BEGIN:VCALENDAR CALSCALE:GREGORIAN METHOD:PUBLISH PRODID:-//appliedmath.arizona.edu//NONSGML iCalcreator 2.2// VERSION:2.0 X-WR-CALNAME:UA Applied Math Events X-WR-CALDESC:Events Calendar, University of Arizona Program in Applied Math ematics X-WR-TIMEZONE:US/Arizona BEGIN:VTIMEZONE TZID:US/Arizona BEGIN:STANDARD DTSTART:19700101T000000 TZOFFSETFROM:-0700 TZOFFSETTO:-0700 TZNAME:MST END:STANDARD END:VTIMEZONE BEGIN:VEVENT CATEGORIES:Special Events DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080519T130000 DURATION:PT3H LOCATION:Math 401N SUMMARY:Joseph P. Stover: PhD Final Oral Dissertation Defense UID:20080519T172633CEST-hprXCb8hfC@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Special Events DESCRIPTION:10:00\nJohn Pate\n(Advisor: Juan Restrepo):\n''Asymptotic & Nu merical Analysis of Brillouin Precursors in Lorentz Media''\n\n\n10:30\nDa rin Comeau\n(Advisor: Shankar V.):\n''The Mechanics of Euler's Disk''\n\n \n11:00\nKevin LaTourette\n(Advisor: Juan Restrepo):\n''A comparison of t he Levenberg-Marquardt method with standard optimization algorithms\, in m inimizing the Tikhonov-Total Variational functional''\n\n\n11:30-11:45\n'' Break'' \n\n11:45\nChris Rainey\n(Advisor: Shankar V.):\n''A Derivation o f the Nonlinear Schrödinger Equation''\n\n\n12:15\nDavid Lyttle\n(Advisor : Hermann Flaschka):\n''Stochastic Resonance in Neurobiology''\n\n\n12:45- 2:00\n''Lunch Break''\n\n2:00\nBole Yang\n(Advisor: Hermann Flaschka):\n'' LRD of the fractional Brownian motion and the application in data network' '\n\n\n2:30\nRebecca Stockbridge\n(Advisor: Hermann Flaschka):\n''The Disc rete Binomial Model for Option Pricing''\n\n\n3:00-3:15\n''Break''\n\n3:15 \nStuart Kent\n(Advisor: Hermann Flaschka):\n''Lagrangian Coherent Structu res: Generalizing Stable and Unstable Manifolds to Non-Autonomous Dynamica l Systems''\n\n\n3:45\nDavid Love\n(Advisor: Juan Restrepo):\n''A Brief In troduction to Parameter Estimation in the context of Parabolic PDEs''\n\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080516T100000 DURATION:PT6H LOCATION:Math 101 SUMMARY:1st Year Students: Term Paper Workshop UID:20080519T172633CEST-P2LXMvux2o@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:There is currently tremendous interest in geometric PDEs\, due in part to the geometric flow program used recently to solve the Poincare conjecture. Geometric PDEs also play an expanding role in many other appli cations\, such as understanding the gravitational wave models of Einstein. The need to validate these models has led to the construction of gravitat ional wave detectors in the last several years\, such as the NSF-funded LI GO project. In this lecture\, we consider the coupled nonlinear elliptic c onstraints in the Einstein equations\, a geometric flow which describes th e propagation of gravitational waves generated by collisions of massive ob jects such as black holes. The constraint equations must be solved numeric ally to produce initial data for gravitational wave simulations and to enf orce the constraints during dynamical simulations. In the first part of th e lecture\, we consider a thirty-year-old open question involving existenc e of solutions to the constraint equations on space-like hyper-surfaces wi th arbitrarily prescribed mean extrinsic curvature\, and we give a partial answer using a priori estimates and a new type of topological fixed-point argument.\n\nIn the second part of this lecture\, we develop some adaptiv e numerical methods for which we can prove a number of useful results on c onvergence\, optimality\, and scalability. Based on the a priori estimates developed in the first part of the talk\, we first establish some critica l discrete estimates. We then derive error estimates for Galerkin approxim ations and describe a class of nonlinear approximation algorithms based on adaptive finite element methods (AFEM). We establish some new AFEM conver gence and optimality results for geometric PDE problems with non-monotone nonlinearities such as the Einstein constraints.\n\nWe finish by illustrat ing the algorithms with some examples using the Finite Element ToolKit (FE TK).\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080502T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Michael Holst: Some New Existence Results for a Geometric PDE Arisi ng from General Relativity and an Approximation Theory Framework UID:20080519T172633CEST-57b2StnUAw@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Brown Bag DESCRIPTION:In this talk\, we will present some of the basic notions of con trollability and optimality of affine control systems subject to a payoff functional. We will illustrate these ideas by studying control systems tha t model physical devices such as rocket-powered cars\, springs\, etc. In p articular\, we will present our recent results in how to parallel park a b ike in the least amount of time\, subject to the constraint that the bike' s wheels rotate at a fixed speed.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080502T120000 DURATION:PT1H LOCATION:Math 402 SUMMARY:John Gemmer: How to Control a Front-Wheel-Drive Bike UID:20080519T172633CEST-dWw7zSDK0I@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:We propose a simple spatio-temporal marked Poisson point proces s to describe the large structure of breaking waves in the ocean. The brea king events are 'marked' with the associated local energy drop. This model is suitable for estimating dissipation at large scales (ocean currents) i nduced by small-scale events (waves breaking). Finally I will use a Gaussi an model for the sea surface to calculate some notions of the probability of wave-breaking and the distribution of the associated energy drop. This is joint work with Juan Restrepo. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080501T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Jorge Ramirez: Large-Scale Stochastic Modeling of Oceanic Wave-Brea king UID:20080519T172633CEST-NVVkR3wX8b@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080430T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Ed Kerschen: Research problems in aero-acoustics UID:20080519T172633CEST-R4OtUAHj3S@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:SIAM Event DESCRIPTION:We study the polyhedral structure of the uncpacitated single-it em lot-sizing problem with backlogging. We give an explicit linear descrip tion of the convex hull of solutions to this problem in its natural space of production\, setup\, inventory\, and backlogging variables. We describe a separation linear program for our proposed inequalities as well as the first exact combinatorial separation algorithm for a well-known special ca se. To illustrate the effectiveness of our inequalities\, we report a summ ary of computational experiments with a branch-and-cut algorithm on a clas s of NP-hard multi-item lot-sizing problems. Finally\, we show that our re sults can be generalized to give strong inequalities for uncapacitated fix ed-charge network flow polyhedra that arise in distribution planning probl ems. \n\nLunch/refreshments provided. \n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080430T130000 DURATION:PT1H LOCATION:Math 401N SUMMARY:Simge Kucukyavuz: Mixed-Integer Optimization for Production and Dis tribution Planning Problems UID:20080519T172633CEST-Cm33KbuvX2@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:Assembly of molecular specializations in cell membranes clearly involves signaling. Examples include neural synapses\, immunological syna pses\, and cell surface adhesion structures. But HOW does the signaling ge t translated into the formation of large-scale molecular structures? Also\ , the resulting structures must be quasi-stable\, accommodating the incess ant turnover of cell surface molecules while retaining characteristic size s and substructure over years\, potentially.\n\nI present multiple models that generate molecular assemblies with remarkable similarities to those s een in biological systems. Successful models are self-organizing and invol ve coupled state transitions. Rich structures result even from the self-or ganization of a single type of molecule. The use of multiple models helps to identify specific properties that underlie aspects of the biology. For example\, the perforation of synapses from central and peripheral nervous systems and even including immunological synapses can result from the sele ctive turnover of anchored molecules within the synapses.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080429T161500 DURATION:PT1H LOCATION:Keating 103 SUMMARY:Herman Gordon: Multiple Models of Molecular Assembly at Synapses UID:20080519T172633CEST-rixVP4VZKT@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:The Evans function is an analytic function that can be used to investigate the spectral stability of one-dimensional localized solutions to nonlinear PDEs. It is defined in such a way that its zeros on the right complex plane are eigenvalues of the corresponding linearized operator. T he Evans function is a Wronskian-like function and can in principle be eva luated by a shooting method. In this situation\, however\, numerically eva luated solutions corresponding to linearly independent initial conditions tend to become linearly dependent\, which may lead to spurious zeros of th e Evans function. I will argue that for localized solutions that are suffi ciently narrow\, it is possible to accurately compute the Evans function u sing a shooting method.\n\nAs an example\, I will consider the spectral st ability of a two-parameter family of traveling wave solutions to two coupl ed nonlinear Klein-Gordon equations. These are envelope equations that mod el the dynamics of small deformations of an elastic rod near a writhing bi furcation. Numerical results are in agreement with analytical results obta ined by S. Lafortune and J. Lega.\n\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080429T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Silvia Madrid-Jaramillo: Numerical computation of the Evans functio n with application to the stability of small deformations of an elastic ro d UID:20080519T172633CEST-mLrkfsEA3k@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:Typical porous media processes are affected by heterogeneities at different length scales. In this talk\, I will describe multiscale fini te element methods for flow and transport in heterogeneous porous media. T he main focus of the talk is on subgrid capturing using various local and global methods.\n\nI will discuss the use of local boundary conditions and the use of global information in capturing subgrid effects. The upscaling of the transport equation and its coupling to the flow equation will be p resented. The mathematical analysis of these methods will be discussed.