146 research outputs found
Self-energy of image states on copper surfaces
We report extensive calculations of the imaginary part of the electron
self-energy in the vicinity of the (100) and (111) surfaces of Cu. The
quasiparticle self-energy is computed by going beyond a free-electron
description of the metal surface, either within the GW approximation of
many-body theory or with inclusion, within the GW approximation, of
short-range exchange-correlation effects. Calculations of the decay rate of the
first three image states on Cu(100) and the first image state on Cu(111) are
also reported, and the impact of both band structure and many-body effects on
the electron relaxation process is discussed.Comment: 8 pages, 5 figures, to appear in Phys. Rev.
The effects of sample position and gas flow pattern on the sintering of a 7xxx aluminum alloy
The effects of sample position and gas flow pattern on the sintering of a 7xxx aluminum alloy Al-7Zn-2.5Mg-1Cu in flowing nitrogen have been investigated both experimentally and numerically. The near-surface pore distribution and sintered density of the samples show a strong dependency on the sample separation distance over the range from 2 mm to 40 mm. The open porosity in each sample increases with increasing separation distance while the closed porosity remains essentially unchanged. A two-dimensional computational fluid dynamics (CFD) model has been developed to analyze the gas flow behavior near the sample surfaces during isothermal sintering. The streamlines, velocity profile, and volume flow rate in the cavity between each two samples are presented as a function of the sample separation distance at a fixed nitrogen flow rate of 6 L/min. The CFD modeling results provide essential details for understanding the near-surface pore distribution and density of the sintered samples. It is proposed that the different gas flow patterns near the sample surfaces result in variations of the oxygen content from the incoming nitrogen flow in the local sintering atmosphere, which affects the self-gettering process of the aluminum compacts during sintering. This leads to the development of different near-surface pore distributions and sintered densities
Computational Identification and Analysis of the Key Biosorbent Characteristics for the Biosorption Process of Reactive Black 5 onto Fungal Biomass
The performances of nine biosorbents derived from dead fungal biomass were investigated for their ability to remove Reactive Black 5 from aqueous solution. The biosorption data for removal of Reactive Black 5 were readily modeled using the Langmuir adsorption isotherm. Kinetic analysis based on both pseudo-second-order and Weber-Morris models indicated intraparticle diffusion was the rate limiting step for biosorption of Reactive Black 5 on to the biosorbents. Sorption capacities of the biosorbents were not correlated with the initial biosorption rates. Sensitivity analysis of the factors affecting biosorption examined by an artificial neural network model showed that pH was the most important parameter, explaining 22%, followed by nitrogen content of biosorbents (16%), initial dye concentration (15%) and carbon content of biosorbents (10%). The biosorption capacities were not proportional to surface areas of the sorbents, but were instead influenced by their chemical element composition. The main functional groups contributing to dye sorption were amine, carboxylic, and alcohol moieties. The data further suggest that differences in carbon and nitrogen contents of biosorbents may be used as a selection index for identifying effective biosorbents from dead fungal biomass
Female Institutional Directors on Boards and Firm Value
The aim of this research is to examine what impact female institutional directors on boards have on corporate performance. Previous research shows that institutional female directors cannot be considered as a homogeneous group since they represent investors who may or may not maintain business relations with the companies on whose corporate boards they sit. Thus, it is not only the effect of female institutional directors as a whole on firm value that has been analysed, but also the impact of pressure-resistant female directors, who represent institutional investors (investment, pension and mutual funds) that only invest in the company, and do not maintain a business relation with the firm. We hypothesize that there is a non-linear association, specifically quadratic, between institutional and pressure-resistant female directors on boards and corporate performance. Our results report that female institutional directors on boards enhance corporate performance, but when they reach a certain threshold on boards (11.72 %), firm value decreases. In line with female institutional directors, pressure-resistant female directors on boards also increase firm value, but only up to a certain figure (12.71 % on boards), above which they have a negative impact on firm performance. These findings are consistent with an inverted U-shaped relationship between female institutional directors and pressure-resistant female directors and firm performance
