3,913 research outputs found
The center problem for a family of systems of differential equations having a nilpotent singular point
AbstractWe study the analytic system of differential equations in the plane(x˙,y˙)t=∑i=0∞Fq−p+2is, where p,q∈N, p⩽q, s=(n+1)p−q>0, n∈N, and Fi=(Pi,Qi)t are quasi-homogeneous vector fields of type t=(p,q) and degree i, with Fq−p=(y,0)t and Qq−p+2s(1,0)<0. The origin of this system is a nilpotent and monodromic isolated singular point. We prove for this system the existence of a Lyapunov function and we solve theoretically the center problem for such system. Finally, as an application of the theoretical procedure, we characterize the centers of several subfamilies
Protective Yeasts Control V. anguillarum Pathogenicity and Modulate the Innate Immune Response of Challenged Zebrafish (Danio rerio) Larvae
Indexación: Web of ScienceWe investigated mechanisms involved in the protection of zebrafish (Danio rerio) larvae by two probiotic candidate yeasts, Debaryornyces hansenii 97 (Dh97) and Yarrowia Iypolitica 242 (YI242), against a Vibrio anguillarum challenge. We determined the effect of different yeast concentrations (10(4)-10(7) CFU/mL) to: (i) protect larvae from the challenge, (ii) reduce the in vivo pathogen concentration and (iii) modulate the innate immune response of the host. To evaluate the role of zebrafish microbiota in protection, the experiments were performed in conventionally raised and germ free larvae. In vitro co-aggregation assays were performed to determine a direct yeast-pathogen interaction. Results showed that both yeasts significantly increased the survival rate of conventionally raised larvae challenged with V. anguillarum. The concentration of yeasts in larvae tended to increase with yeast inoculum, which was more pronounced for Dh97. Better protection was observed with Dh97 at a concentration of 106 CFU/mL compared to 104 CFU/mL. In germ-free conditions V anguillarum reached higher concentrations in larvae and provoked significantly more mortality than in conventional conditions, revealing the protective role of the host microbiota. Interestingly, yeasts were equally (Dh97) or more effective (YI242) in protecting germ-free than conventionally-raised larvae, showing that protection can be exerted only by yeasts and is not necessarily related to modulation of the host microbiota. Although none of the yeasts co aggregated with V anguillarum, they were able to reduce its proliferation in conventionally raised larvae, reduce initial pathogen concentration in germ-free larvae and prevent the upregulation of key components of the inflammatory/anti-inflammatory response (il1b, tnfa, c3, mpx, and il10, respectively). These results show that protection by yeasts of zebrafish larvae challenged with V anguillarum relates to an in vivo anti-pathogen effect, the modulation of the innate immune system, and suggests that yeasts avoid the host-pathogen interaction through mechanisms independent of co-aggregation. This study shows, for the first time, the protective role of zebrafish microbiota against V. anguillarum infection, and reveals mechanisms involved in protection by two non-Saccharomyces yeasts against this pathogen.http://journal.frontiersin.org/article/10.3389/fcimb.2016.00127/ful
Evaluation of a two-phase extraction system of carbohydrates and proteins from chlorella vulgaris utex 1803
Microalgae are a valuable source of high-value products and biofuels, however the high-energy cost required for the extraction of their metabolites has kept questioning on possible industrial upgrading. The aim of this study was to evaluate the effect of temperature, solvent/biomass, NaOH concentration and thermal pretreatment of the biomass in a 2-cycle carbohydrate and protein extraction system. Results shown that best conditions for carbohydrates extraction are achieved at a solvent concentration of 3.67 M, 55°C and a solvent/biomass ratio of 30mL/g. On the other side, the best conditions for protein were 3 M, 85°C and 45 mL/g. The efficiencies achieved under these conditions were 95% for carbohydrates and 98% for proteins. Using the best extraction conditions for each metabolite a thermal pre-treatment was performed at 25°C, 75°C and 105°C. Results indicate that highest efficiencies were achieved with dry biomass pretreated at 105°C, with values of 95% for carbohydrates and 98% for proteins
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Morphological estimation of Cellularity on Neo-adjuvant treated breast cancer histological images
This paper describes a methodology that extracts morphological features from histological breast cancer images stained for Hematoxilyn and Eosin (H&E). Cellularity was estimated and the correlation between features and the residual tumour size cellularity after a Neo-Adjuvant treatment (NAT) was examined. Images from whole slide imaging (WSI) were processed automatically with traditional computer vision methods to extract twenty two morphological parameters from the nuclei, epithelial region and the global image. The methodology was applied to a set of images from breast cancer under NAT. The data came from the BreastPathQ Cancer Cellularity Challenge 2019, and consisted of 2579 patches of 255×255 pixels of H&E histopatological samples from NAT treatment patients. The methodology automatically implements colour separation, segmentation and morphological analysis using traditional algorithms (K-means grouping, watershed segmentation, Otsu’s binarisation). Linear regression methods were applied to determine strongest correlation between the parameters and the cancer cellularity. The morphological parameters showed correlation with the residual tumour cancer cellularity. The strongest correlations corresponded to the stroma concentration value (r = −0.9786) and value from HSV image colour space (r = −0.9728), both from a global image parameters
The Public and the Cine in Spain. Issues of identity and brand
