Browsing by Author "Sepulveda, Felipe"

Now showing 1 - 6 of 6
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    A practical approach for curbing congestion and air pollution: Driving restrictions with toll and vintage exemptions
    (2021) Basso, Leonardo J.; Montero, Juan-Pablo; Sepulveda, Felipe
    Congestion and local air pollution continue to be a serious problem in many cities around the world, partly because of an increasing and ageing car fleet. Unfortunately, the use of pricing schemes for handling these externalities, such as congestion and pollution charges, still face much resistance. To cope with it, Carlos F. Daganzo advanced an ingenious hybrid scheme that supposedly leaves everybody better off: driving restrictions with toll exemptions. We extend Daganzo's idea to include vintage exemptions in an effort to also control for the pollution externality. We then test for its Pareto-improving property using Santiago as a case study. We find the latter not to hold in that low-income drivers are strictly worse off: the gain from faster car travel in days of no restriction is not enough to compensate the loss from switching to public transport in days of restriction. To make all individuals better off, the entire toll collection ought to be recycled back into the public transport system, lowering its fares and improving its quality. If so, the most ambitious hybrid restriction format -a 5-day-a-week restriction with vintage thresholds during fall and winter- reports per-year net benefits of around 1.2 billion dollars (or 0.5% of the country's GDP), 58% of which comes from lighter traffic and the remaining 42% from cleaner air.
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    Cross-examining the influence of upwelling and seaweed quality on herbivores' feeding behavior and growth
    (2024) Sepulveda, Felipe; Quijon, Pedro A.; Quintanilla-Ahumada, Diego; Vargas, Juan; Aldana, Marcela; Fernandez, Melissa; Varas, Oscar; Zapata, Javier; Pulgar, Jose; Duarte, Cristian
    At the regional scale, upwelling conditions are known to influence ecosystems and communities and their primary and secondary productivity. However, the influence of upwelling on local herbivore-algae interactions is less well understood. We address this question by cross-examining herbivores and seaweeds from sites associated with upwelling and downwelling conditions along the Humboldt Current System. Specifically, we quantified the feeding and benefits attained by the black sea urchin (Tetrapygus niger) and the black sea snail (Tegula atra) while consuming a widespread kelp species (Lessonia spicata). We hypothesized that food quality drives herbivores' preference, consumption, and growth rates, regardless of the origin or "prior" conditions of the consumers. Laboratory trials measured algal consumption rates with (preference) and without a choice, and consumer's growth rates, to assess the influence of food quality (algae from upwelling vs downwelling sites) and the site of origin of the consumers. Our results showed that algal quality was a prevailing factor for both herbivores: they chose, consumed more, and grew faster on high quality (upwelling) algae. By comparison, the origin of the consumer was only significant for sea snails: those coming from an upwelling site, consumed significantly more and grew faster than those from downwelling. The bulk of our results provided strong support to our hypothesis and suggest that the high nutritional quality of algae associated with upwelling centers has a strong influence on consumers' preferences, consumption, and performance (growth). The fact that origin was found to be relevant for one of the herbivores suggests that the conditions in which species grow may dictate some of their efficiency as consumers.
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    High Performance of Mn2O3 Electrodes for Hydrogen Evolution Using Natural Bischofite Salt from Atacama Desert: A Novel Application for Solar Saline Water Splitting
    (2024) Galleguillos-Madrid, Felipe M.; Salazar-Avalos, Sebastian; Fuentealba, Edward; Leiva-Guajardo, Susana; Caceres, Luis; Portillo, Carlos; Sepulveda, Felipe; Brito, Ivan; Cobos-Murcia, Jose Angel; Rojas-Moreno, Omar F.; Jimenez-Arevalo, Victor; Schott, Eduardo; Soliz, Alvaro
    Solar saline water splitting is a promising approach to sustainable hydrogen production, harnessing abundant solar energy and the availability of brine resources, especially in the Atacama Desert. Bischofite salt (MgCl26H2O) has garnered significant attention due to its wide range of industrial applications. Efficient hydrogen production in arid or hyper arid locations using bischofite solutions is a novel and revolutionary idea. This work studied the electrochemical performance of Mn2O3 electrodes using a superposition model based on mixed potential theory and evaluated the superficial performance of this electrode in contact with a 0.5 M bischofite salt solution focusing on the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) that occur during saline water splitting. The application of the non-linear superposition model provides valuable electrochemical kinetic parameters that complement the understanding of Mn2O3, this being one of the novelties of this work.
