Browsing by Author "Leon, Jorge"

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    Analysis of the effects of urban micro-scale vulnerabilities on tsunami evacuation using an agent-based model - case study in the city of Iquique, Chile
    (2024) Cienfuegos, Rodrigo; Alvarez, Gonzalo; Leon, Jorge; Urrutia, Alejandro; Castro, Sebastian
    The occurrence of mega-tsunamis over the last couple of decades has greatly increased the efforts of the research community and practitioners to work hand in hand to reduce risks from these highly destructive threats. Protecting the population through evacuation is the best alternative for avoiding loss of life in the wake of the occurrence of a tsunamigenic earthquake. Therefore, guaranteeing the proper state of evacuation routes is very important to ensuring appropriate movement to the safe zones. This study carries out a detailed analysis of possible evacuation scenarios, considering the actual state of the escape routes of Iquique, a Chilean city prone to tsunamis, with a substantial number of urban micro-scale vulnerabilities, i.e., elements that obstruct or complicate pedestrian flow. The quantification of the delay in evacuation processes resulting from the presence of urban micro-vulnerabilities is carried out through micro-scale agent-based model (ABM) simulations. In addition, these results are integrated with high-resolution tsunami inundation simulations, allowing for an estimation of the potential number of people that the tsunami may reach under different scenarios by emulating the dynamics and behavior of the population and the decision-making regarding the starting time of the evacuation.
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    Children's views on evacuation drills and school preparedness: Mapping experiences and unfolding perspectives
    (2018) Vasquez, Andrea; Marinkovic, Katitza; Bernales, Margarita; Leon, Jorge; Gonzalez, Juan; Castro, Sebastian
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    Color development and acrylamide content of pre-dried potato chips
    (ELSEVIER SCI LTD, 2007) Pedreschi, Franco; Leon, Jorge; Mery, Domingo; Moyano, Pedro; Pedreschi, Romina; Kaack, Karl; Granby, Kit
    The objective of this work was to study the development of color formation in pre-dried potato slices during frying and acrylamide formation in the final potato chips. Color measurement was done by using an inexpensive computer vision technique which allowed quantifying representatively and precisely the color of complex surfaces such as those of potato chips in L*a*b* units from RGB images. Prior to frying, potato slices (Desiree variety, diameter: 37 mm, width: 2.2 mm) were blanched in hot water at 85 degrees C for 3.5 min. Unblanched slices were considered as the control. Slices of the same dimensions were blanched as in the previous step, and then air-dried until reaching a moisture content of 60% (wet basis). These samples were called pre-dried potato slices. Potato slices were fried at 120 degrees C, 140 degrees C, 160 degrees C and 180 degrees C until reaching moisture contents of similar to 1.8% (total basis) for color quantification. Acrylamide concentration was determined only in final chips fried at 120 degrees C, 150 degrees C and 180 degrees C and compared with that of two brands of commercial chips produced in Chile (Moms and Frito Lay). Color values in L*a*b* units were recorded at different sampling times during frying at the four mentioned temperatures using the total color difference parameter (Delta E). Pre-drying did not affect the color of potato chips considerably when compared against blanched chips; however when fried at 180 degrees C, pre-dried potato chips present 44%, 22%, 44% lower acrylamide content than that of the control, Moms and Frito Lay chips, respectively. (c) 2006 Elsevier Ltd. All rights reserved.
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    Color measurement in L*a*b* units from RGB digital images
    (ELSEVIER, 2006) Leon, Katherine; Mery, Domingo; Pedreschi, Franco; Leon, Jorge
    The superficial appearance and color of food are the first parameters of quality evaluated by consumers, and are thus critical factors for acceptance of the food item by the consumer. Although there are different color spaces, the most used of these in the measuring of color in food is the L*a*b* color space due to the uniform distribution of colors, and because it is very close to human perception of color. In order to carry out a digital image analysis in food, it is necessary to know the color measure of each pixel on the surface of the food item. However, there are at present no commercial L*17*b* color measures in pixels available because the existing commercial colorimeters generally measure small, non-representative areas of a few square centimeters. Given that RGB digital cameras obtain information in pixels, this article presents a computational solution that allows the obtaining of digital images in L*a*b* color units for each pixel of the digital RGB image. This investigation presents five models for the RGB -> L*a*b* conversion and these are: linear, quadratic, gamma, direct, and neural network. Additionally, a method is suggested for estimating the parameters of the models based on a minimization of the mean absolute error between the color measurements obtained by the models, and by a commercial colorimeter for uniform and homogenous surfaces. In the evaluation of the performance of the models, the neural network model stands out with an error of only 0.93%. On the basis of the construction of these models, it is possible to find a L*a*b* color measuring system that is appropriate for an accurate, exacting and detailed characterization of a food item, thus improving quality control and providing a highly useful tool for the food industry based on a color digital camera. (c) 2006 Elsevier Ltd. All rights reserved.
