Birkhoff’s theorem for Einstein gravity and beyond

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2023, Tutor: Pablo Bueno GómezBirkhoff’s theorem establishes that any spherically symmetric vacuum solution of Einstein’s equations is necessarily static and uniquely given by the Schwarzschild metric. In this TFG we prove this theorem for Einstein gravity and several of its extensions, which include the presence of electric charge as well as higher-curvature terms in the action. More precisely, we explicitly prove Birkhofflike theorems for: Einstein, Einstein-Maxwell, Einstein-Gauss-Bonnet and Einstein-Maxwell-Gauss-Bonnet theories in general dimensions. In all cases, starting from a general spherically symmetric ansatz, we are able to show that the equations of motion impose the staticity condition, and fully constrain the metric to take the form of the unique static and spherically symmetric spacetime of each theory. We also comment on the validity of the theorem for general Lovelock theories and its current status for more general higher-curvature theories of gravit

A Xesta de cómo América nasceu da melodía, unha particular Argonáutica

During his long and fruitful stay in Cuba, Jesuit José Rubinos, born in Corunna, published most of his literary production: hundreds of editorials and research articles, the epic poem entitled 'Covadonga', the short drama piece 'O Velliño', several poem collections of his own lyrical creations and some odd poems which saw the light in magazines and newspapers or were published as loose leaflets. This is the case of 'A Xesta de cómo América nasceu da melodía', a work of classical inspiration which will be studied in this paper, by focusing on the analysis of its characteristics and its debt to classical tradition.En la larga y fecunda etapa de su estancia en Cuba, el jesuita coruñés José Rubinos publica la mayor parte de su producción literaria: cientos de artículos de opinión o de investigación, la epopeya Covadonga, la pequeña pieza dramática O Velliño, varios poemarios con sus creaciones líricas y algunos poemas sueltos que vieron la luz en revistas y periódicos o se publicaron en folletos independientes. Éste es el caso de A Xesta de cómo América nasceu da melodía, la obra de inspiración clásica de la que nos vamos a ocupar en este trabajo, estudiando sus características y su deuda con la tradición clásica.Na longa e fecunda etapa da súa estadía en Cuba, o xesuíta coruñés Xosé Rubinos dá ao prelo o máis da súa produción literaria: centos de artigos de opinión ou de investigación, a epopeia Covadonga, a pequena peza dramática O Velliño, varios poemarios coas súas creacións líricas e algúns poemas soltos que viron a luz en revistas e xornais ou se publicaron en folletos independentes. É este o caso de A Xesta de cómo América nasceu da melodía, a obriña de inspiración clásica da que nos imos ocupar neste traballo, estudando as súas características e a súa débeda coa literatura clásica

Nivel socioecónomico asociado a Apendicitis Complicada

La apendicitis aguda es el padecimiento quirúrgico más frecuente en nuestra población, cuya etiologíaes multifactorial. En el Hospital General Raymundo Abarca Alarcón de Chilpancingo Gro., durante el periodo del 1 de enero al 31 de diciembre de 2012,se atendieron 97 casos con diagnóstico de apendicitis complicada en edad de 0 a 15 años

Searching for δ\delta Scuti-type pulsation and characterising northern pre-main-sequence field stars

A photometric variability study of a sample of northern field stars, which previously classified as either PMS or Herbig Ae/Be objects, has been undertaken with the purpose of detecting {\delta} Scuti-type pulsations. Determination of physical parameters for these stars has also been carried out to locate them on the HR diagram and check the instability strip for this type of pulsators. Multichannel photomultiplier and CCD time series photometry in the uvby Str\"omgren and BVI Johnson bands were obtained during four consecutive years from 2007 to 2010. The light curves have been analysed, and a variability criterion has been established. Among the objects classified as variable stars, we have selected those which present periodicities above 4 d^(-1), which was established as the lowest limit for {\delta} Scuti-type pulsations in this investigation. Finally, these variable stars have been placed in a colour-magnitude diagram using the physical parameters derived with the collected uvby{\beta} Str\"omgren-Crawford photometry. Five PMS {\delta} Scuti- and three probable {\beta} Cephei-type stars have been detected. Two additional PMS {\delta} Scuti stars are also confirmed in this work. Moreover, three new {\delta} Scuti- and two {\gamma} Doradus-type stars have been detected among the main-sequence objects used as comparison or check stars.Comment: Accepted for publication in Section 14. Catalogs and data of Astronomy and Astrophysics. The official date of acceptance is 17/06/2014. 12 pages, 4 figures and 8 table

