1,147 research outputs found

    The significance of sample mass in the analysis of steroid estrogens in sewage sludges and the derivation of partition coefficients in wastewaters

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    Optimization of an analytical method for determination of steroid estrogens, through minimizing sample size, resulted in recoveries >84%, with relative standard deviations <3% and demonstrated the significance of sample size on method performance. Limits of detection were 2.1–5.3 ng/g. Primary sludges had estrogen concentrations of up to one order of magnitude less than those found in biological sludges (up to 994 ng/g). However, partition coefficients were higher in primary sludges (except estriol), with the most hydrophobic compound (ethinylestradiol) exhibiting the highest Kp value, information which may be of value to those involved in modeling removal during wastewater treatment

    Organic film thickness influence on the bias stress instability in Sexithiophene Field Effect Transistors

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    In this paper, the dynamics of bias stress phenomenon in Sexithiophene (T6) Field Effect Transistors (FETs) has been investigated. T6 FETs have been fabricated by vacuum depositing films with thickness from 10 nm to 130 nm on Si/SiO2 substrates. After the T6 film structural analysis by X-Ray diffraction and the FET electrical investigation focused on carrier mobility evaluation, bias stress instability parameters have been estimated and discussed in the context of existing models. By increasing the film thickness, a clear correlation between the stress parameters and the structural properties of the organic layer has been highlighted. Conversely, the mobility values result almost thickness independent

    Supplying new cocoa planting material to farmers: a review of propagation methodologies

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    The review, coordinated by Bioversity International, presents an impartial, evidence-based review of cacao propagation methods, to serve as a basis for the assessment and implementation of strategies for providing farmers with quality planting materials, adapted to current and future needs (cultural, institutional, technical, environmental and financial). It describes the various propagation methods available for the production and supply of large numbers of cacao plants to growers. It is hoped that the result of the efforts of the key authors provides a basis to build on for case-specific recommendations. As the supply of new improved planting material to farmers is at the heart of improving cocoa productivity and modernizing the crop, we hope that the information in the review will make its way into national cocoa plans, and help to make cocoa farming more attractive and more sustainable

    Comprehensive evaluation of the linear stability of Alfvén eigenmodes driven by alpha particles in an ITER baseline scenario

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    The linear stability of Alfvén eigenmodes in the presence of fusion-born alpha particles is thoroughly assessed for two variants of an ITER baseline scenario, which differ significantly in their core and pedestal temperatures. A systematic approach based on CASTOR-K (Borba and Kerner 1999 J. Comput. Phys. 153 101; Nabais et al 2015 Plasma Sci. Technol. 17 89) is used that considers all possible eigenmodes for a given magnetic equilibrium and determines their growth rates due to alpha-particle drive and Landau damping on fuel ions, helium ashes and electrons. It is found that the fastest growing instabilities in the aforementioned ITER scenario are core-localized, low-shear toroidal Alfvén eigenmodes. The largest growth-rates occur in the scenario variant with higher core temperatures, which has the highest alpha-particle density and density gradient, for eigenmodes with toroidal mode numbers . Although these eigenmodes suffer significant radiative damping, which is also evaluated, their growth rates remain larger than those of the most unstable eigenmodes found in the variant of the ITER baseline scenario with lower core temperatures, which have and are not affected by radiative damping

    Bloch Brane

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    We investigate a system described by two real scalar fields coupled with gravity in (4, 1) dimensions in warped spacetime involving one extra dimension. The results show that the parameter which controls the way the two scalar fields interact induces the appearence of thick brane which engenders internal structure, driving the energy density to localize inside the brane in a very specific way.Comment: 13 pages, 6 figures; some misprints corrected, to appear in JHE

    Ferromagnetism without flat bands in thin armchair nanoribbons

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    Describing by a Hubbard type of model a thin armchair graphene ribbon in the armchair hexagon chain limit, one shows in exact terms, that even if the system does not have flat bands at all, at low concentration a mesoscopic sample can have ferromagnetic ground state, being metallic in the same time. The mechanism is connected to a common effect of correlations and confinement.Comment: 37 pages, 12 figures, in press at Eur. Phys. Jour.

    Lorentz-violating effects on topological defects generated by two real scalar fields

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    The influence of a Lorentz-violation on soliton solutions generated by a system of two coupled scalar fields is investigated. Lorentz violation is induced by a fixed tensor coefficient that couples the two fields. The Bogomol'nyi method is applied and first-order differential equations are obtained whose solutions minimize energy and are also solutions of the equations of motion. The analysis of the solutions in phase space shows how the stability is modified with the Lorentz violation. It is shown explicitly that the solutions preserve linear stability despite the presence of Lorentz violation. Considering Lorentz violation as a small perturbation, an analytical method is employed to yield analytical solutions.Comment: (9 pages, 11 figures

    Search for the Rare Decay KL --> pi0 ee

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    The KTeV/E799 experiment at Fermilab has searched for the rare kaon decay KL--> pi0ee. This mode is expected to have a significant CP violating component. The measurement of its branching ratio could support the Standard Model or could indicate the existence of new physics. This letter reports new results from the 1999-2000 data set. One event is observed with an expected background at 0.99 +/- 0.35 events. We set a limit on the branching ratio of 3.5 x 10^(-10) at the 90% confidence level. Combining the results with the dataset taken in 1997 yields the final KTeV result: BR(KL --> pi0 ee) < 2.8 x 10^(-10) at 90% CL.Comment: 4 pages, three figure

    Sensitivity of alpha-particle-driven Alfvén eigenmodes to q-profile variation in ITER scenarios

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    A perturbative hybrid ideal-MHD/drift-kinetic approach to assess the stability of alpha-particle-driven Alfv�n eigenmodes in burning plasmas is used to show that certain foreseen ITER scenarios, namely the MA baseline scenario with very low and broad core magnetic shear, are sensitive to small changes in the background magnetic equilibrium. Slight variations (of the order of ) of the safety-factor value on axis are seen to cause large changes in the growth rate, toroidal mode number, and radial location of the most unstable eigenmodes found. The observed sensitivity is shown to proceed from the very low magnetic shear values attained throughout the plasma core, raising issues about reliable predictions of alpha-particle transport in burning plasmas

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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