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12,000 years away from the sea: Long-term circulation of Pacific shells in the Semiarid North of Chile (South America)
No full textMarine resources provide a baseline for understanding the sociohistorical trajectories of Andean societies using Pacific coastal environments. This study examines seashell distributions in northern Chile's semiarid region, revealing inland circulation patterns established over twelve thousand years. This included an extensive review of published information and new data assessed through GIS and least-cost paths. Sorting 950 specimens from 32 sites into 32 taxa, we identified consistent mobility patterns across time periods. In addition to the primary west-east trajectory from the sea to the interior, a secondary north-south inland vector was in use since the early Holocene. This study also revealed intensified shell transport during the middle Holocene, and a shift toward down-the-line exchange with reduced shell frequency at interior sites by the late Holocene, particularly in the Limarí Valley. Additionally, shell artifacts - ornaments and tools - were found more consistently in interior contexts. Together, these findings shed light on long-term human adaptation strategies in semiarid mountainous environments.ANIDChilean National Agency of Research and DevelopmentFONDECYTANID FONDECY
Quantifying Travel Time Impacts of Rainfall-Induced Cut-Slope Failures on Road Networks
No full textRainfall-induced cut-slope failures are one of the main causes of traffic disruptions in road networks, consuming 30–50% of annual road maintenance budgets. Therefore, it is crucial to analyze how traffic disruptions, resulting from cut-slope failures, impact the overall operation of road networks. In addition, as climate change alters the precipitation patterns, the frequency of these phenomena is expected to increase. For these reasons, it is essential to develop a methodology, from a risk perspective, to understand and assess how cut-slope failures impact the normal operation of road networks. This article introduces a methodology to assess the risk of traffic disruption caused by rainfall-induced cutslope failure, in terms of Origin–Destination travel time increases. The methodology comprises three stages: (1) modeling the rainfall hazard, (2) estimating the road network’s vulnerability to slope instability, and (3) quantifying risk through resulting travel time increases. A case study was performed on a road network highly vulnerable to cut-slope failure in the Biobío Region of southern Chile. The analysis using the GIS-based software revealed that rainfalls lasting more than 12 h increase average travel times by 20%, with maximum increases of about 40% for 24 h rainfalls, affecting travel between the main cities in the Biobio region and the Concepción metropolitan area. These results may be criticalfor decision-makers to identify highly exposed and vulnerable road sections in order to recommend effective mitigation strategies to reduce the risk of cut slope failures
Bridging Science and Politics: An Interdisciplinary Framework for Analysing Uncertainty in Public Policy Decision-Making
No full textTesis (Doctor of Psychology)--Pontificia Universidad Católica de Chile, 2025The doctoral thesis “Bridging Science and Politics: An Interdisciplinary Framework for Analysing Uncertainty in Public Policy Decision-Making” examines how scientific evidence is mobilised in policymaking under conditions of uncertainty. It argues that research on the science-policy interface remains fragmented because uncertainty is unevenly defined and operationalised across disciplines. The study’s overarching goal is to integrate political, methodological, and psychological dimensions of uncertainty to explain how evidence functions within decision-making processes. Grounded in a pragmatic paradigm and employing a sequential mixed-method design, the research combines conceptual, qualitative, and quantitative approaches. The empirical focus is Chile’s Law No. 20.903 on Teacher Professional Development. Three analytical strategies structure the work: (1) the Interdisciplinary Uncertainty Framework (IUF), developed through integrative review; (2) a qualitative case study using discourse and thematic analysis that integrates the Advocacy Coalition Framework (ACF) and the Social Identities in the Policy Process (SIPP) model; and (3) a mixed-method design combining qualitative coding with quantitative analyses such as Social Network Analysis, Advocacy Coalition Index, and moderation models. Findings show that evidence operates as a socially and symbolically mediated resource. The thesis demonstrates how interdisciplinary integration enables a multi-level analysis linking cognitive, structural, and behavioural dimensions of policymaking
