2,295 research outputs found

    3-Ethyl-6-(4-fluoro­phen­yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thia­diazine

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    In the title compound, C12H11FN4S, the thia­diazine ring adopts a twist-boat conformation. The dihedral angle between the triazolothia­diazine system and the benzene ring is 10.54 (9)°. The crystal structure is characterized by C—H⋯N hydrogen bonds. The crystal packing also exhibits π–π inter­actions, with a centroid–centroid distance of 3.6348 (15) Å

    Preon Prophecies by the Standard Model

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    The Standard Model of quarks and leptons is, at first sight, nothing but a set of {\it ad hoc} rules, with no connections, and no clues to their true background. At a closer look, however, there are many inherent prophecies that point in the same direction: {\it Compositeness} in terms of three stable preons.Comment: 13 pages, 8 eps-figures, invited talk at Beyond the Desert '03, Schloss Ringberg, Bavaria, June 2003; to be published in the Proceeding

    Environmental and genetic influences on neurocognitive development: the importance of multiple methodologies and time-dependent intervention

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    Genetic mutations and environmental factors dynamically influence gene expression and developmental trajectories at the neural, cognitive, and behavioral levels. The examples in this article cover different periods of neurocognitive development—early childhood, adolescence, and adulthood—and focus on studies in which researchers have used a variety of methodologies to illustrate the early effects of socioeconomic status and stress on brain function, as well as how allelic differences explain why some individuals respond to intervention and others do not. These studies highlight how similar behaviors can be driven by different underlying neural processes and show how a neurocomputational model of early development can account for neurodevelopmental syndromes, such as autism spectrum disorders, with novel implications for intervention. Finally, these studies illustrate the importance of the timing of environmental and genetic factors on development, consistent with our view that phenotypes are emergent, not predetermined

    1-(1-Benzofuran-2-yl)-3-(4-chloro­phen­yl)prop-2-en-1-one

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    In the title compound, C17H11ClO2, the benzofuran ring system is almost planar (r.m.s. deviation = 0.011 Å) and forms a dihedral angle of 10.53 (6)° with the chloro­phenyl ring. No significant inter­molecular inter­actions are observed

    Network Growth with Feedback

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    Existing models of network growth typically have one or two parameters or strategies which are fixed for all times. We introduce a general framework where feedback on the current state of a network is used to dynamically alter the values of such parameters. A specific model is analyzed where limited resources are shared amongst arriving nodes, all vying to connect close to the root. We show that tunable feedback leads to growth of larger, more efficient networks. Exact results show that linear scaling of resources with system size yields crossover to a trivial condensed state, which can be considerably delayed with sublinear scaling.Comment: 4 pages, 4 figure

    Long and short paths in uniform random recursive dags

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    In a uniform random recursive k-dag, there is a root, 0, and each node in turn, from 1 to n, chooses k uniform random parents from among the nodes of smaller index. If S_n is the shortest path distance from node n to the root, then we determine the constant \sigma such that S_n/log(n) tends to \sigma in probability as n tends to infinity. We also show that max_{1 \le i \le n} S_i/log(n) tends to \sigma in probability.Comment: 16 page
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