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A longitudinal approach for understanding algorithm use
(WILEY, 2022) Chacón Hiriart, Álvaro Marcelo; Kausel, Edgar E.; Reyes Torres Tomas Hernan
Research suggests that algorithms-based on artificial intelligence or linear regression models-make better predictions than humans in a wide range of domains. Several studies have examined the degree to which people use algorithms. However, these studies have been mostly cross-sectional and thus have failed to address the dynamic nature of algorithm use. In the present paper, we examined algorithm use with a novel longitudinal approach outside the lab. Specifically, we conducted two ecological momentary assessment studies in which 401 participants made financial predictions for 18 days in two tasks. Relying on the judge-advisor system framework, we examined how time interacted with advice source (human vs. algorithm) and advisor accuracy to predict advice taking. Our results showed that when the advice was inaccurate, people tended to use algorithm advice less than human advice across the period studied. Inaccurate algorithms were penalized logarithmically; the effect was initially strong but tended to fade over time. This suggests that first impressions are crucial and produce significant changes in advice taking at the beginning of the interaction, which later tends to stabilize as days go by. Therefore, inaccurate algorithms are more likely to accrue a negative reputation than inaccurate humans, even when having the same level of performance.
A robust DPG method for large domains
(2021) Führer, Thomas; Heuer, Norbert
We 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.
A 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 Guillermo
Considering 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.
A 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
Accessibility Indicators for the Geographical Assessment of Transport Planning in Latin-America Metropolitan Area
(MDPI, 2021) Martínez, Marcela ; Rojas Quezada, Carolina Alejandra; Condeço-Melhorado, Ana; Carrasco, Juan Antonio; CEDEUS (Chile)
Accessibility represents a key element in strengthening developed regions in terms of investment in transportation infrastructure. Accessibility is also an equity indicator to measure the ease with which a specific location achieves desired outcomes as well as the spillover effect; traditionally, these effects have been analyzed with econometric and engineering techniques, rather than from the perspective of geographical studies. The purpose of this research is to measure the spillover effects and the territorial cohesion of Infrastructure Regional Planning (PRI) for the Latin American metropolitan area of Concepción (MAC), Chile. To meet this purpose, locational and network efficiency indicators of spatial accessibility were calculated using network analysis in GIS. The results showed that the improvements differ according to the accessibility indicator employed; however, they generally showed benefits in consolidated urban centers and corridors near investment and industrial areas. In contrast, more distant and rural areas presented limited and irregular benefits.
Admiramos 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 Bello
La 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.
Alma aristotélica e mente contemporânea: divergências e convergências de um problema difícil
(Editora Fi, 2022) Boeri, Marcelo D.
Analysis of Backward Euler Primal DPG Methods
(2021) Führer, Thomas; Heuer, Norbert; Karkulik, Michael
We 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.
Analyzing 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, Rodrigo
Solar 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.
Archivo Fílmico UC: Aproximaciones a la representación audiovisual universitaria 1964-1977
Foxley, Susana; Urrutia Neno, Carolina; Vergara, Ximena
Somos 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.
Are the school choices of indigenous students affected by discrimination? Evidence from Chile
(2023) Hofflinger, Álvaro; Villalobos, Cristóbal; Cárdenas, Loreto; Treviño Villarreal, Juan Ernesto
A 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.
Argumentative 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; UC
Given 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
Arica, 1950-80: la forma urbana del desarrollo. Estructura y lógica de partes en el crecimiento extensivo
(2019) Torrent, Horacio
La ponencia presenta las formas que asumió la configuración del crecimiento extensivo de una ciudad de tamaño medio, empleando los instrumentos del análisis urbano para la identificación de los proyectos –básicamente urbano residenciales- que propendieron a la configuración de una ciudad de partes. Arica, constituyó entre los años cincuenta y setenta, un laboratorio particular en el que se caracterizó esta relación entre arquitectura y ciudad de manera excepcional. Se presentan así los crecimientos de la planta urbana, y el análisis de una serie de proyectos de vivienda que propusieron el crecimiento expansivo, en directa relación con las lógicas internas a cada porción o parte y una lectura interpretativa del tejido, en correlación con los planes que trataron de controlar el desarrollo urbano.
Assessment 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, Javiera
Little 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.
