New Faculty in the Eberly College of Science
Bryan Grenfell studies the dynamics of the spatial and temporal interaction of infectious diseases, particularly as related to the control of disease in human and animal populations. He combines the development of theory with pioneering analyses of empirical data sets from a range of systems to demonstrate how density-dependence and randomness, or disorder, interact to drive population dynamics in space and time. He is particularly interested in the population biology and control of foot-and-mouth disease and childhood infections such as measles. He also studies the evolutionary dynamics of pathogens such as influenza at different spatial scales.
In 2004 Grenfell was elected a Fellow of the British Royal Society. His research accomplishments have been recognized with the T.H. Huxley Medal from the Imperial College in the United Kingdom in 1991, the Scientific Medal of the Zoological Society of London in 1995, and an Order of the British Empire award in 2002. He also received a Professorial Fellow Award from the United Kingdom Biotechnology and Biological Sciences Research Council in 2003.
From 2001 to 2002 Grenfell was a member of the Chief Scientific Advisor’s Science Group on the control of the foot-and-mouth disease epidemic in the United Kingdom. He has served on United Kingdom Natural Environment Research Council (NERC) grant committees for Terrestrial Life Sciences from 1996 to 1999, and for Special Topics on Wildlife Diseases in 1991 and 1992. He served on the Infection and Immunity advisory panel from 1992 to 1995 and on the Biomathematics advisory panel from 1991 to 1996, both with the Wellcome Trust.
Grenfell has published 140 scientific papers about his research. Grenfell has been a member of the editorial advisory board for the Journal of Theoretical Biology from 2000 to 2003, and a member of the editorial board for the British Ecological Society Journal of Animal Ecology from 1993 to 2001. He was associate editor of American Naturalist from 1997 to 2000, was on the editorial council of the British Society for Parasitology from 1992 to 1994, and was the editor of a special issue of Parasitology on wildlife diseases in 1995.
He was co-organizer of a Royal Society discussion meeting on Chaos and Forecasting in 1994. In 1993 he was co-organizer of the Programme on Epidemic Models and organizer of a meeting on the Ecology of Infectious Diseases in Natural Populations, both at the Isaac Newton Institute for Mathematical Sciences in Cambridge, United Kingdom.
Prior to joining Penn State in September 2004, Grenfell was at the University of Cambridge, United Kingdom, as professor of population biology from 2002 to 2004 and as a member of the faculty of the Department of Zoology from 1990 to 2002. He was a lecturer in the Department of Animal and Plant Sciences at the University of Sheffield, United Kingdom, from 1986 to 1990. He also was a research fellow in pure and applied biology at the Imperial College in London from 1981 to 1986, and was a research assistant in biology at the University of York, United Kingdom, from 1977 to 1981.
Grenfell received his bachelor’s degree with honors in zoology from the Imperial College of London, United Kingdom, in 1976. He received both his master’s degree in biological computation and his doctoral degree in biology from the University of York, United Kingdom, in 1977 and 1980, respectively.
Murali Haran, assistant professor of statistics
Murali Haran investigates models used to make inferences about location-based data. One problem to which he applies such methods is the study of the geographical distribution of diseases. Sophisticated models for estimating the actual prevalence of disease in a particular region use information both from within that region and from neighboring regions, because adjacent regions are assumed to share some common characteristics. In addition to understanding the properties of such models and finding appropriate models for a given problem, Haran works on developing the finely tuned computational algorithms necessary to obtain estimates of disease prevalence, and other important information, based on the model and data. Existing computational algorithms for these complex models are often unreliable and take too long. Haran works on algorithms that are more efficient and accurate.
Haran also has been involved in collaborative efforts with public-health researchers seeking to develop models for data from studies of air quality, examining discrepancies between an individual’s actual exposure to particles in the air and exposure measurements taken by air-pollution monitors.
Haran is a member of the American Statistical Association and the Institute of Mathematical Statistics. His research accomplishments have been recognized with a student-travel award to attend the Joint Meetings on Bayesian Statistical Sciences in 2001 and a travel award to attend the Seventh International Meeting on Bayesian Statistics of the International Society for Bayesian Analysis in 2002. In 2004, he received a Young Investigator Award from the Institute of Mathematical Statistics that enabled him to give a presentation at the Conference on Markov Chain Monte Carlo Methods at Bormio, Italy.
