Colecciones Institucionales

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    100 años del Portal Eliseo del Campo (1925-2025): hacia la puesta en valor de un patrimonio inmueble singular del Barrio Matta
    (2023) Díaz Toledo, Yanko; Gómez Villar, Joseph; Aguilera Insunza, Carolina; Prado García, Francisco Javier; Pontificia Universidad Católica de Chile. Facultad de Arquitectura, Diseño y Estudios Urbanos
    El Portal Eliseo del Campo ha sido reconocido y valorado por la comunidad asociada como un hito emblemático para la vida del Barrio Matta. Se trata de un Inmueble de Conservación Histórica (ICH) privado de uso mixto: vivienda, comercio y talleres de oficios, inserto en la Zona Típica (ZT) «Barrio Matta Sur», que ha tenido que sobrellevar las consecuencias de la falta de mejoramientos sustanciales para enfrentar la obsolescencia física y funcional, como también la presión que ha ejercido la acelerada transformación de la ciudad, impactando negativamente en su estado de conservación y en su vinculación con la vida de barrio. Esta tesis plantea un proyecto que facilita su puesta en valor, contribuyendo a evitar la pérdida de este tipo de patrimonios de barrio. Basado en un trabajo de investigación, levantamiento, reconocimiento y valorización que el autor viene llevando a cabo desde el año 2019, y como paso siguiente, en esta tesis se plantea la elaboración participativa de los criterios y lineamientos de intervención para el Portal Eliseo del Campo, orientados a futuros proyectos de intervención que permitan superar la actual desvinculación con el barrio, deterioro y alteraciones de este valioso patrimonio inmueble singular —ad portas de cumplir 100 años—.
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    3D whole-heart grey-blood late gadolinium enhancement cardiovascular magnetic resonance imaging
    (2021) Milotta, Giorgia; Munoz, Camila; Kunze, Karl P.; Neji, Radhouene; Figliozzi, Stefano; Chiribiri, Amedeo; Hajhosseiny, R.; Masci, Pier Giorgio; Prieto Vásquez, Claudia; Botnar, René Michael
    Abstract Purpose To develop a free-breathing whole-heart isotropic-resolution 3D late gadolinium enhancement (LGE) sequence with Dixon-encoding, which provides co-registered 3D grey-blood phase-sensitive inversion-recovery (PSIR) and complementary 3D fat volumes in a single scan of < 7 min. Methods A free-breathing 3D PSIR LGE sequence with dual-echo Dixon readout with a variable density Cartesian trajectory with acceleration factor of 3 is proposed. Image navigators are acquired to correct both inversion recovery (IR)-prepared and reference volumes for 2D translational respiratory motion, enabling motion compensated PSIR reconstruction with 100% respiratory scan efficiency. An intermediate PSIR reconstruction is performed between the in-phase echoes to estimate the signal polarity which is subsequently applied to the IR-prepared water volume to generate a water grey-blood PSIR image. The IR-prepared water volume is obtained using a water/fat separation algorithm from the corresponding dual-echo readout. The complementary fat-volume is obtained after water/fat separation of the reference volume. Ten patients (6 with myocardial scar) were scanned with the proposed water/fat grey-blood 3D PSIR LGE sequence at 1.5 T and compared to breath-held grey-blood 2D LGE sequence in terms of contrast ratio (CR), contrast-to-noise ratio (CNR), scar depiction, scar transmurality, scar mass and image quality. Results Comparable CRs (p = 0.98, 0.40 and 0.83) and CNRs (p = 0.29, 0.40 and 0.26) for blood-myocardium, scar-myocardium and scar-blood respectively were obtained with the proposed free-breathing 3D water/fat LGE and 2D clinical LGE scan. Excellent agreement for scar detection, scar transmurality, scar mass (bias = 0.29%) and image quality scores (from 1: non-diagnostic to 4: excellent) of 3.8 ± 0.42 and 3.6 ± 0.69 (p > 0.99) were obtained with the 2D and 3D PSIR LGE approaches with comparable total acquisition time (p = 0.29). Similar agreement in intra and inter-observer variability were obtained for the 2D and 3D acquisition respectively. Conclusion The proposed approach enabled the acquisition of free-breathing motion-compensated isotropic-resolution 3D grey-blood PSIR LGE and fat volumes. The proposed approach showed good agreement with conventional 2D LGE in terms of CR, scar depiction and scan time, while enabling free-breathing acquisition, whole-heart coverage, reformatting in arbitrary views and visualization of both water and fat information.
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    A 1D topological insulator for light
    (2020) Pérez Tobar, Daniel Esteban; Reyes Swett, Sebastián Andrés; Pontificia Universidad Católica de Chile. Instituto de Física
    A 1D photonic topological insulator is the photonic realization of a 1D topological insulator. We show how the calculation of a topological invariant, known as the Zak phase, is a useful tool to identify different topologies in one-dimensional systems. We found topological phase transitions for the 1D photonic topological insulator and its relation to the inversion symmetry of the system.
