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Novel multihost pathogens can threaten endangered wildlife species, as well as humans and domestic animals. The zoonotic protozoan parasite Toxoplasma gondii is transmitted by members of Felidae and can infect a large number of animal species, including humans. This parasite can have significant health consequences for infected intermediate hosts and could further endanger wild carnivore populations of Madagascar. Building on an empirical characterization of the prevalence of the pathogen in local mammals, we used mathematical models of pathogen transmission in a multihost community to compare preventative measures that aim to limit the spread of this parasite in wild carnivores. Specifically, we examined the effect of hypothetical cat vaccination and population control campaigns on reducing the risk of infection by T. gondii in wild Eupleridae. Our model predicted that the prevalence of exposure to T. gondii in cats would be around 72% and that seroprevalence would reach 2% and 43% in rodents and wild carnivores, respectively. Reducing the rodent population in the landscape by half may only decrease the prevalence of T. gondii in carnivores by 10%. Similarly, cat vaccination and reducing the population of definitive hosts had limited impact on the prevalence of T. gondii in wild carnivorans of Madagascar. A significant reduction in prevalence would require extremely high vaccination, low turnover, or both in the cat population. Other potential control methods of T. gondii in endangered Eupleridae include targeted vaccination of wild animals but would require further investigation. Eliminating the threat entirely will be difficult because of the ubiquity of cats and the persistence of the parasite in the environment. [ABSTRACT FROM AUTHOR]

Copyright of GeSec: Revista de Gestao e Secretariado is the property of Sindicato das Secretarias e Secretarios do Estado de Sao Paulo (SINSESP) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

En la Enseñanza de la Dinámica Newtoniana a nivel universitario solemos construir Modelos Mecánicos para la comprensión de la situación Física estudiada. Por lo regular construimos primeramente modelos simples (toy models) que posteriormente iremos sofisticando con la intención de crear un modelo más complejo y por tanto más realista al final. Aseguramos con ello que el modelo sofisticado es mejor que el modelo simple (Estrategia de Modelización Progresiva, EMP). ¿Esto es siempre así?. Presentamos aquí la construcción de Dos Modelos Mecánicos (uno Sofisticado y otro Simple) para estudiar el Movimiento de una Cuerda Masiva que Resbala sobre una Mesa con y sin Fricción Seca y mostramos que los principales resultados obtenidos en el modelo simple son tan buenos y generales como los obtenidos del modelo sofisticado. Lo anterior nos muestra como poder estudiar el problema de la Cuerda que Desliza por una Mesa en diferentes estadios de la Educación Universitaria sin detrimento de la compresión completa del problema planteado. Como complemento a lo anterior discutimos también la versión Lagrangiana del Problema, así como una posible generalización al problema planteado.

En la enseñanza de la Mecánica, es siempre recomendable poder discutir en clase Problemas Integradores y Holísticos. En ese sentido proponemos analizar el clásico problema del Niño Esquimal que resbala por su Iglú desde diferentes puntos de vista, y que sirva como Experiencia de Aprendizaje Mediado (EAM) usando para ello la Estrategia de Modelización Progresiva (EMP). Dicho problema, aparece en la mayoría de los textos de Física General Universitarios y es abordado únicamente con argumentos de Conservación de Energía. En este trabajo lo planteamos y resolvemos usando la “Dinámica Traslacional con y sin Fricción”, “Conservación de Energía”, “Teorema Trabajo-Energía con y sin Fricción”, “Dinámica Rotacional con y sin Fricción” y usando la “Dinámica Lagrangiana con y sin Fricción”, con la intención de mostrar como con un mismo problema se puede resolver de muy diferentes maneras, ayudando al estudiante a integrar sus conocimientos de Mecánica de una forma general.