Flexibilidad vertical en edificios de madera en altura: Estrategia habitacional sobre la estación Cerrillos del Metro de Santiago
No full textTesis (Arquitecto y Magíster en Arquitectura Sustentable y Energía)--Pontificia Universidad Católica de Chile, 2025La investigación desarrolla un sistema constructivo híbrido en madera para edificaciones en altura sobre la estación Cerrillos. A través del análisis de casos, modelaciones estructurales en SAP2000 y diseño experimental, se propone una estrategia de flexibilidad vertical que, mediante losas de CLT y pilares de Glulam, optimiza la eficiencia volumétrica al transitar del uso de m² a m³, generando espacios habitacionales adaptables, sostenibles y replicables en contextos urbanos de alta densificación
Multivariate regression models with measurement errors under generalized hyperbolic distributions
No full textTesis (Doctor en Estadísticas)--Pontificia Universidad Católica de Chile, 2025Measurement error models (MEMs), also known as errors-in-variables models, are useful tools used to describe various phenomena across multiple disciplines. MEMs establish functional relationships among variables that are observed with random measurement errors. This thesis focuses on studying the multivariate linear regression model when covariates are measured with error (MRMMEs),extending the classical multivariate linear regression framework. It is important to note that calibration models (CCMs) are a sub-class of MRMMEs. Then, we also study an extension of CCMs.Although the normality assumption is useful in some cases, the multivariate normal distribution is not appropriate when the data comes from asymmetric or heavy-tailed distributions. In practice, multivariate data are often complex in the sense that they present high levels of asymmetry, kurtosis, and outliers. For these reasons, the study of probabilistic models and inferential aspects for continuous multivariate observations is of interest. Then, this thesis aims to carry out a statistical analysis of the multivariate regression model with measurement error by considering the multivariate normal and distributions belonging to the multivariate generalized hyperbolic (GH) family.One of the significant challenges we face was dealing with identifiability issues, particulary within the multivariate GH family of distributions. To address this, we focused on the symmetric case, which includes the symmetric normal inverse Gaussian (sym NIG) distribution and the symmetric hyperbolic (sym HYP) distribution. We used the Maximum Likelihood (ML) framework for estimation through the Expectation Maximization algorithm, hypothesis testing, model assessment, and influence diagnostics in both the multivariate regression model with measurement error under the normality assumption (N-MRMME) and the multivariate regression model with measurement error under multivariate symmetric generalized hyperbolic distributions (sym GH-MRMME). In both cases, we faced the challenge of complex expressions. However the suitable properties of the multivariate normal distribution and the GH distributions simplified the process.All proposed methodologies were illustrated with real data applications. Additionally, simulation studies based on the applications were conducted to assess the behavior of the estimation procedures, hypothesis tests, and influence diagnostics, providing support for its validity. The results showed accurate estimations that improved with larger sample sizes, as expected. Even in the presence of high levels of kurtosis, the symmetric GH models presented a better fit than the N-MRMME.Ultimately, this work contributes to the existing literature on measurement error models and generalized hyperbolic distributions
The intricate relationship between capillary refill time and systemic hemodynamics in septic shock
