14,336 research outputs found

    A Qualitative Study Using Community Cultural Wealth to Understand the Educational Experiences of Latino College Students

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    The Latino population is the largest minority group in the United States (Quijada & Alvarez, 2006) and has the highest high school dropout rate of any ethnic group (American Council on Education, 2008). If the U.S. is to compete in the global economy, it is important to understand factors that facilitate or hider the academic performance of Latino students. This qualitative study provides rich narratives on how Latino students used community cultural wealth, including knowledge, skills, abilities and networks, to excel in educational settings and overcome obstacles. A total of 15 individuals participated in the study. Findings suggest that Latino students overcome structural and cultural obstacles using various forms of community cultural wealth. In addition, the article provides recommendations based on participant’s experiences and previous research to increase Latino students’ success. It is the hope of the authors that findings from the present study will provide insight into the factors that facilitate Latino student success

    Stability of nonlinear magnetic black holes

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    We study the stability of static spherically symmetric exact solutions of Einstein equations coupled with nonlinear electrodynamics, in the magnetic sector. These solutions satisfy the heuristic model proposed by Ashtekar-Corichi-Sudarsky for hairy black holes, meaning that the horizon mass is related to their Arnowitt-Deser-Misner (ADM) mass and to the corresponding particle-like solution. We test the unstability conjecture that emerges for hairy black holes and it turned out that it becomes confirmed except for the Einstein-Born-Infeld solutions.Comment: 7 pages, submitted to Phys. Rev. D.In this version the stability of the solitonic solutions is addresse

    Downwash-Aware Trajectory Planning for Large Quadrotor Teams

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    We describe a method for formation-change trajectory planning for large quadrotor teams in obstacle-rich environments. Our method decomposes the planning problem into two stages: a discrete planner operating on a graph representation of the workspace, and a continuous refinement that converts the non-smooth graph plan into a set of C^k-continuous trajectories, locally optimizing an integral-squared-derivative cost. We account for the downwash effect, allowing safe flight in dense formations. We demonstrate the computational efficiency in simulation with up to 200 robots and the physical plausibility with an experiment with 32 nano-quadrotors. Our approach can compute safe and smooth trajectories for hundreds of quadrotors in dense environments with obstacles in a few minutes.Comment: 8 page

    Staurosira magallanesica, a replacement name for Staurosira patagonica

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    Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales described a new species found in material of Maar Magallanes, Patagonia, Argentina and other lakes in southern Patagonia. This new species was analysed in detail by light and electron microscopy and a comprehensive description is given in Garcia et al. (2017: 107, 114, figs 2-45). However, this name is a later homonym of Staurosira patagonica Cleve, 1882. If we compare our species to Cleve’s illustration (Cleve 1882: pl. 16: fig. 13), we can easily differentiate the two by their general valve outline and morphometric data. As pointed out by Garcia et al. (2017), re-examination of the type material of members of the Fragilariaceae is needed to confirm identities, establish taxonomic boundaries and to facilitate identification, and this is also the case with Staurosira patagonica Cleve. A new name is, however, required for Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales as it is an illegitimate name: Staurosira magallanesica M.L.Garcia, Maidana, Ector & E.Morales nom. nov. Replaced synonym: Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales Nova Hedwigia, Beiheft 146: 107, 114, figs 2-45, 2017, nom illeg., non Staurosira patagonica Cleve 1882 Öfversigt af Kongliga Svenska Vetenskaps-Akademiens Förhandlingar 38(10): 13, pl. 16: fig. 13, 1882 ‘1881’. Etymology: we have derived the specific epithet from the name of the paleolake Maar Magallanes where this new species was found for the first time by N.I. Maidana (Maidana & Corbella 1997).Fil: García, María Luján. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Maidana, Nora Irene. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Ector, Luc. Luxembourg Institute of Science and Technology; LuxemburgoFil: Morales, E. A.. Universidade de Évora; Portuga

