Stochastic angular momentum slews and flips and their effect on discs in galaxy formation models

The angular momentum of galactic discs in semi-analytic models of galaxy formation is usually updated in time as material is accreted to the disc by adopting a constant dimensionless spin parameter and little attention is paid to the effects of accretion with misaligned angular momenta. These effects are the subject of this paper, where we adopt a Monte-Carlo simulation for the changes in the direction of the angular momentum of a galaxy disc as it accretes matter based on accurate measurements from dark-matter haloes in the Millennium II simulation. In our semi-analytic model implementation, the flips seen the dark matter haloes are assumed to be the same for the cold baryons; however, we also assume that in the latter the flip also entails a difficulty for the disc to increase its angular momentum which causes the disc to become smaller relative to a no-flip case. This makes star formation to occur faster, specially in low mass galaxies at all redshifts allowing galaxies to reach higher stellar masses faster. We adopt a new condition for the triggering of starbursts during mergers. As these produce the largest flips it is natural to adopt the disc instability criterion to evaluate the triggering of bursts in mergers instead of one based on mass ratios as in the original model. The new implementation reduces the average lifetimes of discs by a factor of 2, while still allowing old ages for the present-day discs of large spiral galaxies. It also provides a faster decline of star formation in massive galaxies and a better fit to the bright end of the luminosity function at z = 0.Comment: 15 pages, 12 figures, MNRAS in pres

The complex dust formation zone of the AGB star IRC+10216 probed with CARMA 0.25 arcsec angular resolution molecular observations

We present low spectral resolution molecular interferometric observations at 1.2 mm obtained with the Combined Array for Research in Millimetre-wave Astronomy (CARMA) towards the C-rich AGB star IRC+10216. We have mapped the emission of several lines of SiS, H13CN, SiO, and SiC2 in the ground and first excited vibrational states with a high angular resolution of 0.25 arcsec. These observations have allowed us to partially resolve the emission of the envelope at distances from the star <50 stellar radii (R*), where the stellar wind is mainly accelerated. The structure of the molecular emission has been modelled with a 3D radiation transfer code. The emission of line SiS(v=0,J=14-13) is best reproduced with a set of maser emitting arcs arranged between 5 and 20 R*. The abundance of H13CN with respect to H2 decreases from 8e-7 at 1-5 R* to 3e-7 at 20 R*. The SiO observations are explained with an abundance <2e-8 in the shell-like region between 1 and 5 R*. At this point, the SiO abundance sharply increases up to (2-3)e-7. The vibrational temperature of SiO increases by a factor of 2 due North-East between 20 and 50 R*. SiC2 is formed at the stellar surface with an abundance of 8e-7 decreasing down to 8e-8 at 20 R* probably due to depletion on to dust grains. Several asymmetries are found in the abundance distributions of H13CN, SiO, and SiC2 which define three remarkable directions (North-East, South-Southwest, and South-East) in the explored region of the envelope. There are some differences between the red- and blue-shifted emissions of these molecules suggesting the existence of additional asymmetries in their abundance distributions along the line-of-sight.Comment: 22 pages, 16 figures, 9 tables, accepted for publication in MNRA

Fontes culturais para a aprendizagem. Estudo na micro, pequena e média empresa em Celaya

