Coupled electric and magnetic dipole formulation for planar arrays of dipolar particles: metasurfaces with various electric and/or magnetic meta-atoms per unit cell

The optical properties of infinite planar array of scattering particles, metasurfaces and metagratings, are attracting special attention lately for their rich phenomenology, including both plasmonic and high-refractive-index dielectric meta-atoms with a variety of electric and magnetic resonant responses. Herein we derive a coupled electric and magnetic dipole (CEMD) analytical formulation to describe the reflection and transmission of such periodic arrays, including specular and diffractive orders, valid in the spectral regimes where only dipolar multipoles are needed. Electric and/or magnetic dipoles with all three orientations arising in turn from a single or various meta-atoms per unit cell are considered. The 2D lattice Green function is rewritten in terms of a 1D (chain) version that fully converges and can be easily calculated. Modes emerging as poles of such lattice Green function can be extracted. This formulation can be applied to investigate a wealth of plasmonic, all-dielectric, and hybrid metasurfaces/metagratings of interest throughout the electromagnetic spectrum.Comment: 8 pages, 4 figure

La extradición en el gobierno de la Prosperidad Democrática: caracterización y análisis de la extradición pasiva a Estados Unidos entre 2011 y 2014

21 p.La extradición, en su concepción clásica, es un instrumento de cooperación judicial internacional o de asistencia judicial entre Estados soberanos. Su carácter instrumental respecto del ejercicio del ius puniendi por los Estados se orienta a que las fronteras territoriales no constituyan un obstáculo absoluto a sus pretensiones punitivas. No obstante, también son múltiples los debates alrededor de la cesión de soberanía que implica este tipo de figuras, frente a los cuales se responde que la naturaleza de la fuente específica que las regula -los tratados- y el principio de reciprocidad -cuyo fundamento es el acuerdo interestatal y el reconocimiento de un igual estatus internacional de los Estados- resultan ser un reflejo de esta soberanía.El presente capítulo forma parte del proceso de investigación formativa adelantado en el marco del Observatorio de Cooperación Internacional y Administración de Justicia Penal de la Universidad Católica de Colombia, en el marco del proyecto “Análisis y monitoreo de los procesos de extradición de nacionales colombianos a los Estados Unidos de América”.Introducción Sobre el proceso de investigación: breve mención de la metodología Antecedentes: la extradición como mecanismo de lucha contra las drogas La extradición como institución jurídica Caracterización de las solicitudes y los conceptos de extradición, periodo 2010-2014 Sobre las solicitudes de extradición con Estados Unido

Sustentación de caso: propuesta de un plan estratégico del ingreso al mercado peruano de una empresa del sector fast fashion

El presente documento se centrará en el análisis y formulación de una estrategia para el ingreso de UNIQLO en el mercado peruano, ya que esta es la marca más importante del Grupo Fast Retailing y actualmente está en búsqueda de su expansión

Impacto del sistema unitario de compensación regional de pagos sucres en el comercio bilateral Ecuador - Venezuela período 2010-2014

Negocios InternacionalesEn esta investigación resulta de gran importancia determinar el Impacto del Sistema Unitario de Compensación Regional de Pagos SUCRE en el Comercio Bilateral Ecuador Venezuela período 2010-2014, como canalizador eficiente de los pagos internacionales. Para lograr un adecuado análisis, se divide en varios capítulos, empezando por el nacimiento y evolución del intercambio comercial bilateral, y las perspectivas y potencialidades de la utilización del sucre como Unidad de cuenta en las Operaciones de Comercio Exterior.This research is of great importance to determine the impact of the Unitary System Regional Payments Bilateral Trade SUCRE Ecuador in Venezuela period 2010-2014, as an efficient channel for international payments. For proper analysis, it is divided into several chapters, beginning with the birth and evolution of bilateral trade, and the prospects and potential of the use of the sucre as the Unit of Account in Foreign Trade Operations

Modelo de aceptación tecnológica en los canales digitales para la adquisición de productos agrícolas frescos