Prior to joining Penn State during the fall semester of 2004, Haran was a research assistant at the University of Minnesota from 1999 to 2003 and was an intern with Medtronic Corporation during 1998. At Carnegie Mellon University, he was a research assistant in the Robotics Institute from 1996 to 1997 and a programmer in the Department of Statistics in 1995. He received his master’s and doctoral degrees in statistics from the University of Minnesota in 2001 and 2003, respectively, and received his bachelor’s degree in computer science at Carnegie Mellon University in 1997.
Dezhe Jin, assistant professor of physics
Dezhe Jin focuses on theoretical analysis of the biophysical properties of neural networks and their applications to neurobiological functions. Theoretical neurobiology is an emerging frontier that involves the expansion of physics into biology. The goal of this research is to construct biologically detailed computational models of neurobiological functions guided by the theoretical studies of neural networks. Jin’s research currently includes computational models of neurobiological functions, such as song generation and recognition in songbirds, as important animal models for studying speech generation and recognition; motor control in basal ganglia; the complex-pattern-recognition problem of olfaction as observed in insects and mammals; and processing of visual information, including the formation of feature maps in the visual cortex.
Jin explains, “Much of the previous work on neural networks was focused on rate encoding. These models ignore how neurons interact with individual spikes, or pulses of neuronal membrane potential—the difference between the electrical potentials inside and outside of the cell—that transmit signals between neurons. Instead, they approximate neuronal interactions only as a function of the average spiking rate of neurons.” He continues, “Our research is focused on more biologically realistic spiking models that preserve the pulse-coupled nature of neural interactions. When compared to rate models, these spiking models have richer and faster dynamics that can be exploited for information processing in the brain.”
The brain, which has large numbers of interacting neurons, is one of the most complex and fascinating dynamical systems in nature. “Neurobiology is a rapidly growing field with continuing innovations in experimental techniques,” says Jin. “Our theoretical modeling is guided by theoretical studies of neural networks and is shaped by experimental data. We work closely with experimental groups across the country, employing tools drawn from nonlinear dynamics, statistical mechanics, and computational physics. The future demand for modeling work will increase, and a theoretical-neurobiology program will position tomorrow’s physics students to meet the demand.”
Jin is a member of the American Physical Society, the Society for Neuroscience, and the scientific-research society Sigma-Xi. He is a referee for Physical Review Letters, Physical Review E, Physics of Plasmas, Physics of Fluids, and the Institute of Electrical and Electronics Engineers (IEEE) journal Transactions on Neural Networks.
Jin has presented invited talks and presentations at universities and institutions across the United States, including an invited talk at the 41st Annual Meeting of the American Physical Society’s Division of Plasma Physics in 1999.
Prior to joining Penn State during the fall semester of 2004, Jin was a research associate at the Howard Hughes Medical Institute from 2001 to 2004 and was a postdoctoral fellow at the Massachusetts Institute of Technology from 2000 to 2004. He was a postdoctoral researcher at the University of California in San Diego in 1999 and 2000, and was an assistant lecturer at Tsinghua University in Beijing, China, from 1990 to 1992.
Jin received his bachelor’s and master’s degrees in physics from Tsinghua University in Beijing, China, in 1990 and 1994, respectively, and received his doctoral degree in physics from the University of California in San Diego in 1999.
Kouacou Konan, assistant professor of biochemistry and molecular biology
Kouacou Konan conducts research on the Hepatitis-C virus (HCV) and related viruses. HCV is one of the leading causes of liver cancer worldwide, but currently there is no effective therapy for HCV patients. The long-term goal of Konan’s research is to understanding how HCV and related viruses exploit the function and ultrastructure of the host’s secretory apparatus to support their own replication.
Viral proteins that affect the movement of the host’s proteins or membranes can be targets for antiviral drug design. Like most positive-stranded RNA viruses, HCV replicates in the cytoplasm of infected cells, resulting in the inhibition of protein traffic in the host’s cells and the production of rearranged membranes called membranous webs. These membranes are proposed to be the site of viral-RNA replication. Konan’s goal is to determine the intracellular origin of these membranes, as well as how the viral proteins are recruited to these membranes.
HCV is a member of a family of viruses that includes Dengue virus, West Nile virus, and Bovine-Viral-Diarrhea virus (BVDV). BVDV and Dengue virus cause serious diseases that are often fatal in cattle and humans, respectively. Unlike HCV, these viruses can be propagated in tissue-culture cells and therefore provide useful models for understanding HCV replication in vitro. Konan is interested in understanding how BVDV or Dengue-virus replication affects protein transport and which viral proteins are involved in the process. He would like to generate mutant strains of the viruses in order to examine their physical and biochemical characteristics in both cell cultures and transgenic-mouse models.
