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- ItemA robust DPG method for large domains(2021) Führer, Thomas; Heuer, NorbertWe observe a dramatic lack of robustness of the DPG method when solving problems on large domains and where stability is based on a Poincare-type inequality. We show how robustness can be re-established by using appropriately scaled test norms. As model cases we study the Poisson problem and the Kirchhoff-Love plate bending model, and also include fully discrete variants where optimal test functions are approximated. Numerical experiments for both model problems, including an-isotropic domains and mixed boundary conditions, confirm our findings.
- ItemA simple analytical model for a fast 3D assessment of peripheral photon dose during coplanar isocentric photon radiotherapy(2022) Sánchez Nieto, Beatriz; López Martínez, Ignacio N.; Rodríguez Mongua, José Luis; Espinoza Bornscheuer, Ignacio GuillermoConsidering that cancer survival rates have been growing and that nearly two-thirds of those survivors were exposed to clinical radiation during its treatment, the study of long-term radiation effects, especially secondary cancer induction, has become increasingly important. To correctly assess this risk, knowing the dose to out-of-field organs is essential. As it has been reported, commercial treatment planning systems do not accurately calculate the dose far away from the border of the field; analytical dose estimation models may help this purpose. In this work, the development and validation of a new three-dimensional (3D) analytical model to assess the photon peripheral dose during radiotherapy is presented. It needs only two treatment-specific input parameter values, plus information about the linac-specific leakage, when available. It is easy to use and generates 3D whole-body dose distributions and, particularly, the dose to out-of-field organs (as dose–volume histograms) outside the 5% isodose for any isocentric treatment using coplanar beams [including intensity modulated radiotherapy and volumetric modulated arc therapy (VMAT)]. The model was configured with the corresponding Monte Carlo simulation of the peripheral absorbed dose for a 6 MV abdomen treatment on the International Comission on Radiological Protection (ICRP) 110 computational phantom. It was then validated with experimental measurements using thermoluminescent dosimeters in the male ATOM anthropomorphic phantom irradiated with a VMAT treatment for prostate cancer. Additionally, its performance was challenged by applying it to a lung radiotherapy treatment very different from the one used for training. The model agreed well with measurements and simulated dose values. A graphical user interface was developed as a first step to making this work more approachable to a daily clinical application.
- ItemA Survey on Deep Learning and Explainability for Automatic Report Generation from Medical Images(2022) Messina, Pablo; Pino, Pablo; Parra Santander, Denis; Soto Arriaza, Álvaro Marcelo; Besa, Cecilia; Uribe Arancibia, Sergio A.; Andía Kohnenkampf, Marcelo Edgardo; Tejos Núñez, Cristián Andrés; Prieto Vásquez, Claudia; Capurro, Daniel
- ItemAdmiramos la foto de un hombre blanco. Entrada y salida del racismo en Chile según Perro Bomba(2023) Sepúlveda Eriz Magda; Departamento de Humanidades de la Universidad Andrés BelloLa película Perro bomba (2019) representa cómo el racismo entra en el discurso social y cómo un afectado puede huir de la discriminación. El protagonista discute el régimen de visibilidad etnocéntrico, pues postula que la fotografía con imágenes de blancos ha desempeñado un papel importante en el racismo. A su vez, la secuencia narrativa marca la discriminación chilena y haitiana, las que terminan arrojando al personaje principal a una casa okupa, donde existe realmente una comunidad, que no teme enfrentarse a las leyes del país y que se constituye en el único refugio frente al racismo. La película no solo representa esta salida al racismo, sino, además, ella misma no es racista en tanto expone y valora el patrimonio haitiano en Chile. En relación con el patrimonio, la sonoridad de la película nos hace escuchar el creole y la música haitiana y, respecto de la imagen, nos permite visualizar otras formas de autorrepresentación física, donde las trenzas y los bailes son parte central de la belleza. Dado este levantamiento del patrimonio, el filme no solo convierte la migración en un tema, sino que ella misma hace migrar los significantes sonoros y visuales del cine chileno hacia las materialidades haitianas en Chile.
- ItemAlma aristotélica e mente contemporânea: divergências e convergências de um problema difícil(Editora Fi, 2022) Boeri, Marcelo D.
