Emergence of spike correlations in periodically forced excitable systems

In sensory neurons the presence of noise can facilitate the detection of weak information-carrying signals, which are encoded and transmitted via correlated sequences of spikes. Here we investigate relative temporal order in spike sequences induced by a subthreshold periodic input, in the presence of white Gaussian noise. To simulate the spikes, we use the FitzHugh-Nagumo model, and to investigate the output sequence of inter-spike intervals (ISIs), we use the symbolic method of ordinal analysis. We find different types of relative temporal order, in the form of preferred ordinal patterns which depend on both, the strength of the noise and the period of the input signal. We also demonstrate a resonance-like behavior, as certain periods and noise levels enhance temporal ordering in the ISI sequence, maximizing the probability of the preferred patterns. Our findings could be relevant for understanding the mechanisms underlying temporal coding, by which single sensory neurons represent in spike sequences the information about weak periodic stimuli

The effects of a background potential in star cluster evolution: a delay in the relaxation time-scale and runaway collision processes

Runaway stellar collisions in dense star clusters are invoked to explain the presence of very massive stars or blue stragglers in the center of those systems. This process has also been explored for the first star clusters in the Universe and shown to yield stars that may collapse at some points into an intermediate mass black hole. Although the early evolution of star clusters requires the explicit modeling of the gas out of which the stars form, these calculations would be extremely time-consuming and often the effects of the gas can be accurately treated by including a background potential to account for the extra gravitational force. We apply this approximation to model the early evolution of the first dense star clusters formed in the Universe by performing $N$-body simulations, our goal is to understand how the additional gravitational force affects the growth of a very massive star through stellar mergers in the central parts of the star cluster. Our results show that the background potential increases the velocities of the stars, causing an overall delay in the evolution of the clusters and in the runaway growth of a massive star at the center. The population of binary stars is lower due to the increased kinetic energy of the stars, initially reducing the number of stellar collisions, and we show that relaxation processes are also affected. Despite these effects, the external potential enhances the mass of the merger product by a factor $\sim$2 if the collisions are maintained for long times.Comment: 16 pages. Accepted for publication in Astronomy and Astrophysic

Sorbed Anthracene Degradation by Sophorolipid Producing Yeasts

The organic pollutan adsorption/desorption process by microbial degradation had been less studied than metal ones. The sorption assays alone did not predict desorption, due to hysteresis, irreversibility, fixed compounds in different sites, with diverse desorption rates. Most of the studies dealt with bacteria rather than filamentous fungi and yeasts. So, our aims were to isolate yeasts from polluted sediments, to quantify its potential to uptake anthracene (An) and to evaluate the bioavailability by a desorption model. Yeasts were isolated from hydrocarbon-polluted samples, 40-isolates grew in anthracene-plates. Molecular characterization was achieved by sequence analysis of the ITS1-5.8S rRNA-ITS4 and 26S rRNA regions; morphological and physiological determination were also done. Candida parasilopsis, Pichia anomala and Rhodothorula mucilaginosa were the prevalent yeasts. An-degradation was assessed in soil-systems with 0, 50, 100, 150, 200 and 250 µg An/l, 3 differentes sorbens types, organic carbon, organic nitrogen, PAHs, sand:silt:clay, pH and cation exchange capacity. Sophorolipids excretion were confirmed by HPLC, UV-detector with active fraction at 9.669 min (RT 9.646 min = sophorolipid-standard). A desorption model with equilibrium, nonequilibrium and nondesorption areas, was applied to explain the experimental data, An-transformation was greater in the organic liquid-phase than in the soil-sorbed ones; the desorption-coefficients and soil components were negatively correlated with the kinetic parameters. The An-release depended on the sophorolipid excretion, soil matrix and particles sizes. Desorption parameters significantly fitted the yeast uptake, with R2 = 0.97, R2 = 0.90 and R2 = 0.97 for C. parasilopsis, P. anomala and R. mucilaginosa, respectively

Genetic patterns of Streptococcus uberis isolated from bovine mastitis

The aim of this study was to evaluate the genotypic relationships among 40 Streptococcus uberis isolated from bovine mastitis by using pulsed-field gel electrophoresis (PFGE). Additionally, the association between PFGE patterns and virulence profiles was investigated. The isolates exhibited 17 PFGE patterns. Different strains were found within and among herds; however, a low number of isolates within the same herd shared an identical PFGE type. No association between PFGE patterns and virulence profiles was found. However, the detection of specific strains in some herds could indicate that some strains are more virulent than others. Further research needs to be undertaken to elucidate new virulence-associated genes that might contribute to the capability of these strains to produce infection.El objetivo del presente estudio fue evaluar las relaciones genotípicas entre 40 Streptococcus uberis aislados de mastitis bovina mediante la técnica de electroforesis de campos pulsantes (pulsed-field gel electrophoresis [PFGE]). Además, se investigó la asociación entre los patrones de PFGE y los perfiles de virulencia. Los aislamientos mostraron 17 patrones de PFGE. Se encontraron diferentes cepas dentro de los tambos y en los distintos tambos, y un bajo número de aislamientos dentro del mismo tambo compartieron un perfil idéntico de PFGE. No se encontró ninguna asociación entre los patrones de PFGE y los perfiles de virulencia. Sin embargo, la detección de cepas particulares en algunos tambos podría indicar que algunas de ellas son más virulentas que otras. Sería importante avanzar en las investigaciones para identificar nuevos genes relacionados con la virulencia que podrían contribuir a la capacidad infecciosa de estas cepas.Fil: Reinoso, Elina Beatríz. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lasagno, Mirta C.. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales; ArgentinaFil: Odierno, Liliana M.. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales; Argentin

