El color de las flores de Nicotiana Glauca y su percepción a través de la mirada de los diferentes polinizadores en poblaciones nativas e introducidas

55 h. + Anexos. ils. col.; figuras; Contiene Referencia Bibliográfica.La identidad y abundancia de los polinizadores puede variar significativamente entre rangos de distribución nativos y no-nativos. Diferentes polinizadores muestran distintas habilidades visuales y cognitivas que pueden influir en la evolución del color floral. Nicotiana glauca (Solanaceae) es una planta Sudamericana polinizada por picaflores que se ha convertido en una importante invasora de áreas semiáridas del mundo, donde es visitada por animales locales, como aves de la familia Nectariniidae en Sudáfrica o esfíngidos diurnos en España. Además, abejorros de la especie Xylocopa ordinaria actúan como ladrones de néctar en el rango nativo. En esta Tesina, se midió el espectro de reflectancia de la corola en un total de 541 individuos de esta especie pertenecientes a tres poblaciones nativas y cuatro poblaciones introducidas que abarcan los diferentes contextos de polinización. Para determinar cómo es percibida la coloración de las flores de dichas poblaciones por los distintos visitantes florales presentes en las regiones estudiadas, los loci de color floral fueron representados en el espacio visual de aves tetracromáticas: nectarínidos y picaflores sensibles a la longitud de onda ultravioleta (UV) y picaflores sensibles al violeta (V), esfíngidos y abejorros tricromáticos. Mediante contrastes cromáticos y acromáticos, se evaluó si los distintos visitantes florales discriminarían el color de la corola de las poblaciones de los diferentes contextos. Además, se indagó si el color rojo para el ojo humano presente de algunas flores en el rango nativo podría haber evolucionado para evitar a los abejorros ladrones de néctar. Para ello, se clasificaron las flores de las poblaciones nativas en cuatro categorías de color (rojas y amarillas que absorben o reflejan UV) de manera objetiva mediante un Análisis de Componentes Principales (ACP), y se compararon los contrastes cromáticos y acromáticos entre pares de categorías para los sistemas de visión de picaflores y abejorros. Se encontró una variación significativa en el espectro de reflexión de la corola tanto entre contextos de polinización como entre poblaciones dentro de cada contexto, especialmente en el área de distribución nativa. Desde el punto de vista de los polinizadores (picaflores, nectarínidos y esfíngidos), las flores de las poblaciones nativas fueron, en general, significativamente discriminadas de las de las poblaciones no nativas, que en su mayoría no fueron discriminadas como diferentes entre sí. En cuanto a la conspicuidad de las flores de diferentes colores en el rango nativo, se encontró que más que el color rojo vs el amarillo, es la reflexión en el rango UV tanto en flores rojas (en mayor proporción) como amarillas lo que las hace indistinguibles del fondo verde de las hojas de N. glauca tanto para los abejorros como para los picaflores. Por otra parte, mientras las flores que reflejan UV serían distinguidas de las flores que absorben por ambos grupos de visitantes florales, las flores rojas y amarillas que reflejan UV no serían distinguidas entre sí por los abejorros. Estos hallazgos se discuten bajo la hipótesis de la selección de color mediada por polinizadores y por ladrones de néctar, como también en relación a procesos evolutivos alternativos, como la deriva génica, que pueden ocurrir durante las invasiones, y a factores abióticos como posibles modeladores del color floral.Fil: Costa, Antonella. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Laboratorio de Ecología Evolutiva y Biología Floral; Argentina.Fil: Costa, Antonella. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina

BWR Instability Analysis by Coupled 3D Neutron-Kinetic and Thermal-Hydraulic Codes

The main aim of this thesis is to contribute to the study of the Boiling Water Reactor (BWR) instability phenomena. The RELAP5-MOD3.3 thermal-hydraulic system code and the PARCS-2.4, 3D neutron kinetic code, were coupled to simulate BWR transients. Different algorithms were used to calculate the decay ratio (DR) and the natural frequency (NF) from the power oscillation signals obtained from the transient calculations, as two typical parameters used to provide a quantitative description of instabilities. The validation of a code model set up for the Peach Bottom-2 BWR plant is performed against Low-Flow Stability Tests (LFST). The thesis has the following organisation. Chapter 1 deals with general aspects, starting with the present level of the Light Water Reactor (LWR) development, addressing the specific problem of instability in BWRs and finally analysing the issue of the current tools to investigate the phenomenon. Chapter 2 describes the LFST performed in the Peach Bottom BWR, the perturbations events studied and the methodology adopted to perform them. Chapter 3 presents the codes and the methodology utilized to perform the calculations and the analyses of the events. In Chapter 4, results considering steady state and transient reactor conditions will be presented and discussed. Finally, Chapter 5 describes the obtained conclusions and the contributions of this work to study of BWR stability

