Development of complex classical force fields through force matching to ab initio data: Application to a room-temperature ionic liquid

Recent experimental neutron diffraction data and ab initio molecular dynamics simulation of the ionic liquid dimethylimidazolium chloride ([dmim]Cl) have provided a structural description of the system at the molecular level. However, partial radial distribution functions calculated from the latter, when compared to previous classical simulation results, highlight some limitations in the structural description offered by force fieldbased simulations. With the availability of ab initio data it is possible to improve the classical description of [dmim]Cl by using the force matching approach, and the strategy for fitting complex force fields in their original functional form is discussed. A self-consistent optimization method for the generation of classical potentials of general functional form is presented and applied, and a force field that better reproduces the observed first principles forces is obtained. When used in simulation, it predicts structural data which reproduces more faithfully that observed in the ab initio studies. Some possible refinements to the technique, its application, and the general suitability of common potential energy functions used within many ionic liquid force fields are discussed.

Power dissipation in nanoscale conductors: classical, semi-classical and quantum dynamics

Modelling Joule heating is a difficult problem because of the need to introduce correct correlations between the motions of the ions and the electrons. In this paper we analyse three different models of current induced heating (a purely classical model, a fully quantum model and a hybrid model in which the electrons are treated quantum mechanically and the atoms are treated classically). We find that all three models allow for both heating and cooling processes in the presence of a current, and furthermore the purely classical and purely quantum models show remarkable agreement in the limit of high biases. However, the hybrid model in the Ehrenfest approximation tends to suppress heating. Analysis of the equations of motion reveals that this is a consequence of two things: the electrons are being treated as a continuous fluid and the atoms cannot undergo quantum fluctuations. A means for correcting this is suggested.

Measles virus and classical Hodgkin lymphoma: no evidence for a direct association.

A proportion of Hodgkin lymphoma (HL) cases are causally associated with the Epstein-Barr virus (EBV) but the aetiology of the remaining cases remains obscure. Over the last 3 decades several studies have found an association between HL and measles virus (MV) including a recent cohort study describing the detection of MV antigens in Hodgkin and Reed-Sternberg cells, the tumour cells in HL. In the present study we looked at the relationship between history of MV infection and risk of developing HL in a population-based, case/control study of HL. In addition we used immunohistochemistry and RT-PCR to look for direct evidence of MV in HL biopsies. There was no significant difference in the proportion of cases reporting previous measles compared to controls in the entire data set or when young adults were considered separately. Using a robust immunohistochemical assay for MV infection, we failed to find evidence of MV in biopsies from 97 cases of HL and RT-PCR studies similarly gave negative results. This study therefore provides no evidence that MV is directly involved in the development of HL. However, when age at first reported MV infection was investigated, significant differences emerged with children infected before school-age having higher risk, especially of EBV-ve HL, when compared with children infected at older ages; the interpretation of these latter results is unclear.

New results on a classical operator

It is remarkable how the classical Volterra integral operator, which was one of the first operators which attracted mathematicians' attention, is still worth of being studied. In this essentially survey work, by collecting some of the very recent results related to the Volterra operator, we show that there are new (and not so new) concepts that are becoming known only at the present days. Discovering whether the Volterra operator satisfies or not a given operator property leads to new methods and ideas that are useful in the setting of Concrete Operator Theory as well as the one of General Operator Theory. In particular, a wide variety of techniques like summability kernels, theory of entire functions, Gaussian cylindrical measures, approximation theory, Laguerre and Legendre polynomials are needed to analyze different properties of the Volterra operator. We also include a characterization of the commutator of the Volterra operator acting on L-P[0, 1], 1

La evolución de destinos turísticos litorales consolidados. Análisis comparado de Balneario Camnoriú (Brasil) y Benidorm (España)

El objetivo de este trabajo consiste en estudiar la evolución de los destinos turísticos litorales consolidados a partir del análisis comparado entre Balneario Camboriú y Benidorm. Se trata de dos destinos localizados en contextos territoriales y turísticos diferentes, en los que se contrastan de manera empírica los indicadores de evolución de los destinos y se vinculan las dinámicas evolutivas con el modelo territorial-turístico resultante en cada destino. El análisis realizado permite contrastar los postulados de los modelos evolutivos clásicos (Butler, 1980) e incorporar los nuevos planteamientos de la geografía económica evolutiva. La investigación delimita cronológicamente los periodos de desarrollo de ambos destinos para identificar los factores con mayor incidencia en la evolución de los mismos. Una evolución marcada, fundamentalmente, por la ubicación geográfica, la planificación y gestión urbanoturística a diferentes escalas, la dependencia de determinados mercados emisores y la influencia de factores macroeconómicos. Un conjunto de factores interrelacionados que dibujan trayectorias dispares para los destinos analizados.

The Rhetorical Construction of Corporate Logos

This research is set in the context of today’s societies, in which the corporate visual symbology of a business, corporation or institution constitutes an essential way to transmit its corporate image. Traditional discursive procedures can be discovered in the development of these signs. The rhetorical strategies developed by the great classical authors appear in the logo-symbols expressing the corporate values of today’s companies. Thus, rhetoric is emerging once again in the sense it had many centuries ago: A repertory of rules that, paradoxically, standardizes the deviations of language and whose control is synonymous with power. The main objective of this study is to substantiate the rhetorical construction of logos using as a model of analysis the classical process of creating discourse. This involves understanding logos as persuasive discourses addressed to a modern audience. Our findings show that the rhetorical paradigm can be considered as a creative model for the con­struction of an original logo consistent with a company’s image.