Colecciones Institucionales

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11 beta-hydroxysteroid dehydrogenase activity in patients with hypertension and low plasma renin activity
(2002) Mosso, L; Carvajal, C; Campino, C; Rojas, A; Gonzalez, A; Barraza, A; Montero, J; Fardella, C; NCD Risk Factor Collaboration (NCD-RisC)
Background: Half of hypertensive patients with, low plasma renin activity have a primary hyperaldosteronism. Among the remaining half 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2) deficiency plays all important role. This enzyme catalyzes the conversion of cortisol to cortisone, avoiding the interaction of cortisol with, the mineralocorticoid receptor. If the enzyme fails, cortisol will stimulate sodium and water reabsorption and increase blood pressure. Aim: To determine biochemical alterations, suggestive of 11betaSHSD2 deficiency, in low-renin hypertensive patients. Patients and Methods: Twenty eight hypertensive patients with a plasma renin activity of less than 0.5 ug/ml/h and with a plasma aldosterone of less than 5 ng/dl were studied. Twenty eight normotensive patients were studied as controls. Serum. cortisol (RIA), cortisone (ELISA) and the serum cortisol/cortisone ratio were determined in all of them, between, 9 and 10 AM. Measurements were confirmed by high pressure liquid chromatography. The serum cortisol/cortisone ratio was considered abnormal when its Ln (cortisol/cortisone) value was over 2 standard deviations of the mean. Results: Serum cortisol was higher in hypertensive subjects than in controls (11.1 +/- 3.3 and 9.2 +/- 2.8 mug/dl, respectively; p <0.05). No differences were observed in serum cortisone (3.4 +/- 1.3 and 3.7 +/- 1.2 μg/dl, respectively). Four hypertensive subjects bad all abnormally high Ln (cortisol/cortisone) value (1.86; 1.73; 2.07 and 2.01, considering a normal value of less than 1.61). Conclusions: Four of 28 hypertensive subjects with, low plasma renin activity and aldosterone had biochemical alterations suggestive of 11.1βHSD2 deficiency.
11β-hydroxysteroid dehydrogenase activity in patients with hypertension and low plasma renin activityActividad de 11 beta hidroxiesteroide dehidrogenasa tipo 2 en hipertensos chilenos
(2002) Fardella B C.; Mosso G L.; Carvajal M C.; Campino J C.; Rojas O A.; González P A.; Barraza M A.; Montero L J.; NCD Risk Factor Collaboration (NCD-RisC)
Background: Half of hypertensive patients with low plasma renin activity have a primary hyperaldosteronism. Among the remaining half, 11β-hydroxysteroid dehydrogenase type 2 (11βHSD2) deficiency plays an important role. This enzyme catalyzes the conversion of cortisol to cortisone, avoiding the interaction of cortisol with the mineralocorticoid receptor. If the enzyme fails, cortisol will stimulate sodium and water reabsorption and increase blood pressure. Aim: To determine biochemical alterations, suggestive of 11βHSD2 deficiency, in low-renin hypertensive patients. Patients and Methods: Twenty eight hypertensive patients with a plasma renin activity of less than 0.5 ng/ml/h and with a plasma aldosterone of less than 5 ng/dl were studied. Twenty eight normotensive patients were studied as controls. Serum cortisol (RIA), cortisone (ELISA) and the serum cortisol/cortisone ratio were determined in all of them, between 9 and 10 AM. Measurements were confirmed by high pressure liquid chromatography. The serum cortisol/cortisone ratio was considered abnormal when its Ln (cortisol/cortisone) value was over 2 standard deviations of the mean. Results: Serum cortisol was higher in hypertensive subjects than in controls (11.1±3.3 and 9.2±2.8 μg/dl, respectively; p <0.05). No differences were observed in serum cortisone (3.4±1.3 and 3.7±1.2 μg/dl, respectively). Four hypertensive subjects had an abnormally high Ln (cortisol/cortisone) value (1.86; 1.73; 2.07 and 2.01, considering a normal value of less than 1.61). Conclusions: Four of 28 hypertensive subjects with low plasma renin activity and aldosterone had biochemical alterations suggestive of 11βHSD2 deficiency (Rev Méd Chile 2002; 130: 1201-8).