Keys to success of a community of clinical practice in primary care : a qualitative evaluation of the ECOPIH project
The current reality of primary care (PC) makes it essential to have telemedicine systems available to facilitate communication between care levels. Communities of practice have great potential in terms of care and education, and that is why the Online Communication Tool between Primary and Hospital Care was created. This tool enables PC and non-GP specialist care (SC) professionals to raise clinical cases for consultation and to share information. The objective of this article is to explore healthcare professionals' views on communities of clinical practice (CoCPs) and the changes that need to be made in an uncontrolled real-life setting after more than two years of use. A descriptive-interpretative qualitative study was conducted on a total of 29 healthcare professionals who were users and non-users of a CoCP using 2 focus groups, 3 triangular groups and 5 individual interviews. There were 18 women, 21 physicians and 8 nurses. Of the interviewees, 21 were PC professionals, 24 were users of a CoCP and 7 held managerial positions. For a system of communication between PC and SC to become a tool that is habitually used and very useful, the interviewees considered that it would have to be able to find quick, effective solutions to the queries raised, based on up-to-date information that is directly applicable to daily clinical practice. Contact should be virtual - and probably collaborative - via a platform integrated into their habitual workstations and led by PC professionals. Organisational changes should be implemented to enable users to have more time in their working day to spend on the tool, and professionals should have a proactive attitude in order to make the most if its potential. It is also important to make certain technological changes, basically aimed at improving the tool's accessibility, by integrating it into habitual clinical workstations. The collaborative tool that provides reliable, up-to-date information that is highly transferrable to clinical practice is valued for its effectiveness, efficiency and educational capacity. In order to make the most of its potential in terms of care and education, organisational changes and techniques are required to foster greater use. The online version of this article (10.1186/s12875-018-0739-0) contains supplementary material, which is available to authorized users
Tratamientos Psicológicos Empíricamente Apoyados Para Adultos: Una Revisión Selectiva [Evidence-Based Psychological Treatments for Adults: A Selective Review]
Antecedentes: los tratamientos psicológicos han mostrado su efi cacia,
efectividad y efi ciencia para el abordaje de los trastornos mentales; no
obstante, considerando el conocimiento científi co generado en los últimos
años, no se dispone de trabajos de actualización en español sobre cuáles
son los tratamientos psicológicos con respaldo empírico. El objetivo fue
realizar una revisión selectiva de los principales tratamientos psicológicos
empíricamente apoyados para el abordaje de trastornos mentales en personas
adultas. Método: se recogen niveles de evidencia y grados de recomendación
en función de los criterios propuestos por el Sistema Nacional de Salud
de España (en las Guías de Práctica Clínica) para diferentes trastornos
psicológicos. Resultados: los resultados sugieren que los tratamientos
psicológicos disponen de apoyo empírico para el abordaje de un amplio
elenco de trastornos psicológicos. El grado de apoyo empírico oscila de bajo
a alto en función del trastorno psicológico analizado. La revisión sugiere
que ciertos campos de intervención necesitan una mayor investigación.
Conclusiones: a partir de esta revisión selectiva, los profesionales de la
psicología podrán disponer de información rigurosa y actualizada que les
permita tomar decisiones informadas a la hora de implementar aquellos
procedimientos psicoterapéuticos empíricamente fundamentados en
función de las características de las personas que demandan ayuda.
// Evidence-Based Psychological Treatments for Adults: A Selective Review. Background: Psychological treatments have shown their effi cacy,
effectiveness, and effi ciency in dealing with mental disorders. However,
considering the scientifi c knowledge generated in recent years, in the
Spanish context, there are no updating studies about empirically supported psychological treatments. The main goal was to carry out a selective
review of the main empirically supported psychological treatments for
mental disorders in adults. Method: Levels of evidence and degrees of recommendation were collected based on the criteria proposed by the Spanish National Health System (Clinical Practice Guidelines) for different
psychological disorders. Results: The results indicate that psychological
treatments have empirical support for the approach to a wide range of
psychological disorders. These levels of empirical evidence gathered range from low to high depending on the psychological disorder analysed.
