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Mathematical analysis of a metapopulation model for dengue dynamics
No full textNo es una novedad que el crecimiento de las poblaciones urbanas está aumentando, especialmente en zonas de bajos recursos. Dicho crecimiento viene acompañado de servicios de saneamiento ambiental deficientes y falta de recursos para el almacenamiento adecuado del agua, lo que ha favorecido el crecimiento de la población de mosquitos y, por ende, la propagación del dengue. El dengue es una enfermedad viral transmitida principalmente por los mosquitos Aedes aegypti que constituye uno de los mayores problemas de salud pública. El análisis cualitativo y cuantitativo de la propagación de esta enfermedad es de suma importancia para la sociedad, pues permite plantear un plan de choque para la prevención de una epidemia. Presentamos el análisis de un modelo metapoblacional del tipo SIR-SI que representa la dinámica del dengue para dos zonas conectadas por los tiempos de permanencia de la población humana en ellas, así como el análisis cualitativo del modelo, considerando diferentes escenarios de conexión entre las dos zonas estudiadas.Palabras claves: Dengue; Metapoblación; Modelamiento matemático; Número reproductivo básico.The growth of urban populations is increasing especially in areas with low resources. Such growth has been accompanied by deficient sanitation services and a lack of resources for storing water in adequate ways helping to the increase of the mosquito population and, consequently, dengue transmission. Dengue is a viral disease transmitted mainly by Aedes aegypti mosquitoes and is considered one of the greatest public health problems. The qualitative and quantitative analysis of the spread of this disease is important as it contributes to the design of plans for the prevention of an epidemic. Here, we present the analysis of a metapopulation model of the SIR-SI type representing the dynamics of dengue for two zones connected by the residence times of the human population in each one. Subsequently, we carried out the qualitative analysis of the model considering different connection scenarios between the two areas
The need for scientific communication led by authors and institutions
No full textLa globalización de la ciencia sin duda ha traído muchas ventajas para el desarrollo de la sociedad en áreas como la salud y la tecnología, que no en vano son las áreas de mayor producción científica en el mundo. Sin embargo, el otro lado de la moneda es la invisibilidad de gran cantidad de trabajos científicos que quedan perdidos en el mar de información y conocimiento al que día a día se enfrentan los investigadores y los tomadores de decisiones. ¿Qué se puede hacer? Hacer la ciencia más visible, aprovechando las mismas herramientas utilizadas para identificar “lo que es tendencia”
Morphological characterization of the embryonary stages of the freshwater stingray Potamotrygon magdalenae (Elasmobranchii: Potamotrygonidae)
No full textPotamotrygon magdalenae, una raya perteneciente a la familia Potamotrygonidae distribuida en la cuenca del río Magdalena, es considerada de muy alta prioridad para la investigación en el Plan de Acción Nacional para la Conservación y Manejo de Tiburones, Rayas y Quimeras de Colombia. Los estudios de desarrollo embrionario en condrictios son escasos debido a la dificultad para obtener el material biológico y son pocas las tablas de desarrollo para las especies de rayas. En este estudio se hizo la caracterización morfológica macroscópica de una serie de estadios embrionarios de P. magdalenae. Se obtuvieron 30 individuos entre embriones, fetos y neonatos producto de disecciones y abortos de hembras grávidas capturadas mediante pesca incidental. En términos generales, el desarrollo embrionario de esta especie sigue los patrones conocidos para los demás condrictios, aunque con pequeñas diferencias en la tasa de absorción del saco vitelino y la ausencia de filamentos branquiales sobresalientes de los espiráculos, lo que puede relacionarse con su viviparidad y matrotofia uterina.Potamotrygon magdalenae is a stingray belonging to the family Potamotrygonidae distributed in the Magdalena River basin. This species is considered of high priority for research according to the National Plan of Action for the Conservation and Management of Sharks, Rays, and Chimaeras of Colombia. The studies of embryonic development in chondrichthyans are limited due to the difficulty in obtaining the biological material and there are few developmental staging tables for ray species. Here we do a macroscopic morphological characterization of a series of developmental stages of P. magdalenae. Thirty individuals were studied, including embryos, fetuses, and neonates resulting from dissections and abortions of pregnant females caught by incidental fishing. It was possible to identify nine stages of development that were described, photographed, drawn, and measured. The embryonic development of this species broadly follows the patterns known for other chondrichthyans with minor differences in the rate of yolk sac absorption and the absence of protruding gill filaments from the spiracles, which may be related to its viviparity and intrauterine matrotrophy
