Near-field electromagnetic wave scattering from random self-affine fractal metal surfaces: Spectral dependence of local field enhancements and their statistics in connection with surface-enhanced Raman scattering

11 págs.; 10 figs.By means of rigorous numerical simulation calculations based on the Green's theorem integral equation formulation, we study the near electromagnetic field in the vicinity of very rough, one-dimensional self-affine fractal surfaces of Ag, Au, and Cu (for both vacuum and water propagating media) illuminated by a p-polarized field. Strongly localized enhanced optical excitations (hot spots) are found, with electric field intensity enhancements of close to 4 orders of magnitude and widths below a tenth of the incoming wavelength. These effects are produced by the roughness-induced surface-plasmon polariton excitation. We study the characteristics of these optical excitations as well as other properties of the surface electromagnetic field, such as its statistics (probability density function, average, and fluctuations), and their dependence on the excitation spectrum (in the visible and near-infrared regions). Our study is relevant to the use of self-affine fractals as surface-enhanced Raman scattering substrates, where large local and average field enhancements are desired. ©2000 American Physical SocietyThis work was supported by the Spanish Dirección General de Ensenñanza Superior e Investigación Científica y Técnica, through Grant No. PB97-1221. We also thank the Mexican-Spanish CONACYT-CSIC program for partial travel support.Peer Reviewe

Collective electromagnetic emission from molecular layers on metal nanostructures mediated by surface plasmons

6 págs.; 3 figs.; PACS number s : 73.20.Mf, 78.30. j, 78.67.Bf, 42.25.FxCollective electromagnetic processes stemming from molecular emission close to complex nanostructured metal surfaces pumped at and/or near surface-plasmon resonances are theoretically investigated. A classical electrodynamics model is used to describe macroscopically the surface molecular layer emission. Generalized Fresnel coefficients are analytically obtained for planar surfaces, indeed predicting collective quenching for redshifted emission at given angles. The model is introduced into a scattering formulation based on surface integral equations in order to explore collective spontaneous emission near metallic nanoantennas and surface-enhanced Raman scattering. Frequency-shifted near-field patterns and properly defined enhancement factors are obtained that manifest collective processes and cannot be simply inferred from calculations of near fields at the pump frequency. © 2007 The American Physical Society.This work was supported in part by the Spanish “Ministerio de Educación y Ciencia” Grant Nos. FIS2006-07894 and FIS2004-0108 and “Comunidad de Madrid” Grant No. S-0505/TIC-0191 and V.G.’s Ph.D. scholarshipPeer Reviewe

Validation of the Scale of Basic Psychological Needs towards Physical Exercise, with the Inclusion of Novelty

The purpose of this study was to validate and adapt to the Spanish context of Physical Education, the Spanish version of the Scale of Basic Psychological Needs in the context of physical exercise, with the incorporation of novelty to the scale. The sample that took part in the study was 2372 people from 16 to 48 years old from the province of Almeria. In order to analyze the psychometric properties of the scale, several analyses have been carried out. The results have offered support both for the eight-factor structure and for the higher-order double model where the eight subscales are joined into two constructs called frustration and satisfaction. The structure of both models was invariant with respect to gender and age. Cronbach’s alpha values were above 0.70 in the subscales and scales; and adequate levels of temporal stability. In addition, the subfactors pertaining to the satisfaction of basic psychological needs positively predicted the intrinsic motivation for physical activity, while each of the subfactors of the frustration of psychological needs predicted it negatively. The results of this study provide evidence of the reliability and validity of the BPNS in the Spanish context of physical activity

Instalación de paneles fotovoltaicos para el suministro eléctrico de una comunidad de vecinos en la ciudad de Zaragoza.