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    A case study of the development of a valid and pragmatic implementation science measure: the Barriers and Facilitators in Implementation of Task-Sharing Mental Health interventions (BeFITS-MH) measure
    (2024) Yang, Lawrence H.; Bass, Judy K.; Le, PhuongThao D.; Singh, Ritika; Gurung, Dristy; Velasco Grandón, Paola Renée; Grivel, Margaux M.; Susser, Ezra; Cleland, Charles M.; Alvarado, Rubén; Kohrt, Brandon A.; Bhana, Arvin
    Background Few implementation science (IS) measures have been evaluated for validity, reliability and utility – the latter referring to whether a measure captures meaningful aspects of implementation contexts. We present a real-world case study of rigorous measure development in IS that assesses Barriers and Facilitators in Implementation of Task-Sharing in Mental Health services (BeFITS-MH), with the objective of offering lessons-learned and a framework to enhance measurement utility. Methods We summarize conceptual and empirical work that informed the development of the BeFITS-MH measure, including a description of the Delphi process, detailed translation and local adaptation procedures, and concurrent pilot testing. As validity and reliability are key aspects of measure development, we also report on our process of assessing the measure’s construct validity and utility for the implementation outcomes of acceptability, appropriateness, and feasibility. Results Continuous stakeholder involvement and concurrent pilot testing resulted in several adaptations of the BeFITS-MH measure’s structure, scaling, and format to enhance contextual relevance and utility. Adaptations of broad terms such as “program,” “provider type,” and “type of service” were necessary due to the heterogeneous nature of interventions, type of task-sharing providers employed, and clients served across the three global sites. Item selection benefited from the iterative process, enabling identification of relevance of key aspects of identified barriers and facilitators, and what aspects were common across sites. Program implementers’ conceptions of utility regarding the measure’s acceptability, appropriateness, and feasibility clustered across several common categories. Conclusions This case study provides a rigorous, multi-step process for developing a pragmatic IS measure. The process and lessons learned will aid in the teaching, practice and research of IS measurement development. The importance of including experiences and knowledge from different types of stakeholders in different global settings was reinforced and resulted in a more globally useful measure while allowing for locally-relevant adaptation. To increase the relevance of the measure it is important to target actionable domains that predict markers of utility (e.g., successful uptake) per program implementers’ preferences. With this case study, we provide a detailed roadmap for others seeking to develop and validate IS measures that maximize local utility and impact.
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    A case-control study of a combination of single nucleotide polymorphisms and clinical parameters to predict clinically relevant toxicity associated with fluoropyrimidine and platinum-based chemotherapy in gastric cancer
    (2021) Cordova-Delgado, Miguel; Bravo Castillo, María Loreto; Cumsille, Elisa; Hill Machado, Charlotte Nicole; Pinto, Mauricio P.; Miquel P., Juan Francisco; Rodríguez-Fernández, María; Corvalán R., Alejandro; Garrido S., Marcelo; Owen, Gareth Ivor
    Background: Fluoropyrimidine plus platinum chemotherapy remains the standard first line treatment for gastric cancer (GC). Guidelines exist for the clinical interpretation of four DPYD genotypes related to severe fluoropyrimidine toxicity within European populations. However, the frequency of these single nucleotide polymorphisms (SNPs) in the Latin American population is low (< 0.7%). No guidelines have been development for platinum. Herein, we present association between clinical factors and common SNPs in the development of grade 3–4 toxicity. Methods: Retrospectively, 224 clinical records of GC patient were screened, of which 93 patients were incorporated into the study. Eleven SNPs with minor allelic frequency above 5% in GSTP1, ERCC2, ERCC1, TP53, UMPS, SHMT1, MTHFR, ABCC2 and DPYD were assessed. Association between patient clinical characteristics and toxicity was estimated using logistic regression models and classification algorithms. Results; Reported grade ≤ 2 and 3–4 toxicities were 64.6% (61/93) and 34.4% (32/93) respectively. Selected DPYD SNPs were associated with higher toxicity (rs1801265; OR = 4.20; 95% CI = 1.70–10.95, p = 0.002), while others displayed a trend towards lower toxicity (rs1801159; OR = 0.45; 95% CI = 0.19–1.08; p = 0.071). Combination of paired SNPs demonstrated significant associations in DPYD (rs1801265), UMPS (rs1801019), ABCC2 (rs717620) and SHMT1 (rs1979277). Using multivariate logistic regression that combined age, sex, peri-operative chemotherapy, 5-FU regimen, the binary combination of the SNPs DPYD (rs1801265) + ABCC2 (rs717620), and DPYD (rs1801159) displayed the best predictive performance. A nomogram was constructed to assess the risk of developing overall toxicity. Conclusion: Pending further validation, this model could predict chemotherapy associated toxicity and improve GC patient quality of life.
