1,094 research outputs found

    Two-meson cloud contribution to the baryon antidecuplet self-energy

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    We study the self-energy of the SU(3) antidecuplet coming from two-meson virtual clouds. Assuming that the exotic Theta+ belongs to an antidecuplet representation with N(1710) as nucleon partner, we derive effective Lagrangians that describe the decay of N(1710) into N pi pi with two pions in s- or p-wave. It is found that the self-energies for all members of the antidecuplet are attractive, and the larger strangeness particle is more bound. From two-meson cloud, we obtain about 20 % of the empirical mass splitting between states with different strangeness.Comment: 4 pages, 2 figures, 1 table, Talk given at the 10th International Conference on Baryons (Baryons04), Palaiseau (France), October 25-29, 200

    Movimientos comunes e idiosincráticos en las tasas de cambio de América Latina

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    En este artículo proponemos una aproximación teórica y empírica simple para diferenciar los movimientos comunes e idiosincráticos de las tasas de cambio de cinco economías latinoamericanas: Brasil, Chile, Colombia, México y Perú. Nuestra aproximación permite distinguir los efectos resultantes de un factor común regional y los diferenciales de los fundamentales macroeconómicos sobre las tasas de cambio de la región. Esta metodología y estrategia de estimación es aplicable tanto para datos de alta como de baja frecuencia. Se presenta evidencia que el factor común regional tiene un impacto significativo en la dinámica de las tasas de cambio seleccionadas. En nuestras estimaciones, la relación entre las tasas de cambio y el factor común es contemporánea y estable durante el periodo de estudio analizado.We propose a simple theoretical and empirical approach to differentiate between common and idiosyncratic exchange rate movements in 5 Latin-American economies: Brazil, Chile, Colombia, Mexico, and Peru. Our approach allows us to distinguish the effects on exchange rates of a regional exchange rate common factor and macroeconomic fundamentals differentials. The methodology and estimation strategy are suitable for both low and high frequency settings. We provide evidence that the regional common factor has a significant effect on the dynamics of the Latin-American exchange rates. In our estimations the relation between exchange rates and the common factor is contemporaneous and stable during the studied period.Movimientos comunes e idiosincráticos en las tasas de cambio de América Latina Enfoque En este documento se presenta un enfoque que permite diferenciar, tanto teóricamente como empíricamente, los movimientos comunes e idiosincráticos de las tasas de cambio de cinco economías latinoamericanas: Brasil, Chile, Colombia, México y Perú. Para la parte empírica estimamos un factor común regional usando un modelo de factores dinámicos. Esta metodología se aplica a datos de baja y alta frecuencia. Contribución La aproximación propuesta se enmarca en la literatura sobre los determinantes de la tasa de cambio y presenta dos contribuciones principales. En primer lugar, se presenta evidencia que el factor común regional de las tasas de cambio ha sido un determinante importante y estable para explicar la dinámica de la tasa de cambio. En segundo lugar, se presenta un modelo teórico y empírico sencillo que permite distinguir los movimientos regionales e idiosincráticos durante episodios de estrés como la crisis financiera global de 2008-2009, el choque de materias primas a mediados de la década pasada y la crisis sanitaria producto del COVID-19. Resultados Las estimaciones de modelos econométricos con datos de baja y alta frecuencia señalan que el factor común es significativo en todas las estimaciones y es relevante para explicar el movimiento de las tasas de cambio en Brasil, Chile, Colombia, México y Perú. El ajuste y evaluación de dichos modelos también es mejor que el que usualmente se encuentra en modelos de tasa de cambio. En las estimaciones, la relación entre las tasas de cambio y el factor común es contemporánea y estable durante el periodo de estudio analizado. Frase destacada: Los resultados resaltan la posibilidad de distinguir los factores comunes y los fundamentales propios de cada moneda como una herramienta útil para entender la dinámica de la tasa de cambio y evaluar posibles desalineamientos

    Modelación de la Volatilidad de los CDS a Diferentes Plazos: Una Aplicación para Países Latinoamericanos

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    Evaluar la dinámica de las medidas de prima de riesgo y su relación con los fundamentales macroeconómicos es importante tanto para quienes implementan las políticas macroeconómicas como para los participantes del mercado. En este documento se analizan los principales determinantes de los CDS para economías de Latinoamérica a diferentes plazos, enfocándose en su volatilidad. Empleando un modelo GARCH por componentes, se realiza una descomposición de la volatilidad de los CDS a diferentes plazos entre un componente permanente y transitorio. En los resultados se encuentra que el componente permanente de la volatilidad de los CDS en todos los plazos fue mayor y más persistente durante la crisis financiera global que durante el episodio más reciente relacionado con el choque del COVID-19.Assessing the dynamics of risk premium measures and its relationship with macroeconomic fundamentals is important for both macroeconomic policymakers and market practitioners. This paper analyzes the main determinants of CDS in Latin-America at different tenures, focusing on their volatility. Using a component GARCH model, we decompose volatility between permanent and transitory components. We find that the permanent component of CDS volatility in all tenors was higher and more persistent in the global financial crisis than during the recent COVID-19 shock

    Acoustic transmission through perforated plates with fractal subwavelength apertures

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    The acoustic transmission response of plates perforated with fractal subwavelength holes array is studied. The Sierpinski Carpet pattern is used as fractal geometry. Ultrasound transmission spectra show that each iterative Sierpinski Carpet has the characteristic peaks and dips of the lattice constant of each array that formed the pattern. The angular dependency of the transmission coefficients shows a complex interplay between Fabry-Perot resonances, Wood anomaly minima and Lamb modes. (c) 2013 Elsevier Ltd. All rights reserved.This work has been supported by the Spanish MICINN (MAT2010-16879) and Universitat Politecnica de Valencia (PAID-06-10-1839).Gómez Lozano, V.; Uris Martínez, A.; Candelas Valiente, P.; Belmar Ibáñez, F. (2013). Acoustic transmission through perforated plates with fractal subwavelength apertures. Solid State Communications. 165:11-14. https://doi.org/10.1016/j.ssc.2013.04.012S111416

    Hadronic aspects of exotic baryons

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    In this talk I look into three different topics, addressing first the possibility that the Θ+\Theta^+ is a bound state of KπNK \pi N, exploiting the results of this study to find out the contribution of two meson and one baryon components in the baryon antidecuplet and in the third place I present results on a new resonant exotic baryonic state which appears as dynamically generated by the Weinberg Tomozawa ΔK\Delta K interaction.Comment: Talk at the International Workshop PENTAQUARK0

    On the determination of Θ+\Theta^+ quantum numbers and other topics of exotic baryons

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    In this talk I look into three different topics, addressing first a method to determine the quantum numbers of the Θ+\Theta^+, then exploiting the possibility that the Θ+\Theta^+ is a bound state of KπNK \pi N and in the third place I present results on a new resonant exotic baryonic state which appears as dynamically generated by the Weinberg Tomozawa ΔK\Delta K interaction.Comment: 9 pags. Talk in the NSTAR04 Workshop, Grenoble, march 200

