MHD Remote Numerical Simulations: Evolution of Coronal Mass Ejections

Coronal mass ejections (CMEs) are solar eruptions into interplanetary space of as much as a few billion tons of plasma, with embedded magnetic fields from the Sun's corona. These perturbations play a very important role in solar--terrestrial relations, in particular in the spaceweather. In this work we present some preliminary results of the software development at the Universidad Nacional Autonoma de Mexico to perform Remote MHD Numerical Simulations. This is done to study the evolution of the CMEs in the interplanetary medium through a Web-based interface and the results are store into a database. The new astrophysical computational tool is called the Mexican Virtual Solar Observatory (MVSO) and is aimed to create theoretical models that may be helpful in the interpretation of observational solar data.Comment: 2 pages, 1 color figure. To appear in Proceedings IAU Symposium No. 259. Cosmic Magnetic Fields: From Planets, to Stars and Galaxies. In pres

About gravitational radiation of semi local strings with non compact internal modes

In a previous work [1], given a putative vortex, it was determined whether it is non abelian or not by studying its radiation channels. The example considered there was a $SU(2)$ gauge model whose internal orientational modes are described by an sphere $S^2$. The non abelian effects presented in this reference were not very pronounced, due to the compactness of this space. In the present work, this analysis is extended for a vortex whose internal space is non compact. This situation may be realised by semi-local supersymmetric vortices [2]-[9]. As the internal space has infinite volume, a largely energetic perturbation may propagate along the object. A specific configuration is presented, when the internal space is the resolved conifold with its Ricci flat metric. The curious feature about it is that it corresponds to a static vortex, that is, the perturbation is only due to the internal modes. Even being static, the emission of gravitational radiation is in the present case of considerable order. This suggest that the presence of slowly moving objects that can emit a large amount of gravitational radiation is a hint of non abelianity.Comment: 14 pages, no figures, some irrelevant constants were set to one and the formulas are less cumbersome. Some additional numerical estimation was include

Neutrino emission and initial evolution of axionic quark nuggets

The axion quark nuggets introduced in \cite{zhitnitsky}-\cite{zhitnitsky13} are a candidate for cold dark matter which, in addition, may be relevant in baryogenesis scenarios. The present work studies their evolution till they enter in the colour superconducting phase. This evolution was already considered in \cite{zhitnitsky5}, where it is concluded that a large chemical potential $\mu$ is induced on the bulk of the object. The baryon number accumulated at the domain wall surrounding the object is taken as predominant in \cite{zhitnitsky5}, and it is suggested that internal and external fluxes are compensated and can be neglected. In the present work, the possibility that the bulk contribution to the baryon number may be relevant at initial stages and that the object may emit a large amount of neutrinos due to quark-antiquark annihilations is taken into account. The outcome is a more violent contraction of the object and, perhaps, a more effective cooling. Therefore, the resulting objects may have a smaller size. Even taking into account these corrections, it is concluded that the cosmological applications of these objects are not spoiled. These applications are discussed along the text.Comment: Accepted in Phys Rev

Exploring cloudy gas accretion as a source of interstellar turbulence in the outskirts of disks

High--resolution 2D--MHD numerical simulations have been carried out to investigate the effects of continuing infall of clumpy gas in extended HI galactic disks. Given a certain accretion rate, the response of the disk depends on its surface gas density and temperature. For Galactic conditions at a galactocentric distance of ~20 kpc, and for mass accretion rates consistent with current empirical and theoretical determinations in the Milky Way, the rain of compact high velocity clouds onto the disk can maintain transonic turbulent motions in the warm phase (~2500 K) of HI. Hence, the HI line width is expected to be ~6.5 km/s for a gas layer at 2500 K, if infall were the only mechanism of driving turbulence. Some statistical properties of the resulting forcing flow are shown in this Letter. The radial dependence of the gas velocity dispersion is also discussed.Comment: 13 pages, 3 figures, accepted for publication in ApJ Letter

Estimation of the Efficiency of Hydraulic Pumps

A sustainable design of water supply systems needs to account operational costs. When pumping is required, the energy consumed by the pumps plays a major part in the operational costs, and the efficiency of the pumps can greatly affect the energy expenses. How to properly estimate the value of pump efficiency is hence of great importance. The aim of this study is to study in depth the efficiency of hydraulic pumps, in relation with the other design variables (flow rate, pumping head, power, etc.). For that, 400 hydraulic pumps were analysed. A strong relationship between the flow rate and the pump efficiency was observed. This relationship was interpolated, and three empiric curves were defined (one for the average maximum and minimum expected value of pump efficiency). These curves can be easily used by designers in order to obtain an estimation of the efficiency of the hydraulic pumps