Actualmente, vivimos en una sociedad fuertemente dependiente de la energía, más en concreto de la energía eléctrica, que se está imponiendo cada vez en mayor medida como vector energético en el desempeño de la mayor parte de las actividades humanas. A través de este proyecto, se pretende aportar una alternativa limpia y renovable a la producción actual de energía, con la instalación de placas fotovoltaicas que abastezcan de electricidad a un bloque de viviendas, logrando reducir la huella de carbono y los costes asociados a la importación de combustibles fósiles y, además, proporcionando un ahorro económico a los consumidores para el caso concreto de una comunidad de vecinos situada en la ciudad de Zaragoza.<br /

Knowledge management and intellectual capital in the business model innovation of Costa Rican manufacturing firms

El propósito de este artículo es analizar el impacto de la gestión del conocimiento y el capital intelectual en la capacidad de las empresas para generar innovación en el modelo de negocio. Para evaluar las hipótesis propuestas, realizamos encuestas en una muestra de 100 empresas manufactureras costarricenses y analizamos los datos utilizando el Modelo de Ecuaciones Estructurales por Mínimos Cuadrados Parciales (PLS-SEM). Los resultados del estudio muestran que la gestión del conocimiento contribuye positivamente al desarrollo de innovaciones en el modelo de negocio. De igual forma, el capital intelectual tiene una influencia positiva directa en la innovación del modelo de negocio, sin embargo, esta relación depende de la existencia de prácticas dirigidas a promover la gestión del conocimiento en las empresasThe purpose of this article is to analyze the impact of knowledge management and intellectual capital on the ability of companies to generate business model innovation. To evaluate the proposed hypotheses, we surveyed a final sample of 100 Costa Rican manufacturing companies and analyzed the data using Partial Least Squares Structural Equation Modeling (PLS-SEM). The results show that knowledge management positively contributes to the development of business model innovations. Similarly, intellectual capital has a direct positive influence on business model innovation. However, the direct contribution intellectual capital depends on the adoption of practices that encourage knowledge management in companie

Estrategias lúdico-pedagógicas para el fortalecimiento de los estados emocionales en los estudiantes del grado quinto de la institución educativa Ricaurte

A partir de la experiencia en la Institución Educativa Ricaurte ubicada en el municipio de Soacha, Cundinamarca, los docentes se han visto enfrentados a diferentes retos en el actuar escolar debido al contexto social y familiar de la comunidad que allí se interrelaciona; identificándose necesidades tanto sociales como emocionales en los estudiantes de quinto grado, las cuales han manifestado con preocupación los docentes de la institución. También se evidencia que el contexto social y familiar de los estudiantes incide negativamente en la motivación de cada uno, ya que ellos no solo deben reconfigurar su forma de aprender, también, deben adaptarse a las condiciones sociales en las cuales interactúan en su diario vivir sin el apoyo de su contexto familiar en varios casos. Es por esto, que los docentes han llevado sus esfuerzos para lograr una articulación entre las posibilidades y limitaciones de cada estudiante y las exigencias de los lineamientos curriculares de la institución, y así poder brindarles actividades y espacios que los motiven a tener una mejor disposición ante su desempeño académico y en el control de sus emociones. El objetivo principal de este proyecto es explorar y ubicar los principales referentes teóricos, metodológicos y prácticos en torno al uso de las estrategias lúdico-pedagógicas encaminadas a fortalecer los estados emocionales en los niños. Asimismo, identificar y diseñar estrategias lúdico pedagógicas las cuales fortalezcan sus emociones, y permitan que tanto los estudiantes como los docentes puedan reconocerlas y aprendan a controlarlas en el contexto escolar. Desde los registros memorísticos de varios docentes de la institución y la experiencia docente de los investigadores, se logró diseñar una cartilla que pretende orientar de una manera más personalizada el proceso de los estados emocionales de sus estudiantes, con el fin de que su proceso personal y académico se vea beneficiado.Con el fin de fortalecer los estados emocionales funcionales en los estudiantes, se crea y diseña una cartilla, que pretende orientar de una manera más personalidad estos estados y la cual será un soporte para los docentes.From the experience in the Institución Educativa Ricaurte located in the municipality of Soacha, Cundinamarca, teachers have been faced with different challenges in the school performance due to the social and family context of the community that interrelates there; identifying both social and emotional needs in fifth grade students, which have been expressed with concern by the teachers of the institution. It is also evident that the social and family context of the students has a negative impact on the motivation of each one, since they must not only reconfigure their way of learning, but also adapt to the social conditions in which they interact in their daily lives without the support of their family context in many cases. For this reason, teachers have made efforts to achieve an articulation between the possibilities and limitations of each student and the demands of the curricular guidelines of the institution, and thus be able to provide activities and spaces that motivate them to have a better disposition to their academic performance and control of their emotions. The main objective of this research is to explore and locate the main theoretical, methodological and practical references regarding the use of ludic- pedagogical strategies aimed at strengthening children's functional states. In order to design playful-pedagogical strategies that strengthen their emotions, and allow both students and teachers to recognize them and learn to control them in the school context. From the memory records of several teachers of the institution and the teaching experience of the researchers, it was possible to design a booklet that aims to guide in a more personalized way the process of the emotional states of their students, so that their personal and academic process is benefited