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080425T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Yalchin Efendiev: Multiscale Numerical Methods for Flow and Transpo rt in Heterogeneous Porous Media and Their Applications UID:20080519T172633CEST-6t7mUbxD0W@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:Otoacoustic emissions (OAEs) are sounds generated and subsequen tly emitted by a healthy ear (detectable using a sensitive microphone) whi ch appear in a wide range of vertebrate species. While the exact generatio n mechanisms remain unclear\, OAEs evoked using an external stimulus exhib it significant group delays across a wide frequency range\, on the order o f 1-2 ms or greater. In mammals such as humans\, these delays are generall y thought to arise due to the presence of cochlear traveling waves. Howeve r\, in classes such as lizards\, such waves are noticeably absent. The pre sent study hypothesizes that these delays are in fact associated with the sharp tuning manifested in the auditory periphery and represent the build- up time of highly tuned coupled oscillators. Preliminary model results for the gecko ear show remarkable agreement with empirical data and predict t hat emission group delays increase with increasing sharpness of tuning (as typically measured via auditory nerve fiber responses). DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080424T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Christopher Bergevin: Modeling Otoacoustic Emission Group Delays in the Lizard Auditory Periphery UID:20080519T172633CEST-BtvsA0rBFU@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080423T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Ed Kerschen: Research problems in aero-acoustics UID:20080519T172633CEST-hvkrEfH9e9@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:SIAM Event DESCRIPTION:The history of superconductivity has been referred to as the hi story of quantum mechanics. Following the first observation of the phenome non in 1911\, it took nearly five decades to arrive at the now-famous Bard een-Cooper-Schrieffer (BCS) theory of 'low Tc' superconductivity. Even mor e person-years have\, however\, gone into research on the mechanism of 'hi gh Tc' superconductivity\, which was discovered in 1986\, and about which there is no consensus to date.\n\nIn the first part of this talk I will br iefly discuss the surprises and challenges that make the high Tc problem s uch a formidable one. The difficulty arises not merely in the high critica l temperatures of the superconductors but also in the dominant repulsive i nteraction among the charge carriers\, which make the simple BCS theory in applicable to these systems. Following this\, I will point out that there is now general agreement that similar repulsive interactions characterize many other unconventional superconductors\, and there exists therefore an entire class of systems that lie outside the scope of the BCS theory. I wi ll then focus on one such family of materials\, organic charge-transfer so lids\, and discuss our recent advances towards understanding the mechanism of superconductivity in these. It is conceivable that this particular mec hanism is applicable to correlated electron superconductors in general. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080423T130000 DURATION:PT1H LOCATION:Math 401N SUMMARY:Sumit Mazumdar: Repulsive Coulomb Interactions and Unconventional S uperconductivity UID:20080519T172633CEST-UVRu0uUg3S@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:We are developing methods for defining transcriptional regulato ry networks underlying fundamental processes during embryonic development. Our general approach is to create a preliminary structure network (PSN) u sing a variety of biological information stores\, to iteratively sample th is and modified networks across parameter space\, and then to test success ful networks in vivo. A primary limitation for generation and modification of the PSN is the relative lack of interaction data in most model organis ms\, including chicken. To overcome this problem\, we have created integra ted interolog (interaction homolog) networks for all organisms represented in NCBI’s HomoloGene database using all available interaction data. This has greatly increased the amount of interaction data available for th e twenty organisms currently in HomoloGene. We have also developed new alg orithms for more rapidly sampling networks in topology space and for measu ring their robustness with respect to changes in reaction rates. To measur e robustness efficiently\, we use approximations to the ODE systems that a re valid in a neighborhood\, and use the fact that re-optimizing is much l ess expensive than optimizing from scratch. Our methods are related to Mar kov Chain Monte Carlo sampling and Trust Regions. Preliminary results indi cate an improvement of an order of magnitude in terms of computing time\, with only a marginal increase in variance. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080422T161500 DURATION:PT1H LOCATION:Keating 103 SUMMARY:Parker Antin\, Departments of Cell Biology and Anatomy and Molecula r and Cellular Biology\, and Leo Lopes\, Department of Systems and Industr ial Engineering: Network Modeling of Gene Regulatory Pathways in Vertebrat e Development UID:20080519T172633CEST-2ozL6kR646@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:After reviewing some more examples of topological groupoids\, I will present the notion of groupoid action on a topological space. This c an then be generalized to groupoid actions on C*-algebras. I will end up w ith a discussion of the tangent groupoid\, its associated C*-algebra\, and their use in index theory. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080422T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Dorin Dumitrascu: Groupoid Actions on C*-algebras\, Part II UID:20080519T172633CEST-3tH0rLvuZX@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:(This colloquium has been canceled.)\n\nSince the development a nd commercialization of the first nematic liquid crystal display devices i n the middle of the last century\, mathematical modeling and analysis of l iquid crystals has experienced significant progress. Liquid crystals are p hases intermediate between solid and liquid\; they occur in synthetic as w ell as in organic compounds. The Kevlar fiber is an example of a highly em ployed liquid crystal polymer\; many virus and bacteria colonies as well a s biological tissues present liquid crystal ordering.\n\nLiquid crystals o f small molecular weight consist of rigid\, rod-like molecules that tend t o follow preferential directions of alignment. Their interaction with elec tric and magnetic fields is at the core of application to display devices. Recently developed liquid crystals exhibit more complicated molecular sha pes able to sustain permanent dipoles that result in ferroelectric couplin g with applied electromagnetic fields. The speed of switching of such devi ces is about 10^3 to 10^4 times that of the nematic cell. Equilibrium stat es of ferroelectric liquid crystals result from minimizing the total energ y subject to packing and electrostatic constraints. I will present an appl ication of such a theory to predicting shape of material filaments.\n\nLiq uid crystal elastomers are nonlinear elastic solids that may also present liquid crystal phases. One remarkable feature is their capability to under go unusually large deformations along preferential directions. Upon analyz ing mathematical issues of such models\, I will address their gel states a nd discuss the potential matrix role in modeling cell motility in the brai n.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080418T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Maria-Carme T. Calderer: [CANCELED] Elastic and Ferroelectric Prope rties of Liquid Crystals: Modeling and Analysis UID:20080519T172633CEST-ZZTkDSbcE7@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Brown Bag DESCRIPTION:Spatial patterns are commonly observed among dispersing populat ions in nature. When stored in a homogenous flour medium\, the larval and adult stages of the flour beetle Tribolium brevicornis will spatially segr egate. In this talk we explore stage-structured integro-difference equati on models with density-dependent dispersal kernels through mathematical an alysis. We will also use computer simulations to investigate the mathemat ical mechanisms that lead to spatial patterns such as those observed in T. brevicornis. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080418T120000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Suzanne Robertson: Spatial Patterns in Stage-structured Populations with Density-Dependent Dispersal UID:20080519T172633CEST-zxgNSuUaVR@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:Particle Filters are sample-based numerical methods for the dis crete-time Filtering Problem. These methods suffer from large operations c ount and troubles defining prediction. This work introduces a particle fil ter method for the discrete-time Filtering Problem with SODEs\, along with a suitable definition of prediction. The method\, to be called Diffusion Kernel Filter\, applies when the dynamics of the SODE develops few moments (i.e.\, is weakly nonlinear) on ``branches of prediction'' between the fi ltering times (which is expected to be the case in several applications in the geosciences) and is arrived at by a parametrization of small fluctuat ions of Wiener-driven paths about deterministic paths and a local use of t his parametrization in the referential Bootstrap Filter.\n\nThe parametriz ation is derived by reformulation of the SODE problem into a Liouville SPD E problem\, application of Duhamel's principle to this problem\, restricti on of the resulting to nonlinear SODE open problems for the flows of ``bra nches of prediction\,'' closure of these. This was inspired by Chorin's `` Optimal prediction with memory\,'' where a similar technique is used to ta ckle the dimension reduction problem for the dynamics of a nonlinear ODE. Results obtained with the early Lorenz equations and a set of equations of point-vortex interactions are presented.