumping genes" -- small stretches of DNA copied from one location in the genome and inserted elsewhere. L1 retrotransposons are responsible for about one third of the human genome. The researchers hope this special mouse will add to their understanding of jumping genes and the role they play in the disease process. "There are about a half million L1 sequences in the human genome, of which 80 to 100 remain an active source of mutation," said Dr. Haig H. Kazazian Jr., chairman of the Department of Genetics and senior researcher. "This animal model will help us better understand how this happens, as well as provide a useful tool for discovering the function of known genes." In humans, retrotransposons cause mutations in important genes, leading to diseases such as hemophilia and muscular dystrophy.

---

(EDITORS: For more information on WARHEAD, contact John Petrik at 703-696-5031, or e-mail onrpao@onr.navy.mil. For DEM, Susan Knapp, 603-646-3661 or susan.knapp@dartmouth.edu, for RESISTIVITY, Todd McLeish 401-874-7892 or tmcleish@uri.edu, and for JUMPING GENES, Greg Lester, 215-349-5658 or gregory.lester@uphs.upenn.edu)