La raza sayaguesa base de la marca silomaña. Actualidad y posibilidades

La utilización de los pastos de la montaña de León unido a una raza autóctona, la raza sayaguesa, para la obtención de un producto de calidad y diferenciado como es el buey. Nos ha permitido obtener un producto de unas características hasta ahora desconocidas, con un perfil de ácidos grasos mono y poliinsaturados, y unas características físico-químicas que hacen que nuestro producto puede considerarse como un “ALIMENTO FUNCIONAL”

From circular paths to elliptic orbits: A geometric approach to Kepler's motion

The hodograph, i.e. the path traced by a body in velocity space, was introduced by Hamilton in 1846 as an alternative for studying certain dynamical problems. The hodograph of the Kepler problem was then investigated and shown to be a circle, it was next used to investigate some other properties of the motion. We here propose a new method for tracing the hodograph and the corresponding configuration space orbit in Kepler's problem starting from the initial conditions given and trying to use no more than the methods of synthetic geometry in a sort of Newtonian approach. All of our geometric constructions require straight edge and compass only.Comment: 9 pages, 4 figure

Modelling Long-Term Urban Temperatures with Less Training Data: A Comparative Study Using Neural Networks in the City of Madrid

In the last decades, urban climate researchers have highlighted the need for a reliable provision of meteorological data in the local urban context. Several efforts have been made in this direction using Artificial Neural Networks (ANN), demonstrating that they are an accurate alternative to numerical approaches when modelling large time series. However, existing approaches are varied, and it is unclear how much data are needed to train them. This study explores whether the need for training data can be reduced without overly compromising model accuracy, and if model reliability can be increased by selecting the UHI intensity as the main model output instead of air temperature. These two approaches were compared using a common ANN configuration and under different data availability scenarios. Results show that reducing the training dataset from 12 to 9 or even 6 months would still produce reliable results, particularly if the UHI intensity is used. The latter proved to be more effective than the temperature approach under most training scenarios, with an average RMSE improvement of 16.4% when using only 3 months of data. These findings have important implications for urban climate research as they can potentially reduce the duration and cost of field measurement campaigns

Metal-Insulator Transition in the Two-Dimensional Hubbard Model at Half-Filling with Lifetime Effects within the Moment Approach

We explore the effect of the imaginary part of the self-energy, $Im\Sigma(\vec{k},\omega)$, having a single pole, $\Omega(\vec{k},\omega)$, with spectral weight, $\alpha(\vec{k})$, and quasi-particle lifetime, $\Gamma(\vec{k})$, on the density of states. We solve the set of parameters, $\Omega(\vec{k},\omega$), $\alpha(\vec{k})$, and $\Gamma(\vec{k})$ by means of the moment approach (exact sum rules) of Nolting. Our choice for $\Sigma(k,\omega)$, satisfies the Kramers - Kronig relationship automatically. Due to our choice of the self - energy, the system is not a Fermi liquid for any value of the interaction, a result which is also true in the moment approach of Nolting without lifetime effects. By increasing the value of the local interaction, $U/W$, at half-filling ($\rho = 1/2$), we go from a paramagnetic metal to a paramagnetic insulator, (Mott metal - insulator transition ($MMIT$)) for values of $U/W$ of the order of $U/W \geq 1$ ($W$ is the band width) which is in agreement with numerical results for finite lattices and for infinity dimensions ($D = \infty$). These results settle down the main weakness of the spherical approximation of Nolting: a finite gap for any finite value of the interaction, i.e., an insulator for any finite value of $U/W$. Lifetime effects are absolutely indispensable. Our scheme works better than the one of improving the narrowing band factor, $B(\vec{k})$, beyond the spherical approximation of Nolting.Comment: 5 pages and 5 ps figures (included

Hyperbolicity of the Kidder-Scheel-Teukolsky formulation of Einstein's equations coupled to a modified Bona-Masso slicing condition

We show that the Kidder-Scheel-Teukolsky family of hyperbolic formulations of the 3+1 evolution equations of general relativity remains hyperbolic when coupled to a recently proposed modified version of the Bona-Masso slicing condition.Comment: 4 pages. Several changes. Main corrections are in eqs. 4.9 and 4.1

Utilización de un método in vitro para evaluar la toxicidad de chaya, una planta nutritiva utilizada en medicina tradicional para la disminución del colesterol.

La “chaya” (Cnidoscolus chayamansa y Cnidoscolus aconitifolius) pertenece a la familia de las Euphorbiacea, es conocida como árbol de espinaca y ha sido cultivada desde la época prehispánica, se usaba como hasta hoy como planta comestible, medicinal y ornamental por más de 10 grupos Mayas y también por otros grupos Mexicanos y Mesoamericanos. Normalmente se encuentra cultivada en huertos familiares o jardines, la hoja algunas veces el pecíolo y los brotes son cosechadas y cocidas para varios tipos de guisados siendo una fuente importante de proteínas, beta caroteno, vitaminas, ácido ascórbico, calcio y hierro o son utilizadas con fines medicinales destacando su propiedad como hipocolesterolémico. El propósito del presente trabajo fue la evaluación preliminar de la toxicidad de tres extractos obtenidos de las hojas de C. chayamansa en un modelo in vitro, utilizando Artemia salina

Desarrollo de aderezos con harina de amaranto y harina de quinua.

El uso de aderezos es muy amplio debido al sabor que aportan a nuestras comidas, dentro de los ingredientes que se usan para su elaboración se encuentra la yema de huevo. El inconveniente es que posee gran cantidad de colesterol, un huevo contiene aproximadamente 200 mg de colesterol, que casi cumple con el límite de la ingesta alimentaria establecido por la American Heart Association de <300mg/día (Sun et al., 2011). El objetivo de este trabajo fue desarrollar aderezos empleando harina de quinua y amaranto como emulsificantes, sustituyendo a la yema de huevo. Se elaboraron los aderezos empleando: sal, vinagre, azúcar y agua; como emulsificantes: yema de huevo, harina de amaranto y harina de quinua. Las formulaciones se presentan en la Tabla I. Se midieron las curvas de flujo y el tamaño de partícula de los aderezos. Las tasas de cremado para los aderezos ADCtrl (Aderezo Control), AD Quinoa (Aderezo Quinoa) y AD Amaranto (Aderezo Amaranto) fueron: 3.67 x 10-7, 1.33 x 10-7 y 4.67 x 10-7. Todos los aderezos presentaron n < 1 (índice de fujo), siendo todos pseudoplásticos. Es posible elaborar aderezos estables empleando la harina de quinua y amaranto