All Seminars
| Title: Higher-dimensional Tate-Shafarevich groups |
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| Seminar: Algebra and number theory |
| Speaker: Daniel Krashen of University of Georgia |
| Contact: Skip Garibaldi, skip@mathcs.emory.edu |
| Date: 2010-10-19 at 3:00PM |
| Venue: MSC E408 |
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| Abstract: his talk will examine local-global principles for objects defined over fields of the form $K(X)$ where $K$ is a complete discretely valued field and $X/K$ is a curve. In particular, we will examine torsors for linear algebraic groups and the measure the failure/success of local-global principles defined with respect to a variety of different types of ``local versions" of our fields. This is joint work with David Harbater and Julia Hartmann. |
| Title: Sum rules for eigenvalues of differential equations on surfaces and graphs |
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| Seminar: Analysis and Differential Geometry |
| Speaker: Professor Evans Harrell of Georgia Institute of Technology |
| Contact: Vladimir Oliker, oliker@mathcs.emory.edu |
| Date: 2010-10-19 at 4:00PM |
| Venue: MSC W301 |
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| Abstract: I will discuss ``sum rule'' identities that can be derived at the level of operator algebra, and their uses to prove sharp inequalities for eigenvalues of elliptic differential operators on manifolds and on metric graphs. Three uses of the sum rules are to find connections between Laplace spectra and curvature on "quantum waveguides," to find connections between Schr\"odinger spectra and topology on "quantum graphs," and to yield short, efficient derivation of sharp semiclassical estimates of Lieb-Thirring type in the same situations. Parts of this work are joint with Demirel, Hermi, and Stubbe. |
| Title: Breaking the O($n^2$) bit barrier: Scalable Byzantine Agreement with an Adaptive adversary |
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| Seminar: Computer Science |
| Speaker: Jared Saia of University of New Mexico |
| Contact: Michelangelo Grigni, mic@mathcs.emory.edu |
| Date: 2010-10-19 at 4:00PM |
| Venue: MSC W201 |
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| Abstract: We present an algorithm for Byzantine agreement that is scalable in the sense that each processor sends only soft-O($sqrt(n)$) bits, where n is the total number of processors. Our algorithm succeeds with high probability against an adaptive adversary, which can take over processors at any time during the protocol, up to the point of taking over arbitrarily close to a 1/3 fraction. Moreover, our algorithm works in the presence of flooding: processors controlled by the adversary can send out any number of messages. We assume the existence of private channels between all pairs of processors but make no other cryptographic assumptions. Finally, our algorithm has latency that is polylogarithmic in n. To the best of our knowledge, ours is the first algorithm to solve Byzantine agreement against an adaptive adversary, while requiring o($n^2$) total bits of communication.\\ \\ Jared Saia obtained his PhD from the University of Washington and is now an Associate Professor at the University of New Mexico. His broad research interests are in theory and algorithms with strong interests in distributed algorithms, game theory, security, and spectral methods. A current interest is determining how large groups can function effectively when there is no leader. He is the recipient of several awards including the NSF CAREER Award, the UNM Junior Faculty Research Excellence Award, and several best paper awards. |
| Title: Sesquilinear forms |
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| Seminar: Algebra and number theory |
| Speaker: Eva Bayer-Fluckiger of Swiss Federal Institute of Technology, Lausanne (EPFL) |
| Contact: R. Parimala, parimala@mathcs.emory.edu |
| Date: 2010-10-15 at 3:00PM |
| Venue: MSC E408 |
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| Abstract: The aim of this talk is to show how classification questions concerning sesquilinear forms (without symmetry) over rings with involution can be reduced to questions on hermitian forms in certain hermitian categories. Using the theory of Quebbemann, Scharlau and Schulte, one can then obtain results such as Witt cancellation as well as some base change properties in the case where the ring is a finite dimensional algebra over a field of characteristic not 2. |
| Title: Degree Ramsey Numbers of Graphs |
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| Seminar: Combinatorics |
| Speaker: Kevin Milans of The University of South Carolina |
| Contact: Dwight Duffus, dwight@mathcs.emory.edu |
| Date: 2010-10-15 at 4:00PM |
| Venue: W306 |
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| Abstract: A graph H arrows a graph G if every 2-edge-coloring of H contains a monochromatic copy of G. The degree Ramsey number of G is the minimum k such that some graph with maximum degree k arrows G. Burr, Erdos, and Lovasz found the degree Ramsey number of stars and complete graphs. We establish the degree Ramsey number exactly for double stars and for the cycle on four vertices. We prove that the degree Ramsey number of the n-cycle is at most 96 when n is even and at most 3458 in general. Consequently, there are very sparse graphs that arrow large cycles. We present a family of graphs in which the degree Ramsey number of G is bounded by a function of the maximum degree of G and ask which graph families have this property. This is joint work with Tao Jiang, Bill Kinnersley, and Douglas B. West. |
| Title: Mining Medical Data To Improve Disease Diagnosis and Treatment |
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| Seminar: Computer Science |
| Speaker: Carlos Ordonez of University of Houston |
| Contact: Li Xiong, lxiong@mathcs.emory.edu |
| Date: 2010-10-14 at 4:00PM |
| Venue: MSC W301 |
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| Abstract: Abstract: Medical data sets have been generally analyzed with statistical techniques like regression, time series and statistical tests, among others. In this talk we will motivate how data mining techniques, traditionally used on large databases, can improve medical data analysis, where data sets are generally much smaller and attributes exhibit high variability. We will emphasize the importance of association rules and OLAP cubes. From a medical standpoint, we will summarize how our research helps heart disease and cancer diagnosis and treatment.\\ \\ Bio: Carlos Ordonez received a degree in applied mathematics and an M.S. degree in computer science, from UNAM University, Mexico, in 1992 and 1996, respectively. He got a Ph.D. degree in Computer Science from the Georgia Institute of Technology, in 2000. Dr Ordonez worked six years extending the Teradata DBMS with data mining algorithms. He is currently an Assistant Professor at the University of Houston. His research is centered on the integration of statistical and data mining techniques into database systems and their application to scientific problems. |
