JET Formation in Solar Atmosphere Due to Magnetic Reconnection

Using numerical simulations, we show that jets with features of type II spicules and cool coronal jets corresponding to temperatures of 104 K can be formed as a result of magnetic reconnection in a scenario with magnetic resistivity. For this, we model the low chromosphere–corona region using the C7 equilibrium solar atmosphere model, assuming that resistive MHD rules the dynamics of the plasma. The magnetic field configurations we analyze correspond to two neighboring loops with opposite polarity. The formation of a highspeed and sharp structure depends on the separation of the loops’ feet. We analyze the cases where the magnetic field strength of the two loops is equal and different. In the first case, with a symmetric configuration the jets rise vertically, whereas in an asymmetric configuration the structure shows an inclination. With a number of simulations carried out under a 2.5D approach, we explore various properties of the excited jets, namely, inclination, lifetime, and velocity. The parameter space involves a magnetic field strength between 20 and 40 G, and the resistivity is assumed to be uniform with a constant value of the order 10-2W · m

Un método de regularización de mallas de elementos finitos en modelos tridimensionales sólidos

La importancia que tiene en el análisis por elementos finitos la obtención de forma automática de una malla de calidad contrastada ha originado que en los últimos años se haya dedicado un gran esfuerzo al estudio del mallado adaptivo, de modo que se pueda corregir una malla a partir de la cuantificación de alguna magnitud representativa de la calidad de la misma, siguiendo algún esquema de refinado de malla. Lógicamente, los resultados de este proceso serán tanto más válidos cuanto mayor sea la calidad de la malla de partida. Este artículo expone un método de corrección de mallas de elementos finitos a partir de la modificación de las coordenadas de determinados nudos del mallado con el fin de obtener elementos con una relación de aspecto tan próxima a la unidad como sea posible. El método es completamente automático y aplicable a cualquier malla de elementos finitos correspondiente a un modelo 3D sólido, si bien su adaptación a otro tipo de modelos (por ejemplo, superficies o modelos planos) es imediata. El resultado es la obtención de una malla de mejor calidad, que puede utilizarse ventajosamente como punto de partida en un esquema de mallado adaptivo, dando lugar a resultados más aceptables.The method here proposed for the correction of finite-element meshes is based on the modification of the coordinates of certain mesh nodes, the aim being to derive elements with an aspect relation as close as possible to unity. This entirely automatic method can be applied to any finite-element mesh corresponding to a 3-D solid model, while furthermore it is quickly adaptable to various other types, including plane models of surfaces. The outcome in each case is a mesh of higher quality, a sound basis for a self-adaptive mesh scheme and a promise of better results.Peer Reviewe

Un método de regularización de mallas de elementos finitos en modelos tridimensionales sólidos

La importancia que tiene en el análisis por elementos finitos la obtención de forma automática de una malla de calidad contrastada ha originado que en los últimos años se haya dedicado un gran esfuerzo al estudio del mallado adaptivo, de modo que se pueda corregir una malla a partir de la cuantificación de alguna magnitud representativa de la calidad de la misma, siguiendo algún esquema de refinado de malla. Lógicamente, los resultados de este proceso serán tanto más válidos cuanto mayor sea la calidad de la malla de partida. Este artículo expone un método de corrección de mallas de elementos finitos a partir de la modificación de las coordenadas de determinados nudos del mallado con el fin de obtener elementos con una relación de aspecto tan próxima a la unidad como sea posible. El método es completamente automático y aplicable a cualquier malla de elementos finitos correspondiente a un modelo 3D sólido, si bien su adaptación a otro tipo de modelos (por ejemplo, superficies o modelos planos) es imediata. El resultado es la obtención de una malla de mejor calidad, que puede utilizarse ventajosamente como punto de partida en un esquema de mallado adaptivo, dando lugar a resultados más aceptables.The method here proposed for the correction of finite-element meshes is based on the modification of the coordinates of certain mesh nodes, the aim being to derive elements with an aspect relation as close as possible to unity. This entirely automatic method can be applied to any finite-element mesh corresponding to a 3-D solid model, while furthermore it is quickly adaptable to various other types, including plane models of surfaces. The outcome in each case is a mesh of higher quality, a sound basis for a self-adaptive mesh scheme and a promise of better results.Peer Reviewe

Spicule jets in the solar atmosphere modeled with resistive MHD and thermal conduction

Using numerical simulations, we study the effects of magnetic resistivity and thermal conductivity in the dynamics and properties of solar jets with characteristics of Type II spicules and cool coronal jets. The dynamic evolution of the jets is governed by the resistive MHD equations with thermal conduction along the magnetic field lines on a 2.5D slice. The magnetic field configuration consists of two symmetric neighboring loops with opposite polarity, used to support reconnection and followed by the plasma jet formation. In total, 10 simulations were carried out with different values of resistivity and thermal conductivity that produce jets with different morphological and thermal properties we quantify. We find that an increase in magnetic resistivity does not produce significant effects on the morphology, velocity, and temperature of the jets. However, thermal conductivity affects both temperature and morphology of the jets. In particular, thermal conductivity causes jets to reach greater heights and increases the temperature of the jet-apex. Also, heat flux maps indicate the jet-apex and corona interchange energy more efficiently than the body of the jet. These results could potentially open a new avenue for plasma diagnostics in the Sun's atmosphere

Supplementation with \u3ci\u3eBrosimum alicastrum\u3c/i\u3e Swartz to Pelibuey Sheep Fed Low Quality Rations

The objective of the present study was to assess the influence of supplementing increasing levels of ramón (Brosimum alicastrum) foliage to Pelibuey sheep fed guinea grass (Panicum maximum) hay. Rate and extent of rumen degradation of organic matter (OM) and crude protein (CP) of ramón foliage were high. Dry matter (DM) intake of the diet was increased by the inclusion of ramón foliage. However, rate and extent of digestion of guinea grass was not affected by the ramón foliage. Rate of passage of solid was linearly increased as a result of the inclusion of ramón foliage in the ration. Supply of microbial N to the small intestine was significantly increased by the tree foliage. Ramón foliage is a suitable source of nutrients for ruminant during the dry season in tropical Mexico

A proof of uniqueness of the Gurarii space

We present a short and elementary proof of isometric uniqueness of the Gurarii space.Comment: 6 pages, some improvements incorporate

I. Jet Formation and Evolution due to 3D Magnetic Reconnection

Using simulated data-driven three-dimensional resistive MHD simulations of the solar atmosphere, we show that magnetic reconnection can be responsible of the formation of jets with characteristic of Type II spicules. For this, we numerically model the photosphere-corona region using the C7 equilibrium atmosphere model. The initial magnetic configuration is a 3D potential magnetic field, extrapolated up to the solar corona region from a dynamic realistic simulation of solar photospheric magnetoconvection model which is mimicking quiet-Sun. In this case we consider a uniform and constant value of the magnetic resistivity of 12.56 Ω m. We have found that formation of the jets depends on the Lorentz force, which helps to accelerate the plasma upwards. Analyzing various properties of the jet dynamics, we found that the jet structure shows Doppler shift near to regions with high vorticity. The morphology, upward velocity, covering a range up to 100 km s−1, and life-time of the estructure, bigger than 100 s, are similar to those expected for Type II spicules