All Seminars
| Title: Cryptanalysis of small-valued secret exponents in RSA cryptosystems |
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| Undergraduate Honors Thesis Defense: N/A |
| Speaker: Richard Oh of Emory University |
| Contact: Skip Garibaldi, skip@mathcs.emory.edu |
| Date: 2010-04-07 at 9:35AM |
| Venue: W306 |
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| Abstract: |
| Title: Learning via Mobile Platforms: The Possibilities and Pitfalls |
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| Colloquium: Computer Science |
| Speaker: Valerie Summet of Georgia Institute of Technology |
| Contact: Susan Guppy, sguppy@emory.edu |
| Date: 2010-04-02 at 3:00PM |
| Venue: MSC W301 |
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| Abstract: Advancing personalized learning has been named as one of the twenty grand challenges for the 21st century by the National Academy of Engineering. One method of personalizing the learning environment is to allow people to learn anytime, anywhere by using their mobile phone as a learning platform. But is learning in a distracted environment via mobile phones effective? In this talk, I present a study designed to evaluate this question. Using a customized web-application, I evaluated 40 participants’ ability to learn American Sign Language vocabulary words via mobile platforms and conventional computing platforms. Over the course of two weeks, participants learned 80 distinct vocabulary words and were evaluated on both receptive and generative language skills. The results of this study show that mobile platforms can support learning and suggest that further personalization is needed to help maximize its impact. In light of these results, this talk concludes with a discussion of future applications aimed at supporting personalized learning in different domains. |
| Title: Polynomials non-negative on non-compact subsets of the plane |
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| Type: Dissertation Defense |
| Speaker: Ha Nguyen of Emory University |
| Contact: Ha Nguyen, hnnguye@emory.edu |
| Date: 2010-04-02 at 4:00PM |
| Venue: MSC W201 |
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| Abstract: |
| Title: The Effects of Projection on Iterative Methods in Image Deblurring |
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| Undergraduate Honors Thesis Defense: N/A |
| Speaker: James Herring of Emory University |
| Contact: Jim Nagy, |
| Date: 2010-04-02 at 4:00PM |
| Venue: MSC W303 |
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| Abstract: Applications of iterative regularization methods encompass a broad spectrum, including image deblurring. One unique feature in image deblurring problems is the non-negativity of the solution. In light of this knowledge, this thesis explores the effectiveness of three projected iterative methods for image deconvolution: projected successive over-relaxation method(SOR), projected Landweber method, and an interior point gradient method. Specifically, this thesis compares the effectiveness of these methods to the standard un-projected SOR method, comparing quality of image reconstruction and the cost of each method. The thesis begins with an introduction to the field of image deblurring problems, iterative regularization, and the methods tested, and follows with experiments and analysis designed to determine the usefulness of these methods for image deblurring. |
| Title: The Challenge of QoS in Configurable Mesh Networks |
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| Colloquium: Computer Science |
| Speaker: Nadine Shillingford of Notre Dame University |
| Contact: Susan Guppy, sguppy@emory.edu |
| Date: 2010-03-29 at 4:00PM |
| Venue: MSC W301 |
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| Abstract: QoS support for power-constrained wireless mesh networks (WMNs) poses a significant challenge. WMNs are increasingly used as multi-purpose networks, i.e., they serve multiple objectives and different applications simultaneously. As a consequence, a one-size-fits-all routing solution is difficult to achieve, particularly when the performance and QoS expectations of these applications differ. This talk discusses Configurable Mesh Routing (CMR), a toolkit that supports the discovery and management of routes based on any combination of a number of supported QoS metrics. This enables network users to deploy customized routes that meet their unique needs. |
| Title: Bubblesort and Juggling Sequences |
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| Colloquium: N/A |
| Speaker: Ron Graham of University of California San Diego |
| Contact: Vojtech Rodl, rodl@mathcs.emory.edu |
| Date: 2010-03-25 at 4:00PM |
| Venue: MSC W201 |
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| Abstract: In this talk I will describe some recent results concerning the connection between the bubblesort sorting algorithm and certain integer sequences used to analyze various juggling patterns. The analysis leads to new results on the joint distribution of the descent and maximum drop statistics of a permutation, as well as a new class of identities for the classical Eulerian numbers. |
| Title: Merkurjev's Norm Principle |
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| Seminar: Algebra |
| Speaker: Jodi Black of Emory University |
| Contact: R. Parimala, parimala@mathcs.emory.edu |
| Date: 2010-03-23 at 4:00PM |
| Venue: MSC W303 |