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Opuntia Brava is the property of Universidad de Ciencias Pedagogicas de Las Tunas, Centro de Documentacion e Informacion Pedagogica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In Brazil, urea is the most used nitrogen (N) fertilizer to improve forage production. However, their excessive use can cause environmental impacts through N losses, such as ammonia (NH3) volatilization. Therefore, the current study adjusted and estimated the NH3 volatilization from urea applied on tropical pastures in three rainfall conditions using mathematical models. Data were collected from Marandu grass (Brachiaria brizantha) fertilized with 50 kg N ha-1 during wet, intermediate, and dry conditions. Ammonia volatilization was measured in five semi-open chambers for 21 days. The linear, quadratic, exponential, Gompertz, Groot, and Richards models were tested for fitting and estimating the NH3 volatilization. The Gompertz, Groot, and Richards models generated predictions similar to the observed data, with a high determination coefficient, indicating a better fit of these equations to data, with precision and accuracy. However, the Groot model was selected due to the lowest root mean square error of prediction (0.29 % total N lost as NH3). The greatest N loss as NH3 volatilization occurred in the wet, followed by intermediate and dry conditions (20.2, 17.0, and 11.3 % total N lost as NH3, respectively). Therefore, nitrogen losses as NH3 volatilization after application of 50 kg N ha-1, as urea source, are altered according to the weather conditions, reaching 20% of N added in the wet rainfall period. The Groot model is recommended for fitting and estimating the NH3 volatilization from urea applied on Marandu grass pastures in the wet and dry rainfall conditions. [ABSTRACT FROM AUTHOR]

Intensification in agriculture affects many insect species, including butterflies. Insect‐resistant crops, such as Bt (Bacillus thuringiensis) maize, which produces a toxin active against Lepidoptera, are an alternative to insecticide sprays. Genetically modified crops are regulated in most countries and require an environmental risk assessment. In the European Union, such assessments include the use of simulation models to predict the effects on nontarget Lepidoptera (NTL). To support the assessment of protected NTL, we extended an individual‐based, stochastic, spatially explicit mathematical model (LepiX) to include a wider range of exposure scenarios, a species‐sensitivity distribution, and an option for repeated exposure of individuals. We applied the model to transgenic maize DAS‐1507, which expresses a high concentration of Bt toxin in pollen that may be consumed by NTL larvae on their host plants nearby. Even in the most conservative scenario without repeated exposure, mortality estimates for highly sensitive species ranged from 41% to 6% at distances of 10–1000 m from the nearest maize field. Repeated exposure can cause additional mortality and thus is relevant for the overall risk assessment. Uncertainties in both exposure and ecotoxicity estimates strongly influenced the predicted mortalities. Care should be taken to include these uncertainties in the model scenarios used for decision‐making. In accordance with other modeling results, our simulations demonstrated that mean mortality may not be safe for protected species. With its high pollen expression, DAS‐1507 maize may pose risks to sensitive and protected butterfly and moth species that may be difficult to manage. High expression of Bt toxin in pollen is unnecessary for controlling target pests. Consequently, we suggest that Bt maize with high pollen expression not be cultivated in regions where protected butterflies are to be conserved. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Production scheduling is one of the most important tasks in manufacturing systems since it allows the allocation of jobs with a certain number of available resources. In the production and service industries, meeting the established commitments with the different customers and production deadlines can lead to higher levels of satisfaction and market competitive advantages. On the other hand, one of the main industries worldwide is the coffee industry. Indeed, coffee is the second most traded commodity in the world. Therefore, this research addresses the optimization of the total tardiness in the scheduling of jobs in parallel machines for a case study in a coffee roaster. This is an NP-hard problem where each job requires the roasting process and, in addition, has an associated delivery time. Each job's processing time depends on the machine that is designated and not all machines can run all jobs. We present the mathematical model to describe the problem using mixed integer linear programming and then it is implemented in Python. Additionally, a mate heuristic model based on the ATC heuristic is proposed in order to reduce the computation time and to reach solutions close to the optimum. This model was evaluated with one thousand instances of real data from the roasting process. The Gurobi optimizer was used to solve the problem. The exact method shows high computational times, so we proposed to first perform the sequencing of jobs and then assign them to the machines by means of a simplified mathematical model. By using the proposed mate heuristic model, an average reduction of 53.98% of the execution time is achieved and with respect to the solution delay, this model achieves a median of 0.0% with respect to the optimum. [ABSTRACT FROM AUTHOR]

