Mixing across fluid interfaces compressed by convective flow in porous media

We study the mixing in the presence of convective flow in a porous medium. Convection is characterized by the formation of vortices and stagnation points, where the fluid interface is stretched and compressed enhancing mixing. We analyze the behavior of the mixing dynamics in different scenarios using an interface deformation model. We show that the scalar dissipation rate, which is related to the dissolution fluxes, is controlled by interfacial processes, specifically the equilibrium between interface compression and diffusion, which depends on the flow field configuration. We consider different scenarios of increasing complexity. First, we analyze a double-gyre synthetic velocity field. Second, a Rayleigh-B\'enard instability (the Horton-Rogers-Lapwood problem), in which stagnation points are located at a fixed interface. This system experiences a transition from a diffusion controlled mixing to a chaotic convection as the Rayleigh number increases. Finally, a Rayleigh-Taylor instability with a moving interface, in which mixing undergoes three different regimes: diffusive, convection dominated, and convection shutdown. The interface compression model correctly predicts the behavior of the systems. It shows how the dependency of the compression rate on diffusion explains the change in the scaling behavior of the scalar dissipation rate. The model indicates that the interaction between stagnation points and the correlation structure of the velocity field is also responsible for the transition between regimes. We also show the difference in behavior between the dissolution fluxes and the mixing state of the systems. We observe that while the dissolution flux decreases with the Rayleigh number, the system becomes more homogeneous. That is, mixing is enhanced by reducing diffusion. This observation is explained by the effect of the instability patterns

Beyond the prototypical: Developing a behavioral screening tool of same-gender male intimate partner violence.

In the United States, intimate partner violence (IPV) is estimated to be among the top three health issues impacting gay and bisexual males. Previous studies of IPV prevalence in this population result in epidemiological inconsistencies largely due to unreliable measurement. Behavioral tools employed in research and in clinical settings often apply a heterosexist and prototypical model to IPV screening; thereby, failing to contextualize occurrences of violence in a same-gender IPV relationship. Despite the estimated impact of IPV among gay/bisexual men, no known literature has attempted to create a behavioral screening tool that accounts for contextual factors in same-gender relationships characterized by IPV. The current study determined the essential theoretical constructs of a clinical screening tool for males involved in same-gender IPV relationships. Two groups of key informants participated in the study – men who have been in same-gender relationships involving partner violence (MSRV) and community mental health providers (MHP) with varying degrees of experience treating this population. Qualitative data collection and analyses occurred in four stages, and were informed by a participatory action research framework. Key informants provided insights regarding how they defined same-gender IPV, their experiences screening or being screened for same-gender IPV, their recommendations for the effective screening of IPV in MSRV, and (in the final stage) feedback related to the preliminary screening tool’s content, format, and structure. Future research should focus on adapting this tool for research purposes

Evolution of dissolution patterns by mixing corrosion in karst systems

Póster presentado en la European Geosciences Union General Assembly, celebrada en Viena del 27 de abril al 2 de mayo de 2014.Conduit enlargement in a karst system is usually assumed to be controlled by non-linear kinetics that allow aggressive water to penetrate along fractures (Gabrovšek and Dreybrodt, 2000, Water. Resour. Res.). However, other mechanism known as mixing corrosion may be decisive for the geometry of the resulting dissolution patterns, at least at depth. Mixing corrosion is caused by the renovation of the dissolution capacity that happens when two waters saturated with respect to calcite but with different CO2 partial pressure mix. In this case, the reaction rate is mixing-controlled and can be quantified in terms of the mixing proportion of the conservative components of the chemical system (De Simoni et al. 2005, Water. Resour. Res.). Therefore, the porosity creation governed by the reaction rate will depend on the chemical differences between the end members and by the degree of mixing. The aim of this work is to study the evolution of the porosity and permeability within a carbonate matrix by mixing-driven dissolution under different diffusion regimes. The speciation of the chemical system is calculated using CHEPROO. Flow and transport are modeled using an ad hoc code that accounts for feedback between reactions, porosity creation and permeability changes. The effects of the initial porosity field, water chemistry and the resulting geometry of the dissolution patterns are explored for different scenarios.Peer reviewe