Konan also is interested in the possibility that HCV can induce membranous-web formation in yeast. Because strains of yeast can be easily mutated to produce specific features, yeast is an attractive model organism for determining what cellular factors are required for the formation of novel intracellular membranes.
Konan’s research accomplishments have been recognized with a Summer Floyd Fellowship from Indiana University in 1989, an Institutional National Institutes of Health Research Service Award in 2000, and a National Institutes of Health Mentored Research Scientist Development (K01) award in 2002. He received travel awards to attend the Ninth International Meeting on Hepatitis-C Virus and Related Viruses in 2002 in San Diego, California, as well as the 1994 Annual Conference of the International Society of Interferon and Cytokine Research in Budapest, Hungary.
Prior to joining Penn State in the fall semester of 2004, Konan was a research associate at Stanford University from 2002 to 2004. He was a postdoctoral fellow at Stanford University from 1995 to 2002, and was a research assistant at Indiana University from 1992 to 1995. He received his bachelor’s degree in
genetics from the University of Abidjan, Ivory Coast, in 1986. He received his master’s and doctoral degrees in microbiology and molecular biology from Indiana University in 1990 and 1995, respectively.
Christian Malone, assistant professor of biochemistry and
Christian Malone uses genomic, cell-biological, and traditional-genetic techniques to study the mechanism by which the nucleus of a cell interacts structurally with other cellular components, primarily in the model organism C. elegans, during centrosomal attachment, nuclear positioning, and nuclear migration.
Mispositioned nuclei in muscle cells have been implicated in muscular dystrophy. Nuclear migration is essential for fertilization and for the differentiation and growth of epithelial cells, the membranous tissue forming the covering of most internal and external surfaces of the body and its organs. Malone’s work has demonstrated that nuclei and centrosomes—an area in the cell where microtubules are produced—must be attached at the time the nuclear envelope breaks down to form a functional mitotic spindle. The two centrosomes move to opposite ends of the nucleus, where microtubules grow from each centrosome into a “spindle,” which is responsible for separating replicated chromosomes into the two daughter cells. Malone also studies how the proteins necessary for interaction are positioned on the outer membrane of the nuclear envelope.
An example of the type of interaction he studies is the association
between the centrosome and the nucleus. These organelles are
tightly attached during interphase—the stage between
successive cell divisions—in a variety of organisms and
cell types, yet the significance and mechanism of this attachment
have been poorly understood. To characterize the mechanism
of centrosomal attachment, Malone identified and cloned the
attachment-gene zyg-12, which encodes multiple forms of Hook-like
proteins. In humans, members of the Hook family of proteins
mediate the interaction of membrane-bound organelles, such
as the Golgi—a type of nerve cell—with the internal
framework of the cell known as the microtubule cytoskeleton.
Malone’s research accomplishments have been recognized with an American Cancer Society fellowship in 2002 and a National Defense Science and Engineering fellowship in 1994. In 2004 he received a travel award to attend the Novartis Symposium on Nuclear Organization in Development and Disease.
Malone is a member of the American Society for Cell Biology. He is a peer reviewer for the journal Nature, Molecular Biology of the Cell, BioEssays, and the Journal of Cell Science. In 2003, he made presentations at the 43rd Annual Meeting of the American Society for Cell Biology in San Francisco, California, and at the 14th International C. elegans Meeting in Los Angeles, California. In 2002 he made presentations at the 42nd Annual Meeting of the American Society for Cell Biology in San Francisco, California, and at the European Molecular Biology Organization and European Molecular Biology Laboratory (EMBO/EMBL) Conference on Centrosomes and Spindle Pole Bodies in Heidelberg, Germany.
Prior to joining Penn State in the fall semester of 2004, Malone was a postdoctoral fellow at the University of Wisconsin from 1999 to 2004 and conducted graduate research at the University of Colorado from 1994 to 1999.
Malone received his bachelor’s degree in biology from the Albertson College of Idaho in 1993. He received his doctoral degree in molecular, cellular, and developmental biology from the University of Colorado in 1999.
Ken O’Hara, assistant professor of physics
Ken O’Hara investigates ultra-cold atoms confined in a “periodic-lattice potential” formed from laser beams. The modulated light intensity produced by several interfering laser beams provides a periodic-lattice potential in which the atoms move. This “optical lattice” mimics the potential that electrons experience when they move around a crystalline lattice in solid-state matter.
Atoms in an optical lattice should exhibit many of the same extraordinary phenomena observed in solid-state systems such as magnetic ordering, high-temperature superconductivity, and the quantum Hall effect. Optical lattices also can be used to study the behavior of atoms confined in nanotubes formed from light. “What makes studying these phenomena in an atomic system so exciting is that many experimental parameters in the system can be precisely controlled,” O’Hara explains. “For example, we can modify the density of the atoms, the geometry of the lattice, the degree of disorder in the lattice, and even the interaction strength between the atoms. These modifications allow us to engineer idealized model systems in which to study quantum many-body phenomena such as magnetism, superfluidity, and quantum phase transitions.” He adds, “We also expect to have the ability to engineer systems that have no analog in solid-state physics, which could lead to the discovery of entirely new states of matter.”
O’Hara is a member of the American Physical Society and the Optical Society of America and of the Phi Beta Kappa honor society. His research accomplishments were recognized with a postdoctoral fellowship from the National Research Council to conduct research at the National Institutes of Standards and Technology (NIST) in 2002.
O’Hara is a referee for Physical Review Letters, Physical Review A, and Optics Communications. He was a keynote speaker at the Workshop on Bose-Einstein Condensation and Quantum Information in Queensland, Australia, in 2003 and participated in the National Institute of Standards and Technology Quantum Information and Bose-Einstein Condensation Seminar Series in 2002. In 2001, he gave presentations at the 17th Interdisciplinary Laser Science Conference in California and the 8th Rochester Conference on Coherence and Quantum Optics in New York.
Prior to joining Penn State in the fall semester of 2004, O’Hara was a postdoctoral research associate at the National Institute of Standards and Technology from 2002 to 2004. At Duke University, he was a research associate from 2000 to 2002, a physics instructor in 2001, and a research and teaching assistant from 1994 to 2000. He also was a research assistant at the University of Notre Dame from 1993 to 1994. As a research assistant at Ohio State University, he participated in the U.S. Geological Survey Antarctica Project during the summers of 1990 and 1991, and worked in the Supercomputer Center from 1989 to 1990.
O’Hara received his bachelor’s degree in physics, magna cum laude, from the University of Notre Dame in 1994. He received his master’s degree and doctoral degree in physics from Duke University in 1997 and 2000, respectively.
Damla Sentürk, assistant professor of statistics
Damla Sentürk is developing a “covariate-adjusted regression model,” which provides a description of the relationships between random variables after adjusting for a confounding covariate. Her special interest in these models stems from their applications to problems in the life sciences, such as the analysis of the regression of the concentrations of plasma- fibrinogen, a major plasma-protein coagulation factor, on serum levels of the iron-binding glycoprotein transferrin, useful for hemodialysis patients.
Covariate-adjusted regression and correlation analysis is motivated mainly by regression problems in the life sciences, where adjustments to different confounders, like body mass index, is common.
Sentürk is a member of the American Statistical Association and the Institute of Mathematical Statistics. Her research accomplishments have been recognized with a summer research fellowship in 2003, a graduate fellowship for engineering or computer-related applications and methods in 2002, and a Sacramento Statistical Association Student Fellowship Award in 2001. She has served as a reviewer for Statistica Sinica, the Journal of Nonparametric Statistics, the Journal of Statistical Planning and Inference, and the Journal of the Royal Statistical Society in the United Kingdom.
Sentürk gave an invited presentation at the 2002 Annual Meeting of the Sacramento Statistical Association. Also in 2002, she gave presentations at the International Conference on Current Advances and Trends in Nonparametric Statistics in Greece, at the Western North American Regional Meeting of the International Biometrics Society, and at the 40th Anniversary Conference of the Texas A&M University Department of Statistics.
Prior to joining Penn State in the fall semester of 2004, Sentürk was a graduate research assistant and graduate teaching assistant at the University of California at Davis from 1999 to 2004, where she also was an associate instructor during the summers of 2001 and 2003. She received her bachelor’s degree in mathematics from the Bogaziçi University in Turkey in 1999. She received her master’s and doctoral degrees in statistics from the University of California at Davis in 2001 and 2004, respectively.
Deirdre Shoemaker, assistant professor of physics
Deirdre M. Shoemaker studies gravitational waves—ripples in the fabric of the universe that scientists call “spacetime.” Although they never have been detected directly, gravitational waves are predicted by Einstein’s theory of General Relativity. These waves have a very long reach in both space and time because they have a very weak interaction with matter, which also makes them extremely difficult to detect. Now, however, there are observatories, such as the Laser Interferometer Gravitational Wave Observatory (LIGO) in the United States, and others around the world, that are beginning to search the universe for gravitational waves. These observatories collect massive amounts of data that scientists are examining for signs of large gravitational waves such as those thought to be produced by the collision and merger of two black holes. Black-hole collisions are predicted to occur throughout our universe.
