1,601 research outputs found

    "You Can't Study if you're Hungry" Report of a Parliamentary Delegation to Tanzania\ud

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    Confirmation of the detection of B-modes in the Planck polarization maps

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    One of the main problems for extracting the Cosmic Microwave Background (CMB) from submm/mm observations is to correct for the Galactic components, mainly synchrotron, free - free and thermal dust emission with the required accuracy. Through a series of papers, it has been demonstrated that this task can be fulfilled by means of simple neural networks with high confidence. The main purpose of this paper is to demonstrate that the CMB BB power spectrum detected in the Planck 2015 polarization maps is present in the improved Planck 2017 maps with higher signal-to-noise ratio. Two features have been detected in the EB power spectrum in the new data set, both with S/N ∟\sim4 . The origin of these features is most likely leakage from E to B with a level of about 1 per cent. This leakage gives no significant contribution to the detected BB power spectrum. The TB power spectrum is consistent with a zero signal. Altogether, the BB power spectrum is not consistent with the 'canonical' tensor-to-scalar models combined with gravitational lensing spectra. These results will give additional strong arguments for support to the proposed polarization satellite projects to follow up on the Planck mission .Comment: accepted for puplication in Astronomical Note

    Kinetics of exciton photoluminescence in type-II semiconductor superlattices

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    The exciton decay rate at a rough interface in type-II semiconductor superlattices is investigated. It is shown that the possibility of recombination of indirect excitons at a plane interface essentially affects kinetics of the exciton photoluminescence at a rough interface. This happens because of strong correlation between the exciton recombination at the plane interface and at the roughness. Expressions that relate the parameters of the luminescence kinetics with statistical characteristics of the rough interface are obtained. The mean height and length of roughnesses in GaAs/AlAs superlattices are estimated from the experimental data.Comment: 3 PostScript figure

    Using Evaluation to Improve and Promote America Reads

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    This report covers: Project Objectives; Collecting Data; Sample Instruments; Analyzing Data; and Using Evaluation Findings

    What works for Nutrition? Stories of success from Vietnam, Uganda and Kenya

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    This report discusses the drivers of progress in tackling multiple forms of malnutrition in these three countries: Vietnam, Uganda, and Kenya. It also identifies some of the challenges which pose as barriers to sustaining progress. Finally, it makes recommendations for key stakeholders such as governments of high burden countries, donor governments, development partners, and civil society, on their role to promote further success

    The Employment, Earnings, and Income of Less-Skilled Workers over the Business Cycle

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    In this paper, I examine the effect of business cycles on the employment, earnings, and income of persons in different demographic groups. I classify individuals by sex, education, and race. The analysis uses data from the Current Population Survey’s Outgoing Rotation Group data, covering the period 1979–1992, and March Annual Demographic File data, covering the period 1975–1997. Many different individual and family outcome measures are considered, including employment to population ratios, weekly earnings, hourly earnings, annual hours, annual earnings, family earnings, family transfer income, and total family income. The regression model is specified such that the key parameters measure how the labor market outcomes of less-skilled workers vary with the business cycle relative to the variability for high-skill groups. The analysis uses variation across MSAs in the timing and severity of shocks. The results consistently show that individuals with lower educational levels, nonwhites, and low-skill women experience greater cyclical fluctuation than high-skill men. These results are the most striking when examining comprehensive measures of labor force activity such as the likelihood of full-time, full-year work. Government transfers and the earnings of other family members decrease the differences between groups, resulting in more skill-group-neutral effects of business cycles on family income than on individual earnings. The paper examines the stability of these results by comparing evidence across the 1982 and 1992 recessions. The evidence suggests that the 1992 recession led to more uniform effects across skill groups than did earlier cycles.

    T>0 properties of the infinitely repulsive Hubbard model for arbitrary number of holes

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    Based on representations of the symmetric group SNS_N, explicit and exact Schr\"odinger equation is derived for U=∞U=\infty Hubbard model in any dimensions with arbitrary number of holes, which clearly shows that during the movement of holes the spin background of electrons plays an important role. Starting from it, at T=0 we have analyzed the behaviour of the system depending on the dimensionality and number of holes. Based on the presented formalism thermodynamic quantities have also been expressed using a loop summation technique in which the partition function is given in terms of characters of SNS_N. In case of the studied finite systems, the loop summation have been taken into account exactly up to the 14-th order in reciprocal temperature and the results were corrected in higher order based on Monte Carlo simulations. The obtained results suggest that the presented formalism increase the efficiency of the Monte Carlo simulations as well, because the spin part contribution of the background is automatically taken into account by the characters of SNS_N.Comment: 26 pages, 1 embedded ps figure; Phil. Mag. B (in press

    DEVELOPING, MODELLING AND MAPPING OF CRITICAL LOADS AND THEIR INPUT DATA STATUS REPORT ON THE CALL FOR EUROPEAN CRITICAL LOADS ON ACIDIFICATION AND EUTROPHICATION

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    Programme (ICP) on the Modelling and Mapping of Critical Levels and Loads and Air Pollution Effects, Risks and Trends, with the assistance of the secretaria
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