El Agroturismo como una alternativa micro empresarial en el cantón Puerto Quito, recinto Tatalá

El propósito principal de esta investigación, es conocer la situación actual de la industria turística en el Cantón Puerto Quito y realizar el diagnóstico del potencial agroturístico del recinto Tatalá; para ello es propicio realizar una conceptualización y diferenciación de los diferentes tipos de productos turísticos para evitar confusiones y rescatar el concepto que mejor se adapta a la realidad de este caso, el mismo que se detalla en el capítulo I. El método lógico utilizado es el Inductivo - descriptivo, con éste método se analizan casos particulares a partir de los cuales se extraen conclusiones de carácter general. En el capítulo II se realiza el diagnóstico del sector el que tiene por objeto conocer y describir la situación real de los finqueros y de Puerto Quito. Incluye además, la identificación de actores principales instituciones públicas y privadas, personas naturales que intervienen en el desarrollo de las actividades turísticas ( dueños de tierras, gobierno cantonal, asociaciones), usando las siguientes técnicas de investigación: entrevistas personales a empresarios turísticos del sector, grupos focales a funcionarios de la Alcaldía de Puerto Quito, revisión de información bibliográfica en la Alcaldía En el capítulo III se realiza el mapeo de recursos turísticos de la zona: clasificación de los entornos naturales de acuerdo a su potencialidad turística realizando visitas in situ al sector, entrevistas y encuestas a los habitantes del sector e investigación en entidades públicas y privadas. En el capítulo IV se diseña un cuadro de estrategias para potenciar el agroturismo en el recinto Tatalá y finalmente el capítulo V muestra las principales conclusiones y recomendaciones de la investigación

Global instability by runaway collisions in nuclear stellar clusters: Numerical tests of a route for massive black hole formation

The centers of galaxies host nuclear stellar clusters, supermassive black holes, or both, but the origin of this dichotomy is still a mystery. Nuclear stellar clusters are the densest stellar system of the Universe, so they are ideal places for runaway collisions to occur. In these dense clusters it is possible that global instability occurs, triggered by collisions and mergers forming a massive black hole. Here we test a new mechanism to form massive black holes through runaway stellar collisions in nuclear stellar clusters, performing N-body simulations using the code nbody6++gpu. Our idealized models show that there is a critical mass where collisions become very efficient making it possible to form massive black holes in nuclear stellar clusters. The most massive objects reach masses of the order of $10^4-10^5\rm~ M_\odot$. We find that our highest black hole formation efficiency is up to $50\%$ of the stellar mass at the end of the simulation. In real astrophysical systems, the critical mass scale for this transition is expected to occur in stellar clusters of $10^7-10^9\rm~M_\odot$, implying the formation of quite massive central objects.Comment: 11 pages, 6 figure

Weather radar for urban hydrological applications: lessons learnt and research needs identified from 4 pilot catchments in North-West Europe

International audienceThis study investigates the impact of rainfall estimates of different spatial resolutions on the hydraulic outputs of the models of four of the EU RainGain project’s pilot locations (the Cranbrook catchment (UK), the Herent catchment (Belgium), the Morée-Sausset catchment (France) and the Kralingen District (The Netherlands)). Two storm events, one convective and one stratiform, measured by a polarimetric X-band radar located in Cabauw (The Netherlands) were selected for analysis. The original radar estimates, at 100 m and 1 min resolutions, were aggregated to a spatial resolution of 1000 m. These estimates were then applied to the high-resolution semi-distributed hydraulic models of the four urban catchments, all of which have similar size (between 5 and 8 km2), but different morphological, hydrological and hydraulic characteristics. When doing so, methodologies for standardising rainfall inputs and making results comparable were implemented. The response of the different catchments to rainfall inputs of varying spatial resolution is analysed in the light of model configuration, catchment and storm characteristics. Rather surprisingly, the results show that for the two events under consideration the spatial resolution (i.e. 100 m vs 1000 m) of rainfall inputs does not have a significant influence on the outputs of urban drainage models. The present study will soon be extended to more storms as well as model structures and resolutions, with the final aim of identifying critical spatial-temporal resolutions for urban catchment modelling in relation to catchment and storm event characteristics

Near-realtime quantitative precipitation estimation and prediction (RealPEP)