El cine español ha sufrido una serie de vicisitudes a lo largo de su historia que han marcado tanto su producción, como el desarrollo de una industria solvente y sólida, y la valoración que de la misma ha hecho el público de cada época. Las relaciones que se han establecido entre el ciudadano español en la oferta cinematográfica realizada no han sido las más adecuadas para que la convivencia fuera eficaz. Desde la profesión no se ha hecho el esfuerzo por transmitir una imagen eficaz que pudiera consolidar la marca necesaria para el reconocimiento de la industria. Todas las partes intervinientes en el desarrollo de esta industria han sobrevivido a las novedades sin plantearse seriamente cómo afrontar cada uno de los retos que se le fueron presentando. El resultado no es otro que, en el momento presente, han de involucrarse en recuperar el tiempo perdido si realmente quieren seguir manteniendo activo el negocio. Posibilidades, todavía las hay, pero es necesario el empeño manifiesto de las instituciones, profesionales y público español.Spanish cinema has suffered a series of troubles along its history. They have determined its production, along with the development of a solvent and solid industry. This trajectory has also had influence in the assessment of the audience. The relationships developed between the Spanish audience and the cinema offer haven’t favored their coexistence. From the profession, the effort to transmit an effective image hasn’t achieved to consolidate the necessary branding for the recognition of the industry. All the parts involved in the development of this industry have survived the novelties without seriously consider how to deal with each one of the new challenges. At present, the result is that all those parts involved must join to update the business to keep it active. There are possibilities yet, but a clear determination is needed from the institutions, professionals and the Spanish audience
Pollen morphology of native and cultivated species of Handroanthus (Bignoniaceae) present in Argentina
Morfología polínica de las especies nativas y cultivadas de Handroanthus (Bignoniaceae) de la República Argentina. El objetivo del siguiente trabajo consiste en ampliar el conocimiento palinológico de las especies de Handroanthus (Bignoniaceae) presentes en Argentina e incorporar esta información al Atlas Polínico del NOA que se publica periódicamente on line (www.atlaspolinicodelnoa.com.ar). Se analizaron las siguientes especies: H. albus (Cham.) Mattos, H. chrysotrichus (Mart. ex DC.) Mattos, H. heptaphyllus (Vell.) Mattos, H. impetiginosus (Mart.ex DC.) Mattos, H. lapacho (K. Schum.) Mattos, H. ochraceus (Cham.) Mattos, además de la exótica H. pulcherrimus (Sandwith) S. Grose. El material fue procesado según las técnicas convencionales para acetólisis y polen natural, se tomaron fotos a nivel de microscopía óptica (MO) y microscopía electrónica de barrido (MEB). Los resultados muestran que los granos son medianos de 25 a 31,6 μm en polen natural y de 27,45 a 48 μm en polen acetolizado, suboblatos a subprolatos. Tricolporados (colporoidados) en H. albus, H. chrysotrichus, H. heptaphyllus, H. impetiginosus, H. lapacho y H. pulcherrimus, y 3-colporados (colporoidados), 3-hemisincolporados y loxocolporados en H. ochraceus. La exina es de 1,5 a 2 μm de espesor con la superficie reticulada heterobrocada
Application of principal component analysis to identify pollen subtypes in Miconia (Melastomataceae)
Miconia Ruiz et Pav. es un género característico de regiones selváticas que en Argentina está representado por 10 especies. El objetivo de este trabajo fue la identificación de posibles subtipos polínicos en las especies argentinas de este género señalado como estenopalínico por estudios previos. Se midieron 60 granos de polen de cada una de las especies al microscopio óptico y se realizó un análisis de componentes principales y un árbol de recorrido mínimo, basados en una matríz de especies y variables morfométricas de los granos. Fueron seleccionados dos componentes principales que en conjunto explicaron el 77% de la variación total de los datos. La mayoría de las variables se correlacionaron con el componente 1. Seis especies se definieron en tres subtipos, restando cuatro que no pudieron ser incluidas en ninguno de ellos por presentar caracteres intermedios. Se concluyó que el análisis multivariado constituye una posible herramienta para ayudar a diferenciar subtipos polínicos dentro de géneros estenopalínicos.Miconia Ruiz et Pav. inhabits forest regions being represented in Argentina by 10 species. The aim of this study was to identify possible pollen subtypes in the Argentine species of Miconia. Previous studies found that the genus is stenopalynous. Pollen grains of each species were measured with an optical microscope and a PCA was conducted based on a matrix of species versus morphometric variables of pollen grains. Two components were selected because these explained together 77% of the total variation in the data. Most of the variables were correlated with component 1. Three pollen subtypes were defined in the genus, but four of the species could not be included in any of them because they presented intermediated characters. It was concluded that multivariate analysis is a possible tool that helps to differentiate pollen subtypes within stenopalynous genera.Fil: Ceballos, Sergio Javier. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: García, Maria E.. Fundación Miguel Lillo; ArgentinaFil: Slanis, Alberto C.. Fundación Miguel Lillo; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Reyes, Nora J. F.. Fundación Miguel Lillo; Argentin
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El rubor facial patológico, o ereutofobia, consiste en el sonrojo severo desencadenado por un estímulo social o emocional, debido a una actividad anómala del sistema nervioso simpático. Es uno de los síntomas cardinales de la fobia social; sin embargo, en ocasiones, el propio rubor desencadena la fobia y supone un lastre profesional, psicológico y social para muchas personas.
