400 research outputs found

    Active Sums I

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    Given a generating family F of subgroups of a group G, closed under conjugation and with partial order compatible with inclusion, a new group S can be constructed, taking into account the multiplication in the subgroups and their mutual actions given by conjugation. The group S is called the active sum of F, has G as a homomorph and is such that S/Z(S) ' G/Z(G), where Z denotes the center. The basic question we investigate in this paper is: when is the active sum S of the family F isomorphic to the group G? The conditions found to answer this question are often of a homological nature. We show that the following groups are active sums of cyclic subgroups: free groups, semidirect products of cyclic groups, Coxeter groups, Wirtinger approximations, groups of order p3 with p an odd prime, simple groups with trivial Schur multiplier, and special linear groups SLn(q) with a few exceptions. We show as well that every finite group G such that G/G0 is not cyclic is the active sum of proper normal subgroups

    Spanish Adaptation of the Structural Empowerment Scale

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    The present study’s objective is to create a Spanish adaptation of the Conditions of Work Effectiveness Questionnaire II (CWEQ-II) by Laschinger, Finegan, Shamian, and Wilk (2004) in order to measure structural empowerment in an organizational context. To do so, this study was conducted in two distinct phases. In the first, a group of experts carried out a back-translation of the questionnaire and in the second phase, we analyzed the questionnaire’s internal structure (through exploratory and confirmatory factor analysis) and external validity. The resulting Spanish version of the questionnaire (CWEQ-S) demonstrated/exhibited good factor structure and good psychometric properties as far as reliability and validity are concerned

    La investigación del rayo en Colombia: Parámetros del rayo, sistemas de protección, evaluación de riesgos y sistemas de alerta

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    This paper summarizes the most important studies on lightning phenomenonin Colombia during the last 25 years. In order to give an in-depthtreatment to specific aspects and advances in lightning research, thisreview has been divided in four sections: lightning parameters, lightningprotection systems, risk assessment and warning systems. At the end ofthe paper, the advances and challenges on lightning research in Colombiaare presented.Este artículo sintetiza los estudios más importantes sobre la investigacióndel rayo en Colombia durante los últimos 25 años. Para dar un tratamientodetallado a aspectos específicos y avances relacionados con la investigacióndel rayo, esta revisión ha sido dividida en cuatro secciones: estudio delos parámetros del rayo, sistemas de protección, evaluación de riesgosy sistemas de alerta. El artículo finaliza con avances y retos futuros quepresenta la investigación de rayos en Colombia

    Caracterización de trenes de descargas preliminares en rayos nube a tierra negativos registrados durante una temporada de lluvias en la Sabana de Bogotá, Colombia

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    Lightning-generated electric field measurement is used to characterize cloud-to-ground (CG) flashes. Prior to the first return stroke (FRS), these signals sometimes exhibit a pulse train, known as preliminary breakdown pulses (PBP), whose study provides information about the first event that originate the breakdown process inside the cloud. Considering that characteristics of PBPs may change according to geographical conditions, in this work, six parameters (temporal and magnitude) associated with 69 trains identified in negative CG flashes that occurred in the Bogota savannah, Colombia were analyzed. The signatures were recorded in 2017 using a fast response antenna (10 MHz bandwidth), a 100 ns sampling time and a window of 500 ms. Among the most relevant results, it was found that the train duration ( ) varied from 0.5 ms up to 5.2 ms with arithmetic mean (AM) of 1.74 ms, while the time interval between the peak of the train and the FRS (PBP-FRS) had an AM and a geometric mean (GM) of 35.7 ms and 10.2 ms, respectively. On the other hand, the ratio between the peak value of the PBP and its FRS ( ) exhibited an AM of 0.7 and a GM of 0.56. It was concluded that PBP train starts with low amplitude pulses, later increases its magnitude in the central region and decreases at the end. Furthermore, bipolar pulses with similar polarity to that of the FRS were identified at the beginning and in the middle of the train, while unipolar pulses were observed at the end of the signatures.La medición del campo eléctrico generado por rayos es comúnmente usada para caracterizar rayos nube-tierra (CG). Previo a la primera descarga de retorno (FRS), estas señales exhiben algunas veces un tren de pulsos conocido como pulsos de descargas preliminares (PBP), cuyo estudio proporciona información sobre el primer evento que origina el proceso de descarga dentro de la nube. Considerando que las características de los PBP pueden cambiar de acuerdo con las condiciones geográficas, en este trabajo se analizaron seis parámetros (temporales y de magnitud) asociados a 69 trenes identificados en rayos CG negativos ocurridos en la Sabana de Bogotá, Colombia. Las señales se registraron en 2017 usando una antena de respuesta rápida (ancho de banda de 10 MHz), un tiempo de muestreo de 100 ns y una ventana de 500 ms. Dentro de los resultados más relevantes se encontró que la duración del tren ( ) varió entre 0.5 ms y 5.2 ms con una media aritmética (AM) de 1.74 ms, mientras el tiempo entre el pico del tren y el FRS (PBP-FRS) tuvo una AM y una media geométrica (GM) de 35.7 ms y 10.2 ms, respectivamente. Por su parte, la relación entre el pico del PBP y su FRS ( ) exhibió una AM de 0.7 y una GM de 0.56. Se concluye que el tren comienza con pulsos de baja amplitud, aumenta su magnitud en la región central y disminuye al final. Adicionalmente, se identificaron pulsos bipolares con polaridad similar a la FRS al principio y en la mitad del tren, mientras pulsos unipolares fueron observados al final de las señales

    Spatial partial coherence in Young's interferograms

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    Young's interferograms with high visibility reveals a high degree of spatial coherence of first order. But, spatially partial coherence of second order can be observed when it interferes itself through a compensated Michelson's interferometer attached at the exit of the Young's slit pair. We show that the patterns at the exit of the Michelson's interferometer are Young's interferograms with modulation fringes, which allow an estimation of the degree of the high order spatial coherence

    Modeling the effect of the electrode potential in SERS by electronic structure calculations.

