Publicaciones académicas

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Esta colección incluye artículos de profesores de la Pontificia Universidad Católica de Chile, publicados en revistas nacionales y extranjeras.

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11β-hydroxysteroid dehydrogenase type 2 polymorphisms and activity in a Chilean essential hypertensive and normotensive cohort.
(2012) Campino, Carmen; Quinteros, Hector; Owen, Gareth I.; Carvajal, Cristian A.; Morales, Mauricio; Olivieri, Oliviero; Guidi, Giancesare; Faccini, Giovanni; Pasini, Francesco; Baudrand, Rene; Padilla, Oslando; Valdivia, Carolina; Thichauer, Juan; Lagos, Carlos F.; Kalergis, Alexis M.; Fardella, Carlos E.
BACKGROUND: 11β-hydroxysteroid dehydrogenase type 2 enzyme (11β-HSD2) inactivates cortisol (F) to cortisone (E); its impairment is associated with hypertension. We reported that 15.7% of the Chilean essential hypertensives possessed a high F/E ratio suggesting a partial deficit in 11β-HSD2 activity. It has been reported that the G534A(Glu178/Glu) polymorphism in the HSD11B2 gene is associated with hypertension. Investigate the frequency of the G534A polymorphism and its correlation with the glucocorticoid profile in Chilean essential hypertensive and normotensive subjects. METHODS: Essential hypertensive outpatients (n = 232) and normotensive subjects (n = 74) were recruited. A change in the AluI restriction enzyme digest pattern, caused by the presence of the G534A polymorphism, was utilized to screen DNA isolated from leukocytes within the cohort before confirmation by sequencing. Plasma renin activity (PRA), serum aldosterone, F, and E were measured by radioimmunoassay. Urinary tetrahydrocortisol (THF), 5α-tetrahydrocortisol (5α-THF), and tetrahydrocortisone (THE) were measured by gas chromatography-mass spectrometry. RESULTS: G534A polymorphism frequency was similar between hypertensive patients (19 of 232; 8.2%) and normotensive subjects (7 of 74; 9.5%). When categorized by presence or absence of the G534A polymorphism, no significant differences in the serum F/E ratio or other measured biochemical variables were detected. Despite a previous report that the G534A polymorphism is associated with a neighboring C468A (Thr156/Thr) polymorphism, analysis within our cohort showed that only one patient in each group presented with this double polymorphism. CONCLUSIONS: We report the frequency of the G534A polymorphism in the Spanish-Amerindian population. No correlation was detected between this polymorphism and the presence of hypertension and biochemical parameters in this Chilean cohort.
20(th) Congress of the Chilean Association of Automatic Control, ACCA-2012
(2014) Perez Correa, Jose Ricardo
23-Level Inverter for EVs Using Only One Power Supply and Series Active Filters
(2012) Pereda Torres, Javier
25 Hydroxy Vitamin D Level, Bone Health, Vitamin D and Calcium Intake in Chilean Patients with Phenylketonuria and Hyperphenylalaninemias
(2021) Leiva, Carla; Bravo Jiménez, Paulina; Arias, Carolina; Cabello, Juan; Leal-Witt, María Jesús; Salazar Silva, Florencia; Cornejo, Verónica
It has been shown that there is a decrease in the concentrations of 25 hydroxyvitamin D (25-OHD) and bone mineral density (BMD) in patients with phenylketonuria (PKU) in their follow-up. Our objective was to determine concentrations of 25-OHD in subjects with PKU and hyperphenylalaninemia (HPA). Transversal analytical study considered three groups: G1-PKU with neonatal diagnosis and formula intake without Phe; G2-HPA, without specific treatment and G3-C control group. Sixteen patients per group (aged 6-23) were included. Levels of 25-OHD, lumbar spine (L2-L4), femur and total BMD, intact parathormone (PTH) and vitamin D (VitD) and calcium intake were calculated. The Kruskal-Wallis statistical test was applied (p-value<0,05). Significant differences were detected in concentrations of 25-OHD between G1-PKU and G2-HPA (38.9 ng/mL; 28 ng/mL, respectively) (NV: >30 ng/mL). G1-PKU had a higher intake of VitD, with differences among groups. There were no significant differences among groups in relation to BMD and intact PTH. In conclusion, G1-PKU under treatment and with good adherence, does not present VitD deficiency and no BMD alterations are observed. In contrast, G2-HPA had a lower intake of VitD and decreased 25-OHD concentrations which could affect the bone architecture in the long term. Further studies on the G2-HPA are suggested.
