212 research outputs found
Do Microcredit Loans Do What They Are Intended To Do? A Case Study of the Credit Village Microcredit Programme in China
© 2020 John Wiley & Sons, Ltd. The purpose of this study is to assess if the credit village is an effective way to develop a microcredit programme in China from the perspective of poverty reduction policy and risk monitoring. Cross-sectional household survey data from three credit villages in the Yunan County of China are analysed using 3SLS and IV probit models. The major finding is that the credit village loosens credit restrictions to some extent. However, it has no impact on educational expenditures, medical expenditures, long-term assets, short-term assets and women\u27s rights. It is our observation that the microcredit programme in China needs more innovation to become effective. © 2020 John Wiley & Sons, Ltd
A new view of k-essence
K-essence models, relying on scalar fields with non-canonical kinetic terms,
have been proposed as an alternative to quintessence in explaining the observed
acceleration of the Universe. We consider the use of field redefinitions to
cast k-essence in a more familiar form. While k-essence models cannot in
general be rewritten in the form of quintessence models, we show that in
certain dynamical regimes an equivalence can be made, which in particular can
shed light on the tracking behaviour of k-essence. In several cases, k-essence
cannot be observationally distinguished from quintessence using the homogeneous
evolution, though there may be small effects on the perturbation spectrum. We
make a detailed analysis of two k-essence models from the literature and
comment on the nature of the fine tuning arising in the models.Comment: 7 pages RevTeX4 file with four figures incorporate
Nonlinear Spinor Fields and its role in Cosmology
Different characteristic of matter influencing the evolution of the Universe
has been simulated by means of a nonlinear spinor field. Exploiting the spinor
description of perfect fluid and dark energy evolution of the Universe given by
an anisotropic Bianchi type-VI, VI, V, III, I or isotropic
Friedmann-Robertson-Walker (FRW) one has been studied. It is shown that due to
some restrictions on metric functions, initial anisotropy in the models Bianchi
type-VI, VI, V and III does not die away, while the anisotropic Bianchi
type-I models evolves into the isotropic one.Comment: 22 pages, 12 Figure
Interacting polytropic gas model of phantom dark energy in non-flat universe
By introducing the polytropic gas model of interacting dark energy, we obtain
the equation of state for the polytropic gas energy density in a non-flat
universe. We show that for even polytropic index by choosing
, one can obtain , which
corresponds to a universe dominated by phantom dark energy.Comment: 7 page
Beekeeping in Jalisco, México
The purpose of this study was to analyze the socioeconomic factors that influence the beekeeping process and describe the current situation in beekeeping technology development in the south and southeast regions of Jalisco. The study was conducted by reviewing secondary sources of documentary information and the primary information was obtained by means of a survey, analyzing demographic, social, technological, and economic variables. From January to April 2011, a stratified sampling was conducted of six strata of beekeepers, with a final sampling of 183 beekeepers. We applied a frequency analysis, ANOVA (Waller-Duncan), and contingency tables (χ2). The average age observed for the beekeepers was 47 years, with fewer women participating in the activity, and an above national average level of education. The majority keep their apiaries in rented premises, a high percentage outside the municipality where they live. The honey obtained is multiflora and the main harvest is in the autumn, with a honey yield per hive below the national average. A number of problems affect the production sector including environmental factors, production costs, and varroa. We observed little diversification; in addition to honey only beeswax is recovered, and only a minority keep a record of production costs. There is wide participation in beekeeping associations and in training provided by different public and private bodies. There is a willingness to adopt new technologies and equipment for honey production with good practice standards
Nonlinear spinor field in Bianchi type-I Universe filled with viscous fluid: numerical solutions
We consider a system of nonlinear spinor and a Bianchi type I gravitational
fields in presence of viscous fluid. The nonlinear term in the spinor field
Lagrangian is chosen to be , with being a self-coupling
constant and being a function of the invariants an constructed from
bilinear spinor forms and . Self-consistent solutions to the spinor and
BI gravitational field equations are obtained in terms of , where
is the volume scale of BI universe. System of equations for and \ve,
where \ve is the energy of the viscous fluid, is deduced. This system is
solved numerically for some special cases.Comment: 15 pages, 4 figure
K-essence and the coincidence problem
K-essence has been proposed as a possible means of explaining the coincidence
problem of the Universe beginning to accelerate only at the present epoch. We
carry out a comprehensive dynamical systems analysis of the k-essence models
given so far in the literature. We numerically study the basin of attraction of
the tracker solutions and we highlight the behaviour of the field close to
sound speed divergences. We find that, when written in terms of parameters with
a simple dynamical interpretation, the basins of attraction represent only a
small region of the phase space.Comment: 5 pages RevTeX4 file with two figures incorporated. Minor changes to
match PRD accepted versio
Holographic dark energy in a non-flat universe with Granda-Oliveros cut-off
Motivated by Granda and Oliveros (GO) model, we generalize their work to the
non-flat case. We obtain the evolution of the dark energy density, the
deceleration and the equation of state parameters for the holographic dark
energy model in a non-flat universe with GO cut-off. In the limiting case of a
flat universe, i.e. , all results given in GO model are obtained.Comment: 11 pages, 5 figure
Spinors, Inflation, and Non-Singular Cyclic Cosmologies
We consider toy cosmological models in which a classical, homogeneous, spinor
field provides a dominant or sub-dominant contribution to the energy-momentum
tensor of a flat Friedmann-Robertson-Walker universe. We find that, if such a
field were to exist, appropriate choices of the spinor self-interaction would
generate a rich variety of behaviors, quite different from their widely studied
scalar field counterparts. We first discuss solutions that incorporate a stage
of cosmic inflation and estimate the primordial spectrum of density
perturbations seeded during such a stage. Inflation driven by a spinor field
turns out to be unappealing as it leads to a blue spectrum of perturbations and
requires considerable fine-tuning of parameters. We next find that, for simple,
quartic spinor self-interactions, non-singular cyclic cosmologies exist with
reasonable parameter choices. These solutions might eventually be incorporated
into a successful past- and future-eternal cosmological model free of
singularities. In an Appendix, we discuss the classical treatment of spinors
and argue that certain quantum systems might be approximated in terms of such
fields.Comment: 12 two-column pages, 3 figures; uses RevTeX
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