How Far Do Shocks Move Across Borders? Examining Volatility Transmission in Major Agricultural Futures Markets

This paper examines the level of interdependence and volatility transmission in global agricultural futures markets. We follow a multivariate GARCH approach to explore the dynamics and cross-dynamics of volatility across major exchanges of corn, wheat, and soybeans between the United States, Europe, and Asia. We account for the potential bias that may arise when considering exchanges with different closing times. The results indicate that agricultural markets are highly interrelated and there are both own- and cross- volatility spillovers and dependence among most of the exchanges. The results also show the major role Chicago plays in terms of spillover effects over the other markets, particularly for corn and wheat. Additionally, the level of interdependence between exchanges has only increased in recent years for some of the commodities.Volatility transmission, agricultural commodities, futures markets, Multivariate GARCH.

A Radial Velocity Study of the Intermediate Polar EX Hydrae

A study on the intermediate polar EX Hya is presented, based on simultaneous photometry and high dispersion spectroscopic observations, during four consecutive nights. The strong photometric modulation related to with the 67-min spin period of the primary star is clearly present, as well as the narrow eclipses associated to the orbital modulation. Since our eclipse timings have been obtained almost 91,000 cycles since the last reported observations, we present new linear ephemeris, although we cannot rule out a sinusoidal variation suggested by previous authors. The system mainly shows double-peaked H$\alpha$, H$\beta$ and HeI $\lambda$5876 \AA emission lines. From the profile of the H$\alpha$ line, we find two components; one with a steep rise and velocities not larger than $\sim$1000 km s$^{-1}$ and another broader component extending up to $\sim$2000 km s$^{-1}$, which we interpret as coming mainly from the inner disc. A strong and variable hotspot is found and a stream-like structure is seen at times. We show that the best solution correspond to $K_1 = 58 \pm 5$ km s$^{-1}$ from H$\alpha$, from the two emission components, which are both in phase with the orbital modulation. We remark on a peculiar effect in the radial velocity curve around phase zero, which could be interpreted as a Rositter-MacLaughlin-like effect, which has been taken into account before deriving $K_1$. This value is compatible with the values found in high-resolution both in the ultraviolet and X-ray. We find: $M_{1} = 0.78 \pm 0.03$ M$_{\odot}$, $M_{2} = 0.10 \pm 0.02$ M$_{\odot}$ and $a = 0.67 \pm 0.01$ R$_{\odot}$. Doppler Tomography has been applied, to construct six Doppler tomograms for single orbital cycles spanning the four days of observations to support our conclusions. Our results indicate that EX Hya has a well formed disc and that the magnetosphere should extend only to about $3.75\,R_{\rm{WD}}$.Comment: 16 pages, 14 figures, accepted for publication in MNRA

Adverse events of ERCP at San José Hospital of Bogotá (Colombia)

Endoscopic retrograde cholangiopancreatography (ERCP) has become the preferred treatment method for hepatobiliary and pancreatic disease. Despite technological progress this technique continues to account for the greatest morbidity and mortality caused by digestive endoscopic procedures. ERCP carries a risk of pancreatitis, perforation, hemorrhage, cholangitis and cardiopulmonary events occurring in upto 10% of patients in referral centers, implying a mortality of up to 1%, not including therapeutic failures or the need for re-intervention. A greater mortality rate has been demonstrated in prospective studies rather than in retrospective studies, but overall, the number of complications described in the literature is much lower than the number of complications that actually occur. A descriptive prospective study was conducted at San José Hospital from April 1, 2006 to April 30, 2007 in patients who underwent an ERCP and had a 1-month follow-up. A total of 381 patients were included; 9 (2.3%) were excluded, and of the remaining 372 there was an overall success in 79.6% of cases, 8.3% had a second intervention, 7.6% developed complications (pancreatitis, perforation, hemorrhage, cholangitis, pain, intolerance to sedatives, and cardiopulmonary events), and 4.3% were failed ERCP studies. The mortality rate of the ERCP procedure was 0.8%. ERCP-related complications were determined at a teaching center, and this suggests the need to implement centers of excellence in order to improve the efficacy of the procedure