Paracoccidioides restrepiensis has undergone a severe population bottleneck
No full textEl género Paracoccidioides hoy abarca cinco especies: P. lutzii, P. brasiliensis sensu stricto, P. americana, P. venezuelensis y P. restrepiensis. Todos los casos de paracoccidioidomicosis reportados en Colombia han sido causados por P. restrepiensis, denominado así en honor de Ángela Restrepo, líder en el estudio de este hongo. Las evaluaciones previas de la diversidad genética han sugerido que las especies de Paracoccidioides difieren en su polimorfismo. Para inferir cambios en el tamaño efectivo de la población, se utilizó el método del coalescente markoviano secuencial por pares (pairwise sequentially Markovian coalescent, PSMC) mediante la generación de dos pseudodiploides para P. restrepiensis y uno para P. brasiliensis sensu stricto. Se encontró que P. restrepiensis divergió de sus especies hermanas recientemente, con un tiempo de divergencia en relación con P. venezuelensis de 125.000 (± 42.000) años. Los análisis que utilizan el PSMC muestran una reducción sistemática en el tamaño efectivo de la población de P. restrepiensis, con una rápida disminución de la variabilidad genética en comparación con P. brasiliensis sensu stricto, lo que indica que P. restrepiensis se ha visto expuesto a un cuello de botella poblacional sistemático. Ninguna de las otras dos especies muestra la drástica reducción efectiva del tamaño de la población observada en P. restrepiensis. Estas comparaciones sugieren que la trayectoria de P. restrepiensis es, de alguna manera, diferente de las otras especies de Paracoccidioides y llevan a preguntarse cuáles han sido los eventos biogeográficos que han producido cambios tan dramáticos en el patrón poblacional.Genus Paracoccidioides now encompasses five species, P. lutzii, P. brasiliensis sensu stricto, P. americana, P. venezuelensis, and P. restrepiensis. All the paracoccidioidomycosis (PCM) cases reported in Colombia have been classified as P. restrepiensis, which was named in honor of Angela Restrepo, a leading researcher in the field of the biology of the fungus. Previous assessments of genetic diversity have suggested that Paracoccidioides species have differences in their level of polymorphism. To infer changes in effective population size, we used the Pairwise sequentially Markovian coalescent (PSMC) by generating two pseudodiploids for P. restrepiensis and one for P. brasiliensis sensu stricto. We found that P. restrepiensis diverged from its sister species recently, the divergence time from P. venezuelensis being 125,000 (± 42,000) years. The analyses using PSMC show a systematic reduction in the effective population size of P. restrepiensis with a rapid decrease in genetic variability compared to P. brasiliensis sensu stricto, which indicates that P. restrepiensis has undergone a systematic population bottleneck. None of the other two species show the dramatic effective population size reduction observed in P. restrepiensis. These comparisons suggest that the trajectory of P. restrepiensis is somehow different from the other Paracoccidioides species and poses the question regarding the biogeographic events that have led to such a dramatic population pattern
Multifunctional nanostructured platform for sequential release of therapeutic molecules
No full textA partir de nanocajas metálicas de doble pared monoporo sintetizadas (DWSPNb) por efecto Kirkendall y reemplazo galvánico, se propone una potencial plataforma multifuncional nanoestructurada con capacidad de liberación secuencial de agentes moleculares para uso terapéutico. Para evaluar la plataforma se realizaron métodos numéricos basados en las dimensiones, morfología y composición de las nanocajas sintetizadas. Para combinaciones de dos moléculas farmacológicas de interés, el