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| Abstract: A classical result of Scharlau gives that $N_{L/k}(G_L(q_L)) \subset G_k(q)$ where $q$ is a quadratic form over a field $k$ of characteristic different from 2, $L$ is a finite extension of $k$ and $G_k(q)$ is the set of similarity factors of $q$ in $k$. If $D_k(q)$ denotes the set of values of $q$ in $k$, and $[D_k(q)]$ is the subgroup it generates in $k$, another classical result, this time due to Knebusch, gives $N_{L/k}(D_L(q_L)) \subset [D_k(q_k)]$. In a 1993 paper, Gille proved a norm principle which generalized that of Knebusch and also implied a partial version of Scharlau's norm principle. Then in 1996, Merkurjev proved a norm principle which implied Gille's norm principle. Gille considered a $k$-isogeny of semisimple algebraic groups $1 \rightarrow \mu \rightarrow G^{\prime} \rightarrow G \rightarrow 1$ over a field $k$ of characteristic 0. He showed that the norm of the image of $RG(L)$ in $H^1(L,\mu)$ under the usual connecting map, is in the image of $RG(k)$ in $H^1(k,\mu)$ where $RG(k)$ is the set of elements of $G(k)$ $R$-equivalent to 1. Merkurjev considered short exact sequences $1 \rightarrow G_1 \rightarrow G \rightarrow T \rightarrow 1$ where $G_1$ and $G$ are connected reductive groups and $T$ is an algebraic torus defined over a perfect field $k$. He showed that the norm of the image of $RG(L)$ in $T(L)$ is in the image of $RG(k)$ in $T(k)$. We will discuss Gille and Merkurjev's norm principles and show how they imply at least partial versions of the previous results. Then we will illustrate how Merkurjev used his norm principle to give an explicit description of the image of $RG(k)$ in $T(k)$ and give that description in some specific examples. |
| Title: Distances in Permutations |
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| Seminar: SIAM Student Chapter |
| Speaker: David Gunderson of University of Manitoba |
| Contact: Votjech Rodl, rodl@mathcs.emory.edu |
| Date: 2010-03-22 at 4:00PM |
| Venue: MSC W303 |
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| Abstract: Given a permutation $S$ on $\{1,2,\ldots,n\}$, define its distance set to be $\{|S(i+1)-S(i)|: i=1,\ldots,n-1\}$. For example, when $n=5$, the permutation $(S(1),\ldots,S(5))=(5,1,4,2,3)$ has distance set $\{1,2,3,4\}$, however the permutation $(1,2,3,4,5)$ has distance set $\{1\}$. On average, how large is a distance set of a random permutation? If this expected number of distances is denoted $E_n$, the ratio $E_n/(n-1)$ approaches a limit. What is it? \\ \\ The questions above were loosely motivated by random considerations regarding the graceful tree conjecture and graceful colourings of paths. |
| Title: Scalable Data Services for Data-Intensive Computing Environments |
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| Seminar: Computer Science |
| Speaker: Patrick Widener, Ph.D. of Center for Comprehensive Informatics Emory University |
| Contact: Li Xiong, lxiong@mathcs.emory.edu |
| Date: 2010-03-19 at 3:00PM |
| Venue: MSC W301 |
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| Abstract: Future I/O systems for increasingly data-intensive computing environments face a challenging set of requirements. Data extraction must be efficient, fast, and flexible; on-demand data annotation -- metadata creation and management -- must be possible without modifying application code; and data products must be available for concurrent use by multiple downstream applications (such as visualization and storage), requiring consistency management and scheduling. In this talk, I will present a collection of techniques designed to address these challenges by decoupling data operations in space and in time from core application codes. Our research results show that these techniques can extract data efficiently and without perturbing compute operations, that they can be used to perform application-specific transformations while maintaining acceptable I/O bandwidth and avoiding back-pressure, and that they can decouple "in-band" and "out-of-band" processing to improve overall I/O performance. Bio: Patrick M. Widener is a Senior Research Scientist in the Center for Comprehensive Informatics and Research Assistant Professor in the Department of Biomedical Engineering at Emory University. His research interests include experimental systems, I/O and storage software for large-data environments, middleware, and the generation and use of metadata. Dr. Widener received his Ph.D. in Computer Science from the Georgia Institute of Technology in 2005, and prior to beginning his Ph.D. studies he was employed as a software developer by several companies which no longer exist. He also holds a Master of Computer Science degree from the University of Virginia (1992), and a Bachelor of Science in Computer Science from James Madison University (1990). |
| Title: Extremal problems for random discrete structures |
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| Colloquium: Combinatorics |
| Speaker: Mathias Schacht of University Hamburg |
| Contact: Vojtech Rodl, rodl@mathcs.emory.edu |
| Date: 2010-03-16 at 4:00PM |
| Venue: MSC W301 |
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| Abstract: We study thresholds for extremal properties of random discrete structures. We determine the threshold for Szemeredi’s theorem on arithmetic progressions in random subsets of the integers and its multidimensional extensions and we determine the threshold for Turan-type problems for random graphs and hypergraphs. In particular, we verify a conjecture of Kohayakawa, Luczak, and Rodl for Turan-type problems in random graphs. Similar results were obtained by Conlon and Gowers. |