Journal Pre-proof J o u r n a l P r e -p r o o f Lockdown, one, two, none, or smart. Modeling containing COVID-19 infection. A conceptual model. Abstract A mathematical model has been created with the Systems Dynamics methodology. It is based on a SIR model, with the addition of auxiliary and state variables that represent hospital capacity, contacts, contacts with infected, deaths, giving, as a result, a model of four stock variables. Similarly, using piecewise functions, it was possible to model the "quarantines" or lockdowns, and the effectiveness of reduction in the contacts, Results show the decrease in infected people due to the quarantines. The model was simulated for a population of 100,000. The simulations show trends of infections that could occur in three different scenarios: A) one extended lockdown (60 days), B) two medium lockdowns of 30 days, with a 30-day smart lockdown space, and C) an initial 40-day lockdown and then a 30-day smart lockdown. All the lockdowns start on day 25 after the first reported infection. The model presents a compact structure of broad understanding and successful capture of a COVID-19 outbreak and therefore provides an overview to improve knowledge of outbreak trends and quarantine effectiveness in reducing infection.Systems Dynamics models seek to guide the understanding of trends behavior, under policies or strategies that are implemented, knowing their structure and the relationships that exist, are not predictive models. ConclusionsThrough modeling with Systems Dynamics, successful representation of the coronavirus outbreak was created for a population of 100,000 inhabitants. The mathematical model has a general structure like that of the SIRD model presented by (Fanelli and Piazza, 2020). However, due to the flexibility of the methodology, the effects of implemented quarantines have been modeled, whether they are long quarantines, double quarantines, smart, or combined quarantines. Journal Pre-proof

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This paper presents a model and simulations, which was built with a System Dynamics methodology applied to waste management in the bioethanol supply chain in Colombia. The stages of the supply chain used were cane planting, production and the distribution process. The residues taken into account were bagasse and vinasse. Moreover, four simulation scenarios were performed in which the values of variables modified management strategies. The installed bioethanol production capacity was increased to observe the evolution of increased waste generation evaluated. The initial conditions for the simulation were modified to represent a production of about 2,500,000 liters / day. This leads to an increased generation of vinasse of over 400 million liters on average in a month and around more than 1 million tones of bagasse. The results are used to estimate the impact of management strategies on the amount of waste generated in the production of bioethanol.

RESUMENLos problemas ambientales que afectan a las cuencas hidrográficas en Colombia tienen múltiples causas, una de ellas es la ausencia de una cultura ambiental en las comunidades que viven o frecuentan zonas aledañas a las corrientes hídricas. El principal objetivo de este trabajo era recopilar la percepción local sobre el estado ambiental de la cuenca baja del río Manzanares, ubicada en el departamento del Magdalena e incentivar a los pobladores a reflexionar sobre su papel frente a la solución de las principales problemáticas. Para lograr este objetivo se utilizaron diferentes herramientas metodológicas, 1) Encuesta dirigida a los pobladores de la zona, 2) talleres participativos con estudiantes, 3) desarrollo de recorridos de reconocimiento ambiental y territorial. A través de estos últimos se recopiló la percepción de los participantes sobre componentes ambientales básicos: agua, aire, suelo, flora, fauna y saneamiento básico. Se realizaron dos recorridos con grupos diferentes, teniendo un total 50 estudiantes del grado décimo de un colegio ubicado en la zona de estudio y algunos estudiantes universitarios. A través de este estudio se encuentra que la principal problemática percibida por la comunidad de la cuenca baja del río Manzanares en Santa Marta, es la contaminación del agua por el aporte de aguas residuales y la disposición no controlada de residuos sólidos; esta última causa, ligada a la falta de una cultura ambiental no solo en los residentes de la ciudad sino también en sus visitantes. PALABRAS CLAVEPercepción, recorrido ambiental, cuenca hidrográfica.

This paper presents a model for the evaluation of strategies in the management of Waste Electrical and Electronic Equipment (WEEE). Waste represents a risk to public health and the environment, the dangerous type compounds that constitute them and the increase of their generation. In Colombia, there is a law of 1672 guidelines for the adoption of a policy that improves the management of WEEE. This Law proposes public management objectives, of which in this article three of them were evaluated (Reduction in generation, incentive to use, promote integrated participation). For this evaluation, a model was built using the Dynamics of Systems methodology, which allowed the establishment of the socio-environmental system structure for the generation and management of WEEE. Likewise, the evaluation scenarios were defined, the first is the initial or natural state that corresponds to the system without any strategy and the second is the system with the implementation of the strategies, which were divided into two groups. One is Economic Circular Strategies, Environmental Education and Job Promotion, and the other group contains the producer's extended liability strategies, citizenship incentives and the collection rate. Model simulations and scenario comparisons showed that the first group of strategies decreased in the generation rate of WEEE. Likewise, they allowed a second group of strategies on disposition rate. Likewise, the proposed model for the management of Waste Electrical and Electronic Equipment is useful for the evaluation of waste management strategies in different scenarios.Keywords: waste; modeling; system dynamics; public management.Evaluación de estrategias para la gestión integral de residuos de aparatos eléctricos y electrónicos ResumenEste artículo presenta un modelo para la evaluación de estrategias en la gestión de Residuos de Aparatos Eléctricos y Electrónicos (RAEE). Estos residuos representan un riesgo para la salud pública y para el medio ambiente, por los compuestos de tipo peligroso que los constituyen y el aumento de su generación. En Colombia existe desde 2013 la ley 1672 lineamientos para la adopción de una política que mejore la gestión de los RAEE. Esta Ley propone objetivos gestión pública, de los cuales en este artículo se evaluaron tres de ellos (Reducción en la generación, incentivo al aprovechamiento, promover la participación integrada). Para esta evaluación, se construyó un modelo utilizando la metodología de Dinámica de Sistemas, la cual permitió establecer la estructura del sistema socio-ambiental de generación y manejo de los RAEE. Así mismo, fueron definidos dos escenarios de evaluación, el primero es el estado inicial o natural que corresponde al sistema sin ninguna estrategia y el segundo es el sistema con la implementación de las estrategias, las cuales se dividieron en dos grupos. Uno es Estrategias de economía circular, educación ambiental y fomento de empleo, y el otro grupo contiene las estrategias de responsabilidad extendida del productor, estímulos de la ciu...