An experimental and modelling exploration of the host-sanction hypothesis in legume-rhizobia mutualism

Despite the importance of mutualism as a key ecological process, its persistence in nature is difficult to explain since the existence of exploitative, 'cheating' partners that could erode the interaction is common. By analogy with the proposed policing strategy stabilizing intraspecific cooperation, host sanctions against non N2 fixing, cheating symbionts have been proposed as a force stabilizing mutualism in legume-Rhizobium symbiosis. Following this proposal, penalizations would include decreased nodular rhizobial viability and/or early nodule senescence in nodules occupied by cheating rhizobia. In this work, we analyze the stability of Rhizobium-legume symbiosis when "cheating" strains are present, using an experimental and modelling approach. We used split-root experiments with soybean plants inoculated with two rhizobial strains, a cooperative, normal N2 fixing strain and an isogenic non-fixing, “perfect” cheating mutant derivative that lacks nitrogenase activity but has the same nodulation abilities inoculated to split-root plants. We found no experimental evidence of functioning plant host sanctions to cheater rhizobia based on nodular rhizobia viability and nodule senescence and maturity molecular markers. Based on these experiments, we developed a population dynamic model with and without the inclusion of plant host sanctions. We show that plant populations persist in spite of the presence of cheating rhizobia without the need of incorporating any sanction against the cheater populations in the model, under the realistic assumption that plants can at least get some amount of fixed N2 from the effectively mutualistic rhizobia occupying some nodules. Inclusion of plant sanctions merely reduces the time needed for reaching plant population equilibrium and leads to the unrealistic effect of ultimate extinction of cheater strains in soil. Our simulation results are in agreement with increasing experimental evidence and theoretical work showing that mutualisms can persist or even improve in presence of cheating partners

Noxious Iron–Calcium Connections in Neurodegeneration

Iron and calcium share the common feature of being essential for normal neuronal function. Iron is required for mitochondrial function, synaptic plasticity, and the development of cognitive functions whereas cellular calcium signals mediate neurotransmitter exocytosis, axonal growth and synaptic plasticity, and control the expression of genes involved in learning and memory processes. Recent studies have revealed that cellular iron stimulates calcium signaling, leading to downstream activation of kinase cascades engaged in synaptic plasticity. The relationship between calcium and iron is Janus-faced, however. While under physiological conditions iron-mediated reactive oxygen species generation boosts normal calcium-dependent signaling pathways, excessive iron levels promote oxidative stress leading to the upsurge of unrestrained calcium signals that damage mitochondrial function, among other downstream targets. Similarly, increases in mitochondrial calcium to non-physiological levels result in mitochondrial dysfunction and a predicted loss of iron homeostasis. Hence, if uncontrolled, the iron/calcium self-feeding cycle becomes deleterious to neuronal function, leading eventually to neuronal death. Here, we review the multiple cell-damaging responses generated by the unregulated iron/calcium self-feeding cycle, such as excitotoxicity, free radical-mediated lipid peroxidation, and the oxidative modification of crucial components of iron and calcium homeostasis/signaling: the iron transporter DMT1, plasma membrane, and intracellular calcium channels and pumps. We discuss also how iron-induced dysregulation of mitochondrial calcium contributes to the generation of neurodegenerative conditions, including Alzheimer’s disease (AD) and Parkinson’s disease (PD)

“Prevalencia de caries interproximales en premolares de estudiantes de la Escuela de Estomatología de la Universidad César Vallejo, según la clasificación de Pitts modificada, Piura 2017 – 2018”