Shoemaker’s primary area of research is the study of theoretical models of gravitational wave sources, especially those involving black holes, that are done by computational gravitational physics—often called numerical relativity—to mine sources of gravitational waves for observable clues that could reveal the physics of their generating sources. She focuses on solving Einstein’s equations that describe black-hole solutions. Such solutions require the use of cutting-edge computational techniques, astrophysics, and General Relativity. The goal of this work is to understand the non-linear regime of gravity and its effect on the environment around black holes, particularly the black-hole engines that produce gravitational waves.
“A black hole’s environment is very interesting,” says Shoemaker. “Smaller-scale collisions involve black holes just slightly larger than our sun. When two black holes draw near enough to each other to form a binary pair where their gravitational environments affect each other, it might be possible for us to detect their collision via ground-based gravitational-wave detectors, depending on their distance from us.” She continues,
“Astronomers are gathering evidence that indicates that most galaxies have a central black hole, often millions or billions of times larger than our Sun. When these galaxies crash into each other, so do their central black holes. The gravitational waves produced in these collisions will be detectable by the space-based detector, LISA.” The Laser Interferometer Space Antenna is a joint mission between the European Space Agency and NASA ’s Office of Space Science.
Shoemaker is a member of the American Physical Society, and of the Phi Beta Kappa, Sigma Pi Sigma, and Golden Key National Honor Societies. Her research accomplishments have been recognized with a Distinguished Dissertation Award and a Professional Development Award from the University of Texas in 1999, and a Sigma Pi Sigma Undergraduate Research Award in 1994.
She has presented invited talks in the United States and Mexico and has contributed talks at conferences in Canada, Italy, and Germany.
Prior to joining Penn State in the fall semester of 2004, Shoemaker was a research associate in the Center for Radiophysics and Space Research at Cornell University from 2002 to 2004. She was a postdoctoral fellow in the Penn State Center for Gravitational Physics and Geometry and in the Center for Gravitational Wave Physics from 1999 to 2002. She was at the University of Texas as a graduate research assistant in the Center for Relativity in 1997 and 1998, and as a teaching assistant from 1995 to 1997. She also had been a teaching assistant at Penn State in 1995.
Shoemaker received her bachelor’s degree with honors in physics and in astronomy and astrophysics from Penn State in 1994. She received her doctoral degree in physics from the University of Texas at Austin in 1999.
Aleksandra B. Slavkovic, assistant professor of statistics
Aleksandra B. Slavkovic conducts research focusing on developing and applying statistical methods for issues of data privacy and data confidentiality. One goal of her research is to limit the release of sensitive information about individuals and groups that are part of statistical databases, while allowing for accurate statistical analysis of the data. Slavkovic’s past and current work is a unique integration of diverse results and presents new theoretical links between disclosure limitation, graphical models, statistical theory, and computational algebraic geometry.
Beyond statistical approaches to confidentiality and data disclosure, Slavkovic is interested in statistical data mining, application of statistical methods to social sciences and human-computer interaction, algebraic statistics, causal inference, and the characterization and compatibility of probability distributions for contingency tables.
Slavkovic previously served as a consultant for the National Academy of Sciences and National Research Council Committee to Review the Scientific Evidence of Polygraph. This work involved close interaction with psychologists, physiologists, polygraphers, and statisticians; and spanned some of the principal areas of statistical applications such as biological science, information technology, psychology, social science, and policy. She actively participated in the committee’s working sessions and in the preparation of the final report. She also carried out a separate research project evaluating polygraph data.
Slavkovic’s research accomplishments were recognized by the American Statistical Association with an Honorable Mention Prize for the Best Student Paper from the Committee on Statisticians in Defense and National Security in 2003. She also received an Honorable Mention for the Best Contributed Poster from the Fifth International conference on Forensic Statistics in 2002. Slavkovic has presented invited talks at conferences and workshops across the United States and internationally.
Slavkovic is a member of the Phi Kappa Phi National Honor Society, the Institute of Mathematical Sciences, and the American Statistical Association. Prior to joining Penn State in the fall semester of 2004, Slavkovic was an instructor and teaching assistant in the Department of Statistics at Carnegie Mellon University from 2000 to 2004. She was a research assistant in the School of Computer Science at Carnegie Mellon University from 1997 to 1999.
Slavkovic received her bachelor’s degree, magna cum laude, in psychology from Duquesne University in 1996. She received a master’s degree in human-computer interaction in 1999, and master’s and doctoral degrees in statistics, in 2001 and 2004 respectively, from Carnegie Mellon University.