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    Development of a computer vision system to measure the color of potato chips
    (ELSEVIER, 2006) Pedreschi, Franco; Leon, Jorge; Mery, Domingo; Moyano, Pedro
    The objective of this research was to design and implement an inexpensive computer vision system for measuring the color of a highly heterogeneous food material not only in shape as well in color such as potato chips in L*a*b* units from RGB images. The system was composed of (i) a digital color camera for acquiring the images in a digital format, (ii) a computer for storage the images, (c) image analysis routines integrated into a software programmed in Matlab that converts the color RGB of the food image into L*a*b* units. In this way the color of potato chips can be calculated in L*a*b* units over representative areas and in a reproducible way. The kinetics of color changes in potato slices during frying at four temperatures was followed using the implemented computer vision system (CVS). Color values in L*a*b* units were recorded at different sampling times during frying at the four oil temperatures using the total color change parameter (AE). Chips fried at higher temperatures get darker as expected and showed by the CVS. The implemented computer vision system can be used to study as well foods different from potato chips by selecting their proper settings for image acquisition and digital image processing. (c) 2006 Elsevier Ltd. All rights reserved.
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    From urban form analysis to metrics for enhancing tsunami evacuation: Lessons from twelve Chilean cities
    (ELSEVIER, 2021) Leon, Jorge; Vicuna, Magdalena; Ogueda, Alonso; Guzman, Simon; Gubler, Alejandra; Mokrani, Cyril
    In the case of near-field tsunami emergencies, evacuation is considered the most important and effective method to save human lives. While significant efforts have been carried out to examine the relationships between urban forms and tsunami evacuation, challenges remain on delivering evidence-based urban design strategies, principles or metrics that could be applied by decision-makers to guide the physical development or retrofitting of tsunami-prone coastal communities around the world. In this paper, we propose a methodology that combines tsunami flood and evacuation modelling with statistical analysis, to examine the pedestrian evacuation potential of 67 urban samples extracted from 12 case studies in Chile. Our findings show that urban form parameters like the number of exit points out of an endangered area, the mean distance from the street network to these points, and the population density, can have a noticeable impact on tsunami evacuation times, which nonetheless is significantly dependent on the evacuees & rsquo; departure time. Moreover, we demonstrate that Chilean urban coastal development has been noticeably carried out through grid-like form patterns that might contribute to hinder evacuation in case of a tsunami emergency.