A tidal thermal power plant is a system capable of using of ocean thermal gradients to produce electricity. It is a thermal machine in which surface water acts as a heat source, while water extracted from the depths acts as a coolant. The aim is to mathematically model the open cycle or Anderson tidal thermal power plants located on the coast and connected to the electrical system. For that, the bibliography related to the elements that make up this plant was reviewed, each component was mathematically modeled, from the functional diagram proposed by the authors, the model of these plants was obtained in MatLab/Simulink?, which allowed to determine for a given scenario the power produced by the generator and the delivery of electrical energy to the electrical system. [ABSTRACT FROM AUTHOR]

The article aims to investigate validation in mathematical modelling activities with the objective of organizing a framework related to validation in these activities through data triangulation to give coherence and cohesion to the results. For the organization of the framework, a literature review regarding the theme is realized. In addition, an empirical research is carried out with students of a Mathematics Degree course. The gathering of empirical data and the theoretical structure allow to characterize understandings, the importance and ways of carrying out validation in mathematical modelling. Although it can be recognized as the final step in the modelling cycles, validation cannot be thought of as a cumulative process that only begins at the end of the activity and from which only acceptance or refutation results. Instead, it can act as an iterative agent and guide students' decision-making processes, and validation mechanisms can be activated at different stages of the activity. What can be concluded, therefore, is that, even if specific actions are recognized, it is in the validation of the totality of the modelling that the efficiency of validation resides as a means of generating reliability in what can be said about a situation of reality by using mathematics. [ABSTRACT FROM AUTHOR]

In this text we seek understandings, in terms of the teaching and learning process of Mathematics, about the possible articulations between the History of Mathematics (HM) and Mathematical Modeling (MM) revealed in research in the area. To this end, a systematic literature review was carried out, through which we searched for research in databases and national scientific events that addressed topics related to this objective, which led us to the identification of eight works. Through the procedures of Discursive Textual Analysis, initially, we fragmented and unified the data and, later, classified them into categories. From this analytical process, two categories emerged: I - Articulating HM and MM enables teaching and learning processes that generates understanding of the mathematical topics studied and desirable attitudes for the formation of the student and II - Articulating HM and MM makes it possible to highlight the human aspects, social, scientific, and cultural aspects linked to the development of mathematical models and the relationship between mathematics and other areas of knowledge. Based on the emerging categories, potentialities arising from articulations between HM and MM for the teaching and learning process of Mathematics were evidenced, which justify the reasons why it is relevant to do so. [ABSTRACT FROM AUTHOR]

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Copyright of Universitas Scientiarum is the property of Pontificia Universidad Javeriana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Una central maremotérmica es un sistema capaz de aprovechar los gradientes térmicos oceánicos para producir electricidad. Se trata de una máquina térmica en la que el agua superficial actúa como fuente de calor, mientras que el agua extraída de las profundidades actúa como refrigerante. El objetivo es modelar matemáticamente las centrales maremotérmicas de ciclo abierto o de Anderson emplazadas en la costa y conectadas al sistema eléctrico. Para esto se revisó la bibliografía relacionada con los componentes de esta central, se modeló matemáticamente cada componente, a partir del diagrama funcional propuesto por los autores de este trabajo, se obtuvo el modelo de dichas centrales en MatLab/SimulinkÒ, lo que permitió determinar para un escenario dado la potencia producida por el generador y la entrega de energía eléctrica al sistema eléctrico.

El desarrollo de modelos matemáticos han ayudado a explicar comportamiento sociales, económicos y ambientales, para este caso, la construcción de un modelo de combustible de la vegetación del Parque Natural Regional Los Besotes se convierte en fundamental para la toma de decisiones y la gestión del territorio, por lo cual, esta investigación se centró en desarrollarlo mediante imágenes satelitales de la plataforma Landsat 7 ETM+ C2 L1, datos del periodo 2011 a 2020, con el cual se obtuvieron dos modelos de combustibles, resaltando el constituido con los indicadores EVI de Jung, SAVI y ARVI, ya que poseen características atípicas con la morfología del terreno y consideran variables físicas externas en sus fórmulas. Los modelos fueron predichos a una probabilidad inferior a Alpha (p-value < 0,05), lo que indica una excelente predicción de la combustión vegetal.

Las concepciones que presenta el profesorado sobre modelización matemática inciden en la manera en la cual el proceso matemático se aborda en el aula y en las estrategias de enseñanza utilizadas. El objetivo de esta investigación fue caracterizar el significado y perspectivas en modelización matemática de un grupo docente formador de la carrera Enseñanza de la Matemática. El estudio fue cualitativo. Se aplicó una entrevista virtual a 28 docentes, en el segundo semestre del 2021. El instrumento aplicado contó con la anuencia de las personas docentes a participar de la investigación, e incluía una descripción sobre la confidencialidad de la información. Para el análisis de la información se utilizó el análisis de contenido. Dentro de los resultados se puede mencionar que el significado que le otorgan las personas docentes formadoras al proceso de modelización está ligado a la resolución de problemas, sin una relación estrecha con el contexto que se plantea. Dentro de las dificultades que mencionan y que inciden en el estudiantado al momento de enfrentarse a problemas de modelización, está la comprensión del problema que, en opinión de estos, se debe a una carencia de conocimientos algebraicos. Se determinó que el planteamiento de problemas con un conocimiento matemático específico, para el tratamiento o uso de datos, es una de las estrategias de enseñanza más utilizadas para el abordaje de la modelización matemática. Además, se indica que, para la incorporación de la modelización en los planes de estudio de formación de docentes de matemática, es necesario abordar el conocimiento de estos sobre los procesos de modelización, así como un adecuado planeamiento e incorporación de este tipo de actividades.

Copyright of GeSec: Revista de Gestao e Secretariado is the property of Sindicato das Secretarias e Secretarios do Estado de Sao Paulo (SINSESP) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Diversos estudios han demostrado que la sensibilidad a la insulina presenta fluctuaciones durante la fase lútea y folicular del ciclo menstrual que pueden generar alteraciones en el comportamiento del nivel de glucosa. Diversos estudios han demostrado que la sensibilidad a la insulina presenta fluctuaciones durante la fase lútea y folicular del ciclo menstrual que pueden generar alteraciones en el comportamiento del nivel de glucosa. Conocer la relación entre las fases del ciclo menstrual y la resistencia a la insulina es un objetivo de salud personalizada, enfocada a la mejora de la calidad de vida. En esta investigación se propone una modificación al modelo matemático desarrollado por Dalla Man et al. (Dalla Man, C., Rizza, R. A., & Cobelli, C., 2007) para incluir las diferentes etapas del ciclo menstrual sobre el comportamiento del nivel de glucosa en la sangre, teniendo en cuenta cambios en la sensibilidad a la insulina y el valor basal de glucosa en la sangre. Para comprobar el comportamiento del nivel de glucosa durante el ciclo menstrual descrito en la literatura se realizó una prueba de tolerancia a la glucosa en una individua sana regularmente menstruante y se comparó con resultados de simulación in-vitro. Los resultados permiten observar comportamiento descrito en el modelo propuesto al relacionar las diferentes fases del ciclo menstrual y la resistencia a la insulina.

El estudio se realizó en la Universidad Estatal del Sur de Manabí en la carrera de ingeniería civil con el objetivo de determinar las causas del mal estado de las vías de la zona urbana del cantón Jipijapa a partir del desarrollo de un modelo computacional. El tipo de investigación que se realizó es documental-bibliográfica ya que para poderla realizar nos sustentamos en un marco teórico existente y con ellos obtener información sobre el mal estado de las calles en la zona urbana del cantón Jipijapa. En el trabajo de campo se aplicaron encuestas al sector afectado, las cuales fueron punto clave al momento de determinar el malestar e incidencia que causa el mal estado de las calles. Se aplicó un modelo matemático basado en operadores de agregación con el propósito de destacar las causas que provocan el mal estado de las calles como son el tipo de suelo y el tipo de pavimento o asfalto colocado en ellas. Se realizó un análisis teórico de los elementos que determinan las causas del deterioro de las vías del cantón Jipijapa tales como el suelo características, tipos de suelo, efectos del clima sobre el desempeño del pavimento, efectos de la temperatura en la estructura del pavimento, cambio de humedad, entre otros. Se determinó que los factores que determinan el deterioro de las vías en Jipijapa son hundimiento del suelo, no hay proyectos de mejoramiento de la zona urbana del cantón Jipijapa, deterioro prematuro de calles, desacertado estudio del suelo, baches y materiales de baja calidad.

As mudanças climáticas, suas consequências e alternativas para minimizar seus efeitos estão entre os temas mais debatidos atualmente. Os sistemas de integração Lavoura-Pecuária-Floresta (iLPF) aparecem como uma alternativa na concepção de Agricultura Sustentável. Para o manejo da iLPF, o sensoriamento remoto tem se mostrado uma opção. Nesse estudo, conduzido numa área experimental de iLPF, em Pinhais, PR, foi analisado a variabilidade dos índices de vegetação (NDVI, sPRI e CO2flux) entre fevereiro e setembro de 2021, utilizando imagens da PlanetScope, em dois níveis de análise: nível de pixel e tratamento. No nível de pixel, os resultados indicaram leve tendência de queda do NDVI; estabilização dos valores de CO2flux; e leve aumento do sPRI. Enquanto, para o nível de tratamento, as tendências do NDVI e sPRI se mantiveram; já o CO2flux, foi observado uma queda em seus valores. Utilizando o teste de ANOVA, foi mostrado que não houve variação entre os índices para os diferentes tratamentos. Também foi analisada uma variável climática – precipitação – na atuação sobre os índices. Pela regressão linear múltipla, os valores do nível de pixel relacionados com os valores de biomassa do inventário florestal, como subsídio para a estimativa da biomassa acima do solo, demonstraram relações nulas a fracas

El presente trabajo tiene por objetivo desarrollar un modelo matemático predictivo que otorgue un primer acercamiento al valor de requerimiento energético (RE) de un edificio en un clima templado continental, con el propósito de aportar al conocimiento teórico sobre herramientas de evaluación energética. Se realizaron simulaciones paramétricas procesadas con los programas EnergyPlus 9.5 y JePlus. Los resultados fueron utilizados como Dataset para el armado de diferentes modelos matemáticos, para los cuales se utilizó el programa SageMath a fin de desarrollar ecuaciones que predigan el RE de cada escenario. Se trabajó con modelos escalonando su complejidad en cuanto a métodos utilizados y cantidad de parámetros. Se seleccionó un modelo con bajo nivel de error (0.08) y 15 parámetros. Se advirtió que, si bien el aumentar la cantidad de parámetros acercaba los modelos al error 0.02, se corría el peligro de overfitting. El modelo seleccionado busca incorporar la precisión y validez de las simulaciones dinámicas a una herramienta de predicción sencilla y aplicable por profesionales de la construcción.

En el presente trabajo se propone un modelo no lineal y se estiman series para las poblaciones involucradas en el fenómeno del suicidio con información demográfica del DANE y boletines epidemiológicos de Sivigila para el departamento del Tolima. Se introducen las poblaciones vulnerables, susceptibles, en tratamiento y población, que han terminado un tratamiento o ayuda psicológica contra el suicidio y se estiman proyecciones de estas poblaciones hasta el año 2034. Se establecen relaciones lineales y no lineales entre poblaciones involucradas en el fenómeno del suicidio que permiten definir condiciones iniciales y estimación de parámetros con el método de Levenberg-Marquardt, para obtener series poblacionales hasta el año 2034 bajo la evolución dinámica de un modelo no lineal empleando el Software Matlab R2021a. Como resultado, se establecen supuestos entre variables de estado que permiten acotar y estimar las constantes de proporcionalidad; se propone un diagrama causal de la interacción dinámica de las variables de estado con respectivos supuestos que permiten formular el modelo matemático de la interacción dinámica del suicidio, el cual se normaliza para obtener estimaciones de las proyecciones de las series de población. Finalmente, se concluye que en el departamento del Tolima muestra un comportamiento creciente de casos de suicidio, donde el 99,84 % de la población vulnerable se expone a factores desencadenantes y un porcentaje inferior al 0,11 % recibe tratamiento, con una tasa de efectividad inferior del 0,05 %. Se invita a entes de salud pública a desarrollar estrategias que bajen las tasas de mortalidad por esta causa.

Copyright of Paradigma is the property of Universidad Pedagogica Experimental Libertador and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of the research is based on presenting the results of a prediction model of homicides from logistic regression in the metropolitan district of Quito - Ecuador. The research approach was quantitative with a descriptive scope. Step 7 indicates a Wald value of 9.284 and significance of 0.002 for the variable place where the homicide was committed (1), indicating 1 for the alternative "public road", with a value for Exp(B) of 0.08, so the model predicts that people have a probability of 0.08 of suffering a homicide on a public road compared to another place where they are. The model predicts that the public road is the place where there is the highest probability of homicide, equally for people of all ages, genders, nationalities. [ABSTRACT FROM AUTHOR]

Polyhydroxyalkanoates (PHAs) have become important due to their mechanical properties, which resemble those of plastics derived from petrochemicals. Despite the advantages they possess, its use is limited by production costs. In terms of the culture systems used for process improvement, fed batch systems are the most studied, since they allow higher productivity to be obtained. In this study, PHAs production was reviewed with a new feeding model against the reported exponential model and under improved culture conditions. In the results, the predictive feeding strategy allowed to improve the production of PHAs (24.1 ± 1.14 g/L) by controlling the concentration of residual substrate, with respect to the exponential model (18.1 ± 1.33 g/L), achieving a biomass concentration of 40.9 ± 1.12 g/L and a polymer productivity of 1.01 gPHA/L.h, improving the process by 25%. [ABSTRACT FROM AUTHOR]

The development of mathematical models have helped to explain social, economic and environmental behavior, for this case, the construction of a fuel model of the vegetation of the Los Besotes Regional Natural Park becomes essential for decision making and land management, therefore, this research focused on developing it through satellite images from the Landsat 7 ETM+ C2 L1 platform, data from the period 2011 to 2020, with which two fuel models were obtained, highlighting the one made up of Jung's EVI, SAVI and ARVI indicators, since they have atypical characteristics with the morphology of the terrain and consider external physical variables in their formulas. The models were predicted at a probability lower than Alpha (p-value < 0.05), indicating an excellent prediction of plant combustion. [ABSTRACT FROM AUTHOR]

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Copyright of Actualidades Pedagógicas is the property of Revista Actualidades Pedagogicas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Anaerobic digestion (AD) is a process of decomposition of organic matter in which the main product is a gaseous mixture called biogas, which has potential as a fuel. Anaerobic co-digestion (ACoD) is a technological alternative to improve the performance of the process, focused on balancing the C/N ratio and diluting inhibitory components. The literature highlights the increase in methane yield through ACoD. This investigation analyzed the mixing effects on methane yield kinetics, using articles that report kinetic coefficients in Cone and Gompertz models modified for binary and ternary mixtures. The analysis of the mixtures considered the sum of the contributions for each mixture using the adjusted kinetic coefficients for the monosubstrates. The mixing effects analysis compared the additive model fitted to the modified Cone and Gompertz models. The comparison made with the coefficients for the additive model and the experimental data presented relevant variations of 10%. This allowed to establish that the mixing effects can influence the methane yield as well as the kinetic constants of the process. [ABSTRACT FROM AUTHOR]

Animal species change their residence places due to the high temporal variability in the availability of resources. Thus, animals move to sites with higher productivity and they search environments with the necessary resources that allow it to develop the different stages of their life cycle. Here, we present a simple mathematical model that determines a no extinction condition (stable oscillation) in terms of the movement parameters for obligate-migration populations. We understand the obligate-migration as a movement seasonally predictable in distinct locations, which is associated with patterns of resource distribution. [ABSTRACT FROM AUTHOR]

