A Guide for Children: Let\u27s Prepare for the Asylum Screening

Senior Project submitted to The Division of Social Studies of Bard College

Meandering periods and asymmetries in light curves of Miras: Observational evidence for low mass-loss rates

Some Miras -- long-period variables in late evolutionary stages -- have meandering pulsation periods and light curve asymmetries, the causes of which are still unclear. We aim to understand better the origin of these phenomena by investigating a sample of solar-neighbourhood Miras. We characterised this group of stars and related their variability characteristics to other stellar parameters. We analysed observations from several databases to obtain light curves with maximum time span and temporal coverage for a sample of 548 Miras. We determined their pulsation period evolution over a time span of many decades, searched for changes in the periods, and determined the amplitude of the period change. We also analysed the Fourier spectra with respect to possible secondary frequency maxima. The sample was divided into two groups with respect to the presence of light curve bumps. IR colours and indicators of the third dredge-up were collected to study the sample stars' mass-loss and deep mixing properties. Our analysis revealed one new star, T~Lyn, with a continuously changing period. The group of Miras with meandering period changes is exclusively made up of M-type stars. The Fourier spectra of the meandering period Miras have no prominent additional peaks, suggesting that additional pulsation modes are not the cause of the meandering periods. We confirm that bumps are more common among S and C Miras and show, for the first time, that Miras with bumps have lower mass-loss rates than those with regular, symmetric light curves. Also Miras with meandering period changes have relatively little mass loss. We conclude that Miras with strongly changing periods or asymmetries in their light curves have relatively low dust mass-loss rates. Meandering period changes and light curve asymmetries could be connected to He-shell flashes and third dredge-up episodes.Comment: 13 pages (plus 13 pages Appendix), 14 Figures, accepted for publication in A&

La colección herpetológica de Bolivia depositada en la Estación Biológica de Doñana

The collection consists of 822 specimens, of which 529 are amphibians, all of them anurans (5 families, 17 genera and 51 species) and 293 specimens are reptiles (10 families, 28 genera and 49 species). The collection has around 25% of the amphibians species known to occur in Bolivia and about 19% of the reptile species. They come from 55 localities of the Bolivian Departments of Beni, Chuquisaca, Cochabamba, La Paz, Potosí and Santa Cruz and represent the following bioregions: Puna, Chaco, Chiquitanian Forest, Wet Savannas, Ceja de Montaña, Yungas, Interandean Dry Valleys and Humid Lowland Forest. The specimens of Scinax chiquitanus and Phrynopus kempffi are paratypes. The record of Pleurodema borelli is the first for the Santa Cruz Department and second for Bolivia. Liolaemus dorbignyi also constitutes the second report for the country and Tropidurus melanopleurus is cited for the first time for the Beni Department.La colección se compone de 822 ejemplares, 529 anfibios y 293 reptiles. Los anfibios son todos anuros, pertenecientes a 51 especies de 17 géneros y cinco familias. Los reptiles estan representados por 49 especies, incluidas en 28 géneros de 10 familias. Los ejemplares provienen de 55 localidades repartidas en los Departamentos bolivianos de Beni, Chuquisaca, Cochabamba, La Paz, Potosí y Santa Cruz, y representan las siguientes bioregiones: Puna, Chaco, Bosque Chiquitano, Sabanas Húmedas, Ceja de Montaña, Yungas, Valles Secos Interandinos y Bosque Húmedo de Llanura. Los ejemplares de Scinax chiquitanus y Phrynopus kempffi son paratipos. Pleurodema borelli es citada por primera vez para el Departamento de Santa Cruz y por segunda vez para Bolivia; también el registro de Liolaemus dorbignyi constituye el segundo para el país y el de Tropidurus melanopleurus el primero para el Departamento Beni

Early warning system based on data mining to identify crime patterns

The analysis of criminal information is critical for the purpose of preventing the occurrence of offenses, so the crime records committed in the past are analyzed including perpetrators. The main objective was to identify crime patterns in the city of Bogota, Colombia, supported using Early Warning System based on data mining (CRISP-DM method). The research results show the identification of 12 different criminal profiles demonstrating that the Early Warning System is applicable since it managed to significantly reduce the time devoted to the processes of registering complaints and searching for criminal profiles.Universidad Peruana de Ciencias Aplicadas, Universidad de la Costa, Corporación Universitaria Latinoamericana

On the weak lensing masses of a new sample of galaxy groups

Galaxy group masses are important to relate these systems with the dark matter halo hosts. However, deriving accurate mass estimates is particularly challenging for low-mass galaxy groups. Moreover, calibration of observational mass-proxies using weak-lensing estimates have been mainly focused on massive clusters. We present here a study of halo masses for a sample of galaxy groups identified according to a spectroscopic catalogue, spanning a wide mass range. The main motivation of our analysis is to assess mass estimates provided by the galaxy group catalogue derived through an abundance matching luminosity technique. We derive total halo mass estimates according to a stacking weak-lensing analysis. Our study allows to test the accuracy of mass estimates based on this technique as a proxy for the halo masses of large group samples. Lensing profiles are computed combining the groups in different bins of abundance matching mass, richness, and redshift. Fitted lensing masses correlate with the masses obtained from abundance matching. However, when considering groups in the low-and intermediate-mass ranges, masses computed according to the characteristic group luminosity tend to predict higher values than the determined by the weak-lensing analysis. The agreement improves for the low-mass range if the groups selected have a central early-Type galaxy. Presented results validate the use of mass estimates based on abundance matching techniques, which provide good proxies to the halo host mass in a wide mass range.Fil: Gonzalez, Elizabeth Johana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentina. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Rodriguez, Facundo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Merchan, Manuel Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Garcia Lambas, Diego Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Makler, Martín. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología. Centro Internacional de Estudios Avanzados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Físicas. - Universidad Nacional de San Martín. Instituto de Ciencias Físicas; Argentina. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Chalela, Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Pereira, Maria E. S.. University of Michigan. Department of Physics; Estados UnidosFil: Moraes, Bruno. Universidade Federal do Rio de Janeiro; BrasilFil: Shan, HuanYuan. Chinese Academy of Sciences; República de China. Shanghai Astronomical Observatory; Chin