    The Artful Eye: Exploring Visual Engagement with Artworks in Different Contexts

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    Artworks are increasingly experienced in non-traditional platforms, from digital collections on museum websites to virtual gallery tours, making it important to investigate the context-dependent and context-independent aspects of aesthetic experience. While some studies have shown that artworks in the museum elicit a higher visual engagement than when presented on a screen, others reported divergent findings. This thesis suggests that such discrepancies may be due to the interaction between the artwork's physical and contextual characteristics and investigates how diverse aspects of viewing behaviour change between the museum, on-screen laboratory, and virtual gallery laboratory contexts. Fifteen paintings by different Australian artists from the Art Gallery of New South Wales (AGNSW) were included as stimuli for the studies in this thesis. Mobile and screen-based eye movement recordings were used to index visual engagement (number of fixations, total and average fixation duration) with artworks across the three different contexts. Our first study (Chapter 2) compared the visual engagement of museum visitors in the AGNSW to that of participants looking at their digital reproductions in laboratory. We focused on how aspects of viewing behaviour, including viewing distance in the gallery condition and eye gaze measures such as fixation count, total fixation duration and average fixation duration are affected by the artworks’ physical characteristics, including size and image statistics properties such as Fourier amplitude spectrum, fractal dimension and entropy. The effects of these factors on visual engagement were then explored in a virtual gallery replica of the exhibition (Chapter 3). In a virtual gallery context, we also tested the impact of two additional context-dependent factors: the curatorial arrangement and further manipulations of the relative size of the paintings. Overall, the results show significant differences in viewing behaviour across different contexts, but also that the effects of presentation contexts are modulated by the artworks’ physical characteristics. In the final two studies, the thesis explores the effect of mere exposure on viewing behaviour in different contexts (Chapter 4) and the spatial and temporal image statistics of fixated compared to non-fixated regions of artworks in both the museum and on- screen viewing contexts (Chapter 5). The results show that visual engagement in the museum, but not on-screen, is enhanced by previous exposure to digital reproductions of artworks. Finally, Chapter 5 demonstrates that fixated and randomly selected regions differed in both spatial and temporal image statistics with more pronounced differences in the on-screen viewing condition. In sum, the thesis demonstrates that a combination of context-dependent variables (e.g., navigation, curatorial setting and relative size) and the low-level properties (e.g., fractal dimension, amplitude spectrum, entropy) of artworks influence visual engagement

    Endotelina : un nuevo péptido regulador cardiovascular

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    Tesis Univ. Complutense de MadridFac. de MedicinaTRUEpu

    Repercusiones del Programa de Intervención para Desarrollar la Responsabilidad Personal y Social de Hellison sobre los comportamientos de fair-play y el auto-control

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    Este estudio examinó las repercusiones del Programa de Intervención para Desarrollar la Responsabilidad Personal y Social de Hellison (1995) sobre los comportamientos de fair-play y el auto-control en jóvenes escolares. La muestra estuvo formada por estudiantes de dos colegios públicos (N= 142), de una media de edad de 12.7 años (grupo experimental= 72, grupo control= 70). Al grupo experimental se aplicó el Programa de Intervención en diez sesiones de iniciación al fútbol-sala de una hora de duración. Los resultados mostraron, en el grupo experimental, mejoras significativas en la retroalimentación personal, el retraso de la recompensa, el auto-control criterial, el auto-control del proceso, las opiniones relacionadas con la diversión, y las conductas deportivas. Se observaron disminuciones en las variables relacionadas con el juego duro, las faltas de contacto y las conductas antideportivas. En el grupo control no se encontraron cambios significativos

    Detección de mastitis subclínica en vacas lecheras usando modelos alométricos y algoritmos de inteligencia artificial, San Carlos, Costa Rica

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    Tesis (Licenciatura en Ingeniería en Agronomía). Instituto Tecnológico de Costa Rica. Escuela de Agronomía, 2019.A mastitis detection trial was performed at Ganadera La Uno S.A, in la Marina de San Carlos (CRTM05 coordinates 458742.53 E y 1147645.93 N). The aim of this investigation was to develop and compare mastitis detection models based on alometric models and artificial intelligence algorithms. Data was colected from an automated milking system equipped with online measuarements. Diseased cows were defined either as those which recorded somatic cell count (CCS) greater than 200 000 cs/ml or a those with a somatic cell count score (SCCS) of four or greater. The best response variable in was SCCS due to its compliance with the normal distribution and adequate fit in the models. Electric conductivity (CE), milk yield (PL), days in milk (DEL), age (ED), reproductive condition (ER) and lactation number (NP) were used as predictive variables of SCCS. Alometric models were linear or linearized and showed R2 values lower than 0.32. Moreover, predictive value of these models was inadequate in terms of sensibility (SEN) and specificity (ESP), since the specificity was 55% when the sensitivity was fixed at 80% and the area under the ROC curve of these models approached 75%. Results do not support the use of a Naïve Bayes classification algorithm to predict mastitis because sensitivity and specificity values were inadequate. The best predictive model was a linear regression model combined with machine learning, with values of ESP and ROC area curve of 84.3 and 92.1% respectively (80% fixed sensibility). This work presents evidence of the potential value of artificial intelligence models in mastitis detection in dairy farms
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