2D materials for Tribo-corrosion and -oxidation protection: a review
(Elsevier B.V., 2024) Ramteke, Sangharatna M.; Walczak, Magdalena; De Stefano, Marco; Ruggiero, Alessandro; Rosenkranz, Andreas; Marian, Max
The recent rise of 2D materials has extended the opportunities of tuning a variety of properties. Tribo-corrosion, the complex synergy between mechanical wear and chemical corrosion, poses significant challenges across numerous industries where materials are subjected to both tribological stressing and corrosive environments. This intricate interplay often leads to accelerated material degradation and failure. This review critically assesses the current state of utilizing 2D nanomaterials to enhance tribo-corrosion and -oxidation behavior. The paper summarizes the fundamental knowledge about tribo-corrosion and -oxidation mechanisms before assessing the key contributions of 2D materials, including graphene, transition metal chalcogenides, hexagonal boron nitride, MXenes, and black phosphorous, regarding the resulting friction and wear behavior. The protective roles of these nanomaterials against corrosion and oxidation are investigated, highlighting their potential in mitigating material degradation. Furthermore, we delve into the nuanced interplay between mechanical and corrosive factors in the specific application of 2D materials for tribo-corrosion and -oxidation protection. The synthesis of key findings underscores the advancements achieved through integrating 2D nanomaterials. An outlook for future research directions is provided, identifying unexplored avenues, and proposing strategies to propel the field forward. This analysis aims at guiding future investigations and developments at the dynamic intersection of 2D nanomaterials, tribo-corrosion, and -oxidation protection.
30 years from the Caracas Declaration: the situation of psychiatric hospitals in Latin America and the Caribbean prior, during and after the COVID-19 pandemic
(2021) Mascayano, Franco; Alvarado, Rubén; Martínez-Viciana, Carmen; Irarázaval, Matías; Durand-Arias, Sol; Freytes, Marcela; Montenegro Cortés, Cristián; Susser, Ezra; Bruni, Andrea
Latin America and the Caribbean (LAC) recently celebrated 30 years from the Caracas Declaration, which, in 1990, set forth the principles to transition from hospital-based mental health care into community mental health services [1]. Since then, significant efforts have been made to reduce the number of psychiatric hospital beds, increase mental health teams within general hospitals, integrate mental health into primary care, implement outpatient mental health facilities, and encourage the participation of community members in the provision and implementation of mental health care [2]. Nonetheless, progress has been uneven across countries [2]. Many large psychiatric hospitals (PHs) still exist and consume most of the scanty national mental health budgets [3]. Moreover, PH residents in LAC were poor and socially excluded even before the COVID-19 pandemic hit. The COVID-19 pandemic has worsened the living conditions of these people, especially in resource-constrained settings.
3D imaging techniques for improved colonoscopy.
(2014) Durr, Nicholas J.; González, Germán; Parot Fernández, Vicente José
3D joint T 1/T 1 ρ/T 2 mapping and water-fat imaging for contrast-agent free myocardial tissue characterization at 1.5T.