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080417T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Paul Krause: The Diffusion Kernel Filter UID:20080519T172633CEST-VWWM7HVR5v@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080416T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Joanna Masel: Prions and population genetics UID:20080519T172633CEST-uXPaxrJnIT@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Special Events DESCRIPTION:Roald Sagdeev has made significant contributions to modern plas ma theory\, including the areas of collisionless shocks\, stochastic magne tic fields\, ion temperature gradient instabilities\, quasi-linear theory\ , neoclassical transport\, and weak turbulence theory. He is the former di rector of the Russian Space Research Institute\, the Soviet equivalent of NASA\, and he was also a science advisor to Mikhail Gorbachev. He is a mem ber of the Russian Academy of Sciences. He has received many awards and is a member of many other national academies including the Vatican Academy o f Sciences. Since 1989 he has been working at the University of Maryland w here he is a Distinguished University Professor.\n\nFor a complete schedul e please see the website for the workshop\, at http://math.arizona.edu/~nr w/MiniWorkshop2008.html DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080416T120000 DURATION:PT4H LOCATION:Math 402 SUMMARY:Roald Sagdeev\, University of Maryland\; Pierre Deymier\, Alan Newe ll\, and Vladimir Zakharov\, The University of Arizona: Miniworkshop on Wa ves in Plasmas\, Oceans\, and Metamaterials UID:20080519T172633CEST-3Cao4xxnur@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:Adiponectin is a signalling hormone which stimulates the body's response to insulin and is of interest as a possible therapeutic for diab etes. Detailed knowledge of adiponectin's three-dimensional structure is p rerequisite to a mechanistic understanding of its physiological role. Howe ver\, its biochemical properties preclude the use of conventional experime ntal structure-determination methods. In this talk we will show how to dev elop new methods\, based on the differential geometry of curves\, to model the structure and mechanics of proteins. These methods are particularly w ell-suited to explore the properties of helical assembly. Starting with si mple helical structure (coils) we will show how we can construct higher-or der assemblies such as the ubiquitous coiled-coils\, a protein motif found in many fibrous proteins. The mechanical properties of such assemblies ca n be determined by developing a multiscale theory. The next higher-order a ssembly is the coiled-coiled-coil\, which we believe is applicable to adip onectin\, since it exists in serum in three distinct oligomeric states wit h 3\, 6\, and 18 protein subunits. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080415T161500 DURATION:PT1H LOCATION:Keating 103 SUMMARY:Andrew Hausrath\, Department of Biochemistry and Molecular Biophysi cs\, and Alain Goriely\, Department of Mathematics: Coils\, Coiled-coils\, and Coiled-coiled-coils: Unraveling the Hierarchical Structure of Adipone ctin UID:20080519T172633CEST-Ku13Ub8PH4@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:The main goal of the talk is to discuss the notion of groupoid action on a C*-algebra and point out some of the difficulties that one has to deal with. I will use two examples to show the usefulness of groupoids . The first is the characterization of an AF algebra as the C*-algebra of a principal groupoid\, and the second is the use of the tangent groupoid i n index theory. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080415T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Dorin Dumitrascu: Groupoid Actions on C*-algebras UID:20080519T172633CEST-6ndhUbi0NM@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:(This week's colloquium has been canceled.)\n\nWe study the spe ctrum of a linear advection-diffusion equation in a periodic domain\, wher e the diffusion coefficient changes its sign. We prove that the spectrum o f an associated linear operator consists of an infinite set of simple eige nvalues on the imaginary axis and the set of corresponding eigenfunctions is complete. However\, we also show\, assisted with numerical approximatio ns\, that the complete set of linearly independent eigenfunctions does not form a basis in a space of square integrable functions and that the Cauch y problem for the advection-diffusion equation is ill-posed. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080411T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Dmitry Pelinovsky: CANCELED: Advection-Diffusion Equations with For ward-Backward Diffusion UID:20080519T172633CEST-sWKX7Lj376@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Brown Bag DESCRIPTION:In developing software for scientific computation\, one has typ ically been forced to choose between the fast development but slow program execution associated with high-level programming languages and the fast e xecution but slow development associated with low-level languages like FOR TRAN. Another alternative has been the use of commercial software such as MATLAB (R) or Mathematica (R)\, but these applications are expensive and c losed-source\, thereby inhibiting sharing and collaboration with those por tions of the scientific community who can't afford these applications. Suc h commercial codes are also highly specialized\, making it difficult to ex tend them to wider problem domains.\n\nThe recent arrival of the SciPy pac kage of high-level scientific computation modules for the Python programmi ng language allows for the development of scientific computations sufferin g from none of these drawbacks. Python is a very high-level language\, all owing for extremely rapid development of robust and sophisticated software . The speed-critical components of SciPy (linear algebra\, FFTs\, numerica l quadrature\, etc.) are called from within Python but are implemented in FORTRAN or C\, enabling rapid execution speed. Furthermore\, all of Python and SciPy are completely free and open-source\, enabling scientific codes developed in Python to be distributed freely. And by using Python to deve lop scientific computations\, one has access to a huge library of other ge neral functionality\, enabling for example easy development of software th at has sophisticated graphical user interfaces (GUIs) and interfaces with databases\, or that uses the internet to send e-mail or retrieve data.\n\n The talk will provide a brief high-level overview of the Python programmin g language\, followed by several examples of the ease with which powerful scientific computations can be performed using SciPy. Examples will includ e image processing\, signal processing\, solution of PDEs using sparse mat rix solvers\, advanced scientific visualization\, and interactive distribu ted and parallel supercomputing. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080411T120000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Robert G. Erdmann: Python for Scientific Computing UID:20080519T172633CEST-Fhsxm1TMjN@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:Red blood cell movement\, deformation\, and partitioning in sma ll diverging microvessel bifurcations are simulated using a two-dimensiona l\, flexible-particle model. For isolate red blood cell movement\, while s imulated red blood cell trajectories tend to follow background fluid strea mlines\, significant deviations from these streamlines can occur because o f red blood cell migration towards vessel centerlines and red blood cell o bstruction of downstream vessels. The net effect of these behaviors is exp lored in symmetric and asymmetric vessels to produce results comparable wi th experiment. In addition\, preliminary results and insights are presente d for multiple red blood cell motion in straight vessels and in bifurcatio ns. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080410T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Jared Barber: Two-Dimensional Model of Red Blood Cell Motion in Mic rovessels UID:20080519T172633CEST-2hfb9G3ACv@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080409T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Joanna Masel: Prions and population genetics UID:20080519T172633CEST-VXMD6JkFgi@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:In 1973 Karl von Frisch was awarded the Nobel Prize in Physiolo gy for his work decoding the 'language' of bees. The language of bees\, a lso known as the 'waggle dance\,' is used by foraging honeybees to indicat e the distance and direction of a food source to other bees in the hive. S ince then we have learned from numerous behavioral studies that a honeybee 's judgment of distance is based on a visual estimate of speed. This estim ate is relatively independent of spatial frequency\, contrast\, and direct ion of motion and can even be made with only monocular input.\n\nDespite o ur thorough understanding of the many behaviors that rely on visual speed estimation\, we still lack a solid understanding of the underlying neural processes responsible for the estimate. My research has focused on evaluat ing various models of visual speed estimation based on their effectiveness for replicating\, in simulation\, the behaviors observed in honeybees. I then use the results from the simulations to generate hypotheses and exper iments to further refine the models. In addition\, I have recently begun m y own behavioral work to gather more detailed information on the propertie s of the honeybee speedometer.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080408T161500 DURATION:PT1H LOCATION:Keating 103 SUMMARY:Jonathan Dyhr: Visual Speedometers in the Honeybee Brain UID:20080519T172633CEST-5LgXdZ4w4V@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:One of the commonly used equations describing nematic liquid cr ystals is the so-called Doi-Smoluchowski equation. In essence\, it is a ki netic equation for evolution of the orientation probability density of the system. I will present an analogue of this equation for spatially inhomog eneous systems and will discuss the associated problems of moment closure and reduction to Ginzburg-Landau type dynamics. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080408T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Ibrahim Fatkullin: Diffusive Transport in Nematics UID:20080519T172633CEST-8smJUZ7VtW@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:I will develop and analyze stochastic models for two \nimportan t processes in cellular biophysics. The first problem concerns mRNA transl ation and protein production\, and is modeled as an interacting particle s ystem in 1D. The effects of 'slow codons\,' or defects in the mRNA\, on pr otein production rates are addressed by asymptotic matching of mean-field solutions of the problem. In the second problem\, a stochastic model for v iral entry into cells is developed. The entry of viruses turns out to be a competition between \nmembrane fusion and endocytosis. The probabilities for entry via each of these pathways are calculated within one- and two-su rface receptor models. Conditions for endocytosis are mapped. Time permitt ing\, I will also briefly introduce a stochastic inverse problem where tra nsition rates of a Markov process can or cannot be reconstructed from firs t \npassage time distributions.