Purpose: This study aimed to determine the factors influencing the use of digital channels for purchasing fresh agricultural products. Design/Methodology: A structural equation model was developed, employing confirmatory factor analysis to evaluate the seven constructs of the Unified Theory of Acceptance and Use of Technology 2 (performance expectancy, effort expectancy, social influence, facilitating conditions, hedonic motivation, price value, and habit). This assessment was conducted on a sample of 175 consumers of agricultural products. Findings: All variables, except for facilitating conditions, were found to significantly influence consumers’ intention to use digital channels for purchasing fresh agricultural products. Additionally, habit and behavioral intention were identified as key determinants of use behavior. Conclusions: The research concludes that prior experience, gender, and age have a positive impact on consumers’ intention to use digital channels for purchasing fresh agricultural products. It is recommended that digital marketing strategies in the agricultural sector take these factors into account to enhance the adoption of digital channels. Originality: This study is the first to apply the UTAUT2 model to investigate consumers’ online purchase of fresh agricultural products. Notably, it addresses a research gap by incorporating consumer variables and focusing on an underexplored niche.Objetivo: determinar los factores asociados al uso de canales digitales para la adquisición de bienes agrícolas frescos. Diseño/metodología: se realizó un modelo de ecuaciones estructurales a partir de un análisis factorial confirmatorio que permitió evaluar los siete constructos de la Teoría Unificada de Aceptación y Uso de Tecnología 2 - UTAUT2- (expectativa de desempeño, expectativa de esfuerzo, influencia social, condiciones facilitadoras, motivación hedónica, valor del precio y hábito) en una muestra de 175 consumidores de productos agrícolas. Resultados: se halló que todas las variables, excepto las condiciones facilitadoras, influyen significativamente en la intención de los consumidores de usar canales digitales para adquirir productos agrícolas frescos. Además, el hábito y la intención conductual se identificaron como antecedentes clave del comportamiento de uso. Conclusiones: la investigación concluye que la experiencia, el género y la edad tienen un impacto positivo en la intención de utilizar canales digitales para la compra de bienes agrícolas frescos. Se sugiere que las estrategias de marketing digital en el sector agropecuario deben considerar estos factores para optimizar la adopción de canales digitales. Originalidad: este estudio es el primero en aplicar el modelo UTAUT2 a la compra digital de productos agrícolas frescos, llenando un vacío en la investigación al incorporar variables de consumo y enfocarse en un nicho poco explorado

Aceptación tecnológica de las plataformas virtuales en estudiantes universitarios: un análisis en tiempos de pandemia

The global health emergency generated by Covid-19 has transformed the traditional learning model, generating a generalized sudden foray into virtual learning environments; process in which ease of use, perceived usefulness, and attitude toward technology play a fundamental role in the acceptance of virtual platforms as a tool for the teaching-learning process. The objective was to evaluate the acceptance of the use of virtual platforms by university students in the times of the Coronavirus Pandemic (COVID-19). A confirmatory factor analysis was performed in order to evaluate the four constructs of the TAM technological acceptance model (perceived usefulness, ease of use, attitude, and intention to use) in a sample of 200 undergraduate students. It was concluded that the perceived utility and ease of use are antecedents of the attitude and this time it is decisive of the intention to use virtual platforms in the academic activities of university students. Similarly, it was found that gender does not affect the acceptance of technology in the use of virtual platforms

Modelo de ecuaciones estructurales para la evaluación de competencias tecnológicas en estudiantes universitarios

The digital skills of university students are a determinant in their training process, since they provide fundamental tools for information management and the development of problems immersed in their academic activities, even more so, given the challenge imposed by digitization due to the incursion and the accelerated use of information and communication technologies in the teaching and learning process in times of pandemic. The evaluation of digital skills allows, on the one hand, to verify if students have the necessary skills to adapt to educational environments and, on the other, to design strategies that guarantee the knowledge that students require to maintain a teaching and learning process. successful. Therefore, the objective of this research was to evaluate the factors associated with digital skills in 256 university students, through a four-construct structural equation model, validated through internal consistency, goodness of fit, and validity. convergent and divergent. As a result, it was determined that the digital competences of the students are determined by the information, communication, technological and organizational capacities, acquired by the apprentice in his training process. It was concluded that the characterization of digital skills that allow the development of academic activities in a virtual environment, such as the search for information for the development of tasks, cooperative work between students and the typographic edition and image of academic documents.Las habilidades digitales de los estudiantes universitarios son un determinante en su proceso de formación, pues proporcionan herramientas fundamentales para la gestión de la información y el desarrollo de problemas inmersos en sus actividades académicas, más aún, ante el reto que impone la digitalización por la incursión y el acelerado uso de las tecnologías de la información y comunicación en el proceso de enseñanza y aprendizaje en tiempos de pandemia. La evaluación de las habilidades digitales permite, por un lado, verificar si los estudiantes poseen las capacidades necesarias para adaptarse a los entornos educativos y, por el otro, diseñar estrategias que garanticen el conocimiento que requieren los estudiantes para mantener un proceso de enseñanza y aprendizaje exitoso. Por lo anterior, el objetivo de esta investigación fue evaluar los factores asociados a las habilidades digitales en 256 estudiantes universitarios, a través de un modelo de ecuaciones estructurales de cuatro constructos, validado por medio de la consistencia interna, la bondad de ajuste y la validez convergente y divergente. Como resultado se determinó que las competencias digitales de los estudiantes están determinadas por las capacidades de información, de comunicación, tecnológicas y de organización, adquiridas por el aprendiz en su proceso formativo. Se concluye que la caracterización de habilidades digitales permite el desarrollo de actividades académicas en un entorno virtual, tales como la búsqueda de información para el desarrollo de labores, el trabajo cooperativo entre estudiantes y la edición tipográfica e imagen de documentos académicos

