Biolog?a comparada de poblaciones colombianas de Anastrepha fraterculus y Anastrepha obliqua

57 p. Recurso Electr?nicoLa fruticultura es un rengl?n importante de la agricultura en Colombia, su comercializaci?n se ve limitado por barreras fitosanitarias a nivel internacional, debido a plagas cuarentenarias. Anastrepha obliqua y A. fraterculus son dos de las especies cuarentenarias m?s importantes debido a que afecta la producci?n de cultivos frutales como el mango y la guayaba. La informaci?n sobre aspectos b?sicos de bioecolog?a de estas especies es pr?cticamente inexistente en Colombia. El objetivo del presente trabajo fue obtener informaci?n sobre la biolog?a b?sica de A. obliqua y A. fraterculus que sirva como base para el desarrollo y mejoramiento de estrategias para su control. Se desarrollaron tablas de vida a partir de dos poblaciones por cada especie, colectadas en diferentes regiones del pa?s, mantenidas en el Laboratorio de Entomolog?a de la Universidad del Tolima. Se determinaron los ciclos de vida en laboratorio, se calcularon ?ndices poblacionales como mortalidad espec?fica y tasa neta de aumento. El an?lisis demostr? que las poblaciones de A. fraterculus presentan diferencias significativas en los estados huevo, larva I, larva III y pupa; en las poblaciones de A. obliqua se presentan diferencias entre los estados huevo, larva I y pupa. A nivel interespec?fico las especies no presentan diferencias significativas en la duraci?n de su ciclo. La poblaci?n con mayor R0 y Rm es Zarzal 35,0458 y 0,064136, respectivamente. La poblaci?n con el R0 y Rm m?s bajos fue Sibundoy, 9,6106 y 0,043471. Estos resultados sirven como base para futuras investigaciones con el fin de mejorar las estrategias de control de estas especies. Palabras clave: tabla de vida, par?metros demogr?ficos, moscas de la fruta.Colombian fruit production is an important economic sector in the agriculture; however, its marketing is limited by phytosanitary barriers at the international level, due to quarantine pests. Anastrepha obliqua and A. fraterculus are two of the most important quarantine species because it affects the production of fruit crops such as mango and guava. The knowledge on the basic bioecology of these species is incipient in Colombia. The objective of this work was to obtain information about the basic biology of A. obliqua and A. fraterculus? this information could offer information for the development and improvement of management strategies. Life tables were obtained from two populations for each species, collected in different regions of the country and reared in the Entomology Laboratory of the University of Tolima. The life cycles in laboratory were studied, population data like specific mortality and net rate of increase were calculated. The populations of A. fraterculus presented significant differences between egg, larval I, larval III and pupal stages; whereas in the populations of A. obliqua there were differences between egg, larval I and pupal stages. At an interspecific level, species do not show a greater difference in the duration of their cycle. The population with the highest R0 and Rm was Zarzal 35.0458 and 0.064136, respectively. The population with the lowest R0 and Rm was Sibundoy, 9.6106 and 0.043471. These results serve as a basis for future research in order to improve control strategies for these species. Key words: life table, demographic parameters, fruit flies

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

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

The physical origin of super-competitive accretion during the formation of the first supermassive black holes

Numerical simulations have shown the occurence of a scenario termed ''super-competitive accretion'', a term that describes a situation where only the central few objects grow supermassive while a larger number of stars compete for the reservoir, with significant accretion flows of $\gtrsim0.1$ M$_\odot$ yr$^{-1}$. This scenario particularly implies that the presence of fragmentation will not necessarily impeed the formation of a central massive object. We here explore this phenomenon using analytical estimates for growth via collisions and accretion, considering accretion due to self-gravity as well as Bondi-Hoyle accretion. Particularly, we explore under what conditions the accretion onto the central massive object breaks down, and derive a criterion that depends on the mass of the most massive object and the mass in fragments. For compact clusters with sizes about $0.1$~pc, we further find that the mass growth by collisions is comparable to the growth via accretion. Our results are validated through the comparison with numerical simulations, and we overall conclude that super-competitive accretion is a valid mechanism for the formation of very massive objects in the early Universe.Comment: 9 pages, 5 figures. Accepted for publication in MNRA

A comparative evaluation of interest point detectors and local descriptors for visual SLAM

Abstract In this paper we compare the behavior of different interest points detectors and descriptors under the conditions needed to be used as landmarks in vision-based simultaneous localization and mapping (SLAM). We evaluate the repeatability of the detectors, as well as the invariance and distinctiveness of the descriptors, under different perceptual conditions using sequences of images representing planar objects as well as 3D scenes. We believe that this information will be useful when selecting an appropriat

Variability in concentrations of potentially toxic elements in urban parks from six European cities

