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2006 MRS Fall Meeting

作者： Hazair, S. Van Der Wilt, P.C. Deng, Y. Chung, U.-J. Limanov, A.B. Im, James S. Program of Materials Science Department of Applied Physics and Applied Mathematics Columbia University New York NY 10027 United States

ISBN: (纸本)9781604234282

Thin Si films on SiO2 that are completely melted by pulsed laser irradiation cool rapidly and eventually solidify via nucleation and growth of solids. It has been observed that a variety of solidified microstructures can be obtained, depending primarily (but not exclusively) on the degree of supercooling achieved prior to the onset of nucleation. This paper focuses on investigating one particular and unusual polycrystalline microstructure that consists of "flower-like" grains, the interiors of which can be described as being made up of two distinct regions: (1) an extremely defective core region consisting of fine-grained material, and (2) an outer region consisting of relatively defect-free crystal "petals" that radiate outwards. After considering the microstructural details and experimental behavior of the microstructure, we have formulated a growth-based physical model to account for the formation of the microstructure. The model is found to be also capable of accounting for other complex and unusual microstructures obtained via nucleation and growth in the complete melting regime. © 2007 Materials Research Society.

关键词： Thin films

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Platelet Gene/Protein Expression Analyses Using an Integrated Platform.

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Blood 2007年第11期110卷 3645-3645页

作者： Dmitri V. Gnatenko Peter L. Perrotta Chen Ji Wei Zhu Wadie F. Bahou Department of Medicine State University of New York Stony Brook NY USA Department of Pathology West Virginia University Morgantown WV USA Department of Applied Mathematics and Statistics SUNY Stony Brook NY USA Program in Genetics SUNY Stony Brook NY USA

Molecular profiling strategies generally apply either transcriptomic or proteomic technologies for dissection of aberrant expression patterns between normal and diseased samples. Although studies in yeast ( S. cerevisiae ) demonstrate excellent concordance between gene/protein abundance, the lack of integrated comparisons using human systems prompted us to stringently dissect these relationships in a cellular model system (platelets) devoid of active transcriptional activity. Highly-purified platelets from four healthy donors were pooled for proteomic analyses which were completed in duplicate using tryptic digestion of 100 mg cytoplasmic fractions, followed by cation exchange liquid chromatography coupled to tandem mass spectrometry (μLC-MS/MS). Spectral (peptide) counts were used as a semi-quantitative means of establishing protein abundance among normalized MS data sets, with excellent concordance between platelet runs (Spearman rank correlation r = 0.87, p <0.0001). Microarray data derived from five platelet apheresis donors were hybridized to the Affymetrix HU133a gene chip, and relative transcript abundance established by rank-ordering the unique, normalized set of non-redundant mRNAs (N=1240). Two comprehensive bioinformatics approaches using either platelet-restricted or genome-wide relational databases were additive in identifying 690 unique platelet proteins, representing increase of 230% or 131% to either approach alone. Of the identified proteins, 72% had a corresponding mRNA transcript, although a smaller fraction of mRNAs (41%) had a corresponding protein. The calculated codon adaptation index (CAI) for the 156 highest- and the 156 lowest-expressed platelet transcripts predicted strong correlation to protein abundance. Spearman correlations on data rank-ordered by either protein or transcript abundance demonstrated a maximal correlation coefficient of 0.44 (p =0.034) for an 18-member protein subset (higher protein abundance), although the 20 most abund

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Learning representation and control in continuous Markov decision processes

Learning representation and control in continuous Markov dec...

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21st National Conference on Artificial Intelligence and the 18th Innovative Applications of Artificial Intelligence Conference, AAAI-06/IAAI-06

作者： Mahadevan, Sridhar Maggioni, Mauro Ferguson, Kimberly Osentoski, Sarah Department of Computer Science University of Massachusetts 140 Governor's Drive Amherst MA 01003 Program in Applied Mathematics Department of Mathematics Yale University New Haven CT 06510

ISBN: (纸本)1577352815

This paper presents a novel framework for simultaneously learning representation and control in continuous Markov decision processes. Our approach builds on the framework of proto-value functions, in which the underlying representation or basis functions are automatically derived from a spectral analysis of the state space manifold. The proto-value functions correspond to the eigenfunctions of the graph Laplacian. We describe an approach to extend the eigenfunctions to novel states using the Nyström extension. A least-squares policy iteration method is used to learn the control policy, where the underlying subspace for approximating the value function is spanned by the learned proto-value functions. A detailed set of experiments is presented using classic benchmark tasks, including the inverted pendulum and the mountain car, showing the sensitivity in performance to various parameters, and including comparisons with a parametric radial basis function method. Copyright © 2006, American Association for Artificial Intelligence (***). All rights reserved.

