Inability of the brown citrus aphid (Toxoptera citricida) to transmit citrus psorosis virus under controlled conditions

Might Toxoptera citricida (BrCA) be a citrus psorosis virus (CPsV) vector? We examined CPsV transmission by the BrCA throughout two experiments. In experiment 1, 4 CPsV-infected plants bearing BrCA colonies were introduced in separated cages with 12 healthy 'Madame Vinous' sweet orange (MV) seedlings in each one (48 in total). In experiment 2, 5 BrCAs collected from each CPsV-infected plant were transferred into 3 MV seedlings for each one (12 in total) and left for a 72-h inoculation period. Both experiments were replicated once. No psorosis symptoms or CPsV detection evidences a BrCA inability for CPsV transmission under our controlled conditions.

Low X-Ray Luminosity Galaxy Clusters. II. Optical properties and morphological content at 0.18 < z < 0.70

This is the second of a series of papers on low X-ray luminosity galaxy clusters, in which we present the $r^\prime$, $g^\prime$ and $i^\prime$ photometry obtained with GMOS-IMAGE at Gemini North and South telescopes for seven systems in the redshift range of 0.18 to 0.70. Optical magnitudes, colours and morphological parameters, namely, concentration index, ellipticity and visual morphological classification, are also given. At lower redshifts, the presence of a well-defined red cluster sequence extending by more than 4 magnitudes showed that these intermediate-mass clusters had reached a relaxed stage. This was confirmed by the small fraction of blue galaxy members observed in the central regions of $\sim$ 0.75 Mpc. In contrast, galaxy clusters at higher redshifts had a less important red cluster sequence. We also found that the galaxy radial density profiles in these clusters were well fitted by a single power law. At 0.18 $<$ z $<$ 0.70, we observed an increasing fraction of blue galaxies and a decreasing fraction of lenticulars, with the early-type fraction remaining almost constant. Overall, the results of these intermediate-mass clusters are in agreement with those for high mass clusters.Comment: 16 pages, 13 figures, 5 tables. Accepted for publication in MNRA

Short-term effects of different techniques to prepare an organic citrus soil for replanting on its microbiological and biochemical properties

Adopting measures to increment soil levels of organic matter and biological activity is key when an agrosystem is going to be converted to organic management. Nutrient reserves are increased and more easily mobilized, and soil suppresivity is enhanced. This last aspect is particularly relevant in replantations where chemical disinfection treatments can not be used and plantlets are very sensitive. A field trial is therefore being carried out to study the effects on soil biochemical and microbiological properties of different techniques(disinfectant vegetal cover, organic amendment and biofumigation, with untreated and solarized controls) to prepare the soil for replanting in a citrus orchard in convertion to organic management. This work discusses the results obtained six months after the application of all treatments was finished. The effects of the treatments on the soil biochemical parameters were consistent with those found immediately after the treatments were applied, showing a clear depressive effect of solarization on all parameters but chitinase. On the other hand, microbiological parameters were very variable and the changes observed after the treatments had disappeared

A new massive double-lined spectroscopic binary system: The Wolf-Rayet star WR68a

Double-lined spectroscopic binary systems, containing a Wolf-Rayet and a massive O-type star, are key objects for the study of massive star evolution because these kinds of systems allow the determination of fundamental astrophysical parameters of their components. We have performed spectroscopic observations of the star WR 68a as part of a dedicated monitoring program of WR stars to discover new binary systems. We identified spectral lines of the two components of the system and disentangled the spectra. We measured the radial velocities in the separated spectra and determined the orbital solution. We discovered that WR 68a is a double-lined spectroscopic binary with an orbital period of 5.2207 days, very small or null eccentricity, and inclination ranging between 75 and 85 deg. We classified the binary components as WN6 and O5.5-6. The WN star is less massive than the O-type star with minimum masses of 15 ± 5 M⊙ and 30 ± 4 M⊙, respectively. The equivalent width of the He ii λ4686 emission line shows variations with the orbital phase, presenting a minimum when the WN star is in front of the system. The light curve constructed from available photometric data presents minima in both conjunctions of the system.Fil: Collado, Ana Elisa. Consejo Nacional de Investigaciones Cienti­ficas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales; ArgentinaFil: Gamen, Roberto Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Astrofísica de La Plata; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Barba, Rodolfo Hector. Universidad de la Serena; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Morrell, Nidia Irene. Carnegie Observatories; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Hábitos de consumo de drogas y percepción sobre los efectos en salud y rendimiento académico en estudiantes de Psicología en la Universidad de Huelva