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    Surface Enhanced Raman Spectroscopy (SERS), due to the ability of greatly intensify the weak Raman signal of molecules adsorbed to metal surfaces, has proven to be a very useful tool to investigate changes in the electronic structure of metal-molecule surface complex. A deep knowledge of the electronic structure of these metal-molecule hybrid systems is key in electrochemistry, catalysis, plasmonics, molecular electronics, and in the development of selective and ultra-sensitive analytical sensors. The origin of this huge enhancement in SERS is due to two contributions: the electromagnetic (EM), related to surface plasmons, and the chemical mechanism, due to resonant charge transfer (CT) process between the adsorbate and the metal (CTSERS). Unfortunately, the SERS implies very complex phenomena where the molecule and the metal nanoparticle are involved. This fact makes challenging to build realistic theoretical models that take into account both the metal and the molecule at quantum level. We propose a methodology, based on DFT and ab initio electronic calculations, to simulate the effect of the electrode potential on the absorption, on the charge transfer states energies, and on the electronic excitations in metal-molecule hybrid systems from a microscopic point of view. This methodology consists on the prediction of Raman intensities from ab initio calculations of the geometries or the energy gradients at the excited states Franck-Condon point, bringing the possibility to predict the intensities in CTSERS as well as in resonance Raman without the need to know the excited state geometries, not always feasible to compute. The microscopic model adopted to mimic the effect of the interphase electric potential consist in a molecule adsorbed to a linear silver cluster [Agn-Adsorbate]q, were n is the number of silver atoms, and the total charge of the system (q) is zero for n=2 and q=±1 for n=1, 3 and 7.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Validation of the Spanish Version of the Work Group Emotional Intelligence Profile Short Version (WEIP-S) in the Sports Context.

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    Emotional intelligence (EI) is related to better performance in sports. To measure this construct, many tools have been developed and validated in the sports context. However, these tools are based on an individual’s ability to manage their own emotions, but do not consider the emotions of the rest of the team (teammates, coaches, etc.). In this regard, the Workgroup Emotional Intelligence Profile short version (WEIP-S) is a self-reported measure designed to measure the EI of individuals who are part of a team. The aim of this study was to validate the WEIP-S structure to measure EI in the sports context, and to analyze the psychometric properties of this tool in the sample in terms of validity and reliability. A cross-sectional study was conducted among 273 athletes to examine the reliability, factor structure, and evidence of validity (convergent, discriminant, nomological, and concurrent) of the WEIP-S. Confirmatory factor analysis showed that the original four-factor structure is the most appropriate for the sports context. Composite reliability was adequate for all factors except management of one’s own emotions, which also showed poor convergent validity. Evidence of convergent, discriminant, and nomological validity are discussed. This study represents an advance in the use of specific scales to measure EI in the sports context.post-print1021 K

    Intelligence and video games: beyond “brain-games”

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    Video games are among the most popular leisure activities in current Western societies. Psychology research has shown correlations, at the latent level, between intelligence and video games ranging from 0.60 to 0.93. Here we analyze whether video games genre can account for this range of correlations by testing one hundred and thirty-four participants playing ten video games of different genres for iPad® and WiiU® (Art of Balance®, Blek, Crazy Pool, EDGE®, Hook, Rail Maze, SkyJump, Space Invaders, Splatoon® and Unpossible) within a controlled playing environment. Gaming performance was correlated with standard measures of fluid reasoning, visuospatial ability, and processing speed. Results revealed a correlation value of 0.79 between latent factors representing general intelligence (g) and video games general performance (gVG). This finding leads to conclude that: (1) performance intelligence tests and video games is supported by shared cognitive processes and (2) brain-games are not the only genre able to produce performance measures comparable to intelligence standardized tests. From a theoretical perspective, the observed result supports the principle of the indifference of the indicator that has been addressed in intelligence research across decade

    Behavior patterns in hormonal treatments using fuzzy logic models

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    Assisted reproductive technologies are a combination of medical strategies designed to treat infertility patients. Ideal stimulation treatment has to be individualized, but one of the main challenges which clinicians face in the everyday clinic is how to select the best medical protocol for a patient. This work aims to look for behavior patterns in this kind of treatments, using fuzzy logic models with the objective of helping gynecologists and embryologists to make decisions that could improve the process of in vitro fertilization. For this purpose, a real-world dataset composed of one hundred and twenty-three (123) patients and five hundred and fifty-nine (559) treatments applied in relation to such patients provided by an assisted reproduction clinic, has been used to obtain the fuzzy models. As conclusion, this work corroborates some known clinic experiences, provides some new ones and proposes a set of questions to be solved in future experiments.Ministerio de Economía y Competitividad TIN2013-46928-C3-3-RMinisterio de Economía y Competitividad TIN2016-76956- C3-2-RMinisterio de Economía y Competitividad TIN2015-71938-RED
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