|
|
|
|
|
|
|
|
|
|
|
|
| |
|
|
|
|
|||||||
| |
|
||||||||||
|
|
|
|
|
|
|
|
|||||
 |
 |
|
|
|
|
 |
 |
| |
|
|
|
|
|
Sarah Ades studies how one compartment of a cell knows what is going on in another compartment. Her research focuses on signal transduction between the two cellular compartments of Gram-negative bacteria: the cytoplasm and the cell envelope. The cell envelope plays an essential role for the bacterium by providing a barrier between the cell and the environment, determining its morphology and maintaining structural integrity. When a bacterium is stressed by a shock such as heat or an antibiotic chemical, the envelope can be damaged, which compromises the integrity of the bacterium. In order to survive, the cell mounts a response to repair the damage and this response is directed by the genetic machinery in the cytoplasm. Ades investigates the signal-transduction pathways that communicate information about damage in the cell envelope to proteins that regulate gene expression in the cytoplasm so that a response to repair the damage can be mounted. She is working on a known envelope-sensing pathway that is important for the virulence of several pathogenic bacteria and also is working to identify new pathways. She seeks to determine how these pathways are integrated into the cellular regulatory network, and to investigate in molecular detail how the interactions among members of a pathway result in signal transduction. "We want to know the mechanism of the cell's reaction to a fundamental change that affects its integrity," she says. "By disrupting the process, we can learn how it is held together. Once key pathways have been identified, we can then study their function on a cellular and molecular level during both the normal growth of the bacterium and during stresses such as antibiotic challenge." A second approach studies mutant strains with increased resistance or sensitivity to a drug in order to understand what factors allow the bacterium to tolerate—or be more susceptible to—damage in the cell envelope. In addition to contributions to the basic science of cell function, this work is expected to provide valuable insights into how antimicrobial drugs affect the cell and to lead to the identification of new targets for drug design. Ades earned her doctoral degree in biology at the Massachusetts Institute of Technology in 1995 and her bachelor's degree in molecular biophysics and biochemistry at Yale University in 1988. Prior to joining the Penn State faculty in June 2002, she was a postdoctoral fellow in the department of stomatology at the University of California in San Francisco from 1997 to 2002 and at the Institut de Biologie Moleculaire et Cellulaire in Strasbourg, France, from 1995 to 1997.
David Braun studies maize leaves as a model system to determine how groups of cells communicate and coordinate their development. He is studying mutations that are defective in chloroplast functions that affect only limited regions of a leaf. The goal of Braun’s research is to determine how and why portions of the leaf interpret and process information differently from others. The fact that the variations are regional, rather than cell by cell, suggests there is feedback communication between neighboring cells. “There are a number of interesting biological questions in this collection of mutants,” said Braun. “No one knows at the molecular level what signals are involved. It could be a function of classical signaling physiology, mobile RNA, or sugar thresholds.” Braun investigates the questions of cell function and fate with a genetic approach, using the mutants as tools to identify the malfunctioning gene, which he then studies at the cellular and molecular level. “If we can determine why it is broken and how it is broken, we can determine how the gene works when it functions correctly,” he said. “Because our screens utilize chloroplast pigmentation, there are a lot of data already in the public sector that can give clues to what is happening.” Although his research is not application driven, Braun's work is expected to provide a better understanding of signal transduction in leaf development, which would broaden the base of knowledge for applied plant science. Braun earned his doctorate in biological sciences at the University of Missouri in Columbia in 1997 and his bachelor’s degree in biology at the University of California in San Diego in 1991. Prior to joining the Penn State faculty in April 2003, he held a postdoctoral research position at the University of California in Berkeley from 1997 to 2003.