Convection and cracking stability of spheres in General Relativity

In the present paper we consider convection and cracking instabilities as well as their interplay. We develop a simple criterion to identify equations of state unstable to convection, and explore the influence of buoyancy on cracking (or overturning) for isotropic and anisotropic relativistic spheres. We show that a density profile $\rho(r)$, monotonous, decreasing and concave , i.e. $\rho' < 0$ and $\rho'' < 0$, will be stable against convection, if the radial sound velocity monotonically decreases outward. We also studied the cracking instability scenarios and found that isotropic models can be unstable, when the reaction of the pressure gradient is neglected, i.e. $\delta \mathcal{R}_p = 0$; but if it is considered, the instabilities may vanish and this result is valid, for both isotropic and anisotropic matter distributions.Comment: 16 pages, 5 figure

Oxidation of the borohydride Ion at silver nanoparticles on a glassy carbon electrode (GCE) using pulsed potential techniques

Direct oxidation borohydride fuel cells are very attractive energy conversion devices. Silver has been reported as one of the few materials which can catalyze an 8-electron oxidation. Potential step amperometric pulse techniques to synthesize nanostructured silver material on flat glassy carbon electrodes is reported and significant differences with bulk silver deposit have been observed. The oxidation of borohydride ion on the silver particles occurs at -0.025 V vs. SCE and the potential decreases towards negative values at longer cycle times. The oxidation current also decreases with the number of cycles, suggesting that the silver active sites become partially blocked by oxidation products of borohydride. The electroactive area per unit electrode area of silver was relatively low for particles deposited using potential step amperometric techniques on glassy carbon (0.002 cm2 per cm-2) compared with the area found at a polycrystalline silver electrode (0.103 cm2 per cm-2

Inclusion of macroalgae meal (Macrocystis pyrifera) as feed ingredient for rainbow trout (Oncorhynchus mykiss): Effect on flesh fatty acid composition

The use of macroalgae as an additional component in animal feeding has been studied. However, information on how it could influence muscle composition of fish body is scarce. This study evaluates four diets with different macroalgae inclusion levels (0%, 1.5%, 3% and 6%) to test the effect on body fatty acid composition of rainbow trout. Tanks with a volume of 600 L were stocked with 60.6 ± 7.9 g fish at a density of 45 individuals tank-1 and fed for 124 days. At the end of the experiment there were not significant differences (P&lt;0.05) in muscle proximate composition among fish fed the different treatments. However, it was determined that inclusion of 3% and 6% of macroalgae meal resulted in a significant increase (P&lt;0.05) of polyunsaturated fatty acids (PUFAs) in muscle. In summary, macroalgae meal in rainbow trout diets do not enhance the quantity of protein and lipid contents at muscle level but an addition of 3-6% might contribute to increase the level of PUFAs, specially EPA, DHA and LIN. Thus, use of macroalgae meal might help to increase lipid quality content in the final product due the beneficial effects of PUFAs for human health

Las implicaciones de la reforma energética para Tabasco

Esta investigación tiene como finalidad aportar elementos de análisis y discusión para la reflexión sobre la temática relacionada con los aspectos socioculturales que genera el petróleo en una entidad petrolera como Tabasco. Así como identificar algunas de las implicaciones positivas o negativas para la economía local y analizar los aciertos y desaciertos que se han generado a partir de la aprobación de reforma energética en el año 2013. En esta entidad, la economía del estado había sido desde el siglo pasado una economía de vocación natural, sin embargo, la explotación intensiva de hidrocarburos desde los años 80s derivado del Boom petrolero trajo como consecuencia la transformación hacia una economía petrolizada. La economía tradicional basada en el sector primario (agricultura, ganadería, pesca y las agroindustrias) pasó a ser una economía altamente petrolizada caracterizada por un proceso de migración del campo hacia la ciudad capital así como de otras entidades del país. Hoy después de 40 años de explotación intensiva de la actividad petrolera los tabasqueños seguimos observando el nulo crecimiento en los sectores primario y secundario en contraste con la evolución del sector terciario gigante. Con las expectativas de la reforma energética aprobada en 2013 se espera que se genere un nuevo "mini" boom petrolero con las consecuencias positivas o negativas para Tabasco que aquí se plantean. El método utilizado en esta investigación es analítico y descriptivo y la metodología es mayormente de tipo cuantitativa mediante un modelo deductivo con el criterio que va de lo general a lo particula

