7,156 research outputs found

    Lessons From Mapping Jewish Education

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    Based on two previous reports on the foundation's support for Jewish education, explores implications and lessons for the role of national agencies and the need for long-term planning, fundraising, innovation, adapting to local contexts, and other issues

    Classes of complex networks defined by role-to-role connectivity profiles

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    Interactions between units in phyical, biological, technological, and social systems usually give rise to intrincate networks with non-trivial structure, which critically affects the dynamics and properties of the system. The focus of most current research on complex networks is on global network properties. A caveat of this approach is that the relevance of global properties hinges on the premise that networks are homogeneous, whereas most real-world networks have a markedly modular structure. Here, we report that networks with different functions, including the Internet, metabolic, air transportation, and protein interaction networks, have distinct patterns of connections among nodes with different roles, and that, as a consequence, complex networks can be classified into two distinct functional classes based on their link type frequency. Importantly, we demonstrate that the above structural features cannot be captured by means of often studied global properties

    Satellites of Simulated Galaxies: survival, merging, and their relation to the dark and stellar halos

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    We study the population of satellite galaxies formed in a suite of N-body/gasdynamical simulations of galaxy formation in a LCDM universe. We find little spatial or kinematic bias between the dark matter and the satellite population. The velocity dispersion of the satellites is a good indicator of the virial velocity of the halo: \sigma_{sat}/V_{vir}=0.9 +/- 0.2. Applied to the Milky Way and M31 this gives V_{vir}^{MW}=109 +/- 22$ km/s and V_{vir}^{M31} = 138 +/- 35 km/s, respectively, substantially lower than the rotation speed of their disk components. The detailed kinematics of simulated satellites and dark matter are also in good agreement. By contrast, the stellar halo of the simulated galaxies is kinematically and spatially distinct from the population of surviving satellites. This is because the survival of a satellite depends on mass and on time of accretion; surviving satellites are biased toward low-mass systems that have been recently accreted by the galaxy. Our results support recent proposals for the origin of the systematic differences between stars in the Galactic halo and in Galactic satellites: the elusive ``building blocks'' of the Milky Way stellar halo were on average more massive, and were accreted (and disrupted) earlier than the population of dwarfs that has survived self-bound until the present.Comment: 13 pages, 11 figures, MNRAS in press. Accepted version with minor changes. Version with high resolution figures available at: http://www.astro.uvic.ca/~lsales/SatPapers/SatPapers.htm

    Mapping Professional Development for Jewish Educators

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    Describes the desirable and necessary characteristics of effective professional development in Jewish education, the various opportunities and approaches available to Jewish educators, and possibilities for future expansion and improvement

    Density distribution of particles upon jamming after an avalanche in a 2D silo

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    We present a complete analysis of the density distribution of particles in a two dimensional silo after discharge. Simulations through a pseudo-dynamic algorithm are performed for filling and subsequent discharge of a plane silo. Particles are monosized hard disks deposited in the container and subjected to a tapping process for compaction. Then, a hole of a given size is open at the bottom of the silo and the discharge is triggered. After a clogging at the opening is produced, and equilibrium is restored, the final distribution of the remaining particles at the silo is analyzed by dividing the space into cells with different geometrical arrangements to visualize the way in which the density depression near the opening is propagated throughout the system. The different behavior as a function of the compaction degree is discussed.Comment: 11 pages, 10 figure

    Mapping Jewish Education: The National Picture

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    Based on interviews as well as a database of Jewish educational organizations, foundations, and programs, examines their accomplishments, challenges, future directions, and links within a Jewish educational system. Highlights the role of foundations

