989 resultados para Basis property
Resumo:
Simple electron capture processes are studied using an orthonormal two state continuum-distorted-wave (CDW) basis. The suitability of the basis set is tested by comparing predictions for total and differential cross sections with available experimental data. Overall good agreement is obtained and the authors conclude that a relatively small CDW basis set may be suitable to model a wide variety of low-energy collisions if the members of this extended set are astutely chosen.
Resumo:
In this paper we analyze the representation of the body in blogs by women with breast cancer. Taking into account both texts and images, we study the representation of the body on the basis of the body problems proposed by Frank (1995): control, body-relatedness, other-relatedness and desire. In the blogs studied we find a desiring and dyadic body, which is understood as part of a network of affection and care. The diagnosis of cancer can generate both dissociation, when the body is experienced as a threat, and association, a wish to be connected to it. In relation to control, a clear will of predictability is observed but traces of assumption of contingency also appear.
Resumo:
An overview of a many-body approach to calculation of electronic transport in molecular systems is given. The physics required to describe electronic transport through a molecule at the many-body level, without relying on commonly made assumptions such as the Landauer formalism or linear response theory, is discussed. Physically, our method relies on the incorporation of scattering boundary conditions into a many-body wavefunction and application of the maximum entropy principle to the transport region. Mathematically, this simple physical model translates into a constrained nonlinear optimization problem. A strategy for solving the constrained optimization problem is given. (C) 2004 Wiley Periodicals, Inc.
Resumo:
An efficient method for calculating the electronic structure of systems that need a very fine sampling of the Brillouin zone is presented. The method is based on the variational optimization of a single (i.e., common to all points in the Brillouin zone) basis set for the expansion of the electronic orbitals. Considerations from k.p-approximation theory help to understand the efficiency of the method. The accuracy and the convergence properties of the method as a function of the optimal basis set size are analyzed for a test calculation on a 16-atom Na supercell.
Resumo:
Metal nanoclusters can be produced cheaply and precisely in an electrochemical environment. Experimentally this method works in some systems, but not in others, and the unusual stability of the clusters has remained a mystery. We have simulated the deposition of the clusters using classical molecular dynamics and studied their stability by grand-canonical Monte Carlo simulations. We find that electrochemically stable clusters occur only in those cases where the two metals involved form stable alloys.
Resumo:
La Contratación Pública constituye una fuente muy importante de la demanda de bienes y servicios, especialmente en la Comunidad Autónoma del País Vasco en donde el Gobierno Autonómico, también llamado la Administración General Vasca, desarrolla un papel capital como impulsor de dicha contratación pública. Por otro lado, la Economía Social, y especialmente el movimiento cooperativo, tiene en ese mismo ámbito geográfico un papel de gran peso en el conjunto de la Economía Vasca, por sus cifras de empleo y aportación al PIB, así como por tradición y arraigo social. Cabe preguntarse en tal caso, cuál es el papel que desempeñan las cooperativas en la Contratación Pública en aquella Comunidad Autónoma, cómo y cuáles son los contratos de los que resultan adjudicatarias, qué importes suponen esos contratos para las cuentas públicas y, en definitiva, si su papel de adjudicatarias se corresponde con el que desempeñan en el conjunto de la Economía Vasca. Del examen de los contratos publicados en el Perfil del Contratante del Gobierno Vasco, se obtienen datos suficientes que, una vez procesados y analizados, se visualizan en tablas y porcentajes que constituyen la base de un diagnóstico que responde a las preguntas planteadas y evidencia la situación de debilidad de las cooperativas en el campo de la contratación pública vasca.