- ItemAnalysis of Backward Euler Primal DPG Methods(2021) Führer, Thomas; Heuer, Norbert; Karkulik, MichaelWe analyze backward Euler time stepping schemes for a primal DPG formulation of a class of parabolic problems. Optimal error estimates are shown in a natural norm and in the L-2 norm of the field variable. For the heat equation the solution of our primal DPG formulation equals the solution of a standard Galerkin scheme and, thus, optimal error bounds are found in the literature. In the presence of advection and reaction terms, however, the latter identity is not valid anymore and the analysis of optimal error bounds requires to resort to elliptic projection operators. It is essential that these operators be projections with respect to the spatial part of the PDE, as in standard Galerkin schemes, and not with respect to the full PDE at a time step, as done previously.
- ItemAnalyzing regional and local changes in irradiance during the 2019 total solar eclipse in Chile, using field observations and analytical modeling(MDPI, 2021) Castillejo Cuberos, Armando; Cardemil Iglesias, José Miguel; Escobar Moragas, RodrigoSolar eclipses are astronomic phenomena in which the Earth’s moon transits between the planet and the Sun, projecting a shadow onto the planet’s surface. As solar power installed capacity increases, detailed studies of this region-wide phenomenon’s effect in irradiance is of interest; how-ever, the literature mainly reports its effects on localized scales. A measurement campaign spanning over 1400 km was pursued for the 2 July 2019 total solar eclipse in Chile, to register the event and establish a modeling framework to assess solar eclipse effects in irradiance over wide regional scales. This work describes the event and presents an estimation framework to decompose atmospheric and eclipse effects on irradiance. An analytical model was applied to study irradiance attenuation throughout the Chilean mainland territory, using satellite-derived and astronomical data as inputs compared to ground measurements in eight stations. Results showed good agreement between model and observations, with Mean Bias Errors of −0.008 to 0.98 W/m2 for Global Horizontal Irradiance and −0.004 to −4.664 W/m2 for Direct Normal Irradiance, with Normalized Root Mean Squared Errors of 0.7–5.8% and 1.4–12.2%, respectively. Energy losses due to obscuration corre-sponded between 20–40% for Global Horizontal Irradiance and 25–50% for Direct Normal Irradi-ance over Chilean territory.
- ItemArchivo Fílmico UC: Aproximaciones a la representación audiovisual universitaria 1964-1977Foxley, Susana; Urrutia Neno, Carolina; Vergara, XimenaSomos una colección de contenidos audiovisuales gratuitos, creados por alumnos y profesores de los centros de formación Instituto Fílmico, Escuela de Arte de la Comunicación y Dirección Audiovisual de la Pontificia Universidad Católica de Chile. Somos un archivo vivo que almacena cuatro décadas de producciones disponibles para ti: estudiante, profesor, creador, investigador y amante del audiovisual chileno.
- ItemAre the school choices of indigenous students affected by discrimination? Evidence from Chile(2023) Hofflinger, Álvaro; Villalobos, Cristóbal; Cárdenas, Loreto; Treviño Villarreal, Juan ErnestoA common criticisms of school choice programs is that, instead of improving student achievement, they would increase school segregation. Parents may use different criteria to choose a school, such as proximity, school quality, or the school's ethnic/racial composition. As a result, the system would be segregated based on the parent's preferences. This research examines the school preferences of indigenous parents and whether ethnic discrimination influences their decision-making process. Longitudinal national-level data from Chile were analyzed using OLS with fixed effects. The results show that indigenous students, particularly those who have suffered ethnic discrimination in middle school, prefer high schools with a higher percentage of indigenous students. Furthermore, it was found that the level of acts of discrimination occurring in middle schools increases as the percentage of indigenous students rises. However, when the proportion of indigenous and non-indigenous students is similar, indigenous students are less likely to face discrimination.