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    Mode of delivery and antenatal steroids and their association with survival and severe intraventricular hemorrhage in very low birth weight infants
    (2016) Hubner, M. E.; Ramirez, R.; Burgos, J.; Dominguez, A.; Tapia, J. L.; Colantonio, Guillermo; Zapata, Jorge; Perez, Gaston; Ana Pedraza, Susana Garcia; Kurlat, Isabel; Di Siervi, Oscar; Escarate, Adriana; Mariani, Gonzalo; Maria Ceriani, Jose; Fernandez, Silvia; Fustinana, Carlos; Brener, Pablo; Edwards, Eleonora; Tavosnaska, Jorge; Roldan, Liliana; Sexer, Hector; Saa, Gladys; Sabatelli, Debora; Laura Gendra, Maria; Fernanda Buraschi, Maria; Molina, Paula; Daniel, Agost; Morganti, Federico; Fontana, Adriana; Chandias, Daniela; Rinaldi, Monica; Grandi, Carlos; Rojas, Elio; Solana, Claudio; Nieto, Ricardo; Meritano, Javier; Larguia, Miguel; Kasten, Laura; Cuneo, Lucrecia; Decaro, Marcelo; Cracco, Lionel; Bassi, Gustavo; Jacobi, Noemi; Brum, Andrea; Vain, Nestor; Aguilar, Adriana; Guerrero, Miriam; Szyld, Edgardo; Escandar, Alcira; Abdala, Daniel; Guida, Martin; Ferrin, Lucila; Roge, Horacio; Musante, Gabriel; Capelli, Maria C.; Pablo Berazategui, Juan; de Elizalde, Magdalena; Ignacio Fraga, Juan; Keller, Rodolfo; Ahumada, Luis; Ferreyra, Mirta; Ferreira, Vanda; Borges, Roberta; Do Vale, Marynea; Cavalcante, Silvia; Gusmao, Joama; Franco, Patricia; Jose Silva, Maria; Fabres, Jorge; Estay, Alberto; Gonzalez, Alvaro; Kattan, Javier; Quezada, Mariela; Urzua, Soledad; Campos, Lilia; Cifuentes, Lilian; Leon, Jorge; Aguilar, Roxana; Treuer, Sergio; Giaconi, Jimena; Bancalari, Aldo; Standen, Jane; Escobar, Marisol; Veas, Viviana; Sandino, Daniela; Gonzalez, Agustina; Avila, Claudia; Guzman, Carla; Toro, Claudia; Mena, Patricia; Milet, Beatriz; Pittaluga, Enrica; Pena, Veronica; Mendizabal, Rafael; Pizarro, Dagoberto; D'Apremont, Ivonne; Tapia, Jose L.; Marshall, Guillermo; Villarroel, Luis; Quezada, Mariela; Dominguez, Angelica; Lacarruba, Jose; Cespedes, Elizabeth; Mir, Ramon; Mendieta, Elvira; Genes, Larissa; Caballero, Carlos; Webb, Veronica; Rivera, Fabiola; Llontop, Margarita; Bellomo, Sicilia; Zegarra, Jaime; Chumbes, Oscar; Castaneda, Anne; Cabrera, Walter; Llanos, Raul; Mucha, Jorge; Garcia, Gustavo; Ceruti, Beatriz; Borbonet, Daniel; Gugliucci, Sandra; Lain, Ana; Martinez, Mariza; Bazan, Gabriela; Piffaretti, Susana; Cuna, Isabel; Bermudez, Patricia
    OBJECTIVE: To determine whether CS delivery and receipt of antenatal steroids (ANS) in vertex-presenting singletons with a gestational age (GA) between 24 and 30 weeks is associated with improved survival and improved severe intraventricular hemorrhage (sIVH)-free survival.
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    Modelling the vulnerability of urban settings to wildland-urban interface fires in Chile
    (2024) Aguirre, Paula; Leon, Jorge; Gonzalez-Mathiesen, Constanza; Roman, Randy; Penas, Manuela; Ogueda, Alonso
    Wildland-urban interface (WUI) regions are particularly vulnerable to wildfires due to their proximity to both nature and urban developments, posing significant risks to lives and property. To enhance our understanding of the risk profiles in WUI areas, we analysed seven fire case studies in central Chile. We developed a mixed-method approach for conducting local-scale analyses, which involved field surveys, remote-sensing through satellite and drone imagery, and GIS-based analysis of the collected data. The methodology led to the generation of a georeferenced dataset of damaged and undamaged dwellings, including 16 variables representing their physical characteristics, spatial arrangement, and the availability of fire suppression resources. A binary classification model was then used to assess the relative importance of these attributes as indicators of vulnerability. The analysis revealed that spatial arrangement factors have a greater impact on damage prediction than the structural conditions and fire preparedness of individual units. Specifically, factors such as dwelling proximity to neighbours, distance to vegetation, proximity to the border of dwelling groups, and distance from the origin of the fire substantially contribute to the prediction of fire damage. Other structural attributes associated with less affluent homes may also increase the likelihood of damage, although further data are required for confirmation. This study provides insights for the design, planning, and governance of WUI areas in Chile, aiding the development of risk mitigation strategies for both built structures and the broader territorial area.