La presente investigación fue de tipo descriptiva y de corte longitudinal retrospectivo y tuvo como objetivo determinar Prevalencia de caries interproximales en premolares de estudiantes de la Escuela de Estomatología Universidad César Vallejo, según la Clasificación de Pitts modificada, Piura 2017 - 2018. Antes del estudio se realizó la calibración entre especialista y el investigador a través de un análisis de concordancia. Se realizó un muestreo no probabilístico por conveniencia. La muestra estuvo constituida por 208 premolares de estudiantes que cursaban la experiencia curricular de imagenología durante semestres 2017 II y 2018 I. La ejecución consistió en la toma de placas radiográficas de tipo Bitewing para el diagnóstico de caries interproximal en premolares. Se encontró que la prevalencia fue de 50 premolares afectados por caries dental interproximal (24%), según a técnica bitewing en la escala de Pitts los resultados indican que el 78% fueron R1, 14% de R2, 6% de R3, 0% de R4 y 2% de R5, siendo R1 la más prevalente con 24%. De acuerdo a la ubicación en el maxilar, el más prevalente se dio en el maxilar superior con 62%. Según las superficies proximales afectadas, La superficie distal fue la más afectada con 76%. Se concluye que la mayor prevalencia de lesiones cariosas interproximales f se presentó en estadios iniciales (R1), y en la superficie distal del maxilar superior

Aplicación del mantenimiento productivo total para reducir costos operativos en una empresa metalmecánica, Trujillo - 2021

El presente trabajo tuvo como objetivo determinar la aplicación del TPM (mantenimiento productivo total) para disminuir los costos operativos en la línea de producción de mangueras hidráulicas de la empresa metal mecánica de la ciudad de Trujillo, 2021. En primer lugar, se efectúa un diagnóstico situacional de la empresa, para hallar los problemas existentes, para este fin se utilizó el Diagrama de Ishikawa; identificando problemas de falta de capacitación a operarios, averías contantes en maquinaria, falta de procedimientos estandarizados y desorden en planta; obteniendo un costo actual total de S/ 176,147.67 soles al año. Para la solución de dichas causas, se aplicó un plan de Mantenimiento Preventivo Total (TPM), la herramienta 5s y por último la elaboración de un Programa Anual de capacitación, mantenimiento autónomo y entrenamiento; de esta manera se observa la reducción de costos operativos en la empresa metalmecánica de la ciudad de Trujillo, 2021. Además, una vez aplicada el Mantenimiento Preventivo Total (TPM) se obtiene como resultado una reducción de S/ 93,246.94 soles al año, lo que significa un 53 % de ahorro con respecto a costos. Asimismo, tenemos un aumento en el porcentaje de evaluación de formato 5’S de 50% a 100%, con una disminución en costos gracias a un Plan de capacitación que se redujo de 81% a 19%, a la vez se obtuvo una disminución de 144 averías en 84 averías al año con un tiempo medio de reparación de 19.8 hr/año a 9.24 hr/año. Para concluir, con respecto a los indicadores financieros se realizó una evaluación económica obteniendo un VAN de S/ 144,728.67, un TIR de 79% y un B/C de 3.67. Lo cual se concluye que la aplicación de mejora es viable y reduce los costos operativos para la empresa