50-years of climate extreme indices trends and inventory of natural disasters in Chilean cities (1965-2015)
(Springer, 2019) Henríquez, Cristián; Qüense, Jorge; Villarroel, Claudia; Mallea, Cindy; Henríquez, Cristián; Romero, Hugo
A 22,000-Year Record of Monsoonal Precipitation from Northern Chile's Atacama Desert
(2000) Betancourt, Jl.; Latorre H., Claudio
A 7000‐year high‐resolution lake sediment record from coastal central Chile (Lago Vichuquén, 34°S): implications for past sea level and environmental variability
(2017) Frugone, M. J.; Latorre H., Claudio; Giralt, Santiago; Polanco Martínez, Josué; Bernárdez, Patricia; Oliva Urcía, Belén; Maldonado, Antonio; Carrevedo, María Laura; Moreno, Ana; Delgado Huertas, Antonio; Prego, Ricardo; Barreiro Lostres, Fernando; Valero Garcés, Blas
A Case Study on Fog/Low Stratus Occurrence at Las Lomitas, Atacama Desert (Chile) as a Water Source for Biological Soil Crusts
(2018) Lehnert, Lukas W.; Thies, Boris; Trachte, Katja; Achilles, Sebastian; Osses, Pablo; Baumann, Karen; Schmidt, Jakob; Samolov, Elena; Jung, Patrick; Leinweber, Peter; Karsten, Ulf; Buedel, Burkhard; Bendix, Joerg
A Consistently Processed Strong-Motion Database for Chilean Earthquakes
(Seismological Society of America, 2022) Castro, Sebastián; Benavente, Roberto; Crempien de la Carrera, Jorge; Candia, Gabriel; Llera Martin, Juan Carlos de la
© Seismological Society of America.Since the 1985 M 8.0 central Chile earthquake, national strong-motion seismic networks have recorded ten megathrust earthquakes with magnitudes greater than M 7.5 at the convergent margin, defined by the contact between the Nazca and South American plates. The analysis of these earthquake records have led to improved hazard analyses and design codes for conventional and seismically protected structures. Although strong-motion baseline correction is required for a meaningful interpretation of these records, correction methods have not been applied consistently in time. The inconsistencies between correction methods have been neglected in the practical use of these records in practice. Consequently, this work aims to provide a new strong-motion database for researchers and engineers, which has been processed by traceable and consistent data processing techniques. The record database comes from three uncorrected strong motion Chilean databases. All the records are corrected using a four-step novel methodology, which detects the P-wave arrival and introduces a baseline correction based on the reversible-jump Markov chain Monte Carlo method. The resulting strong motion database has more than 2000 events from 1985 to the date, and it is available to download at the Simulation Based Earthquake Risk and Resilience of Interdependent Systems and Networks (SIBER-RISK) project website.
A Functional Loss Assessment of a Hospital System in the Bio-Bio Province
(EARTHQUAKE ENGINEERING RESEARCH INST, 2012) Mitrani Reiser, Judith; Llera Martin, Juan Carlos de la; Mahoney, Michael; Holmes, William T.; Bissell, Rick; Kirsch, Thomas
The objectives of this study were to introduce a damage and loss-of-function survey tool that can be used to standardize future assessment of hospital performance, to assess the impact of the 2010 Chilean earthquake on the functions of the public hospital system in the Bio-Bio Province, and to translate these results as lessons that can be applied to U.S. hospitals. This study focused on damage to structural and nonstructural components, utility services, and equipment, as well as loss of supplies and personnel. Structural engineers completed a visual inspection of facilities, and hospital administrators were surveyed to assess the overall impact on operations. All hospitals lost communications, electrical power, and water for several days. All hospitals reported some physical damage although only one suffered significant structural damage. The lessons learned from Chile are applied to U.S. practice of hospital seismic mitigation. [DOI: 10.1193/1.4000044]
A global comparison of the climatic niches of urban and native tree populations
(2018) Kendal, Dave; Dobbs, Cynnamon; Gallagher, R. V.; Beaumont, L. J.; Baumann, J.; Williams, N. S. G.; Livesley, S. J.