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080404T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Tom Chou: Stochastic Models in Biophysics UID:20080519T172633CEST-UM1GbIcRrE@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Brown Bag DESCRIPTION:Detonation is a combustion-driven supersonic shock wave that ca n reach speeds of several kilometers per second. Applications range widely \, from jet propulsion to the theory of supernova explosions. In our work we investigate the linear stability and receptivity of the Zel'dovich-von Neumann-Doering (ZND) detonation wave model. The solution of the initial-v alue problem for small three-dimensional perturbations in a ZND detonation is presented as an expansion into modes of discrete and continuous spectr a. The result provides a tool to predict initial amplitudes of the unstabl e modes depending on the initial perturbation. The results for different t ypes of introduced perturbations are discussed. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080404T120000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Carlos Chiquete: Receptivity of Plane Idealized One-reaction Detona tion to Three-dimensional Perturbations UID:20080519T172633CEST-hiut0wDPT1@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:In this talk\, we first discuss simulation-based shop floor pla nning and control\, where 1) on-line simulation is used to evaluate decisi on alternatives at the planning stage\, 2) the same simulation model (exec uting in the fast mode) used at the planning stage is used as a real-time task generator (real-time simulation) during the control stage\, and 3) th e real-time simulation drives the manufacturing system by sending and rece iving messages to an executor (Finite State Automata). We then discuss how simulation-based shop floor planning and control can be extended to enter prise level activities (top floor). To this end\, we discuss the analogies between the shop floor and top floor in terms of the components required to construct simulation-based planning and control systems such as resourc e models\, coordination models\, physical entities\, and simulation models . Differences between them are also discussed in order to identify new cha llenges that we face for top floor planning and control. A major differenc e is the way a simulation model is constructed so that it can be used for planning\, depending on whether time synchronization among member simulati ons becomes an issue or not. We also discuss the distributed computing pla tform using web services and grid computing technologies\, which allow us to integrate simulation and decision models\, and software and hardware co mponents. Finally\, we discuss other emerging applications for the propose d simulation-based planning and control\, such as emergency evacuation and blood supply network. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080403T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Young-Jun Son: Distributed Federation of Multi-paradigm Simulations and Decision Models for Planning and Control: From Shop Floor to Top Floo r UID:20080519T172633CEST-CfHL54GUBc@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080402T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Pierre Deymier: Research problems in Materials Science UID:20080519T172633CEST-ZnP2hVhRWx@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:I will talk about the regularity properties of the free boundar y for the Stefan problem\, which models the phase transition between solid s and liquids\, and will present a recent work: If the initial free bounda ry is Lipschitz with a small Lipschitz constant\, then the weak (viscosity ) solution of the one-phase Stefan problem immediately regularizes and is smooth in space and time\, for a small positive time. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080401T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Sunhi Choi: Free Boundary Regularity for the Stefan Problem UID:20080519T172633CEST-ouzUuNOjG8@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:Al Scott Lecture. The ability of the circulatory system to adeq uately match blood supply to tissue demand implies the existence of regula tory mechanisms that communicate tissue status to blood vessels. For examp le\, red blood cells have been shown to respond to low tissue oxygen level s by releasing ATP. The ATP triggers a conducted response signal to travel upstream and cause arterioles to dilate so that more blood is delivered t o the region of demand. A theoretical model focusing on the role of this m echanism in blood flow regulation is presented here. In the model\, arteri oles control blood flow by dilating or constricting in response to changes in metabolism as well as to changes in pressure and wall shear stress. Th e model predicts that responses to these three stimuli can account for the increase in blood flow that occurs with increased oxygen demand. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080328T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Julia Arciero: Theoretical Model of Metabolic Blood-flow Regulation UID:20080519T172633CEST-d1TT8DUesP@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Brown Bag DESCRIPTION:In many cylindrical structures in biology\, residual stress fie lds are created through differential growth. In particular\, if the outer and inner layers of a cylinder grow at different rates\, parts of the cyli nder will be in a state of axial compression and other parts will be in te nsion. These tissue tensions play a fundamental role in the overall rigidi ty and stability of the cylinder. Here\, we present an analysis based on n onlinear elasticity to study the effect of tissue tension on the mechanica l properties of growing cylinders and we reveal a subtle interplay between geometry\, growth\, and nonlinear elastic responses that help us understa nd some of the remarkable properties of stems and other biological tissues . DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080328T120000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Rebecca Vandiver: Tissue Tension and Axial Growth in Cylindrical El astic Structures UID:20080519T172633CEST-EwXCvV6NPk@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:The remarkable functional versatility of proteins is made possi ble by the diverse array of three-dimensional folds that they adopt. The c onventional representation of protein structure is a discrete coordinate m odel listing the positions of all atoms in the structure. While this repre sentation is very useful for understanding intricate chemical details\, it is not well suited to addressing more general questions about the nature of protein folds\, their variability\, and the relationships between them. To investigate such questions\, we have developed a continuous representa tion of proteins based on the geometry of space curves. The description of a protein fold in terms of its underlying geometry has proved to be much more efficient than the coordinate representation\, suggesting that sparse experimental data may be sufficient to restrain a curve model where a con ventional coordinate model would be underdetermined. Many proteins are not amenable to high-resolution structural analysis\, and for these challengi ng cases it is important to make the best use of the limited experimental information available. The talk will describe the application of the curve representation to diffraction techniques focusing in particular on low-re solution X-ray crystallography.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080327T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Andrew Hausrath: Applications of Geometry in Protein Structure Anal ysis UID:20080519T172633CEST-DT2KF5OFWi@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080326T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Pierre Deymier: Research problems in Materials Science UID:20080519T172633CEST-J9ZFmv8HgK@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:I will start with examples of models that describe collective b ehaviors in animal herds\, fish schools\, and bird flocks\, and explain ho w some of these ideas can be extended to describe the dynamics of bacteria l systems which do not communicate with one another. This will take us to problems related to the dynamics of gases\, such as for instance granular gases. In that context\, I will show simulations that explore the question of how the macroscopic behavior of a system of interacting particles can be affected by changing the collision rules between these particles. I wil l then explain how I think this could be related to the Lyapunov modes of the dynamics of the system. The structure of these modes has been widely s tudied in the literature and\, in particular\, the modes associated with s mall (in absolute value) Lyapunov exponents are known to have large-scale correlations. I will summarize the contents of a paper by Eckmann and Gat (J. Stat. Phys.\, 2000)\, which tries to explain this phenomenon by lookin g at the eigenvectors of a random matrix.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080325T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Joceline Lega: Collective Behaviors\, Lyapunov Modes\, and Random M atrices UID:20080519T172633CEST-NoHAFZzINR@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Brown Bag DESCRIPTION:Plyllotaxis\, namely the arrangement of phylla (leaves\, floret s\, etc)\nhas intrigued natural scientists for over four hundred years. Cu rrent\ntheories and models of the formation of phyllotactic patterns at th e plant\napical meristem focus on either transport of the growth hormone a uxin or the mechanical buckling of the plant tunica. Each of the mechanism s alone can give rise to an instability that leads to patterned states. Ho wever\, it is known that the two mechanisms interact with each other inste ad of acting independently. We (Alan C Newell\, Patrick Shipman\nand I) de velop a model that incorporates the coupling of biochemistry and mechanics . I will discuss the parameter choices under which the two mechanisms may cooperate in determining the pattern\, or under which one or the other mec hanism may dominate. Analysis of these equations shows that the coupling o f the two mechanisms acts like a\npositive-feed-back system and relaxes th e condition for primordium initiation.