535 research outputs found
<i>In Situ</i> Sampling of Relative Dust Devil Particle Loads and Their Vertical Grain Size Distributions
During a field campaign in the Sahara Desert in southern Morocco, spring 2012, we sampled the vertical grain size distribution of two active dust devils that exhibited different dimensions and intensities. With these in situ samples of grains in the vortices, it was possible to derive detailed vertical grain size distributions and measurements of the lifted relative particle load. Measurements of the two dust devils show that the majority of all lifted particles were only lifted within the first meter (~46.5% and ~61% of all particles; ~76.5 wt % and ~89 wt % of the relative particle load). Furthermore, ~69% and ~82% of all lifted sand grains occurred in the first meter of the dust devils, indicating the occurrence of ‘‘sand skirts.’’ Both sampled dust devils were relatively small (~15m and ~4–5m in diameter) compared to dust devils in surrounding regions; nevertheless, measurements show that ~58.5% to 73.5% of all lifted particles were small enough to go into suspension (<31 mm, depending on the used grain size classification). This relatively high amount represents only ~0.05 to 0.15 wt % of the lifted particle load. Larger dust devils probably entrain larger amounts of fine-grained material into the atmosphere, which can have an influence on the climate. Furthermore, our results indicate that the composition of the surface, on which the dust devils evolved, also had an influence on the particle load composition of the dust devil vortices. The internal particle load structure of both sampled dust devils was comparable related to their vertical grain size distribution and relative particle load, although both dust devils differed in their dimensions and intensities. A general trend of decreasing grain sizes with height was also detected
Electron's anomalous magnetic moment effects on electron-hydrogen elastic collisions in the presence of a circularly polarized laser field
The effect of the electron's anomalous magnetic moment on the relativistic
electronic dressing for the process of electron-hydrogen atom elastic
collisions is investigated. We consider a laser field with circular
polarization and various electric field strengths. The Dirac-Volkov states
taking into account this anomaly are used to describe the process in the first
order of perturbation theory. The correlation between the terms coming from
this anomaly and the electric field strength gives rise to new results, namely
the strong dependence of the spinor part of the differential cross section
(DCS) with respect to these terms. A detailed study has been devoted to the non
relativistic regime as well as the moderate relativistic regime. Some aspects
of this dependence as well as the dynamical behavior of the DCS in the
relativistic regime have been addressed.Comment: 1 File Revtex + 14 figures ep
Effect of zeatin on the infection process and expression of MAPK-4 during pathogenesis of Alternaria brassicae in non-host and host Brassica plants
Recent studies have revealed an important role of hormones in plant immunity. Cytokinins are phytohormones that are involved in various regulatory processes including plant defense. Zeatin a cytokinin antagonizes the effect of Alternaria brassicae pathotoxin in cell culture of Brassica juncea. Phytohormones are also the inducers of MAP Kinase signaling pathways which are the important signaling modules in eukaryotic cells. In this paper, an attempt was made to study the exogenous application of zeatin on the disease score, infection behavior of A. brassicae, expression pattern of MAPK-4 in the non host Sinapsis alba, host B. juncea susceptible c.v Varuna, B. juncea moderately tolerant c.v. Divya and transgenic Brassica to confer its role in plant immunity. We observed that high concentration of zeatin led to increased defense responses by delaying the infection process as well as significantly reducing the disease score. Semi-quantitative RT-PCR reveals that zeatin also increases the expression of MAPK-4 at early hours of infection. Our result supports that zeatin up regulates plant immunity via an elevation of MAPK-4 and clearly reflects that it antagonizes the effect of A. brassicae. The crosstalk between zeatin and MAPK signaling pathway may help plants fine-tune defense responses against A. brassicae in the disease Alternaria blight.Keywords: Alternaria blight, Brassica, disease score, MAPK, pathogenesis, infection processAfrican Journal of BiotechnologyVol. 12(17), pp. 2164-217
Relativistic electronic dressing in laser-assisted ionization of atomic hydrogen by electron impact
Within the framework of the coplanar binary geometry where it is justified to
use plane wave solutions for the study of the reaction and in the
presence of a circularly polarized laser field, we introduce as a first step
the DVRPWBA1 (Dirac-Volkov Plane Wave Born Approximation1) where we take into
account only the relativistic dressing of the incident and scattered electrons.
Then, we introduce the DVRPWBA2 (Dirac-Volkov Plane Wave Born Approximation2)
where we take totally into account the relativistic dressing of the incident,
scattered and ejected electrons. We then compare the corresponding triple
differential cross sections for laser-assisted ionization of atomic hydrogen by
electron impact both for the non relativistic and the relativistic regime.Comment: 18 pages, Latex, 7 figure
Thermodynamic Geometry Of Charged Rotating BTZ Black Holes
We study the thermodynamics and the thermodynamic geometries of charged
rotating BTZ (CR-BTZ) black holes in (2+1)-gravity. We investigate the
thermodynamics of these systems within the context of the Weinhold and
Ruppeiner thermodynamic geometries and the recently developed formalism of
geometrothermodynamics (GTD). Considering the behavior of the heat capacity and
the Hawking temperature, we show that Weinhold and Ruppeiner geometries cannot
describe completely the thermodynamics of these black holes and of their
limiting case of vanishing electric charge. In contrast, the Legendre
invariance imposed on the metric in GTD allows one to describe the CR-BTZ black
holes and their limiting cases in a consistent and invariant manner
Association study of two interleukin-1 gene loci with essential hypertension in a Pakistani Pathan population
An association study of IL-1 beta -511C/T and IL-1 RN 86 bp VNTR polymorphisms with essential hypertension was carried out in a sample population of 500 Pakistani Pathan subjects selected randomly, comprising groups of 235 subjects with hypertension and 265 controls. The distribution of both genotypes and alleles was not statistically different in cases and controls. In conclusion, IL-1 beta -511C/T and IL-1 RN 86 bp VNTR do not contribute to the aetiology of essential hypertension in the Pakistani Pathan population investigated here
Surface heterogeneity and inhomogeneous broadening of vibrational line profiles
The surface heterogeneity of amorphous silica (aSiO2) has been probed using coverage dependent temperature programmed desorption (TPD) of a simple probe molecule, carbon monoxide (CO). The resulting distribution of interaction energies is the foundation from which an environmentally broadened vibrational line profile synthesis has been undertaken. These simulations are compared with measured line profiles recorded at 0.1 cm−1 resolution using reflection–absorption infrared spectroscopy (RAIRS). A comparison of such line profile synthesis for CO on amorphous silica and on porous amorphous solid water (p-ASW) is also reported and conclusions are drawn as to the vibrational relaxation and surface dynamics of the CO molecule on the two surfaces
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