3,062 research outputs found

    Epidemic Spreading in Random Rectangular Networks

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    The use of network theory to model disease propagation on populations introduces important elements of reality to the classical epidemiological models. The use of random geometric graphs (RGG) is one of such network models that allows for the consideration of spatial properties on disease propagation. In certain real-world scenarios -like in the analysis of a disease propagating through plants- the shape of the plots and fields where the host of the disease is located may play a fundamental role on the propagation dynamics. Here we consider a generalization of the RGG to account for the variation of the shape of the plots/fields where the hosts of a disease are allocated. We consider a disease propagation taking place on the nodes of a random rectangular graph (RRG) and we consider a lower bound for the epidemic threshold of a Susceptible-Infected-Susceptible (SIS) or Susceptible-Infected-Recovered (SIR) model on these networks. Using extensive numerical simulations and based on our analytical results we conclude that (ceteris paribus) the elongation of the plot/field in which the nodes are distributed makes the network more resilient to the propagation of a disease due to the fact that the epidemic threshold increases with the elongation of the rectangle. These results agree with accumulated empirical evidence and simulation results about the propagation of diseases on plants in plots/fields of the same area and different shapes.Comment: Version 4, 13 pages, 6 figures, 44 ref

    Hybridization of Renewable Energy Systems with Battery Storage : A Techno-economic Optimization

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    The current energy landscape is one where renewables are finally in the right deployment stage to achieve the decarbonization of our energy systems and to limit climate change as per the current agreements. This is thanks to the learning rates of these technologies as well as policies in place. However, many projects now face regulation and permitting bot- tlenecks of several years plus uncertainties regarding wholesale market prices and possi- ble curtailment. Hybrid Renewable Energy Systems (HRES) are seen as an alternative to these issues, as they can take advantage of regulations in place to bypass interconnection queues and can capture higher prices in the markets. Throughout this work, a user-friendly optimization model is developed in collaboration with ODENRA, a Spanish project developer, to evaluate the profitability of hybridizing existing renewable power plants with battery energy storage systems (BESS), investigat- ing the opportunity for energy arbitrage to maximize revenues while taking into account battery degradation. The model is implemented using Python and is then used in a case study for a representative 40MWp Solar PV plant in Spain, where it is found that hy- bridization is not profitable with the existing costs and revenue projections from arbitrage, so participation in other markets and new revenue mechanisms are needed to improve the business case of these projects and match them to the benefits provided to the system and consumersActualmente el sector energético se encuentra finalmente en la trayectoria correcta para decarbonizar los sistemas energéticos y limitar el cambio climático gracias al auge de las energías renovables. Se da este caso gracias a las curvas de aprendizaje de estas tec- nologías, al igual que las políticas actuales. Sin embargo, varios proyectos se han encon- trado con nuevos retos y cuellos de botella en lo que concierne a regulación y permisos de acceso a la red, al igual que riesgos por la volatilidad de precios en los mercados de electricidad y por congestiones en la red. Los sistemas híbridos de energías renovables son considerados como una alternativa para evitar los tiempos de espera en la obtención de permisos y para poder capturar mayores precios en los mercados. A lo largo de esta tésis, un modelo de optimización amigable para el usuario es desar- rollado en colaboración con ODENRA, empresa que desarrolla proyectos energéticos en España, con el objetivo de evaluar la rentabilidad de hibridar plantas de energía renovable con sistemas de almacenamiento de baterías, evaluando la oportunidad para realizar arbi- traje de energía, maximizando los ingresos y considerando la degradación de las baterías. El modelo es implementado utilizando Python y es puesto a prueba con un caso de es- tudio de una planta solar fotovoltaica de 40MWp en España, donde el resultado no es favorable, al no ser rentable la hibridación considerando solo ingresos por arbitraje y con los costos actuales, por lo que son necesarios mecanismos de ingresos adicionales como la participación en otros mercados, para mejorar el caso de negocio de tal manera que sea una inversión atractiva para los inversores y no solo para el sistema y los consumidoresActualment el sector energètic es troba finalment en la trajectòria correcta para descar- bonitzar els sistemes energètics i limitar el canvi climàtic gràcies a l’auge de les energies renovables. Es dona aquest cas gràcies a les corbes d’aprenentatge d’aquestes tecnologies, igual que les polítiques actuals. No obstant això, diversos projectes s’han trobat amb nous reptes i colls d’ampolla en el que concerneix regulació i permisos d’accés a la xarxa, igual que riscos per la volatilitat de preus en els mercats d’electricitat i per congestions en la xarxa. Els sistemes híbrids d’energies renovables són considerats com una alternativa per a evitar els temps d’espera en l’obtenció de permisos i per a poder capturar majors preus en els mercats. Al llarg d’aquesta tesi, un model d’optimització amigable per a l’usuari és desenvolu- pat en col·laboració amb ODENRA, empresa que desenvolupa projectes energètics a Es- panya, amb l’objectiu d’avaluar la rendibilitat d’hibridar plantes d’energia renovable amb sistemes d’emmagatzematge de bateries, avaluant l’oportunitat per a realitzar arbitratge d’energia, maximitzant els ingressos i considerant la degradació de les bateries. El model és implementat utilitzant Python i és posat a prova amb un cas d’estudi d’una planta solar fotovoltaica de 40MWp a Espanya, on el resultat no és favorable, al no ser rendible la hibri- dació considerant sol ingressos per arbitratge i amb els costos actuals, per la qual cosa són necessaris mecanismes d’ingressos addicionals com la participació en altres mercats, per a millorar el cas de negoci de tal manera que sigui una inversió atractiva per als inversors i no sols per al sistema i els consumidor