| Title: E8's publicity photo and a cobalt niobate magnet |
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| Seminar: Algebra and number theory |
| Speaker: Skip Garibaldi of Emory University |
| Contact: Skip Garibaldi, skip@mathcs.emory.edu |
| Date: 2010-10-07 at 4:00PM |
| Venue: MSC W301 |
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| Abstract: The first goal of this talk is to answer the question: "What is E8?" The second goal is to explain the relationship between 'the' Lie group E8, its publicity photo, and a recent experiment involving a cobalt niobate magnet reported in Science. |
| Title: Galois theory of iterated endomorphisms |
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| Seminar: Algebra and Number Theory |
| Speaker: Jeremy Rouse of Wake Forest |
| Contact: Ken Ono, ono@mathcs.emory.edu |
| Date: 2010-10-05 at 3:00PM |
| Venue: MSC E408 |
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| Abstract: The basic question we study is the following. Given an abelian algebraic group $A$ defined over $\mathbf{Q}$, a point $\alpha$ in $A(\mathbf{Q})$, and a prime $\ell$, what fraction of primes $p$ have the property that the reduced point $\alpha$ in $A(\mathbf{F}_p)$ has order coprime to $\ell$? Associated with the choice $\alpha$ and $\ell$ is an arboreal Galois representation. We give surjectivity criteria for this representation and use these to answer the question above in many examples where $A$ is an algebraic torus or an elliptic curve. |
| Title: Quermassintegrals inequalities and curvature measure problem |
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| Seminar: Analysis and Differential Geometry |
| Speaker: Professor Junfang Li of University of Alabama at Birmingham |
| Contact: Vladimir Oliker, oliker@mathcs.emory.edu |
| Date: 2010-10-05 at 4:00PM |
| Venue: MSC W301 |
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| Abstract: We will present some recent joint work on two different but related problems : quermassintegral inequalities and prescribing curvature measure problem. We use a parabolic fully nonlinear partial differential equation to prove isoperimetric inequalities for quermassintegrals on a starshaped bounded domain. On the other hand, curvature measure can be viewed as a local version of the quermassintegrals. The general k-th prescribing curvature measure problem is equivalent to a second order fully nonlinear elliptic partial differential equation defined on a unit sphere. It has been an open problem for the existence of an admissible solution of this equation. The major new contribution of our recent work is the a priori $C2$ estimates for admissible solutions which leads to the existence theorems. |
| Title: Healthcare Information Technology: Opportunities for Computer Scientists to Make a Real Difference |
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| Colloquium: Computer Science |
| Speaker: Lucila Ohno-Machado of University of California, San Diego |
| Contact: Li Xiong, lxiong@mathcs.emory.edu |
| Date: 2010-10-01 at 1:00PM |
| Venue: W306 |
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| Abstract: Healthcare has lagged behind other industries in the utilization of information technology. Some reasons for this gap are related to the complex nature of physician-patient interactions, lack of systems that can seamlessly be embedded in clinical workflows, and limited collaboration and communication that cross the boundaries between medicine, computer science, and engineering. Changes in the healthcare landscape in the U.S. provide a unique opportunity to develop new ideas for integrating information technology into healthcare. Reducing costs and providing healthcare for all requires the development of more efficient systems of care, in which not only public health indicators and institutional expenditures are monitored, but also objective quality of care measures and individual patient outcomes. High resolution monitoring cannot be achieved without computer-based systems that are able to integrate data from clinical encounters, billing systems, and research studies for meaningful data analysis, pattern recognition, and high fidelity simulations. There are a variety of areas in which computer scientists can partner with clinicians and other decision makers, but the development of such partnerships requires a systematic approach. In biomedical informatics training programs, the goal is to provide training in a complementary area for individuals with computer science or health sciences backgrounds, and to train the next generation of researchers. While this covers important ground, more needs to be done. There is currently limited work in the area of training the existing generation of computer scientists and clinician leaders on how to work together to approach current healthcare challenges in a novel way. I will present a model for crossing disciplinary and geographical barriers in order to promote health and alleviate the burden of disease, and present several examples in which this could be done today. Biography: Lucila Ohno-Machado, MD, PhD, is Professor of Medicine and founding chief of the Division of Biomedical Informatics at the University of California San Diego. She received her medical degree from the University of Sao Paulo and her doctoral degree in Medical Information Sciences and Computer Science from Stanford University. Prior to her current role, she was director of the training program for the Harvard-MIT-Tufts-Boston University consortium in Boston, and director of the Decision Systems Group at Brigham and Women’s Hospital, Harvard Medical School. Her research focuses on the development of new evaluation methods for predictive models of disease, with special emphasis on the analysis of model calibration and implications in healthcare. She is an elected member of the American College of Medical Informatics and the American Institute for Medical and Biological Engineering, and associate editor for the Journal of the American Medical Informatics Association and the Journal for Biomedical Informatics. She has lectured in Asia, Europe, Africa, and South America and is currently director of the Biomedical Research Informatics Global Health program funded by the NIH. At UCSD, she leads a multidisciplinary group of faculty, trainees, and staff whose research ranges from foundations of biomedical informatics to applications in healthcare. The former includes the development of new algorithms to analyze genomic and clinical data and to prevent disclosures that can compromise patient privacy, and the latter includes applications of pattern recognition algorithms to prognosticate disease using large repositories of data. |