Two complementary molecular energy decomposition schemes: the Mayer and Ziegler-Rauk methods in comparison

In the present paper we discuss and compare two different energy decomposition schemes: Mayer's Hartree-Fock energy decomposition into diatomic and monoatomic contributions [Chem. Phys. Lett. 382, 265 (2003)], and the Ziegler-Rauk dissociation energy decomposition [Inorg. Chem. 18, 1558 (1979)]. The Ziegler-Rauk scheme is based on a separation of a molecule into fragments, while Mayer's scheme can be used in the cases where a fragmentation of the system in clearly separable parts is not possible. In the Mayer scheme, the density of a free atom is deformed to give the one-atom Mulliken density that subsequently interacts to give rise to the diatomic interaction energy. We give a detailed analysis of the diatomic energy contributions in the Mayer scheme and a close look onto the one-atom Mulliken densities. The Mulliken density ρA has a single large maximum around the nuclear position of the atom A, but exhibits slightly negative values in the vicinity of neighboring atoms. The main connecting point between both analysis schemes is the electrostatic energy. Both decomposition schemes utilize the same electrostatic energy expression, but differ in how fragment densities are defined. In the Mayer scheme, the electrostatic component originates from the interaction of the Mulliken densities, while in the Ziegler-Rauk scheme, the undisturbed fragment densities interact. The values of the electrostatic energy resulting from the two schemes differ significantly but typically have the same order of magnitude. Both methods are useful and complementary since Mayer's decomposition focuses on the energy of the finally formed molecule, whereas the Ziegler-Rauk scheme describes the bond formation starting from undeformed fragment densities

One- and two-center physical space partitioning of the energy in the density functional theory

A conceptually new approach is introduced for the decomposition of the molecular energy calculated at the density functional theory level of theory into sum of one- and two-atomic energy components, and is realized in the "fuzzy atoms" framework. (Fuzzy atoms mean that the three-dimensional physical space is divided into atomic regions having no sharp boundaries but exhibiting a continuous transition from one to another.) The new scheme uses the new concept of "bond order density" to calculate the diatomic exchange energy components and gives them unexpectedly close to the values calculated by the exact (Hartree-Fock) exchange for the same Kohn-Sham orbitals

Stress e coping no período perioperatório de câncer de mama

Este trabalho é uma revisão bibliográfica, que objetiva refletir sobre stress e coping no perioperatório de câncer de mama, realizada em bases de dados on-line nacionais, abrangendo trabalhos publicados de 1996 a 2006. Foram encontrados 63 artigos, sendo selecionados 17, que foram lidos, analisados e agrupados em categorias temáticas: 1) O câncer de mama como estressor e o impacto do diagnóstico; 2) Stress e o tratamento do câncer de mama; 3) Coping e o câncer de mama, e 4) O enfermeiro como colaborador do processo de enfrentamento. Esse trabalho permitiu identificar que é vasta a literatura nacional sobre câncer de mama, mas poucos são os trabalhos que enfatizam stress e câncer de mama como processo vivenciado pela paciente. Por isso, pode dar direção a pesquisas futuras acerca dos estressores vivenciados pela mulher com câncer de mama no Brasil, e quais as estratégias de coping que ela utiliza para enfrentá-los.

A bi-dimensional genome scan for prolificacy traits in pigs shows the existence of multiple epistatic QTL

Background: Prolificacy is the most important trait influencing the reproductive efficiency of pig production systems. The low heritability and sex-limited expression of prolificacy have hindered to some extent the improvement of this trait through artificial selection. Moreover, the relative contributions of additive, dominant and epistatic QTL to the genetic variance of pig prolificacy remain to be defined. In this work, we have undertaken this issue by performing one-dimensional and bi-dimensional genome scans for number of piglets born alive (NBA) and total number of piglets born (TNB) in a three generation Iberian by Meishan F2 intercross. Results: The one-dimensional genome scan for NBA and TNB revealed the existence of two genome-wide highly significant QTL located on SSC13 (P < 0.001) and SSC17 (P < 0.01) with effects on both traits. This relative paucity of significant results contrasted very strongly with the wide array of highly significant epistatic QTL that emerged in the bi-dimensional genome-wide scan analysis. As much as 18 epistatic QTL were found for NBA (four at P < 0.01 and five at P < 0.05) and TNB (three at P < 0.01 and six at P < 0.05), respectively. These epistatic QTL were distributed in multiple genomic regions, which covered 13 of the 18 pig autosomes, and they had small individual effects that ranged between 3 to 4% of the phenotypic variance. Different patterns of interactions (a × a, a × d, d × a and d × d) were found amongst the epistatic QTL pairs identified in the current work.Conclusions: The complex inheritance of prolificacy traits in pigs has been evidenced by identifying multiple additive (SSC13 and SSC17), dominant and epistatic QTL in an Iberian × Meishan F2 intercross. Our results demonstrate that a significant fraction of the phenotypic variance of swine prolificacy traits can be attributed to first-order gene-by-gene interactions emphasizing that the phenotypic effects of alleles might be strongly modulated by the genetic background where they segregate.

