26 research outputs found

    Evaluating Temporal Differences in Land Cover: Implications for Managing Bobwhite at the Landscape Scale in Virginia

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    Northern bobwhite (Colinus virginianus) populations have declined substantially across large portions of their range. A number of factors may be contributing to that decline including disease, predation, pesticides, and habitat loss. Of these, habitat loss has emerged as the primary factor. Habitat loss has occurred at large and small scales. It is relatively easy to evaluate bobwhite habitat at the micro scale, but evaluating habitat change at the landscape scale is difficult. The goal of this pilot study was to evaluate a novel technique using aerial imagery and line transects to evaluate both contemporary and historic landscapes effectively, quantifying the differences observed to describe what changes, if any, occurred through time. Contemporary photos were available through the 2013 Virginia Base Mapping Program. Historic photos were obtained via United States Geological Survey (1967 – 1969). Two Virginia Quail recovery Initiative focal counties were chosen for the study, Halifax (south central Piedmont) and Sussex (southeastern Coastal Plain). A 12-class habitat categorization system was developed to use in analysis. We developed a technique that allowed photo interpreters to identify and delineate features at a large scale (\u3e 1:6000) over a wide geographic area. Thirty-five to forty transects were evaluated for each site (n = 7). Favorable habitat decline observed ranged from -2% to -49%. Favorable edge decreased through time in four of five sites in Halifax County. Favorable edge increased dramatically within both Sussex County sites, particularly in the bobwhite focal area. Overall, habitat appears to have improved in Sussex County, and declined significantly in Halifax County. Habitats differed both through time and across the landscape. The largest habitat change noted was conversion from field to forest, predominantly pine. We feel this landscape scale habitat analysis technique holds much promise across the bobwhite’s range

    Aerodynamic Analyses and Database Development for Ares I Vehicle First Stage Separation

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    This paper presents the aerodynamic analysis and database development for first stage separation of Ares I A106 crew launch vehicle configuration. Separate 6-DOF databases were created for the first stage and upper stage and each database consists of three components: (a) isolated or freestream coefficients, (b) power-off proximity increments, and (c) power-on proximity increments. The isolated and power-off incremental databases were developed using data from 1% scaled model tests in AEDC VKF Tunnel A. The power-on proximity increments were developed using OVERFLOW CFD solutions. The database also includes incremental coefficients for one BDM and one USM failure scenarios

    A Pluralist Account of Knowledge as a Natural Kind

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    In an attempt to address some long-standing issues of epistemology, Hilary Kornblith proposes that knowledge is a natural kind the identification of which is the unique responsibility of one particular science: cognitive ethology. As Kornblith sees it, the natural kind thus picked out is knowledge as construed by reliabilism. Yet the claim that cognitive ethology has this special role has not convinced all critics. The present article argues that knowledge plays a causal and explanatory role within many of our more fruitful current theories, diverging from the reliabilist conception even in disciplines that are closely related to cognitive ethology, and thus still dealing with knowledge as a natural as opposed to a social phenomenon, where special attention will be given to cognitive neuroscience. However, rather than discarding the natural kind approach altogether, it is argued that many of Kornblith’s insights can in fact be preserved within a framework that is both naturalist and pluralist

    Review Section : Nature/Nurture Revisited I

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    Biologically oriented approaches to the study of human conflict have thus far been limited largely to the study of aggression. A sample of the literature on this topic is reviewed, drawing upon four major approaches: comparative psychology, ethology (including some popularized accounts), evolutionary-based theories, and several areas of human physiology. More sophisticated relationships between so-called "innate" and "acquired" determinants of behavior are discussed, along with the proper relevance of animal behavior studies for human behavior. Unless contained in a comprehensive theory which includes social and psychological variables, biolog ically oriented theories (although often valid within their domain) offer at best severely limited and at worst highly misleading explanations of complex social conflicts. The review concludes with a list of several positive contributions of these biological approaches and suggests that social scientists must become more knowledgeable about them.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68270/2/10.1177_002200277401800206.pd

    Coupled Simulation of CFD and Flight Mechanics with a Two-Species-Gas-Model for the Hot Staging of a Multistage Rocket

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    The hot staging dynamics of a multistage rocket is studied using the coupled simulation of Computational Fluid Dynamics (CFD) and Flight Mechanics (FM). In the coupled simulations, the free-stream is modeled as “cold air” and the exhausted plume from the continuing-stage-motor is modeled with an equivalent calorically-perfect-gas that approximates the properties of the plume at the nozzle exit. The Navier-Stokes equations in the coupled simulations are time-accurately solved in moving system, with which the Flight Mechanics equations can be fully coupled. The Chimera mesh technique is utilized to deal with the relative motions of the separated stages. A few representative staging cases with different initial flight conditions of the rocket are studied with the coupled simulation. Based on the simulation results, the staging dynamics of the rocket are finally analyzed

    Development and Validation of an Instrument for Assessing Distance Education Learning Environments in Higher Education: The Distance Education Learning Environments Survey (DELES)

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    The purpose of this study was to develop and validate a new learning environments instrument designed to aid investigators and practitioners in measuring and researching the psychosocial learning environment in post-secondary distance education. Using a three-stage approach, the Distance Education Learning Environments Survey (DELES) was developed, field-tested with 680 distance education students, and then validated. The DELES has 34 items allocated to six scales: (1) Instructor Support; (2) Student Interaction and Collaboration; (3) Personal Relevance; (4) Authentic Learning; (5) Active Learning; and (6) Student Autonomy. An additional scale of Enjoyment was included in this study to explore associations between the psychosocial learning environment and student affective traits. Each learning environment item had a factor loading of at least 0.50 with its own scale, and less than 0.50 with all other scales. The alpha reliability coefficient for each scale ranged from 0.75 to 0.94. Simple correlations between Enjoyment and the DELES scales ranged from 0.12 to 0.31, with the scale of Personal Relevance having the strongest correlation with Enjoyment when all other scales were mutually controlled. The DELES, an online instrument that can be utilized by students at any location, eliminates data transfer errors and does not allow for non-responses, adding to the overall validity of the instrument. The development of DELES relied extensively on literature pertaining to high-quality distance education and expert content validation techniques. It treats distance learning as having a distinct social-psychological climate unlike those found in other post-secondary classroom environments
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