- ItemArgumentative orchestration in the mathematical modelling cycle in the classroom(2022) Solar Bezmalinovic, Horacio; Ortiz, Andrés; Arriagada Jofre, Victoria Paz; Deulofeu, Jordi; Universidad Católica de la Santísima Concepción; Universidad Autónoma de Barcelona; UCGiven the importance of modelling in mathematics classrooms, and despite the extensive body of research on teacher support for promoting the mathematical modelling cycle in the classroom, authors have overlooked how teacher support for argumentation can contribute to this cycle. This study is aimed at characterizing teacher support for argumentation in the mathematical modelling cycle in the classroom. We analyzed 10 class episodes taken from the cases of two teachers, Soledad and Ángeles. The episodes were analyzed considering teacher support for argumentative orchestration (communicative strategies and pattern recognition). In the two cases studied, we found that argumentative orchestration exhibited different types of overall presence and recurrence throughout the stages of the mathematical modelling cycle, with communicative strategies being more present across the board and more recurrent in the mathematical modelling cycle than pattern recognition strategies
- ItemAssessment of Early Childhood Mental Health in Immigrant and Local Children in Chile(2022) Narea Biscupovich, Marigen Soledad; Caqueo Urízar, Alejandra; Torres Irribarra, David; Treviño Villarreal, Juan Ernesto; Flores, Jerome; Gutiérrez Rioseco, JavieraLittle is known about mental health during early childhood and differences in mental health problems between migrant and local preschool children in Chile. This research aimed to study the early mental health of children and disparities in mental health indicators between immigrant and local children in the context of a middle-income country. Parents and teachers assessed immigrant (n = 120) and non-immigrant (n = 383) children between 3 and 4 years old with the Sistema de Evaluación de Niños y Adolescentes (Child and Adolescent Evaluation System, SENA). A multivariate analysis of covariance (MANCOVA) was used to study both main and interaction effects while controlling for the clustering of children on center-based care. Results show that immigrant parents tended to report more internalizing problems than locals’ parents did in terms of depression, anxiety, and somatic complaints. Also, they reported more attention problems, developmental delay, unusual behavior, rigidity, and isolation in immigrant children. However, teachers’ assessments regarding immigrant children were similar to non-immigrant children’s evaluations in many cases. Finally, girls presented fewer emotional and behavioral problems than boys. Our study shows the importance of assessing mental health during early childhood, especially in immigrant children, and the difficulty of carrying out this evaluation through different information sources from parents and early childhood teachers.
- ItemCaracterización sobre explicaciones de docentes en servicio acerca de la noción científica de disolución(2022) Quintanilla Gatica, Mario R.; Mercado Baeza, Marcelo EduardoEn este trabajo presentamos y discutimos las directrices teóricas y metodológicas de una experiencia experimental con profesorado de ciencias en ejercicio de diferentes establecimientos educacionales de Chile, que tuvo por finalidad identificar y caracterizar las explicaciones sobre el modelo de disolución a partir de la elaboración de narrativas personales. Ello durante un curso de desarrollo profesional docente en el que se propició la reflexión sobre la relevancia del lenguaje en la interpretación de los fenómenos experimentales. Los resultados dejan en evidencia la coexistencia de tipologías diversas de explicación científica en tres niveles: el microscópico, el macroscópico y el simbólico, que se expresa en la emergencia de cuatro perfiles explicativos sobre el fenómeno de la disolución., lo que se debería en parte a la diversidad del profesorado que participó en el estudio, conocimiento restringido de la relevancia del lenguaje para comunicar ideas científicas y un acentuado énfasis en los procesos descriptivos y microscópicos acerca de las disoluciones.
- ItemCHAIRS: A choice-based air transport simulator applied to airline competition and revenue management(2022) Fukushi Estay, Mitsuyoshi Andres; Delgado Breinbauer, Felipe Alberto; Raveau Feliú, Sebastián; Santos, Bruno F.In Revenue Management (RM) systems, information censoring and the interaction between the forecasting and optimization stages, increases the costs and complexity of performance analysis using historical data. An affordable and suitable alternative is using simulations, but appropriate behavioral models must be considered. In the following document, we discuss and test the implementation of a dynamic air transport market simulator, designed to analyze RM systems. The simulator replicates the behavior of passengers that book seats offered in multiple flights by different airlines. We use discrete choice models to replicate the demand behavior, accounting for preferences and decision rule heterogeneity, and including a temporal evolution of the preference throughout the selling horizon. To replicate the supply behavior, a number of airlines modify the price and quantity of different fare classes offered in each flight, using a variety of RM forecasting, un-constraining, and optimization techniques. The simulator allows analysts to study the economic benefit of RM systems under predefined assumptions in an artificial and controlled environment. This increases the benefits obtained by the correct selection of context-appropriate RM systems and the likelihood of successfully implementing new and complex systems. We test and showcase the simulator performance, studying the entrance of a new airline in a competitive context. We generate, implement and evaluate different RM strategies in response to the introduction of new competition, and discuss the results, highlighting the interpretability and accuracy of the proposed framework.