A hydrogeochemistry and isotopic approach for the assessment of surface water-groundwater dynamics in an arid basin : the Limari watershed, North-Central Chile
(2015) Oyarzun, Ricardo; Jofre, Elizabeth; Morales, Paulina; Maturana, Hugo; Oyarzun, Jorge; Kretschmer, Nicole; Aguirre, Evelyn; Gallardo, Patricio; Toro, Luis E.; Muñoz Pardo, José Francisco; Aravena, Ramón
A macroeconomic disaster risk analysis: the case study of Chile
(ELSEVIER, 2022) Marulanda, M. C.; Llera Martin, Juan Carlos de la; Cardona, Omar Darío
From a macroeconomic perspective, the occurrence of disasters, especially high-impact events, can lead to financial stress in a country due to the sudden high demand for resources to restore affected exposed assets. Disaster risk is a sovereign risk and implies a non-explicit contingent liability that, in many cases, has a major impact on fiscal sustainability. Two risk composite indicators have been used to measure the impact that potential disasters can mean for a country: (i) The Disaster Deficit Index (DDI), which measures a country's financial capacity to cover the economic losses generated after the occurrence of high-impact events; and (ii) A complementary index (DDI'), which indicates the fraction that the expected annual loss would represent to the annual surplus of a country. This paper describes the overall macroeconomic impact of disasters and presents DDI results for Chile, which allows national-level decision-makers to understand the economic implications of disasters for the country and the need to consider this kind of information in the long-term policies. Results of the DDI for Chile illustrate that extreme disasters would imply the need for a significant amount of budgetary resources from the government. Estimated losses would be double the available budget resources and the financing of the recovery could mean restrictions to invest in other ongoing social and development needs of the country. This macroeconomic risk in Chile may be hedged by strategically setting up a risk financial structure based on adequate loss estimation criteria, using different available alternatives such as public and private assets insurance, disasters' reserves, contingency credits contracts, and investing in prevention and mitigation to reduce potential economic losses.
A model-data assessment of the role of Southern Ocean processes in the last glacial termination
(2016) Eichinger, Roland; Shaffer, Gary; Albarrán, Nelsón; Maisa Rojas; Lambert, Fabrice
A new aerobic chemolithoautotrophic arsenic oxidizing microorganism isolated from a high Andean watershed
(2018) Anguita, Javiera M.; Rojas, Claudia; Pastén González, Pablo Arturo; Vargas Cucurella, Ignacio Tomás; CEDEUS (Chile)
A physical model for dynamic analysis of wine barrel stacks
(2010) Candia,Gabriel; Llera Martin, Juan Carlos de la; Almazán Campillay, José Luis
A probabilistic seismic hazard assessment of southern Peru and Northern Chile
(2020) Das, Ranjit; Gonzalez, G.; Llera Martin, Juan Carlos de la; Sáez Robert, Esteban; Salazar, P.; Gonzalez, J.; Meneses, C.
