FY 1994 Annual Report to the Regents

Highlights from Natural and Physical Sciences, 1994

Paleontologist Philip Gingerich and colleagues recently reported the discovery of 46-million-year-old skeletal fossils of a mammal that walked on four legs on land, but swam with the up-and-down motion of a modern whale. Rodhocetus kasran was found in the mountains of Pakistan, a region once under a large ocean. This find is further evidence that the modern whale evolved from land mammals about 50 million years ago.

University of Michigan astronomers have discovered a line of clouds or "knots" of gas, strung out like pearls on a string, that extend more than halfway across the Crab Nebula. Gordon MacAlpine, professor of astronomy, and Stephen Lawrence, a UM graduate student in astronomy, discovered the knots while obtaining data for a three-dimensional model of the Crab Nebula. Understanding the mechanisms that produced the knots will help astronomers understand the unusual astrophysical processes and distribution of chemical elements in the nebula itself, according to MacAlpine. Spectral analysis of light from the knots shows them to be unlike anything ever seen before. Compared to surrounding filaments of gas, the knots show extremely high argon emissions.

A new UM study shows that the world's lakes have more carbon dioxide than they can use. Instead of soaking up atmospheric carbon dioxide, as many scientists believe, lakes are pumping carbon dioxide back into the atmosphere, reports George Kling, assistant professor of biology. Kling's analysis of data from 1,835 lakes found that nearly 90 percent of all lakes, whether in arctic, temperate or tropical areas, had carbon dioxide levels about three times greater than the surrounding atmosphere. His research is funded by the National Science Foundation and conducted with Jonathan Cole and Nina Caraco of the Institute of Ecosystem Studies and Timothy Kratz at the University of Wisconsin-Madison. The finding is significant, according to Kling, because it indicates land plants and soils may play an important role in regulating lake ecosystems. Understanding this lake-land relationship will be important as scientists struggle to predict the impact of global warming, says Kling.

A research group led by professor Duncan Steel of the departments of electrical engineering and computer science, physics, and the Institute of Gerontology has made a significant contribution to the fundamental physics of semiconductors. Also, this work will give a boost to the development of opto-electronic devices, such as light-emitting diodes, detectors, and lasers. Collaborating with a theory group from Arizona, Steel and his co-workers have shown that the previously-accepted theory explaining coherent nonlinear optical responses in certain types of semiconductors was incomplete. A new theory which they describe does a better job of explaining the interaction of light with the electrons in these semiconductors. A key experiment in Duncan's lab found that the opto-electronic behavior of these semiconductors is due to electron spin interactions, and not the static interactions invoked by the previous theory.

Radar mounted on the space shuttle Endeavour provided assistant research scientist Craig Dobson and his research team with detailed pictures of forests in Michigan's upper peninsula. His experiment, funded by NASA, assessed the ability of radar in the microwave range to count the number of trees and how big they are-the forest biomass-whether covered by snow or in full leaf. The high resolution color-coded images from the radar data are specific enough to tell spruce from pine and aspen from grasses. The first shuttle pictures were taken in April after a deep snowfall. A follow-up flight in August measured biomass, including the tree trunks, through the leaf cover. The ability to measure forest biomass is significant for determining the impact of plant life on global warming and climate change. More biomass information can be brought back to Earth aboard the shuttle than a satellite can reasonably transmit to the ground.

M-ROVER

Underwater exploration got a boost this year with the introduction of M-ROVER, a remotely operated vehicle. M-ROVER can manipulate and retrieve small objects or samples from lake bottoms, and is equipped with video and still cameras. This state-of-the-art vehicle, built by Benthos Underseas Systems, will be used in research, education, and underwater rescue, according to Guy Meadows, associate professor of atmospheric and oceanic sciences. The 500-pound M-ROVER operates on a long tether controlled from aboard the Laurentian, the UM research vessel. William Vorus, professor naval architecture and marine engineering, designed M-ROVER's propulsion system.

Adding finely ground shale to barrier walls appears to be an inexpensive and effective way to retard the spread of toxic contaminants from landfills and hazardous waste sites, according to Richard Gullick, a UM graduate student working with environmental engineering professor Walter Weber. His research, funded by the National Institutes of Environmental and Health Sciences, shows that shale may improve the ability of walls to prevent toxic substances from diffusing through the barriers into the ground water. Shale is inexpensive, readily available, easy to work with, should have long-term viability, and contains no harmful trace metals.