Magnetorotational Instability in Core-Collapse Supernovae

We discuss the relevance of the magnetorotational instability (MRI) in core-collapse supernovae (CCSNe). Our recent numerical studies show that in CCSNe, the MRI is terminated by parasitic instabilities of the Kelvin-Helmholtz type. To determine whether the MRI can amplify initially weak magnetic fields to dynamically relevant strengths in CCSNe, we performed three-dimensional simulations of a region close to the surface of a differentially rotating proto-neutron star in non-ideal magnetohydrodynamics with two different numerical codes. We find that under the conditions prevailing in proto-neutron stars, the MRI can amplify the magnetic field by (only) one order of magnitude. This severely limits the role of MRI channel modes as an agent amplifying the magnetic field in proto-neutron stars starting from small seed fields.Comment: Proceedings in Acta Physica Polonica B, Proceedings Supplement, Vol. 10, No. 2, p.361, 4 pages, 1 figur

Replacement of fish meal by a mixture of vegetal proteins and vegetal proteins combined with prebiotics in Gilt-head sea bream diets (Sparus aurata)

Three diets have been formulated to evaluate the effect of prebiotec (dry hydrolyzed intestinal mucosa) by supplementation in plant protein diets of gilt-head sea bream of 273g (average initial weight) for 60 days. The diets manufactured to be isonitrogenous (47% crude Protein, CP) and isolipidic (17% crude Lipid, CL) , two diets of them with total replacement of fish meal by a mixture of vegetable proteins, with and without prebiotec 0% Fish meal FM0 & 0% fish meal plus prebiotec FM0 + P. The third diet as the unique protein source 100% fish meal FM100. The growth, nutritional, biometric and histological parameters have been determined at the end of trial, fish reached weights 284, 303 and 407g in the FM0, FM0+P, and FM100 respectively. A statistical differences were observed between FM100 and other two (FM0 & FM0+P) diets in specific growth rate (SGR), Daily feeding rate (DFR), feed conversion ratio (FCR) and protein efficiency ratio (PER). Biometric indices show significant differences between FM100 and other two (FM0 & FM0+P) in condition factor (CF), viscerosomatic index (VSI), hepatosomatic index (HSI) and meat index (MI) as they were significantly decreasing by increasing FM replacement percent, also there were significant differences between FM100 and FM0 in Headless index (HI). The index of the non-edible parts (NEPI) was significantly higher in (FM0 & FM100) than FM100 while there were no significant differences between all diets in mesenteric fat index (MFI). Moreover, body composition was affected by the substitution with vegetable proteins, there was a decrease in water, protein and ash content and an increase of lipid and energy content from the start to the end of the trial. At the end of trial fat content was higher in the gilt-head sea bream fed FM100 diet followed by FM0+P and the least amount of fat was in gilt-head sea bream fed with feed FM0 when there were no significant differences in energy content in all groups. Protein and ash content also presents significant differences between the gilt-head sea bream that fed with feed FM0 and the gilt-head sea bream that fed other diets (FM0+P, FM100) where they were higher in FM0. The histological parameters of gut and liver not affected by different experimental diets. The morphological evaluation showed all fish in intermediate case except in FM0+P there was a severe fat accumulation within the hepatocytes. . The supplementation of prebiotec (dry hydrolyzed intestinal mucosa) was not useful contrary to the results of Tortosa, (2004) may be result to the parasite infections during the trial. The results of the current study showed that the immune role of the prebiotec was not enough to face the parasite infection and it is not recommended to use as a supplementation in vegetable meals in case of presence of parasites risk

Function of two variables and sequences eventually periodic.

I present an algorithm that defines a function generator of sequences eventually periodic, with eligible cycle values and starting with any integer

Función de dos variables y sucesiones numéricas eventualmente periódicas.

Presento un algoritmo que define una función generadora de secuencias eventualmente periódicas, con los valores del ciclo elegibles y empezadas con cualquier número entero

MY PROOF OF THE COLLATZ CONJECTURE

In this paper, the properties of the digital root of numbers are analyzed and a possible connection with the sequences of the Collatz Conjecture is sought. p { margin-bottom: 0.25cm; line-height: 115%; background: transparent

A Model for developing an academic activity index for higher education instructors based on composite indicators

The assessment of the teacher performance is a subject of criticism due to the lack of a well-establish methodology. This study develops an overall score to measure the dimensions that encompass the academic activities. To that end, a Benefit-of-the-doubt model is proposed. The advantage of this technique is the flexibility in the weights, so that the model selects for each teacher the most favourable set of weights. Furthermore, the paper proposes the barycentric coordinate system as a method to classify the teachers in clusters depending on their contribution to the dimensions. A specific pie chart has been proposed as an efficient way to report the contribution of the teachers to the dimensions and the overall teacher performance

MI DEMOSTRACION DE LA CONJETURA DE COLLATZ

En este escrito, se analizan las propiedades de la raíz digital de los números y se busca una posible conexión con las secuencias de la Conjetura de Collatz