4,714 research outputs found
Effect of Septoria leaf blotch and its control with commercial fungicides, on arbuscular-mycorrhizal-fungal colonization, spore numbers, and morphotype diversity
Arbuscular-mycorrhizal internal structures (i.e. total root colonization, arbuscules, vesicles) and external structures (i.e. spore density), and Glomeromycota spore morphotypes, were evaluated in wheat severely infected with Mycosphaerella graminicola – the causal agent of Septoria leaf blotch. Plots in which the infection was controlled with a commercial fungicide at recommended field doses, were also examined. The commercial fungicide used was an admixture of trifloxistrobin and tebuconazole. No negative effects of the fungicide application on arbuscular-mycorrhizal fungi (AMF) were found. The M. graminicola fungicidal treatment actually favoured the formation of arbuscules and AMF spores, as there was a selective increase in the density of spores belonging to the glomoid morphotype. Arbuscular-mycorrhizal fungi have an absolute dependence on the carbon provided by the plant. A severe foliar disease leading to a diminished carbon supply to the roots would generate decreases in carbon availability. Such decreases would strongly affect mycorrhizal associations and development. Furthermore, the change in the green-leaf area produced by a severe foliar disease and/or a reversal of that condition through fungicide treatment could result in shifts in the composition of the AMF community so as to favour glomoid morphotypes. Glomoid species have been previously considered as r-strategists.Fil: Schalamuk, Santiago. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Centro de QuÃmica Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de QuÃmica Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Velázquez, MarÃa Silvana. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Centro de QuÃmica Inorgánica "Dr. Pedro J. Aymonino". Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de QuÃmica Inorgánica "Dr. Pedro J. Aymonino"; ArgentinaFil: Simon, Maria Rosa. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones CientÃficas; ArgentinaFil: Cabello, Marta NoemÃ. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botánica Spegazzini; Argentin
Variaciones estacionales y espaciales de la comunidad de larvas de peces de Gran Canaria, Islas Canarias
Temporal and spatial variations of the larval fish community off the island of Gran Canaria (Canary Islands) were studied in weekly surveys from October 2005 to June 2006. A total of 156 taxa, belonging to 51 families and 15 orders, were identified. Myctophidae was by far the most abundant family (30%), followed by Sparidae (11%), Clupeidae (9%) and Gonostomatidae (7%). As expected for an oceanic island, neritic and oceanic taxa contributed in similar proportions. Leeward and windward retention areas were found for total egg and neritic larval abundance. However, seasonality showed a stronger influence on the annual larval assemblage than sampling site, as the latter was not significant on a long time scale. Results suggest that there are two seasonal larval assemblages corresponding to the two main characteristic periods of the water column in these waters: mixing (winter) and stratification (summer). In addition, a significant relationship was recorded between lunar illumination and small mesozooplankton biomass, suggesting that this relationship may be extended to certain neritic families. The most abundant neritic larvae (Sparidae) showed this lunar pattern, which partially supports a recent hypothesis about the effect of lunar illumination on larval fish survival and development in subtropical waters.Se estudiaron las variaciones temporales y espaciales en la comunidad de larvas de peces de la isla de Gran Canaria (Islas Canarias) a partir de muestreos semanales desde octubre 2005 a junio 2006. Se identificaron un total de 156 taxones, pertene- cientes a 51 familias y 15 órdenes. La familia Myctophidae fue la más abundante (30%), seguida por Sparidae (11%), Clupei- dae (9%) y gonostomatidae (7%). Como es de esperar en una isla oceánica, los taxones nerÃticos y oceánicos contribuyeron en proporciones similares. Se encontraron dos zonas de retención para huevos y larvas de especies nerÃticas, a sotavento y barlovento de la isla. Sin embargo, la estacionalidad mostró una mayor influencia en la estructura de la comunidad larvaria que la zona de muestreo, siendo ésta no significativa a largo plazo. Se observaron dos asociaciones estacionales de larvas correspondiendo con los dos perÃodos más caracterÃsticos en la columna de agua: periodo de mezcla (invierno) y de estrati- ficación (verano). además, se encontró una relación significativa entre la iluminación lunar y la biomasa del zooplancton de pequeño tamaño, que podrÃa ser extensible a las larvas nerÃticas. Las larvas nerÃticas más abundantes (Sparidae) mostraron una relación con el ciclo lunar, apoyando parcialmente una hipótesis reciente sobre el efecto de la iluminación lunar en la supervivencia larvaria y su desarrollo en aguas subtropicales
Identifying Unstable Region of Operation in a Micro-grid System
AbstractThis paper presents the stability analysis based on impedance representation of a single phase inverter operating as voltage source, where the Nyquist criteria can be applied. The method can be used to study the stability of a micro-grid dominated by power electronics in isolated operation mode. First, a small signal input impedance model is described. The second methodology applies no energy storage at the AC and DC side of the inverter. For two methods a comparative evaluation with the measured impedance was realized. The obtained results show that the proposed method of no energy storage can be employed in the studies of stability for micro grid systems