LAS REFORMAS ESTRUCTURALES Y SU EFECTO EN EL DESARROLLO REGIONAL

El presente trabajo tiene la finalidad de analizar los efectos de las principales reformas estructurales aprobadas en el año 2013 e implementadas en nuestro país y sus respectivos efectos en los sectores productivos de las regiones productoras de petróleo. En particular se trata de realizar un análisis de la reforma realizada al sector petrolero para revisar los indicadores económicos que están frenando el desarrollo regional. Las desigualdades sociales en las regiones altamente petrolizadas como Tabasco, Campeche, y Veracruz, se ven reflejadas en los altos indicadores de rezago social, pobreza y marginación de su población que junto con la falta de empleos y oportunidades de trabajo están impactando en las principales actividades económicas de estas entidades. Por ello, consideramos necesario implementar acciones y estrategias regionales que atiendan de manera integral esta problemática de falta de desarrollo económico para mejorar la calidad de vida de sus habitantes de los estados afectados. Las reformas estructurales sobre todo la petrolera han provocado el desplome de la economía de estas regiones petroleras que hoy padecen las peores crisis. Se identificó la problemática mediante la aplicación de un modelo deductivo con el criterio que va de lo general a lo particular. La metodología propuesta para el desarrollo de este trabajo es de tipo cuantitativa y consiste en realizar un análisis de la literatura relacionada con la reforma energética promovida por el Ejecutivo Federal, la consulta de libros, estadísticas y datos históricos de la actividad petrolera en México. Se utilizaron diversas técnicas de recolección de información como la revisión documental de revistas especializadas y medios electrónicos. El método para el desarrollo de la investigación es analítico y descriptivo y la metodología utilizada es de tipo cuantitativa

Automotive Control Catalyzer to Synthetize CaCO3 from Residual Co2 Embedded Control System

La contaminación generada por el sector automotriz es un problema de medio ambiente por el que sectores gubernamentales y privados han tomado acciones para contrarrestarla. Uno de esos esfuerzos procura de proveer una solución para la emisión de gases de producidos de diferentes sistemas de combustión. El objetivo del presente proyecto es diseñar un sistema de alta calidad y confiable, capaz de transformar una cantidad considerable de los gases emitidos en nuevo combustible antes de ser liberados de vuelta al entorno. El módulo de control fue desarrollado considerando los requerimientos demandados por la industria automotriz. El controlador fue basado sobre la arquitectura AUTOSAR, este también incluyó el protocolo de comunicación estándar CAN 2.0 desempeñado con el microcontrolador validado como grado 2 por el Consejo de Electrónica Automotriz, y el sensor SHT11 usado fue certificado contra RoHS. La arquitectura de software cumple con la complejidad inherente de las especificaciones de AUTOSAR, por consiguiente, diferentes técnicas fueron requeridas para su solución, incluyendo la definición, diagramas de límites, especificación de requerimientos, interfaces de software e interacción de módulos. Una vez que los requerimientos fueron conocidos, el código fue implementado. Como resultado, este módulo puede ser categorizado como un producto de grado automotriz que puede ser introducido en el mercado automotriz.The pollution generated by the automotive sector has been an environmental issue in the latest years, and nowadays, different governmental and private sectors have taken actions on this matter. One of these efforts tries to provide a solution for contaminating gas emissions produced from different fuel combustion systems. The aim of the present project is to design a reliable and high-quality system that senses the environmental temperature, relative humidity, and calculates the dew point to control a catalyzer capable of transforming a considerable amount of exhaust gases into a new fuel component before they are released back into the environment. The control module was developed considering the requirements demanded by the automotive industry. The controller was based on an AUTOSAR architecture, it also included the standard CAN 2.0 communication protocol performed within the microcontroller validated as grade 2 by the Automotive Electronics Council, and the SHT11 sensor used was certified against RoHS. Equally important, the software architecture complied with the complexity inherent in AUTOSAR specifications. Therefore, different techniques were required for its solution, including, boundary diagram, requirement specifications, software interface, and module interaction definitions. Once these requirements where met, the code was implemented. As a result, this module could be categorized as an automotive-grade product that can be introduced in the automotive market.Consejo Nacional de Ciencia y Tecnologí