The objective of this research project is to analyze information sources that micro, small and medium-size enterprises use in order to learn about their business activity. 342 enterprises from the manufacturing sector in the city of Celaya, in Guanajuato, Mexico, were interviewed through a qualitative analysis. The results show that these companies use 26 different information sources in order to learn about their activities, which can be re-grouped in seven categories: cross-organizational logic, specialized sources and ICTs; formal sources of knowledge; organizational sources; communication and advertising mediums; informal sources of communication; the entrepreneur’s own experience; and the absence of information and knowledge. The importance and use of each of them depends on the size of the enterprise and the type of industry it belongs to; while they all contribute to developing or promoting bonds with other enterprises or entities that help strengthen the enterprise’s learning capability.Este trabajo de investigación tiene como objetivo analizar las fuentes de información que utiliza la micro, pequeña y mediana empresa para aprender sobre su actividad empresarial. A través de un análisis cualitativo se entrevistaron a 342 empresas del sector manufacturero de la ciudad de Celaya, Guanajuato, México. Los resultados muestran que las empresas utilizan 26 diferentes fuentes de información para aprender sobre su actividad, las cuales se reagrupan en siete categorías: lógicas interorganizacionales, fuentes especializadas y TICs; fuentes formales de conocimiento; fuentes organizacionales; medios de comunicación y publicidad; fuentes informales de comunicación; experiencia propia del empresario; y ausencia de información y conocimiento. La importancia y uso de cada una de ellas depende del tamaño de la empresa y de la industria a la que pertenece, pero todas ellas contribuyen a desarrollar, consolidar o potenciar vínculos con otras empresas o entes que ayuden a potenciar la capacidad de aprender de la organización.&nbsp;Este trabalho de pesquisa tem como objetivo analisar as fontes de informação que utiliza a micro, pequena e média empresa para aprender sobre sua atividade empresarial. Através de uma análise qualitativa, entrevistou-se a 342 empresas do setor manufatureiro da cidade de Celaya, Guanajuato, México. Os resultados mostram que as empresas utilizam 26 diferentes fontes de informação para aprender sobre sua atividade, as quais se reagrupam em sete categorias: lógicas interorganizacionais, fontes especializadas e TICs; fontes formais de conhecimento; fontes organizacionais; meios de comunicação e publicidade; fontes informais de comunicação; experiência própria do empresário; e ausência de informação e conhecimento. A importância e uso de cada uma delas depende do tamanho da empresa e da indústria a que pertence, mas todas elas contribuem para desenvolver, consolidar ou potenciar vínculos com outras empresas ou entes que ajudem a potenciar a capacidade de aprender da organização

Utilización y valoración de los servicios de orientación desde la perspectiva de los universitarios

Las universidades, tanto a nivel internacional como nacional contemplan en sus estructuras organizativas servicios de apoyo al estudiante universitario. Estos recursos tienen como propósito servir de apoyo al estudiante en diversas problemáticas universitarias que se puedan plantear a lo largo de sus estudios. Esta investigación pretende conocer la utilización y valoración que hacen los destinatarios de estos servicios. Así como detectar posibles diferencias significativas según sexo y rama de conocimiento de la titulación. La población objeto de estudio se circunscribe a la Universidad de Sevilla. Para ello se parte de una muestra de 137 estudiantes de todos los centros propios de la misma y se diseña un cuestionario ad hoc. El análisis de los datos obtenidos revela una baja utilización de los servicios de apoyo así como diferencias significativas en cuanto a servicios de apoyo pedagógico, discapacidad, salud, bienestar y asesoramiento vocacional.Universities, both at international and national levels in their organizational structures provides support services to the college student. These resources are intended to support the student in various university issues that may arise throughout college. This research aims to determine the use and assessment that the recipients of these services. And detect any significant differences by sex and branch of knowledge. The population under study belongs to the University of Seville. The sample consists of 137 students of all own centers thereof and an ad hoc questionnaire was designed. Analysis of the data reveals a low utilization of support services as well as significant differences in education support services, disability, health, welfare and vocational counseling.Unión Europea, Erasmus Ref: 526600-LLP-1-2012-IT-Erasmus-Esi

Renta Disponible, Ahorro y Consumo: Análisis económico enfocado en la pandemia

El presente Trabajo de Fin de Grado se adentra en un análisis profundo de la renta disponible, el consumo y el ahorro, poniendo un énfasis particular en su evolución temporal y, más crucialmente, en su situación durante la crisis de la pandemia de COVID-19, así como en las transformaciones que resultaron de esta conmoción.Durante este período crítico, la pérdida de empleos, las reducciones salariales y los cambios en los patrones de gasto han tenido un impacto notable en estos tres elementos económicos fundamentales. Los hogares se vieron obligados a replantear sus finanzas y ajustar sus prioridades financieras en respuesta a las circunstancias vividas.El propósito central de esta investigación radica en comprender a fondo cómo la crisis de salud global ha dejado su huella en estos componentes esenciales de la economía.Además, se busca arrojar luz sobre cómo estas transformaciones económicas han influido en la vida de las personas y las familias, desde la capacidad de satisfacer sus necesidades básicas hasta las decisiones relacionadas con la planificación financiera a largo plazo.<br /

Stochastic angular momentum slews and flips and their effect on discs in galaxy formation models