los coeficientes de difusión se determinaron en función de la distancia a las paredes de la nanocaja y de la concentración. La simulación realizada para la liberación de estas dos moléculas de la cavidad interna y el nanocanal formado entre las dos paredes de la nanocaja mostró la cinética secuencial requerida. Este comportamiento permite programar entregas controladas en tiempo y lugar para reducir la resistencia a los fármacos duales y consecuentemente optimizar la dosis necesaria, así como evitar los efectos secundarios derivados. La composición metálica convirtió a la nanocaja en una nanoantena optotérmica que permite el control de la liberación y entrega de la carga a través de polímeros sensibles a la temperatura y, además, su uso potencial para el tratamiento fotodinámico y el diagnóstico por imágenes.From synthesized metallic double-walled single-pore nanoboxes (DWSPNb) by Kirkendall effect and galvanic replacement, a potential nanostructured multifunctional platform with the capacity for sequential release of molecular agents for therapeutic use is proposed. To evaluate the platform, numerical methods based on the dimensions, morphology, and composition of the synthesized nanoboxes were performed. For combinations of two pharmacological molecules of interest, the
diffusion coefficients were determined as a function of the distance to the walls of the nanobox and the concentration. The simulation carried out for the release of these two molecules from the internal cavity and the nanochannel formed between the two walls of the nanobox showed the required sequential kinetics. This behavior allows to schedule controlled deliveries in time and place to reduce resistance to dual drugs and consequently optimize the necessary dose, as well as avoid any derived secondary effects. The metallic composition turned the nanobox into an opto-thermal nanoantenna enabling the control of cargo release and delivery through polymers sensitive to temperature and, additionally, its potential use for photodynamic treatment and diagnostic imaging
Electric vector potential and the Biot-Savart like law in electrostatics
No full textEn este documento se presenta una formulación de potencial vectorial asociado al campo eléctrico para estudiar electrodos de superficie embebidos en un plano. Se muestra que el problema se puede abordar mediante la solución de la ecuación de Laplace en el espacio libre, bajo condiciones de frontera de Neumann sobre las placas cuando la separación entre ellas tiende a cero. Se obtiene que campo eléctrico matemáticamente guarda una analogía con la ley de Biot-Savart de magnetostática. La estrategia permite generalizar dicho resultado analítico para su aplicación en la descripción de electrodos de superficie con separación entre las placas.A vector potential formulation is shown in this article to compute the electric field of planar surface electrodes. The electric field is derived from from the solution of the Laplace’s equation in the free-charge space. Neumann-boundary conditions must be set on the region between planar metallic sheets as the separation goes to zero. It is shown that the electric field can be written via a Biot Savart- like integral. The strategy enables to generalize the analytical result for its application in the gaped surface electrodes description
Nutrient content, acidity and soil texture in areas degraded by mining in the biogeographic Chocó
No full textLa minería es una de las actividades económicas que más destruyen ecosistemas en el Chocó biogeográfico, por lo que se requiere conocer los efectos que esta tiene en las condiciones fisicoquímicas del suelo con miras a su restauración. En ese contexto el objetivo del presente estudio fue evaluar los cambios en las condiciones edáficas de áreas degradadas por la minería a cielo abierto con diferente edad sucesional en la región. Para ello se establecieron cinco parcelas permanentes de 625 y 2.500 m2 en áreas con 15 y 30 años de recuperación, respectivamente. Posteriormente, se tomaron muestras compuestas de suelos a 20 cm de profundidad y se determinaron sus contenidos de nutrientes, pH y textura. Se observó que los suelos eran ácidos (pH=4,73), con altos porcentajes de arena, materia orgánica (6,62 %), nitrógeno (N) total (0,34 %), fósforo (P) disponible (28,21 ppm), potasio (K) (0,38 meq/100g) y aluminio (Al) (2,15 meq/100 g), pero con bajas cantidades de calcio (Ca) (2,28 meq/100 g) y magnesio (Mg) (1,37 meq/100 g). La disponibilidad de P y K fue alta en ambas edades sucesionales, en tanto que la materia orgánica, el N total, el Ca, el Mg, la capacidad de intercambio catiónico efectiva (CICE), el Al, y el porcentaje de arena incrementaron con la sucesión, aunque el pH y la arcilla, disminuyeron. En síntesis, se evidenció un incremento en la disponibilidad de arena y nutrientes, pero también un aumento en la acidez y la toxicidad del Al con la sucesión. Asimismo, se constató que la recuperación de las condiciones fisicoquímicas del suelo en minas está condicionada por el efecto de la materia orgánica y la vegetación.Mining is one of the economic activities that most destroy ecosystems in the biogeographic