Hydrodynamical simulations of massive stars collisions

openSince the detection of gravitational waves traveling through our universe, a new field of astrophysics has opened up, and with it many hypotheses and theoretical predictions have been put to the test. This is the case of the pair-instability mass gap (60 and 120 Msun. Gravitational wave signals have been detected whose primary and secondary black holes fall within the mass range where it was previously thought unthinkable that they could exist as a product of stellar evolution. Different mechanisms could explain these observations, among which the gravitational collapse of a particular type of remnant from a collision between two predecessor stars stands out. Multiple studies support this hypothesis, however, it is necessary to determine the incidence of the collision parameters on the main characteristics of the post-coalescence star, especially to corroborate that its final mass and chemical composition made it a suitable remnant to produce these special black holes. To achieve this goal, the hydrodynamic simulations of stellar collisions are a perfect tool. In this thesis, we have analyzed a set of simulations produced with the smoothed particle hydrodynamics code StarSmasher. This set explores different configurations of mass, radius, stellar evolution time, velocity at infinity and impact parameter for the two colliding stars. We have been able to analyze the temporal evolution of the percentage of unbound mass for all cases, obtaining that collisions produce a range of mass loss between 9.7 % and 19.3 %, with the impact parameter being the most influential value in the increase of this percentage. We have also visualized that the relaxation of the final remnant occurs quite quickly after the impact as long as the collision is radial. Only two days are necessary for the remnant mass to remain stable, as well as its velocity. In the case of non-radial collisions, the relaxation of the post-coalescence star is much more complex, since it is altered by successive collisions between the cores of the two primary stars. Finally, we also found that non-radial collisions are the only ones that result in a remnant with tangential rotational velocity, a fact that would favor the chemical enrichment of its constituent layers and modify its subsequent evolution.Since the detection of gravitational waves traveling through our universe, a new field of astrophysics has opened up, and with it many hypotheses and theoretical predictions have been put to the test. This is the case of the pair-instability mass gap (60 and 120 Msun. Gravitational wave signals have been detected whose primary and secondary black holes fall within the mass range where it was previously thought unthinkable that they could exist as a product of stellar evolution. Different mechanisms could explain these observations, among which the gravitational collapse of a particular type of remnant from a collision between two predecessor stars stands out. Multiple studies support this hypothesis, however, it is necessary to determine the incidence of the collision parameters on the main characteristics of the post-coalescence star, especially to corroborate that its final mass and chemical composition made it a suitable remnant to produce these special black holes. To achieve this goal, the hydrodynamic simulations of stellar collisions are a perfect tool. In this thesis, we have analyzed a set of simulations produced with the smoothed particle hydrodynamics code StarSmasher. This set explores different configurations of mass, radius, stellar evolution time, velocity at infinity and impact parameter for the two colliding stars. We have been able to analyze the temporal evolution of the percentage of unbound mass for all cases, obtaining that collisions produce a range of mass loss between 9.7 % and 19.3 %, with the impact parameter being the most influential value in the increase of this percentage. We have also visualized that the relaxation of the final remnant occurs quite quickly after the impact as long as the collision is radial. Only two days are necessary for the remnant mass to remain stable, as well as its velocity. In the case of non-radial collisions, the relaxation of the post-coalescence star is much more complex, since it is altered by successive collisions between the cores of the two primary stars. Finally, we also found that non-radial collisions are the only ones that result in a remnant with tangential rotational velocity, a fact that would favor the chemical enrichment of its constituent layers and modify its subsequent evolution

Methods for estimating the sampling variance of the standardized mean difference

One of the most widely used effect size indices for meta-analysis in psychology is the standardized mean difference (SMD). The most common way to synthesize a set of estimates of the SMD is to weight them by the inverse of their variances. For this, it is necessary to estimate the corresponding sampling variances. Meta-analysts have a formula for obtaining unbiased estimates of sampling variances, but they often use a variety of alternative, simpler methods. The bias and efficiency of five different methods that have been proposed and that are implemented in different computerized calculation tools are compared and assessed. The data from a set of published meta-analyses are also reanalyzed, calculating the combined estimates and their confidence intervals, as well as estimates of the specific, between-studies variance, using the five estimation methods. This test of sensitivity shows that the results of a meta-analysis can change noticeably depending on the method used to estimate the sampling variance of SMD values, especially under a random-effects model. Some practical recommendations are made about how to choose and implement the methods in calculation resourcesThis research was supported by a grant from the Ministerio de Economía, Industria y Competitividad of Spain, Project No. PSI2017-82490-P

Autoeficacia como mediador entre la violencia y la calidad de vida de adultos mayores de una institución de salud, Trujillo proyecto de investigación

El presente trabajo de investigación de tipo cuantitativa y diseño explicativo tuvo como objetivo general analizar si el constructo de autoeficacia actúa como mediador entre la violencia y la calidad de vida en adultos mayores. Se trabajó con 213 participantes de la ciudad de Trujillo (180 mujeres y 30 varones), entre 60 y 95 (M=72; DE=7.8). Como instrumentos de recolección de datos se emplearon los siguientes: La Escala Geriátrica de Maltrato al Adulto Mayor (GMS), Escala de Calidad de Vida WHOQOL-OLD, Escala de Auto-Eficacia Para Envejecer (EAEE). Dentro de los principales resultados la autoeficacia se revela como un factor mediador esencial en la interacción entre la violencia y la calidad de vida, así como en sus componentes (habilidades sensoriales, autonomía, muerte, actividades pasadas, presentes y futuras, participación social he intimidad) en adultos mayores. Mostrando un impacto indirecto significativo que mitiga los efectos adversos de la violencia. Esto subraya su papel crucial en la gestión efectiva de situaciones violentas y su contribución positiva al bienestar de este segmento de la población