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    A chemical survey of the proto-stellar system IRAS 16253-2429
    (2023) Castillo Lara, Jaime; Guzmán Veloso, Viviana; Artur de la Villarmois, Elizabeth; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    Presentamos un estudio químico de IRAS 16253-2429 (de aquí en adelante IRAS 16253), una proto-estrella de Clase 0 y de baja masa clasificada como un very low luminosity object (VeLLO) y localizada en el complejo de formación estelar ρ Ophiucus. Las moléculas CN, c-C3H2, y H2CO son detectadas por primera vez en IRAS 16253. H2CO se muestra compacta y simétrica en la región central, que incluye el disco y el envoltorio interior. c-C3H2 y CN también se presentan en la región central, pero con una emisión asimétrica y más extendida. También presentamos observaciones previas de 13CO, C17O, C18O, SO, CO, C2H y N2H+, con detecciones tentativas de DCO+ y N2D+. C2H se presenta en las paredes de la cavidad, en ambas direcciones de la ejección de gas, pero principalmente en la dirección norte. 13CO está presente en la región central y en la cavidad sur, C18O muestra una emisión compacta y simétrica, CO traza ambas direcciones de la ejección de gas, SO y C17O están centradas pero extendidas y asimétricas, y N2H+ está presente en el envoltorio exterior. A través de un diagrama rotacional para H2CO, estimamos una temperatura rotacional de ∼ 9.3K para la molecula. Esta baja temperatura rotacional sugiere un régimen sub-termal para H2CO, lo que a su vez implica que H2CO está presente sólo en el envoltorio interno, y no en el disco. A través de un ajuste de estructura hiperfina para N2H+, se estima una temperatura de excitación de ∼ 4 K para la molécula, esta baja temperatura de excitación también sugiere un régimen sub-termal, consistente con las bajas densidades del envoltorio exterior. Comparamos nuestros resultados con otros estudios de otras fuentes de Clase 0, pero más masivas. Encontramos que, en contra de nuestras expectativas, los trazadores de gas frío DCO+, N2H+ y N2D+ no son más abundantes en este VeLLO en comparación a otras proto-estrellas más masivas. Nuestros resultados sugieren que la química de IRAS 16253 es una versión a menor escala de la química encontrada en fuentes de Clase 0 más masivas.
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    A cluster randomized trial of interferon ß-1a for the reduction of transmission of SARS-Cov-2: protocol for the Containing Coronavirus Disease 19 trial (ConCorD-19)
    (2021) Iturriaga, Carolina; Eiffler, Nat; Aniba, Rad; Pérez Mateluna, Guillermo; Meyer, Jessica K. V.; Severino Cuevas, Nicolás Felipe; Borzutzky Schachter, Arturo; Perret Pérez, Cecilia; Castro Rodríguez, José Antonio; García-Huidobro Munita, Diego Nicolás; Iturriaga, Carolina; Eiffler, Nat; Aniba, Rad; Pérez Mateluna, Guillermo; Meyer, Jessica K. V.; Severino Cuevas, Nicolás Felipe; Borzutzky Schachter, Arturo; Perret Pérez, Cecilia; Castro Rodríguez, José Antonio; García-Huidobro Munita, Diego Nicolás; Iturriaga, Carolina; Eiffler, Nat; Aniba, Rad; Pérez Mateluna, Guillermo; Meyer, Jessica K. V.; Severino Cuevas, Nicolás Felipe; Borzutzky Schachter, Arturo; Perret Pérez, Cecilia; Castro Rodríguez, José Antonio; García-Huidobro Munita, Diego Nicolás; Iturriaga, Carolina; Eiffler, Nat; Aniba, Rad; Pérez Mateluna, Guillermo; Meyer, Jessica K. V.; Severino Cuevas, Nicolás Felipe; Borzutzky Schachter, Arturo; Perret Pérez, Cecilia; Castro Rodríguez, José Antonio; García-Huidobro Munita, Diego Nicolás
    Abstract Background SARS-CoV-2 infection rapidly spreads in populations due to the high rates of community transmission. Interrupting the shedding of SARS-CoV-2 may reduce the incidence of Coronavirus Disease 19 (COVID-19). Herein we provide a protocol for a cluster randomized trial that will examine the effectiveness of treatment with interferon (IFN) ß-1a compared to standard of care in limiting the transmission of SARS-CoV-2. Co-primary objectives are to determine whether IFN therapy reduces (a) the proportion of infected cases shedding SARS-CoV-2 at day 11 post randomization and (b) the incidence of transmission of SARS-CoV-2 infection from index cases to treatment-eligible household post-exposure contacts at day 11 after randomization. Secondary objectives include assessing the impact of IFN treatment on duration of viral clearance, hospitalizations and fatalities, and evaluating the safety of IFN treatment. Methods Three hundred and ten households, each including an index case with a recent COVID-19 diagnosis and at least one asymptomatic treatment-eligible household contact, will be randomized to receive 3 doses of 125 μg IFN ß-1a by subcutaneous administration (days 1, 6, and 11), or standard of care. All participants will be followed until day 29. Discussion The results from this trial will identify whether IFN ß treatment of mild or moderate COVID-19 cases accelerates viral clearance and prevents disease progression and whether IFN ß treatment of post-exposure contacts of COVID-19 cases reduces transmission of infection. Trial Registration: This trial is registered at ClinicalTrials.gov NCT04552379; date of registration September 17, 2020.
