Pulsations in M dwarf stars

We present the results of the first theoretical non-radial non-adiabatic pulsational study of M dwarf stellar models with masses in the range 0.1 to 0.5M_solar. We find the fundamental radial mode to be unstable due to an \epsilon mechanism caused by deuterium (D-) burning for the young 0.1 and 0.2M_solar models, by non-equilibrium He^3 burning for the 0.2 and 0.25M_solar models of 10^4Myr, and by a flux blocking mechanism for the partially convective 0.4 and 0.5M_solar models once they reach the age of 500Myr. The periods of the overstable modes excited by the D-burning are in the range 4.2 to 5.2h for the 0.1M_solar models and is of order 8.4h for the 0.2M_solar models. The periods of the modes excited by He^3 burning and flux blocking are in the range 23 to 40min. The more massive and oldest models are more promising for the observational detection of pulsations, as their ratio of instability e-folding time to age is more favourable.Comment: 5 pages, 4 figures, 2 tables. Accepted for publication in MNRAS Letters on 2011 October 11 Version 2 is the accepted manuscript with changes in boldfac

Adolfo Sánchez Vázquez y las memorias rotas de los exiliados españoles de 1939 en México: un concepto seminal para la sociología del pasado

Amb motiu de la commemoració del centenari del naixement d’Adolfo Sánchez Vázquez el 2015, es van celebrar a Mèxic una sèrie d’homenatges entorn de la seva figura i del seu llegat. L’article es planteja com a objectiu d’analitzar el concepte de “memoria rota” del filòsof espanyol, en diversos moments de la seva trajectòria. En primer lloc, com a memòria de testimoni i víctima, i anys a venir com a efecte de discontinuïtat històrica, política i vital entre l’experiència de l’exili i la memòria precària de les generacions successores. A partir d’aquest concepte seminal, hom es planteja com els records absents, oblidats, relegats i exclosos, implícits en les memòries trencades, adquireixen presència sota altres dispositius de salvaguarda i ús del passat: la commemoració i la postmemòria.To mark the occasion of the centenary celebrations for Adolfo Sánchez Vázquez’s birth, a series of tributes were held in Mexico in 2015 to honor both his figure and legacy. This paper aims to analyze the concept of broken memory from the Spanish philosopher through different stages; first, as a memory of witness and victim, and years later as an effect of historical, political and vital discontinuity amid the experience of exile and the lack of memory in successive generations. From this seminal concept, we propose that the absent, forgotten, relegated and excluded memories which are implicit in broken memories have gained presence through various other devices intended to safeguard and use the past: commemoration and post-memory.Con motivo de la conmemoración del centenario del natalicio de Adolfo Sánchez Vázquez en 2015, se llevaron a cabo en México una serie de homenajes en torno a su figura y legado. El artículo se plantea como objetivo analizar el concepto de memoria rota del filósofo español, en diferentes momentos de su trayectoria. Primero como memoria de testigo y víctima, y años después como efecto de discontinuidad histórica, política y vital entre la experiencia del exilio y la escasez de memoria en las generaciones sucesoras. A partir de este concepto seminal, se plantea cómo los recuerdos ausentes, olvidados, relegados y excluidos, implícitos en las memorias rotas, han cobrado presencia bajo otros dispositivos de resguardo y uso del pasado: la conmemoración y la posmemoria

De las TICs a las TACs : la importancia de crear contenidos educativos digitales

El progreso tecnológico y el desarrollo de sistemas informáticos de las últimas décadas, unido a su impacto en nuestra vida cotidiana, ha provocado un replanteamiento de las metodologías de enseñanza-aprendizaje en las aulas, permitiendo la incorporación en las aulas de las TICs y las TACs y así, favoreciendo el modelo TPACK, que implica el uso de contenidos educativos digitales en las aulas, por lo que se hace indispensable el desarrollo de la competencia digital de los docentes, que a su vez fomentará el desarrollo de la competencia digital de los alumnos, garantizando una educación y un proceso de enseñanza-aprendizaje adaptado a la sociedad del siglo XXI.Technological progress and the development of computer systems in recent decades, along with its impact on our daily lives has led to the emergence of the teaching-learning methodologies in the classroom, allowing the incorporation of ICT management and LTK in the classrooms, and thus favoring the TPACK model, which involves the use of digital educational content in the classrooms, so it is essential to the development of digital competence of teachers, which in turn promote the development of digital competence of students, thereby ensuring an education and teaching-learning process adapted to the XXI century