The angular momentum of galactic discs in semi-analytic models of galaxy formation is usually updated in time as material is accreted to the disc by adopting a constant dimensionless spin parameter and little attention is paid to the effects of accretion with misaligned angular momenta. These effects are the subject of this paper, where we adopt a Monte Carlo simulation for the changes in the direction of the angular momentum of a galaxy disc as it accretes matter based on accurate measurements from dark-matter haloes in the Millennium II simulation. In our semi-analytic model implementation, the flips seen in the dark-matter haloes are assumed to be the same for the cold baryons; however, we also assume that in the latter the flip also entails a difficulty for the disc to increase its angular momentum which causes the disc to become smaller relative to a no-flip case. This makes star formation to occur faster, especially in low-mass galaxies at all redshifts allowing galaxies to reach higher stellar masses faster. We adopt a new condition for the triggering of starbursts during mergers. As these produce the largest flips it is natural to adopt the disc instability criterion to evaluate the triggering of bursts in mergers instead of one based on mass ratios as in the original model. The new implementation reduces the average lifetimes of discs by a factor of ∼2, while still allowing old ages for the present-day discs of large spiral galaxies. It also provides a faster decline of star formation in massive galaxies and a better fit to the bright end of the luminosity function at z = 0.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

Suggestive evidence for association between L-type voltagegated calcium channel (CACNA1C) gene haplotypes and bipolar disorder in Latinos: a family-based association stud

Objectives: Through recent genome-wide association studies (GWASs), several groups have reported significant association between variants in the calcium channel, voltage-dependent, L-type, alpha 1C subunit (CACNA1C) and bipolar disorder (BP) in European and European-American cohorts. We performed a family-based association study to determine whether CACNA1C is associated with BP in the Latino population. Methods: This study included 913 individuals from 215 Latino pedigrees recruited from the USA, Mexico, Guatemala, and Costa Rica. The Illumina GoldenGate Genotyping Assay was used to genotype 58 single-nucleotide polymorphisms (SNPs) that spanned a 602.9-kb region encompassing the CACNA1C gene including two SNPs (rs7297582 and rs1006737) previously shown to associate with BP. Individual SNP and haplotype association analyses were performed using Family-Based Association Test (version 2.0.3) and Haploview (version 4.2) software. Results: An eight-locus haplotype block that included these two markers showed significant association with BP (global marker permuted p = 0.0018) in the Latino population. For individual SNPs, this sample had insufficient power (10%) to detect associations with SNPs with minor effect (odds ratio = 1.15). Conclusions: Although we were not able to replicate findings of association between individual CACNA1C SNPs rs7297582 and rs1006737 and BP, we were able to replicate the GWAS signal reported for CACNA1C through a haplotype analysis that encompassed these previously reported significant SNPs. These results provide additional evidence that CACNA1C is associated with BP and provides the first evidence that variations in this gene might play a role in the pathogenesis of this disorder in the Latino population

Stochastic angular momentum slews and flips and their effect on discs in galaxy formation models

The angular momentum of galactic discs in semi-analytic models of galaxy formation is usually updated in time as material is accreted to the disc by adopting a constant dimensionless spin parameter and little attention is paid to the effects of accretion with misaligned angular momenta. These effects are the subject of this paper, where we adopt a Monte Carlo simulation for the changes in the direction of the angular momentum of a galaxy disc as it accretes matter based on accurate measurements from dark-matter haloes in the Millennium II simulation. In our semi-analytic model implementation, the flips seen in the dark-matter haloes are assumed to be the same for the cold baryons; however, we also assume that in the latter the flip also entails a difficulty for the disc to increase its angular momentum which causes the disc to become smaller relative to a no-flip case. This makes star formation to occur faster, especially in low-mass galaxies at all redshifts allowing galaxies to reach higher stellar masses faster. We adopt a new condition for the triggering of starbursts during mergers. As these produce the largest flips it is natural to adopt the disc instability criterion to evaluate the triggering of bursts in mergers instead of one based on mass ratios as in the original model. The new implementation reduces the average lifetimes of discs by a factor of ∼2, while still allowing old ages for the present-day discs of large spiral galaxies. It also provides a faster decline of star formation in massive galaxies and a better fit to the bright end of the luminosity function at z = 0.Instituto de Astrofísica de La PlataFacultad de Ciencias Astronómicas y Geofísica

Descripción del cráneo de Bramocharax caballeroi Contreras & Rivera 1985 (Pisces, Characidae), pez endémico del Lago de Catemaco, Veracruz, México.