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    A cognitive approach to the teaching of phrasal verbs to EFL adult learners in blended courses
    (2021) Flores Díaz, Paulina A.; Rundquist, Eric; Pontificia Universidad Católica de Chile. Facultad de Letras
    The present action-research case study addressed the issue of phrasal verb learning in an EFL context. It aimed to evaluate the impact of a Cognitive Linguistics (CL) teaching methodology on students' retention of novel phrasal verbs with the preposition up. It also intended to assess the suitability of using metaphorical extensions of up to understand new phrasal verbs and to examine students’ perception of a CL teaching methodology for phrasal verbs learning. To do so, an AR cycle was developed, first implementing a pre-test to collect information about the students' previous knowledge on the subject, then implementing a pedagogical intervention and finally evaluating the results of the proposed methodology. This cycle was developed twice with two different groups of EFL learners enrolled in English blended courses and two different strategies were taken: representation and identification of metaphorical extensions of the preposition up. The results of this study showed that the proposed CL methodology seemed to have a positive effect on participants’ retention of novel phrasal verbs. These results are directly related to participants’ perception of this approach, which was also positive. Moreover, findings do not suggest a direct relationship between identification or representation of metaphorical extensions of up and understanding of novel phrasal verbs.
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    A collaborative, computer-assisted, psycho-educational intervention for depressed patients with chronic disease at primary care: protocol for a cluster randomized controlled trial
    (2021) Rojas Castillo, María Graciela; Martínez, Pablo; Guajardo, Viviana; Campos Romero, Solange; Herrera Salinas, Pablo; Vöhringer, Paul; Gómez, Víctor; Szabo, Wilsa; Araya, Ricardo
    Abstract Background Depression and chronic diseases are frequently comorbid public health problems. However, clinical guidelines often fail to consider comorbidities. This study protocol describes a cluster randomized trial (CRT) aimed to compare the effectiveness of a collaborative, computer-assisted, psycho-educational intervention versus enhanced usual care (EUC) in the treatment of depressed patients with hypertension and/or diabetes in primary care clinics (PCC) in Santiago, Chile. Methods Two-arm, single-blind, CRT carried out at two municipalities in Santiago, Chile. Eight PCC will be randomly assigned (1:1 ratio within each municipality, 4 PCC in each municipality) to the INTERVENTION or EUC. A total of 360 depressed patients, aged at least 18 years, with Patient Health Questionnaire-9 Item [PHQ-9] scores ≥15, and enrolled in the Cardiovascular Health Program at the participating PCC. Patients with alcohol/substance abuse; current treatment for depression, bipolar disorder, or psychosis; illiteracy; severe impairment; and resident in long-term care facilities, will be excluded. Patients in both arms will be invited to use the Web page of the project, which includes basic health education information. Patients in the INTERVENTION will receive eight sessions of a computer-assisted, psycho-educational intervention delivered by trained therapists, a structured telephone calls to monitor progress, and usual medical care for chronic diseases. Therapists will receive biweekly and monthly supervision by psychologist and psychiatrist, respectively. A monthly meeting will be held between the PCC team and a member of the research team to ensure continuity of care. Patients in EUC will receive depression treatment according to clinical guidelines and usual medical care for chronic diseases. Outcome assessments will be conducted at 3, 6, and 12 months after enrollment. The primary outcome will be depression improvement at 6 months, defined as ≥50% reduction in baseline PHQ-9 scores. Intention-to-treat analyses will be performed. Discussion This study will be one of the first to provide evidence for the effectiveness of a collaborative, computer-assisted, psycho-educational intervention for depressed patients with chronic disease at primary care in a Latin American country. Trial registration retrospectively registered in ClinicalTrials.gov , first posted: November 3, 2020, under identifier: NCT04613076 .
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    A comprehensive overview of the genetic diversity in Thylamys elegans (Didelphimorphia : Didelphidae) : establishing the phylogeographic determinants
    (2021) Boric Bargetto, Dusan Vladimir; Zúñiga Reinoso, Álvaro; Inostroza Michel, Óscar; Rodríguez Serrano, Enrique Alfonso; González Acuña, Daniel; Palma Vásquez, Ramón Eduardo; Hernández, Cristián E.
