Inelastic lifetimes of hot electrons in real metals

We report a first-principles description of inelastic lifetimes of excited electrons in real Cu and Al, which we compute, within the GW approximation of many-body theory, from the knowledge of the self-energy of the excited quasiparticle. Our full band-structure calculations indicate that actual lifetimes are the result of a delicate balance between localization, density of states, screening, and Fermi-surface topology. A major contribution from $d$-electrons participating in the screening of electron-electron interactions yields lifetimes of excited electrons in copper that are larger than those of electrons in a free-electron gas with the electron density equal to that of valence ($4s^1$) electrons. In aluminum, a simple metal with no $d$-bands, splitting of the band structure over the Fermi level results in electron lifetimes that are smaller than those of electrons in a free-electron gas.Comment: 4 papes, 2 figures, to appear in Phys. Rev. Let

Non-equilibrium concentration fluctuations in binary liquids with realistic boundary conditions

Because of the spatially long-ranged nature of spontaneous fluctuations in thermal non-equilibrium systems, they are affected by boundary conditions for the fluctuating hydrodynamic variables. In this paper we consider a liquid mixture between two rigid and impervious plates with a stationary concentration gradient resulting from a temperature gradient through the Soret effect. For liquid mixtures with a large Lewis number, we are able to obtain explicit analytical expressions for the intensity of the non-equilibrium concentration fluctuations as a function of the frequency $\omega$ and the wave number $q$ of the fluctuations. In addition we elucidate the spatial dependence of the intensity of the non-equilibrium fluctuations responsible for a non-equilibrium Casimir effect.Comment: 9 pages, 2 figure

Study of Composite Materials using Zigzag Theory on Timoshenko Beams

This final studies work target is to contribute two new beam theories to MAT-fem [6], an educational developed program by CIMNE [5]. Until now the MAT-fem Beams program only offered the Euler-Bernoulli and Timoshenko beam theories for homogeneous materials. With this work, the Timoshenko theory for composite materials and the refined zigzag theory are added. MAT-fem Beams application works by discretizing beams into two noded elements. This work offers a beam theories opportunity of contrasting with up to four kinematic variables. Timoshenko theory for composite materials works with three kinematics variables per node and zigzag theory works with four variables. Finally, the accuracy of zigzag theory must be remarked in comparison to other classic beam theories

The Stokes-Einstein Relation at Moderate Schmidt Number

The Stokes-Einstein relation for the self-diffusion coefficient of a spherical particle suspended in an incompressible fluid is an asymptotic result in the limit of large Schmidt number, that is, when momentum diffuses much faster than the particle. When the Schmidt number is moderate, which happens in most particle methods for hydrodynamics, deviations from the Stokes-Einstein prediction are expected. We study these corrections computationally using a recently-developed minimally-resolved method for coupling particles to an incompressible fluctuating fluid in both two and three dimensions. We find that for moderate Schmidt numbers the diffusion coefficient is reduced relative to the Stokes-Einstein prediction by an amount inversely proportional to the Schmidt number in both two and three dimensions. We find, however, that the Einstein formula is obeyed at all Schmidt numbers, consistent with linear response theory. The numerical data is in good agreement with an approximate self-consistent theory, which can be used to estimate finite-Schmidt number corrections in a variety of methods. Our results indicate that the corrections to the Stokes-Einstein formula come primarily from the fact that the particle itself diffuses together with the momentum. Our study separates effects coming from corrections to no-slip hydrodynamics from those of finite separation of time scales, allowing for a better understanding of widely observed deviations from the Stokes-Einstein prediction in particle methods such as molecular dynamics.Comment: Submitte

Violation of action--reaction and self-forces induced by nonequilibrium fluctuations

We show that the extension of Casimir-like forces to fluctuating fluids driven out of equilibrium can exhibit two interrelated phenomena forbidden at equilibrium: self-forces can be induced on single asymmetric objects and the action--reaction principle between two objects can be violated. These effects originate in asymmetric restrictions imposed by the objects' boundaries on the fluid's fluctuations. They are not ruled out by the second law of thermodynamics since the fluid is in a nonequilibrium state. Considering a simple reaction--diffusion model for the fluid, we explicitly calculate the self-force induced on a deformed circle. We also show that the action--reaction principle does not apply for the internal Casimir forces exerting between a circle and a plate. Their sum, instead of vanishing, provides the self-force on the circle-plate assembly.Comment: 4 pages, 1 figure. V2: New title; Abstract partially rewritten; Largely enhanced introductory and concluding remarks (incl. new Refs.

