1,209 research outputs found

    Sen and the art of educational maintenance: evidencing a capability, as opposed to an effectiveness, approach to schooling

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    There are few more widely applied terms in common parlance than ‘capability’. It is used (inaccurately) to represent everything from the aspiration to provide opportunity to notions of innate academic ability, with everything in between claiming apostolic succession to Amartya Sen, who (with apologies to Aristotle) first developed the concept. This paper attempts to warrant an adaptation of Sen’s capability theory to schooling and schooling policy, and to proof his concepts in the new setting using research involving 100 pupils from 5 English secondary schools and a schedule of questions derived from the capability literature. The findings suggest that a capability approach can provide an alternative to the dominant Benthamite school effectiveness paradigm, and can offer a sound theoretical framework for understanding better the assumed relationship between schooling and well-being

    Aspects of Dielectric Breakdown in a Model for Disordered Nonlinear Composites

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    We study dielectric breakdown in a semi-classical bond percolation model for nonlinear composite materials introduced by us and the related breakdown exponent near the percolation threshold in two dimensions. The breakdown exponent after doing finite size scaling analysis is found to be tBt_B \simeq 1.42. We discuss in detail the differences in our model from the traditional models for dielectric breakdown and argue that our result seems to be different from the standard result of 4/3 obtained in the previous models.Comment: 20 pages, LaTex file (6 postscript figures included

    Adsorbent Carbon Fabrics : New Generation Armour for Toxic Chemicals

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    Activated carbon in the form of a regular fabric obtained using viscose rayon precursor is a new generation adsorbent material having superior sorptional properties and is finding varied defence applications. Carbonisation and activation mechanisms and properties and applications of adsorbent carbort fibres made from viscose rayon precursor are reviewed in this paper

    Common origin of no-cloning and no-deleting principles - Conservation of information

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    We discuss the role of the notion of information in the description of physical reality. We consider theories for which dynamics is linear with respect to stochastic mixing. We point out that the no-cloning and no-deleting principles emerge in any such theory, if law of conservation of information is valid, and two copies contain more information than one copy. We then describe the quantum case from this point of view.Comment: This paper is dedicated to Asher Peres on the occasion of his seventieth birthda

    An optimal network for passenger traffic

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    The optimal solution of an inter-city passenger transport network has been studied using Zipf's law for the city populations and the Gravity law describing the fluxes of inter-city passenger traffic. Assuming a fixed value for the cost of transport per person per kilometer we observe that while the total traffic cost decreases, the total wiring cost increases with the density of links. As a result the total cost to maintain the traffic distribution is optimal at a certain link density which vanishes on increasing the network size. At a finite link density the network is scale-free. Using this model the air-route network of India has been generated and an one-to-one comparison of the nodal degree values with the real network has been made.Comment: 5 pages, 4 figure

    On a coordinate independent description of string worldsheet theory

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    We study worldsheet conformal invariance for bosonic string propagating in a curved background using the hamiltonian formalism. In order to formulate the problem in a background independent manner we first rewrite the worldsheet theory in a language where it describes a single particle moving in an infinite-dimensional curved spacetime. This language is developed at a formal level without regularizing the infinite-dimensional traces. Then we adopt DeWitt's (Phys.Rev.85:653-661,1952) coordinate independent formulation of quantum mechanics in the present context. Given the expressions for the classical Virasoro generators, this procedure enables us to define the coordinate invariant quantum analogues which we call DeWitt-Virasoro generators. This framework also enables us to calculate the invariant matrix elements of an arbitrary operator constructed out of the DeWitt-Virasoro generators between two arbitrary scalar states. Using these tools we further calculate the DeWitt-Virasoro algebra in spin-zero representation. The result is given by the Witt algebra with additional anomalous terms that vanish for Ricci-flat backgrounds. Further analysis need to be performed in order to precisely relate this with the beta function computation of Friedan and others. Finally, we explain how this analysis improves the understanding of showing conformal invariance for certain pp-wave that has been recently discussed using hamiltonian framework.Comment: 32 pages, some reorganization for more elaborate explanation, no change in conclusio

    Frequency-dependent (ac) Conduction in Disordered Composites: a Percolative Study

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    In a recent paper [Phys. Rev. B{\bf57}, 3375 (1998)], we examined in detail the nonlinear (electrical) dc response of a random resistor cum tunneling bond network (RRTNRRTN, introduced by us elsewhere to explain nonlinear response of metal-insulator type mixtures). In this work which is a sequel to that paper, we consider the ac response of the RRTNRRTN-based correlated RCRC (CRCCRC) model. Numerical solutions of the Kirchoff's laws for the CRCCRC model give a power-law exponent (= 0.7 near p=pcp = p_c) of the modulus of the complex ac conductance at moderately low frequencies, in conformity with experiments on various types of disordered systems. But, at very low frequencies, it gives a simple quadratic or linear dependence on the frequency depending upon whether the system is percolating or not. We do also discuss the effective medium approximation (EMAEMA) of our CRCCRC and the traditional random RCRC network model, and discuss their comparative successes and shortcomings.Comment: Revised and reduced version with 17 LaTeX pages plus 8 JPEG figure

    Evaluation of Chemical Protective Clothing: A Comparative Study of Breakthrough Times with Sulphur Mustard and a Simulant, 1,3-Dichloropropane

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    Carbon-coated non-woven fabrics were evaluated against vesicant sulphur mustard and l,3-dichloropropane (DCP). Breakthrough times of these chemicals were compared andfitted in a linear equation. A correlation, better than 95 per cent was obtained. It is recommended that DCP be used in the valuation and quality control of fabric in the chemical protective clothing manufacturing industries to reduce the exposure and risks of handling lethal chemicals. However,-the clothing may be challenged with actual CW agents to determine their protective potentials, in the laboratory. Diffusion coefficients for DCP were also computed from the breakthrough data for carbon-coated fabric of different grades
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