Flash floods in small- to medium-sized catchments and intense precipitation over cities caused by severe local storms pose increasing threats to our society. For the timely prediction of such events, the value of high-resolution and high-quality QPE and corresponding forecasts cannot be overrated. Seamless predictions harmonizing nowcasting and numerical weather prediction (NWP) across forecast lead times from minutes to days would greatly help to improve the value and efficiency of warnings. Organized by the Research Unit on Near-Realtime Precipitation Estimation and Prediction (RealPEP, www2.meteo.uni-bonn.de/realpep) and supported by the Project on Seamless Integrated Forecasting System (SINFONY, www.dwd .de/DE/forschung/forschungsprogramme/sinfony_iafe/sinfony_node.html) of the German Meteorological Service (DWD), an international 3-day online conference was held from 5 to 7 October 2020, dedicated to Precipitation and Flash-Flood Predictions from Minutes to Days (https://indico .scc.kit.edu/event/883/). Most speakers agreed to have their presentations recorded, which we uploaded to YouTube for further distribution (see, e.g., on the conference homepage, https:// indico.scc.kit.edu/event/883/page/588-recorded-talks). The speakers were both invited experts in the respective research fields and researchers from the RealPEP and SINFONY projects. Talks and discussions could be followed on video stream. Interaction between the about 250 participants was enabled by entering written questions and comments via a dedicated tool, which allowed for voting and thus also ranking questions. Registered participants could enter chat rooms from where they could be moved to the speaker room for posing the questions directly to the speakers and the auditorium. On the last day of the conference podium discussions with selected speakers summarized talks and discussions and elaborated on overarching problems, ideas, and developments in the fields of quantitative precipitation estimation (QPE), quantitative precipitation nowcasting (QPN), quantitative precipitation forecasting (QPF), flash-flood prediction (FFP), and their organization into seamless prediction systems, which also constituted the topics of the five sessions during the conference. We report here in particular on the outcomes of the panel discussions

INCIDENCIA DE CARDIOPATÍAS DURANTE EL EMBARAZO EN LA PROVINCIA DE VILLA CLARA / Incidence of heart disease during pregnancy in Villa Clara province

ResumenIntroducción y objetivos: Las enfermedades cardiovasculares constituyen la cuarta causa de muerte durante el período gravídico-puerperal, y un indicador de morbilidad y mortalidad para el producto de la concepción. El objetivo de esta investigación fue determinar el comportamiento de la cardiopatía en la embarazada, su atención médica y evolución durante y al final del embarazo. Método: Se realizó un estudio descriptivo, prospectivo, donde se analizaron 283 gestantes con diagnóstico de cardiopatía, atendidas en el Hospital Universitario Gineco-Obstétrico "Mariana Grajales" de Santa Clara, Villa Clara, en el período 2008-2010. La información se obtuvo mediante la revisión de las historias clínicas individuales, interrogatorio, examen físico completo, así como pruebas complementarias para establecer o confirmar el diagnóstico. Resultados: Se obtuvo una incidencia de 17,2 cardiopatías por cada mil gestantes y en el 59,7 % de ellas, la cardiopatía era adquirida; el prolapso valvular mitral fue la más frecuente (45 %). De las congénitas, el 36,8 % se trataba de una comunicación interauricular. Se utilizó antibioprofilaxis en el 96,8 % de las embarazadas y en el 96,1 % de ellas se mantuvo un seguimiento médico. El 92,6 % tenía clase funcional I y 4,6 % presentó complicación por su enfermedad. El 77,4 % parió entre las 37 y 42 semanas, y el 82,7 % tuvo parto eutócico. Conclusiones: Las gestantes cardiópatas fueron más frecuentes en edades entre 20 y 29 años, con predominio de las que no habían parido, captación entre las 13 y 24 semanas, y cardiopatías adquiridas. La atención médica que prevaleció fue la antibioprofilaxis y el seguimiento médico con evolución final del embarazo satisfactoria. / AbstractIntroduction and Objectives: Cardiovascular diseases are the fourth leading cause of death during the gravid-puerperal period, and an indicator of morbidity and mortality for the product of conception. The objective of this research was to determine the behavior of heart disease in pregnant women, its medical care and evolution during and after pregnancy. Method: A prospective descriptive study was performed, which analyzed 283 pregnant women diagnosed with heart disease, and treated at the Obstetrics and Gynecology University Hospital "Mariana Grajales" in Santa Clara, Villa Clara, in the period 2008-2010. Information was obtained through review of individual medical records, interview, complete physical examination and laboratory tests to establish or confirm the diagnosis. Results: A heart disease incidence of 17.2 per thousand pregnant women was obtained and in 59.7% of them, the heart disease was acquired, and the mitral valve prolapse was the most frequent (45%). Of the congenital diseases, 36.8% was an atrial septal defect. Antibiotic prophylaxis was used in 96.8% of pregnant women and in 96.1% of them a medical monitoring was kept. 92.6% had functional class I and 4.6% presented disease-related complications. 77.4% gave birth between 37 and 42 weeks, and 82.7% had vaginal delivery. Conclusions: Pregnant women with heart disease were more common in ages 20 to 29 years, predominantly in those who had not given birth, whose pregnancies had been detected between 13 and 24 weeks, and with acquired heart diseases. The prevailing medical care was antibiotic prophylaxis and medical monitoring with satisfactory final outcome of pregnancy