Patient-specific computational hemodynamics of intracranial aneurysms from 3D rotational angiography and CT angiography: an in vivo reproducibility study

Patient-specific simulations of the hemodynamics in intracranial aneurysms can be constructed by using image-based vascular models and CFD techniques. This work evaluates the impact of the choice of imaging technique on these simulations

MGMT promoter methylation in malignant gliomas.

The O(6)-methylguanine-DNA methyltransferase (MGMT) gene is located at chromosome 10q26 and codes for a DNA repair enzyme that--if active--can counteract the effects of alkylating chemotherapy. Malignant gliomas often have the MGMT gene inactivated due to aberrant methylation of its promoter region. The assessment of the MGMT promoter methylation status has become of clinical relevance as a molecular marker associated with response to alkylating chemotherapy and prolonged survival of glioblastoma patients. MGMT promoter methylation testing is also on the merge of being used as a marker for patient selection within clinical trials, e.g., the current CENTRIC trial that is specifically focusing on patients with MGMT promoter-methylated glioblastomas. In anaplastic gliomas, MGMT promoter methylation is a favorable prognostic marker independent of the type of therapy, i.e., radio- or chemotherapy. This occurrence might be associated with the high incidence of other prognostically favorable molecular markers in these tumors, such as IDH1 mutation, 1p/19q deletion or yet to be identified novel aberrations. A variety of different methods are being used to assess MGMT promoter methylation in clinical samples, which may give rise to inter-laboratory variations in test results. Immunohistochemical determination of MGMT protein expression has not proven reliable for diagnostic purposes. This brief review article aims to summarize the main aspects of MGMT promoter methylation testing in contemporary neuro-oncology, in particular its value as a clinically useful molecular marker, putting it into the context of other molecular markers of clinical use in gliomas of adult patients.

Estresse, coping e estado de saúde entre enfermeiros hospitalares

Estudo quantitativo com o objetivo de identificar estressores, nível de estresse dos enfermeiros, estado geral de saúde e formas de enfrentamento utilizadas pelos enfermeiros no ambiente de trabalho. Os dados foram coletados utilizando-se três instrumentos: formulário para levantamento de atividades diárias; inventário de estratégias de coping; inventário sobre o estado geral de saúde. A população deste estudo foi composta de 143 enfermeiros e a maioria encontra-se com baixo nível de estresse (55,25%) e com estado regular de saúde (50,35%). Em relação às formas de enfrentamento, identificou-se resolução de problemas como o fator de maior média. Concluindo, ações educativas devem ser incentivadas, a fim de disponibilizar ferramentas para que o profissional desenvolva estratégias de coping resolutivas em seu dia a dia, minimizando o efeito do estresse no seu estado de saúde e no seu trabalho.

Diseño, implementación y evaluación de un juego educativo basado en puzles con scaffolding enfocado a las redes de ordenadores

En los últimos años, el sector de las TIC (Tecnologías de la Información y la Comunicación) está contemplando cómo va creciendo la demanda de profesionales y, a la vez, el número de matriculaciones universitarias está cayendo. Esta situación está comenzando a ser alarmante dentrodel mundo de las empresas y profesionales de este campo.Con el fin de buscar una solución, se ha demostrado que existen una serie de metodologías pedagógicas basadas en la teoría Constructivista que, combinadas con la tecnología software necesaria, pueden incrementar el nivel de interés de los estudiantes por el mundo de las TIC. Apesar de ello, actualmente hay una escasez de herramientas que implementen dichas metodologías pedagógicas y que proporcionen al mismo tiempo los mecanismos necesarios para dar apoyo a los estudiantes durante el aprendizaje de conceptos TIC. Una posible solución a este problema es la creación de juegos educativos que implementen este tipo de metodologías y que integren mecanismos de scaffolding, es decir, mecanismos de apoyo al aprendizaje del estudiante.Dentro de este marco, siguiendo la propuesta de un modelo conceptual que define los elementos necesarios para crear juegos basados en puzles con scaffolding, el propósito que tiene este proyectoes dar a conocer conceptos relacionados con las TIC mediante la implementación de un juego educativo con la intención de despertar el interés de los estudiantes por esta área. En concreto, el proyecto se basa en el diseño, implementación y evaluación de un juego educativo dentro del área de las redes de ordenadores que proporcione mecanismos de ayuda a los estudiantes para guiarlos a que alcancen soluciones correctas.