Carolina Martínez

Riesgo de tsunami en caleta Tubul, Región del Biobío: escenarios extremos y transformaciones territoriales posterremoto

RESUMEN Se analiza el riesgo de inundacion por tsunami para un evento extremo en la localidad de Tubul (37oS), Region del Biobio. Para el analisis de peligrosidad se determinaron tres escenarios asociados a los eventos tsunamigenicos locales de 1835 y 2010 a los cuales se aplico modelamiento numerico. Se incluyo el evento de 1877 para determinar los efectos de un tsunami lejano. Se analizo la vulnerabi-lidad en sus dimensiones fisica, socioeconomica y educativa. El tsunami de 1835 se determino como evento extremo, con alturas de inundacion de 10 m y cota de inundacion de 10 m. Se establecieron niveles de vulnerabilidad altos y medios explicados por la defi ciente materialidad de la vivienda y perfi l socioeconomico vulnerable de la poblacion, bajos niveles de escolaridad y reaccion frente a estos eventos. El riesgo natural obtenido se ubico en niveles altos para toda la localidad. Se contrastan los resultados con el Plan de Reconstruccion vigente. Palabras clave: Desastres naturales, vulnerabilidad, resiliencia, planifi cacion terri-torial.

Morfodinámica y evolución reciente de playa Tunquén, Chile central

Resumen es: Se presentan los estados morfodinamicos de playa Tunquen, zona distal de la ensenada de Algarrobo, Chile central y su relacion con cambios en la posicion...

Valor clínico y pronóstico de la corrección de atenuación con rayos X en la SPECT de perfusión miocárdica post-estrés

Resumen Objetivo El proposito del estudio fue validar la tecnica de correccion de atenuacion con rayos X, aplicada a la tomografia por emision de foton unico (SPECT) de perfusion miocardica post-estres. Material y metodos Se estudiaron 56 pacientes con sospecha clinica de cardiopatia isquemica y sin antecedentes de infarto de miocardio ni de revascularizacion coronaria. A todos se les realizo una tomografia por emision de foton unico (SPECT) de perfusion miocardica post-estres ergometrico (38) o farmacologico (18). El tiempo medio de seguimiento clinico fue de 18,6 meses. Se valoraron los estudios tras su reconstruccion mediante la tecnica de retroproyeccion filtrada, y despues de aplicar la tecnica de correccion de atenuacion con rayos X. Los resultados obtenidos se relacionaron con el diagnostico clinico final. Resultados Once estudios no corregidos fueron normales y 45 mostraron defectos de perfusion. Tras la correccion de atenuacion, se observo la ausencia de defectos significativos de perfusion en 24 casos (42,9 % del total) y finalmente se descarto cardiopatia isquemica en 22. Se observo una mayor frecuencia de normalizacion del estudio en hombres (p = 0,048; odds ratio = 2.923), pero este hecho no mostro correlacion significativa con las siguientes variables: probabilidad pre-test de cardiopatia isquemica, indice de masa corporal superior a 30, presencia o ausencia de factores de riesgo cardiovascular y edad del paciente. Conclusiones La aplicacion de la tecnica de correccion de atenuacion con rayos X hubiera permitido obviar la realizacion de un estudio de perfusion de reposo en el 42,9 % de los pacientes, sin modificarse aparentemente la seguridad diagnostica del test. Este hecho se observo con mayor frecuencia en hombres. El metodo parece ser seguro, asi como tiempo y coste-efectivo.

[Clinical and prognostic value of X-ray based attenuation correction in post-stress myocardial perfusion SPECT].

OBJECTIVE The purpose of the study was to validate the X-ray-based attenuation correction technique applied to post-stress myocardial perfusion single photon emission computed tomography (SPECT). MATERIALS AND METHODS Fifty-six patients with clinically suspected ischemic heart disease and no history of myocardial infarction or coronary revascularization were studied. All patients underwent a myocardial perfusion SPECT after exercise (38) or pharmacological stress (18). Mean clinical follow-up time was 18.6 months. Studies were assessed after reconstruction using the filtered back projection technique and after application of the X-ray-based attenuation correction technique, and the results obtained were related to the final clinical diagnosis. RESULTS Eleven uncorrected studies were normal, while 45 studies showed perfusion defects. After attenuation correction, absence of significant perfusion defects was observed in 24 cases (42.9 % of all cases), and ischemic heart disease was finally ruled out in 22 cases. A greater study normalization rate was seen in men (p = 0.048; odds ratio = 2,923), but this fact was not shown to be significantly correlated to the following variables: pre-test probability of ischemic heart disease, body mass index greater than 30, presence of cardiovascular risk factors or otherwise, and age. CONCLUSIONS Application of the X-ray-based attenuation correction technique would have allowed for obviating the conduct of a resting perfusion study in 42.9 % of patients without apparently changing the diagnostic safety of the test. This fact was seen more frequently in men. This method seems to be both safe and time- and cost-effective.

Shoreline changes in Concón and Algarrobo bays, central Chile, using an adjustment model

Adjustment models for both Algarrobo and Concon bays, central Chile, are presented herein; the results show a nearly logarithmic spiral shape for the shore. Spatial-temporal variations in the shorelines of both bays were found based on aerial photographs from different years. The results indicate important variations in the relative position of the Concon Bay shoreline between 1945 and 2006, with extreme oscillations (-368 to 123.8 m) only occurring in the proxi- mal zone, where the Aconcagua Estuary is located. On the other hand, the spatial-temporal variations in the Algarrobo Bay shoreline between 1967 and 2006 are moderate (131 in the proximal and -73 in the distal zone). Whereas Concon Bay exhibits a stable state of equilibrium for the past 60 years, if the estuary zone is excluded, Algarrobo Bay presents a stable state with a tendency for growth in the proximal zone and retreat in the distal zone. The results are discussed in terms of coastal changes associated with highly urbanized shorelines and applications for coastal area management that are derived from the models.

Geomorphological changes and tsunami risk in a coastal wetland post-earthquake in south-central Chile

O of the major agricultural productions in Indonesia is rice production, on which negative climate change impact is anticipated. To assess the impact, simulating water budget and its effect on rice production is recommended. In this study, we developed a coupling model of hydrology and rice growth, and simulated rice yield under some GCM scenarios. After downscaling and bias-correcting GCMs, a hydrological model, the Water and Energy Budget-based Distributed Hydrological Model (WEB-DHM), simulated water flow and soil moisture content in total 60,000 km2 of Musi river basin by 500 m-mesh. Each mesh was categorized such as rainfed rice, shrub and so on based on governmental land use map. Rice growth and yield was simulated by a model, Simulation Model for Rice Weather Relations for rainfed (SIMRIW-Rainfed) based on the weather and soil moisture by WEB-DHM. Weather data from 1985 to 2012 was used for model calibration and validation as the present climate. The simulated rice yield under present climate was well consistent with the statistical data for rice production. Decrease in rice yield was simulated in rainfed paddy fields due to drought. Rice yield in the future (2050-2065) was slightly increased under GCM scenario gfdl_cm2_0, but largely decreased under gfdl_cm2_1. Shift of rainy season is one of the reasons of large decrease under gfdl_cm2_1, change of planting time and duration is one of adaptive strategies.