Nathanial Brown studies operator algebras, an area of mathematics in which the basic objects are infinite matrices rather than, say, numerical functions. The field has deep connections with physics, particularly quantum field theory and statistical mechanics. Over the past few decades, important and surprising connections have been discovered with other branches of mathematics, including geometry, probability, and topology. Brown's research interests involve fundamental questions in operator-algebra theory, so his work is geared toward the basic theoretical science rather than applied mathematics. Rather than the three familiar dimensions of space, Brown says, “An operator algebra is like a collection of infinite matrices that are impossible to visualize. Inside the matrix are numbers, but each matrix is infinite. They are subject to operations such as addition and multiplication just like any other matrix, but because they have infinite dimension, these mathematical operations are very complex.” However, some operator algebras can be approximated by finite-dimensional spaces. Brown's work has focused on “reducing” operator algebras to the finite-dimensional case in order to learn more about the infinite-dimensional object of interest. For example, he has developed a new notion of entropy—a measure of the disorder, or randomness, of a system—in which finite-dimensional approximations play a central role. Brown's current work focuses on the representation theory of operator algebras that builds on the earlier representation theory of groups. He is using approximation ideas to attack some basic questions in representation theory, including free probability and one of the fundamental problems in operator algebras, known as Elliott's classification program. Brown earned his doctorate in mathematics at Purdue University in 1999 and his bachelor's degree in mathematics at Lake Superior State University in 1993. Prior to joining the Penn State faculty in July 2002, he was a postdoctoral fellow at Michigan State University from 2001 to 2002, an assistant professor of mathematics at Central Michigan University from 2000 to 2001, a visiting assistant professor of mathematics at the University of California at Berkeley in 2000, and a visiting researcher at Institut Henri Poincare in Paris, France, in 1999.
Bernd Bruegmann specializes in numerical general relativity. "Einstein gave us his beautiful theory of general relativity in 1915, and it remains an almost perfect description of the gravitational interaction even by today's standards," Bruegmann said. "But a century later we are still trying to puzzle out how something as simple as the motion of two bodies works in detail." A key problem of numerical relativity is the binary-black-hole problem; that is, how two black holes orbit each other, spiral inward, and eventually merge to a single black hole. In 1999, Bruegmann published the results of a numerical simulation of a binary-black-hole merger, which was the first simulation of two orbiting black holes in general relativity. This research has matured into a major effort in large-scale simulations
for studying general relativity that encompass mathematical analysis of
the Einstein equations, numerical methods, super computing, and modeling
of astrophysical events. Bruegmann was part of a collaboration that computed
the gravitational waves generated during the collision of two black holes
after their last quasi-stable orbit. These calculations lay the theoretical
framework for interpretation of anticipated data about gravitational waves
from several large interferometric detectors now being A native of Germany, Bruegmann was an exchange student at Syracuse University in New York, where he earned his master's degree in mathematics in 1987 and his doctorate in physics in 1993. After postdoctoral fellowships in Germany at the Max Planck Institute for Physics and at the Max Planck Institute for Gravitational Physics, he joined the permanent research staff of the latter institute in 1997. Bruegmann joined the Penn State physics faculty in the summer of 2002. He is a member of Penn State’s Center for Gravitational Physics and Geometry.
Doug Cowen is an experimental particle astrophysicist who uses the Antarctic icecap to detect ultrahigh-energy cosmic neutrinos. Working with over 100 physicists from the United States, Belgium, Germany, Japan, Sweden, the Netherlands, and the United Kingdom, Cowen has helped build the world’s largest neutrino telescope at the South Pole, the Antarctic Muon and Neutrino Detector Array (AMANDA), and he is playing a leading role in the design and construction of AMANDA’s even larger kilometer-scale successor, IceCube. High-energy neutrinos are the only known particles that can emerge unscathed from the ultra-dense regions of the universe where they are created and accelerated—such as the vicinity of supermassive black holes or merging neutron stars. Because they also travel to Earth in a straight line, a device that could detect them would give astronomers a powerful tool that likely would open a vast new window on the heavens. “Snaring neutrinos is fiendishly difficult because they are extremely anti-social compared with other particles,” Cowen explains. “On the rare occasion when a neutrino does collide with ordinary matter, it spawns numerous energetic charged particles that emit radiation. This radiation can be detected as single photons by photomultiplier tubes—provided the collision occurs in a clear medium in which the light can travel relatively long distances before being scattered or absorbed.” The ice at the South Pole meets these criteria, according to Cowen, because it is 3 km thick and among the clearest and purest known natural substances. “To maximize the probability that an ultrahigh energy neutrino will pay us a visit, we take advantage of this vast resource that Mother Nature has provided and build our detector with gargantuan proportions—AMANDA occupies a volume ten times that of Beaver Stadium and IceCube a volume ten times larger still,” he says. To construct the detectors, Cowen and his collaborators use a hot-water drill to melt holes in the ice 60 cm wide and over two kilometers deep. Then they insert a string of photomultiplier tubes and allow the water to refreeze, repeating the process until their array of phototubes is large enough to allow them to reconstruct the signals created by neutrino interactions. “Although no ultrahigh-energy neutrino signals have yet been detected by AMANDA, we believe that with the enlarged IceCube detector our chances of discovering such a signal for the first time are very high.” Cowen earned his B.A. degree in physics, summa cum laude, at Dartmouth College in 1983 and his M.S. and Ph.D. degrees in physics at the University of Wisconsin in 1985 and 1990. He then was a postdoctoral fellow at the California Institute of Technology until 1994, working at Cornell University's Laboratory for Experimental Particle Physics, and an assistant professor of physics at the University of Pennsylvania until the fall of 2002, when he joined the Penn State faculty. His work is funded by the High Energy and Nuclear Physics divisions of the U. S. Department of Energy, by a National Science Foundation CAREER award, and by the National Aeronautics and Space Administration (NASA).
Michael Green uses theory and experiment to investigate the factors that determine enzyme reactivity. One area of focus is an unusual group of enzymes that catalyze the insertion of an oxygen atom, derived either from molecular oxygen or from peroxide, into a variety of organic substrates. Known as thiolate-ligated heme-proteins, these enzymes play critical roles in a number of important physiological processes, including the metabolism of pharmaceuticals, the transmission of signals between neurons, the control of blood pressure, and the immune system's response against tumor cells. These enzymes are unusual in that, although thiolate heme proteins generally would be expected to be less reactive than other heme proteins, these enzymes are both highly oxidizing and highly selective in their function. Green's research interest lies in understanding the role of the thiolate group in the reaction mechanism, using theoretical calculations and spectroscopy to study highly reactive intermediate compounds, which exist for a very short time during the reaction. "Knowledge gained from these investigations could be used to guide protein or catalyst design for industrial synthesis of organic chemicals," said Green. "If you could apply this chemistry directly to petroleum alkanes—the main components of crude oil—you could make a number of oxygen-containing compounds directly." Because the proteins are involved in the metabolism of many pharmaceuticals, better understanding of their chemistry also may aid the design of targeted drugs. A second area of research in the Green group involves selenium-containing proteins. Over 30 such proteins have been identified, many of these only in the last decade. The role of selenium in the reaction mechanisms is not well-understood. Green's investigations focus on how the local active site environment and the protein's substrate determine nature's choice of this element. Michael Green earned his doctoral and master’s degrees in chemistry at the University of Chicago in 1998 and 1994, respectively and bachelor’s degrees in chemistry and physics at Texas A&M University in 1992. Prior to joining the Penn State faculty in July 2002, he was a postdoctoral fellow at the California Institute of Technology from 1998 to 2002.
Peter Hudson studies disease dynamics—or how parasites and pathogens flow through animal populations, who infects whom, which individuals are important for disease transmission, and the consequences of infection. He studies infections of wild animals in detail so he can obtain an insight into how pathogens operate and why diseases emerge. His studies include not only the diseases that affect wildlife, but also the role of wildlife in transmitting diseases to other animals, including humans. “One of the consequences of the dramatic rise in HIV in sub-Saharan Africa has been an increase in secondary infections,” Hudson says. “Humans now are no longer simply recipients of disease, but also are reservoirs of infection that can bubble over into wildlife.” He is currently investigating groups of banded mongoose in Botswana that have become infected with human tuberculosis. He seeks to find the impact the disease has on the wildlife and if the wildlife can act as a long-term reservoir of this human pathogen. Hudson also is conducting a study with the Centro di Ecologia Alpina in northern Italy on Tick-Borne Encephalitis, a disease that causes significant mortality among children in Southern and Eastern Europe. The virus that causes this disease is carried by, but does not sicken, mice and deer. When ticks feed on mice, the mice transmit the virus from one tick to another. Part of the research challenge has been to identify both the conditions that lead to human infection and the importance of deer and mice in the multiplication of the infected ticks. Interestingly, more than 90 percent of the infections are caused by only 20 percent of the mice in the population. Hudson and his colleagues currently are researching data that indicate a correlation between virus transmission and old, territorial male mice. He also is looking at how this disease interacts with Lyme disease and whether the presence of one disease assists the other. He says, “Since arriving at Penn State we have initiated parallel studies to those in Italy, here in Pennsylvania. It is going to be interesting to see what we can learn from our Italian studies about the emerging disease problems in the United States.” Hudson comes from Scotland and was attracted to Penn State for the faculty's strengths in interdisciplinary research. “Penn State has so much to offer in terms of expertise and support,” he said. “The department is a truly wonderful place to work. I really was keen to come here and to work with the exciting group of young researchers who are investigating population dynamics.” Hudson serves as a committee member of the National Ecological Observatory Network (NEON) at the U. S. National Academy of Sciences and as a member of the tropical assessment committee of The Royal Society in England. In addition to many previous research fellowships, he is currently a visiting research professor at Imperial College in London, England; a visiting research professor at the University of Stirling in England; a visiting research professor at the University of Jyvaskyla in Finland; a visiting research professor at the Centro di Ecologia Alpina in Italy; and a research associate of the Consortium for Conservation Medicine in New York. Hudson earned his doctoral degree in the Department of Zoology at the University of Oxford in England in 1979 and his bachelor’s degree in zoology at the University of Leeds in England in 1974. Prior to joining Penn State in July 2002, he was at the University of Stirling in England, where he held a Personal Chair in Animal Ecology from 1998 to 2002 and was a reader in wildlife epidemiology from 1995 to 1998. From 1979 to 1995, Hudson worked intensively in the Highlands of Scotland, as a research fellow and then as manager of Upland Research with a research organization known as The Game Conservancy Trust, where he studied the ecology of diseases of the red grouse.
Kenneth Keiler uses biochemical and genetic approaches to understand the regulationof gene expression during bacterial development. "Bacteria are sometimes thought of as sacks of enzymes—simple organisms that do little more than grow and divide," said Keiler. "However, many bacteria can change their form or function in order to disperse themselves throughout the environment, to survive stressful environmental conditions, to provide specialized cells to aid the bacterial community, and to enter symbiotic or pathogenic relationships with other organisms." Bacterial cells alter the genes that they express in order to accomplish these morphological and functional changes. Keiler is interested in how cells control the activities of RNAs and proteins in order to differentiate. The primary model system in Keiler's lab is Caulobacter crescentus, an aquatic bacterium found in tap water. Each cell division in Caulobacter produces two distinct types of cells with different fates: one type with a stalk-like structure and another type that is able to swarm. The stalked cell immediately enters a round of cell division when it attaches to a substrate in the environment through its sticky stalk. The swarmer can colonize distant sites, but it cannot divide until it differentiates into a new stalked cell. In order for the bacterium to live these two different lifestyles, the genome of Caulobacter must encode all the necessary proteins for both a swarmer cell and a stalked cell, and the cell must be able to rapidly switch which set of genes is expressed. The focus of research in the Keiler lab is on how Caulobacter decides it is time to differentiate, and how it switches its gene-expression profile. Keiler earned a Ph.D. in biology at the Massachusetts Institute of Technology in 1995, and a master's degree in biology and a bachelor's degree in biology and chemistry at Stanford University in 1989. Prior to joining the Penn State faculty in the fall of 2002, Keiler was a Department of Energy Energy Biosciences Research Fellow at the Life Sciences Research Foundation of the Stanford University School of Medicine from1998 to 2002 and a Human Frontier Science Program Fellow at the Institut de Genetique et de Biologie Moleculaire et Cellulaire of the College de France from 1996 to 1997.
Emine Koc’s research interest is the structure and function of ribosomes in mammalian mitochondria. Mitochondria not only play a key role in cellular metabolism but also play a critical part in cell-death-signaling pathways and numerous disease states. Her research involves three distinct but complementary approaches to the investigation of mitochondrial translation machinery; in other words, the synthesis of mitochondrial proteins essential to respiration and synthesis of the molecule ATP. The first approach uses a combination of molecular biological and biochemical methods and proteomics techniques to investigate the similarity of function between mammalian mitochondrial ribosomes and prokaryotic ribosomes. “Mitochondrial ribosomes are so similar to those in bacteria that, in some cases, homologous factors can even be exchanged,” Koc said. “I am trying to make the connection between bacterial and mammalian mitochondrial translation systems. These studies will provide a better understanding of the mitochondrial translational machinery and may allow us to design specific drugs against bacterial infections and mitochondrial diseases.” Her second research focus is the role of mitochondrial ribosomes in apoptosis, or cell death. Two of the new classes of mitochondrial ribosomal proteins are proapoptotic proteins of unknown function, which might be major players in cellular-apoptotic-signaling pathways. She is interested in examining the possible interaction of mitochondrial ribosomes and/or mitochondrial ribosomal proteins with inner-membrane components in cell death. The final focus of Koc’s research is the role of mitochondrial ribosomes in disease. Tissues such as brain, muscle, and heart have high levels of mitochondria, which results in vulnerability of these tissues to mitochondrial dysfunction. Alterations in mitochondria are observed in more than one hundred different human diseases, including Alzheimer's and Parkinson's diseases, osteoarthritis, type-2 diabetes mellitus, and cancer. “There are ties between the expression of mitochondrial proteins and many disease states,” Koc said. “We will focus our studies on modifications and changes in expression of mitochondrial ribosomes in various disease states and cancer in order to develop biomarkers to define those ties.” Koc earned her doctoral degree in chemistry with a specialty in biochemistry and a minor in toxicology at New Mexico State University in 1997, after having earned her master’s degree in biochemistry in 1990 and her bachelor’s degree in biochemistry and chemistry in 1987 at Ege University in Turkey. Prior to joining the Penn State faculty in January 2003, she held a postdoctoral research position in the department of chemistry at the University of North Carolina from 1997 to 2002.