关键词： Knowledge representation

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A class of nonsymmetric preconditioners for saddle point problems

A class of nonsymmetric preconditioners for saddle point pro...

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作者： Botchev, Mike A. Golub, Gene H. Department of Applied Mathematics University of Twente P.O. Box 217 7500 AE Enschede Netherlands Scientific Computing and Computational Mathematics Program Stanford University Stanford CA 94305-9025

For the iterative solution of saddle point problems, a nonsymmetric preconditioner is studied which, with respect to the upper-left block of the system matrix, can be seen as a variant of SSOR. An idealized situation where SSOR is taken with respect to the skew-symmetric part plus the diagonal part of the upper-left block is analyzed in detail. Since action of the preconditioner involves solution of a Schur complement system, an inexact form of the preconditioner can be of interest. This results in an inner-outer iterative process. Numerical experiments with solution of linearized Navier-Stokes equations demonstrate the efficiency of the new preconditioner, especially when the upper-left block is far from symmetric. © 2006 Society for Industrial and applied mathematics.

关键词： Problem solving

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Criteria for rapid mixing of gibbs samplers and uniqueness of gibbs measures 44

Criteria for rapid mixing of gibbs samplers and uniqueness o...

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44th Annual Allerton Conference on Communication, Control, and Computing 2006

作者： Winkler, Stephan Tatikonda, Sekhar Program in Applied Mathematics Yale University CT06520 United States Department of Electrical Engineering Yale University CT06520 United States

ISBN: (纸本)9781604237924

We survey conditions for rapid mixing of certain Markov chains, called Gibbs samplers, and uniqueness of certain probability measures with prescribed finite dimensional conditional distributions, called Gibbs measures. By Tatikonda and Jordan's [1] sufficiency result, these criteria translate into conditions for convergence of the Sum-Product algorithm. The basic idea, which goes back to Dobrushin [2], is to show that the transition kernels (in the Gibbs sampler case) or the prescribed conditional distributions (in the Gibbs measure case) act as contractions on spaces of functions or measures, provided they are weakly influenced by neighboring sites. The contributions of this paper are as follows: We compare various notions of influence, unifying notation and terminology currently scattered across a large body of literature. We survey, generalize and extend existing proof techniques which fall in three broad categories: analytic arguments, coupling arguments, and arguments using path coupling. In particular, we extend all arguments from single sites to finite blocks and from total variation to Wasserstein distance;we introduce new matrix methods;we answer an open question by Weitz [3];and we provide evidence to support the superiority of path coupling, addressing a question raised by Sokal [4] regarding the dual relationship of analytic and coupling techniques.

关键词： Surveys

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Second-order Sigma-Delta (ΣΔ) quantization of finite frame expansions

Second-order Sigma-Delta (ΣΔ) quantization of finite frame...

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作者： Benedetto, John J. Powell, Alexander M. Yilmaz, Özgür Department of Mathematics University of Maryland College Park MD 20742 United States Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 United States Department of Mathematics University of British Columbia Vancouver BC V6T 1Z2 Canada

The second-order Sigma-Delta (ΣΔ) scheme with linear quantization rule is analyzed for quantizing finite unit-norm tight frame expansions for Rd. Approximation error estimates are derived, and it is shown that for certain choices of frames the quantization error is of order 1/N2, where N is the frame size. However, in contrast to the setting of bandlimited functions there are many situations where the second-order scheme only gives approximation error of order 1/N. For example, this is the case when quantizing harmonic frames of odd length in even dimensions. An important component of the error analysis involves extending existing stability results to yield smaller invariant sets for the linear second-order ΣΔ scheme. © 2005 Elsevier Inc. All rights reserved.

关键词： Estimation

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Numerical and asymptotical study of three-dimensional wave packets in a compressible boundary layer

Numerical and asymptotical study of three-dimensional wave p...