A model for providing emotion awareness and feedback using fuzzy logic in online learning
Monitoring users’ emotive states and using that information for providing feedback and scaffolding is crucial. In the learning context, emotions can be used to increase students’ attention as well as to improve memory and reasoning. In this context, tutors should be prepared to create affective learning situations and encourage collaborative knowledge construction as well as identify those students’ feelings which hinder learning process. In this paper, we propose a novel approach to label affective behavior in educational discourse based on fuzzy logic, which enables a human or virtual tutor to capture students’ emotions, make students aware of their own emotions, assess these emotions and provide appropriate affective feedback. To that end, we propose a fuzzy classifier that provides a priori qualitative assessment and fuzzy qualifiers bound to the amounts such as few, regular and many assigned by an affective dictionary to every word. The advantage of the statistical approach is to reduce the classical pollution problem of training and analyzing the scenario using the same dataset. Our approach has been tested in a real online learning environment and proved to have a very positive influence on students’ learning performance.Peer ReviewedPostprint (author's final draft
A fuzzy-based approach for classifying students' emotional states in online collaborative work
(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Emotion awareness is becoming a key aspect in collaborative work at academia, enterprises and organizations that use collaborative group work in their activity. Due to pervasiveness of ICT's, most of collaboration can be performed through communication media channels such as discussion forums, social networks, etc. The emotive state of the users while they carry out their activity such as collaborative learning at Universities or project work at enterprises and organizations influences very much their performance and can actually determine the final learning or project outcome. Therefore, monitoring the users' emotive states and using that information for providing feedback and scaffolding is crucial. To this end, automated analysis over data collected from communication channels is a useful source. In this paper, we propose an approach to process such collected data in order to classify and assess emotional states of involved users and provide them feedback accordingly to their emotive states. In order to achieve this, a fuzzy approach is used to build the emotive classification system, which is fed with data from ANEW dictionary, whose words are bound to emotional weights and these, in turn, are used to map Fuzzy sets in our proposal. The proposed fuzzy-based system has been evaluated using real data from collaborative learning courses in an academic context.Peer ReviewedPostprint (author's final draft
La por en l’aprenentatge motor
La por és una emoció que apareix sovint en situacions d’aprenentatge motor, les conseqüències de la qual poden ser molt negatives. En aquest treball s’analitzen els diferents tipus de por que es poden presentar davant l’execució de determinades tasques motrius i els possibles factors que poden causar-la, tant d’Ãndole interna com externa a la persona que aprèn. Finalment, es proposen un seguit de tècniques o recomanacions, perquè els professors i entrenadors ajudin els alumnes i esportistes a superar la seva por
Fighting the Influenza A virus. New scaffolds and therapeutic targets
Podeu consultar el llibre complet a: http://hdl.handle.net/2445/12071
El factor climático en la erosión del suelo: Erosividad de la lluvia en la cuenca del Ebro
La tesis doctoral ha abordado el estudio de la erosividad de la lluvia en la cuenca del Ebro. Aporta un estudio climatológico detallado sobre las dinámicas espacio-temporales de la erosividad de la lluvia en la cuenca del Ebro, sus tendencias y una relación con parámetros de circulación atmosférica. Aporta además un registro experimental de la erosividad de la lluvia natural
Psychological adaptation to extreme environments: Antarctica as a space analogue
Space analogues are settings where particular conditions can be reproduced to study physiological and psychological variables experienced in space. Antarctica is one of the most reliable analogues to assess the effects of isolation, confinement, light-dark cycle and extreme environmental conditions in human being. In the present review we describe some of the aspects of psychological adaptation to extreme latitudes. Most of the studies found some evidence about changes in emotional states during Antarctica expeditions. However, these changes are highly variable, and beneficial as well as detrimental aspects of adaptation have been described. Adaptation to extreme environments is a complex phenomenon that needs multidimensional studies to be fully understood, comprising aspects such as seasonality, psychological traits, isolation conditions and social interactions.Fil: Tortello, Camila. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Barbarito, Marta. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Cuiuli, Juan Manuel. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Golombek, Diego Andrés. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa. Laboratorio de CronobiologÃa; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Vigo, Daniel Eduardo. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Plano, Santiago Andrés. Universidad Nacional de Quilmes. Departamento de Ciencia y TecnologÃa; Argentina. Pontificia Universidad Católica Argentina "Santa MarÃa de los Buenos Aires". Instituto de Investigaciones Biomédicas. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentin
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