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Dynamic modelling and thermal control of an integrated membrane distillation/heat pump process for hypersaline brines treatment
No full textTesis (Magíster en Ciencias de la Ingeniería)--Pontificia Universidad Católica de Chile, 2025Control over membrane distillation-crystallization (MDCr) systems has gained considerable interest due to the benefits this technology offers in terms of water recovery and the concentration of hypersaline brines. This work presents the dynamic modeling and thermal control of a membrane distillation system integrated with a heat pump for energy recovery, designed for the treatment of hypersaline briners. The proposed fist-principles model, developed in MATLAB/Simulink represents an early-stage digital twin of a pilot-scale membrane distillation plant, incorporating mass and heat transfer phenomena across the membrane module and associated equipment. This system is currently under construction at the Advanced Mining Technology Center (AMTC), supporting the model’s relevance to real-world implementation and design workflows. Two control strategies were assessed to regulate the membrane and permeate temperatures: (i) a PID controller tuned using classical methods (Ziegler–Nichols and IMC-PI), and (ii) a Reinforcement Learning (RL) -based controller using a Deep Deterministic Policy Gradient (DDPG) agent. Both strategies were tested under realistic disturbances and structural variations in the membrane module to evaluate their robustness and adaptability. The PID control strategy resulted in energy savings of up to 45%,without significant losses in water recovery. The RL agent, trained for approximately two hours, achieved acceptable control performance, though it was outperformed by the PID strategy under the conditions tested. Results showed that the PID method outperformed the implemented RL agent by 88%. The results indicate that the PID control strategy outperformed in its ability to regulate the temperature of both tanks, while the RL controller showed potential to be used in this context. However, its performance was limited by the available computational. esources during training. This study contributes to advancing the technological maturity of membrane distillation systems by demonstrating model-based control design workflows aimed at improving scalability and energy efficiency
El estado es un macho violador: reconsidering the state as a site for peacebuilding
No full textIn most peacebuilding processes, the state is seen, particularly by the international community, as a primary and central arbitrator in peacebuilding and transitional justice processes. In this article, I critique the global system’s centralisation of the state, using Colombia as a case study. This critique of the state as a central site for peacebuilding in Colombia is driven from three key bodies of work: legal feminist institutional reform, radical Latin American feminist perspectives on the state as un macho violador, and Afro-Colombian intellectual traditions which call for ethnic regional autonomy, particularly from the Pacific region of the country. I engage with this work through my own ethnographic methodology conducted in both the capital of the country, Bogotá, and the Pacific region, primarily the port city of Buenaventura in Valle del Cauca. This critical gaze of the undefinable state thus brings into question if the state can ever use force or violence in a legitimate fashion, and offers alternative approaches from Black and feminist intellectual traditions. This article contributes to debates on peacebuilding and transitional justice by challenging the state’s presumed legitimacy in those processes in the case of Colombia
El reverso de la máscara y el vacío: una lectura crítica y proyectual desde el caso Miraflores 649, Santiago
No full textTesis (Arquitecto y Magíster en Patrimonio Cultural)--Pontificia Universidad Católica de Chile, 2025Esta investigación aborda el fenómeno del vaciamiento interior de edificios patrimoniales en la comuna de Santiago, una práctica que tiende a conservar únicamente la fachada como representación del valor histórico, despojando al interior de su dimensión material y simbólica. A partir de un catastro de casos y un análisis normativo, se expone cómo esta lógica ha favorecido intervenciones que priorizan la imagen urbana por sobre la memoria arquitectónica integral. Frente a este escenario, se propone una mirada alternativa centrada en los elementos remanentes, en particular los muros medianeros y el vacío resultante, como portadores de memoria patrimonial.El edificio ubicado en Miraflores 649 elegido caso de estudio permite explorar críticamente el valor de lo que permanece tras el vaciamiento. A través del estudio urbano, histórico y arquitectónico del inmueble, se reconoce en el vacío una oportunidad para proyectar sin ocultar el daño ni reconstruir lo perdido, proponiendo una intervención que dialogue con las huellas existentes. Así, esta investigación plantea una forma de actuar en el patrimonio desde la honestidad material y la memoria del vacío
The Way to Someone’s Mind Is through Their Stomach: Vegans and Culinary Activism