Si-Qiong June Liu studies fundamental properties of the nervous system, including the transmission of signals between synapses and the excitability of nerve membranes. In the central nervous system of mammals, glutamate released from one neuron triggers action in the next neuron by activating glutamate receptors. Repetitive activity of the neurons can produce lasting changes in the efficiency of synaptic transmission. “We are interested in learning how the synaptic transmission is moderated by neuron activity,” said Liu. “In the long term, this research may lead to understanding one of the mechanisms for learning and memory.” Liu’s research focuses on a recently discovered, unusual type of synaptic plasticity, in which neuron activity induces a very rapid change in the composition of glutamate receptors present at cell synapses in the cerebellum. The resulting change in the amplitude of the synaptic current, the calcium permeability, and its voltage dependence may play an important role in regulation of the cerebellar neural network. By characterizing the protein involved in synaptic plasticity, Liu will be able to determine the molecular mechanisms that increase and decrease neural activity. She uses slices of tissue from the cerebellum to model the networks because the cerebellum is composed of a well-defined neuronal network and the pathways of its various cell types have been thoroughly characterized. Key questions that Liu currently is investigating are the molecular mechanism underlying activity-dependent targeting of glutamate receptors, the signals that regulate the selective targeting of receptor subtypes within a single neuron, and whether neuron activity is responsible for the observed developmental changes in the expression of synaptic glutamate receptors. Liu earned a doctoral degree in biophysics at the University of Rochester in New York and a B. M. degree, which is equivalent to an M.D., at Beijing Medical University in China. Prior to joining the Penn State faculty in August 2002, she had postdoctoral fellowships at University College London in England and at Yale Medical School in Connecticut.
Kateryna Makova uses a combination of molecular and computational approaches to pursue her research interests, which include molecular evolution, population genetics, evolutionary genomics, bioinformatics, and human genetics. One of her current projects is the characterization of male-driven evolution, also known as male-mutation bias. Because a male's production of sperm cells is much greater than a female's production of egg cells, the number of cell divisions is higher in the male germ line than it is in the female germ line. Assuming that mutations are driven by the replication process, more mutations originate in sperm cells than in egg cells. Makova studies the mutations on the Y-chromosome, which is carried only by the male's sperm, and the X-chromosome, which is carried by both the sperm and the female's eggs, to calculate the male-to-female mutation-rate ratio for different types of mutations, including nucleotide substitutions, insertions and deletions, and others. In addition to shedding light on mutation mechanisms, this project is expected to answer questions about the importance of the age of a male at the time of reproduction and to provide other important information for use in genetic counseling. A second focus of Makova's research is the evolution of gene expression, which she analyzes by using microarray gene expression data along with published complete genome sequences. For example in one study that involves both the mouse and the human genome, Makova is analyzing the rate of divergence of gene expression between duplicate genes within a genome and also between the same genes in the two different genomes. "We want to determine whether the divergence in gene expression correlates with the protein-sequence divergence," she said. "In other words, are the evolution of the coding region and the evolution of mRNA expression coupled?" Makova's third area of interest is population genomics, which she studies in collaboration with Mark Shriver, assistant professor of anthropology, and his research group at Penn State. "With the completion of the Human Genome Project, it is possible to study human population genetics on a whole-genome scale—an approach that is more robust than earlier single-locus studies," she said. "Our specific interests include detecting positive selection and studying patterns of linkage disequilibrium." The results of this research are expected to provide direct information on the usefulness of particular human populations in disease-gene identification studies. Makova earned her doctoral degree in biology at Texas Tech University in 1999 and her master's degree in biochemistry and molecular biology at the Kiev State University in Ukraine in 1995. Prior to joining the Penn State faculty in July 2003, she had been a postdoctoral fellow in the Department of Ecology and Evolution at the University of Chicago since 1999.
