1,334 research outputs found
Detection, Presence and Control of Seed-Borne Pests and Diseases of Trees with special reference to seeds of tropical and sub-tropical pines
Comparative Economic Analyses of Production Efficiency of Fadama II Catfish Beneficiaries with Non- Beneficiaries, Ogun State, Nigeria
This study compared the production efficiencies of Fadama II catfish farmers with non-beneficiaries in Ogun State. Stochastic Frontier Analysis and difference of mean statistics were used to analyze the primary data collected from two hundred and seventy (270) respondents among the 10 the Fadama participating Local Government Areas. The Maximum Likelihood Estimates (MLE) for the production function revealed that fertilizer (X1), quantity of feed (X3) and pond size (X7) at (p<0.01) determined the output of the beneficiaries and quantity of feed (X3) (p<0.05), fingerlings (X5)and pond size(X7) at (p<0.01) also have positive and significant effect on the output of the non-beneficiaries. The production inefficiency analysis revealed that farm efficiency would increase with increase in benefits status and extension contact(p<0.01). The MLE for cost function revealed that lime(X1) and fingerlings(X5) decreased the production cost, quantity of feed(X3) (p<0.1) increased the cost among the beneficiaries. while quantity of feed(X3), labour(X4) and pond size (X7) on the other hand increased the production cost among the non-beneficiaries. The cost inefficiency analysis further revealed that farming experience decreased the cost efficiency but increased the economic efficiency and the t-test showed significant difference (p<0.01) between the technical efficiencies of both sets of respondents. The beneficiaries are more efficient in terms of their technical, allocative and economic efficiencies than their non-beneficiary counterparts. The study recommends the expansion of the project scope to all the non-benefitting communities, provision of conducive environment for the establishment of ponds in all parts of the country to encourage more citizens to get into fish farming business and by extension, alleviate poverty status and un-employment in the state and country at large. The link between the Village Extension Agents (VEAs), Fadama Facilitators and the Fadama fish farmers should be strengthened through continual training and capacity building initiatives, if the objective of sustainably increasing Fadama farmersâ income is to be achieved. Keywords: National Fadama Development Project II (NFDPII), Beneficiaries, Non-beneficiaries, economic analysis, Production efficiency , catfish production, Ogun state, Nigeria
Gauge invariant reduction to the light-front
The problem of constructing gauge invariant currents in terms of light-cone
bound-state wave functions is solved by utilising the gauging of equations
method. In particular, it is shown how to construct perturbative expansions of
the electromagnetic current in the light-cone formalism, such that current
conservation is satisfied at each order of the perturbation theory.Comment: 12 pages, revtex
Low-temperature anomalous specific heat without tunneling modes: a simulation for a-Si with voids
Using empirical potential molecular dynamics we compute dynamical matrix
eigenvalues and eigenvectors for a 4096 atom model of amorphous silicon and a
set of models with voids of different size based on it. This information is
then employed to study the localization properties of the low-energy
vibrational states, calculate the specific heat C(T) and examine the
low-temperature properties of our models usually attributed to the presence of
tunneling states in amorphous silicon. The results of our calculations for C(T)
and "excess specific heat bulge" in the C(T)/T^3 vs. T graph for voidless a-Si
appear to be in good agreement with experiment; moreover our investigation
shows that the presence of localized low-energy excitations in the vibrational
spectrum of our models with voids strongly manifests itself as a sharp peak in
C(T)/T^3 dependence at T < 3K. To our knowledge this is the first numerical
simulation that provides adequate agreement with experiment for the very
low-temperature properties of specific heat in disordered systems within the
limits of harmonic approximation.Comment: 5 pages with 2 ps figures, submitted to PR
Optical cavity tests of Lorentz invariance for the electron
A hypothetical violation of Lorentz invariance in the electrons' equation of
motion (expressed within the Lorentz-violating extension of the standard model)
leads to a change of the geometry of crystals and thus shifts the resonance
frequency of an electromagnetic cavity. This allows experimental tests of
Lorentz invariance of the electron sector of the standard model. The material
dependence of the effect allows to separate it from an additional shift caused
by Lorentz violation in electrodynamics, and to place independent limits on
both effects. From present experiments, upper limits on Lorentz violation in
the electrons' kinetic energy term are deduced.Comment: 17 pages revte
The Topology and Size of the Universe from the Cosmic Microwave Background
We study the possibility that the universe has compact topologies T^3, T^2 x
R^1, or S^1 x R^2 using the seven-year WMAP data. The maximum likelihood 95%
confidence intervals for the size L of the compact direction are 1.7 < L/L_0 <
2.1, 1.8 < L/L_0 < 2.0, 1.2 < L/L_0 < 2.1 for the three cases, respectively,
where L_0=14.4 Gpc is the distance to the last scattering surface. An infinite
universe is compatible with the data at 4.3 sigma. We find using a Bayesian
analysis that the most probable universe has topology T^2 x R^1, with
L/L_0=1.9.Comment: Additional checks, Monte-Carlo skies, and study of dipole
contamination added. References added. 13 pages, 11 figure
Radiation induced oscillatory Hall effect in high mobility GaAs/AlGaAs devices
We examine the radiation induced modification of the Hall effect in high
mobility GaAs/AlGaAs devices that exhibit vanishing resistance under microwave
excitation. The modification in the Hall effect upon irradiation is
characterized by (a) a small reduction in the slope of the Hall resistance
curve with respect to the dark value, (b) a periodic reduction in the magnitude
of the Hall resistance, , that correlates with an increase in the
diagonal resistance, , and (c) a Hall resistance correction that
disappears as the diagonal resistance vanishes.Comment: 4 pages text, 4 color figure
Is weak temperature dependence of electron dephasing possible?