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    The 1730 Great Metropolitan Chile Earthquake and Tsunami Commemoration: Joint Efforts to Increase the Country's Awareness
    (2020) Zamora, Natalia; Gubler, Alejandra; Orellana, Victor; Leon, Jorge; Urrutia, Alejandro; Carvajal, Matias; Cisternas, Marco; Catalan, Patricio; Winckler, Patricio; Cienfuegos, Rodrigo; Karich, Cristobal; Vogel, Stefan; Galaz, Jose; Pereira, Sebastian; Bertin, Celeste
    On 8 July 1730, a great earthquake struck metropolitan Chile, causing extensive damage 1000 km along the country and focused in Valparaiso. Due to the date of occurrence of this event, large uncertainties about the earthquake's magnitude have been discussed among the scientific community, and the earthquake and tsunami have remained unknown for most of the population. The purpose of this paper is to describe joint efforts undertaken by organizations, academia, and authorities to rescue the forgotten memory of an event that occurred almost three centuries ago and that may be repeated in the near future. In line with the Sendai Framework, we focus on one of the four priorities for action, which is to understand disaster risk, with the premise that the memory activation and raising awareness can save lives in the future. We designed outreach strategies to communicate this knowledge to the community in a participatory way. The latter involves scientific talks, earthquake simulators, tsunami projection mapping on relief scaled models (mock-up), and a public debate including the participation of academia, politicians, authorities, and the local community. The emulation of such activities and the constant work of regional and national authorities, academia, and non-governmental organizations dealing with risk mitigation encourage involving the community to build safer cities against the tsunami hazard.
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    The Role of Built Environment's Physical Urban Form in Supporting Rapid Tsunami Evacuations: Using Computer-Based Models and Real-World Data as Examination Tools
    (2019) Leon, Jorge; Mokrani, Cyril; Catalan, Patricio; Cienfuegos, Rodrigo; Femenias, Carolina
    Cities are increasingly becoming hot-spots for nature-originated disasters. While the role of the urban built environment in fostering disaster resilience has been recognized for some time, it has been difficult to translate this potential into practice. This is especially challenging in the case of rapid onset crises such as near-field tsunamis when appropriate urban forms must support the populations' ability to autonomously carry out safe and timely responses. In this respect, much of current research remains focused on large-scale elements of urban configuration (streets, squares, parks, etc.,) through which people move during an emergency. In contrast, the critical micro-scale of evacuees' experiences within the built environment is not commonly examined. This paper addresses this shortfall through a macro- and micro-scale analysis of a near-field tsunami scenario affecting the city of Vina del Mar, Chile, including a mixed-methods approach that combines computer-based models and fieldwork. The results show significant macro-scale tsunami vulnerability throughout major areas of the city, which nonetheless could be mitigated by existing nearby high ground and an urban form that allows short evacuation times. However, micro-scale outcomes show comparatively deficient spatial conditions that during an emergency might lead to dangerous outcomes including bottlenecks, falls and panic. Vertical evacuation, in turn, is confirmed as a suitable option for reducing vulnerability, but further examination of each shelter's characteristics is required.
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    Urban form planning and tsunami risk vulnerability: Analysis of 12 Chilean coastal cities
    (PALGRAVE, 2022) Vicuña Del Rio, Maria Magdalena; Leon, Jorge; Guzmán Pincheira, Simón Andrés
    Urban form has a significant impact on risk. Spatial planning instruments can optimize urban form in areas exposed to hazards. This work discusses how urban planning instruments, specifically Communal Regulatory Plans (CRPs), affect vulnerability to the risk of tsunami inundation in Chilean coastal cities. We analyze urban form and address exposure, susceptibility, and response capacity parameters. Exposure is evaluated by comparing existing and planned densities and to what extent planned risk areas coincide with inundation zones. We analyze existing critical facilities and land uses permitted by the CRP in inundation zones to evaluate susceptibility. We explore response capacity through the street network connectivity and green areas outside the inundation zone and how CRPs influence the structuring of new roads and new green spaces. We found that CRPs do not hold the sufficient capacity to incorporate and manage the tsunami inundation risk adequately. The planning scenario leads to a systematic increase in vulnerability as cities develop in exposed areas. We suggest to strengthen CRPs capacities to prevent the construction and reconstruction of areas affected by tsunamis, reinforcing the urban fabric's potential for evacuation, and to strengthen joint work between municipal urban planning and disaster risk management departments, among other recommendations.