Proceso de externalziación como estrategia de resolución del conflicto en hogares de protección

El presente trabajo de investigación – intervención busca investigar e intervenir desde el proceso de externalización del conflicto en un grupo de Jóvenes del Hogar Teresa Toda ubicado en el municipio de Floridablanca en el Barrio Zapamanga tercera etapa, para esto se hace uso de las metáforas con la finalidad de analizar, comprender e intervenir las situaciones que alteran la convivencia. Este trabajo se realizó con una metodología cualitativa basada en los aportes de la narrativa, la cual desde las metáforas permite comprender e intervenir el discurso, expresado desde los actores sociales. El proceso de investigación – intervención permitió generar compromisos individuales y grupales frente al manejo y superación del conflicto. Las técnicas investigativas utilizadas fueron: La observación participante, las entrevistas no estructuradas, las metáforas construidas por los actores sociales entre otros. Para la comprensión de la información se emplearon Diarios de Campo y la categorización. Palabras Claves: Externalización, resolución del conflicto, orden y tiempo.The purpose of the herein research work is to investigate and intervene from the process of externalization of the conflict a group of juveniles sheltered at Hogar Teresa Toda, located in the municipality of Floridablanca, Barrio Zapamanga, tercera etapa (Third Stage),. The work was conducted through metaphors so as to analyze, understand and intervene in situations disturbing conviviality. A qualitative methodology was used based on help from narrative resources, which, through metaphors, allows understanding of and intervention in the discourse expressed by the social actors. The investigation-intervention process allowed generation of individual and group commitments vis-à-vis handling and solution of the conflict. The investigative techniques used were: Participant observation, non-structured interviews, and metaphors constructed by the social actors and others. Field Diaries and categorization were used for understanding of the information. Key words: Externalization, solution of the conflict, order and time

Bovine Mastitis in Cuba. Review article

Mastitis is the main disease affecting dairy cattle. Reducing it is one of the most important tasks Cuban cattle raising has today. Hence, it is essential to know the national background, and related research contribution. The literature shows that the frequency of mastitis caused by wellknown pathogens has declined; whereas mastitis caused by minor pathogens is more frequent. Research on the incidence of mastitis should be done in the eastern part of the country. The economic losses associated to the disease, antimicrobial sensitivity of the microorganisms involved, and the differences between mechanical and manual milking must be further researched as well. Somatic cell count must also be extended to the rest of the country. Milking routine and hygiene should be improved, increased production of medication to control mastitis, and implementation of research on natural products and alternative treatments must be encouraged (homeopathy and Eucalyptus). A program to control bovine mastitis would be useful, based on recent research done in Cuba, including several products made in the country. Updated international methods to fight the disease are based on state of the art methodologies

Excluida y traicionada: una Medea víctima de la Guerra Civil española

El final de la guerra civil española en 1939 trajo victoria para el bando sublevado, pero no paz para todos, pues los perdedores fueron perseguidos y vieron su seguridad comprometida hasta la llegada de la democracia, casi cuarenta años después. Una parte de ellos se exilió y otros optaron por echarse al monte y vivir como refugiados en condiciones penosas y permanentemente acosados. En este contexto sitúa Manuel Lourenzo su Medea dos fuxidos, una reescritura de la leyenda de Jasón y Medea, en la que la exclusión impuesta por las circunstancias políticas adquiere una especial dureza para la heroína por su condición de mujer. En este trabajo analizaremos las técnicas de transformación del mito clásico en función de la nueva realidad que lo envuelve