    The 1P quarkonium fine splittings at NLO

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    We calculate the 1P heavy quarkonium fine splittings at NLO and discuss the impact of the calculation on the chi_b(1P) splittings.Comment: 10 pages, 3 figure

    Intrinsic alignments of group and cluster galaxies in photometric surveys

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    Intrinsic alignments of galaxies have been shown to contaminate weak gravitational lensing observables on linear scales, r>r> 10 h1h^{-1}Mpc, but studies of alignments in the non-linear regime have thus far been inconclusive. We present an estimator for extracting the intrinsic alignment signal of galaxies around stacked clusters of galaxies from multiband imaging data. Our estimator removes the contamination caused by galaxies that are gravitationally lensed by the clusters and scattered in redshift space due to photometric redshift uncertainties. It uses posterior probability distributions for the redshifts of the galaxies in the sample and it is easily extended to obtain the weak gravitational lensing signal while removing the intrinsic alignment contamination. We apply this algorithm to groups and clusters of galaxies identified in the Sloan Digital Sky Survey `Stripe 82' coadded imaging data over 150\sim 150 deg2^2. We find that the intrinsic alignment signal around stacked clusters in the redshift range 0.1<z<0.40.1<z<0.4 is consistent with zero. In terms of the tidal alignment model of Catelan et al. (2001), we set joint constraints on the strength of the alignment and the bias of the lensing groups and clusters on scales between 0.1 and 10h110\,h^{-1} Mpc, bLC1ρcrit=214+14×104b_LC_1\rho_{\rm crit} = -2_{-14}^{+14} \times 10^{-4}. This constrains the contamination fraction of alignment to lensing signal to the range between [18,23][-18,23] per cent below scales of 1 h1h^{-1} Mpc at 95 per cent confidence level, and this result depends on our photometric redshift quality and selection criteria used to identify background galaxies. Our results are robust to the choice of photometric band in which the shapes are measured (ii and rr) and to centring on the Brightest Cluster Galaxy or on the geometrical centre of the clusters.Comment: 30 pages, 16 figures, published in MNRA

    Model-independent Study of Electric Dipole Transitions in Quarkonium

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    The paper contains a systematic, model-independent treatment of electric dipole (E1) transitions in heavy quarkonium. Within the effective field theory framework of potential non-relativistic QCD (pNRQCD), we derive the complete set of relativistic corrections of relative order v^2 both for weakly and strongly-coupled quarkonia. The result supports and complements former results from potential model calculations.Comment: 42 pages, 9 figure

    The three-quark static potential in perturbation theory

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    We study the three-quark static potential in perturbation theory in QCD. A complete next-to-leading order calculation is performed in the singlet, octets and decuplet channels and the potential exponentiation is demonstrated. The mixing of the octet representations is calculated. At next-to-next-to-leading order, the subset of diagrams producing three-body forces is identified in Coulomb gauge and its contribution to the potential calculated. Combining it with the contribution of the two-body forces, which may be extracted from the quark-antiquark static potential, we obtain the complete next-to-next-to-leading order three-quark static potential in the colour-singlet channel.Comment: 36 pages, 11 figures, version published in Phys.Rev.

    Assessing Judicial Efficiency of Egyptian First Instance Courts: A DEA Analysis

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    Egypt started a recent judicial reform program in 2007, which can be considered the first ever since the establishment of the National Egyptian Judicial System in 1952. It focuses mainly on solving organizational problems within First Instance Courts (FIC), as they form the active cell of the Egyptian judicial system. However the efficiency of FICs is still doubtable to a large extent. This paper provides for the first time an efficiency analysis of 22 FICs in Egypt using the technique of Data Envelop Analysis (DEA). The main strength of this study is to consider the number of computers per court, as none of the previous papers on court efficiency has included a capital variable when defining their court production function before. Our results show that there are no significant differences observed in terms of management efficiency between the civil and criminal FICs, however criminal FICs districts are superior with respect to their corresponding civil districts in terms of program efficiency.Egyptian Judicial System; Efficiency; Data envelopment analysis
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