    Sharing of hand kinematic synergies across subjects in daily living activities

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    The motor system is hypothesised to use kinematic synergies to simplify hand control. Recent studies suggest that there is a large set of synergies, sparse in degrees of freedom, shared across subjects, so that each subject performs each action with a sparse combination of synergies. Identifying how synergies are shared across subjects can help in prostheses design, in clinical decision-making or in rehabilitation. Subject-specific synergies of healthy subjects performing a wide number of representative daily living activities were obtained through principal component analysis. To make synergies comparable between subjects and tasks, the hand kinematics data were scaled using normative range of motion data. To obtain synergies sparse in degrees of freedom a rotation method that maximizes the sum of the variances of the squared loadings was applied. Resulting synergies were clustered and each cluster was characterized by a core synergy and different indexes (prevalence, relevance for function and within-cluster synergy similarity), substantiating the sparsity of synergies. The first two core synergies represent finger flexion and were present in all subjects. The remaining core synergies represent coordination of the thumb joints, thumb-index joints, palmar arching or fingers adduction, and were employed by subjects in different combinations, thus revealing different subject-specific strategies

    Lattice dynamics and reduced thermal conductivity of filled skutterudites

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    The great reduction in thermal conductivity of skutterudites upon filling the ``void'' sites with Rare Earth (RE) ions is key to their favorable thermoelectric properties but remains to be understood. Using lattice dynamic models based on first principles calculations, we address the most popular microscopic mechanism, reduction via rattling ions. The model withstands inelastic neutron scattering and specific heat measurements, and refutes hypotheses of an anharmonic RE potential and of two distinct localized RE vibrations of disparate frequencies. It does indicate a strong hybridization between bare La vibrations and certain Sb-like phonon branches, suggesting anharmonic scattering by harmonic RE motions as an important mechanism for suppression of heat conductivity.Comment: modified version resubmitted to PRB. Results unchanged, text changed substantiall

    Micro-bias and macro-performance

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    We use agent-based modeling to investigate the effect of conservatism and partisanship on the efficiency with which large populations solve the density classification task--a paradigmatic problem for information aggregation and consensus building. We find that conservative agents enhance the populations' ability to efficiently solve the density classification task despite large levels of noise in the system. In contrast, we find that the presence of even a small fraction of partisans holding the minority position will result in deadlock or a consensus on an incorrect answer. Our results provide a possible explanation for the emergence of conservatism and suggest that even low levels of partisanship can lead to significant social costs.Comment: 11 pages, 5 figure

    Avaliação do desempenho produtivo de bovinos de corte, em pastos puros e consorciados com o amendoim forrageiro cultivar Mandobi, no Acre.

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    Objetivou-se avaliar o efeito da consorciação de pastos de Brachiaria humidicola com Arachis pintoi cv. Mandobi sobre o desempenho produtivo de novilhos Nelore. O experimento foi realizado em uma fazenda particular no Estado do Acre, de novembro de 2013 a fevereiro de 2014. As unidades experimentais foram seis piquetes de 1,42 ha cada, em um delineamento inteiramente casualizado, com dois tratamentos e três repetições. Foram utilizados seis novilhos Nelore, não castrados, com idade e peso médio iniciais de 16 meses e 282 kg, como testes. Novilhos adicionais foram alocados ou retirados dos piquetes para a manutenção da altura do pasto, em 15 cm. Os animais foram pesados a cada 28 dias, após um jejum de 16 horas, para determinar o ganho de peso médio diário (GMD). A capacidade de suporte foi calculada de acordo com o peso médio e número de animais/dia em cada unidade experimental. A produtividade animal foi calculada com base no GMD dos animais teste e o número de animais/dia utilizados durante todo experimento. As médias dos quadrados mínimos foram comparadas usando o teste de Tukey com 5% de probabilidade. A taxa de lotação durante o período experimental foi de 3,97 UA/ha nos pastos consorciado e 3,81 nos pastos puros (P = 0,8255). O ganho de peso médio diário dos animais foi 17,7% superior (P = 0,0465) para o pasto consorciado (0,597 x 0,479 kg/animal/dia) e a produtividade animal aumentou 18,7% (P = 0,1010) pelo uso de A. pintoi cv. Mandobi (330 kg/ha x 278 kg/ha). Este estudo mostra que apenas 7,7% desta leguminosa em pastagens consorciadas com Brachiaria humidicola pode afetar positivamente a produtividade animal
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