(2025) Crabb, Michael G.; Kunze, Karl P.; Littlewood, Simon J.; Tripp, Donovan; Fotaki, Anastasia; Prieto Vásquez, Claudia; Botnar, René Michael
PURPOSE: To develop a novel, free-breathing, 3D joint T 1 $$ {T}_1 $$ / T 1 ρ $$ {T}_{1\rho } $$ / T 2 $$ {T}_2 $$ mapping sequence with Dixon encoding to provide co-registered 3D T 1 $$ {T}_1 $$ , T 1 ρ $$ {T}_{1\rho } $$ , and T 2 $$ {T}_2 $$ maps and water-fat volumes with isotropic spatial resolution in a single ≈ 7 $$ \approx 7 $$ min scan for comprehensive contrast-agent-free myocardial tissue characterization and simultaneous evaluation of the whole-heart anatomy. METHODS: An interleaving sequence over 5 heartbeats is proposed to provide T 1 $$ {T}_1 $$ , T 1 ρ $$ {T}_{1\rho } $$ , and T 2 $$ {T}_2 $$ encoding, with 3D data acquired with Dixon gradient-echo readout and 2D image navigators to enable 100 % $$ 100\% $$ respiratory scan efficiency. Images were reconstructed with a non-rigid motion-corrected, low-rank patch-based reconstruction, and maps were generated through dictionary matching. The proposed sequence was compared against conventional 2D techniques in phantoms, 10 healthy subjects, and 1 patient. RESULTS: The proposed 3D T 1 $$ {T}_1 $$ , T 1 ρ $$ {T}_{1\rho } $$ , and T 2 $$ {T}_2 $$ measurements showed excellent correlation with 2D reference measurements in phantoms. For healthy subjects, the mapping values of septal myocardial tissue were T 1 = 1060 ± 48 ms $$ {T}_1=1060\pm 48\kern0.2778em \mathrm{ms} $$ , T 1 ρ = 48 . 1 ± 3 . 9 ms $$ {T}_{1\rho }=48.1\pm 3.9\kern0.2778em \mathrm{ms} $$ , and T 2 = 44 . 2 ± 3 . 2 ms $$ {T}_2=44.2\pm 3.2\kern0.2778em \mathrm{ms} $$ for the proposed sequence, against T 1 = 959 ± 15 ms $$ {T}_1=959\pm 15\kern0.2778em \mathrm{ms} $$ , T 1 ρ = 56 . 4 ± 1 . 9 ms $$ {T}_{1\rho }=56.4\pm 1.9\kern0.2778em \mathrm{ms} $$ , and T 2 = 47 . 3 ± 1 . 5 ms $$ {T}_2=47.3\pm 1.5\kern0.2778em \mathrm{ms} $$ for 2D MOLLI, 2D T 1 ρ $$ {T}_{1\rho } $$ -prep bSSFP and 2D T 2 $$ {T}_2 $$ -prep bSSFP, respectively. Promising results were obtained when comparing the proposed mapping to 2D references in 1 patient with active myocarditis. CONCLUSION: The proposed approach enables simultaneous 3D whole-heart joint T 1 $$ {T}_1 $$ / T 1 ρ $$ {T}_{1\rho } $$ / T 2 $$ {T}_2 $$ mapping and water/fat imaging in ≈ $$ \approx $$ 7 min scan time, demonstrating good agreement with conventional mapping techniques in phantoms and healthy subjects and promising results in 1 patient with suspected cardiovascular disease.
3D non-destructive evaluation techniques for wood analysis
(2014) Paulina Fernández, M.; Tejos Nunez, Cristian Andres; Rojas, G.; Lillo, I.; Guesalaga, A.; Irarrázaval, P.
90 Winds, Some X-rays, and Sgr A* Walk Into VR...
(2021) Russell, C. T.; Luco Korn, José Baltasar; Sepúlveda, Miguel; Cuadra, Jorge; Calderón Espinoza, Diego Nicolás; Wang, Q. Daniel
Virtual reality (VR) provides a new tool for exploring astrophysical simulations. Our case study is hydrodynamic simulations of the central parsec of the Galactic center, which models 25 Wolf-Rayet (WR) stars that are orbiting Sgr A* while ejecting their stellar winds. The VR program we are developing allows users to fully immerse themselves in a simulation snapshot, allowing them full control over their position and viewing orientation. The highlight result so far is exquisite views of material inspiraling towards the black hole. We also present a new hydrodynamic simulation that adds 65 O and 'S' stars, which causes a reduction in thermal X-ray emission in the vicinity of Sgr A* compared to the WR-only simulations....