Chocó, so it is necessary to know the effects it has on the physicochemical conditions of the soil with a view to its restoration. In this context, the objective of this study was to evaluate the changes in the soil conditions of areas degraded by open-cast mining with different successional ages in the region. For this, five permanent plots of 625 and 2,500 m2 were established in areas with 15 and 30 years of recovery, respectively. Subsequently, composite soil samples were taken at a depth of 20 cm and their nutrient content, pH, and texture were determined. It was observed that the soils were acidic (pH=4.73), with high percentages of sand, organic matter (6.62%), total nitrogen (N) (0.34%), available phosphorus (P) (28.21 ppm), potassium (K) (0.38 meq/100g) and aluminum (Al) (2.15 meq/100g), but with low amounts of calcium (Ca) (2 0.28 meq/100 g) and magnesium (Mg) (1.37 meq/100 g). The availability of P and K was high in both successional ages, while organic matter, total N, Ca, Mg, effective cation exchange capacity (ECEC), Al, and percentage of sand increased with succession, although pH and clay decreased. In summary, an increase in the availability of sand and nutrients was evidenced, but also an increase in the acidity and toxicity of Al with the succession. Likewise, it was found that the recovery of the physicochemical conditions of the soil in mines is conditioned by the effect of organic matter and vegetation. 38 meq/100g) and aluminum (Al) (2.15 meq/100 g), but with low amounts of calcium (Ca) (2.28 meq/100 g) and magnesium (Mg) (1.37 meq/100 g). The availability of P and K was high in both successional ages, while organic matter, total N, Ca, Mg, effective cation exchange capacity (ECEC), Al, and percentage of sand increased with succession, although pH and clay decreased. In summary, an increase in the availability of sand and nutrients was evidenced, but also an increase in the acidity and toxicity of Al with the succession. Likewise, it was found that the recovery of the physicochemical conditions of the soil in mines is conditioned by the effect of organic matter and vegetation. 38 meq/100g) and aluminum (Al) (2.15 meq/100 g), but with low amounts of calcium (Ca) (2.28 meq/100 g) and magnesium (Mg) (1.37 meq/100 g). The availability of P and K was high in both successional ages, while organic matter, total N, Ca, Mg, effective cation exchange capacity (ECEC), Al, and percentage of sand increased with succession, although pH and clay decreased. In summary, an increase in the availability of sand and nutrients was evidenced, but also an increase in the acidity and toxicity of Al with the succession. Likewise, it was found that the recovery of the physicochemical conditions of the soil in mines is conditioned by the effect of organic matter and vegetation. 37 meq/100 g). The availability of P and K was high in both successional ages, while organic matter, total N, Ca, Mg, effective cation exchange capacity (ECEC), Al, and percentage of sand increased with succession, although pH and clay decreased. In summary, an increase in the availability of sand and nutrients was evidenced, but also an increase in the acidity and toxicity of Al with the succession. Likewise, it was found that the recovery of the physicochemical conditions of the soil in mines is conditioned by the effect of organic matter and vegetation. 37 meq/100 g). The availability of P and K was high in both successional ages, while organic matter, total N, Ca, Mg, effective cation exchange capacity (ECEC), Al, and percentage of sand increased with succession, although pH and clay decreased. In summary, an increase in the availability of sand and nutrients was evidenced, but also an increase in the acidity and toxicity of Al with the succession. Likewise, it was found that the recovery of the physicochemical conditions of the soil in mines is conditioned by the effect of organic matter and vegetation. and the percentage of sand increased with the succession, although the pH and clay decreased. In summary, an increase in the availability of sand and nutrients was evidenced, but also an increase in the acidity and toxicity of Al with the succession. Likewise, it was found that the recovery of the physicochemical conditions of the soil in mines is conditioned by the effect of organic matter and vegetation. and the percentage of sand increased with the succession, although the pH and clay decreased. In summary, an increase in the availability of sand and nutrients was evidenced, but also an increase in the acidity and toxicity of Al with the succession. Likewise, it was found that the recovery of the physicochemical conditions of the soil in mines is conditioned by the effect of organic matter and vegetation