Collaborative work on distributed models

The collaborative work on distributed models is a big challenge in the robotic industry. To fragment the system into smaller components ease the software development because every agent can be specialized in a specific part, but the collaborative work of the different agents in the complete system present challenges such as to ensure consistency. A technology that provides support to establish remote repositories and the functionalities to work with them ensuring consistency and security is needed. The first goal of this thesis is to analyze the main challenges that occur in this kind of system. The next goal then is to choose which of the main tools that allow to work on remote repositories can cover these necessities and to show what approach can be followed to cover the different features with the chosen technology. In the end, the previous analysis is discussed to show which level of completion is reached.Escuela Técnica Superior de Ingeniería de TelecomunicaciónUniversidad Politécnica de Cartagen

Study of sdO models: mode trapping

We present the first description of mode trapping for sdO models. Mode trapping of gravity modes caused by the He/H chemical transition is found for a particular model, providing a selection effect for high radial order trapped modes. Low- and intermediate-radial order {\em p}-modes (mixed modes with a majority of nodes in the P-mode region) are found to be trapped by the C-O/He transition, but with no significant effects on the driving. This region seems to have also a subtle effect on the trapping of low radial order {\em g}-modes (mixed modes with a majority of nodes in the G-mode region), but again with no effect on the driving. We found that for mode trapping to have an influence on the driving of sdO modes (1) the mode should be trapped in a way that the amplitude of the eigenfunctions is lower in a damping region and (2) in this damping region significant energy interchange has to be produced.Comment: 10 pages, 13 figures, accepted for publication in MNRAS, 2009 December 1

Study of sdO models. Pulsation Analysis

We have explored the possibility of driving pulsation modes in models of sdO stars in which the effects of element diffusion, gravitational settling and radiative levitation have been neglected so that the distribution of iron-peak elements remains uniform throughout the evolution. The stability of these models was determined using a non-adiabatic oscillations code. We analysed 27 sdO models from 16 different evolutionary sequences and discovered the first ever sdO models capable of driving high-radial order g-modes. In one model, the driving is by a classical kappa-mechanism due to the opacity bump from iron-peak elements at temperature ~200,000 K. In a second model, the driving result from the combined action of kappa-mechanisms operating in three distinct regions of the star: (i) a carbon-oxygen partial ionization zone at temperature ~2 10^6 K, (ii) a deeper region at temperature ~2 10^7 K, which we attribute to ionization of argon, and (iii) at the transition from radiative to conductive opacity in the core of the star.Comment: 13 pages, 19 figures, accepted for publication in MNRAS, 2009 September 1

Airport terminals and desert planes: re-visiting the border in the terminal and no country for old men

Eighteen years after the 9/11 attacks in New York and Washington and in the present context of bitter conflict over the building of a wall across the US-Mexico border promoted by current President of the United States, Donald Trump, this article reads Steven Spielberg's The Terminal and the Coen Brothers' No Country for Old Men through the use of border theory and Cosmopolitanism. The main aim of the article is to reveal the mechanisms by which these films promote and intervene in an ongoing debate on the nature of the nation-state and the role of national borders in the creation of national identities. The two films appear to consolidate certain social imaginaries while highlighting the extent to which, though the turn of the millennium seemed to promise a world with more mobile, hybrid identities in multicultural spaces, most social and cultural realities still tend to be trapped within nation-state borders which prove the staying power of national identities