The review indicates the existence of certain fi elds of intervention that
need further investigation. Conclusions: Based on this selective review,
psychology professionals will be able to have rigorous, up-to-date information that allows them to make informed decisions when implementing
empirically based psychotherapeutic procedures based on the characteristics of the people who require help
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Dietary α‐Linolenic Acid, Marine ω‐3 Fatty Acids, and Mortality in a Population With High Fish Consumption: Findings From the PREvención con DIeta MEDiterránea (PREDIMED) Study
Background: Epidemiological evidence suggests a cardioprotective role of α‐linolenic acid (ALA), a plant‐derived ω‐3 fatty acid. It is unclear whether ALA is beneficial in a background of high marine ω‐3 fatty acids (long‐chain n‐3 polyunsaturated fatty acids) intake. In persons at high cardiovascular risk from Spain, a country in which fish consumption is customarily high, we investigated whether meeting the International Society for the Study of Fatty Acids and Lipids recommendation for dietary ALA (0.7% of total energy) at baseline was related to all‐cause and cardiovascular disease mortality. We also examined the effect of meeting the society's recommendation for long‐chain n‐3 polyunsaturated fatty acids (≥500 mg/day). Methods and Results: We longitudinally evaluated 7202 participants in the PREvención con DIeta MEDiterránea (PREDIMED) trial. Multivariable‐adjusted Cox regression models were fitted to estimate hazard ratios. ALA intake correlated to walnut consumption (r=0.94). During a 5.9‐y follow‐up, 431 deaths occurred (104 cardiovascular disease, 55 coronary heart disease, 32 sudden cardiac death, 25 stroke). The hazard ratios for meeting ALA recommendation (n=1615, 22.4%) were 0.72 (95% CI 0.56–0.92) for all‐cause mortality and 0.95 (95% CI 0.58–1.57) for fatal cardiovascular disease. The hazard ratios for meeting the recommendation for long‐chain n‐3 polyunsaturated fatty acids (n=5452, 75.7%) were 0.84 (95% CI 0.67–1.05) for all‐cause mortality, 0.61 (95% CI 0.39–0.96) for fatal cardiovascular disease, 0.54 (95% CI 0.29–0.99) for fatal coronary heart disease, and 0.49 (95% CI 0.22–1.01) for sudden cardiac death. The highest reduction in all‐cause mortality occurred in participants meeting both recommendations (hazard ratio 0.63 [95% CI 0.45–0.87]). Conclusions: In participants without prior cardiovascular disease and high fish consumption, dietary ALA, supplied mainly by walnuts and olive oil, relates inversely to all‐cause mortality, whereas protection from cardiac mortality is limited to fish‐derived long‐chain n‐3 polyunsaturated fatty acids. Clinical Trial Registration URL: http://www.Controlled-trials.com/. Unique identifier: ISRCTN35739639
4to. Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad. Memoria académica
Este volumen acoge la memoria académica de la Cuarta edición del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad, CITIS 2017, desarrollado entre el 29 de noviembre y el 1 de diciembre de 2017 y organizado por la Universidad Politécnica Salesiana (UPS) en su sede de Guayaquil.
El Congreso ofreció un espacio para la presentación, difusión e intercambio de importantes investigaciones nacionales e internacionales ante la comunidad universitaria que se dio cita en el encuentro. El uso de herramientas tecnológicas para la gestión de los trabajos de investigación como la plataforma Open Conference Systems y la web de presentación del Congreso http://citis.blog.ups.edu.ec/, hicieron de CITIS 2017 un verdadero referente entre los congresos que se desarrollaron en el país.
La preocupación de nuestra Universidad, de presentar espacios que ayuden a generar nuevos y mejores cambios en la dimensión humana y social de nuestro entorno, hace que se persiga en cada edición del evento la presentación de trabajos con calidad creciente en cuanto a su producción científica.
Quienes estuvimos al frente de la organización, dejamos plasmado en estas memorias académicas el intenso y prolífico trabajo de los días de realización del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad al alcance de todos y todas
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