On the probability of reaching a barrier in an Erlang(2) risk process

HolaIn this paper the process of aggregated claims in a non-life insurance portfolio as defined in the classical model of risk theory is modified. The Compound Poisson process is replaced with a more general renewal risk process with interoccurrence times of Erlangian type. We focus our analysis on the probability that the process of surplus reaches a certain level before ruin occurs, χ(u,b). Our main contribution is the generalization obtained in the computation of χ(u,b) for the case of interoccurrence time between claims distributed as Erlang(2, β) and the individual claim amount as Erlang (n, γ).Peer Reviewe

School violence and self-image in adolescents from the region of Murcia (Spain)

Esta investigación pretende estudiar los niveles de violencia percibida y sufrida en centros escolares, analizar la satisfacción con la autoimagen corporal y la relación entre estas variables. Es un estudio descriptivo cuya muestra está compuesta por 284 escolares de la Región de Murcia con edades comprendidas entre los 12 y 17 años. Se han administrado los cuestionarios BODY SHAPE self-perceived de Stunkard, Sorensen y Schulsinger (1983) para el análisis de la autoimagen corporal y el CUVECO de Fernández-Baenal et al. (2011) para la violencia escolar. Los resultados muestran, sobre la imagen corporal, que existe un elevado porcentaje de adolescentes que están insatisfechos, especialmente las chicas, mientras que sobre la violencia escolar se observa una estabilidad en la evolución de violencia percibida mientras que se produce una disminución de la violencia sufrida. Por último, se ha registrado el mayor riesgo de formar parte de los grupos que más violencia sufren entre quienes mayor descontento muestran con su autoimagenThis investigation aims to study perceived violence and suffered violence levels in school settings, to analyze satisfaction with body self-image and to explore the relationship among these variables. It is a descriptive study whose sample is made up of 284 secondary students from the Region of Murcia aged 12 to 17. BODY SHAPE self-perceived questionnaire by Stunkard, Sorensen and Schulsinger (1983) and CUVECO questionnaire by Fernández-Baenal et al. (2011) were administered to analyze body self-image and school violence respectively. With regard to their body image the results show that there is a high percentage of students who are dissatisfied, especially girls. Regarding school violence levels, students’ perceived violence is stable while suffered violence decreases progressively. Finally, if students are dissatisfied there is a higher chance of belonging to groups who suffered more violenc

Implementation of an autonomy support program during Physical Education lessons

El objetivo de este estudio es conocer los efectos de un programa basado en el soporte de autonomía a través de las clases de Educación Física sobre las necesidades psicológicas básicas, la regulación conductual y la percepción del estilo interpersonal del docente. Los participantes del estudio fueron 61 alumnos (25 chicos y 36 chicas) con edades comprendidas entre los 14 y los 17 años de edad (M = 14.97; DT = .85), pertenecientes a dos Centros Educativos españoles. Los estudiantes fueron divididos aleatoriamente en dos grupos (control y experimental). Los instrumentos utilizados fueron la Escala de Satisfacción de Necesidades Psicológicas Básicas, el Cuestionario de la Regulación Conductual en el Deporte y el Cuestionario de Estilo interpersonal del docente. Los profesores aplicaron en el grupo experimental el programa basado en el soporte de autonomía durante las clases de Educación Física en un total de ocho semanas. Los resultados indicaron diferencias estadísticamente significativas respecto a la relación con los demás (p<.01) y a la percepción del estilo autónomo del docente (p<.05), no encontrándose diferencias significativas respecto al resto de variables. Como conclusión principal indicar que un programa basado en el fomento de la autonomía, puede ser óptimo para el incremento de las relaciones entre los alumnos

Non-parametric analysis of the rest-frame UV sizes and morphological disturbance amongst L* galaxies at 4<z<8

We present the results of a study investigating the sizes and morphologies of redshift 4 < z < 8 galaxies in the CANDELS GOODS-S, HUDF and HUDF parallel fields. Based on non-parametric measurements and incorporating a careful treatment of measurement biases, we quantify the typical size of galaxies at each redshift as the peak of the log-normal size distribution, rather than the arithmetic mean size. Parameterizing the evolution of galaxy half-light radius as $r_{50} \propto (1+z)^n$, we find $n = -0.20 \pm 0.26$ at bright UV-luminosities ($0.3L_{*(z=3)} < L < L_*$) and $n = -0.47 \pm 0.62$ at faint luminosities ($0.12L_* < L < 0.3L_*$). Furthermore, simulations based on artificially redshifting our z~4 galaxy sample show that we cannot reject the null hypothesis of no size evolution. We show that this result is caused by a combination of the size-dependent completeness of high-redshift galaxy samples and the underestimation of the sizes of the largest galaxies at a given epoch. To explore the evolution of galaxy morphology we first compare asymmetry measurements to those from a large sample of simulated single S\'ersic profiles, in order to robustly categorise galaxies as either `smooth' or `disturbed'. Comparing the disturbed fraction amongst bright ($M_{UV} \leq -20$) galaxies at each redshift to that obtained by artificially redshifting our z~4 galaxy sample, while carefully matching the size and UV-luminosity distributions, we find no clear evidence for evolution in galaxy morphology over the redshift interval 4 < z < 8. Therefore, based on our results, a bright ($M_{UV} \leq -20$) galaxy at z~6 is no more likely to be measured as `disturbed' than a comparable galaxy at z~4, given the current observational constraints.Comment: 29 pages, 25 figures, 4 tables, published in MNRA