\n\nAlso\, on real plants\, the patt ern doesn't form all at once. Rather\, the primordia are formed sequential ly over time and gradually add to the existing pattern. Therefore\, betwee n the stable patterned state and the unstable non-patterned state\, there exists a front that propagates with some finite velocity into the non-patt erned state. I\nwill discuss how this idea of front propagation coincides with a well-accepted conceptual model for phyllotaxis proposed over a hund red years ago by Hofmeister and Snow&Snow. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080314T120000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Zhiying Sun: Phyllotactic pattern propagation UID:20080519T172633CEST-W6eiOspB1u@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:The simulation-based design of nonlinear systems is hampered by several hurdles such as high CPU times\, the difficulty to evaluate gradi ents\, and the acute sensitivity of responses to loading and design uncert ainties. In addition\, the system's responses might be discontinuous due t o the presence of numerous limit and bifurcation points. This considerably limits the blind use of traditional optimization and probabilistic method s. Typical examples of problems with discontinuous behaviors are structura l impacts and nonlinear aeroelasticity with limit cycle oscillations (LCO) .\n\nThis seminar will describe a methodology which facilitates the probab ilistic (optimal) simulation-based design of nonlinear problems. The appro ach\, referred to as explicit design space decomposition\, is based on dat a mining and machine learning techniques. The main feature of this approac h lies in the explicit definition of limit state functions (or constraints ) constructed from a design of experiments (DOE). A method to adaptatively update the limit state function and refine the DOE will be presented. \n\ nSeveral test examples will demonstrate the efficiency of the approach in the case of the reliability-based optimization of nonlinear structures and LCO problems. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080313T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Samy Missoum: Probabilistic Optimal Design for Highly Nonlinear Pro blems UID:20080519T172633CEST-4jg0GXjRr9@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080312T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Jean-Marc Fellous: Research Problems in Computational Neuroscience UID:20080519T172633CEST-ZZ8viPuvNR@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:SIAM Event DESCRIPTION:Interested in exploring career options outside of academia and national laboratories? Come participate in a panel discussion with mathema ticians who are successfully working in various industries and Ms. Levine\ , who directs the Professional Science Masters program and is a highly suc cessful entrepreneur and motivational speaker. And of course there will be food. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080312T130000 DURATION:PT1H LOCATION:Math 401N SUMMARY:Bob Breault (Breault Co.)\, Hyrum Cotrell (Edward Jones)\, Diana J. Kennedy (Raytheon)\, Alaina Levine (UA PSM)\, William Velez (US Navy\, UA Math)\, Olga Yiparaki (IBM): Finding and Getting Post-Graduation Industry Work: A Panel Discussion UID:20080519T172633CEST-1HliFpuuVh@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:Using the compiled human genome sequence\, we systematically ca talogued all tandem repeats with periods between 20 and 2\,000 bp and defi ned two subsets whose pattern sequences were found at either single (slTRs ) or multiple loci(mlTRs). Parameters compiled for these subsets are cons istent with a two step model for their evolution beginning with an initial duplication event insensitive to the unique or repetitive nature of the n ascent sequence. Subsequent amplification steps via gene conversion are in frequent and can create new alleles varying in both repeat number and inte rnal sequence. Tandem repeats are non-randomly distributed in the genome\ ; both subsets are found at higher frequency at many but not all chromosom e ends and internal clusters of mlTRs are also seen. Despite the integral role of recombination in the biology of tandem repeats\, recombination hot spots co-localized only with shorter microsatellites and not the longer re peats examined here. An increased frequency of slTRs was observed near imp rinted genes\, consistent with a functional role\, while both slTRs and ml TRs were found more frequently near genes implicated in triplet expansion diseases\, suggesting a general instability of these regions. Using our co llated parameters\, we identified 2\,230 slTRs as candidates for highly in formative molecular markers. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080311T161500 DURATION:PT1H LOCATION:Keating 103 SUMMARY:Vicki Chandler: Genome-Wide Analyses of Tandem Repeats in Humans UID:20080519T172633CEST-UMGGN3l6aO@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:In this talk I hope to explain the Deift-Zhou steepest descent method for oscillatory Riemann-Hilbert problems (RHPs)\, which can be thou ght of as a method analogous to the steepest descent method for obtaining asymptotic limits of integral expressions. The asymptotic limits I will co nsider come from RHPs associated with the nonlinear Schrodinger equation.\ n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080311T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Robert Jenkins: An Asymptotic Method for Riemann-Hilbert Problems UID:20080519T172633CEST-VDUBCjmVa3@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION: CANCELED DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080307T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Timothy J. Healey: CANCELED: Some Problems in Second-Gradient Nonli near Elasticity UID:20080519T172633CEST-oUElo5W0Zm@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Brown Bag DESCRIPTION:In this talk\, we present a stochastic shortest path problem th at we refer to as the Most Likely Path Problem. On a fairly general class of networks\, i.e.\, series-parallel networks\, we will show that lower an d upper bounds for the probability of the Most Likely Path (MLP) can be co mputed efficiently. We will then present a dynamic programming algorithm f or identifying the MLP on series-parallel networks. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080307T120000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Daniel Reich: The Most Likely Path UID:20080519T172633CEST-SWMpT0vokE@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:Tightly packed elastic structures can be found in a wide variet y of physical and biological systems. Traditionally mechanical and geometr ical aspects are treated separately due to the complex nature of the obser ved patterns (e.g.\, a piece of crumpled paper). We present a statistical field theory to study the packing of an elastic rod (1D) confined in 2D sp ace. An advantage of this approach is that it puts geometry and mechanics on an equal footing. We show that a self-reorganization of the rod becomes favorable at a critical density. This configurational phase transition (i sotropic-nematic) leads to a more efficient packing. For even higher confi nements we predict the existence of a jamming transition hinting at the gl assy character of this system. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080306T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Laurent Boue: A Statistical Physics Approach to Packing Problems UID:20080519T172633CEST-j7DwrdHVuu@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080305T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Walt Piegorsch: Interdisciplinary research problems in statistics UID:20080519T172633CEST-vPuGjkeFC3@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:The reality of global warming\, reflected in a broad spectrum o f climate system change\, is now unequivocal. Moreover\, human complicity in global warming has also been established beyond a reasonable doubt. Wit h these and other advances embodied in the Intergovernmental Panel on Clim ate Change Fourth Assessment Report (IPCC AR4) has come a shift in scienti fic focus toward efforts designed to improve our understanding of what wil l happen in the future\, and to what can be done to deal with the reality of global to regional climate change. Major efforts are now needed to deve lop strategies for adapting to climate change that is already in the pipel ine\, and also to identify climate changes that may be deemed unacceptable \, and thus worthy drivers of mitigation strategies designed to reduce the rate of atmospheric greenhouse gas increases to 'safe' levels.\n\nThere m ay be many aspects of future global climate change that will ultimately be deemed undesirable and worthy of mitigation efforts\, but two major issue s are already coming into focus. The first is global sea level rise couple d with increasing tropical storm intensities. There is no doubt that globa l sea level is rising\, and little doubt that the rates of sea level rise are likely to increase. In contrast to what some biased media and individu als are saying\, the IPCC AR4 did not lower estimates of future sea level rise. Indeed\, the most recent estimates suggest that 1m or more of sea le vel rise could occur by 2100\, as well as a commitment to a much larger se a level rise over subsequent centuries. The wildcard will be the future be havior of the large polar ice sheets\, and there is growing evidence that the ice sheets are more vulnerable to global warming than widely thought.\ n\nAlthough coastal areas could thus be big losers in the face of continue d climate change\, recent climate change coupled with climate change proje ctions indicate that the American West--including the alpine West--could b e a more near-term casualty. Surface air temperatures are already rising f aster than elsewhere in the coterminous United States\, and will likely co ntinue to rise steadily. These temperature increases are already causing s now to fall increasingly as rain\, and also to melt earlier in the year. T hus\, even in the absence of a precipitation decrease\, there will be less snow-related run-off and related surface water flow. This trend is also b eing exacerbated in some parts of the West by human-caused increases in at mospheric dust loading. Unfortunately\, nearly all state-of-the-art climat e models being forced with increasing greenhouse gases (and other human-ca used pollution) are also simulating a steady decline in average wintertime precipitation in the Southwest. More troubling is the fact that these sim ulated changes are also in accord with what has been happening in the real world-- there is a growing scientific consensus that winters will become much hotter and significantly drier due to the greenhouse-gas climate forc ing. On top of these trends in average condition is the likelihood that mu lti-year\, even multi-decade\, drought will also become more common. Thus\ , the recent western drought--already the worst of the instrumental era--c ould be a harbinger of greater aridity to come\, and also a significant th reat to the West as we know it. Fortunately\, there are solutions if we ch oose to act aggressively.