- ItemChilean EFL student teachers and social justice: ambiguity and uncertainties in understanding their professional pedagogical responsibility(2022) Barahona, Malba; Ibaceta Quijanes, XimenaProfessional pedagogical responsibility (PPR) for teachers does not only mean to meet deadlines or attend meetings, but also to be conscious of how their actions can contribute to challenging inequities in society. Thus, it is imperative that teachers of English embrace the responsibility of teaching English as a tool to promote social justice. This article reports on a qualitative study to understand how seven pre-service teachers developed a sense of PPR and to what extent participants' discourse revealed a sense of social justice. Data were collected through a number of semi-structured interviews that required participants to reflect on different practicum experiences and expectations for their future work as teachers of English. The results demonstrated different degrees of PPR ranging from resistance to high levels of agency. These different degrees were shaped by personal drives such as preservice teachers' motives for teaching English, but also by social and contextual factors such as expectations and requirements of the practicum. The outcomes also suggested that most preservice teachers were unaware of their role as change agents. The paper concludes with implications on how the integration of a social justice perspective in initial English language teacher education programmes can strengthen their professional responsibility.
- ItemChilean University Students’ Digital Learning Technology Usage Patterns and Approaches to Learning(2022) González Ugalde, Carlos Hugo; López, Dany; Calle Arango, Lina; Montenegro, Helena; Clasing, PaulaPurpose: This study aims to explore Chilean students’ digital technology usage patterns and approaches to learning. Design/Approach/Methods: We conducted this study in two stages. We worked with one semester learning management systems (LMS), library, and students’ records data in the first one. We performed a k-means cluster analysis to identify groups with similar usage patterns. In the second stage, we invited students from emerging clusters to participate in group interviews. Thematic analysis was employed to analyze them. Findings: Three groups were identified: 1) Digital library users/high performers, who adopted deeper approaches to learning, obtained higher marks, and used learning resources to integrate materials and expand understanding; 2) LMS and physical library users/mid-performers, who adopted mainly strategic approaches, obtained marks close to average, and used learning resources for studying in an organized manner to get good marks; and 3) Lower users of LMS and library/mid-low performers, who adopted mainly a surface approach, obtained mid-to-lower-than-average marks, and used learning resources for minimum content understanding. Originality/Value: We demonstrated the importance of combining learning analytics data with qualitative methods to make sense of digital technology usage patterns: approaches to learning are associated with learning resources use. Practical recommendations are presented.
- ItemCicero and his Clamorous Silences: Was he fair enough with the Epicureans and their Ethical and Political Views?(2022) Aoiz, Javier; Boeri, Marcelo D.If our knowledge of Epicurean philosophy depended exclusively upon the information conveyed by their adversaries, we would be practically unaware of the political component of the Epicurean study of nature (φυσιολογία), and of the political considerations that grounded the Epicurean way of life. This paper shows how Cicero omits some elements of Epicureanism that are crucial to understanding how political reflection was integrated into Epicurean philosophy. We argue that Cicero consciously omits important details of Epicurean arguments regarding ethics and politics and includes some silences that can be described as «clamorous». By bypassing the crucial interconnection between political theory and the Epicurean study of nature, Cicero includes passing reference to Epicurean contractualism and he does not set out the Epicurean theoretical framework in which it was originally inscribed.
- ItemClimate change impacts on invasive potential of pink hibiscus mealybug, Maconellicoccus hirsutus (Green), in Chile(2013) Jara Contreras, Valentina Isabel; Meza, Francisco Javier; Zaviezo Palacios, Tania; Chorbadjian Alonso, Rodrigo ArmenMaconellicoccus hirsutus (Green) (Hemiptera: Pseudoccidae) is an important pest in many countries being responsible for considerable economic loses. Although it is not currently present in Chile, the chance that it could be accidentally introduced rises with the list of infested countries increasing over the last years. In addition, climate change projections indicate that a larger region would fit as potential habitat for this pest, allowing it to persist over time and colonize a larger proportion of the Chilean territory. In this study the geographic distribution and the number of generations this mealybug would develop in Chile were determined, under current temperatures and under two projected climatic scenarios. Cumulative degree days were calculated for current and future scenarios using a lower temperature threshold of 14.5 degrees C, with 624.5 degree-days as the thermal requirement for the species to complete one generation. The results show that under current climate conditions M. hirsutus could develop up to three generations in the north of the country (i.e. 18 degrees South) and one generation in the region near 37 degrees South. Under future scenarios' conditions the pest could develop up to five generations in the north, and one generation around the 42 degrees South. Present climate conditions in Chile would allow the establishment of the pink hibiscus mealybug, if the pest enters the country. Climate change conditions would allow the potentially invaded area to expand south, and would promote the development of more generations per year of the mealybug in the studied territory.