No full textThe emergence and validation of capillary refill time (CRT) as a resuscitation target together with its rapid kinetics of response to increases in systemic blood flow makes it the ideal variable to assess clinical reperfusion and the status of macro-to-microcirculatory coupling in septic shock. Moreover, previous studies have shown that resuscitation can be safely stopped after CRT normalization, thus decreasing the risk of over-resuscitation. From a physiological point of view, CRT is a complex variable integrating microvascular flow and reactivity. Additionally, it may be understood as a dynamic test that evaluates the preservation or disruption of normal responses of the microcirculation to maintain blood flow after transient ischemic challenges. The relationship between systemic hemodynamics and CRT is complex. Indeed, single time-point asssessments of CRT are not able to predict absolute cardiac output values and this is logical since they belong to different phsyiological categories. An abnormal CRT may be explained by insufficient macrohemodynamic resuscitation but also by several derangements at the microvascular level that may preclude CRT normalization, thus signaling a state of macro-to-microcirculatory uncoupling. CRT response to an acute fluid or mean arterial pressure challenge, may not only reveal the adequacy of systemic blood flow but also contribute to tailor interventions to personalize septic shock resuscitation. The lack of CRT response to these challenges discloses a more complex pathophysiological condition that is associated with higher mortality. Further research efforts should be focused on better understanding the factors associated with CRT non-response as a first step to develop a more phsyiologically-based resuscitation, that could eventually improve outcomes
Secuencia didáctica mediante libro álbum: El trabajo de la conciencia fonológica en estudiantes con TEL de escuelas rurales multigrado en el nivel de transición
No full textTesis (Magíster en Educación con mención en Didáctica del Lenguaje)--Pontificia Universidad Católica de Chile, 2025En el contexto rural de la educación chilena, y ante la necesidad de contar conpropuestas didácticas que aborden las habilidades pre-lectoras desde la literatura infantil,este estudio tuvo como objetivo aplicar una secuencia didáctica mediada por el libroálbum, orientada al desarrollo de habilidades pre-lectoras en estudiantes con TrastornoEspecífico del Lenguaje (TEL), según el modelo cognitivo de comprensión lectora deStahl y McKenna (2003). La intervención se llevó a cabo en un establecimiento rural dela comuna de Lago Ranco, con un índice de vulnerabilidad del 98%, en el nivel detransición, con una muestra de 22 estudiantes, de los cuales 5 presentan el diagnóstico.Para evaluar la propuesta, se aplicaron tres instrumentos: un cuestionario dirigido adocentes sobre el uso del libro álbum, una rúbrica de percepción docente y una secuenciadidáctica validada por expertas. Los resultados evidencian que la mediación del libroálbum favorece el acceso a habilidades de conciencia fonológica en estudiantes con TEL,integrando lo lúdico, lo visual y lo lingüístico como elementos clave. En particular, seobservaron avances en el reconocimiento de la rima, una de las tareas fonológicas máscomplejas según Defior (2000). Estos hallazgos contribuyen a visibilizar el valor de laliteratura en la educación inicial como herramienta para el desarrollo de habilidades prelectoras,promoviendo prácticas inclusivas contextualizadas a las realidades del aulamultigrado.2025-10-0
Hemodialysis for Severe Metabolic Alkalosis. A Comprehensive Review of Current Practices
No full textMetabolic alkalosis is very common in hospitalized patients and it is due to a negative H⁺ balance with base gain, especially HCO3−. When metabolic alkalosis is severe (pH ≥7.55) or extreme (pH >7.6), it is associated with extremely high morbidity and mortality, since, in addition to the underlying pathology, alkalemia itself generates serious organic repercussions and must be corrected promptly. Specifically, severe metabolic alkalosis is associated with increased adrenergic sensitivity, ionic hypocalcemia, hypokalemia, neuromuscular complications, myocardial and cerebral ischemia. In severe and extreme metabolic alkalosis, in addition to diagnosing and treating the underlying cause, it is necessary to promptly remove excess bases, which can be achieved through renal replacement therapy. Intermittent hemodialysis with low bicarbonate in the dialysate has proven to be very effective for its management. This narrative review explores literature reports where renal replacement therapy has been used to control severe metabolic alkalosis. It also analyzes side effects and response to therapy and attempts to provide recommendations regarding how to manage severe metabolic alkalosis with hemodialysis
Synthesis of Novel Chloro-Benzo [d]imidazole Regioisomers as Selective CB2 Receptor Agonists: Indirect Functional Evaluation and Molecular Insights