Acinetobacter Baumannii Maintains Its Virulence After Long-Time Starvation

Acinetobacter baumannii is a cause of healthcare-associated infections. Although A. baumannii is an opportunistic pathogen, its infections are notoriously difficult to treat due to intrinsic and acquired antimicrobial resistance, often limiting effective therapeutic options. A. baumannii can survive for long periods in the hospital environment, particularly on inanimate surfaces. Such environments may act as a reservoir for cross-colonization and infection outbreaks and should be considered a substantial factor in infection control practices. Moreover, clothing of healthcare personnel and gadgets may play a role in the spread of nosocomial bacteria. A link between contamination of hospital surfaces and A. baumannii infections or between its persistence in the environment and its virulence has not yet been established. Bacteria under stress (i.e., long-term desiccation in hospital setting) could conserve factors that favor infection. To investigate whether desiccation and/or starvation may be involved in the ability of certain strains of A. baumannii to retain virulence factors, we have studied five well-characterized clinical isolates of A. baumannii for which survival times were determined under simulated hospital conditions. Despite a considerable reduction in the culturability over time (up to 88% depending on strain and the condition tested), some A. baumannii strains were able to maintain their ability to form biofilms after rehydration, addition of nutrients, and changing temperature. Also, after long-term desiccation, several clinical strains were able to grow in the presence of non-immune human serum as fine as their non-stressed homologs. Furthermore, we also show that the ability of bacterial strains to kill Galleria mellonella larvae does not change although A. baumannii cells were stressed by long-term starvation (up to 60 days). This means that A. baumannii can undergo a rapid adaptation to both the temperature shift and nutrients availability, conditions that can be easily found by bacteria in a new patient in the hospital setting.Research in our laboratory is supported by the Spanish Instituto de Salud Carlos III, Spain (grant PI16/01103 to José Ramos-Vivas) and the Plan Nacional de I+D+i 2008-2011 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI RD12/0015) - co-financed by European Development Regional Fund "A way to achieve Europe" ERDF. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Chitosan selectivity for removing cadmium (II), copper (II), and lead (II) from aqueous phase: pH and organic matter effect

"The aim of this study was to investigate the selectivity of chitosan for cadmium, copper and lead in the presence and absence of natural organic matter (NOM) in different pH solutions. Adsorption isotherms of one and three adsorbates at initial concentration of 5–100 mg/L were carried out in batch reactors at pH 4, 5, or 7 and 25 °C in reactive and clarified water. The chitosan employed had a MW of 107.8 × 103 g/mol and degree of acetylation (DA) of 33.7%. The chitosan adsorption capacity at pH 4 in reactive water was 0.036, 0.016, 0.010 mmol/g for Pb2+, Cd2+, and Cu2+, respectively, and it decreased for Pb2+ and Cd2+ in clarified water. Conversely, experiments carried out in clarified water showed that the cadmium adsorption capacity of chitosan was enhanced about three times by the presence of NOM at pH 7: an adsorption mechanism was proposed. Furthermore, it was found that the biosorbent selectivity, in both reactive and clarified water at pH 4, was as follows Cu2+ > Cd2+ > Pb2+. Finally, the preliminary desorption experiments of Cd2+ conducted at pH 2 and 3 reported 68 and 44.8% of metal desorbed, which indicated that the adsorption mechanism occurred by electrostatic interactions and covalent bonds.