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

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

Effects of clinical experience in the nursing student attitudes toward people with psychiatric disabilities

Indexación: Scopus; Scielo.En la formación del estudiante de pregrado de Enfermería se hace fundamental la elección de experiencias de aprendizaje significativas. Objetivo: Determinar el efecto de la experiencia clínica en servicios de psiquiatría, en las actitudes de estudiantes de Enfermería hacia las personas con discapacidad psiquiátrica. Material y método: Diseño cuasi experimental de pre y postest. La muestra incluyó un total de 84 estudiantes de Enfermería de tercer año de dos universidades de Santiago de Chile. El total de la muestra completó la "Escala de Actitudes hacia las Personas con Discapacidad" (EAPD) forma G. Se consideró como intervención las estrategias usadas en las asignaturas clínicas de enfermería psiquiátrica en ambas universidades. Se realizó prueba t de student para muestras relacionadas. Resultados: Se encontró diferencia estadísticamente significativa (p< 0,05) en el postest, lo que está relacionado con las experiencias de aprendizaje que consideran el contacto con personas con discapacidad psiquiátrica, en diferentes dispositivos de la red de psiquiatría y el acompañamiento docente directo. Conclusión: Estos hallazgos validan la importancia de la elección de experiencias clínicas, en los currículos de formación de Enfermería, como instancias que disminuyen las actitudes negativas como la estigmatización.The choice of meaningful learning experiences becomes essential in basic Nursing education programs. The purpose of this study is to determine the effect of clinical experience in psychiatric services in Nursing students' attitudes towards people with mental illnesses. A quasi-experimental design method of pre-test and post-test was used. The sample was made up of 84 third-year-nursing students from two universities in Santiago, Chile. All of the participants completed the Scale of Attitudes Toward Disabled Persons (SADP)-G. The strategies used in subjects of psychiatric nursing at both universities were regarded as intervention. Student t test for related samples was performed. Results: Respondents reported statistically significant difference (p <0.05) in the post test, which is associated with learning experiences that consider contact with people with mental illness in any of the different psychiatry network nodes and direct educational support. Conclusion: Validate the importance of including the clinical experience in the nursing training curriculum as a way of reducing negative attitudes of Nursing students, such as stigmatization, towards people with mental illnesses.https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0717-95532017000300125&lng=en&nrm=iso&tlng=e

Flexural characteristics of sunlight-aged polyester composites: influence of processing variables

[EN] This work presents the results of flexural tests carried out on samples aged for different periods of time in a UV-Visible light chamber. The processing variables studied were the type of reinforcing fabric, the resin type, and the cure conditions. The evolution of flexural characteristics with time exposure adjusts to a mathematical model that corresponds to a damped exponential curve. The aging degree varies between 16 and 41%, depending on the preparation of the composites and the mechanical characteristics of the material. The aged material featured losses of its mechanical properties, and more on toughness than on strength properties. The kind of unsaturated o-phthalic polyester resin used showed no influence on the loss of mechanical properties. High cure temperatures decreased the loss of toughness to a higher degree than that observed for the loss of strength. The configuration of the reinforced fabrics used also influenced the mechanical properties: a mixed taffeta-multiaxial reinforced configuration leads to a high loss index on toughness properties and modulus of the composite.Segovia-López, F.; Ferrer, C.; Salvador Moya, MD.; Amigó, V. (2002). Flexural characteristics of sunlight-aged polyester composites: influence of processing variables. Journal of Testing and Evaluation. 30(1):20-26. doi:10.1520/JTE12285JS202630

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

Influence of early romantic relationships on adolescents' sexism

The aim of this study was to analyse the influence of romantic relationships on adolescents sexism. We primed some of the participants with their past and/or present relationship experiences before assessing their sexism. A sample of 130 adolescents (67 boys and 63 girls) from Spanish high schools participated in the study. Half of them were asked to report on their relationship experience first before responding to an ambivalent sexism inventory. The other half of the sample responded first to the sexism inventory and then reported on their relationship experience. The results of this study showed that when participants relationship experiences were primed, they reported higher endorsement of sexist beliefs: boys reported higher BS and HS, whereas girls reported higher BS.El objetivo de este trabajo fue analizar la influencia que las primeras relaciones de pareja tienen en el sexismo de los y las adolescentes. Para ello, utilizamos un procedimiento que hizo salientes a algunos de los participantes sus experiencias pasadas y actuales de pareja, antes de evaluar su sexismo. Participaron en el estudio 130 adolescentes (67 chicos y 63 chicas) de centros educativos españoles. A la mitad de la muestra, se le solicitó que informaran sobre sus relaciones de pareja antes de responder a un cuestionario que medía el sexismo ambivalente. La otra mitad cumplimentó inicialmente el cuestionario de sexismo y después informó de sus relaciones de pareja. Los resultados de este estudio mostraron que al hacer salientes las relaciones de pareja, el sexismo informado por las personas participantes es mayor: en el caso de los chicos, tanto el SB como el SH, y en el caso de las chicas, el S

Seismology of beta Cephei stars: differentially-rotating models for interpreting the oscillation spectrum of nu-Eridani

A method for the asteroseismic analysis of beta Cephei stars is presented and applied to the star nu Eridani. The method is based on the analysis of rotational splittings, and their asymmetries using differentially-rotating asteroseismic models. Models with masses around 7.13 M_sun, and ages around 14.9 Myr, were found to fit better 10 of the 14 observed frequencies, which were identified as the fundamental radial mode and the three L=1 triplets g, p, and p. The splittings and aymmetries found for these modes recover those provided in the literature, except for p. For this last mode, all its non-axysimmetric components are predicted by the models. Moreover, opposite signs of the observed and predicted splitting asymmetries are found. If identification is confirmed, this can be a very interesting source of information about the internal rotation profile, in particular in the outer regions of the star. In general, the seismic models which include a description for shellular rotation yield slightly better results as compared with those given by uniformly-rotating models. Furthermore, we show that asymmetries are quite dependent on the overshooting of the convective core, which make the present technique suitable for testing the theories describing the angular momentum redistribution and chemical mixing due to rotationally-induced turbulence.Comment: 11 pages, 9 figures, 8 tables. ApJ (in press