Exon-Intron Structure and Evolution of the Lipocalin Gene Family

Innovación EducativaThe Lipocalins are an ancient protein family whose expression is currently confirmed in bacteria, protoctists, plants, arthropods, and chordates. The evolution of this protein family has been assessed previously using amino acid sequence phylogenies. In this report we use an independent set of characters derived from the gene structure (exon-intron arrangement) to infer a new lipocalin phylogeny. We also present the novel gene structure of three insect lipocalins. The position and phase of introns are well preserved among lipocalin clades when mapped onto a protein sequence alignment, suggesting the homologous nature of these introns. Because of this homology, we use the intron position and phase of 23 lipocalin genes to reconstruct a phylogeny by maximum parsimony and distance methods. These phylogenies are very similar to the phylogenies derived from protein sequence. This result is confirmed by congruence analysis, and a consensus tree shows the commonalities between the two source trees. Interestingly, the intron arrangement phylogeny shows that metazoan lipocalins have more introns than other eukaryotic lipocalins, and that intron gains have occurred in the C-termini of chordate lipocalins. We also analyze the relationship of intron arrangement and protein tertiary structure, as well as the relationship of lipocalins with members of the proposed structural superfamily of calycins. Our congruence analysis validates the gene structure data as a source of phylogenetic information and helps to further refine our hypothesis on the evolutionary history of lipocalins.2015-09-1

Grasshopper Lazarillo, a GPI-anchored Lipocalin, increases Drosophila longevity and stress resistance, and functionally replaces its secreted homolog NLaz

Producción CientíficaLazarillo (Laz) is a glycosyl-phosphatidylinositol (GPI)-linked glycoprotein first characterized in the developing nervous system of the grasshopper Schistocerca americana. It belongs to the Lipocalins, a functionally diverse family of mostly secreted proteins. In this work we test whether the protective capacity known for Laz homologs in flies and vertebrates (NLaz, GLaz and ApoD) is evolutionarily conserved in grasshopper Laz, and can be exerted from the plasma membrane in a cell-autonomous manner. First we demonstrate that extracellular forms of Laz have autocrine and paracrine protecting effects for oxidative stress-challenged Drosophila S2 cells. Then we assay the effects of overexpressing GPI-linked Laz in adult Drosophila and whether it rescues both known and novel phenotypes of NLaz null mutants. Local effects of GPI-linked Laz inside and outside the nervous system promote survival upon different stress forms, and extend lifespan and healthspan of the flies in a cell-type dependent manner. Outside the nervous system, expression in fat body cells but not in hemocytes results in protection. Within the nervous system, glial cell expression is more effective than neuronal expression. Laz actions are sexually dimorphic in some expression domains. Fat storage promotion and not modifications in hydrocarbon profiles or quantities explain the starvationedesiccation resistance caused by Laz overexpression. This effect is exerted when Laz is expressed ubiquitously or in dopaminergic cells, but not in hemocytes. Grasshopper Laz functionally restores the loss of NLaz, rescuing stress-sensitivity as well as premature accumulation of aging-related damage, monitored by advanced glycation end products (AGEs). However Laz does not rescue NLaz courtship behavioral defects. Finally, the presence of two new Lipocalins with predicted GPI-anchors in mosquitoes shows that the functional advantages of GPI-linkage have been commonly exploited by Lipocalins in the arthropodan lineage

Sex-dependent modulation of longevity by two Drosophila homologues of human Apolipoprotein D, GLaz and NLaz

Producción CientíficaApolipoprotein D (ApoD), a member of the Lipocalin family, is the gene most up-regulated with age in the mammalian brain. Its expression strongly correlates with aging-associated neurodegenerative and metabolic diseases. Two homologues of ApoD expressed in the Drosophila brain, Glial Lazarillo (GLaz) and Neural Lazarillo (NLaz), are known to alter longevity in male flies. However, sex differences in the aging process have not been explored so far for these genes. Here we demonstrate that NLaz alters lifespan in both sexes, but unexpectedly the lack of GLaz influences longevity in a sex-specific way, reducing longevity in males but not in females. While NLaz has metabolic functions similar to ApoD, the regulation of GLaz expression upon aging is the closest to ApoD in the aging brain. A multivariate analysis of physiological parameters relevant to lifespan modulation uncovers both common and specialized functions for the two Lipocalins, and reveals that changes in protein homeostasis account for the observed sex-specific patterns of longevity. The response to oxidative stress and accumulation of lipid peroxides are among their common functions, while the transcriptional and behavioral response to starvation, the pattern of daily locomotor activity, storage of fat along aging, fertility, and courtship behavior differentiate NLaz from GLaz mutants. We also demonstrate that food composition is an important environmental parameter influencing stress resistance and reproductive phenotypes of both Lipocalin mutants. Since ApoD shares many properties with the common ancestor of invertebrate Lipocalins, we must benefit from this global comparison with both GLaz and NLaz to understand the complex functions of ApoD in mammalian aging and neurodegeneration