The first-principle theory of electron dephasing by disorder-induced two
state fluctuators is developed. There exist two mechanisms of dephasing. First,
dephasing occurs due to direct transitions between the defect levels caused by
inelastic electron-defect scattering. The second mechanism is due to violation
of the time reversal symmetry caused by time-dependent fluctuations of the
scattering potential. These fluctuations originate from an interaction between
the dynamic defects and conduction electrons forming a thermal bath. The first
contribution to the dephasing rate saturates as temperature decreases. The
second contribution does not saturate, although its temperature dependence is
rather weak, . The quantitative estimates based on the
experimental data show that these mechanisms considered can explain the weak
temperature dependence of the dephasing rate in some temperature interval.
However, below some temperature dependent on the model of dynamic defects the
dephasing rate tends rapidly to zero. The relation to earlier studies of the
dephasing caused by the dynamical defects is discussed.Comment: 14 pages, 6 figures, submitted to PR
Validation of the Virtual Reality Everyday Assessment Lab (VR-EAL):An immersive virtual reality neuropsychological battery with enhanced ecological validity
International audienceObjective: The assessment of cognitive functions such as prospective memory, episodic memory, attention, and executive functions benefits from an ecologically valid approach to better understand how performance outcomes generalize to everyday life. Immersive virtual reality (VR) is considered capable of simulating real-life situations to enhance ecological validity. The present study attempted to validate the Virtual Reality Everyday Assessment Lab (VR-EAL), an immersive VR neuropsychological battery, against an extensive paper-andpencil neuropsychological battery. Methods: Forty-one participants (21 females) were recruited: 18 gamers and 23 non-gamers who attended both an immersive VR and a paper-and-pencil testing session. Bayesian Pearson correlation analyses were conducted to assess construct and convergent validity of the VR-EAL. Bayesian t-tests were performed to compare VR and paper-and-pencil testing in terms of administration time, similarity to real life tasks (i.e., ecological validity), and pleasantness. Results: VR-EAL scores were significantly correlated with their equivalent scores on the paper-and-pencil tests. The participants' reports indicated that the VR-EAL tasks were significantly more ecologically valid and pleasant than the paper-and-pencil neuropsychological battery. The VR-EAL battery also had a shorter administration time. Conclusion: The VR-EAL appears as an effective neuropsychological tool for the assessment of everyday cognitive functions, which has enhanced ecological validity, a highly pleasant testing experience, and does not induce cybersickness
Transformation of in-plane in at fixed oxygen content
This paper reveals the origin of variation in the magnitude and temperature
dependence of the normal state resistivity frequently observed in different
YBCO single crystal or thin film samples with the same . We investigated
temperature dependence of resistivity in thin films
with 7- and 6.90, which were subjected to annealing in argon at
400-420 K (). Before annealing these films exhibited a non-linear
, with a flattening below 230 K, similar to and
observed in untwinned and twinned YBCO crystals, respectively.
For all films the annealing causes an increase of resistivity and a
transformation of from a non-linear dependence towards a more
linear one (less flattening). In films with 7- the increase of
resistivity is also associated with an increase in . We proposed the
model that provides an explanation of these phenomena in terms of thermally
activated redistribution of residual O(5) oxygens in the chain-layer of YBCO.
Good agreement between the experimental data for , where t is
the annealing time, and numerical calculations was obtained.Comment: 8 pages, 9 figures, submitted to PR
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