Perfil Inmunohistoquímico de los Tipos de Fibras en el Músculo Vocal Humano

Galdames, IS (reprint author), Univ Talca, Escuela Fonoaudiol, Ave Lircay S-N,Oficina 104, Talca, Chile.he vocal muscle is a striated muscle with important functions in the emission of laryngeal sound and physiology of the voice. Therefore the knowledge of its constitution is the basis for the prevention and management of voice disorders. We used 10 samples from the middle third of vocal muscles obtained from autopsies of 6 male and 4 female subjects aged between 36 and 71 years. The samples were analyzed with BA-F8 monoclonal antibody to slow type I fibers, and antimyosin HC monoclonal antibody and antimyosin fast clone MY-32 antibody for types IIA, IIB, IIX, and neonatal fibers. We determined the distribution of the muscle fiber types and morphometric characteristics, evaluating the differences by sex and age group. The human vocal muscle presented a heterogeneous formation with a predominance of type II fibers at 51.99%, while type I fibers reached 48.01%; this difference was significant (p0.05). In conclusion, the human vocal muscle the fibers were predominantly type II fast

Risk genes in head and neck cancer: a systematic review and meta-analysis of last 5 years

Head and Neck Carcinoma (HNC), of which the majority are squamous cell carcinomas of the head and neck (SCCHN), is the sixth most prevalent cancers in mankind and, presents high morbidity and low rates of survival.1 It is known that the apoptotic and proliferation genes are involved in cancer development and these could be useful as a biomarker of this pathology. Systematic reviews and meta-analysis allow stronger and more generalized conclusions for identifying some models of risk markers. These models may help in screening, early diagnosis and/or therapy in the clinic.2-5 In recent decades, there has been increased interest in genetic predisposition studies in complex disease. This has led to the production of an enormous number of epidemiologic papers about the relationship between genetic polymorphism and disease. However, the magnitude of association between specific polymorphism and disease is still not established. The identification of a predictive model of risk polymorphisms could help in early diagnosis, and in understanding disease recurrence and/or progression in the subset of patientssubmittedVersio

Lattice Boltzmann - Langevin simulations of binary mixtures

We report a hybrid numerical method for the solution of the model H fluctuating hydrodynamic equations for binary mixtures. The momentum conservation equations with Landau-Lifshitz stresses are solved using the fluctuating lattice Boltzmann equation while the order parameter conservation equation with Langevin fluxes are solved using the stochastic method of lines. Two methods, based on finite difference and finite volume, are proposed for spatial discretisation of the order parameter equation. Special care is taken to ensure that the fluctuation-dissipation theorem is maintained at the lattice level in both cases. The methods are benchmarked by comparing static and dynamic correlations and excellent agreement is found between analytical and numerical results. The Galilean invariance of the model is tested and found to be satisfactory. Thermally induced capillary fluctuations of the interface are captured accurately, indicating that the model can be used to study nonlinear fluctuations

Sustainability, Efficiency and Equitability of Water Consumption and Pollution in Latin America and the Caribbean

This paper assesses the sustainability, efficiency and equity of water use in Latin America and the Caribbean (LAC) by means of a geographic Water Footprint Assessment (WFA). It aims to provide understanding of water use from both a production and consumption point of view. The study identifies priority basins and areas from the perspectives of blue water scarcity, water pollution and deforestation. Wheat, fodder crops and sugarcane are identified as priority products related to blue water scarcity. The domestic sector is the priority sector regarding water pollution from nitrogen. Soybean and pasture are priority products related to deforestation. We estimate that consumptive water use in crop production could be reduced by 37% and nitrogen-related water pollution by 44% if water footprints were reduced to certain specified benchmark levels. The average WF per consumer in the region is 28% larger than the global average and varies greatly, from 912 m3/year per capita in Nicaragua to 3468 m3/year in Bolivia. Ironically, the LAC region shows significant levels of undernourishment, although there is abundant water and food production in the region and substantial use of land and water for producing export crops like soybean