2,031 research outputs found

    The Kandhkelgaon Story: a bold bid by women in Kandhkelgaon Village, Saintala Block, Bolangir District, to break out of their poverty trap

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    One third of the people on earth who are described as living in absolute poverty are found today in India. “These people,” says Mr B K Satpathy, “are caught in a poverty trap’.” “Poverty trap?” we ask. “These are creative weavers; their cloth has a distinctive style, but those who supply their thread also take away and sell the cloth, paying just a small labor cost for each saree. If they are skilled and work hard this amounts to only 25-30 rupees (60-70 US cents) per day.” Under this arrangement, weaving does not provide enough to live on, and people are seeking ways to escape their entrapment in poverty. (Pdf contains 6 pages)

    Supercell studies of the Fermi surface changes in the electron-doped superconductor LaFeAsO1x_{1-x}Fx_x

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    We study the changes in the Fermi surface with electron doping in the LaFeAsO1x_{1-x}Fx_x superconductors with density-functional supercell calculations using the linearized augmented planewave (LAPW) method. The supercell calculations with explicit F substitution are compared with those obtained from the virtual crystal approximation (VCA) and from a simple rigid band shift. We find significant differences between the supercell results and those obtained from the rigid-band shift with electron doping, although quite remarkably the supercell results are in good agreement with the virtual crystal approximation (VCA) where the nuclear charges of the O atoms are slightly increased to mimic the addition of the extra electrons. With electron doping, the two cylindrical hole pockets along ΓZ\Gamma-Z shrink in size, and the third hole pocket around ZZ disappears for an electron doping concentration in excess of about 7-8%, while the two elliptical electron cylinders along MAM-A expand in size. The spin-orbit coupling does not affect the Fermi surface much except to somewhat reduce the size of the third hole pocket in the undoped case. We find that with the addition of the electrons the antiferromagnetic state becomes energetically less stable as compared to the nonmagnetic state, indicating that the electron doping may provide an extra degree of stability to the formation of the superconducting ground state.Comment: 7 pages, 8 figure

    CFD-based process optimization of a dissolved air flotation system for drinking water production

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    Dissolved air flotation (DAF) has received more attention recently as a separation technique in both drinking water as well as wastewater treatment. However, the process as well as the preceding flocculation step is complex and not completely understood. Given the multiphase nature of the process, fluid dynamics studies are important to understand and optimize the DAF system in terms of operation and design. The present study is intended towards a comprehensive computational analysis for design optimization of the treatment plant in Kluizen, Belgium. Setting up the modelling framework involving the multiphase flow problem is briefly discussed. 3D numerical simulations on a scaled down model of the DAF design were analysed. The flow features give better confidence, but the flocs escape through the outlet still prevails which is averse to the system performance. In order to improve the performance and ease of maintenance, design modifications have been proposed by using a perforated tube for water extraction and are found to be satisfactory. The discussion is further reinforced through validating the numerical model against the experimental findings for stratified flow conditions

    On the smoothness of multi-M2 brane horizons

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    We calculate the degree of horizon smoothness of multi- M2M2-brane solution with branes along a common axis. We find that the metric is generically only thrice continuously differentiable at any of the horizons. The four-form field strength is found to be only twice continuously differentiable. We work with Gaussian null-like co-ordinates which are obtained by solving geodesic equations for multi-M2M2 brane geometry. We also find different, exact co-ordinate transformations which take the metric from isotropic co-ordinates to co-ordinates in which metric is thrice differentiable at the horizon. Both methods give the same result that the multi-M2M2 brane metric is only thrice continuously differentiable at the horizon.Comment: 24 pages, reference added, modified equation for non-singularity of metri

    Photoinduced magnetism in the ferromagnetic semiconductors

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    We study the enhancement of the magnetic transition temperature TcT_c due to incident light in ferromagnetic semiconductors such as EuS. The photoexcited carriers mediate an extra ferromagnetic interaction due to the coupling with the localized magnetic moments. The Hamiltonian consists of a Heisenberg model for the localized moments and an interaction term between the photoexcited carriers and the localized moments. The model predicts a small enhancement of the transition temperature in semi-quantitative agreement with the experiments.Comment: 5 pages, 5 figure

    Sensors in your clothes: Design and development of a prototype

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    Wearable computing is fast advancing as a preferred approach for integrating software solutions not only in our environment, but also in our everyday garments to exploit the numerous information sources we constantly interact with. This paper explores this context further by showing the possible use of wearable sensor technology for information critical information systems, through the design and development of a proof-of-concept prototyp

    Recursion and Path-Integral Approaches to the Analytic Study of the Electronic Properties of C60C_{60}

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    The recursion and path-integral methods are applied to analytically study the electronic structure of a neutral C60C_{60} molecule. We employ a tight-binding Hamiltonian which considers both the ss and pp valence electrons of carbon. From the recursion method, we obtain closed-form {\it analytic} expressions for the π\pi and σ\sigma eigenvalues and eigenfunctions, including the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) states, and the Green's functions. We also present the local densities of states around several ring clusters, which can be probed experimentally by using, for instance, a scanning tunneling microscope. {}From a path-integral method, identical results for the energy spectrum are also derived. In addition, the local density of states on one carbon atom is obtained; from this we can derive the degree of degeneracy of the energy levels.Comment: 19 pages, RevTex, 6 figures upon reques

    Electronic Raman scattering and photoluminescence from La0.7_{0.7}Sr0.3_{0.3}MnO3_3 exhibiting giant magnetoresistance

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    Raman and Photoluminescence (PL) experiments on correlated metallic La0.7_{0.7}Sr0.3_{0.3}MnO3_{3} have been carried out using different excitation wavelengths as a function of temperature from 15 K to 300 K. Our data suggest a Raman mode centered at 1800 cm1^{-1} and a PL band at 2.2 eV. The intensities of the two peaks decrease with increasing temperature. The Raman mode can be attributed to a plasmon excitation whose frequency and linewidths are consistent with the measured resistivities. The PL involves intersite electronic transitions of the manganese ions.Comment: 10 pages + 4 eps figures, Revtex 3.0, figures available on reques
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