Bifurcations with imperfect SO(2) symmetry and pinning of rotating waves

Copyright de los autore

Ordenes Generales y Santos de la División de la Izquierda del 8 de marzo al 2 de abril de 1833

Referente a la campaña contra las tribus Indígena

Non Fungible Tokens in Colombia: Legal Perspectives

Los NFTs son un certificado de propiedad y autenticidad sobre un contenido que puede ser digital o físico. Estos tokens criptográficos soportados en blockchain tienen múltiples implicaciones jurídicas.Este artículo tiene como objetivo aproximarse al concepto de NFTs desde distintas perspectivas a la luz del derecho colombiano. Entre estas, la conceptualización del NFT como valor y las implicaciones que tienen los NFTs en materia de derechos de autor. Con respecto a la conceptualización del NFT como valor, se estimó que no cumplen con los requisitos expuestos en la Ley 964 del 2005, por lo que no pueden publicitarse como vehículos de inversión amparados por el régimen jurídico colombiano. Frente a las implicaciones en derechos de autor, se determinó que el contenido asociado a los NFTs está protegido. Por tal motivo, no hay una transferencia de derechos de autor cuando se compra un NFT.NFTs are a certificate of ownership and authenticity of digital or physical content. These cryptographic tokens supported on the blockchain have multiple legal implications. This article aims to approach the concept of NFTs from different perspectives considering Colombian law. Among these, the conceptualization of the NFT as a value and its implications in terms of copyright. Regarding the conceptualization of the NFT as a value, it was estimated that they do not meet the requirements outlined in Law 964 of 2005. Therefore, NFTs cannot be advertised as investment vehicles protected in the Colombian legal regime. In respect of copyright implications, it was determined that the content associated with the NFTs is protected. Thus, there is no transfer of copyright when an NFT is purchased

La recuperación de una línea férrea abandonada en la comarca sur sevillana

Esta línea aunque se dividió para su construcción en tres Secciones, el autor de este trabajo de investigación lo ha hecho en cuatro Secciones, sería una magnifica y emblemática obra de ingeniería para su época, lo mismo que las restantes del Plan considerando los escasos medios técnicos, y tendría una longitud de 127 Km., por donde jamás circularía ningún tren a excepción del tramo Jerez-Jédula donde circularon algunos trenes de mercancías

Implicaciones legales del web scraping en el entrenamiento de modelos de inteligencia artificial generativa

El web scraping es una técnica que se usa para recopilar datos en Internet y almacenarlos en una base de datos. Ese proceso se usa, entre otras cosas, para entrenar modelos de inteligencia artificial generativa y ha generado controversia alrededor del mundo debido a sus riesgos legales. En este artículo se analizará la viabilidad legal del uso de técnicas de web scraping y se abordarán tensiones relacionadas con asuntos contractuales de los términos de servicio de las páginas web, los riesgos legales que se desprenden de estas técnicas y, en particular, del uso de obras protegidas en el entrenamiento de modelos de inteligencia artificial generativa, de protección de datos personales y de implicaciones penales; las licencias open source, open access y de Creative Commons, así como también los datos de dominio público y en cabeza del Estado colombiano. Este artículo pretende ser un marco teórico inicial para la discusión del web scraping en modelos de inteligencia artificial generativa, dado que, a la fecha de elaboración de este artículo, el desarrollo normativo y jurisprudencial sobre este tema es aún incipiente

Autoimmune neurological conditions associated with Zika virus infection

Zika virus (ZIKV) is an emerging flavivirus rapidly spreading throughout the tropical Americas. mosquitoes is the principal way of transmission of the virus to humans. ZIKV can be spread by transplacental, perinatal, and body fluids. ZIKV infection is often asymptomatic and those with symptoms present minor illness after 3 to 12 days of incubation, characterized by a mild and self-limiting disease with low-grade fever, conjunctivitis, widespread pruritic maculopapular rash, arthralgia and myalgia. ZIKV has been linked to a number of central and peripheral nervous system injuries such as Guillain-Barré syndrome (GBS), transverse myelitis (TM), meningoencephalitis, ophthalmological manifestations, and other neurological complications. Nevertheless, mechanisms of host-pathogen neuro-immune interactions remain incompletely elucidated. This review provides a critical discussion about the possible mechanisms underlying the development of autoimmune neurological conditions associated with Zika virus infection

El lugar del Básquet Femenino en La Plata

El basquetbol femenino en la ciudad de La Plata se encuentra cada día en mayor crecimiento, durante este trabajo realizamos un análisis de esta práctica desde una perspectiva de género, en donde reducimos nuestro campo de estudio a la categoría u15 a causa de que es en la misma en donde se producen los mayores contrastes en relación a la reglamentación del juego. Este trabajo tuvo como objetivo encontrar la fundamentación por la cual se produce esta distinción reglamentaria. Concluimos que la distinción producida no se da por una argumentación que provenga de la rama de lo biológico, sino al contrario, hallamos que era una cuestión mayormente social, en donde el basquetbol femenino se encuentra en una etapa de formación, entendida distintamente al básquetbol masculino donde se encuentra en una etapa consolidada de competición.Facultad de Humanidades y Ciencias de la Educació