COVID-19 pandemic: a mobility-dependent SEIR model with undetected cases in Italy, Europe, and US.

OBJECTIVES: to describe the first wave of the COVID-19 pandemic with a focus on undetected cases and to evaluate different post-lockdown scenarios. DESIGN: the study introduces a SEIR compartmental model, taking into account the region-specific fraction of undetected cases, the effects of mobility restrictions, and the personal protective measures adopted, such as wearing a mask and washing hands frequently. SETTING AND PARTICIPANTS: the model is experimentally validated with data of all the Italian regions, some European countries, and the US. MAIN OUTCOME MEASURES: the accuracy of the model results is measured through the mean absolute percentage error (MAPE) and Lewis criteria; fitting parameters are in good agreement with previous literature. RESULTS: the epidemic curves for different countries and the amount of undetected and asymptomatic cases are estimated, which are likely to represent the main source of infections in the near future. The model is applied to the Hubei case study, which is the first place to relax mobility restrictions. Results show different possible scenarios. Mobility and the adoption of personal protective measures greatly influence the dynamics of the infection, determining either a huge and rapid secondary epidemic peak or a more delayed and manageable one. CONCLUSIONS: mathematical models can provide useful insights for healthcare decision makers to determine the best strategy in case of future outbreaks.

Stackelberg evolutionary game theory: how to manage evolving systems.

Stackelberg evolutionary game (SEG) theory combines classical and evolutionary game theory to frame interactions between a rational leader and evolving followers. In some of these interactions, the leader wants to preserve the evolving system (e.g. fisheries management), while in others, they try to drive the system to extinction (e.g. pest control). Often the worst strategy for the leader is to adopt a constant aggressive strategy (e.g. overfishing in fisheries management or maximum tolerable dose in cancer treatment). Taking into account the ecological dynamics typically leads to better outcomes for the leader and corresponds to the Nash equilibria in game-theoretic terms. However, the leader's most profitable strategy is to anticipate and steer the eco-evolutionary dynamics, leading to the Stackelberg equilibrium of the game. We show how our results have the potential to help in fields where humans try to bring an evolutionary system into the desired outcome, such as, among others, fisheries management, pest management and cancer treatment. Finally, we discuss limitations and opportunities for applying SEGs to improve the management of evolving biological systems. This article is part of the theme issue 'Half a century of evolutionary games: a synthesis of theory, application and future directions'.

The Contribution of Evolutionary Game Theory to Understanding and Treating Cancer.

Evolutionary game theory mathematically conceptualizes and analyzes biological interactions where one's fitness not only depends on one's own traits, but also on the traits of others. Typically, the individuals are not overtly rational and do not select, but rather inherit their traits. Cancer can be framed as such an evolutionary game, as it is composed of cells of heterogeneous types undergoing frequency-dependent selection. In this article, we first summarize existing works where evolutionary game theory has been employed in modeling cancer and improving its treatment. Some of these game-theoretic models suggest how one could anticipate and steer cancer's eco-evolutionary dynamics into states more desirable for the patient via evolutionary therapies. Such therapies offer great promise for increasing patient survival and decreasing drug toxicity, as demonstrated by some recent studies and clinical trials. We discuss clinical relevance of the existing game-theoretic models of cancer and its treatment, and opportunities for future applications. Moreover, we discuss the developments in cancer biology that are needed to better utilize the full potential of game-theoretic models. Ultimately, we demonstrate that viewing tumors with evolutionary game theory has medically useful implications that can inform and create a lockstep between empirical findings and mathematical modeling. We suggest that cancer progression is an evolutionary competition between different cell types and therefore needs to be viewed as an evolutionary game.

Fisheries management as a Stackelberg Evolutionary Game: Finding an evolutionarily enlightened strategy.

Fish populations subject to heavy exploitation are expected to evolve over time smaller average body sizes. We introduce Stackelberg evolutionary game theory to show how fisheries management should be adjusted to mitigate the potential negative effects of such evolutionary changes. We present the game of a fisheries manager versus a fish population, where the former adjusts the harvesting rate and the net size to maximize profit, while the latter responds by evolving the size at maturation to maximize the fitness. We analyze three strategies: i) ecologically enlightened (leading to a Nash equilibrium in game-theoretic terms); ii) evolutionarily enlightened (leading to a Stackelberg equilibrium) and iii) domestication (leading to team optimum) and the corresponding outcomes for both the fisheries manager and the fish. Domestication results in the largest size for the fish and the highest profit for the manager. With the Nash approach the manager tends to adopt a high harvesting rate and a small net size that eventually leads to smaller fish. With the Stackelberg approach the manager selects a bigger net size and scales back the harvesting rate, which lead to a bigger fish size and a higher profit. Overall, our results encourage managers to take the fish evolutionary dynamics into account. Moreover, we advocate for the use of Stackelberg evolutionary game theory as a tool for providing insights into the eco-evolutionary consequences of exploiting evolving resources.