No full textThe cannabinoid type 2 receptor (CB2 receptor) has been extensively studied in recent years due to the benefits associated with its modulation, including the regulation of the inflammatory response, neuroimmunomodulatory properties, and antitumor effects, all with the advantage of lacking significant psychoactive effects. Herein, we report the design, synthesis, characterization, biological assays, and molecular modelling analyses of novel (5/6-chloro-2-aryl-1H-benzo [d]imidazol-1-yl)(4-methoxyphenyl)methanone and 5/6-chloro-1-(4-methoxybenzyl)-2-aryl-1H-benzo [d]imidazole regioisomers as potential cannabinoid type 2 receptor ligands. Methods: The compounds were evaluated for their presumed CB2 agonist activity using an indirect receptor-dependent apoptotic cell death assay exerted by cannabinoids, using the cell lines HEK293 (low CB1/CB2 expression), U-87 MG (high CB1 expression), and HL-60 (exclusive CB2 expression), and including the known cannabinoid ligands WIN-55,212-2 and AM630 as reference ligands. Flow cytometry was performed to assess apoptosis. Molecular docking and molecular dynamics simulations were used to explore ligand-receptor interactions at the CB2 active site. Results: Compounds 3a, 3b’, 3c, and 4b selectively reduced HL-60 cell viability, similar to WIN-55,212-2, while showing no toxicity toward HEK293 or U-87 MG cells. Flow cytometry indicated that compounds 3a and 3c induced apoptosis in HL-60 cells comparable to WIN-55,212-2. Computational studies suggested that both compounds bind within the CB2 receptor active site predominantly through π–π and hydrophobic interactions involving their benzo [d]imidazole cores, 2-aryl moieties, and 4-methoxybenzoyl scaffolds, resembling the binding patterns of established CB2 ligands. Conclusions: Compounds 3a and 3c exert selective cytotoxicity against HL-60 cells, likely via a CB2 agonist-mediated apoptotic mechanism. The applied combined experimental and computational approach provides a rapid, informative strategy for preliminary evaluation of CB2 ligands and guides subsequent detailed pharmacological studies
La zona costera como interfaz entre la escala oceánica y una escala de sitio: Un parque intermareal como medio para la protección del paisaje amenazado de Chañaral de Aceituno
No full textTesis (Magíster en Arquitectura del Paisaje)--Pontificia Universidad Católica de Chile, 2025La tesis explora la contradicción entre la relevancia oceánica de la Reserva NacionalPingüino de Humboldt y su relación con la Caleta Chañaral de Aceituno, ubicadas entre lasregiones de Coquimbo y Atacama. Esta área es reconocida por su alta biodiversidad marina ylos avistamientos de ballenas, atribuido a la geomorfología singular de un cañón submarino queparte en la Isla Damas al sur y culmina al norte entre la Isla Chañaral y la Caleta Chañaral deAceituno.La caleta enfrenta desafíos signifi cativos debido a la falta de infraestructura para elturismo y la pesca artesanal, lo que ha llevado a una percepción limitada del paisaje, centradaprincipalmente en el avistamiento de ballenas. Este caso es un reflejo de reiteradas situacionesa lo largo de las costas de Chile y del mundo, donde un sitio altamente turístico presenta unavisión parcial del paisaje que no se vincula con su relevancia ecosistémica global, saturando lasactividades en el espacio intermareal.Esta investigación comprende el paisaje de Chañaral de Aceituno a través de laexposición de sus escalas ecológicas para luego desarrollar un proyecto de arquitectura delpaisaje que actúe como mediador entre la biodiversidad marina y las dinámicas antrópicas. Sepostula que los bosques de macroalgas son un medio para habilitar, regenerar y cultivar la zonaintermareal materializando la escala oceánica en una escala de proyecto.Los objetivos incluyen valorar el paisaje de Chañaral de Aceituno desde su relevanciaecosistémica. Identifi car y caracterizar las escalas de paisaje para defi nir un espacio de mediaciónque ponga en valor su biodiversidad y su cultura, creando espacios de regeneración recreativosy productivos.La metodología abarca primero el estudio de la importancia del caso en el contextooceánico global, para luego realizar un análisis territorial mapeando los sistemas infraestructurales,culturales y naturales en su contexto interregional y así situar el área de actuación. En tercerlugar, se desarrolla un marco teórico bajo el cual se desarrolla la investigación que finalmentesustenta un proyecto de arquitectura del paisaje.Palabras Clave: Escalas de Paisaje, Parque Intermareal, Zona Costera, Caleta, PescaArtesanal, Arquitectura del Paisaj