Differences in forms of organization of the padel lessons with students

El objetivo del presente estudio es conocer los efectos en la cantidad y eficacia de golpeos y la percepción de satisfacción/diversión, aburrimiento y esfuerzo a través de cuatro formas de organización diferentes de sesiones de pádel. Los participantes del estudio fueron 48 estudiantes del Ciclo Formativo de Técnico en Animación y Actividades Físico Deportivas (33 chicos y 15 chicas), con edades comprendidas entre los 18 y los 26 años. Se evaluó la cantidad y eficacia de los golpeos a través de una hoja de observación directa. La percepción de diversión y aburrimiento fue evaluada a través del Sport Satisfaction Instrument y la percepción de esfuerzo a través de la Pictorial Children´s Effort Rating Table. Los resultados obtenidos muestran que la forma de organización basada en el peloteo entre los alumnos se plantea como la más eficaz en la enseñanza del pádel, obteniendo un número significativamente mayor y más eficaz de golpeos, así como valores significativamente superiores de diversión/satisfacción y esfuerzo e inferiores de aburrimientoThe aim of this study was to determine the effects on the quantity and effectiveness of strokes and perceived satisfaction / fun, boredom and effort through four different organizational forms of paddle sessions. Study participants were 48 students from the Technical Training Course in Animation and Sports Physical Activities (33 boys and 15 girls) with ages between 18 and 26 years. The amount and effectiveness of beatings through direct observation of a sheet was evaluated. The perception of fun and boredom was evaluated through the Sport Satisfaction Instrument and perception of effort through the Pictorial Children's Effort Rating Table. The results show that the form of organization based on the rally among students is seen as the most effective in teaching paddle. A significantly greater and more effective number of strokes and significantly higher values of amusement / satisfaction and effort and lower boredom have been proved as a result of this form of organizatio

Sub-400 nm film thickness determination from transmission spectra in organic distributed feedback lasers fabrication

The design and fabrication of thin-film based organic optoelectronic devices require knowledge of the film optical properties. A low-cost and non-destructive method often used for optical characterization of films is the well-established spectrophotometric envelope method. However, this method is typically limited to thickness above 400 nm, a value often higher than that of the films involved in these devices. This paper studies a procedure to obtain the thickness of sub-400 nm active films from their spectrophotometric trace when the refractive index is previously known. The proposed procedure is based on comparing the experimental transmission spectrum in the transparent spectral window with that obtained by simulation. The capabilities of the proposed method are demonstrated here by its application in the fabrication of organic distributed feedback lasers, for which a fine control of film thickness is important to obtain an optimized and reproducible response. Results are verified with other techniques, such as ellipsometry and profilometry. Thus, with the proposed method, film thickness can be easily determined down to 40 nm maintaining an accuracy of about 5 nm even for films with low refractive index (1.5–1.7). Different methods to determine refractive index of these films are also discussed.Spanish Ministry of Economy and Competitivity (MINECO) and European Community (FEDER) through grant no. MAT2015-66586-R

SHARDS: Constraints on the dust attenuation law of star-forming galaxies at z~2

We make use of SHARDS, an ultra-deep (<26.5AB) galaxy survey that provides optical photo-spectra at resolution R~50, via medium band filters (FWHM~150A). This dataset is combined with ancillary optical and NIR fluxes to constrain the dust attenuation law in the rest-frame NUV region of star-forming galaxies within the redshift window 1.5<z<3. We focus on the NUV bump strength (B) and the total-to-selective extinction ratio (Rv), targeting a sample of 1,753 galaxies. By comparing the data with a set of population synthesis models coupled to a parametric dust attenuation law, we constrain Rv and B, as well as the colour excess, E(B-V). We find a correlation between Rv and B, that can be interpreted either as a result of the grain size distribution, or a variation of the dust geometry among galaxies. According to the former, small dust grains are associated with a stronger NUV bump. The latter would lead to a range of clumpiness in the distribution of dust within the interstellar medium of star-forming galaxies. The observed wide range of NUV bump strengths can lead to a systematic in the interpretation of the UV slope ($\beta$) typically used to characterize the dust content. In this study we quantify these variations, concluding that the effects are $\Delta\beta$~0.4.Comment: 13 pages, 11+2 figures, 3 tables. MNRAS, in pres