Aplicación de indicadores ambientales para la planificación del uso del suelo en una zona costera de Buenos Aires, Argentina / Application of environmental indicators for land use planning in a coastal area of Buenos Aires, Argentina

RESUMEN El objetivo de este trabajo fue aplicar indicadores e índices ambientales en una zona costera localizada en el noreste de la provincia de Buenos Aires (Argentina). El área de estudio se ubica en el sector de la planicie costera del Río de la Plata, correspondiente al partido de Ensenada. La misma es un área con alto valor para la biodiversidad regional y brinda numerosos servicios ecosistémicos. Además, está expuesta de manera recurrente a inundaciones y anegamientos, los cuales, determinan fuertes condicionantes para el uso del suelo. Se identificaron y seleccionaron indicadores que aportan información sobre características estructurales y funcionales del medio natural, respecto de su fragilidad frente a intervenciones, a partir de los criterios: vulnerabilidad natural, valor patrimonial y condicionamientos naturales frente a intervenciones antrópicas; estos indicadores fueron integrados para obtener un Índice de Fragilidad Natural Territorial (IFNT). Se generaron mapas temáticos de índices parciales y un mapa final correspondiente al IFNT, mediante el uso de Sistemas de Información Geográfica (SIG). Los resultados obtenidos establecen que el 15,1 % de la superficie del partido presenta una fragilidad natural entre muy alta (2,1 %) y alta (13 %) y un 20,2 %, con valores medios, asociados a ambientes de escasa pendiente del centro, W y E-SE del territorio, así como al sector más próximo a la ribera rioplatense, donde se asientan áreas urbanas. Se observó tendencia de crecimiento urbano avanzando sobre sectores identificados con fragilidad entre muy alta y media. Este índice se considera una herramienta útil para la planificación territorial sostenible.

ABSTRACT The objective of this paper was to apply environmental indicators and indexes in a coastal area located in the northeastern province of Buenos Aires (Argentina). The study area is located in the sector of the coastal plain of the Río de la Plata corresponding to the Ensenada district. It is an area of high regional biodiversity value and provides numerous ecosystem services. In addition, it is exposed to frequent flood events and waterlogged soils, which determines strong conditioning factors for land use. In this paper, the application of environmental indicators and indexes developed ad hoc is presented in order to assist in the sustainable land use planning of the territory. Indicators were identified and selected to provide information on structural and functional characteristics of the natural environment regarding its fragility in front of anthropic interventions. These indicators were made following these selection criteria: natural vulnerability, patrimonial value and natural conditioning to anthropic interventions. These indicators were integrated to obtain a Natural Territorial Fragility Index (NTFI). Thematic maps of intermediate indexes were generated, as well as a final map corresponding to the NTFI, integrated in a GIS. The results obtained from the NTFI calculation establish that 15,1 % of the area of the district presents a natural fragility with values very high (2,1 %) and high (13 %) and 20,2 % medium value. In the center, W and E-SE of the territory, as well as in the sector closest to the rioplatense riverbank, the NTFI presents very high to medium values mainly associated with low slope environments. Urban areas are developed in this location. There is an urban growth trend advancing on sectors identified with very high to moderate fragility. This index is considered a useful tool for sustainable territorial planning.

Pyrene degradation by yeasts and filamentous fungi.

The saprotrophic soil fungi Fusarium solani (Mart.) Sacc., Cylindrocarpon didymum (Hartig) Wollenw, Penicillium variabile Sopp. and the yeasts Rhodotorula glutinis (Fresenius) Harrison and Rhodotorula minuta (Saito) Harrison were cultured in mineral medium with pyrene. The remaining pyrene concentrations were periodically determined during 20 incubation days, using HPLC. To assess the metabolism of pyrene degradation we added 0.1 microCi of [4,5,9,10] 14C-pyrene to each fungi culture and measured the radioactivity in the volatile organic substances, extractable, aqueous phase, biomass and 14CO2 fractions. The assays demonstrated that F. solani and R. glutinis metabolized pyrene as a sole source of carbon. Differences in their activities at the beginning of the cultures disappeared by the end of the experiment, when 32 and 37% of the original pyrene concentration was detected, for the soil fungi and yeasts, respectively. Among the filamentous fungi, F. solani was highly active and oxidized pyrene; moreover, small but significant degradation rates were observed in C. didymum and P. variahile cultures. An increase in the 14CO2 evolution was observed at the 17th day with cosubstrate. R. glutinis and R. minuta cultures showed similar ability to biotransform pyrene, and that 35% of the initial concentration was consumed at the end of the assay. The same results were obtained in the experiments with or without glucose as cosubstrate.