La gulupa es uno de los frutos que ha aumentado sus exportaciones desde Colombia en los últimos 15 años, debido a sus características organolépticas. Conocer el área foliar (AF) en este cultivo es importante; sin embargo, no se conocen métodos prácticos que permitan su cálculo. El objetivo fue desarrollar modelos no destructivos para estimar el AF individual, mediante parámetros alométricos en hojas de gulupa. El AF se determinó en 100 hojas, mediante dos métodos estándar: el medidor portátil láser CI-202 y el software Easy Leaf Area (ELA). Se midió la longitud del lóbulo central (L), el lóbulo derecho (LD) e izquierdo (LI), el ancho base en los lóbulos (a) y el ancho entre las puntas terminales de los lóbulos (b) y se calculó la longitud total (Lt), como la suma de L+LD+LI. Los modelos lineales con mayor coeficiente de determinación (R2) fueron los que relacionaron las variables L*a (0,9377; 0,9756) y Lt*a (0,9430; 0,9841), para el AF, medida con el CI-202 y con el ELA respectivamente, frente al AF estimada. Se validaron R2 de 0,9336 y 0,9612, entre el área de la hoja medida en la localidad de Arcabuco y la estimada con L*a para los dos métodos empleados, mientras que para la estimación del AF con base en Lt*a, se encontraron R2 de 0,9552 y 0,9680, lo que convierte al método ELA como el más confiable para medir el AF y que la variable alométrica Lt*a permite encontrar la mejor predicción de AF individual en hojas de gulupa.

Como parte del trabajo de Investigación Didáctica que realizamos en el Depto. de Postgrado del CIIDET, presentamos como Estrategia de Enseñanza de la Mecánica Clásica, la Construcción Progresiva del Modelo Clásico de Dos Bloques atados con un hilo que resbalan sobre una mesa y que pasa por una Polea, desde el más simple hasta el que considera fricción y masa en el hilo. Dicho modelo es considerado en la mayoría de los textos y cursos de bachillerato y pregrado universitario como instrumento para estudiar las Leyes Dinámicas de Newton. Creemos que con esta propuesta el instructor podrá transitar desde la Educación Media Superior hasta la Superior sin grandes dificultades y usando en principio el mismo Modelo arquetípico, ayudando a sus alumnos a fijar las ideas correspondientes.

The greatest problems that has been presented in the world, especially in Colombia, is due to an accelerated population growth generated by the overwhelming increase in migrant circulation or mobility of people due to other causes or eventual situations of nature. These social situations have been significantly affecting the urban order of cities, particularly due to the confinement of the population and the increase in environmental pollution that this increase brings, in addition to unhealthiness, poverty, among other factors. To study population growth based on demographic variables and environmental factors, an Artificial Neural Network was built to carry out a data analysis that incorporated related variables such as CO2 and other pollutants. The purpose was to identify the influence of these toxic agents with the growth of a population. Once the dynamic prediction was verified through the neural network, a mathematical model was built to study a specific case of demographic behavior for a certain Colombian region by means of a Forrester Diagram, where the migratory conditions, birth rate, morbidity, mortality, migratory flow (or mobility of people due to other natural events) and pollutants that affect human health mainly in respiratory diseases. The results delivered predictions and the Forrester Diagram confirming the relationship between toxic agents and demographic aspects. [ABSTRACT FROM AUTHOR]

The purpose of this research is to develop a Mathematical Modeling for a Damping System Applied to the Retractable Landing Gear of an Aircraft. It will be supported theoretically by authors such as como Zill, Dennis G. (2007) and Ogata, K. (2010) for the mathematical model study variable for a damped system. The research is of a descriptive explanatory type, with a non-experimental design, the population and case study was defined by a unit of analysis which is specified as the landing gear damping system of a Beechcraft Super King air B 200 aircraft. methodology to be used with 4 phases: (1) Explain the different types of damping systems used in the landing gear of a fixed-wing aircraft, propeller or jet category. (2) Identify the general characteristics of the input and output variables, as well as the parameters involved in the damping of the retractable landing gear of a Beechcraft Super King Air B 200 aircraft. (3) Establish the mathematical model that describes the retractable landing gear suspension system of a Beechcraft Super King Air B 200 aircraft. (4) Validate the mathematical model described by applying an analytical type test that involves the use of a set of mathematical and graphic relationships using Matlab software. It is recommended for a future study to add an external force F(t) to the differential equation of motion, which would create a new mathematical model that would represent a more real and general but more complex phenomenology. [ABSTRACT FROM AUTHOR]

In this work, the mathematical model of a muscle-tendon used for the design of a rotator-type joint actuated by artificial muscles is shown. Computer-aided design (CAD) allows evaluating and validating the most convenient parameters for its construction; the integration of the CAD model with MATLAB allowed us to obtain the values of the range of motion ±20◦ and a maximum torque of 6.0 kg-cm exerted on the axis of rotation for the prototype. [ABSTRACT FROM AUTHOR]