Resumo:
Among the duties of the government bodies’ members of the different entities, which are connected to the good government, the duty of loyalty must be underlined. This duty, derived from the good-faith duty, obliges to act in the interest of the entity in case of conflict of interest, and to subordinate one’s own interests, except when there is an authorisation. Loyalty duty is applicable both to managers, who must manage the entity’s interest, and to partners, according to the common purpose derived from the company contract. This duty, at the same time, includes some particular rules, referred to transparency, remuneration, prohibition of competition, self-contracting... This essay compares the regulation of the duty of loyalty and its realizations in the different Cooperative Laws in Spain, both referring to the managers and to the partners, comparing this, at the same time, with the regulation of these aspects in companies’ general legislation, an in the Spanish Corporate Enterprises Act in particular, in order to obtain a general view of the issue, a necessary basis to go more deeply into it, and suggesting some preliminary conclusions or assessments.
Resumo:
A generic architecture for implementing the advanced encryption standard (AES) encryption algorithm in silicon is proposed. This allows the instantiation of a wide range of chip specifications, with these taking the form of semiconductor intellectual property (IP) cores. Cores implemented from this architecture can perform both encryption and decryption and support four modes of operation: (i) electronic codebook mode; (ii) output feedback mode; (iii) cipher block chaining mode; and (iv) ciphertext feedback mode. Chip designs can also be generated to cover all three AES key lengths, namely 128 bits, 192 bits and 256 bits. On-the-fly generation of the round keys required during decryption is also possible. The general, flexible and multi-functional nature of the approach described contrasts with previous designs which, to date, have been focused on specific implementations. The presented ideas are demonstrated by implementation in FPGA technology. However, the architecture and IP cores derived from this are easily migratable to other silicon technologies including ASIC and PLD and are capable of covering a wide range of modem communication systems cryptographic requirements. Moreover, the designs produced have a gate count and throughput comparable with or better than the previous one-off solutions.
Resumo:
Subfertility in men is a heterogeneous syndrome, its pathophysiology remaining unknown in the majority of affected men. A large number of genes and loci are associated with sterility in experimental animals, but the human homologues of most of these genes have not been characterized. A British study suggested that, in a large proportion of men with idiopathic infertility, the disorder is inherited as an autosomal recessive trait; this provocative hypothesis needs confirmation. Because normal germ cell development requires the temporally and spatially co-ordinated expression of a number of gene products at the hypothalamic, pituitary and testicular levels, it is safe to predict that a large number of autosomal, as well as X- and Y-linked, genes will probably be implicated in different subsets of male subfertility.
Resumo:
Density functional calculations, using B3LPY/6-31G(d) methods, have been used to investigate the conformations and vibrational (Raman) spectra of three short-chain fatty acid methyl esters (FAMEs) with the formula CnH2nO2 (n = 3-5). In all three FAMEs, the lowest energy conformer has a simple 'all-trans' structure but there are other conformers, with different torsions about the backbone, which lie reasonably close in energy to the global minimum. One result of this is that the solid samples we studied do not appear to consist entirely of the lowest energy conformer. Indeed, to account for the 'extra' bands that were observed in the Raman data but were not predicted for the all-trans conformer, it was necessary to add-in contributions from other conformers before a complete set of vibrational assignments could be made. Provided this was done, the agreement between experimental Raman frequencies and 6-31G(d) values (after scaling) was excellent, RSD = 12.6 cm(-1). However, the agreement between predicted and observed intensities was much less satisfactory. To confirm the validity of the approach followed by the 6-3 1 G(d) basis set, we used a larger basis set, Sadlej pVTZ, and found that these calculations gave accurate Raman intensities and simulated spectra (summed from two different conformers) that were in quantitative agreement with experiment. In addition, the unscaled Sadlej pVTZ, and the scaled 6-3 1 G(d) calculations gave the same vibrational mode assignments for all bands in the experimental data. This work provides the foundation for calculations on longer-chain FAMEs (which are closer to those found as triglycerides in edible fats and oils) because it shows that scaled 6-3 1 G(d) calculations give equally accurate frequency predictions, and the same vibrational mode assignments, as the much more CPU-expensive Sadlej pVTZ basis set calculations.