    Los falsos positivos en el marco del discurso de la Seguridad Democrática

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    El interés del presente Estudio de Caso es observar la influencia del discurso de la Seguridad Democrática en el aumento de los falsos positivos durante los dos periodos presidenciales de Álvaro Uribe Vélez. El trabajo tiene como idea central que la seguridad propuesta por este actor, tiene especial interés en el aspecto económico con el fin de plantear el desarrollo desde la inversión extranjera. Para lograr esto, se da la lógica del todo vale con el fin de mejorar las condiciones de seguridad para aumentar las cifras de guerrilleros dados de baja en combate, se presentan los falsos positivos. Para demostrar esto se realizará un análisis del discurso de las categorías de ideología y contexto de la Seguridad Democrática en sus manifestaciones y materializaciones.The interest of this Study Case, is watch the influence of the discourse of “Seguridad Democrática” in the raise of the “Falsos Positivos” during the two periods as a president of Álvaro Uribe. This work have as the central idea, that the security propose for this actor, got one special interest in the economics with the purpose of pose the development since the foreign investment. For got this the logic of everything count with the end of improve the condition of security, for raise the number of the members of the FARC and ELN down in combat, present the “Falsos Positivos”. For prove this it will be performed one analysis of the discourse of the categories of ideology and context of the “Seguridad Democrática” on their manifestations and materialization

    Functional biogeography: testing new approaches based on gross primary production

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    Functional biogeography focuses on understanding the causes and consequences of the spatial distribution of functional traits. One of the functions that plants fulfill in ecosystems is to regulate the exchange of energy and matter through photosynthesis (i.e., Gross Primary Production, GPP). In this direction, previous studies define the maximum photosynthetic capacity (GPPmax) as an Ecosystem Functional Property (EFP). It is expected that EFPs will help to better understand how ecosystems are affected by climate change and global warming. In this dissertation, I present how to understand an ecosystem function such as GPP and an EFP as GPPmax through three main axes: Magnitude, Time and Space. Specifically, in the first axis, I focus on understanding how environmental variables limit GPPmax at a global scale. In the second axis, time, I evaluate how climatic variables affect the timing (i.e. Day of the year, DOY) when GPPmax is reached (DOYGPPmax). Finally, on the last axis, I explore how new satellite missions can help improve GPP prediction. In the first axis, my approach using an optimal ecosystem process as GPPmax and its limiting factors allow us to generate a new functional map that relate optimum ecosystem processes with climate information. This new map can be used as input for future global-scale modeling studies. On the second axis, Time, I find that for most of the ecosystems across the globe, an increase in short-wave incoming radiation, temperature, and vapor pressure deficit will produce an earlier DOYGPPmax (when compared with the mean DOYGPPmax) during the growing season. In the last axis, Space, I find that red-edge vegetation indices (estimated from Sentinel-2 images) improve the performance of the prediction of GPP. The exploration of the axes proposed in this dissertation contribute to frame our understanding of vegetation functional biogeography, by combining concepts from biometeorology, ecosystem physio-phenology, and satellite observations

    Eficiencia de la inversión y desarrollo humano del proyecto de Desarrollo del proceso agroindustrial de la fruta tropical Maracuyás (Pasiflora edulis) realizado por el ministerio de economía familiar cooperativa, comunitaria y asociativa en los Municipios San Ramón, del departamento de Matagalpa; durante el segundo semestre del 2013