El objetivo del trabajo es describir las prevalencias y las relaciones entre las diferentes drogas en estudiantes universitarios. Además conocer la percepción que tienen los estudiantes sobre los efectos de las drogas en el rendimiento académico y en la salud. La muestra está compuesta por 153 estudiantes de psicología de la Universidad de Huelva. Los datos de consumo y percepción se recogen mediante un cuestionario, anónimo y voluntario. Nuestros resultados ponen de manifi esto que las sustancias más consumidas y de inicio más temprano son el alcohol, el tabaco y el cannabis, por tanto, se confi rman las tendencias encontradas en jóvenes. Del mismo modo, se confi rma el patrón de policonsumo en un 60,78% de la muestra. El consumo de tabaco se inicia antes que el del alcohol o cannabis, y cuanto antes se inicia en el consumo de tabaco, antes también se inicia en el consumo de otras sustancias. Según sean las sustancias combinadas, se hallan diferencias en la edad de inicio del alcohol y en la cantidad de cigarrillos de tabaco. Se comienza a consumir alcohol antes si los que beben también fuman. Los que fuman más cigarros son los que combinan el tabaco con alguna otra droga ilegal distinta al cannabis. Con respecto a la percepción sobre el efecto del consumo de drogas, aquellos que consumen alcohol, tabaco y cannabis, consideran que las drogas afectan menos al rendimiento académico que los no consumidores o consumidores de drogas legales.The aim of this study is to describe the prevalence and relationships between different drugs among college students, as well as getting to know the perception of students about the effects of drugs on academic performance and health. The sample consists of 153 psychology students from the University of Huelva. The consumption and perception data are collected by an anonymous and voluntary questionnaire. Our results show that the most widely-consumed substances with earliest onset are alcohol, tobacco and cannabis, thus confi rming the trends found in young people. Similarly, polyconsumption is confi rmed with a percentage of 60.78% of the sample. Tobacco consumption starts earlier than alcohol or cannabis, and the sooner people start to consume tobacco, the sooner the consumption of other substances starts. Depending on the substances combined, there are differences in the age of onset of alcohol and the quantity of tobacco cigarettes. Thus, if those who drink also smoke, the age of onset of alcohol use is earlier. Those who smoke most cigarettes are the ones who combine tobacco with any illegal drug other than cannabis. With regard to perception of the effect of drug use, students who use alcohol, cannabis and tobacco consider that drugs affect academic performance less than non-users or consumers of legal drugs

Major and minor mergers: global star formation efficiency

Se realizó un análisis de interacciones mayores y menores seleccionadas a partir del catálogo espectroscópico Sloan Digital Sky Survey (SDSSDR7). Se construyó una muestra de galaxias en pares cercanos aplicando el límite de separaciones proyectadas, rp By visual inspection of SDSS images we removed false identifications and we classify the interactions into three categories: pairs undergoing merging, M; pairs with evident tidal features, T; and non disturbed, N.We also divide the pair sample into minor and major interactions according to the luminosity ratio of the galaxy members. We conclude that the characteristics of the interactions and the ratio of luminosity galaxy pair members involved in a merger are important parameters in setting galaxy properties.Fil: Mesa, Valeria Alejandra. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; ArgentinaFil: Alonso Giraldes, Maria Sol. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico San Juan. Instituto de Ciencias Astronomicas de la Tierra y del Espacio; ArgentinaFil: Garcia Lambas, Diego Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: O'Mill, Ana Laura. Universidade de Sao Paulo; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin