Evaluation of permethrin in rats brains

Pyrethrins and pyrethroids interfere with the functions of the nervous system. Exposure to very high levels of these substances can cause dizziness, headaches, nausea, muscle spasms, weakness, loss of consciousness and convulsions. There is no evidence that pyrethrins and pyrethroids can affect the reproductive capacity of human beings but some studies have shown reduced fertility in animals. The Occupational Safety and Health Administration (OSHA) has established in 5 milligrams of pyrethrins per cubic meter of air over 40 hours of weekly work, the concentration limit of this substance in the workplace. From this study, it is possible to conclude that is possible to use a methodology to quantify permethrin residues in rats’ brains. It was proved that permethrin can remain in brain during long time. 50% of the rats have permethrin after 24h. The exposition with alkaline water increases the levels of permethrin in brain. By other side, vitamin E, may act as a protecting factor decreasing the levels until not detected

Experimental and numerical study of methods to displace oil and water in complex pipe geometries for subsea engineering

The purpose of the thesis is to study fluid displacement operations in complex pipe geometries utilized in offshore petroleum industry. Typically, MEG or Methanol is circulated through specific sections of the subsea production systems to lower the hydrocarbon content. This is often done at the beginning of production after a prolonged production shut-in, to avoid formation of hydrates or to minimize the emissions of chemicals to the environment. Experimental and numerical analyses have been conducted modifying a previously built pipe system formed a U-shaped jumper, adding a fluid recirculation line, a jet pump, a centrifugal pump, some new valves and sensors. During the experiments the volume fraction in the U-shaped jumper of the displacing fluid was estimated versus time by measuring the level of the oil-water interface in each pipe segment. The system was filled and displaced with both distilled water with 3% water content of salt and Exxsol D60. Numerical simulations were performed using the one-dimensional transient multi-phase flow simulator LedaFlow. It has been investigated the necessary displacing time required to achieve target hydrocarbon concentration in the domain, optimal displacement rate for efficiently removal of hydrocarbons, and how these variables depend on two different fluids (oil and water) and their properties. The displacement has been also modelled including or removing the recirculation line. After carrying out the simulations and performing the experiments, the results were compared, also against a new simplified mathematical model based on uniform mixing in a tank with the same volume as the pipe geometry. The results show that there is a fair agreement between the experimental results, and the results of the simplified model and the LedaFlow simulations. When including the recirculation line it took longer time to reach the target volume fraction, but the displacing rate can be lower than when the recirculation line is not present

The effect of differential quality and differential zealotry in the best-of-n problem

© 2020 Owner/Author. In this paper, we study the interplay between differential option quality and differential quantity of individuals with fixed option (henceforth called zealots), in a best-of-n problem with n - 2 options. We study how the consensus equilibria change with respect to these two factors. We perform systematic computer simulations in an antagonistic scenario whereby one option has a higher quality but a minority of zealots compared to the other option

Fourier-Hermite decomposition of the collisional Vlasov-Maxwell system: implications for the velocity space cascade

Turbulence at kinetic scales is an unresolved and ubiquitous phenomenon that characterizes both space and laboratory plasmas. Recently, new theories, {\it in-situ} spacecraft observations and numerical simulations suggest a novel scenario for turbulence, characterized by a so-called phase space cascade -- the formation of fine structures, both in physical and velocity space. This new concept is here extended by directly taking into account the role of inter-particle collisions, modeled through the nonlinear Landau operator or the simplified Dougherty operator. The characteristic times, associated with inter-particle correlations, are derived in the above cases. The implications of introducing collisions on the phase space cascade are finally discussed.Comment: Special issue featuring the invited talks from the International Congress on Plasma Physics (ICPP) in Vancouver, Canada 4-8 June 201

Exact hybrid-kinetic equilibria for magnetized plasmas with shearing flows

Context. Magnetized plasmas characterized by shearing flows are present in many natural contexts, such as the Earth's magnetopause and the solar wind. The collisionless nature of involved plasmas requires a kinetic description. When the width of the shear layer is of the order of ion scales, the Hybrid Vlasov-Maxwell approach can be adopted. Aims. The aim of the paper is to derive explicit forms for stationary configurations of magnetized plasmas with planar shearing flows,within the Hybrid Vlasov-Maxwell description. Two configurations are considered: the first with a uniform magnetic field obliquely directed with respect to the bulk velocity; and the second with a uniform-magnitude variable-direction magnetic field. Methods. Stationary ion distribution functions are obtained by combining single-particle constant of motions, which are derived studying particle dynamics. Preliminary information about the form of the distribution functions are analytically derived considering a local approximation for the background electromagnetic field. Then, a numerical method is set up to obtain a solution for general profiles. Results. The explicit distribution functions that are found allow to obtain profiles of density, bulk velocity, temperature and heat flux. Anisotropy and agyrotropy in the distribution function are also evaluated. Stationarity of the solution during numerical simulations is checked in the uniform oblique magnetic field case. Conclusions. The considered configurations can be used as models for the Earth's magnetopause in simulations of the Kelvin-Helmholtz instability.Comment: 13 pages, 12 figure

Separation of heat and charge currents for boosted thermoelectric conversion

In a multi-terminal device the (electronic) heat and charge currents can follow different paths. In this paper we introduce and analyse a class of multi-terminal devices where this property is pushed to its extreme limits, with charge $and$ heat currents flowing in different reservoirs. After introducing the main characteristics of such $heat-charge$ $current$ $separation$ regime we show how to realise it in a multi-terminal device with normal and superconducting leads. We demonstrate that this regime allows to control independently heat and charge flows and to greatly enhance thermoelectric performances at low temperatures. We analyse in details a three-terminal setup involving a superconducting lead, a normal lead and a voltage probe. For a generic scattering region we show that in the regime of heat-charge current separation both the power factor and the figure of merit $ZT$ are highly increased with respect to a standard two-terminal system. These results are confirmed for the specific case of a system consisting of three coupled quantum dots.Comment: 12 pages, 8 figure