No full textThis article aims to understand how vegans promote a society without animal exploitation through food. Based on material from three years of fieldwork with young vegans in Santiago, Chile, this research shows that vegans utilize commensality and social media to present food as a joyful and friendly way to convince others about the viability of following a plant-based diet, avoiding conflict and evading talking about animals’ exploitation. The interviewees mentioned that sharing their dishes with non-vegans is a form of activism. This involves presenting new flavours and preparations and disseminating know-how about vegan cuisine, including information about ingredients and recipes. The sociological literature on lifestyle movements emphasizes that their followers employ consumption to promote changes. This research goes beyond because it argues that food is a pragmatic mechanism for socializing others into performing a political idea in everyday life
Patrimonio y memoria: un proyecto educativo sobre derechos humanos, en el Internado Nacional Barros Arana (1973 – 2024)
No full textTesis (Magíster en Patrimonio Cultural)--Pontificia Universidad Católica de Chile, 2024El Internado Nacional Barros Arana (INBA) ha destacado a lo largo de su historia por su enfoque educativo innovador, su infraestructura de calidad y su compromiso con diversas iniciativas a nivel nacional. Estos pilares han contribuido a forjar una sólida identidad institucional, caracterizada por una comunidad escolar cohesionada, aunque con matices y disonancias propias de cualquier grupo diverso.Sin embargo, la historia del INBA también está marcada por un capítulo oscuro: su uso como centro de detención y tortura durante la dictadura militar en 1973. Este evento ha dejado una profunda huella en la comunidad, y su narrativa ha sido transmitida principalmente a través de relatos orales, dando lugar a diferentes interpretaciones y, en ocasiones, dejando de lado las experiencias reales de las víctimas y el papel de la institución en aquellos años. Reconocer y visibilizar los hechos ocurridos en el INBA durante la dictadura es crucial para la justicia, la reparación del daño a las víctimas, la preservación de la memoria histórica y la sensibilización de la comunidad escolar sobre los derechos humanos. En el marco de la justicia transicional, es fundamental incluir estos espacios en los procesos de democratización y reparación, considerando los lugares de detención y tortura como parte del patrimonio cultural
El difuso límite entre respuesta y recuperación postdesastre: discusión y propuestas a partir del incendio de Quilpué (2024)
No full textEste artículo tiene como finalidad exponer las dificultades del tránsito entre un proceso de respuesta y otro de recuperación, considerando las dimensiones territoriales, culturales e institucionales involucradas en undesastre socionatural, esto con el objeto de mejorar la acción de las distintas esferas del Estado implicadas en el proceso. En función de esto, nos enfocaremos en las prácticas y experiencias de los afectados, los voluntarios y los funcionarios municipales, considerando especialmente sus experiencias en torno al proceso de respuesta y recuperación tras el incendio. Dichas experiencias se analizaron siguiendo el marco normativo vigente de la Gestión del Riesgo de Desastres (GRD), para revelar así las problemáticas principales
Cost-effectiveness of dabigatran for thromboembolic events prevention in atrial fibrillation patients in Chile
No full textBackground Atrial fibrillation (AF) is the most common sustained arrhythmia in adults, associated with significant morbidity, mortality, and economic burden due to thromboembolic events. In Chile, acenocoumarol is the most widely used anticoagulant, while access to direct oral anticoagulants (DOACs) such as dabigatran, rivaroxaban, and apixaban remains limited for AF patients. Among DOACs, dabigatran is the only one with an approved specific reversal agent (idarucizumab) available in the Chilean public system. Evaluating the cost-effectiveness of these alternatives is critical for informing resource allocation. Aims To evaluate the cost-effectiveness of dabigatran compared to acenocoumarol, rivaroxaban and apixaban, for thromboembolic events prevention in atrial fibrillation (AF) patients, from the Chilean public health payer perspective. Methods A Markov cohort model was used to represent the natural history of AF in terms of ischemic and hemorrhagic complications. Direct costs were obtained from local official sources and converted to US dollars (1 USD = 710.9 CLP at 2022). Data about major events and utilities were obtained from the literature. We applied an undifferentiated discount rate of 3% for costs and outcomes over a lifetime time horizon. Uncertainty was characterized through deterministic and probabilistic sensitivity analysis. We also examined the use of idarucizumab and prothrombin-complexes-concentrate (PCC) as reversal agents in an emergency setting as an additional scenario-analysis. Results Dabigatran was the most (cost-)effective among all alternatives (8.53 QALYs). Considering the Chilean cost-effectiveness threshold of USD 17,200 (1 GDP per capita), dabigatran was cost-effective (USD 11,042 per QALY gained), while both rivaroxaban and apixaban were dominated by dabigatran. Regarding the second-order uncertainty, at the suggested threshold, dabigatran exhibit the highest probability of being cost-effective (approximately 60%). In the reversal agent scenario, dabigatran plus idarucizumab was also found to be cost-effective in the Chilean context. Conclusion Dabigatran is cost-effective and dominates both rivaroxaban and apixaban at current publicly available prices in Chile. In addition, we expect dabigatran-idarucizumab is also expected to be cost-effective for Chilean health system when is compared against acenocoumarol-PCC as reversal agents