Paula McSteen’s research focuses on signal transmission in specialized groups of cells, known as plant meristems—which develop into the plant's organs and support the growth of the plant throughout its lifetime. McSteen studies axillary meristems, which develop into branches and flowers and therefore play a fundamental role in plant architecture and reproduction. One goal of her research is to understand how cells perceive the hormonal signal that initiates the formation of an axillary meristem. She also is working to learn which genes and chemical signals cause the changes in gene expression, cell division, and expansion that are required for the formation of an axillary meristem. McSteen uses a genetic approach to the problem by screening for plants that develop defects during development of branches and flowers. By identifying the specific genes and signal pathways that are involved in the abnormal development, it is possible to learn their function in a normal plant. One of the mutants that is key to McSteen's research is the “barren inflorescence2” or “bif2” mutant in maize, which makes fewer branches and flowers due to defects in the initiation and growth of axillary meristems. McSteen has recently cloned the bif2 gene, has shown that it encodes a regulatory molecule that adds phosphates to other molecules, and has shown that the gene is expressed in meristem cells. McSteen plans to use a combination of genetic, genomic, molecular, biochemical, and physiological approaches to further characterize the role and function of the bif2 gene. “We have a number of questions to answer,” she says. “Which proteins does bif2 phosphorylate to regulate the development of axillary-meristems? What are the other components of the signal-transduction pathway? How do hormonal signals such as auxin and cytokinin regulate the pathway?” The model plants she uses to address these questions are maize and Arabidopsis, both of which have been well characterized by other researchers. The plants are representatives of two major classes of flowering plants: the monocotyledons, including maize, which have an embryo with only one seed leaf, and the dicotyledons, including Arabidopsis, which have an embryo with two seed leaves. The research will allow a comparison of the process of axillary-meristem formation and signal transduction in these two classes of plants. The ultimate goal is a broader understanding of plant development ranging from the whole plant to the cellular and molecular level. McSteen earned her doctoral degree in plant developmental genetics at the University of East Anglia in England in 1996 and her bachelor’s degree in natural sciences, specializing in genetics, at the University of Dublin in Ireland in 1991. Prior to joining the Penn State faculty in June 2003, she was a postdoctoral research fellow at the Plant Gene Expression Center in California from 1996 to 2003.
Anton Nekrutenko’s research blends bioinformatics—the study of the inherent structure of biological information and biological systems—with molecular evolution into the single field of evolutionary genomics. Evolutionary genomics, also known as comparative genomics, draws on genomic information from different species in order to find common functional elements such as genes. “Comparative genomics is an intuitive and simple way to increase the process of identifying specific protein-encoding segments of the DNA molecule,” said Nekrutenko. “The main problem with gene prediction is that genes occupy only a tiny proportion of our genome, like small islands in a sea of random—or not so random—noise.” Because there are many genetic similarities between species, the comparison of human-DNA sequences to those of other mammals increases precision in identifying these genetic islands. In addition to identifying the genes themselves, the technique is useful for identifying promoters, which are regions of the genome responsible for turning genes on and off. Identifying the structure and role of promoters is a key to understanding how organisms function. Because the number of genes does not reflect the complexity of an organism—that is, simple organisms can have almost as many genes as significantly more complex organisms—the more complex organisms must possess more sophisticated ways of regulating genes. Tracking similarities and differences in these promoters across species provides insight into the evolution of more complex organisms. "Isolating these control mechanisms provides answers to many fundamental evolutionary and genetic questions," Nekrutenko said. "Our approach to this problem is to identify the grouping of regions conserved among multiple species and to study their combinations. This approach allows us to focus on the common promoters." Nekrutenko earned his doctoral degree in biology at Texas Tech University in 1999 and his master's degree in biochemistry and molecular biology at Kiev State University in Ukraine in 1995. Prior to joining the Penn State faculty in April 2003, he was a postdoctoral research associate and instructor in the department of ecology and evolution at the University of Chicago from 1999 to 2003.