    Background: For the genus Thylamys, the rivers have been reported as barriers to dispersal, limiting current and historical distribution of its lineages. We hypothesized that the Maipo river has affected the genetic structure of northern and southern lineages of Thylamys elegans, recovering a phylogenetic relationships with reciprocally monophyletic sister groups on opposite river banks. We evaluated the role of other rivers in the Mediterranean zone of Chile as historical and recent modulators of the biogeographic processes of this species. Methods: We applied a phylogeographic approach, using the cytochrome-b mitochondrial gene for 93 individuals of T. elegans, from 37 localities in a latitudinal gradient between 21°25’ and 35˚56’S, encompassing a geographic area between the Atacama Desert and most of the Mediterranean Chilean zone. Results: The phylogenetics results recovered six lineages within T. elegans: Thylamys elegans elegans, Thylamys elegans coquimbensis, the Loa lineage and three other lineages not described previously (Aconcagua, South 1 and South 2). We suggest that following rivers play a role like primary barrier: the Maipo river in the genetic differentiation of northern and southern ancestral lineages, and the Mataquito river and its tributary Teno river for the South 1 and South 2 lineages. On the other hand, the Quilimarí river preserve the genetic divergence in T. e. coquimbensis and Aconcagua lineage and the Aconcagua river in Aconcagua lineage and T. e. elegans acting like secondary barriers. Conclusions: We concluded that the genetic diversity and biogeographic history of T. elegans was shaped by mountain glaciers, changes in river water levels during the Pleistocene glaciations and hyperaridity, promoting the differentiation and persistance of the T. elegans lineages.
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    A critical analysis of Shuryak’s Predictive Radiocarcinogenesis Model
    (2024) Heumann Schröder, Nicolás Matthias; Sánchez Nieto, Beatriz; Espinoza Bornscheuer, Ignacio Guillermo; Pontificia Universidad Católica de Chile. Instituto de Física
    Objective: To critically analyze, simplify and implement a predictive radiocarcinogenesis model to estimate the risk of secondary cancer after RT which can effectively compare different radiotherapy treatment plans with the aim of having an additional element of information during the decision-making process for the best RT plan.Methodology: A Python software was developed that was able to implement the model proposed by Shuryak et al. (2009). Simplifications and minor corrections were made which allowed for more compactness and more efficient run times. The model was then reparametrized with newer data from the Surveillance, Epidemiology, and End Results Program (SEER) database and several epidemiological studies using Bayesian Inference. Uncertainty propagation studies were then conducted to understand their propagation better. Finally, the model with its new parameters was applied to a selection of prostate plans to determine if it could construct a risk hierarchy.Results: The model was successfully reparametrized with newer data. Although some parameters show significant deviation from Shuryak’s original parameters, they are mostly on the same order of magnitude, and the differences arise likely due to differences in fitted data and the fitting process itself. Shuryak’s model successfully built a risk hierarchy between prostate plans, although it deviated from the more simplistic linear non-threshold BEIR VII model. It was also possible to simplify some complex mathematical equations, both in general and for particular cases, allowing for easier implementation and more efficient run times.Conclusions: Shuryak’s model was successfully reparametrized and implemented, showing potential to become clinically applicable. However, more comparisons between the model’s result and epidemiological data must be made to evaluate its accuracy better, and more concise and complete second primary cancer studies must be used before the model is reliable enough for clinical decision-making.
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    A differentiable adaptive computation time algorithm for neural networks
    (2021) Eyzaguirre, Cristóbal; Soto Arriaza, Álvaro Marcelo; Pontificia Universidad Católica de Chile. Escuela de Ingeniería
    A pesar de las mejoras sustanciales en los resultados que aportan los modelos de redes neuronales, su aplicación generalizada se ha visto limitada por su elevado coste computacional debido a redundancias presentes en este tipo de arquitecturas. M´as a´un, esta tesis postula que dichas ineficiencias no pueden resolverse completamente con métodos estáticos, debido a que algunas redundancias son intrínsecas al problema que se resuelve y, por lo tanto, son dependientes de los datos. Aunque en respuesta a este problema se han propuesto arquitecturas dinámicas que se adaptan a la entrada, todas ellas comparten la limitación de que no son totalmente diferenciables. Ante esta limitación común, nuestro trabajo propone la primera implementación de un algoritmo de tiempo de cómputo dinámico que es totalmente diferenciable: un algoritmo dinámico diferenciable de early exiting que llamamos DACT. Validamos las ventajas de nuestro enfoque, tanto en términos de resultados como de interpretabilidad, utilizando dos de los casos de uso más comunes, y descubrimos que el DACT puede conllevar: i) importantes ganancias de rendimiento cuando sustituye a los enfoques dinámicos existentes, o ii) eliminar las redundancias intrínsecas cuando se utiliza para complementar modelos estáticos. De hecho, en el dominio del procesamiento de lenguaje descubrimos que nuestro enfoque es mejor para reducir el número de bloques Transformer utilizados por los modelos BERT sin pérdida de desempeño en una serie de tareas. Del mismo modo, mostramos una reducción significativa en el número de pasos recurrentes necesarios cuando se aplica a la arquitectura MAC, superando los resultados tanto de los algoritmos adaptativos existentes como de aquellos estáticos comparables, a la vez que se mejora la transparencia del modelo. Además, nuestro modelo muestra una notable estabilidad, respondiendo de forma predecible a los cambios de los hiperparámetros, a la vez que equilibra la precisión y la complejidad de forma razonable.
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    A Escala Humana. Reconfigurando la calle para una vida urbana vibrante, el caso de la Alameda en Estación Central
    (2024) Ebensperger Escalona, Ignacio Andrés; Hurtubia González, Ricardo; Echiburú Altamirano, Tomás; Pontificia Universidad Católica de Chile. Facultad de Arquitectura, Diseño y Estudios Urbanos
    Desde la segunda mitad del siglo XX, varias ciudades han privilegiado un desarrollo que se centra en la distribución del espacio en las calles para acomodar el correcto funcionamiento de los medios de transporte motorizados, relegando la escala humana de éstas.Para esta tesis se investigó sobre qué es la escala humana dentro del ámbito de la arquitectura y urbanismo y el cómo esta se aplica al diseño de espacios públicos (E. P.). Junto a comprender, en qué medida los medios de transporte sostenible pueden jugar un rol en la construcción de un E. P. en la calle, que fomente una vida urbana vibrante. Comprendidos estos antecedentes, se realizó una investigación cuantitativa en el sector de la Alameda en la comuna de Estación Central. Registrando la distribución espacial del perfil de la calle y el flujo promedio de usuarios en horarios específicos. Para luego levantar mediante una investigación cualitativa el cómo se percibe y experimenta la estadía en la acera.La investigación demuestra lo concreto de las posibles operaciones para poder revertir la situación actual de las calles y lograr una escala humana en estas. Asimismo, se demuestra el potencial que tienen los medios de transporte sostenible para iniciar este tipo de cambios tanto en el espacio físico como en la percepción de la ciudad y la cultura que se tiene en torno al cómo una persona se mueve dentro de esta. Por otro lado, los resultados de los levantamientos muestran una situación en el sector de estudio que acoge fuertemente la predominancia y favorecimiento hacia los medios de transporte motorizados, además de una percepción negativa por parte de los usuarios de las condiciones en que se encuentra la acera y la experiencia de la estadía en ella.Concluyendo sobre la importancia que tiene para la vida cotidiana de las personas y su experiencia en la ciudad el recuperar la escala humana en las calles de ésta. También se resalta el rol como motor de cambio que pueden llegar a tener los medios de transporte sostenible y la infraestructura asociada para llevar a cabo esta nueva visión de ciudad. Por último se propone un proyecto de rediseño de una intersección y segmento de la Alameda en el sector de estudio, para ilustrar posibles soluciones.
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    A framework to analyze institutional systems for managing and governing water resources
    (2023) Blanco, Elisa; Donoso H., Guillermo; Pontificia Universidad Católica de Chile. Facultad de Agronomía y Sistemas Naturales
    Garantizar el acceso al agua implica más que una cuestión de disponibilidad, sino también una cuestión de gestión y gobernanza. Si bien algunos sistemas hídricos han demostrado éxito en la gestión eficiente de sus escasos recursos, muchos enfrentan desafíos cuando se trata de organizar y coordinar la asignación y gestión sostenible de sus recursos. Para comprender los sistemas de recursos naturales, se han desarrollado los Principios de Diseño de Bienes Comunes, los Sistemas Socio-ecológicos (SES, por sus siglas en inglés) y el marco de Análisis y Desarrollo Institucional (Institutional Analysis and Development framework, IAD), todos ellos arraigados en teorías de acción colectiva. Estas teorías se han empleado para comprender las formas en que operan los sistemas institucionales complejos y los, a menudo, intrincados procesos de toma de decisiones que tienen lugar dentro de ellos. Al mismo tiempo, para establecer reglas y comprender los roles dentro de estos sistemas institucionales, se ha desarrollado la teoría del diseño de mecanismos. Estas teorías aún no se han adaptado completamente para incorporar las complejidades y la fragmentación inherentes a los marcos institucionales del agua. Por lo tanto, la presente tesis pretende contribuir al avance del conocimiento y la comprensión sobre la gestión de los sistemas socio-ecológicos hídricos. Aspira a comprender, desentrañar, analizar y aplicar estas teorías, hacia el análisis de los sistemas hídricos. Con ello, el objetivo es desarrollar un marco analítico que pueda estudiar y comprender mejor los sistemas socio-ecológicos del agua para mejorar sus instituciones y gobernanza. Al hacerlo, este trabajo busca ofrecer orientación a una audiencia amplia, incluidos usuarios del agua, investigadores, formuladores de políticas y autoridades responsables de diseñar políticas y proteger la sostenibilidad de los recursos hídricos.