The Cuban fishing industry is optimizing its processes in the face of continuous change: economic, financial, and social. Decisions made with scientific support are required to maximize the economic and financial benefits with a social focus. This approach is inherent to the Cuban state business system and must respond to the restrictions imposed by the internal and external environment. Therefore, a monthly linear programming model is presented for production planning in the fish processing industry in Santiago de Cuba that contributes to effective decision-making. Application of the model in an entity allows decision-makers to know the most profitable products and raw materials and improve production while complying with the restrictions of the production process. [ABSTRACT FROM AUTHOR]

The purpose of this article is to discuss the conditions that would make it possible for the Mathematical Modelling argument to emerge in Brazilian Mathematics Education. To this end, we have used theoretical and methodological resources linked to theories by the philosopher Michel Foucault. The analytical material covers master’s and doctoral theses developed in Brazil between the years 1976 and 1999, which have conceptualized Mathematical Modeling in Mathematics Education. The analysis of such studies has made it evident that the concept of Mathematical Modeling occurs during a crisis in Mathematics teaching, which has been discussed here from the following statement: “Mathematics is distant from reality”. We could conclude that the Modern Mathematics Movement made the emergence of Mathematical Modeling possible in Mathematics Education. The reason for that is that it would provide for interdisciplinary work - minimizing the distance between Mathematics and reality - thus, it would bring meaning to the teaching and learning of Mathematics - mitigating the difficulties students go through to learn it. [ABSTRACT FROM AUTHOR]

Copyright of Revista Ciência Agronômica is the property of Revista Ciencia Agronomica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ricercare is the property of Universidad EAFIT and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Technological Development / Revista del Desarrollo Tecnológico is the property of ECORFAN-Mexico S.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

En la presente investigación surgió la necesidad de utilizar herramientas didácticas que permitieran conocer la mejor optimización de un sistema fotovoltaico para el abastecimiento de las cargas de una bananera. En correspondencia a lo anterior, este estudio presenta un modelo y simulación de un sistema conectado a la red, considerando la variación de la irradiancia solar. En primera instancia, se utilizó el instrumento piranómetro en la zona a estudiar. Luego se consideró las cargas de la bananera, para luego hacer uso de la herramienta HOMER Pro para hallar la mejor viabilidad del sistema fotovoltaico con sus algoritmos de optimización. Para su validación se utilizó otros algoritmos de modelos matemáticos realizados en Matlab/Simulink, estableciendo la potencia del sistema, el costo nivelado de energía ($/kWh), como también el voltaje (V), corriente (A) y potencia (W) tanto del panel solar como la energía que sale a la carga, además, se determinó el punto de máxima transferencia de potencia (MPPT) del sistema. Por último, se evaluó el payback del modelamiento para conocer el tiempo de retorno de la inversión del sistema.

Objetivo: Diseñar un procedimiento para la medición de la gestión de la planificación del proceso de mantenimiento con apoyo de la lógica difusa, y lograr un modelo matemático para conformar un indicador que mida el estado de esta. Métodos: Se utilizan los métodos empíricos y teóricos para el análisis y síntesis de la medición de la planificación del proceso de mantenimiento, así como su relación con la planificación empresarial y la toma de decisiones. Se empleó la búsqueda bibliográfica, modelación de procesos y modelación matemática mediante la lógica difusa, criterio de expertos, así como los softwares Microsoft Office Excel y Minitab. Principales resultados: El procedimiento brinda como resultado una evaluación de la situación actual de la planificación, para tomar oportunamente las decisiones necesarias, en cuanto a la asignación de recursos materiales y humanos. Conclusiones: El valor del indicador obtenido, estado de la planificación del mantenimiento, es regular, con un valor de 0,615 2, siendo las variables recursos e información las más deficientes; esto se relaciona con las etapas de organización y ejecución de la planificación del mantenimiento. La incertidumbre en el proceso de planificación del mantenimiento, justifica aplicar la lógica difusa como herramienta para modelar de manera sencilla el proceso de evaluación, teniendo en cuenta el grado de dificultad de las variables del proceso.