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080304T161500 DURATION:PT1H LOCATION:Keating 103 SUMMARY:Jonathan Overpeck: Climate Change\, Sea Level\, and Western Drought : Dangerous Anthropogenic Interference? UID:20080519T172633CEST-kRiDBG581V@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:Concentration inequalities provide effective tools in probabili stic contexts to deal with deviations of random variables from their expec tations. We will give an introduction to concentration inequalities in a c ontext that has applications\, or potential applications\, to questions in random matrix theory. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080304T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Nick Ercolani: Applications of Concentration Inequalities UID:20080519T172633CEST-ALIiJMTNFI@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Brown Bag DESCRIPTION:In this talk I will introduce the idea of a Riemann-Hilbert pro blem. In a nutshell\, this problem ask you to recover a complex function f rom its non-analytic behavior. We will derive a solution for a family of s imple RH problems\, and use some contour integral chicanery to solve a few examples. If time permits\, I will describe how such problems are related to the inverse scattering transform used to solve nonlinear integrable PD Es. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080229T120000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Bob Jenkins: Adventures in the Complex Plane UID:20080519T172633CEST-whf3IVzCZu@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:We present a novel computational methodology aimed at overcomin g the aforementioned difficulties. At the heart of our approach are integr al equation formulations that exhibit excellent spectral properties. In th e case of scattering from perfectly conducting structures\, and just as th e classical Combined Field Integral Equation (CFIE)\, our equations result from representations of the scattered fields as a combination of magnetic - and electric-dipole distributions on the surface of the scatterer. In co ntrast with the classical equations\, however\, our electric-dipole operat ors involve use of certain types of regularizing operators whose design is based on the pseudodifferential calculus on manifolds. We call the result ing equations Regularized Combined Field Integral Equations (CFIE-R). Unli ke the CFIE\, the CFIE-R are well-conditioned equations\; careful selectio n of coupling parameters\, further\, yields CFIE-R operators with excellen t spectral distributions--with closely clustered eigenvalues--so that smal l numbers of iterations suffice to solve the corresponding equations by me ans of Krylov subspace iterative solvers such as GMRES. We present a high- order Nystrom approach based on use of partitions of unity and high-order integration schemes that produces high-order algorithms for acoustic and e lectromagnetic scattering problems. A variety of numerical results demonst rate that\, for a given accuracy\, the new equations can give rise to orde r-of-magnitude reductions in computational costs over those resulting from previous approaches. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080228T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Catalin Turc: Fast\, high-order\, well-conditioned algorithms for t he solution of three-dimensional acoustic and electromagnetic scattering p roblems UID:20080519T172633CEST-2ukt47DbPE@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080227T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Kevin Lin: Some questions about coupled oscillator networks and rel ated systems UID:20080519T172633CEST-LlvNkn2RxS@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:Gradient flows ostensibly have dynamics that (1) result from th e decrease of energy and (2) do not exhibit oscillations. Neither of these statements is true for limits of singularly perturbed systems\, however. This talk illustrates these points in the context of liquid film evolution . \n\nEnergy-driven coarsening processes arise as the late-stage dynamics of many problems. Two examples are the spinodal decomposition of binary mi xtures and the dewetting of an unstable film of viscous liquid. The first case gives rise to Ostwald ripening\, where large particles grow at the ex pense of smaller ones by exchanging material. Migration of the particles a s a result of the ambient mass flux is a slower process and is usually ign ored. In contrast\, the nearly singular kinetics associated with the hydr odynamics of liquid films makes the role of migration significant. We disc uss this phenomenon from both a variational and a perturbation theory poin t of view. \n\nThe effects of gravity or hoop stress can also lead to migr ation\, but for different reasons. Interaction of droplets or fluid ridges is shown to give rise to a system which produces neighbor-neighbor repuls ion and oscillatory dynamics.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080226T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Karl Glasner: Migration Phenomena of Liquid Film Droplets and Surpr ises about Singularly Perturbed Gradient Flows UID:20080519T172633CEST-EHV2gFanVr@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:Molecular marker data is exceptional at determining whether a b iological sample (such as blood or an offspring!) came from a specified in dividual. Genealogists have become very interested in using molecular data to assess slightly more distant relationships\, those within 3-20 generat ions. I'll review why this is done using collections of completely linked markers (such as the Y chromosome) and discuss various statistical models for estimating the time to the most recent common ancestor given two such sequences. We start with a simple maximum likelihood approach\, discover i ts flaws\, and then develop a fully Bayesian estimator that addresses thes e concerns. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080226T041500 DURATION:PT1H LOCATION:Keating 103 SUMMARY:Bruce Walsh: Who's Your Great-great-great Granddaddy? Estimation o f Time to Most Recent Common Ancestor Given Molecular Genealogical Data UID:20080519T172633CEST-az1rCaVbUO@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:Cnidaria is an ancient phylum that includes solitary organisms like Hydra and sea anemones and colonial organisms like corals. Because of their apparent lack of bilaterality and their simple body plan\, Cnidaria ns were considered very unsophisticated organisms that should be easy to u nderstand. This view\, however\, has changed recently due to the discovery of numerous Cnidarian genes and signaling molecules that are also present in 'higher' organisms.\n\nFor a long time Hydra has been a model system f or developmental biology and a favorite pet for theorists. It is remarkabl e for its extraordinary regeneration capabilities that enable the survival of the organism from only 1% of the body tissue. In the course of regener ation Hydra forms a hollow sphere that undergoes cycles of oscillations. T he purpose of the oscillations has not yet been completely understood but is likely due to osmoregulation\, as I will argue in my talk.\n\nCorals gi ve rise to one of the world's most diverse ecosystems and fascinate becaus e of their bright colors and fantastic shapes. How these different shapes are created is still very much unclear. On the one hand\, genetic disposit ions must be important\; on the other hand\, environmental factors such as light and water flow modulate the growth significantly. In my talk I will summarize experimental work geared towards deciphering the rules of growt h in the coral Stylophora pistillata and present a model setup for studyin g these rules.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080222T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Michael Kuecken: Modeling Cnidarians: Oscillations in Hydra and Gro wth Rules in Corals UID:20080519T172633CEST-0NI9xGDFUK@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:I will present results from experiments on shaping of thin shee ts via lateral growth. Scaling of lengths scales and energies will be sugg ested and a possible geometrical origin of the appearance of small scale s tructure will be discussed. I will present first results from a study of g rowing leaves and will describe ongoing experiments. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080221T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Eran Sharon: Experiments in Non-Euclidean Plates and Leaves UID:20080519T172633CEST-XoaTGu9Dav@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080220T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Kevin Lin: Some questions about coupled oscillator networks and rel ated systems UID:20080519T172633CEST-h2jSeO7ki3@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:We have investigated the effect of DNA tension upon the associa tion and dissociation of the T7 RNA polymerase/promoter DNA interaction. U sing two optically trapped beads\, we suspended a single DNA molecule cont aining the T7-phi13 promoter above a 3rd surface-immobilized bead that bea rs active molecules of T7 RNAP. The DNA was brought into contact with the surface bead\, while applying a 50 Hz triangle oscillation to the bead ups tream of the promoter. Binding of T7 RNAP at the promoter was detected as the decoupling of motion of the two optically trapped beads: oscillations of the downstream bead are reduced or cease altogether upon binding. The D NA tension upon binding is directly proportional to the displacement of th e downstream bead from the center of the optical trap. By altering both th e mean tension in the DNA--changing trap stiffness or the mean bead-to-bea d distance--we have been able to observe promoter binding across the range of force 1-12 pN. From these data we find clear evidence that the mean li fetime of the promoter/T7 RNAP complex decreases with increasing tension a s indicated by an increasing dissociation rate constant\, koff\, from 3.5 s-1 at 1.5 pN up to 73 s-1 at >8 pN. From these observations\, we propose that tension within a DNA molecule is able to regulate gene expression\, a t least in the case of the bacteriophage T7 enzyme. Based on the recent st ructural data of the T7 RNAP initiation complex we speculate on the mechan ism by which force may affect the dissociation kinetics. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080219T161500 DURATION:PT1H LOCATION:Keating 103 SUMMARY:Gary Skinner: Mechanical Tension within DNA Controls Gene Transcrip tion Initiation UID:20080519T172633CEST-2T464LlupV@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:Compared to the plant and animal kingdoms\, diversity of microb ial life is considerably less explored and less understood (even the notio n of microbial species is a current topic of debate). Prokaryotes (bacteri a and archaea) are estimated to make up approximately half of extant bioma ss\; for example\, each human harbors about 100 trillion microbes (bacteri a and archaea)\, ten times more microbial than human cells. The familiar v iew of microbes in their free (planktonic) state is however not the norm\; rather it is believed that much of the microbial biomass\, perhaps 95-99% \, is located in close-knit communities\, designated biofilms and microbia l mats\, consisting of large numbers of organisms living within self-secre ted matrices constructed of polymers and other molecules. (Microbes in col lective behave very differently from their planktonic state\; even genetic expression patterns change.) These matrices serve the purposes of anchori ng and protecting their communities in favorable locations while providing a framework in which structured populations can differentiate and self-or ganize. \n\nOne can and will find biofilms in almost any damp or wet envir onment\, and they are often key players in problems such as human and anim al infections\, fouling of industrial equipment and water systems\, and wa ste remediation\, just to name a few. Medical relevance is quite dramatic. Quoting from the National Institutes of Health: 'Biofilms are clinically important\, accounting for over 80 percent of microbial infections in the body. Examples include: infections of the oral soft tissues\, teeth and de ntal implants\; middle ear\; gastro-intestinal tract\; urogenital tract\; airway/lung tissue\; eye\; urinary tract prostheses\; peritoneal membrane and peritoneal dialysis catheters\, in-dwelling catheters for hemodialysis and for chronic administration of chemotherapeutic agents (Hickman cathet ers)\; cardiac implants such as pacemakers\, prosthetic heart valves\, ven tricular assist devices\, and synthetic vascular grafts and stents\; prost heses\, internal fixation devices\, percutaneous sutures\; and tracheal an d ventilator tubing.'\n\nViewed as materials\, biofilms are quite interest ing: they are living\, growing viscoelastic fluids with surprising ability to respond to and defend against their environments. This talk will prese nt a general overview of efforts to characterize and model biofilms on a c ontinuum macroscale\, addressing some of the issues mentioned above. \n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080215T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Isaac Klapper: Microbial Biofilms UID:20080519T172633CEST-X9bluS1XU0@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080213T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Leo Lopes: Research Problems in Systems and Industrial Engineering UID:20080519T172633CEST-pLi1SKTnwG@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:Magnetic resonance imaging (MRI) is a common and useful tool in medicine and biology. Typically\, when MRI images are used by a radiologi st to make a clinical diagnosis\, the analysis of the images is carried ou t qualitatively and relies heavily on the experience of the radiologist. A lthough quantitative information is available in MRI\, it is typically not obtained because of the increased data acquisition time required and the ability of radiologists to make decisions without it. However\, in some ci rcumstances\, quantitative information can be very valuable in the diagnos is and evaluation of disease and in critical evaluation of therapy. A desc ription of quantitative parameters available from MRI experiments will be presented\, and research projects in which they are being used will be dis cussed. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080212T161500 DURATION:PT1H LOCATION:MRB 102 SUMMARY:Ted Trouard: Noninvasive Measurement of Tissue Properties with MRI UID:20080519T172633CEST-UIER2VVnzX@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:For the eigenvalues of a Schroedinger operator with a nonnegati ve potential\, Dolbeault\, Felmer\, Loss\, and Paturel proved (JFA\, 2006) a class of inequalities of Lieb-Thirring type relating functions of the s pectrum to (appropriate) integrals which depend on the potential. These in equalities include in particular the classical Golden-Thompson (also calle d Kac-Ray) inequality and a gamut of new inequalities for the spectral zet a function and other functions. \n\nIn this work\, we use the Bethe sum ru le and transform methods to prove a parallel set of inequalities for the e igenvalues of the fixed membrane problem. We also prove the equivalence of the Berezin-Li-Yau inequality with a classical inequality of Kac\, analyz e the work of A. Melas in a new light\, and propose new conjectures. \n\nT his is joint work with Professor Evans Harrell of Georgia Tech. \n\nA prep rint is available at http://arxiv.org/abs/0712.4088\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080212T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Lotfi Hermi: A Class of New Inequalities for the Eigenvalues of the Dirichlet Laplacian UID:20080519T172633CEST-z2GViWUokS@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:In the past several years it has come to be appreciated that in low Reynolds number flow the nonlinearities provided by non-Newtonian str esses of a complex fluid can provide a richness of dynamical behaviors mor e commonly associated with high Reynolds number Newtonian flow. For exampl e\, experiments have shown that dilute polymer suspensions being sheared i n simple flow geometries can exhibit highly time-dependent dynamics and sh ow efficient mixing. The corresponding experiments using Newtonian fluids do not show such nontrivial dynamics. To better understand these phenomena we study numerically the 2D Oldroyd-B Viscoelastic model at low Reynolds number. A background force is used to create a periodic cell with four-rol l mill vertical structure around a hyperbolic fixed point. We consider bot h steady and time-periodic forcing. For low Weissenberg number (Wi) the el astic stresses are bounded to the forcing\, with mixing confined to small sets near the hyperbolic point. At larger Wi an analog to the coil-stretch transition occurs\, yielding large stresses and stress gradients concentr ated on sets of small measure. The flow then becomes very sensitive to per turbations in the forcing and there is a transition to global mixing in th e fluid.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080208T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Becca Thomases: Singularities and Transport in Viscoelastic Fluids UID:20080519T172633CEST-1uzfO0ShUl@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080206T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Leo Lopes: Research Problems in Systems and Industrial Engineering UID:20080519T172633CEST-Fcl1KepIZH@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Quantitative Biology DESCRIPTION:In survival analysis\, censored observations can be regarded as missing event time data. We develop a direct approach\, multiple imputati on\, which shares common ideas with the redistribute to the right algorith m to recover information for censored observations. This approach can hand le both interval-censored and right-censored data. In one sample situation \, we show that with a large number of imputes the imputation method will reproduce the Kaplan-Meier estimates. In interval-censored data situations \, we propose a nonparametric multiple imputation scheme\, NPMLE imputatio n. The imputation methods convert interval-censored data problems to compl eted data problems\, which enables estimates of measures of uncertainty to be more easily obtained. In a situation with auxiliary variables\, we inc orporate auxiliary variables into imputation through two working Cox propo rtional hazards models and show that the imputation method can reduce bias due to dependent censoring and improve the efficiency. These findings of improved efficiency and reduced bias can be seen in both interval-censored and right-censored data. The methods are applied to AIDS data sets. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080205T161500 DURATION:PT1H LOCATION:Keating 103 SUMMARY:Chiu-Hsieh (Paul) Hsu: Survival Analysis via Multiple Imputation UID:20080519T172633CEST-dFfxUJxmf0@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:I will describe some open questions in the asymptotic analysis of Riemann-Hilbert problems\, random matrices\, and integrable PDEs. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080205T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Ken McLaughlin: A few open directions for research in random matric es\, integrable PDEs\, and Riemann-Hilbert problems UID:20080519T172633CEST-5RxDicdlGZ@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Special Events DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080205T090000 DURATION:PT1H LOCATION:MathEast 241 SUMMARY:Maxim Shkarayev: Effects of Nonlinearity and Disorder in Communicat ion Systems UID:20080519T172633CEST-Zzk7VcMjAV@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Brown Bag DESCRIPTION:Energy flows through a complex interacting network of living or ganisms\, from primary producers such as algae and plants\, to top predato rs such as sharks and parasites. Food webs are graphs representing these energy flows. These graphs can be viewed as couplings in a complex dynami cal system that describes changes in population sizes over time. Because of the interconnected nature of living organisms\, extinction of one speci es may have secondary effects that ripple throughout the ecosystem to vary ing degrees. In this talk\, I will give a basic introduction to food web s\, and discuss the basic network structures associated with them\, as wel l as the methods used to generate model food webs. I will also discuss fo od web dynamics\, and the effects of removing various types of organisms f rom an ecosystem network.