Association between obesity and atopic dermatitis in children: A case-control study in a high obesity prevalence population
(2022) Iturriaga, Carolina; Bustos, María Francisca; Le Roy, Catalina; Rodríguez, Rocío; Cifuentes, Lorena; Silva-Valenzuela, Sergio; Vera-Kellet, Cristián; Cristi, Francisca; Pérez-Mateluna, Guillermo; Cabalín, Carolina; Hoyos-Bachiloglu, Rodrigo; Camargo Jr., Carlos A.; Borzutzky Schachter, Arturo
Background/Objective: Atopic dermatitis (AD) is a chronic inflammatory skin disease. Research suggests an association between obesity and AD, although evidence is lacking from Latin American populations. This study evaluated the association of obesity with AD in children from Chile, a country with high obesity prevalence. Methods: A case-control study was performed in children with active AD (cases) and healthy controls (HCs) from Santiago, Chile. Body mass index was evaluated by z-score (z-BMI), with overweight defined as z-BMI ≥+1 and <+2, and obesity as z-BMI ≥+2. Abdominal obesity was defined by a waist circumference-to-height ratio (WHR) ≥0.5. AD severity was evaluated by Scoring AD (SCORAD) index. Results: A total of 174 children with AD and 101 controls were included. AD patients had similar overweight (27% vs. 28%) and obesity (21% vs. 26%) rates as HCs (p = .65). Abdominal obesity rates were also comparable (64% vs. 62%, p = .81). In sex-specific analyses, girls with AD had higher abdominal obesity rates than HCs (71% vs. 53%, p < .05) while boys with AD had lower abdominal obesity rates than HCs (53% vs. 75%, p = .03). Among children with AD, higher z-BMI or WHR did not correlate with higher SCORAD, eosinophil counts or total IgE. Conclusion: In our study, Chilean children with AD had high but similar rates of obesity as HCs, but showed sex-specific associations of abdominal obesity and AD. Further research is needed to evaluate these associations and the roles that weight excess and weight loss could play in the pathogenesis and treatment of AD.
Biomechanical analysis of expert anesthesiologists and novice residents performing a simulated central venous access procedure
(2021) Villagrán Gutiérrez, Ignacio Andrés; Moenne Vargas, Cristóbal Matías; Aguilera Siviragol, Victoria Ignacia; Garcia, Vicente; Reyes, Jose Tomas; Rodriguez, Sebastian; Miranda Mendoza, Constanza; Altermatt, Fernando; Fuentes López, Eduardo; Delgado Bravo, Mauricio Antonio; Neyem, Andrés
Background Central venous access (CVA) is a frequent procedure taught in medical residencies. However, since CVA is a high-risk procedure requiring a detailed teaching and learning process to ensure trainee proficiency, it is necessary to determine objective differences between the expert’s and the novice’s performance to guide novice practitioners during their training process. This study compares experts’ and novices’ biomechanical variables during a simulated CVA performance. Methods Seven experts and seven novices were part of this study. The participants’ motion data during a CVA simulation procedure was collected using the Vicon Motion System. The procedure was divided into four stages for analysis, and each hand’s speed, acceleration, and jerk were obtained. Also, the procedural time was analyzed. Descriptive analysis and multilevel linear models with random intercept and interaction were used to analyze group, hand, and stage differences. Results There were statistically significant differences between experts and novices regarding time, speed, acceleration, and jerk during a simulated CVA performance. These differences vary significantly by the procedure stage for right-hand acceleration and left-hand jerk. Conclusions Experts take less time to perform the CVA procedure, which is reflected in higher speed, acceleration, and jerk values. This difference varies according to the procedure’s stage, depending on the hand and variable studied, demonstrating that these variables could play an essential role in differentiating between experts and novices, and could be used when designing training strategies.
Caracterización sobre explicaciones de docentes en servicio acerca de la noción científica de disolución
(2022) Quintanilla Gatica, Mario R.; Mercado Baeza, Marcelo Eduardo
En 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.
CHAIRS: 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.
Change in early childhood classroom interaction quality after a professional development programme
(2021) Torres Faúndez, Elisa Teresita; Narea Biscupovich, Marigen Soledad; Mendive Criado, Susana; UC
Chilean EFL student teachers and social justice: ambiguity and uncertainties in understanding their professional pedagogical responsibility
(2022) Barahona, Malba; Ibaceta Quijanes, Ximena
Professional 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.

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