12,975 research outputs found

    Mid-IR period-magnitude relations for AGB stars

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    Asymptotic Giant Branch variables are found to obey period-luminosity relations in the mid-IR similar to those seen at K_S (2.14 microns), even at 24 microns where emission from circumstellar dust is expected to be dominant. Their loci in the M, logP diagrams are essentially the same for the LMC and for NGC6522 in spite of different ages and metallicities. There is no systematic trend of slope with wavelength. The offsets of the apparent magnitude vs. logP relations imply a difference between the two fields of 3.8 in distance modulus. The colours of the variables confirm that a principal period with log P > 1.75 is a necessary condition for detectable mass-loss. At the longest observed wavelength, 24 microns, many semi-regular variables have dust shells comparable in luminosity to those around Miras. There is a clear bifurcation in LMC colour-magnitude diagrams involving 24 micron magnitudes.Comment: 5 pages, 4 figure

    Controllability and observabiliy of an artificial advection-diffusion problem

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    In this paper we study the controllability of an artificial advection-diffusion system through the boundary. Suitable Carleman estimates give us the observability on the adjoint system in the one dimensional case. We also study some basic properties of our problem such as backward uniqueness and we get an intuitive result on the control cost for vanishing viscosity.Comment: 20 pages, accepted for publication in MCSS. DOI: 10.1007/s00498-012-0076-

    Obstacle avoidance for redundant robots using configuration control

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    A redundant robot control scheme is provided for avoiding obstacles in a workspace during the motion of an end effector along a preselected trajectory by stopping motion of the critical point on the robot closest to the obstacle when the distance between is reduced to a predetermined sphere of influence surrounding the obstacle. Algorithms are provided for conveniently determining the critical point and critical distance

    Aerothermal tests of spherical dome protuberances on a flat plate at a Mach number of 6.5

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    Aerothermal tests were conducted in the Langley 8-Foot High-Temperature Tunnel at a Mach number of 6.5 on a series of spherical dome protuberances mounted on a flat-plate test apparatus. Detailed surface pressure and heating-rate distributions were obtained for various dome heights and diameters submerged in both laminar and turbulent boundary layers including a baseline geometric condition representing a thermally bowed metallic thermal protection system (TPS) tile. The present results indicated that the surface pressures on the domes were increased on the windward surface and reduced on the leeward surface as predicted by linearized small-perturbation theory, and the distributions were only moderately affected by boundary-layer variations. Surface heating rates for turbulent flow increased on the windward surface and decreased on the leeward surface similar to the pressure; but for laminar boundary layers, the heating rates remained high on the leeward surface, probably due to local transition. Transitional flow effects cause heat load augmentation to increase by 30 percent for the maximum dome height in a laminar boundary layer. However, the corresponding augmentation for a dome with a height of 0.1 in. and a diameter of 14 in. representative of a bowed TPS tile was 14 percent or less for either a laminar or turbulent boundary layer

    Observations on the Interrelationships among Ants, Aphids, and Aphid Predators

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    Excerpt: The literature concerning the interactions of these insect groups is as interesting as it is extensive. It has generally been accepted that the relationship between ants and aphids has been one of mutualism in which ants derive all or a large part of their nutrients from aphid honeydew and perform special functions in return, primarily that of protecting aphids from their enemies. Every aspect of these associations has been covered by the excellent reviews of Nixon (1951) and Way (1963). It now appears that the nature and effectiveness of the protective value afforded the attended aphids by ants cannot be reduced to a simple statement of symbiosis. Nixon (1951) pointed out numerous situations that are responsible for fluctuations in the ant-aphid relationship. The emphasis in the present study was on the protection extended to Aphis rumicis Linn., a small aphid found on spirea shoots by the common tending ants. This restriction allowed constant surveillance of the protection supplied to a single aphid species by ants against the seasonal succession of predators. Aphid parasites were ignored in this study

    High-Stakes Testing and Student Achievement: Problems for the No Child Left Behind Act

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    Under the federal No Child Left Behind Act of 2001 (NCLB), standardized test scores are the indicator used to hold schools and school districts accountable for student achievement. Each state is responsible for constructing an accountability system, attaching consequences -- or stakes -- for student performance. The theory of action implied by this accountability program is that the pressure of high-stakes testing will increase student achievement. But this study finds that pressure created by high-stakes testing has had almost no important influence on student academic performance

    A simple model for DNA denaturation

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    Following Poland and Scheraga, we consider a simplified model for the denaturation transition of DNA. The two strands are modeled as interacting polymer chains. The attractive interactions, which mimic the pairing between the four bases, are reduced to a single short range binding term. Furthermore, base-pair misalignments are forbidden, implying that this binding term exists only for corresponding (same curvilinear abscissae) monomers of the two chains. We take into account the excluded volume repulsion between monomers of the two chains, but neglect intra-chain repulsion. We find that the excluded volume term generates an effective repulsive interaction between the chains, which decays as 1/rd‚ąí21/r^{d-2}. Due to this long-range repulsion between the chains, the denaturation transition is first order in any dimension, in agreement with previous studies.Comment: 10 page

    A Critical Review of "Automatic Patch Generation Learned from Human-Written Patches": Essay on the Problem Statement and the Evaluation of Automatic Software Repair

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    At ICSE'2013, there was the first session ever dedicated to automatic program repair. In this session, Kim et al. presented PAR, a novel template-based approach for fixing Java bugs. We strongly disagree with key points of this paper. Our critical review has two goals. First, we aim at explaining why we disagree with Kim and colleagues and why the reasons behind this disagreement are important for research on automatic software repair in general. Second, we aim at contributing to the field with a clarification of the essential ideas behind automatic software repair. In particular we discuss the main evaluation criteria of automatic software repair: understandability, correctness and completeness. We show that depending on how one sets up the repair scenario, the evaluation goals may be contradictory. Eventually, we discuss the nature of fix acceptability and its relation to the notion of software correctness.Comment: ICSE 2014, India (2014

    Features of pulsed synchronization of a systems with a tree-dimensional phase space

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    Features of synchronization picture in the system with the limit cycle embedded in a three-dimensional phase space are considered. By the example of Ressler system and Dmitriev - Kislov generator under the action of a periodic sequence of delta - function it is shown, that synchronization picture significantly depends on the direction of pulse action. Features of synchronization tons appeared in these models are observed.Comment: 16 pages, 11 figure

    Help-Seeking Pathways of African American Women Who Have Been Victims of Serious Non-Sexual Violent Crime

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    The University Archives has determined that this item is of continuing value to OSU's history.Session 3. Presenter: Lorri L. Glass, Ph.D. University of Illinois at Chicago (2007) - "Help-Seeking Pathways of African American Women Who Have Been Victims of Serious Non-Sexual Violent Crime"The Ohio State University College of Social Wor
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