Benjamin Owen studies gravitational waves, the tiny sound-like vibrations in spacetime that carry information from violent events in the darkest parts of the universe. He also works on the astrophysics of neutron stars, the remains of massive stars that died in supernova explosions. His research interests include determining the properties of neutron stars theoretically and also looking for data, primarily through analysis of gravity waves, to test the theories. “Neutron stars are a lot like the Earth—solid crust, liquid mantle, waves, atmosphere—but matter in a neutron star is a hundred trillion times denser than rock, so nuclear reactions there play the role that chemical reactions play on Earth,” Owen said. “Neutron stars are a playground for ideas, and we can begin to test these ideas in new ways with observations from the new gravitational-wave detectors like the Laser Interferometer Gravitational-wave Observatory (LIGO) that now is being completed with National Science Foundation support.” Owen, who is interested in bridging the theoretical and the observational aspects of astrophysics, says his research includes both playing with ideas and experimenting with gravitational-wave observations. “In my theoretical work in gravity and astrophysics, I am trying to predict what the conditions are that can generate gravitational waves, what the signals should look like, and what the data can tell us about colliding stars, black holes, the guts of exploding stars, and other things you don't see with normal telescopes,” Owen said. “Another aspect of my research involves analyzing many terabytes of noisy data from incredibly precise experiments with gravitational-wave detectors to search for and interpret the tiny signals buried there.” He points out that the data analysts need the gravitational-wave theorists to tell them what the signals they seek will look like, while the theorists need the analyzed data to tell them what the universe looks like. “One of the great things about this field is that these two kinds of people actually talk to each other,” he said. “Penn State is great because it has people who do both things.” Prior to joining the Penn State faculty in August 2002, Owen was a postdoctoral researcher at the University of Wisconsin in Milwaukee from 2000 to 2002 and a research scholar at the Albert Einstein Institute in Potsdam, Germany from 1998 to 2000. Owen earned his doctoral degree in physics at the California Institute of Technology in 1998. He received his bachelor's degree from the department of physics and astronomy at Sonoma State University in 1993.
Donald Richards primarily researches multivariate statistics, the area of statistics concerned with data consisting of many sets of measurements taken from a number of individuals. His research interests emphasize the development of mathematical formulas that incorporate both multivariate statistics and mathematics—tools that are needed for the statistical analysis of data containing many variables. “I am working toward the day when we can solve every numerical problem in statistics exactly, without any need to resort to assumptions about sample sizes or to numerical approximations,” said Richards. “I spend a lot of time studying harmonic analysis, a subject with roots in physics. My research in mathematics is driven entirely by my goal to simplify statistical formulas.” In teaching, Richards combines insights from his research with his experience as a statistical consultant. He creates themes for classroom learning that can be shared by students from such disparate backgrounds as journalism, nursing, engineering, astronomy, and mathematics. “Statistical data are all around us, and students and their families are better off when they are able to think intelligently about these data,” he said. “Both teaching and research are important because the wisdom gained from research can be passed on rapidly to students and others in our society.” Richards has co-authored more than eighty papers, and has co-edited three books. He is currently an associate editor of the Annals of Statistics. He has served as a member and chair of the Committee on Fellows of the Institute of Mathematical Statistics, as a member of the National Research Council's Board on Mathematical Sciences and Committee on U.S. Mathematical Sciences Research Institutes, and as a member of the U.S. delegation to the 1994 General Assembly of the International Mathematical Union. Prior to joining the Penn State faculty in the fall of 2002, Richards was an associate professor and then professor of statistics at the University of Virginia from 1987 to 2002, where he chaired the Department of Statistics from 1994 to 2002. During the 2000-2001 academic year, he was a member in the School of Mathematics at the Institute for Advanced Study in New Jersey. He was an assistant and then associate professor at the University of North Carolina from 1981 to 1987, and an assistant professor of statistics at the University of the West Indies in Jamaica from 1979 to 1981. Richards was a visiting assistant professor at the University of Wyoming from 1983 to 1984. He received his doctoral degree in mathematical statistics at the University of the West Indies in 1978 and his bachelor's degree at the University of the West Indies in 1976.
