6,614 research outputs found

    Millions fed: Proven successes in agricultural development

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    Learning from successes in agricultural development is now more urgent than ever. Progress in feeding the world’s billions has slowed, while the challenge of meeting future food needs remains enormous and is subject to new uncertainties in the global food and agricultural systems. In the late 1950s around a billion people were estimated to go hungry every day. Scientists, policymakers, farmers, and ordinary people initiated a concerted push to boost agricultural production and productivity in developing countries. Great strides were also made in improving the quality of food and the ability of vulnerable people to access food needed for survival. All these efforts have done more than just feed millions. They have also demonstrated that agriculture can be a key driver of growth and development for many of the world’s poorest countries.Developing countries, Food prices, Poverty reduction, Hunger, malnutrition, Agricultural research, Agricultural technology, food security, Agricultural development, Climate change, Agricultural markets, Agricultural policies, Science and technology,

    Decay DK()+ν{\mathit{D} \to} {{\mathit K}^{(*)}}{{\mathit \ell}^{+}}{{\mathit \nu}_{{{{\mathit \ell}}}}} in covariant quark model

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    We study the leptonic and semileptonic DD-meson decays (D+ν{{\mathit D} \to} {{\mathit \ell}^{+}}{{\mathit \nu}_{{{{\mathit \ell}}}}} and DK()+ν{\mathit{D} \to} {{\mathit K}^{(*)}}{{\mathit \ell}^{+}}{{\mathit \nu}_{{{{\mathit \ell}}}}}) in the framework of covariant quark model with built-in infrared confinement. We compute the required form factors in the entire kinematical momentum transfer region. The calculated form factors are used to evaluate the branching fractions of these transitions. We determine the following ratios of the partial widths: Γ(D0Ke+νe)/Γ(D+K0e+νe)=1.02\Gamma ({{\mathit D}^{0}} \rightarrow {{\mathit K}^{-}}{{\mathit e}^{+}}{{\mathit \nu}_{{e}}})/\Gamma({{\mathit D}^{+}} \rightarrow {{\overline{\mathit K}}^{0}}{{\mathit e}^{+}}{{\mathit \nu}_{{e}}}) = 1.02, Γ(D0Kμ+νμ)/Γ(D+K0μ+νμ)=0.99\Gamma({{\mathit D}^{0}} \rightarrow {{\mathit K}^{-}}{{\mathit \mu}^{+}}{{\mathit \nu}_{{\mu}}})/\Gamma({{\mathit D}^{+}} \rightarrow {{\overline{\mathit K}}^{0}}{{\mathit \mu}^{+}}{{\mathit \nu}_{{\mu}}}) = 0.99 and Γ(D+K0μ+νμ)/Γ(D+K0e+νe)=0.97\Gamma({{\mathit D}^{+}} \rightarrow {{\overline{\mathit K}}^{0}}{{\mathit \mu}^{+}}{{\mathit \nu}_{{\mu}}}) / \Gamma({{\mathit D}^{+}} \rightarrow {{\overline{\mathit K}}^{0}}{{\mathit e}^{+}}{{\mathit \nu}_{{e}}}) = 0.97 which are in close resemblance with the iso-spin invariance and experimental results.Comment: 20 pages, 6 tables, 7 figure

    Highlights from millions fed: Proven successes in agricultural development

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    Learning from successes in agricultural development is now more urgent than ever. Progress in feeding the world’s billions has slowed, while the challenge of meeting future food needs remains enormous and is subject to new uncertainties in the global food and agricultural systems. In the late 1950s around a billion people were estimated to go hungry every day. Scientists, policymakers, farmers, and ordinary people initiated a concerted push to boost agricultural production and productivity in developing countries. Great strides were also made in improving the quality of food and the ability of vulnerable people to access food needed for survival. All these efforts have done more than just feed millions. They have also demonstrated that agriculture can be a key driver of growth and development for many of the world’s poorest countries.Developing countries, Food prices, Poverty reduction, Hunger, malnutrition, Agricultural research, Agricultural technology, food security, Agricultural development, Climate change, Agricultural markets, Agricultural policies, Science and technology,

