Averaged cubature schemes on the real positive semiaxis

Stratified cubature rules are proposed to approximate double integrals defined on the real positive semiaxis. In particular, anti-Gauss cubature formulae are introduced and averaged cubature schemes are developed. Some of their appropriate modifications are also studied. Several numerical experiments are given to testify the performance of all the formulae

Shot noise suppression at room temperature in atomic-scale Au junctions

Shot noise encodes additional information not directly inferable from simple electronic transport measurements. Previous measurements in atomic-scale metal junctions at cryogenic temperatures have shown suppression of the shot noise at particular conductance values. This suppression demonstrates that transport in these structures proceeds via discrete quantum channels. Using a high frequency technique, we simultaneously acquire noise data and conductance histograms in Au junctions at room temperature and ambient conditions. We observe noise suppression at up to three conductance quanta, with possible indications of current-induced local heating and $1/f$ noise in the contact region at high biases. These measurements demonstrate the quantum character of transport at room temperature at the atomic scale. This technique provides an additional tool for studying dissipation and correlations in nanodevices.Comment: 15 pages, 4 figures + supporting information (6 pages, 6 figures

AVERAGED NYSTRÖM INTERPOLANTS FOR BIVARIATE FREDHOLM INTEGRAL EQUATIONS ON THE REAL POSITIVE SEMI-AXES

Nyström interpolants based on suitable anti-Gauss cubature formulae associated with the Laguerre weights are provided for the numerical solution of second-kind Fredholm integral equations defined on the first quadrant in the coordinate plane (0, ∞) × (0, ∞). The case when the right-hand side and the kernel may increase at the origin and/or at infinity is considered. Numerical tests illustrate the good performance of such interpolants

A Variational Procedure for Time-Dependent Processes

A simple variational Lagrangian is proposed for the time development of an arbitrary density matrix, employing the "factorization" of the density. Only the "kinetic energy" appears in the Lagrangian. The formalism applies to pure and mixed state cases, the Navier-Stokes equations of hydrodynamics, transport theory, etc. It recaptures the Least Dissipation Function condition of Rayleigh-Onsager {\bf and in practical applications is flexible}. The variational proposal is tested on a two level system interacting that is subject, in one instance, to an interaction with a single oscillator and, in another, that evolves in a dissipative mode.Comment: 25 pages, 4 figure

A self-consistent quantum master equation approach to molecular transport

We propose a self-consistent generalized quantum master equation (GQME) to describe electron transport through molecular junctions. In a previous study [M.Esposito and M.Galperin. Phys. Rev. B 79, 205303 (2009)], we derived a time-nonlocal GQME to cure the lack of broadening effects in Redfield theory. To do so, the free evolution used in the Born-Markov approximation to close the Redfield equation was replaced by a standard Redfield evolution. In the present paper, we propose a backward Redfield evolution leading to a time-local GQME which allows for a self-consistent procedure of the GQME generator. This approach is approximate but properly reproduces the nonequilibrium steady state density matrix and the currents of an exactly solvable model. The approach is less accurate for higher moments such as the noise.Comment: 9 pages, 4 figure

The number of transmission channels through a single-molecule junction

We calculate transmission eigenvalue distributions for Pt-benzene-Pt and Pt-butadiene-Pt junctions using realistic state-of-the-art many-body techniques. An effective field theory of interacting $\pi$-electrons is used to include screening and van der Waals interactions with the metal electrodes. We find that the number of dominant transmission channels in a molecular junction is equal to the degeneracy of the molecular orbital closest to the metal Fermi level.Comment: 9 pages, 8 figure

Effect of Thermoelectric Cooling in Nanoscale Junctions

We propose a thermoelectric cooling device based on an atomic-sized junction. Using first-principles approaches, we investigate the working conditions and the coefficient of performance (COP) of an atomic-scale electronic refrigerator where the effects of phonon's thermal current and local heating are included. It is observed that the functioning of the thermoelectric nano-refrigerator is restricted to a narrow range of driving voltages. Compared with the bulk thermoelectric system with the overwhelmingly irreversible Joule heating, the 4-Al atomic refrigerator has a higher efficiency than a bulk thermoelectric refrigerator with the same $ZT$ due to suppressed local heating via the quasi-ballistic electron transport and small driving voltages. Quantum nature due to the size minimization offered by atomic-level control of properties facilitates electron cooling beyond the expectation of the conventional thermoelectric device theory.Comment: 8 figure

