The Ab-Initio Simulation of the Liquid Ga-Se System

Ab-initio dynamical simulation is used to study the liquid Ga-Se system at the three concentrations Ga$_2$Se, GaSe and Ga$_2$Se$_3$ at the temperature 1300~K. The simulations are based on the density functional pseudopotential technique, with the system maintained on the Born-Oppenheimer surface by conjugate gradients minimization. We present results for the partial structure factors and radial distribution functions, which reveal how the liquid structure depends on the composition. Our calculations of the electrical conductivity $\sigma$ using the Kubo-Greenwood approximation show that $\sigma$ depends very strongly on the composition. We show how this variation of $\sigma$ is related to the calculated electronic density of states. Comparisons with recent experimental determinations of the structure and conductivity are also presented.Comment: REVTEX, 8 pages, 4 uuencoded poscript figures, ([email protected]

Ab-initio simulation of high-temperature liquid selenium

Ab initio molecular dynamics simulation is used to investigate the structure and dynamics of liquid Se at temperatures of 870 and 1370~K. The calculated static structure factor is in excellent agreement with experimental data. The calculated radial distribution function gives a mean coordination number close to 2, but we find a significant fraction of one-fold and three-fold atoms, particularly at 1370~K, so that the chain structure is considerably disrupted. The self-diffusion coefficient has values ($\sim 1 \times 10^{-8}$~m~s$^{-1}$) typical of liquid metals.Comment: 10 pages, 4 Poscript figures, uses REVTE

Plane waves in noncommutative fluids

We study the dynamics of the noncommutative fuid in the Snyder space perturbatively at the first order in powers of the noncommutative parameter. The linearized noncommutative fluid dynamics is described by a system of coupled linear partial differential equations in which the variables are the fluid density and the fluid potentials. We show that these equations admit a set of solutions that are monocromatic plane waves for the fluid density and two of the potentials and a linear function for the third potential. The energy-momentum tensor of the plane waves is calculated.Comment: 11 pages. Version published as a Lette

Fluidos em Espaços Não-Comutativos.

Neste trabalho apresentaremos os resultados da nossa pesquisa sobre a generalização dos fluidos relativísticos na parametrização de Kähler para espaços não-comutativos aplicando métodos de teoria de campo. A nossa proposta se aplica a uma grande classe de fluidos parame-trizados por duas funções arbitrárias suaves: a primeira que generaliza o potencial de Kähler de-nido na superfície dos potenciais complexos do fluido e a segunda que parametriza a equação de estado. Determinamos, também, os vínculos que os graus de liberdade dos fluidos devem satisfazer para que a teoria tenha as simetrias funda-mentais da geometria não-comutativa e calcularemos as grandezas físicas do fluido não-comutativo

Opinions on the use of technology to improve tablet taking in >65-year-old patients on cardiovascular medications.

Objective This study was performed to evaluate the perceptions of the use of technology to improve cardiovascular medicine taking among patients aged >65 years. Methods This qualitative study used focus groups with people aged >65 years taking cardiovascular medications from two East London community centres. Thematic analysis was informed by the Perceptions and Practicalities Approach framework. Results Participants welcomed technologies they considered familiar, accessible, and easy to use. They valued the opportunity to receive alerts to help with forgetting and monitoring their treatment. More advanced technologies such as ingestible sensor systems were considered helpful for elderly people with significant cognitive impairments still living in the community because of improved monitoring by caregivers and clinicians and prolonging independence. Although generally adapting to the increase in technology in everyday life, participants raised a number of concerns that included potential reduction in face-to-face communication, data security, becoming dependent on technology, and worrying about the consequences of technological failure. Conclusions Participants raised a number of concerns and practical barriers that would need to be addressed for technologies to be accepted and adopted in this patient group