Simultaneous Determination of Refractive Index and Thickness of Submicron Optical Polymer Films from Transmission Spectra

High-transparency polymers, called optical polymers (OPs), are used in many thin-film devices, for which the knowledge of film thickness (h) and refractive index (n) is generally required. Spectrophotometry is a cost-effective, simple and fast non-destructive method often used to determine these parameters simultaneously, but its application is limited to films where h > 500 nm. Here, a simple spectrophotometric method is reported to obtain simultaneously the n and h of a sub-micron OP film (down to values of a few tenths of a nm) from its transmission spectrum. The method is valid for any OP where the n dispersion curve follows a two-coefficient Cauchy function and complies with a certain equation involving n at two different wavelengths. Remarkably, such an equation is determined through the analysis of n data for a wide set of commercial OPs, and its general validity is demonstrated. Films of various OPs (pristine or doped with fluorescent compounds), typically used in applications such as thin-film organic lasers, are prepared, and n and h are simultaneously determined with the proposed procedure. The success of the method is confirmed with variable-angle spectroscopic ellipsometry.Spanish Ministry of Economy and Competitivity (MINECO) and European Community (FEDER) through grant no. MAT2015-66586-R

Aplicación de un programa basado en el soporte de autonomía en las clases de Educación Física

The purpose of this study is to know the effects of a autonomy support program through the Physical Education lessons on the psychological needs satisfaction, behavioral regulation and teacher interpersonal style. Sample were 61 students (25 boys and 36 girls) aged between 14 and 17 years (M = 14.97; DT = .85), belonging to two educational centres in Spain. Students were randomly divided In two groups (control and experimental). The instruments used were the Basic Psychological Needs Satisfaction Scale, the Behavioral Regulation Questionnaire in Sport and the Interpersonal Teacher Style Questionnaire. The teachers applied in the experimental group the autonomy support program during the Physical Education lessons in a total of eight weeks. The results showed statistically significant differences regarding the relation with the others (p&lt;.01) and the perception of teacher autonomous style (p&lt;.05), not finding significant differences with respect to the other variables. As a main conclusion to indicate that a program based on the promotion of autonomy may be optimal for the increase relations between students.El objetivo de este estudio es conocer los efectos de un programa basado en el soporte de autonomía a través de las clases de Educación Física sobre las necesidades psicológicas básicas, la regulación conductual y la percepción del estilo interpersonal del docente. Los participantes del estudio fueron 61 alumnos (25 chicos y 36 chicas) con edades comprendidas entre los 14 y los 17 años de edad (M = 14.97; DT = .85), pertenecientes a dos Centros Educativos españoles. Los estudiantes fueron divididos aleatoriamente en dos grupos (control y experimental). Los instrumentos utilizados fueron la Escala de Satisfacción de Necesidades Psicológicas Básicas, el Cuestionario de la Regulación Conductual en el Deporte y el Cuestionario de Estilo interpersonal del docente. Los profesores aplicaron en el grupo experimental el programa basado en el soporte de autonomía durante las clases de Educación Física en un total de ocho semanas. Los resultados indicaron diferencias estadísticamente significativas respecto a la relación con los demás (p&lt;.01) y a la percepción del estilo autónomo del docente (p&lt;.05), no encontrándose diferencias significativas respecto al resto de variables. Como conclusión principal indicar que un programa basado en el fomento de la autonomía, puede ser óptimo para el incremento de las relaciones entre los alumnos.ABSTRACTThe purpose of this study is to know the effects of a autonomy support program through the Physical Education lessons on the psychological needs satisfaction, behavioral regulation and teacher interpersonal style. Sample were 61 students (25 boys and 36 girls) aged between 14 and 17 years (M = 14.97; DT = .85), belonging to two educational centres in Spain. Students were randomly divided In two groups (control and experimental). The instruments used were the Basic Psychological Needs Satisfaction Scale, the Behavioral Regulation Questionnaire in Sport and the Interpersonal Teacher Style Questionnaire. The teachers applied in the experimental group the autonomy support program during the Physical Education lessons in a total of eight weeks. The results showed statistically significant differences regarding the relation with the others (p&lt;.01) and the perception of teacher autonomous style (p&lt;.05), not finding significant differences with respect to the other variables. As a main conclusion to indicate that a program based on the promotion of autonomy may be optimal for the increase relations between students