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080201T120000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Rosalyn Rael: Who eats whom? Ecological structure and the effects of extinction on food webs UID:20080519T172633CEST-ZhBiTwpHui@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:By direct numerical simulation direct and inverse cascades in s urface gravity waves turbulence were observed. Formation of condensate in the low frequency waves region leads to the distortion of the exponents in Kolmogorov-like spectra predicted by the theory of weak turbulence. Also the influence of the wavenumbers grid discreteness was observed. The param eters of the simulation are typical for the laboratory water tanks experim ents. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080131T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Alexander O. Korotkevich: Simultaneous Observation of Direct and In verse Cascade in Surface Gravity Waves Turbulence UID:20080519T172633CEST-t4GHimWaPe@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080130T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Ardith El Kareh: Mathematical modeling of anticancer therapy UID:20080519T172633CEST-DVVAjmcH9x@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DESCRIPTION:Thin elastic sheets are very common in both natural and man-mad e structures. The configurations these structures assume in space are ofte n very complex and may contain many length scales\, even in the case of un constrained thin sheets. We will show evidence of the simplicity of the in trinsic geometry leading to these complex three-dimensional configurations \, and discuss the mechanism of shaping thin elastic sheets through the pr escription of intrinsic metric.\n\nCurrent reduced (two-dimensional) elast ic theories devised to describe thin structures treat either plates (flat bodies having no structure along their thin dimension) or shells (non-flat bodies having a non-trivial structure along their thin dimension). We pro pose the concept of non-Euclidean plates\, which are neither plates nor sh ells\, to approximate many naturally formed thin elastic structures. We de rive a thin plate theory which is a generalization of existing linear plat e theories for large displacements but small strains\, and arbitrary intri nsic geometry. We conclude by surveying some experimental results for labo ratory-engineered non-Euclidean plates. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080129T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Efi Efrati: Elastic Theory of Non-Euclidean Plates UID:20080519T172633CEST-UkdC68T7xw@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Special Events DESCRIPTION:Optically pumped semiconductor disk lasers (OPSDLs) combine the wavelength versatility and efficiency of diode lasers with the capability of a high output power emitted in a circular\, nearly diffraction-limited beam which is generally attributed to solid-state lasers. This favorable combination of properties has stimulated considerable current research and development activities in this class of lasers - mainly focused on GaInAs -based OPSDLs that emit at wavelengths around 1 um or in the visible spect ral range. However\, at wavelengths between 2 and 3 um there is also consi derable demand for compact and versatile high-brightness lasers\, e.g. for medical applications\, material processing or security applications.\n\nT he (AlGaIn)(AsSb) materials system is considered best suited to realise OP SDLs in this wavelength range\, and in this presentation\, an overview of recent development and achievements for 2.Xum OPSDLs will be given. Both b arrier pumped OPSDL (using 980 nm laser diodes as pump source) and in-well pumped OPSDL (using 1.96 um pump radiation) have been fabricated and char acterized. Using diamond or as an alternative SiC intracavity heatspreader \, multiple-watt CW-output powers have been achieved (e.g. >3W at 2.3 um a nd >5W at 2.0 um)\, with power efficiencies in the range of 18 % - 25 %. F or an optimised resonator setup\, the beam profile is close to the diffrac tion limit with M^2 values around 1.2\; and even for the highest power lev els\, M^2 is in the range of 2-5. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080128T140000 DURATION:PT1H LOCATION:Opti 8-th Floor Conference Room SUMMARY:Marcel Rattunde: High-performance optically pumped GaSb-based semic onductor disk lasers in the 2.Xum wavelength regime UID:20080519T172633CEST-mHVZ8KuJtv@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:The engineering community has been actively pursuing the develo pment of self-organization of particles in order to design smaller\, faste r and more efficient electronic elements. In order to achieve theoretical understanding of these processes\, we suggest a dissipative analogue of ki netic equations that describe the motion of probability distribution in th e momentum-coordinate space. This work is based on the double bracket diss ipation ideas that were originally suggested for astrophysical application s.\n\nWe then show how to extend the double bracket method to include part icles with interaction dependent on orientation\, for example\, magnetized particles in colloidal solution. We derive evolution equations for densit y and magnetization that reduce to the celebrated Landau-Lifshitz-Gilbert equations for non-moving magnets and to Debye-Huckel equations for particl es without orientation. We also show how our equations naturally give the motion for of an elastic self-interacting curve\, and discuss the applicat ion of our technique to folding of biologically-relevant strands.\n\nColla borators: Darryl D. Holm\, Cesare Tronci (Mathematics\, Imperial College\, London\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080125T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Vakhtang Putkaradze: Models of Dissipation and Self-Organization in Physical Systems: From Kinetic Equations to Self-Organization of Magnetic Particles to Protein UID:20080519T172633CEST-wLbT1W3jAi@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Special Events DESCRIPTION:Is the Brain like a computer? To what extent can we model the b rain with a set of mathematical equations? Can we model some specific brai n functions? Has the brain found an optimal solution to some computations? How does the brain represent space and time?\n\nIf you are intrigued by t hese questions and want to (actively) know more\, please join us for an in formal biweekly journal club on theoretical neuroscience every other Thurs day at 5 pm in the Mathematics building. We will go over some specific the mes such as 'decision making'\, 'learning with neurons'\, 'computing with oscillations'\, 'neurobiologically inspired computer vision'\, 'brain mach ine interfaces' and much more. Students who sign up are expected to presen t one or two papers relevant to the topic. Each paper is 'mentored' by one faculty. Some mathematical background is preferable. No neuroscience back ground is required.\n\nSponsored by the Program in Applied Mathematics\nJe an-Marc Fellous\, Michael Frank\, Chuck Higgins\, Tony Lewis and Kevin Lin \nPlease reply to Jean-Marc Fellous (fellous@email.arizona.edu)\, check th e website (http://emotion.nsma.arizona.edu/jclub.html) or just attend the first meeting Thursday Jan 24th \, 5pm\, in Math 402\, if you are interest ed. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080124T170000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Theoretical Neuroscience Journal Club UID:20080519T172633CEST-tomzUmchZw@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080124T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Organizational meeting UID:20080519T172633CEST-aoV3sdf6ff@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Math 586b DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080123T160000 DURATION:PT1H LOCATION:Math 101 SUMMARY:Ardith El-Kareh: Mathematical Modeling of Anticancer Therapy UID:20080519T172633CEST-J2dSVozgvb@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Analysis & Its Applications DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080122T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Organizational meeting UID:20080519T172633CEST-deldksg3jV@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Colloquium DESCRIPTION:Art Winfree's first scientific paper\, published in 1967 and ba sed on research he did as a senior in college\, was about synchronization of biological oscillators. In his honor\, this talk will survey what we kn ow (and don't know) about synchronization\, 40 years later.\n\nThe tendenc y to synchronize is one of the most mysterious and pervasive drives in all of nature. Every night along the tidal rivers of Malaysia\, thousands of fireflies flash in silent\, hypnotic unison\; the moon spins in perfect re sonance with its orbit around the Earth\; the intense coherence of a laser comes from trillions of atoms pulsing together. All these astonishing fea ts of synchrony occur spontaneously --- almost as if the universe had an o verwhelming desire for order.\n\nOn the surface\, these phenomena might se em unrelated. After all\, the forces that synchronize fireflies have nothi ng to do with those in a laser. But at a deeper level\, they are all conne cted by the same mathematical theme: self-organization\, the spontaneous e mergence of order out of chaos. Video footage of synchronous fireflies and the notorious crowd synchrony that triggered the wobbling of London's Mil lennium Bridge will be shown.\n DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080118T160000 DURATION:PT1H LOCATION:Math 501 SUMMARY:Steven Strogatz: Synchronization in Nature UID:20080519T172633CEST-D58CGRvVXL@appliedmath.arizona.edu END:VEVENT BEGIN:VEVENT CATEGORIES:Modeling & Computation DESCRIPTION:We analyze the interaction of an electromagnetic spike (one cyc le) with a thin layer of ferroelectric medium with two equilibrium states. The model is the set of Maxwell equations coupled to the undamped Landau- Khalatnikov equation\, where we do not assume slowly varying envelopes. Fr om linear scattering theory\, we show that low amplitude pulses can be com pletely reflected by the medium. Large amplitude pulses can switch the fer roelectric. Using numerical simulations and analysis\, we study this switc hing for long and short pulses\, estimate the switching times and provide useful information for experiments. DTSTAMP:20080519T152633Z DTSTART;TZID=US/Arizona:20080103T123000 DURATION:PT1H LOCATION:Math 402 SUMMARY:Jean-Guy Caputo: Electromagnetically induced switching of ferroelec tric thin films UID:20080519T172633CEST-CM70TKPgvU@appliedmath.arizona.edu END:VEVENT END:VCALENDAR