5,256 research outputs found

    Hearing the shape of a room

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    PMCID: PMC3725052The final published version of this article can be found here: www.pnas.org/cgi/doi/10.1073/pnas.130993211

    Cosmic-Ray Rejection by Laplacian Edge Detection

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    Conventional algorithms for rejecting cosmic-rays in single CCD exposures rely on the contrast between cosmic-rays and their surroundings, and may produce erroneous results if the Point Spread Function (PSF) is smaller than the largest cosmic-rays. This paper describes a robust algorithm for cosmic-ray rejection, based on a variation of Laplacian edge detection. The algorithm identifies cosmic-rays of arbitrary shapes and sizes by the sharpness of their edges, and reliably discriminates between poorly sampled point sources and cosmic-rays. Examples of its performance are given for spectroscopic and imaging data, including HST WFPC2 images.Comment: Accepted for publication in the PASP (November 2001 issue). The algorithm is implemented in the program L.A.Cosmic, which can be obtained from http://www.astro.caltech.edu/~pgd/lacosmic

    Towards a contextual approach to the place–homeless survival nexus: An exploratory case study of Los Angeles County

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    The characteristics of the immediate locale greatly affect the ability of homeless people to adapt to life on the street and in shelters, with different types of places nurturing different circumstances for survival. Current conceptualizations of the place–survival nexus are too narrow, relying on small-scale, intensive studies of particular places that are known to sustain homeless survival while ignoring more suburban and exurban locales, as well as failing to set these places of survival within the larger socio-economic spaces of the metropolitan area. Further, the literature is heavily qualitative, lacking any kind of ‘‘big picture” quantitative assessment of the nexus. In response, we contribute to the place–survival nexus literature by developing a typology of space for homeless survival and then use interview data to examine the variation in survival strategies across three types of urban space in Los Angeles County. Our results speak to how our innovative and exploratory approach enabled a broader, more extensive and variegated understanding of place–survival among homeless people than previous studie


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    AbstractMaster is a powerful search/data management software specifically designed to help quickly locate relevant medical articles indexed by the National Library of Medicine* (NLM), to help keep track searches, what one has read, catalog references and full text articles, to assist in the review and analysis of articles for referencing, publishing and research purposes. Basically, an electronic finder/cataloguer/ organizer for the sciences of medicine

    Inheritance of Resistance to Six Races of Bunt, to Awns and Kernel Color in a Wheat Cross

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    Wheat is the most important cereal crop of the world, and one of the most serious diseases affecting it over much of its range is covered smut or bunt (57). The word bunt , according to Heald (48), is a contraction of an old English term, burnt ear , which fittingly describes the ravages of covered smut

    Neighborhoods of Refuge: Faculty -Student-Community Research on Homelessness Proposal

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    Matthew D. Marr\u27s proposal shares his effective community research project with FIU, Miami-Dade College, and Camillus House. Through GIS mapping and qualitative research (PhotoVoice and interviews), the project highlights the role of neighborhoods in addressing homelessness

    Neighborhoods of Refuge: Faculty -Student-Community Research on Homelessness Slides

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    Matthew D. Marr\u27s slides for his project Neighborhoods of Refuge: Faculty -Student-Community Research on Homelessnes

    Hidden Cues in Random Line Stereograms

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    Successful fusion of random-line stereograms with breaks in the vernier acuity range has been interpreted to suggest that the interpolation process underlying hyperacuity is parallel and preliminary to stereomatching. In this paper (a) we demonstrate with computer experiments that vernier cues are not needed to solve the stereomatching problem posed by these stereograms and (b) we provide psychophysical evidence that human stereopsis probably does not use vernier cues alone to achieve fusion of these random-line stereograms.MIT Artificial Intelligence Laborator

    Analysis of the wind tunnel test of a tilt rotor power force model

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    Two series of wind tunnel tests were made to determine performance, stability and control, and rotor wake interaction on the airframe, using a one-tenth scale powered force model of a tilt rotor aircraft. Testing covered hover (IGE/OCE), helicopter, conversion, and airplane flight configurations. Forces and moments were recorded for the model from predetermined trim attitudes. Control positions were adjusted to trim flight (one-g lift, pitching moment and drag zero) within the uncorrected test data balance accuracy. Pitch and yaw sweeps were made about the trim attitudes with the control held at the trimmed settings to determine the static stability characteristics. Tail on, tail off, rotors on, and rotors off configurations were testes to determine the rotor wake effects on the empennage. Results are presented and discussed

    Black-fly and the Environment

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