El positivismo y las ciencias en el período finisecular del Chile decimonónico

Se analiza el aporte de la filosofía positivista a la ciencia nacional de fines del siglo xix en Chile, especialmente la contribución de sus principales exponentes: José Victorino Lastarria, los Hnos. Lagarrigue y Valentín Letelier entre otros; así como lWe analyze the contribution of the positivist philosophy to the national science at the end of the 19th Century in Chile, especially the work of its main exponents: José Victorino Lastarria, the Lagarrigue brothers, Valentín Letelier and others; as well

Neutron capture on ^{205}Tl: depicting the abundance pattern of lead isotopes in s-process nucleosynthesis

Proposal: Neutron capture on 205Tl: depicting the abundance pattern of lead isotopes in s-process nucleosynthesisWe propose to use the TOF technique to measure the neutron capture cross section of 205Tl(n,gamma) over the full energy range of stellar interest. An accurate measurement of this cross section is needed for a complete and consistent understanding of the s-process nucleosynthesis of the heaviest nuclei which are produced in low-mass and low metallicity AGB-stars. The only previous TOF measurement has yield only a partial information, insufficient for a reliable analysis of the complex branching pattern around 205Pb and 205Tl. Furthermore, there is also a discrepancy of 40% between the two previous activation measurements made at kT=24 keV. The cross section of 205Tl(n,gamma) is particularly relevant because it affects the equilibrium that is established in some stellar conditions between the 205Tl -> 205Pb bound-state Beta-decay and the 205Pb -> 205Tl E.C. decay. This effect induces a complex interplay which influences the final s-process abundance of both nuclei. We propose to measure accurately and with high resolution the 205Tl(n,gamma) cross section by using a set of four C6D6 detectors in combination with the pulsed neutron-source of CERN n_TOF.Preprin

A comparison between traditional monocular refraction and the biocular Humphriss technique

The standard approach for determining refractive error is monocular subjective refraction. In this technique the optometrist or ophthalmologist uses a phoropter to determine the endpoint at which the patient achieves best visual acuity (VA). The eye being tested is exposed to the VA chart, while the other eye is occluded. However, we view the world with two eyes (i.e., binocularly), and therefore a refraction technique conducted under binocular viewing conditions conceivably may yield more accurate results. Whereas several binocular refractive techniques exist including the Turville Infinity Balance and Vectographic Slide, they are used infrequently in standard clinical practice, and while included in optometric curriculum, are not emphasized and therefore rarely utilized by optometric students and recent optometric graduates. One such binocular technique is the Humphriss method, in which both eyes view the VA chart during refraction, but one eye (the eye not being actively tested) is defocused by a moderate degree. This creates a situation in which viewing is binocular such that focusing and eye alignment are determined by binocular perception. The technique is very quick, accurate and generally well-tolerated by the patient The purpose of this study is to conduct a systematic comparison of the binocular Humphriss technique to standard monocular refraction. The results will help determine the efficacy of the Humphriss technique, as well as providing clinical guidelines for application in optometric and ophthalmologic settings

Conocimiento de docentes de establecimientos escolares respecto a accidentes dentoalveolares en colegios de la comuna de Santiago Centro

Tesis (Cirujano Dentista)Introducción: La incidencia de traumatismos dentoalveolares (TDA) ha aumentado en los últimos años debido al cambio en los estilos de vida de las personas. Aproximadamente un tercio de la población ha sufrido algún TDA durante su vida y su relevancia trasciende en que tienden a ocurrir a una edad temprana. Actualmente son casi tan frecuentes como las consultas por caries en niños, y se piensa que en un futuro puedan tener una incidencia mayor. El manejo luego de uno de estos eventos debe ser realizado de manera ágil y con los conocimientos necesarios, ya que de la actitud inicial depende mayormente el pronóstico de una pieza dentaria. Por lo tanto, es importante que personas que más estén en contacto con niños tengan algún grado instrucción en este tema. Objetivo: Determinar el grado de conocimiento de profesores de escuelas de la comuna de Santiago frente a traumatismos dentales. Materiales y métodos: Se aplicó una encuesta segmentada en dos partes que contienen preguntas de caracterización de los participantes y de conocimiento ante el manejo de distintas situaciones de traumatismo dentoalveolar. Resultados: Del total de profesores encuestados un 85.7% indicaron que no saben o no conocen la existencia de protocolos frente a urgencias dentales en sus colegios, un 89% afirmó no haber recibido ningún grado de instrucción pese a que un 39.3% ha presenciado algún accidente dental en uno de sus estudiantes. Con respecto al conocimiento no hubo diferencias significativas por género (p>0,05). Caso contrario ocurre por años de experiencia laboral (p<0,05) y por tipo de dependencias en que imparten clases (p<0,05), donde si hubo diferencias significativas. El puntaje total de profesores promedió 8.4 puntos de respuestas correctas sobre 14 posibles. Conclusión: La falta de información y el conocimiento insuficiente de los profesores encuestados, refleja la necesidad de implementar programas educativos en los colegios para el manejo de urgencias dentales