- ItemCoastal Wetlands: Ecosystems Affected by Urbanization?(2020) Rojas Quezada, Carolina Alejandra; Novoa, Vanessa; Rojas, Octavio; Ahumada-Rudolph, Ramón; Sáez, Katia; Fierro, Pablo; CEDEUS (Chile)Coastal wetlands are ecosystems that provide multiple benefits to human settlements; nonetheless, they are seriously threatened due to both a lack of planning instruments and human activities associated mainly with urban growth. An understanding of their functioning and status is crucial for their protection and conservation. Two wetlands with different degrees of urbanization, Rocuant-Andalién (highly urbanized) and Tubul-Raqui (with little urbanization), were analyzed using temperature, salinity, dissolved oxygen, pH, turbidity, granulometry, fecal coliform, and macroinvertebrate assemblage variables in summer and winter. In both wetlands marked seasonality in salinity, temperature and sediment texture classification, regulated by oceanic influence and changes in the freshwater budget, was observed. In the Rocuant-Andalién wetland, the increases in pH, dissolved oxygen, gravel percentage, and coliform concentration were statistically significant. Urbanization generated negative impacts on macroinvertebrate assemblage structure that inhabit the wetlands; greater richness and abundance (8.5 times greater) were recorded in the Tubul-Raqui wetland than in the more urbanized wetland. The multivariate statistical analysis reflects the alteration of these complex systems.
- ItemComercio informal en Santiago. Pistas etnográficas para el reconocimiento de una práctica urbana(2019) Matus Madrid, Christian; Montes Marín, MartínEl presente artículo constituye una reflexión sobre la persistencia del comercio informal como práctica urbana que forma parte relevante de la vida de los centros de las ciudades chilenas y latinoamericanas. Se fundamenta en una aproximación etnográfica al tema desarrollada por los autores en el marco de un estudio realizado en 2015 para el Ministerio de Economía, que tuvo como escenario la comuna de Santiago. En base a una metodología cualitativa, que combinó observaciones etnográficas, entrevistas semi-estructuradas y grupos de conversación con comerciantes informales y otros actores asociados, se indagó en las motivaciones que dan sentido al trabajo informal, y las múltiples estrategias con las que operan los comerciantes informales para eludir las políticas de control que los persiguen. Se plantea que un abordaje exitoso del comercio informal, por parte de la política pública, requiere de una comprensión integral de sus dimensiones económicas, históricasy culturales, que valore su aporte a la economía e impacto positivo en el espacio público. Como conclusión se propone establecer una estrategia de convivencia con el comercio informal, más que una política de control y represión, de modo de reconocer su aporte económico, social y cultural, haciéndolo partícipe del ordenamiento del espacio público.
- ItemComunicación visual a través de la portada del templo de San Francisco de La Paz(2023) Matas Musso, Josefina; Pérez V., Blanca Elvira; Mariaca Cardona, CristianEl estilo barroco mestizo o barroco del sur Andino es un estilo particular que se desarrolla en el altiplano de América del Sur y toma fuerzas en Bolivia en los actuales departamentos de La Paz, Oruro y Potosí. Uno de los mejores ejemplos de este estilo es la portada de San Francisco de La Paz que está constituida por tres partes claramente diferenciadas que se fueron alzando en el transcurso del tiempo. La portada retablo en su diseño y en su conjunto transmite un mensaje visual portador de las ideas evangelizadoras de los franciscanos en el siglo XVIII, con el paso del tiempo esa fachada, sigue dialogando con el paceño constituyéndose en un verdadero elemento comunicador de ideas.