El 98, hoy, en Chile
(1999) Sagredo Baeza, Rafael
A Bias Network Approach (BNA) to Encourage Ethical Reflection Among AI Developers
(2024) Arriagada Bruneau, Gabriela; Lopez, Claudia; Davidoff, Alexandra
We introduce the Bias Network Approach (BNA) as a sociotechnical method for AI developers to identify, map, and relate biases across the AI development process. This approach addresses the limitations of what we call the "isolationist approach to AI bias," a trend in AI literature where biases are seen as separate occurrences linked to specific stages in an AI pipeline. Dealing with these multiple biases can trigger a sense of excessive overload in managing each potential bias individually or promote the adoption of an uncritical approach to understanding the influence of biases in developers' decision-making. The BNA fosters dialogue and a critical stance among developers, guided by external experts, using graphical representations to depict biased connections. To test the BNA, we conducted a pilot case study on the "waiting list" project, involving a small AI developer team creating a healthcare waiting list NPL model in Chile. The analysis showed promising findings: (i) the BNA aids in visualizing interconnected biases and their impacts, facilitating ethical reflection in a more accessible way; (ii) it promotes transparency in decision-making throughout AI development; and (iii) more focus is necessary on professional biases and material limitations as sources of bias in AI development.
A Call to Contextualize Public Opinion-Based Research in Political Communication
(2019) Rojas, Hernando; Valenzuela Leighton, Sebastián Andrés
A Case Analysis Methodology to Guide Decision Making in the Schooling Context
(Springer Cham, 2023) Marchant Araya, María Paola; Förster Marín, Carla
This chapter addresses a look at the analysis of problems in educational contexts oriented towards evidence-based decision making. Its purpose is to provide management and research teams with a tool to systematize information from an institution, a program or project, articulate said information with the conceptual frameworks associated with the subject, and raise critical knots based on reflective analysis and propose solutions and actions for change. This method defines three stages: the construction of the case, the analysis, and the improvement proposal. For each stage, its characteristics, how to carry them out and a real example are developed. Finally, some ethical considerations that must be safeguarded are indicated, what elements the report must have and some limitations to consider.
A column generation approach to intraday scheduling of chemotherapy patients
(2023) Lyon Bossay, Gabriel; Cataldo Cornejo, Alejandro; Angulo, Gustavo; Rey, Pablo; Sauré, AntoineLyon Bossay, Gabriel; Cataldo Cornejo, Alejandro; Angulo, Gustavo; Rey, Pablo; Sauré, Antoine
Chemotherapy scheduling at cancer treatment centres is a complex problem due to high and grow-ing demand, diversity of treatment protocols, limitations on resources and the need to coordinatetreatment session times with laboratory preparation of medication. Over a given planning horizon,treatment centres assign patients first to specific days (interday scheduling) and then to specifictimes within each day (intraday scheduling), the latter process including the definition of medicationpreparation time. This paper addresses the intraday scheduling problem using an integer program-ming model that attempts to schedule all patients assigned to the horizon, and the preparation ofthe medication to be administered, simultaneously. The linear relaxation of the model formulation,which is based on treatment patterns, is solved using column generation. The proposed approachallows for medication preparation on the day of treatment or a previous day subject to time slot avail-ability. A case study is conducted using actual data from a Chilean cancer centre to compare throughsimulationtheschedulesgeneratedbytheproposedapproachandthecentre’smanualmethod.Theresults show that the proposed approach performs better on makespan, treatment chair occupancy,number of overtime hours and finding solutions at high demand levels.
