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- ItemElectrotrophic perchlorate reduction by a psychrotolerant acidophile isolated from an acid rock drainage in Antarctica(Elsevier Science SA, 2023) Torres-Rojas, Felipe; Hernández, Pedro; Vargas Barrios, Tomás Ignacio; Nancucheo, IvánA new extremophilic isolate (USS-CCA7) was obtained from an acidic environment (pH -3.2) in Antarctica phylogenetically related to Acidithiobacillus ferrivorans; its electrotrophic capacities were evaluated in a three-electrode electrochemical cell. Cyclic voltammetry showed cathodic peaks of-428 mV,-536 mV, and-634 mV (vs. Ag/AgCl; pH = 1.7; 3 M KCl) for nitrate, oxygen, and perchlorate, respectively. The catalytic role of this microorganism was also observed by a decrease in the charge transfer resistance registered via electrochemical impedance spectroscopy. Five-day chronoamperometry of culture at pH = 1.7, USS-CCA7 showed a perchlorate removal rate of 19.106 +/- 1.689 mgL-1 day-1 and a cathodic efficiency of 112 +/- 5.2 %. Growth on electrodes was observed by epifluorescence and scanning electron microscopy. Interestingly, the results showed that toward higher pH, the cathodic peak of perchlorate is reduced in the voltammetric profiles. This study highlights the use of this psychrotolerant acidophile for the bioremediation of harsh perchlorate-pressured terrestrial under acidic conditions.
- ItemImprovement of the thermal performance of hollow clay bricks for structural masonry walls(2024) Vera Araya, Sergio Eduardo; Figueroa Cofré, Camilo Iván; Chubretovic Arnaiz, Soledad; Remesar Lera, José Carlos; Vargas, Felipe; CEDEUS (Chile)Although structural masonry walls are widely used in construction, achieving lower U-value is crucial to minimize energy losses and greenhouse gas emissions. The effect on the U-value of hollow clay masonry walls is evaluated by modifying the clay and mortar thermal conductivities, as well as the brick grid and thickness. Heat transfer through bricks and walls was modeled using a 3D-finite element method while model validation was based on experimental tests. Smaller rectangular cavities reduce the U-value to 0.761 W/m2K; increasing the brick thickness reduces the U-value to 0.563 W/m2K. Moreover, reducing the clay thermal conductivity showed negligible reductions in the wall U-value.
- ItemDynamics of metals in street dust after a mudslide: Case of mining city in Chile(2019) Vega Contreras, Alejandra Soledad; Arce, Guillermo; Carkovic Aguilera, Athena B.; Moya, Pablo; Coquery, Marina; Pastén González, Pablo Arturo; CEDEUS (Chile)
- ItemThe role of socio-territorial conditions and distance to infrastructure for promoting recycling in Latin American cities: The case of Santiago de Chile(Elsevier Ltd, 2023) Valenzuela Levi, Nicolás Darío; Flores Castillo, Mónica AndreaConvenient distances and higher density of drop-off points are expected to increase the probability of people participating in waste separation. However, although several analyses search for optimal distances between users and drop-off points, they tend to concentrate on European case studies. Few studies have analysed the actuallyexisting experiences regarding these factors in cities from the Global South. In this context, the authors provide an analysis on Santiago, the capital of Chile. A survey (N = 387) is generated to represent five neighbourhood clusters, and a logit binary outcome model is used to analyse the data. The research also considers territorial conditions based on the specific characteristics of the Latin American cities, particularly socioeconomic variables and location (i.e. centre versus periphery). The findings point towards a prominent role of educational levels, and an inverted U relationship between proximity to drop off points and the probability of recycling. Additionally, in the case of metals, results indicate that probability of recycling is higher both in the areas that concentrate the poor and in those that concentrate the rich. Such result is most likely associated to a contrasting relationship between recycling and socioeconomic variables: one linked to the need of generating income, and the other to privilege (i.e. conspicuous consumption and domestic workers).
- ItemMachine learning for policing: a case study on arrests in Chile(2020) Wout, Elwin van't; Pieringer Baeza, Christian Philip; Torres Irribarra, David; Asahi Kodama, Kenzo Javier; Larroulet Philippi, Pilar; CEDEUS (Chile)Police agencies expend considerable effort to anticipate future incidences of criminal behaviour. Since a large proportion of crimes are committed by a small group of individuals, preventive measures are often targeted on prolific offenders. There is a long-standing expectation that new technologies can improve the accurate identification of crime patterns. Here, we explore big data technology and design a machine learning algorithm for forecasting repeated arrests. The forecasts are based on administrative data provided by the national Chilean police agencies, including a history of arrests in Santiago de Chile and personal metadata such as gender and age. Excellent algorithmic performance was achieved with various supervised machine learning techniques. Still, there are many challenges regarding the design of the mathematical model, and its eventual incorporation into predictive policing will depend upon better insights into the effectiveness and ethics of preemptive strategies.