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    A genre-based approach to teaching personal recount writing to 6th grade EFL students in Chile
    (2023) Ortega, Abigail; Gajardo Moller, Consuelo; Pontificia Universidad Católica de Chile. Facultad de Letras
    This mixed-methods study intended to implement a genre-based approach to writing, informed by SFL (Systemic Functional Linguistics), in a Chilean EFL (English as a Foreign Language) context. The primary aim of this research was to evaluate the effectiveness and student perceptions of a genre-based pedagogical intervention (GBP) designed to enhance the writing proficiency of sixth-grade EFL students in producing personal recount texts.The writing assignments of five students were analyzed, engaging in the production of a specific form of personal recount text: diary entries. The assessment of the effectiveness of the genre-based intervention involved the analysis of pre-test and post-test diary entries, with a focus on the social purpose and language choices inherent to the personal recount genre. Data was collected through quantitative analysis of diary entries, and qualitative analysis of the participants’ responses to an open-ended questionnaire.The findings of the pre-test and post-test compositions, supported by a statistical analysis, identified a substantial improvement in students' overall personal recount writing skills following the implementation of the genre-based approach, in aspects such as use of evaluative language and cohesively connecting a sequence of main events. Results also indicated that students' perspectives were mostly positively impacted by the GBP's application, with students indicating that each stage of the method was effective in helping them write their compositions. Overall, the results highlight students' predominantly positive perspectives on the application of the GBP, emphasizing the effectiveness of each stage of the method in facilitating their composition process in aspects such as genre comprehension and easiness in the writing process. Ultimately, this research contributes to the understanding of the potential of genre-based pedagogy in the Chilean EFL context and its impact on students' writing performance and perceptions.
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    A Health Technician-delivered Brief Intervention linked to AUDIT for reduction of alcohol use in Chilean primary care: a randomized controlled trial
    (2021) Barticevic Lantadilla, Nicolás A.; Poblete A., Fernando; Zuzulich Pavez, María Soledad; Rodríguez Lobo, María Victoria; Quevedo, Diego; Sena, Brena F.; Bradshaw, Laura
    Abstract Background Because of the shortage of health professionals in Chilean primary care, Health Technicians (HT) are providing Brief Interventions (BI) for risky alcohol consumption. We compared the efficacy of two AUDIT-linked interventions provided by HTs: an informative leaflet and a BI plus leaflet. Methods This is a parallel-group randomized controlled trial with 1:1 randomization. Participants were identified through screening with the Alcohol Use Disorders Identification Test (AUDIT) at five primary care centers between March 2016 and July 2017. People older than 18 years at intermediate-risk (AUDIT score 8 to 15, inclusive) were randomized to receive either an HT-delivered BI (n = 174) or an informative leaflet (n = 168). Only data from participants (n = 294) who completed the 6-month assessment were analyzed. The leaflet was delivered without further advice. It contains alcohol consumption limits, a change planner, and strategies to decrease drinking. The BI was a 5-min discussion on the leaflet´s content plus normative feedback, tailored information on alcohol and health, and a change plan. The change in the AUDIT risk category six months after randomization (primary outcome) was compared among groups with a Chi-squared test. Changes in the secondary outcomes, which were scores on the AUDIT and the AUDIT´s consumption items (AUDIT-C), were compared with T-tests. Mixed-effects linear models adjusted for potential confounders. Outcome adjudicators were blinded to group assignment. Results At 6-month follow-up, low-risk alcohol consumption was observed in 119 (80%) participants in the BI group, and in 103 (71%) in the leaflet group, with no difference among groups ( $$\chi 2$$ χ 2 [1, N = 294] = 2.6, p = 0.1; adjusted odds ratio 0.6; 95% confidence interval [CI] 0.34, 1.05). The mean AUDIT score decreased by 5.76 points in the BI group, and by 5.07 in the leaflet group, which represents a 0.86 AUDIT point reduction attributable to the BI (secondary outcome) (T = 2.03, p = 0.043; adjusted mean difference 0.86 CI 0.06, 1.66). Conclusions The AUDIT-linked BI delivered by HTs was not associated with a greater reduction of risky alcohol consumption than an informative leaflet. Delivering a leaflet could be more efficient than a BI when provided by HTs; however, more research on the effectiveness of the leaflet is needed. Trial registration ClinicalTrials.gov NCT02642757 (December 30, 2015) https://clinicaltrials.gov/ct2/show/NCT02642757 .
