787 resultados para difference-in-differences


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The mechanism of beam splitting and principle of wide-field-of-view compensation of modified Savart polariscope in the wide-field-of-view polarization interference imaging spectrometer (WPIIS) are analyzed and discussed. Formulas for the lateral displacement and optical path difference (OPD) produced by the modified Savart polariscope are derived by ray-tracing method. The theoretical and practical guidance is thereby provided for the study, design, modulation, experiment and engineering of the polarization interference imaging spectrometers and other birefringent Fourier-transform spectrometers based on Savart polariscopes. (c) 2006 Elsevier B.V. All rights reserved.

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Covalent radii of the bonding elements have strong effects on the linear electro-optic coefficients of zinc blende crystals; these effects can be quantitatively determined by investigating the relation between the difference in the atomic sizes rho and the magnitude of the linear electro-optic tensor coefficient r(41). It is interesting to note that for the same cation Zn2+, Ga3+, or In3+ the magnitude of r(41) increases with increased covalent radius of the bonded anion r(beta). Especially with the increasing tendency of the parameter rho, the magnitude of r(41) of crystals that have a same cation will increase suddenly when the value of r(beta) becomes larger. (C) 1997 Academic Press.

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Martin Dowling, in what is perhaps the most comp[elling essay of the collection, deploys Slavoj Zizek's concept of the suture to think through the Other in Northern Irish cultural politics. Dowling identifies Ulster Scots as a suturing element--a cultural body harnessed to fill an inherent political "lack"--that stabilises Unionist identity in times of crisis. His essay considers more broadly the inherent limitations of the suture, whose logic functions like a "straightjacket on cultural life," and he proposes an alternative, genuinely open approach to Irish culture." From a review by Sarah Townsend in the Irish Literary Supplement, Spring 2010.

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In this article, the author critically examines a variety of approaches to multicultural education noted in integrated (mixed Catholic and Protestant) schools in Northern Ireland and considers their implications in the context of the wider debate around multiculturalism. She argues that educators should challenge sectarianism, but should also resist the essentialization of group identities.

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Determination of metal oxidation state under relevant working conditions is crucial to understand catalytic behaviour. The reduction behaviour of Pt and Re was evaluated simultaneously as a function of support and solvent in a pressurized reactor (autoclave). The bimetallic catalysts are used in selective hydrogenation of carboxylic acids and amides. Gas phase reduction reduced the metals more efficiently, in particular Pt.

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Background - Normal subjects have a negative nasal transmucosal potential difference (TPD) at rest which becomes more negative with exercise. Patients with cystic fibrosis have a more negative resting nasal TPD than controls. The present study was designed to determine the effects of exercise on the TPD of patients with cystic fibrosis.