Mercedes Richards studies binary stars, which are pairs of stars that were formed at the same time, like twins. Although these pairs have the same age, the stars mature at different rates. In close pairs, called interacting binaries, each star affects the evolution of its companion. Richards collects and analyzes observations of gas flows between stars in close binary systems. She also makes computer models and movies that show how these stars interact. Richards was the first astronomer to make clear images of the gravitational flow of gas between the stars in any interacting binary. Since these binaries are too distant to be resolved by the largest optical telescopes, Richards uses an indirect technique called tomography to develop images of the gas flow between the stars. “Tomography seems like magic,” said Richards. “You start out with shadows or projections, and use the shadows to infer the size and shape of the object that is producing the shadow.” In astronomy, the image is derived from numerous spectra, which show a pattern of Doppler shifts. These wavelength shifts are projections of the gas motions that can be used to make an image of the gas flows in the binary stars. While the technique has been used extensively in medicine, geophysics, and archeology, Richards was the first astronomer to apply tomography to the study of a group of binary stars in which the stream of gas flows directly from one star and hits the surface of the companion star. Richards was also the first astronomer to make theoretical hydrodynamic simulations of this special class of binaries. “It is like aiming a water hose at a curved wall and watching the water splash and continue moving away, except that the gas flows in binaries can have speeds of over a million miles per hour,” said Richards. Richards was chair of the Scientific Organizing Committee for a meeting on Astrotomography at the annual meeting of the International Astronomical Union in Sydney, Australia. She has participated in math and science enrichment programs for high-school students in Maryland, Michigan, New York, Vermont, Virginia, and Toronto. She was on the teaching faculty during a month-long international Vatican Observatory Summer School for graduate students in 1999. Prior to joining the Penn State faculty in fall 2002, Richards served
on the faculty of the University of
Virginia in Charlottesville. She was appointed as assistant professor
of astronomy there in 1987, promoted to associate professor in 1993, and
to professor of astronomy in 1999. In addition, she was a visiting scientist
during the
Erin Sheets’ research focuses on understanding fundamental chemical processes occurring on the cell surface that are critical for signal transduction and cellular function. Communication between cells and their surroundings is an essential part of processes as diverse as immune recognition, cell migration, and cell differentiation. Much of this communication occurs through cell-surface receptors and ligands that are bound to or released by neighboring cells. Sheets is particularly interested in two different, but related, biological research areas—the development of new tools for studying the dynamics of cellular signal transduction and the effort to understand the dynamics of certain biomembrane regions. “We are using nanotechnology and microtechnology to fabricate devices with well-defined architecture, both in space—by controlling size, pattern, and ligand density—and in time—by use of photoactivated ligands,” she said. “This approach allows us to probe the dynamics and distributions of molecules as they participate in cellular signaling.” Her research is expected to be broadly applicable to receptor-mediated signaling, allowing quantitative examination of critical molecular events in a variety of essential cellular functions. Certain lipid domains in biomembranes, enriched in cholesterol and saturated lipids, are increasingly recognized as active participants in cell signaling and membrane trafficking. Sheets studies the molecular dynamics of these complex biomembranes. She is developing methods to mimic them by patterning lipid bilayers or biomimetic membranes on substrates to investigate nucleation, stability, and lipid dynamics, as well as molecular coupling between the two leaflets that make up a lipid bilayer. These membrane studies will model how certain lipid regions facilitate signaling, with a goal of understanding how the biophysics of the membrane controls the biological function of living cells. “I joined the Department of Chemistry because I was excited by the collaborative environment that exists at Penn State, both within the department and throughout the University,” Sheets said. “Because our group works at the interface between the life sciences and the physical sciences, interdisciplinary programs such as the Huck Institute for the Life Sciences and the new Center for Nanoscale Science were particularly appealing to me, as was having the Penn State Nanofabrication Facility readily accessible.” Sheets earned her doctoral and master’s degrees in chemistry at the University of North Carolina in 1997 and 1994, respectively, and her bachelor’s degree in chemistry at Juniata College in Pennsylvania in 1991. Prior to joining the Penn State faculty in July 2002, she was a postdoctoral research associate in the Department of Chemistry and Chemical Biology at Cornell University in New York from 1997 to 2002.
Back to Science Journal Summer 2004 Index
|
|
|
Penn State Home Page | Eberly College of Science | Find a Person | Locate a Building | Search | Site Index Students
| Alumni
| Visitors
| Researchers
| Faculty and
Staff | Postdoctoral
Fellows | Corporate
Interests |
|
| This
page is maintained by Barbara K. Kennedy:
science@psu.edu, (814) 863-4682 and Kristen Devlin: krd111@psu.edu, (814) 863-8453 -- FAX (814) 863-2246 Eberly College of Science, Office of Public Information, 427 Thomas Building, University Park, PA 16802-2112 This page was last updated on 21June 2004 If you would like
to communicate with the keepers of the Eberly College of Science Web server,
send electronic mail to: science-web@thunder.science.psu.edu |
Sarah
Ades
David
Braun
Nathanial
Brown 
Bernd
Bruegmann
Doug
Cowen
Michael
Green
Peter
Hudson
Kenneth
Keiler
Emine
Koc
Si-Qiong
June Liu
Kateryna
Makova
Paula
McSteen
Anton
Nekrutenko
Benjamin
Owen
Donald
Richards
Mercedes
Richards
Erin
Sheets