The “Beta-Delayed Neutrons at RIKEN” project (BRIKEN): conquering the most exotic beta-delayed neutron-emitters

Among the main missions of modern radioactive isotope facilities is the exploration of properties of yet unknown isotopes on the neutron-rich side of the chart of nuclides. However, going more neutron-rich also means that the neutron separation energy decreases until it reaches the dripline at Sn = 0 MeV. If the neutron separation energy gets lower than the ß-decay energy window (Qß value), a new decay mechanism can occur: the emission of neutrons after ß-decay. These “ß-delayed neutron” (ßn) emitters play a crucial role in nuclear structure, nuclear astrophysics, and for nuclear reactor applications.Postprint (published version

Exploración de un Metodo de Gestión de Inventario para "Supermercados CUGAT"

73 p.En este trabajo lo que se busca es determinar un método de Gestión de Inventarios, que logre reducir los costos totales asignados a inventarios, garantizando una ruptura mínima de Stock. Para determinar el mejor método, se realizara un análisis de los procesos del Sistema encargado de determinar los montos y la cantidad optima de los pedidos de tres familias de productos de Supermercados Cugat, en la sucursal de San Vicente de Tagua Tagua. Con los datos contenidos en la Base de datos del Supermercados de estas tres familias de productos seleccionadas, se realiza una simulación de cinco método de Gestión de Inventarios. Se evalúan los distintos métodos y se selecciona el método que hubiese logrado el mejor equilibrio entre un bajo costo total de inventario y una mínima ruptura de Stock, durante el periodo de estudio

Optimized Dictionaries: A Semi-Automated Workflow of Concept Identification in Text-Data

Identifying social science concepts and measuring their prevalence and framing in text data has been a key task of scientists ever since. Whereas debates about text classifications typically contrast different approaches with each other, we propose a workflow that generates optimized dictionaries that are based on the complementary use of expert dictionaries, machine learning, and topic modeling. We demonstrate our case by identifying the concept of "territorial politics" in leading newspapers vis-à-vis parliamentary speeches in Spain (1976-2018) and the UK (1900-2018). We show that our optimized dictionaries outperform singular text-identification techniques with F1-scores around 0.9 for unseen data, even if the unseen data comes from a different political domain (media vs. parliaments). Optimized dictionaries have increasing returns and should be developed as a common good for researchers overcoming costly particularism

The BRIKEN Project: extensive measurements of ß-delayed neutron emitters for the astrophysical r process

An ambitious program to measure decay properties, primarily ß-delayed neutron emission probabilities and half-lives, for a significant number of nuclei near or on the path of the rapid neutron capture process, has been launched at the RIKEN Nishina Center. We give here an overview of the status of the project.Postprint (published version

Preliminary results on the 233U capture cross section and alpha ratio measured at n_TOF (CERN) with the fission tagging technique

233U is of key importance among the fissile nuclei in the Th-U fuel cycle. A particularity of 233U is its small neutron capture cross-section, which is on average about one order of magnitude lower than the fission cross-section.The accuracy in the measurement of the 233U capture cross-section depends crucially onan efficient capture-fission discrimination, thus a combined set-up of fission and ¿-detectors is needed. A measurement of the 233U capture cross-section and capture-to-fissionratio was performed at the CERN n_TOF facility. The Total Absorption Calorimeter (TAC) of n_TOF was employed as ¿-detector coupled with a novel compact ionization chamber as fission detector. A brief description of the experimental set-up will be given, and essential parts of the analysis procedure as well as the preliminary response of the set-up to capture are presented and discussedPostprint (published version