544 research outputs found

    The Effect of Teachers' Memory‐Relevant Language on Children's Strategy Use and Knowledge

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/101866/1/cdev12100.pd

    Surface characterization of selected LDEF tray clamps

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    The surface characterization of chromic acid anodized 6061-T6 aluminum alloy tray clamps has shown differences in surface chemistry depending upon the position on the Long Duration Exposure Facility (LDEF). Water contact angle results showed no changes in wettability of the tray clamps. The overall surface topography of the control, trailing edge(E3) and leading edge(D9) samples was similar. The thickness of the aluminum oxide layer for all samples determined by Auger depth profiling was less than one micron. X-ray photoelectron spectroscopy (XPS) analysis of the tray clamps showed significant differences in the surface composition. Carbon and silicon containing compounds were the primary contaminants detected

    The Lasting Effects of Growing up in a Military-Connected Home: A Qualitative Study of College-Aged American Military Kids

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    Being reared as a military kid is a unique experience shared by millions of children all over the world. This study seeks to understand the experiences shared by military kids and how those experiences change their perspectives, behaviours, and relationships. In the present phenomenological study, we conducted 21 in-depth, semi-structured qualitative interviews of college students who were reared as United States military kids (MKs). Using criterion sampling, the participants all met specific criteria, including experiencing deployment of their military parent as well as a minimum of 10 years of parental service during the MK’s lifetime. Interviews were tape-recorded, transcribed, and coded for analysis. Researchers reviewed the transcriptions to find common themes and meta-themes present in a majority of the interviews. Common themes centred around relationships with family, changes during childhood, and military presence in everyday life. Particular findings reported in the present article include demonstrated respect, military pride, military community commonality, anticipation of change, childhood instability, family dynamics, military terminology, adaptability, and an overall positive experience. These common themes are relevant for all involved in the care of military kids and their families, as they underline the unique perspective that MKs have about their childhood and their future

    Surface characterization of LDEF carbon fiber/polymer matrix composites

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    XPS (x-ray photoelectron spectroscopy) and SEM (scanning electron microscopy) analysis of both carbon fiber/epoxy matrix and carbon fiber/polysulfone matrix composites revealed significant changes in the surface composition as a result of exposure to low-earth orbit. The carbon 1s curve fit XPS analysis in conjunction with the SEM photomicrographs revealed significant erosion of the polymer matrix resins by atomic oxygen to expose the carbon fibers of the composite samples. This erosion effect on the composites was seen after 10 months in orbit and was even more obvious after 69 months

    Next-to-leading order QCD calculations with parton showers II: soft singularities

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    Programs that calculate observables in quantum chromodynamics at next-to-leading order typically generate events that consist of partons rather than hadrons -- and just a few partons at that. These programs would be much more useful if the few partons were turned into parton showers, which could be given to one of the Monte Carlo event generators to produce hadron showers. In a previous paper, we have seen how to generate parton showers related to the final state collinear singularities of the perturbative calculation for the example of e+ + e- --> 3 jets. This paper discusses the treatment of the soft singularities.Comment: 26 pages with 5 figures. This version is close to the version to be publishe

    The KLN Theorem and Soft Radiation in Gauge Theories: Abelian Case

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    We present a covariant formulation of the Kinoshita, Lee, Nauenberg (KLN) theorem for processes involving the radiation of soft particles. The role of the disconnected diagrams is explored and a rearrangement of the perturbation theory is performed such that the purely disconnected diagrams are factored out. The remaining effect of the disconnected diagrams results in a simple modification of the usual Feynman rules for the S-matrix elements. As an application, we show that when combined with the Low theorem, this leads to a proof of the absense of the 1/Q1/Q corrections to inclusive processes (like the Drell-Yan process). In this paper the abelian case is discussed to all orders in the coupling.Comment: 27 pages, LaTeX, 14 figure

    New measurement of the scattering cross section of slow neutrons on liquid parahydrogen from neutron transmission

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    Liquid hydrogen is a dense Bose fluid whose equilibrium properties are both calculable from first principles using various theoretical approaches and of interest for the understanding of a wide range of questions in many body physics. Unfortunately, the pair correlation function g(r)g(r) inferred from neutron scattering measurements of the differential cross section dσdΩd\sigma \over d\Omega from different measurements reported in the literature are inconsistent. We have measured the energy dependence of the total cross section and the scattering cross section for slow neutrons with energies between 0.43~meV and 16.1~meV on liquid hydrogen at 15.6~K (which is dominated by the parahydrogen component) using neutron transmission measurements on the hydrogen target of the NPDGamma collaboration at the Spallation Neutron Source at Oak Ridge National Laboratory. The relationship between the neutron transmission measurement we perform and the total cross section is unambiguous, and the energy range accesses length scales where the pair correlation function is rapidly varying. At 1~meV our measurement is a factor of 3 below the data from previous work. We present evidence that these previous measurements of the hydrogen cross section, which assumed that the equilibrium value for the ratio of orthohydrogen and parahydrogen has been reached in the target liquid, were in fact contaminated with an extra non-equilibrium component of orthohydrogen. Liquid parahydrogen is also a widely-used neutron moderator medium, and an accurate knowledge of its slow neutron cross section is essential for the design and optimization of intense slow neutron sources. We describe our measurements and compare them with previous work.Comment: Edited for submission to Physical Review

    Relations between children’s metamemory and strategic performance: Time-varying covariates in early elementary school

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    Although much is known about the development of memory strategies and metamemory in childhood, evidence for linkages between these memory skills, either concurrently or over time, has been limited. Drawing from a longitudinal investigation of the development of memory, repeated assessments of children’s (N=107) strategy use and declarative metamemory were made, in order to examine the development of these skills and the relations between them over time. Latent curve models were used first to estimate the trajectories of children’s strategy use and metamemory and then to examine predictors of children’s performance in each of these domains. Children’s metamemory at the beginning of Grade 1 was linked to child- and home-level factors, whereas the development of both skills was related to maternal education level. Additional modeling of the longitudinal relations between strategic sorting and metacognitive knowledge indicated that metamemory at earlier time points was predictive of subsequent strategy use
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