15,899 research outputs found

    Word Generation in Boston Public Schools: Natural History of a Literacy Intervention

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    Describes a program to teach high-frequency academic vocabulary and discourses skills, promote effective teaching strategies for vocabulary, comprehension, and discussion, and facilitate faculty collaboration; its implementation; and evaluation results

    Hedging Options in a GARCH Environment: Testing the Term Structure of Stochastic Volatility Models

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    This paper develops a methodology for testing the term structure of volatility forecasts derived from stochastic volatility models, and implements it to analyze models of S&P 500 index volatility. Volatility models are compared by their ability to hedge options positions sensitive to the term structure of volatility. Overall, the most effective hedge is a Black-Scholes (BS) delta-gamma hedge, while the BS delta-vega hedge is the least effective. The most successful volatility hedge is GARCH components delta-gamma, suggesting that the GARCH components estimate of the term structure of volatility is most accurate. The success of the BS delta-gamma hedge may be due to mispricing in the options market over the sample period.

    N-Ferrocenylmethyl-2-(3-methylstyryl)-N’-methylbenzimidazolium hexafluorophosphate

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    In the title compound, [Fe(C5H5)(C23H22N2)]PF6, the F atoms of the [PF6]- anion are disordered over four different orientations with equal occupancies. In the cation, the five-membered imidazolium ring forms dihedral angles of 71.48 (10) and 19.83 (10)° with the substituted C5H4 ring and the benzene ring of the styryl group, respectively. In the crystal structure, there is a significant C-H...[pi]([eta]5-C5H4) interaction

    2-(3,5-Dimethylbenzene)-1-ferrocenylmethyl-1H-1,3-benzimidazole

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    In the title molecule, [Fe(C5H5)(C21H19N2)], the five-membered imidazole ring forms dihedral angles of 88.61 (8) and 42.15 (6)° with the substituted cyclopentadienyl and dimethyl-substituted benzene rings, respectively. In the crystal structure, there is an Nsp2...H contact and a modest C-H...[pi](arene) interaction involving the benzene ring of the benzimidizole system

    Morphometric approach to many-body correlations in hard spheres

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    We model the thermodynamics of local structures within the hard sphere liquid at arbitrary volume fractions through the \textit{morphometric} calculation of nn-body correlations. We calculate absolute free energies of local geometric motifs in excellent quantitative agreement with molecular dynamics simulations across the liquid and supercooled liquid regimes. We find a bimodality in the density library of states where five-fold symmetric structures appear lower in free energy than four-fold symmetric structures, and from a single reaction path predict a relaxation barrier which scales linearly in the compressibility factor. The method provides a new route to assess changes in the free energy landscape at volume fractions dynamically inaccessible to conventional techniques.Comment: 6+17 pages, 3 figure
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