Recurso Humanos análisis de rotación de personal en los docentes del Bachillerato Internacional en el colegio CEBI en la ciudad de Ambato

Excessive turnover in the College CEBI specifically in the area of International Baccalaureate took being analyzed what are the causes , reasons and possible solutions to this problem. Interviews with teachers and authorities currently working in the institution to observe various aspects , including the work environment, motivations and disincentives , as well as the commitment of teachers to the school and the International Baccalaureate program was conducted . Finally with all the data it was possible to know what the current situation of teachers and authorities , to give conclusions and recommendations that will help you have a better working environment with increased communication among stakeholders International Baccalaureate and thus reduce turnover staff.La excesiva rotación de personal en el Colegio CEBI específicamente en el área del Bachillerato Internacional, llevó a que se analicen cuáles son las causas, motivos y posibles soluciones a este problema. Se realizaron entrevistas a docentes y autoridades que actualmente trabajan en la institución para observar varios aspectos, entre ellos, el clima laboral, motivaciones y desmotivaciones, como también el compromiso de los docentes con el colegio y con el programa del Bachillerato Internacional. Finalmente con todos los datos obtenidos se pudo saber cuál es la situación actual de los docentes y autoridades, para dar conclusiones y recomendaciones que ayudarán a conseguir un mejor clima laboral con mayor comunicación entre los involucrados del Bachillerato Internacional y así reducir la rotación de personal

Phenotypic evolution in microalgae: a dramatic morphological shift in Dictyosphaerium chlorelloides (Chlorophyta) after exposure to TNT

Phenotypic evolution in microalgae: a dramatic morphological shift in Dictyosphaerium chlorelloides (Chlorophyta) after exposure to TNT. The occurrence of rapid morphological evolution in the microalga Dictyosphaerium chlorelloides (Chlorophyta) was induced after exposure of the wild strains of the alga to the potent algal poison 2,4,6-trinitrotoluene (TNT). After exposing a wildtype population (consisted of representative spherical-ellipsoidal cells) to doses of TNT that were lethal for most of the cells, a TNT-resistant spindle-shaped mutant was able to proliferate. This spindleshaped mutant appeared spontaneously by rare mutations before the selective treatment: in deed, it was already present in the wild population. The frequency of the mutants within the ancestral population seemed to be determined by the balance between the rate of accumulation by recurrent mutation and the rate of elimination by selection (ranging 10-102 spindle-shaped mutants per 106 cells). We hypothesize that clone selection could take place in asexual populations of microalgae by selection of rare, pre-selective genotypes, driven by a drastic selective pressure subsequent to a catastrophic environmental changeEvolucion fenotípica en microalgas: un cambio morfológico espectacular en Dictyosphaerium chlorelloides (Chlorophyta) tras la exposición a TNT. Un cambio morfológico muy rápido tiene lugar en Dictyosphaerium chlorelloides (Chlorophyta) tras la exposición de cepas salvajes al potente alguicida 2,4,6 trinitrotolueno (TNT). Las cepas salvajes, sensibles al TNT, tienen una morfología típica esférico-elipsoidal. Tras exponer dichas cepas a dosis letales de TNT, solamente sobreviven células resistentes al tóxico cuya silueta es fusiforme. Estos resistentes fusiformes aparecen como consecuencia de mutaciones espontáneas que tienen lugar antes de exponer las cepas salvajes al agente selectivo (TNT): es decir, las células fusiformes estaban presentes en la población salvaje. La frecuencia de mutantes fusiformes en las poblaciones salvajes está definida por el equilibrio entre la tasa de acumulación de mutantes y la tasa en que son eliminados por tener una eficiencia biológica menor (10-102 mutantes fusiformes por 106 células salvajes). Se propone que la selección de clones podría ser un mecanismo de evolución adaptativa en poblaciones de microalgas asexuales. Este evento opera mediante la selección de genotipos pre-selectivos que aparecen como consecuencia del incremento de la presión de selección como fruto de eventos catastróficos en el medio ambient