The Bramocharax genus is distributed from Central America to Mexico. Until now the species known are Bramocharax bransfordi collected in Nicaragua and Costa Rica, B. dorioni and B. baileyi from Guatemala and B. caballeroi from Catemaco Lake, Veracruz, Mexico. The aim of this work is to realize a detailed description of the skull for Bramocharax caballeroi from the analysis of 37 different topotypes. The skull of this species has 58 osteological elements, 49 of them coupled. Shape is oval in lateral view, because the bones of the snout (ethmoid, vomer, lateral ethmoid, dentary, maxillae, premaxillae, ecto and mesopterygoids) and the frontal and circunorbitals are elongated. The dorsal margin is slightly concave and the anterior part is elongated. In specimens less than 80 mm, all the bones are smoother, with more regular edges. With the age increase, they become more robust with more irregular edges. A comparison of the skull between B. caballeroi and Astyanax mexicanus resulted in 25 bones with differences, while with Astyanax fasciatus, main contrasts were the supraoccipital length, the shape of the opercles and the infraorbital 3. In addition there are important differences in the dentition, gill rackers, as well as suspensory pharingeals and pharyngeal plates with respect to Astyanax.El género Bramocharax se distribuye del centro-norte de Centro América a México. Hasta este momento se conoce a Bramocharax bransfordi de Nicaragua y Costa Rica, a B. dorioni y B. baileyi de Guatemala y a B. caballeroi del lago de Catemaco, Veracruz, México. El trabajo tuvo por objetivo estudiar detalladamente el cráneo de Bramocharax caballeroi a partir del análisis de 37 topotipos de diferentes tallas y compararlo con otras especies relacionadas. B. caballeroi presenta 58 huesos en su cráneo, de los cuales 49 son elementos pareados. En vista lateral su perfil es ovalado, debido a los huesos que conforman el hocico (etmoides, vómer, etmoides lateral, mandíbula, maxila, premaxila, ecto y mesopterigoides), así como el frontal y los circunorbitales, son alargados. El margen dorsal es ligeramente cóncavo y la parte anterior alargada. En los ejemplares menores a 80 mm todos los huesos son más lisos y conforme los organismos tienen una talla mayor, se hacen más robustos y los bordes de cada hueso se hacen más irregulares. Al comparar el cráneo de B. caballeroi con el de Astyanax mexicanus se encontraron diferencias en 25 huesos, mientras que al hacerlo con A. fasciatus, los principales contrastes fueron la longitud del supraoccipital, la forma del opérculo y del infraorbital 3. Adicionalmente, se encontraron diferencias importantes en la dentición y en las branquiespinas así, como en las placas y suspensores faríngeos con respecto a los Astyanax

Description of cognitive processes involved in essay-writing

Se estudiaron los procesos de planificación, transcripción, revisión, meta cognitivos y afectivos implicados en la construcción de un ensayo argumentativo realizado por 11 universitarios. Se aplicaron varios instrumentos elaborados por los autores: el Protocolo Verbal, el Cuestionario de Estrategias para Escritura de Ensayos, las Escalas de Auto-percepción de Eficacia en la Escritura y de Actitudes Hacia la Escritura,. Se hizo un conteo de frecuencias por componente para los datos textuales obtenidos a través del Protocolo Verbal, a partir de un análisis de contenido;, luego se calcularon porcentajes dentro de cada categoría para cada sujeto según su ejecución con respecto al grupo y se realizó un análisis descriptivo para los auto reportes. En la observación de los procesos a través del protocolo verbal, los participantes durante el proceso de la escritura del ensayo evidenciaron los componentes de planificación, transcripción, revisión y metacognición. Sin embargo, en revisión, ninguno de ellos presentó revisión por otros y en el componente de metacognición solamente dos participantes demostraron tener conciencia de la estructura del ensayo. En relación con los auto reportes, los participantes reportaron moderadas y altas estrategias en planificación, revisión, metacognición; y un nivel de desempeño entre moderado y alto de actitudes hacia la escritura y hacia la autopercepción de eficacia en la escritura cuando elaboran un ensayo.The processes of planning, transcription, revision, metacognition and affection involved in the construction of an argumentative essay written by 11 university students were examined. Several assessment instruments designed by the authors were administered: The Verbal Protocol, The Essay-writing Strategies Questionnaire and the Self-Perception Scales on Writing Efficacy and Attitude Toward Writing. A frequency count per component of the textual data obtained by means of the Verbal Protocol and based on a content analysis was carried out. Later, the percentages within each category were calculated for each subject, based on his/her performance with respect to the group. Finally, a descriptive analysis of the self-reports was done. At the time of observation of the above mentioned processes using the Verbal Protocol, six participants showed evidence of planning, transcription, revision and meta-cognition during the writing process. However, when doing revision, none of them presented revision by others, and on the metacognition component only two participants demonstrated their awareness of the essay structure. With respect to self-reports, the participants expressed moderate to high levels of planning, revision and metacognition strategies, as well as moderate to high scores on attitudes toward writing and self-perception of writing efficacy when elaborating an essay