Analyses of instability events in the Peach Bottom-2 BWR using thermal-hydraulic and 3D neutron kinetic coupled codes technique

Boiling water reactor (BWR) instabilities may occur when, starting from a stable operating condition, changes in system parameters bring the reactor towards an unstable region. In order to design more stable and safer core configurations, experimental and theoretical studies about BWR stability have been performed to characterise the phenomenon and to predict the conditions for its occurrence. In this work, contributions to the study of BWR instability phenomena are presented. The RELAP5/MOD3.3 thermal-hydraulic (TH) system code and the PARCS-2.4 3D neutron kinetic (NK) code were coupled to simulate BWR transients. Different algorithms were used to calculate the decay ratio (DR) and the natural frequency (NF) from the power oscillation predicted by the transient calculations as two typical parameters used to provide a quantitative description of instabilities. The validation of the code model set up for the Peach Bottom Unit 2 BWR plant is performed against low-flow stability tests (LFSTs). The four series of LFST have been performed during the first quarter of 1977 at the end of cycle 2 in Pennsylvania. The tests were intended to measure the reactor core stability margins at the limiting conditions used in design and safety analyses

Estudio de hormigones y morteros aligerados con agregados de plástico reciclado como árido y carga en la mezcla

El objetivo de la investigación desarrollada es utilizar gránulos de plástico reciclado como agregado en la mezcla de morteros en sustitución de una fracción de áridos o agregados naturales. Se reduce la densidad del mortero con el consiguiente aumento del aislamiento térmico y al mismo tiempo se da un nuevo uso al PVC reciclado. La investigación estudia diferentes dosificaciones y determina las características mecánicas y térmicas de cada una de ellas

Self-Rated Health and Psychological Distress among Emerging Adults in Italy: A Comparison between Data on University Students, Young Workers and Working Students Collected through the 2005 and 2013 National Health Surveys

Background. The present study aimed at comparing self-reported physical health and mental health among university students, workers, and working students aged between 19 years and 29 years. Method. Using data from National Health Surveys held in 2005 and 2013, a cross-sectional study was conducted on 18,612 Italian emerging adults grouped into three groups: university students, workers, and working students. The odds ratios of self-reported anxiety or depression, poor general health, and poor mental health and physical health (as assessed through SF-12) were estimated through logistic regression models adjusted for potential confounders. Results. Compared with workers, students showed an increased risk of anxiety or depression and a lower risk of poor general health. Students and working students showed an increased risk of reporting weak mental health compared with that in workers, while students displayed a lower risk of poor physical health. Significant differences were not found between the 2005 and 2013 surveys. Conclusions. These results are of considerable importance for psychologists as well as educational and occupation-based institutions for planning prevention programs and clinical interventions

ARMONIA Project: Transfrontier Strategy in the Management of Earthquakes

The ARMONIA project between Italy and Austria, represents a cross-border strategy for prevention and management of seismic risk through real-time production of shaking and damage scenarios using integration and processing of data from seismic and accelerometer monitoring networks. Partners are developing an innovative seismic monitoring system to have an immediate evaluation of the damages distribution and to plan interventions immediately after the occurrence of a destructive earthquake. The first year of ARMONIA project was focused on the reinforcement and improvement of cross border existing free-field accelerometric network and implementation of a dense monitoring network of "significant" buildings through the creation of a dense monitoring network of sensible target buildings in near fault high risk areas along the cross-border territory between Italy and Austria. New instrumentation has been tested and new sites have been selected by following common protocols. This allows to enhance the effectiveness in a transnational prospective, in order to obtain the required quality of the data together with the maximum distribution of the instruments in the territory and provides high level of efficiency adding important information in case of emergency

Structural Parameters of Seven SMC Intermediate-Age and Old Star Clusters

We present structural parameters for the seven intermediate-age and old star clusters NGC121, Lindsay 1, Kron 3, NGC339, NGC416, Lindsay 38, and NGC419 in the Small Magellanic Cloud. We fit King profiles and Elson, Fall, and Freeman profiles to both surface-brightness and star count data taken with the Advanced Camera for Surveys aboard the Hubble Space Telescope. Clusters older than 1 Gyr show a spread in cluster core radii that increases with age, while the youngest clusters have relatively compact cores. No evidence for post core collapse clusters was found. We find no correlation between core radius and distance from the SMC center, although consistent with other studies of dwarf galaxies, some relatively old and massive clusters have low densities. The oldest SMC star cluster, the only globular NGC121, is the most elliptical object of the studied clusters. No correlation is seen between ellipticity and distance from the SMC center. The structures of these massive intermediate-age (1-8 Gyr) SMC star clusters thus appear to primarily result from internal evolutionary processes.Comment: 16 pages, 13 figure