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36th AIAA Fluid Dynamics Confernce

作者： Forgoston, Eric Viergutz, Michael Tumin, Anatoli University of Arizona Tucson AZ 85721 United States Program in Applied Mathematics United States AIAA United States Mechanical Engineering Department of Aerospace and Mechanical Engineering

ISBN: (纸本)1563478102

A three-dimensional wave packet generated by a local disturbance in a two-dimensional hypersonic boundary layer flow is studied with the aid of the previously solved initialvalue problem. The solution can be presented as a sum of modes consisting of continuous and discrete spectra of temporal stability theory. Two discrete modes, known as Mode S and Mode F, are of interest in high-speed flows since they may be involved in a laminar-turbulent transition scenario. The continuous and discrete spectra are analyzed numerically for a hypersonic flow. A comprehensive study of the spectrum is performed, including Reynolds number, Mach number and temperature factor effects. A specific disturbance consisting of an initial temperature spot is considered, and the receptivity to this initial temperature spot is computed for both the two-dimensional and three-dimensional cases. Using the analysis of the discrete and continuous spectrum, the inverse Fourier transform is computed numerically. The two-dimensional inverse Fourier transform is calculated for Mode F and Mode S. The Mode S result is compared with an asymptotic approximation of the Fourier integral, which is obtained using a Gaussian model as well as the method of steepest descent. Additionally, the three-dimensional inverse Fourier transform is found using an asymptotic approximation. Using the inverse Fourier transform computations, the development of the wave packet is studied, including effects due to Reynolds number, Mach number and temperature factor.

关键词： Boundary layer flow

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A multiobjective optimization approach to smart growth in land development

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Socio-Economic Planning Sciences 2006年第3期40卷 212-248页

作者： Gabriel, Steven A. Faria, José A. Moglen, Glenn E. Department of Civil and Environmental Engineering University of Maryland College Park MD 20742 United States Applied Mathematics and Scientific Computation Program University of Maryland College Park MD 20742 United States

In this paper we apply a multiobjective optimization model of Smart Growth to land development. The term Smart Growth is meant to describe development strategies-that do not promote urban sprawl. However, the term is somewhat open to interpretation. The multiobjective aspects arise when considering the conflicting interests of the various stakeholders involved in land development decisions: the government planner, the environmentalist, the conservationist, and the land developer. We present a formulation-employing linear and convex quadratic objective functions subject to polyhedral and binary constraints for the stakeholders. The resulting optimization problems are convex, quadratic mixed integer programs that are NP-complete. We report numerical results with this model for Montgomery County, Maryland, and present them using a geographic information system (GIS). © 2005 Elsevier Ltd. All rights reserved.

关键词： Geographic Information System Integer programming Land use planning Large Scale Optimization Multiple objective programming Quadratic programming Smart Growth

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SLS of Si films on polymer substrates: Materials and devices

SLS of Si films on polymer substrates: Materials and devices

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IMID/IDMC 2006: 6th Internaional Meeting on Information Display and the 5th International Display Manufacturing Conference

作者： Limanov, A.B. Van Der Wilt, P.C. Kane, M.G. Firester, A.M. Goodman, L. Lee, J. Abelson, J.R. Im, James S. Program in Materials Science and Engineering Department of Applied Physics and Applied Mathematics Columbia University New York NY United States Sarnoff Corporation Princeton NJ United States Department of Materials Science and Engineering University of Illinois Urbana IL United States

A number of research groups and companies have succeeded in employing various SLS schemes to create low defect-density Si films on glass substrates for making high performance TFTs, In this paper, we first point out that SLS can be utilized to just as effectively handle crystallization of thin Si films on polymer substrates, and then present preliminary results on high-performance circuits that are built using the materials.

关键词： Thin films

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Delay Performance under the Joint Scheduling over Gilbert-Elliot Channel

Delay Performance under the Joint Scheduling over Gilbert-El...

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Wireless Telecommunications Symposium, WTS

作者： Fumio Ishizaki Gang Uk Hwang Department of Mathematics and Telecommunication Mathematics Korea University South Korea Division of Applied Mathematics and Telecommunication Engineering Program Korea Advanced Institute of Science and Technology

In this paper, we consider a joint scheduling algorithm which is a combination of Knopp and Humblet (KH) scheduling, which fully exploits multiuser diversity, and round-robin (RR) scheduling, which does not use multiuser diversity at all. By assuming that the wireless channel process for each user is described by Gilbert-Elliot channel model, we develop a formula to estimate the tail distribution of packet delay for an arbitrary user under the joint scheduling. Numerical results exhibit that under the joint scheduling; the ratio of the number of slots assigned for the RR scheduling to that for the KH scheduling dominates the delay performance

关键词： Delay estimation Scheduling algorithm Probability distribution Wireless networks Telecommunication traffic mathematics Fading Throughput Predictive models Performance analysis

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