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    A low-complexity channel training method for efficient SVD beamforming over MIMO channels
    (2021) Kettlun, Felipe; Rosas de Andraca, Fernando Ernesto; Oberli Graf, Christian Robert
    Abstract Singular value decomposition (SVD) beamforming is an attractive tool for reducing the energy consumption of data transmissions in wireless sensor networks whose nodes are equipped with multiple antennas. However, this method is often not practical due to two important shortcomings: it requires channel state information at the transmitter and the computation of the SVD of the channel matrix is generally too complex. To deal with these issues, we propose a method for establishing an SVD beamforming link without requiring feedback of actual channel or SVD coefficients to the transmitter. Concretely, our method takes advantage of channel reciprocity and a power iteration algorithm (PIA) for determining the precoding and decoding singular vectors from received preamble sequences. A low-complexity version that performs no iterations is proposed and shown to have a signal-to-noise-ratio (SNR) loss within 1 dB of the bit error rate of SVD beamforming with least squares channel estimates. The low-complexity method significantly outperforms maximum ratio combining diversity and Alamouti coding. We also show that the computational cost of the proposed PIA-based method is less than the one of using the Golub–Reinsch algorithm for obtaining the SVD. The number of computations of the low-complexity version is an order of magnitude smaller than with Golub–Reinsch. This difference grows further with antenna array size.
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    A new approach for the acquisition of trauma surgical skills: an OSCE type of simulation training program
    (2022) Ortiz Koh, Catalina Alejandra; Contreras Bertolo, Caterina; Vela Ulloa, Javier Ignacio; Belmar, Francisca; Paul, Ivan; Achurra Tirado, Pablo; Varas Cohen, Julián
    Background Worldwide, trauma-related deaths are one of the main causes of mortality. Appropriate surgical treatment is crucial to prevent mortality, however, in the past decade, general surgery residents’ exposure to trauma cases has decreased, particularly since the COVID-19 pandemic. In this context, accessible simulation-based training scenarios are essential. Methods A low-cost, previously tested OSCE scenario for the evaluation of surgical skills in trauma was implemented as part of a short training boot camp for residents and recently graduated surgeons. The following stations were included bowel anastomosis, vascular anastomosis, penetrating lung injury, penetrating cardiac injury, and gastric perforation (laparoscopic suturing). A total of 75 participants from 15 diferent programs were recruited. Each station was videotaped in high defni tion and assessed in a remote and asynchronous manner. The level of competency was assessed through global and specifc rating scales alongside procedural times. Self-confdence to perform the procedure as the leading surgeon was evaluated before and after training. Results Statistically signifcant diferences were found in pre-training scores between groups for all stations. The lowest scores were obtained in the cardiac and lung injury stations. After training, participants signifcantly increased their level of competence in both grading systems. Procedural times for the pulmonary tractotomy, bowel anastomosis, and vascular anastomosis stations increased after training. A signifcant improvement in self-confdence was shown in all stations. Conclusion An OSCE scenario for training surgical skills in trauma was efective in improving profciency level and self confdence. Low pre-training scores and level of confdence in the cardiac and lung injury stations represent a defcit in resi dency programs that should be addressed. The incorporation of simulation-based teaching tools at early stages in residency would be benefcial when future surgeons face extremely severe trauma scenarios. Keywords Trauma surgery · Simulation training · Surgical training · Surgical education tec
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    A Predictive Simulation Chain for DNA Damage and Cell Death Induced By Ionizing Radiation
    (2023) Salgado Maldonado, Sebastián Ignacio; Russomando, Andrea; Pontificia Universidad Católica de Chile. Facultad de Física
    Proton therapy is an effective form of cancer treatment that uses proton beams in the MeV range to destroy cancer cells. However, the protons' efficiency at killing cells varies as the beam penetrates tissue, thus, their biologically effective range presents a significant challenge in predicting the effects of proton irradiation. In this work, the development of a novel methodology in the determination the biological effect of protons through Monte Carlo (MC) beam transport and DNA damage simulations in combination with mechanistic cellular survival modeling is presented. The simulations show that the DNA damage generation and subsequent cell killing is affected by the evolution of the proton beam as it penetrates tissue without recurring to a definition of relative biological effectiveness (RBE). This also shows that a fixed RBE of 1.1 such as the one used in the clinics today may not be enough to predict the biological effect. Furthermore, the proton killing probability shift with respect to their deposited dose, i.e., the biological penumbrae, is estimated employing this framework. The methodology is also tested in various conditions, i.e., different mechanistic model parametrizations, considering proton beam fragmentation, and accounting for changes related to the cell cycle. Results suggest that this framework can provide insight into the biological effects of proton therapy and improve the accuracy of treatment planning. This study contributes to the field of radiobiology by providing a method to reliably simulate the biological response of living tissues to proton radiation, making us able to potentially answer important questions such as the proton biological range uncertainty, the effects of cell phase upon its survival probability, the contribution of heavier ion fragmentation to the DNA damage, among many others presented in this thesis.