Effect of Litter Treatment on the Occurrence of Foot Pad Lesions

Pododermatitis (foot pad lesions) is one of the main welfare problems in modern broiler production in countries with developed poultry farming. Factors contributing to the occurrence of these lesions are nutrition, stocking density and material used for litter. There are a number of different procedures that can be applied in order to prevent and reduce the number of lesions with the most pronounced defects. The experiment was conducted on broiler chickens grown in 10 buildings of 240 m2 each. The stocking density was 35 kg/m2. The experiment was set up in five treatments with two replicates. Treatment one (T1) - control with a straw litter, treatment two (T2) - litter treated with microbial preparation Micropan®, treatment three (T3) – litter with addition of lignin, treatment four (T4) – litter with addition of lignin and Micropan® and treatment five (T5) - chopped straw without supplements. At the end of the experiment, on day 42 the intensity of the lesions was scored on the slaughter line. The presence of lesions was scored using scale from 0 (no lesions) to 3 (plantar pads with more than 50% damage). Based on the results of the trial it can be concluded that litter has a significant impact on the presence and the degree of foot pad lesions. The lowest score of foot pad lesions was observed in the treatment T5 (chopped straw). Different treatments of litters may also contribute to the solution of the problem of pododermatitis since the results in all treated groups (T2, T3, T4 and T5) were better when compared to the control

Soil Ammonification Activity in the Conditions of Mineral and Organic Fertilizer Use

Abstract: Two-year investigations (1996)(1997) were carried out to examine the effect of different N rates (N 1 -30 kg/ha, N 2 -60 kg/ha and N 3 -90 kg/ha), standard P and K amounts (75 kg/ha) and organic fertilizers (solid manure-45 t/ha and liquid manure-80 t/ha) on the microbiological activity of the smonitza soil under spring oats. The trial was set up on the Faculty of Agronomy Experimental Field in Cacak in a randomized block design with three replications. The effect of the applied fertilizers on soil microorganisms had been determined twice during the growing season and observed by establishing the number of ammonifiers and the soil proteinase activity using standard microbiological and biochemical methods. The investigations showed that the applied fertilization variants, sampling periods and study years had affected the number of microorganisms and the soil proteinase activity. Mineral fertilizers had caused a reduction in the number of ammonifiers. The N 3 variant had the highest inhibitory effect of all the variants of the mineral fertilizers studied. The inhibitory effect of the fertilizers used was more pronounced in the second sampling period. As opposed to that, the same fertilizers increased the soil proteinase activity, particularly in the first sampling period. Furthermore, the organic fertilizers used caused a reduction in the number of ammonifiers and proteinase activity. The number of ammonifiers was bigger in 1996 and the soil proteinase activity was reported to be higher during 1997

Redox status, DNA and HSA binding study of naturally occurring naphthoquinone derivatives

In the present work we modified the procedure for isolation of naphthoquinones α-methylbutyrylshikon (1), acetylshikonin (2) and β-hydroxyisovalerylshikonin (3) from Onosma visianii Clem. We also investigated possible mechanisms of 1, 2 and 3 as antitumor agents. Accordingly, we estimated concentrations of superoxide anion radical (O2.-), nitrite (NO2 -) and glutathione in HCT-116 and MDA-MB-231 cell lines. Compounds 1 and 3 expressed significant prooxidative activity, while all tested compounds exhibited significant increase in nitrite levels. Also, all examined compounds significantly increased the concentration of oxidized glutathione (GSSG), suggesting significant prooxidative disbalance. The levels of reduced glutathione (GSH) were also elevated as a part of antioxidative cell response. The data indicate that induced oxidative imbalance could be one of the triggers for previously recorded decreased viability of HCT-116 and MDA-MB-231 cells exposed to tested naphthoquinone derivatives. Moreover, we examined interactions mode of compounds 1, 2 and 3 with CT-DNA as one of the crucial targets of many molecules that express cytotoxic activity. The results obtained by UV-visible, fluorescence and molecular docking study revealed that 1, 2 and 3 bound to CT-DNA through minor groove binding. Furthermore, the interactions between HSA and 1, 2 and 3 were examined employing the same methods as for the CT-DNA interaction study. Based on the obtained results, it can be concluded that naphthoquinones 1, 2 and 3 could be effectively transported by human serum albumin. As a conclusion, this study provides further insight of antitumor activity of selected naphthoquinones