22,260 research outputs found
Dyes removal from water using low cost absorbents
In this study, the removal capacity of low cost adsorbents during the adsorption of Methylene Blue (MB) and Congo Red (CR) at different concentrations (50 and 100mg•L-1) was evaluated. These adsorbents were produced from wood wastes (cedar and teak) by chemical activation (ZnCl2). Both studied materials, Activated Cedar (AC) and activated teak (AT) showed a good fit of their experimental data to the pseudo second order kinetic model and Langmuir isotherms. The maximum adsorption capacities for AC were 2000.0 and 444.4mg•g-1 for MB and CR, respectively, while for AT, maximum adsorption capacities of 1052.6 and 86.4mg•g-1 were found for MB and CR, respectively. © Published under licence by IOP Publishing Ltd
Diamagnetic Interactions in Disordered Suspensions of Metastable Superconducting Granules
The simulation of the transition sequence of superheated Type I
superconducting granules (SSG) in disordered suspensions when an external
magnetic field is slowly increased from zero has been studied. Simulation takes
into account diamagnetic interactions and the presence of surface defects.
Results have been obtained for the transition sequence and surface fields
distribution covering a wide range of densities. These results are compared
with previous analytical perturbative theory, which provides qualitative
information on transitions and surface magnetic fields during transitions, but
with a range of validity apparently limited to extremely dilute samples.
Simulations taking into account the complete diamagnetic interactions between
spheres appear to be a promising tool in interpreting SSG experiments, in
applications such as particle detectors, and in some fundamental calculations
of Solid State Physics.Comment: 25 pages, 11 figures, accepted for publication in European Physics
Journal
Premium Estimation Inaccuracy and the Actuarial Performance of the US Crop Insurance Program
This article explores the impact of the likely levels of inaccuracy associated with two main types of premium estimation methods, under different sample sizes, on the actuarial performance of the US crop insurance program. The analyses are conducted under several plausible assumptions about the insurer versus the producers’ estimates for their actuarially fair premiums. Significant differences are found due to estimation method and sample size, with the currently used procedures resulting in the worse actuarial performance. Several conclusions and recommendations are provided that could markedly reduce the amount of public subsidies needed to keep this program solvent.Agricultural Subsidies, Crop Insurance Premium Estimation, Loss-Cost Procedures, Risk Management Agency, Financial Economics,
Top quark forward-backward asymmetry from the model
The forward-backward asymmetry in top quark pair production,
measured at the Tevatron, is probably related to the contribution of new
particles. The Tevatron result is more than a deviation from the
standard model prediction and motivates the application of alternative models
introducing new states.
However, as the standard model predictions for the total cross section
and invariant mass distribution for this process are in
good agreement with experiments, any alternative model must reproduce these
predictions. These models can be placed into two categories: One introduces the
s-channel exchange of new vector bosons with chiral couplings to the light
quarks and to the top quark and another relies on the t-channel exchange of
particles with large flavor-violating couplings in the quark sector. In this
work we employ a model which introduces both s- and t-channel nonstandard
contributions for the top quark pair production in proton antiproton
collisions. We use the minimal version of the model (3-3-1 model) that predicts the existence of a new neutral gauge
boson, called . This gauge boson has both flavor-changing couplings
to up and top quarks and chiral coupling to the light quarks and to the top
quark. This very peculiar model coupling can correct the for top quark
pair production for two ranges of mass while leading to cross
section and invariant mass distribution quite similar to the standard model
ones. This result reinforces the role of the 3-3-1 model for any new physics
effect.Comment: 12 pages, 4 figures, 2 table
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