    QQˉQ\bar Q (Q{b,c}Q\in \{b, c\}) spectroscopy using Cornell potential

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    The mass spectra and decay properties of heavy quarkonia are computed in nonrelativistic quark-antiquark Cornell potential model. We have employed the numerical solution of Schr\"odinger equation to obtain their mass spectra using only four parameters namely quark mass (mcm_c, mbm_b) and confinement strength (AccˉA_{c\bar c}, AbbˉA_{b\bar b}). The spin hyperfine, spin-orbit and tensor components of the one gluon exchange interaction are computed perturbatively to determine the mass spectra of excited SS, PP, DD and FF states. Digamma, digluon and dilepton decays of these mesons are computed using the model parameters and numerical wave functions. The predicted spectroscopy and decay properties for quarkonia are found to be consistent with available experimental observations and results from other theoretical models. We also compute mass spectra and life time of the BcB_c meson without additional parameters. The computed electromagnetic transition widths of heavy quarkonia and BcB_c mesons are in tune with available experimental data and other theoretical approaches

    Superconductivity in 2-2-3 system Y2Ba2Cu2O(8+delta)

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    Researchers synthesized a new high T(sub c) 2-2-3 superconductor Y2Ba2Cu3O(8+delta) by a special preparation technique and characterized it by ac-susceptibility measurements. Diamagnetism and Meissner effect sets in at low fields and superconducting transition onsets at 90 K. The systematic investigation of the real and imaginary components of ac-susceptibility as a function of temperature and applied ac magnetic field reveals that the magnetic behavior is that of a granular type superconductor

    Masses and decay modes of charmonia using a confinement model

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    The masses of charmonium s and p-states, pseudoscalar and vector decay constants, leptonic, hadronic as well as radiative decay widths for charmonia have been computed in the framework of extended harmonic confinement model without any additional parameters. The outcome in comparison with other contemporary theoretical and experimental results is presented.Comment: Submitted to AIP for proceedings of International Workshop on Theoretical High Energy Physics held at IIT Roorkee, INDIA during 15-20 March, 200

    Coupled Supersymmetry and Ladder Structures Beyond the Harmonic Oscillator

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    The development of supersymmetric (SUSY) quantum mechanics has shown that some of the insights based on the algebraic properties of ladder operators related to the quantum mechanical harmonic oscillator carry over to the study of more general systems. At this level of generality, pairs of eigenfunctions of so-called partner Hamiltonians are transformed into each other, but the entire spectrum of any one of them cannot be deduced from this intertwining relationship in general -- except in special cases. In this paper, we present a more general structure that provides all eigenvalues for a class of Hamiltonians that do not factor into a pair of operators satisfying canonical commutation relations. Instead of a pair of partner Hamiltonians, we consider two pairs that differ by an overall shift in their spectrum. This is called coupled supersymmetry. In that case, we also develop coherent states and present some uncertainty principles which generalize the Heisenberg uncertainty principle. Coupled SUSY is explicitly realized by an infinite family of differential operators which admit orthonormal bases of eigenfunctions of generalized harmonic oscillators.Comment: 18 pages, 3 figure

    Correlation and prediction of dynamic human isolated joint strength from lean body mass

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    A relationship between a person's lean body mass and the amount of maximum torque that can be produced with each isolated joint of the upper extremity was investigated. The maximum dynamic isolated joint torque (upper extremity) on 14 subjects was collected using a dynamometer multi-joint testing unit. These data were reduced to a table of coefficients of second degree polynomials, computed using a least squares regression method. All the coefficients were then organized into look-up tables, a compact and convenient storage/retrieval mechanism for the data set. Data from each joint, direction and velocity, were normalized with respect to that joint's average and merged into files (one for each curve for a particular joint). Regression was performed on each one of these files to derive a table of normalized population curve coefficients for each joint axis, direction, and velocity. In addition, a regression table which included all upper extremity joints was built which related average torque to lean body mass for an individual. These two tables are the basis of the regression model which allows the prediction of dynamic isolated joint torques from an individual's lean body mass
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