5,342 research outputs found

    A Massive Data Parallel Computational Framework for Petascale/Exascale Hybrid Computer Systems

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    Heterogeneous systems are becoming more common on High Performance Computing (HPC) systems. Even using tools like CUDA and OpenCL it is a non-trivial task to obtain optimal performance on the GPU. Approaches to simplifying this task include Merge (a library based framework for heterogeneous multi-core systems), Zippy (a framework for parallel execution of codes on multiple GPUs), BSGP (a new programming language for general purpose computation on the GPU) and CUDA-lite (an enhancement to CUDA that transforms code based on annotations). In addition, efforts are underway to improve compiler tools for automatic parallelization and optimization of affine loop nests for GPUs and for automatic translation of OpenMP parallelized codes to CUDA. In this paper we present an alternative approach: a new computational framework for the development of massively data parallel scientific codes applications suitable for use on such petascale/exascale hybrid systems built upon the highly scalable Cactus framework. As the first non-trivial demonstration of its usefulness, we successfully developed a new 3D CFD code that achieves improved performance.Comment: Parallel Computing 2011 (ParCo2011), 30 August -- 2 September 2011, Ghent, Belgiu

    Status of the profession

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    The number of astronomers has grown by about 40 percent over the past decade. The number of astronomers with jobs in industry, or with long-term, non-tenured, jobs has increased dramatically compared with traditional faculty positions. The increase in the number of astronomers and the declining share of the NSF budget going to astronomy has led to extreme difficulties in the NSF grant program and in support of the National Observatories. In 1989, direct NASA support of astronomers through the grants program exceeds that of NSF, although the total of the NSF grants program over decade far exceeds that of NASA. Access to major new telescopes will be important issue for the 1990s. US astronomers, who once had a monopoly on telescopes larger than 3 meters, will, by the year 2000, have access to just half of the world's optical telescope area

    University of Windsor Graduate Calendar 2004 Fall Electronic Edition

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    https://scholar.uwindsor.ca/universitywindsorgraduatecalendars/1028/thumbnail.jp

    A Universal Scheme for Wyner–Ziv Coding of Discrete Sources

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    We consider the Wyner–Ziv (WZ) problem of lossy compression where the decompressor observes a noisy version of the source, whose statistics are unknown. A new family of WZ coding algorithms is proposed and their universal optimality is proven. Compression consists of sliding-window processing followed by Lempel–Ziv (LZ) compression, while the decompressor is based on a modification of the discrete universal denoiser (DUDE) algorithm to take advantage of side information. The new algorithms not only universally attain the fundamental limits, but also suggest a paradigm for practical WZ coding. The effectiveness of our approach is illustrated with experiments on binary images, and English text using a low complexity algorithm motivated by our class of universally optimal WZ codes

    The William Kruskal Legacy: 1919--2005

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    William Kruskal (Bill) was a distinguished statistician who spent virtually his entire professional career at the University of Chicago, and who had a lasting impact on the Institute of Mathematical Statistics and on the field of statistics more broadly, as well as on many who came in contact with him. Bill passed away last April following an extended illness, and on May 19, 2005, the University of Chicago held a memorial service at which several of Bill's colleagues and collaborators spoke along with members of his family and other friends. This biography and the accompanying commentaries derive in part from brief presentations on that occasion, along with recollections and input from several others. Bill was known personally to most of an older generation of statisticians as an editor and as an intellectual and professional leader. In 1994, Statistical Science published an interview by Sandy Zabell (Vol. 9, 285--303) in which Bill looked back on selected events in his professional life. One of the purposes of the present biography and accompanying commentaries is to reintroduce him to old friends and to introduce him for the first time to new generations of statisticians who never had an opportunity to interact with him and to fall under his influence.Comment: This paper discussed in: [arXiv:0710.5072], [arXiv:0710.5074], [arXiv:0710.5077], [arXiv:0710.5079], [arXiv:0710.5081], [arXiv:0710.5084] and [arXiv:0710.5085]. Published in at http://dx.doi.org/10.1214/088342306000000420 the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

    A Proposal to Improve Our Understanding of Entrepreneurship Using the Panel Study of Income Dynamics

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    This paper aims to evidence how relatively marginal changes in the Panel Study of Income Dynamics survey, particularly on the measurement of returns to entrepreneurship - both financial and human capital - can yield sizeable benefits for research and policy on entrepreneurship. Accurate measurement of returns to all the resources invested in entrepreneurial endeavors is not only essential to understand the motivations and barriers to start a business, but can ultimately provide the basis to improve the effectiveness of programs and policies to foster entrepreneurial activity in the economy.In fact, recent studies question the importance of pecuniary benefits in the decision to become an entrepreneur. However, these are based on measures of total earnings and sample aggregate returns. Thus, adequate individual data on business income and its components has an enormous value for both research and policy design altogether.entrepreneurship, returns to entrepreneurship, survey, PSID

    The Impact of Research Grant Funding on Scientific Productivity

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    In this paper, we estimate the impact of receiving an NIH grant on subsequent publications and citations. Our sample consists of all applications (unsuccessful as well as successful) to the NIH from 1980 to 2000 for postdoctoral training grants (F32s) and standard research grants (R01s). Both OLS and regression discontinuity estimates show that receipt of either an NIH postdoctoral fellowship or research grant leads to about one additional publication over the next five years. The estimates represent about 20 and 7 percent increases in research productivity for F32 and R01 recipients respectively. The limited research impact of NIH grants may be explained in part by a model in which the market for research funding is competitive, so that the loss of an NIH grant simply causes researchers to shift to another source of funding.

    SN~2012cg: Evidence for Interaction Between a Normal Type Ia Supernova and a Non-Degenerate Binary Companion

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    We report evidence for excess blue light from the Type Ia supernova SN 2012cg at fifteen and sixteen days before maximum B-band brightness. The emission is consistent with predictions for the impact of the supernova on a non-degenerate binary companion. This is the first evidence for emission from a companion to a SN Ia. Sixteen days before maximum light, the B-V color of SN 2012cg is 0.2 mag bluer than for other normal SN~Ia. At later times, this supernova has a typical SN Ia light curve, with extinction-corrected M_B = -19.62 +/- 0.02 mag and Delta m_{15}(B) = 0.86 +/- 0.02. Our data set is extensive, with photometry in 7 filters from 5 independent sources. Early spectra also show the effects of blue light, and high-velocity features are observed at early times. Near maximum, the spectra are normal with a silicon velocity v_{Si} = -10,500$ km s^{-1}. Comparing the early data with models by Kasen (2010) favors a main-sequence companion of about 6 solar masses. It is possible that many other SN Ia have main-sequence companions that have eluded detection because the emission from the impact is fleeting and faint.Comment: accepted to Ap

    Where do Innovations Come From? Transformations in the U.S. Economy, 1970-2006

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    This article brings to bear new data on the issue of structuring national innovation systems. Drawing on a unique data set of prize winning innovations between 1971 and 2006, we document three key changes in the U.S. economy. The first is an expanding role of interorganizational collaborations in producing award winning innovations. The second is the diminishing role of the largest corporations as sources of innovation. The third is the expanded role of public institutions and public funding in the innovation process. This leads us to the surprising conclusion that the U.S. increasingly resembles a Developmental Network State in which government initiatives are critical in overcoming network failures and in providing critical funding for the innovation process. The paper concludes by addressing the implications of these finding for debates over the appropriate regime for intellectual property rights.
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