6,614 research outputs found
Millions fed: Proven successes in agricultural development
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 in covariant quark model
We study the leptonic and semileptonic -meson decays ( and )
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: ,
and
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
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,
() spectroscopy using Cornell potential
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 (, ) and confinement strength
(, ). The spin hyperfine, spin-orbit and tensor
components of the one gluon exchange interaction are computed perturbatively to
determine the mass spectra of excited , , and 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 meson without additional parameters. The
computed electromagnetic transition widths of heavy quarkonia and mesons
are in tune with available experimental data and other theoretical approaches
Superconductivity in 2-2-3 system Y2Ba2Cu2O(8+delta)
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
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
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
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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