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    Network pharmacology reveals multitarget mechanism of action of drugs to be repurposed for COVID-19
    (2022) Alegria-Arcos, Melissa; Barbosa, Tabata; Sepulveda, Felipe; Combariza, German; Gonzalez, Janneth; Gil, Carmen; Martinez, Ana; Ramirez, David
    The coronavirus disease 2019 pandemic accelerated drug/vaccine development processes, integrating scientists all over the globe to create therapeutic alternatives against this virus. In this work, we have collected information regarding proteins from SARS-CoV-2 and humans and how these proteins interact. We have also collected information from public databases on protein-drug interactions. We represent this data as networks that allow us to gain insights into protein-protein interactions between both organisms. With the collected data, we have obtained statistical metrics of the networks. This data analysis has allowed us to find relevant information on which proteins and drugs are the most relevant from the network pharmacology perspective. This method not only allows us to focus on viral proteins as the main targets for COVID-19 but also reveals that some human proteins could be also important in drug repurposing campaigns. As a result of the analysis of the SARS-CoV-2-human interactome, we have identified some old drugs, such as disulfiram, auranofin, gefitinib, suloctidil, and bromhexine as potential therapies for the treatment of COVID-19 deciphering their potential complex mechanism of action.
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    On the geography of vintage-specific restrictions
    (2023) Fardella, Carlos; Barahona, Nano; Montero, Juan-Pablo; Sepulveda, Felipe
    Persistent air-pollution problems have led authorities in many cities around the world to impose limits on car use by means of vintage-specific restrictions or low-emission zones. Any vintage restriction must establish not only the cars that face a restriction but also its geographic area of application. As a result of the restriction, a fraction of restricted cars are exported outside the restricted area. Because restricted cars become cheaper, emissions in the restricted area could increase if exported cars remain too close to it. The extent to which such emissions leakage can occur crucially depends on transaction costs in the car market. We study this possibility with a model of the car market that allows for transaction costs and data from Santiago's 2017 vintage restriction. We fail to find emissions leakage, at least severe enough to undo the 2017 policy effects. Interestingly, transaction costs are shown to have a non-monotonic impact on emissions, and hence, on welfare.
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    Prophages carrying Zot toxins on different Vibrio genomes: A comprehensive assessment using multilayer networks
    (2024) Soto, Esteban F.; Alegria, Melissa; Sepulveda, Felipe; Garcia, Katherine; Higuera, Gaston; Castillo, Daniel; Fonturbel, Francisco E.; Bastias, Roberto
    Vibrios, a group of bacteria that are among the most abundant in marine environments, include several species such as Vibrio cholerae and Vibrio parahaemolyticus, which can be pathogenic to humans. Some species of Vibrio contain prophages within their genomes. These prophages can carry genes that code for toxins, such as the zonula occludens toxin (Zot), which contribute to bacterial virulence. Understanding the association between different Vibrio species, prophages and Zot genes can provide insights into their ecological interactions. In this study, we evaluated 4619 Vibrio genomes from 127 species to detect the presence of prophages carrying the Zot toxin. We found 2030 potential prophages with zot-like genes in 43 Vibrio species, showing a non-random association within a primarily modular interaction network. Some prophages, such as CTX or Vf33, were associated with specific species. In contrast, prophages phiVCY and VfO3K6 were found in 28 and 20 Vibrio species, respectively. We also identified six clusters of Zot-like sequences in prophages, with the ZOT2 cluster being the most frequent, present in 34 Vibrio species. This analysis helps to understand the distribution patterns of zot-containing prophages across Vibrio genomes and the potential routes of Zot-like toxin dissemination.