Oil price effect on sectoral stock returns: A conditional covariance and correlation approach for Mexico

Efecto del precio del petróleo en las rentabilidades de las acciones sectoriales: Un enfoque condicional de covarianza y correlación para MéxicoEste trabajo analiza la relación entre la volatilidad del precio del petróleo y rendimientos bursátiles sectoriales seleccionados en México (Industrial, materiales, financiero y de consumo discrecional) a través de la implementación de un modelo GARCH bivariado tipo VECH Diagonal para estimar sus covarianzas y correlaciones condicionales. El hallazgo más importante es que existe una relación estadística significativa entre los índices sectoriales y las variaciones en el precio del petróleo. Las correlaciones condicionales sugieren que durante la mayor parte del periodo del análisis la relación entre el precio del petróleo y los rendimientos sectoriales es positiva. La recomendación apoyada por los resultados descritos es que los inversionistas deben tomar en cuenta la interacción mencionada para generar coberturas de riesgo más robustas. Dentro de las limitantes de la investigación, se encuentra la escasez de información a nivel sector en el mercado bursátil del país. La aportación original de este estudio radica en el análisis con enfoque sectorial. Los resultados apoyan a la corriente que sugiere que las fluctuaciones en el precio del petróleo tienen un efecto directo en el mercado bursátil.This paper analyzes the relationship between the volatility of oil price and selected sectoral stock returns in Mexico (industrials, materials, financials and consumer discretionary) by implementing a Diagonal VECH-type bivariate GARCH model in order to estimate conditional covariances and correlations. The econometric results suggest that there exists a statistically significant relationship between sector indices, as well as between Mexico’s aggregate stock exchange returns, and variations in oil prices. Conditional correlations suggest that during most of the analyzed period, the relationship between oil price fluctuations and sectoral stock returns is positive. The recommendation, supported by these results, is that investors should take into consideration the interaction between the analyzed variables in order to generate more robust risk-hedge strategies. An important limitation for this work is information availability at sector level in the country. The original contribution of this paper lies mainly in the analysis of the influence of oil prices over sectoral indices of the Mexican Stock Exchange. These results provide more support to the current that suggests that a price increase in oil has a direct spillover effect on stock market performance

AZÚCAR CONTRA OTROS EDULCORANTES: ¿CUÁNTO PAGAS POR CALORÍA?

The choice of a product for consumption depends on its flavor, cost, convenience and nutrient content. The flavor depends to a large extent on the caloric density of a food. The most appetizing foods tend to be those that contain higher amount of calories and are frequently associated to lower prices. The objective of this study was to analyze the price-caloric content relation of consumption products offered in stores in México through dispersion graphs to describe the impact of the new consumption trends in the offer of products to final consumers. It was found that beverages are the most abundant and cheapest sources of calories, so they are more accessible to consumers. The mixture of sugars with sweeteners different than sugar does not present broad differences with the prices of products sweetened solely with sucrose; the most important different in prices took place in products with sweeteners different from sucrose. It is important to analyze the consuption policies, since there is evidence that a light product will not always result in a healthy diet.La elección de un producto de consumo depende de su sabor, costo, conveniencia y contenido nutrimental. El sabor depende en gran medida de la densidad calórica de un alimento. Los alimentos más apetecibles suelen ser aquellos que contienen mayor cantidad de calorías y frecuentemente se encuentran asociados a precios más económicos. El objetivo del presente estudio fue analizar la relación del precio con el contenido calórico de productos ofertados en comercios en México mediante gráficos de dispersión para describir el impacto de las nuevas tendencias de oferta de productos a los consumidores finales. Se encontró que las bebidas son las fuentes calóricas más abundantes y más baratas, por lo que son más accesibles para los consumidores. La mezcla de azúcares con edulcorantes diferentes al azúcar, no presenta amplias diferencias con los precios de productos endulzados únicamente con sacarosa; la diferencia de precios más importante ocurrió en productos con edulcorantes distintos de la sacarosa. Es importante analizar las políticas de consumo, puesto que existe evidencia que un producto light no siempre se reflejará en una alimentación sana

Generalities on Private Equity and Venture Capital Funds: a current review of the industry and its environment in Mexico

Private Equity and Venture Capital Funds have shown an exceptional resilience in Mexico and there are good reasons to think they will experience a strong growth in the coming years, although they still represent a very small portion of the gross domestic investment in comparison with other countries of similar economic development. Nevertheless, it is necessary to implement many important legal and other institutional reforms that have proved to contribute to the successful evolution of this industry before it may be considered a new economic development engine for the country.Capital Privado, Capital Emprendedor, Fondos