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    El presente trabajo está enfocado en la temática eficiencia de la inversión e impacto en el desarrollo humano del proyecto´´ proceso agroindustrial de las frutas tropicales maracuyá realizado por el Ministerio de Economía familiar comunitaria cooperativa y asociativa (MEFCCA) durante el segundo semestre del 2013 en el departamento de Matagalpa. En el trabajo investigativo se realizó un análisis a los productores beneficiados por el proyecto de proceso agroindustrial de maracuyás, además valorar las condiciones de desarrollo humano que se está ejecutando en algunas comunidades en los municipios de San Ramón, Sébaco y Tuma La Dalia; en las comunidades san Ramón, Guadalupe, Samulali, Yucul, Pueblo Viejo, Apatite, Departamento de Matagalpa,. En la investigación se analizaron elementos que se manifiestan e influyen de forma directa sobre la eficiencia de la inversión y desarrollo humano, por medio de la ejecución del Programa PROCAVAL, En la que se utilizaron técnicas dirigidas a los beneficiados del proyecto; socios activos de la Cooperativa COMANOR R.L, encuestas, entrevista, grupos focales y guía de observación. El proyecto se encuentra en fases ejecución de acuerdo a los objetivos propuesto del proyecto PROCACAL. Uno de los objetivo del proyecto es ayudar al fortalecimiento organizacional y seguimiento del proceso de agregación de valor y al mismo tiempo lograr la inserción exitosa al mercado nacional e internacional. El propósito del MEFCCA -PROCAVAL es que las familias en condiciones de pobreza del área rural, mejoren sus capacidades organizacionales como empresas, oportunidades de empleo, su capacidad de generar y diversificar los ingresos, a través de la inserción en cadenas de valor y mercados competitivo

    Dominance Measuring Approach using Stochastic Weights

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    In this paper we propose an approach to obtain a ranking of alternatives in multicriteria decision-making problems when there is imprecision concerning the alternative performances, component utility functions and weights. We assume decision maker's preferences are represented by an additive multi-attribute utility function, in which weights are modeled by independent normal variables, the performance in each attribute for each alternative is an interval value and classes of utility functions are available for each attribute. The approach we propose is based on dominance measures, which are computed in a similar way that when the imprecision concerning weights is modeled by uniform distributions or by an ordinal relation. In this paper we will show how the approach can be applied when the imprecision concerning weights are represented by normal distributions. Extensions to other distributions, such as truncated normal or beta, can be feasible using Monte Carlo simulation techniques

    Ranking Alternatives on the Basis of a Dominance Intensity Measure

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    The additive multi-attribute utility model is widely used within MultiAttribute Utility Theory (MAUT), demanding all the information describing the decision-making situation. However, these information requirements can obviously be far too strict in many practical situations. Consequently, incomplete information about input parameters has been incorporated into the decisionmaking process. We propose an approach based on a dominance intensity measure to deal with such situations. The approach is based on the dominance values between pairs of alternatives that can be computed by linear programming. These dominance values are transformed into dominance intensities from which a dominance intensity measure is derived. It is used to analyze the robustness of a ranking of technologies for the disposition of surplus weapons-grade plutonium by the Department of Energy in the USA, and compared with other dominance measuring methods

    Cannabinoids, Chemical Senses, and Regulation of Feeding Behavior

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    The herb Cannabis sativa has been traditionally used in many cultures and all over the world for thousands of years as medicine and recreation. However, because it was brought to the Western world in the late 19th century, its use has been a source of controversy with respect to its physiological effects as well as the generation of specific behaviors. In this regard, the CB1 receptor represents the most relevant target molecule of cannabinoid components on nervous system and whole-body energy homeostasis. Thus, the promotion of CB1 signaling can increase appetite and stimulate feeding, whereas blockade of CB1 suppresses hunger and induces hypophagia. Taste and flavor are sensory experiences involving the oral perception of food-derived chemicals and drive a primal sense of acceptable or unacceptable for what is sampled. Therefore, research within the last decades focused on deciphering the effect of cannabinoids on the chemical senses involved in food perception and consequently in the pattern of feeding. In this review, we summarize the data on the effect of cannabinoids on chemical senses and their influences on food intake control and feeding behavior

    Validación herramienta observacional para el análisis de rachas de lanzamiento en baloncesto

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    El objetivo de esta investigación fue diseñar y validar una herramienta de observación ad-hoc para el análisis de las rachas de lanzamiento en el baloncesto profesional. Para dicho proceso de validación se han desarrollado 5 fases: Fase 1) Identificación, selección y categorización de posibles variables a incluir en la herramienta; Fase 2) Realización de una observación piloto para afinar o incluir nuevas variables; Fase 3) Calculo V de Aiken para analizar la validez de contenido mediante criterio experto; Fase 4) Calculo de validez interna del instrumento criterio de entrenadores superiores; Fase 5) Análisis de la validez intra-observador e inter-observador mediante el índice de correlación de Pearson, coeficiente de correlación intraclase e índice Kappa de Cohen. Podemos afirmar que el instrumento diseñado es válido y fiable para el análisis de las rachas de lanzamiento en el baloncesto profesional masculino.The purpose of this research is to design and validate an ad-hoc observational instrument to analyze shooting streaks in professional basketball. The instrument and its validation was developed in five steps. In the first step a preliminary list of candidates variables was made. In the second step a pilot observation was done to refine or include new variables. In the third and fourth steps the content validity was established and calculated by means of the Aiken's V method respectively. In the fifth step inter and intra observer reliability were tested by using the Pearson's correlation coefficient, the intraclass correlation coefficient and the Cohen's Kappa coefficient. The instrument designed has been proved to be valid and reliable for the analysis of shooting streaks in men's professional basketball
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