A Community Disaster Resilience Index for Chile
(2023) Bronfman, Nicolás; Castañeda González, Javiera Valentina; Guerrero Mancilla, Nikole Fernanda; Cisternas, Pamela; Repetto Lisboa, Paula Beatriz; Martínez, Carolina; Chamorro Giné, Marcela AlondraBronfman, Nicolás; Castañeda González, Javiera Valentina; Guerrero Mancilla, Nikole Fernanda; Cisternas, Pamela; Repetto Lisboa, Paula Beatriz; Martínez, Carolina; Chamorro Giné, Marcela Alondra
Although Chile is one of the countries most exposed to natural hazards, to date there is no national index that shows the differences in resilience levels within the country. This study develops a community resilience index on a national scale based on the Baseline Resilience Community (BRIC) index. The BRIC index for Chile was built with 49 indicators, from different sources at the district level. Our results determined that resilience is not distributed homogeneously throughout the country. The highest levels of resilience are concentrated in the central macro-zone. In comparison, the extreme zones of Chile focus close to 90% of their population in the lowest levels, accounting for an uneven distribution of resources and services that impact resilience levels. These differences were mainly explained by indicators such as the percentage of the population without a health insurance system, the percentage of the population without internet access, and the percentage of electoral participation, among others. The results demonstrate that the BRIC model can be successfully implemented to assess community resilience in Chile and suggests the possibility of targeting resources and strategies to increase resilience in areas with the lowest levels of community resilience.
A comparative analysis of University Sustainable Travel Plans – Experience from Australia
(2023) Nelson J. D.; Balbontin Tahnuz, Camila; Hensher D. A.; Beck M.
Travel Demand Management (TDM) initiatives are widely applied by transport planners to establish and enable appropriate use of critical transport infrastructure. Less attention has been given to the specific case of TDM in an education precinct (university) context. Travel Plans have been promoted as a means for an organisation to encourage sustainable travel choices by their employees, visitors and customers. This paper offers an empirical contribution to the literature through a comparative qualitative evaluation of selected University Sustainable Travel Plans (USTPs) in Australia to identify the most important questions that a USTP should address explicitly. The evaluation comprised identification of a set of evaluation questions, completion of a template for each USTP considered and application of a simple scoring exercise. We also identify TDM measures that have been introduced as part of a USTP in response to the typical travel patterns exhibited in university settings. A contribution of this paper is to create a means of comparison of USTPs and to establish the components of a comprehensive travel plan.
A comparative analysis of virial black hole mass estimates of moderate-luminosity active galactic nuclei using Subaru/FMOS.
(2013) Matsuoka, K.; Treister, Ezequiel; Silverman, J. D.; Schramm, M.; Steinhardt C. L.; Nagao, T.; Kartaltepe, J.; Sanders, David B.; Hasinger, G.; Akiyama, M.
A Comparison of Energy Efficiency Certification in Housing: A Study of the Chilean and Spanish Cases
(2019) Sanhueza Durán, Francisco; Gómez Soberón, José M.; Valderrama Ulloa, Claudia; Ossio Castillo, Felipe Antonio
Faced with implementing policies that seek to improve the energy efficiency of housing and reduce the impact of CO2 emissions, several countries are introducing (unilaterally or by international agreement) energy certification systems that allow the effects of these policies to be evaluated. This study aims to compare the energy efficiency certification systems in Spain and Chile, identifying convergent and divergent parameters, enabling the existing gaps to be identified and improvements noted for both systems. To do so, 20 sample dwellings in Santiago de Chile were evaluated, along with the local calculating tools in both countries. The analysis considered the aspects of regulation, its reach, the characterization of the models and the necessary indicators. The comparison identified, among others, differences such as obligatory implementation of the system, a study of the existing buildings in the focus area, the prevailing indicators for evaluating the effects of the buildings, the low incidence of mixed energy systems in the Chilean system and the possibility of proposing and evaluating improvements in the Spanish system. As a result, higher energy requirements and greater CO2 emissions were identified in the Chilean system, reaching differences of 42 kWh/m2/year in consumption and 14 kgCO2/ m2/year in emissions with regard to the Spanish qualification. The results of this comparison have facilitated the identification of improvements that will increase the evaluation standards of the Chilean system.
A comparison of packed-bed flow topologies for high-temperature thermal energy storage under constrained conditions
(2024) Ignacio Calderón-Vásquez; Cardemil Iglesias, Jose Miguel

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