Novedades para las aráceas costarricenses (Araceae) con notas nomenclaturales

Background and Aims: Araceae is a worldwide family of herbaceous plants, most notable for its striking morphological diversity and broad habitat diversity. It comprises eight subfamilies, 143 genera, and 3667 species. The Central American region has about 780 species, of which 262 are distributed in Costa Rica. In this contribution, we include four new aroid records for the Costa Rican flora belonging to the genera Anthurium, Philodendron, and Spathiphyllum. In addition, nomenclatural aspects of A. myosuroides are discussed. Methods: The new records resulted from fieldwork on Fila Anguciana, Cerro Turrubares, and Volcán Miravalles. The correct taxonomic identity of the species was confirmed based on literature and comparison with herbarium specimens, especially type specimens from the herbaria of the Universidad de Panama (PMA) and the Missouri Botanical Garden (MO), as well as consultation of the JSTOR Global Plants database and the collections of the Muséum National d'Histoire Naturelle de Paris (P) online. Descriptions, taxonomic discussions, and figures of the morphological characteristics of the new records are provided. Key results: We present Anthurium roseospadix, A. myosuroides, Philodendron pseudauriculatum and Spathiphyllum dressleri as new records for the Costa Rican flora. Moreover, lectotypification for Pothos myosuroides is proposed. Conclusions: Considering the new records presented in this work, the aroid flora of Costa Rica now comprises 266 species, and the total species numbers for Anthurium, Philodendron, and Spathiphyllum increased to 94, 63, and 10, respectively.Antecedentes y Objetivos: Araceae es una familia de plantas herbáceas ampliamente distribuida en el mundo, es notable por su sorprendente diversidad morfológica y su vasta variedad de hábitats. La familia comprende ocho subfamilias, 143 géneros y 3667 especies. La región centroamericana posee alrededor de 780 especies, de las cuales 262 se encuentran en Costa Rica. En esta contribución, incluimos cuatro nuevos registros de aráceas para la flora de Costa Rica, pertenecientes a los géneros Anthurium, Philodendron y Spathiphyllum. Adicionalmente, se discuten aspectos nomenclaturales de A. myosuroides. Métodos: Los nuevos registros se realizaron mediante trabajo de campo en Fila Anguciana, Cerros Turrubares y Volcán Miravalles. La correcta identidad taxonómica de las especies se confirmó mediante la revisión de literatura y por comparación con especímenes de herbario, especialmente los ejemplares tipo provistos por los herbarios de la Universidad de Panamá (PMA) y el Jardín Botánico de Missouri (MO). También se consultó, en línea, la base de datos de JSTOR Global Plants y la colección del Muséum National d’Histoire Naturelle de París (P). Se proporcionan descripciones, discusiones taxonómicas e ilustraciones de las características morfológicas de los nuevos registros. Resultados clave: Se presentan Anthurium roseospadix, A. myosuroides, Philodendron pseudauriculatum y Spathiphyllum dressleri como nuevos registros para la flora de Costa Rica. Además, se propone una lectotipificación para Pothos myosuroides. Conclusiones: Considerando los nuevos registros presentados en este trabajo, la flora de aráceas de Costa Rica ahora comprende 266 especies, donde la diversidad de Anthurium, Philodendron y Spathiphyllum aumentó a 94, 63 y 10 especies, respectivamente

Diseño de modelo de gestión para el gerenciamiento de la seguridad de la información tecnológica en el Consejo de la Judicatura – planta central Quito

Ecuadorian state entities handle and process technological information daily, that is exposed to risks of loss, manipulation or copy; so that it is important to have mechanisms and technological systems that ensure the protection of information generated by institutional users and citizenship, based in laws, rules and regulations of the institution or public service. The research of design model for the management of security of information technology in the Judicial Council, central plant in Quito, which are intended to generate a model of management of security information to protect and safeguard the institutional information technology, therefore, a diagnosis and analysis of vulnerabilities of information in the Judicial Council2, whose service is to provide justice to the entire Ecuadorian population nationwide through of Judicial Units; therefore, the content of this work whose propose is developing a management model that allows the articulation of institutional strategic plan, functions and products established in relation to information security, according to Status of Organizational Management by Processes Judicial Council to Central and Decentralized level.Las entidades del Estado ecuatoriano manejan y procesan información tecnológica diariamente, la misma que está expuesta a riegos de pérdida, manipulación o copiado, por lo que es imperativo contar con mecanismos y sistemas tecnológicos que garanticen la protección de la información generada por los usuarios institucionales y de la ciudadanía (público y privado), enmarcados en leyes, reglamentos y normativas institucionales o del servicio público. Este trabajo de investigación de Diseño de modelo de gestión para el gerenciamiento de la seguridad de la información tecnológica en el Consejo de la Judicatura, planta central Quito, tiene por objetivo generar un modelo de gerenciamiento de la seguridad de la información para proteger y resguardar la información tecnológica institucional, por lo cual, se realizará un diagnóstico y un análisis de las vulnerabilidades de la información en el Consejo de la Judicatura, que ofrece servicios judiciales a toda la población ecuatoriana a nivel nacional a través de sus Unidades Judiciales1; por lo tanto, el contenido del presente trabajo tiene como fin la elaboración de un modelo de gestión que permita la articulación del Plan Estratégico Institucional, las atribuciones y productos establecidos en relación a la seguridad de la información, de acuerdo al Estatuto Integral de Gestión Organizacional por Procesos del Consejo de la Judicatura a Nivel Central y Desconcentrad