Crafting Policies Together: Citizen Preferences After Crisis
No full textDo citizens prefer national policies that are designed collaboratively over those produced by national government alone? The question is relevant, especially in Latin America, where citizens are sceptical of government’s capacity to address complex problems. In this article, we hypothesize that collaboratively crafted policies will be preferred over those produced by government alone in Argentina and Chile. We design conjoint experiments that ask respondents to choose among three pairs of policies, each of which varies randomly in terms of whether and with whom the government collaborates. We find that citizens in both countries tend to prefer collaboratively produced policies. This is especially the casewhen citizens have higher levels of trust in the actors with whom the national government collaborates. One important insight of our study is that, despite the costs of collaborative approaches to policymaking, citizen preferences for it could incentivize national governments to invest more resources in collaborative governance
Short/long term assessment of precast concrete block waste as a supplementary cementitious material: mechanical performance, hydration, and microstructure evolution
No full textThe massive production of cement and concrete is projected to grow significantly, with cement alone accounting for 7 %–8 % of global CO2 emissions. Reducing the environmental impact of the cement industry is critical, and low-carbon cement blends incorporating supplementary cementitious materials (SCMs) valorized from industrial wastes are a promising near-term solution. Precast concrete block waste (PCBW), an industrial waste from precast concrete plants and masonry demolition, offers potential as an SCM. This study evaluates the effects of PCBW replacement (0 %, 10 %, 20 %, and 50 % by volume) in cement paste mixtures (CPMs) on hydration and mechanical performance over short (3 days) and long (90 days) terms. The evaluation included isothermal calorimetry, compressive strength, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential thermogravimetric (DTG) analysis, and field-emission scanning electron microscopy. Predictive models using polynomial regression and support vector regression (SVR) were developed to estimate CPM compressive strength based on PCBW replacement levels and curing ages. Results showed that a 10 % PCBW replacement did not statistically affect CPM compressive strength, while 20 % replacement reduced it by 12 % at 90 days. XRD and FTIR analyses revealed high quartz and calcite content in PCBW, consistent with its chemical composition. DTG confirmed the low pozzolanic activity of PCBW compared to other SCMs. The predictive models demonstrated accuracy through 5-fold cross-validation. Using PCBW as an SCM up to 10 % is recommended to reduce environmental impacts without compromising mechanical performance
Cocaine polydrug use and its impact on intentional harm recognition: a high-density EEG study
No full textBackground Cocaine and stimulant consumption constitute a significant global issue and are associated with impaired social skills. However, the relationship between substance abuse and intentional harm recognition remains unclear. Intentional harm recognition is a crucial social cognitive ability that allows individuals to determine whether a harmful action performed by another person is deliberate or accidental. Methods The present study examined self-reported, behavioural, and neural responses associated with intentional harm recognition in n = 19 cocaine polydrug users (COC) and n = 19 healthy controls (HC). High-density electroencephalography (hdEEG) was used to measure brain activity during an Intentional Inference Task (IIT), which assesses fast intention recognition in scenarios involving deliberate or unintentional harm to people and objects. This study took place between 2014 and 2015 in Santiago, Chile. Results Behaviorally, COC exhibited slower reaction times (RT) than HC. Event-related potential (ERP) analysis revealed late frontal differences in HC when attributing intentional harm, while these differences were absent in COC. Conclusions These findings suggest a potential shift in COC towards emotional over-involvement and away from rational cognitive assessment of social information. The present results provide new insights into the recognition of intentional harm processing in cocaine polydrug users and highlight the potential clinical benefits of interventions focused on socio-emotional regulation training