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¿Cuál es el estilo parental óptimo para adolescentes con baja vs. alta autoeficacia? Autoconcepto, desajuste psicológico y rendimiento académico de los adolescentes en el contexto español
The aim of this paper is to establish which parenting style is associated with optimum outcomes among adolescents of Spanish families considering adolescents with low vs. high self-efficacy. Although classical studies identify the authoritative parenting style (based on warmth and strictness) as the best parental strategy, emerging research seriously questions the benefits of parental strictness. Additionally, the impact of parent-ing on the adolescent’s psychosocial competence has been studied for years, but less is known about whether it might vary depending on individual characteristics of the adolescent (e.g., self-efficacy). Participants were 1029 Spanish adolescents, 453 males (44%), aged 12-17 years. Families were classified in one of the parenting styles groups (authoritative, authoritarian, indulgent, or neglectful), and adolescents were grouped by low vs. high self-efficacy. Adolescent psychosocial competence was examined through emotional and academic self-concept, psychological maladjustment (hostility/aggression, negative self-esteem, emotional responsivity, instability, and negative view of the world), and academic performance (grade point average and number of failing grades). Main and interaction effects of parenting style and adolescent self-efficacy were tested. Main effect results indicated that adolescents with low self-efficacy were always as-sociated with the worst psychosocial competence. Consistently, the main effect findings indicated that adolescents from indulgent and authoritative families were associated with better results than those from neglectful and authoritarian families. However, the indulgent parenting style yielded the best results. The impact of parenting might not be the same for adolescents in all cultural contexts. Contrary to findings from classical studies, parental strictness seems to be unnecessary or even detrimental for adolescents with low and high self-efficacy.El objetivo de este estudio es identificar qué estilo parental se asocia con resultados óptimos entre los adolescentes de familias españolas considerando aquellos con baja vs. alta autoeficacia. Los participantes fue-ron 1029 adolescentes españoles, 453 varones (44%), de 12 a 17 años. Aunque los estudios clásicos identifican el estilo autorizativo (basado en el afecto y la severidad)como la mejor estrategia socializadora, las investigaciones emergentes cuestionan seriamente los beneficios de la severidad parental. Además, el impacto de la socialización parental en la competencia psicosocial del adolescente se ha estudiado durante años, pero se sabe me-nos sobre si podría variar en función de las características individuales del adolescente (e.g., la autoeficacia). Las familias fueron clasificadas por estilo parental (autorizativo, autoritario, indulgente o negligente), y los adolescentes por baja vs. alta autoeficacia. La competencia psicosocial se examinó a través del autoconcepto emocional y académico, el desajuste psicológico (hostilidad/agresión, autoestima negativa, irresponsividad emocional, inestabilidad emocional y visión negativa del mundo) y el rendimiento académico (nota media y número de cursos repetidos). Se comprobaron los efectos principales y de interacción de estilo parental y autoeficacia. Los resultados de los efectos principales indicaron que los adolescentes con baja autoeficacia presentaban siempre la peor competencia psicosocial. También que los adolescentes de familias indulgentes y autorizativas presentaron mejores resultados que los de familias negligentes y autoritarias. Sin embargo, el estilo parental indulgente se asoció a los mejores resultados. El impacto de la socialización parental podría no ser igual en todos los contextos culturales. Frente a los resultados de los estudios clásicos, la severidad parental parece ser innecesaria o incluso perjudicial para los adolescentes con baja y alta autoeficacia
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