Southern Peru and northern Chile (17–30°S, 67–74°W) make up a seismically active region due to the convergence of the Nazca Plate and the South American Plate. The region has experienced a number of destructive earthquakes and tsunamis over the past few centuries, which have caused loss of human life and significant damage to infrastructure, highlighting the importance of seismic hazard assessment in the region. In fact, a reliable seismic hazard assessment is critical for developing policies for seismic hazard mitigation and risk reduction. In this study, we performed a probabilistic seismic hazard assessment (PSHA) of the study area based on an earthquake catalog that was very carefully analyzed. In earlier studies, we demonstrated that inappropriate treatment of the earthquake catalog can result in a serious bias in evaluations of seismicity parameters (e.g., a bias of up to 42% in the “b” parameter of the Gutenberg–Richter law). To address this issue, we compiled a homogenous earthquake catalog consisting of 39,977 events during the 1513–2016 period and accounted for site-specific local effects by developing site-specific scaling relationships between different measures of magnitude (e.g., mb, Ms, MD) and moment magnitude (Mw). The study area was subdivided into 15 seismogenic zones, accounting for site-specific seismicity patterns. The parameters “a” and “b” of the Gutenberg–Richter law were estimated for each zone based on independent earthquake events. The PSHA was performed using a standard logic tree approach, which allowed us to systematically take into account the model-based uncertainty and its influence on the estimated ground motion parameters. Uniform hazard spectra for return periods of 475 and 2475 years were estimated for peak ground accelerations and spectral accelerations at 0.2 s and 1.0 s to meet the definitions of seismic hazards provided by the International Building Code (IBC, International Code Council [ICC], 2009). This study is expected to provide a basis for design maps for building codes and emergency planning.
A reanalysis of the Chilean ocean circulation: preliminary results for the region between 20 degrees S to 40 degrees S
(2017) Aiken, Christopher Michael
A review of the bipolar see-saw from synchronized and high resolution ice core water stable isotope records from Greenland and East Antarctica
(2015) Landais, A.; Masson Delmotte, V.; Stenni, B.; Selmo, E.; Roche, D. M.; Jouzel, J.; Lambert, Fabrice; Guillevic, M.; Bazin, L.; Arzel, O.; Vinther, B.; Gkinis, V.; Popp, T.
A simple model for estimating changes in rainfall erosivity caused by variations in rainfall patterns
(2018) Lobo, Gabriel P.; Bonilla Meléndez, Carlos Alberto
A simplified and versatile element model for elastomeric seismic isolation bearings
(SAGE PUBLICATIONS INC, 2021) Miranda Camus, Sebastián; Miranda, Eduardo; Llera Martin, Juan Carlos de la
A novel approach for two-dimensional modeling of elastomeric bearings using three springs in parallel is presented. This simplified element model considers as follows: (1) an elastoplastic spring with a smooth transition between branches; (2) a linear elastic spring; and (3) a non-linear elastic spring, and is fully defined by only six parameters. The main advantages of the simplified model are twofold: (1) versatility, as a single model is capable of accurately reproducing the main characteristics of the hysteretic behavior of different types of rubber-based seismic isolators, including low damping rubber bearings (LDRBs), high damping rubber bearings (HDRBs), and lead-core rubber bearings (LRBs) and (2) simplicity, as it requires fewer parameters and it is easier to calibrate from experimental cyclic test results than most currently available models. Model parameters' identification is illustrated using quasi-static cyclic and earthquake simulator tests of HDRBs and LRBs, demonstrating that the model shows a good agreement between the test-measured and model-predicted hysteretic behavior. Different objective functions are evaluated in the optimization procedure, and their effect on the identified parameters is studied and discussed. This practitioner-oriented model is particularly amenable for implementation in general-purpose structural analysis software. Its usage is strongly recommended as an initial-stage design tool to select the optimal isolation system for a specific project.
A simplified model for the analysis of free plan buildings using a wide-column model
(ELSEVIER SCI LTD, 2013) Encina Muñoz, Javier Andrés; Llera Martin, Juan Carlos de la
In early stages of the design of a free-plan building different structural layouts should be evaluated to achieve a satisfactory level of seismic performance. However, the urgency of initial stage decisions needed by architects and developers makes the use of complex 3D structural models impractical. For this reason, a tool that can evaluate with acceptable accuracy the expected seismic performance of these configurations is necessary. This paper introduces a simplified building model that includes the flexural contribution of the slabs, and models the shear wall cores using a wide column analogy that includes warping effects. The model introduces kinematic constraints to account for the interaction between walls and slabs. Comparison of modal and response-histories with those given by a 3D finite element model shows that the proposed model has good accuracy, leading to errors usually less than 15%. Finally, the model has been devised to include other shear-wall structural configurations, energy dissipation systems, and the inelastic behavior of walls. (C) 2013 Elsevier Ltd.. All rights reserved.

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