Use of a harmonised sampling regime has allowed comparison of concentrations of copper, chromium, nickel, lead and zinc in six urban parks located in different European cities differing markedly in their climate and industrial history. Wide concentrations ranges were found for copper, lead and zinc at most sites, but for chromium and nickel a wide range was only seen in the Italian park, where levels were also considerably greater than in other soils. As might be expected, the soils from older cities with a legacy of heavy manufacturing industry (Glasgow, Torino) were richest in potentially toxic elements (PTEs); soils from Ljubljana, Sevilla and Uppsala had intermediate metal contents, and soils from the most recently established park, in the least industrialised city (Aveiro), displayed lowest concentrations. When principal component analysis was applied to the data, associations were revealed between pH and organic carbon content; and between all five PTEs. When pH and organic carbon content were excluded from the PCA, a distinction became clear between copper, lead and zinc (the "urban" metals) on the one hand, and chromium and nickel on the other. Similar results were obtained for the surface (0-10 cm depth) and sub-surface (10-20 cm depth) samples. Comparisons with target or limit concentrations were limited by the existence of different legislation in different countries and the fact that few guidelines deal specifically with public-access urban soils intended for recreational use

Formation of supermassive stars in the first star clusters

The formation of supermassive stars is believed to be an essential intermediate step for the formation of the massive black hole seeds that become the supermassive black holes powering the quasars observed in the early Universe. Numerical simulations have shown that supermassive stars can form in atomic-cooling halos when protostars reach accretion rates higher than $\sim10^{-2}$ M$_\odot$ yr$^{-1}$ and fragmentation is suppressed on pc scales. It is however still uncertain if a supermassive star still emerges when fragmentation occurs at smaller scales and a cluster of stars is formed instead. In this work we explore the problem of massive object formation due to the interplay of collisions and accretion in star clusters at low metallicity. We model a small embedded cluster of accreting protostars following sub-parsec scale fragmentation during the collapse of a primordial gas cloud and follow its evolution by performing $N$-body plus hydrodynamical simulations. Our results show that supermassive stars with 10$^3$ and 10$^4$ M$_\odot$ are always formed due to the interplay of collisions and accretion, and in some cases these objects are part of a binary system. The resulting supermassive star is surrounded by tens of smaller stars with typical masses in the range $1$-$100$ M$_\odot$.Comment: 16 pages, 20 figures, accepted by MNRA

Investigation of proton damage in III-V semiconductors by optical spectroscopy

We studied the damage produced by 2MeV proton radiation on epitaxially grown InGaP/GaAs structure by means of spatially resolved Raman and photoluminescence (PL) spectroscopy. The irradiation was performed parallel to the sample surface in order to determine the proton penetration range in both compounds. An increase in the intensity of longitudinal optical phonons and a decrease in the luminescence were observed. We associate these changes with the creation of defects in the damaged region, also responsible for the observed change of the carrier concentration in the GaAs layer, determined by the shift of the phonon-plasmon coupled mode frequency. From the spatially resolved profile of the PL and phonon intensities, we obtained the proton range in both materials and we compared them with stopping and range of ions in matter simulations. The comparison between the experimentally obtained proton range and simulations shows a very good agreement for GaAs but a discrepancy of 20% for InGaP. This discrepancy can be explained in terms of limitations of the model to simulate the electronic orbitals and bonding structure of the simulated compound. In order to overcome this limitation, we propose an increase in 40% in the electronic stopping power for InGaP.This work was supported by BEC.AR FUNDACION YPF-CONICET 2013 (Argentina) and DFG within Grant No. SFB 787. ARG thanks the Spanish Ministry of Economy and Competitiveness (MINECO) for its support through Grant No. SEV-2015-0496 in the framework of the Spanish Severo Ochoa Centre of Excellence program.Peer reviewe

Sports grass : behaviour of AZ-1 cultivar of Pennisetum clandestinum Hochst. ex Chiov. (kikuyo). Paraná, Entre Ríos, Argentina

A fines de 2001 se incorporó al mercado argentino el cultivar AZ-1 de Pennisetum clandestinum Hochst. ex Chiov. (kikuyo) para ser utilizado en campos deportivos o con fines ornamentales. Con el propósito de caracterizar esta variedad comercial en el departamento Paraná (provincia de Entre Ríos, Argentina) se evaluó su comportamiento y aptitud para césped ornamental y/o deportivo en condiciones de mantenimiento para césped de calidad, bajo dos condiciones de drenaje. Se evaluaron cobertura, color, textura, distancia de entrenudos, grosor de estolones y período de dormición. El ensayo se realizó en Oro Verde, departamento Paraná, en un suelo Molisol y consistió en 2 tratamientos: con y sin drenaje, con 4 repeticiones cada uno. El tamaño de la parcela fue de 2,5 por 5,0 m. El diseño experimental utilizado fue parcelas apareadas y las mediciones se realizaron desde junio hasta noviembre de 2005. Las características climáticas locales son: temperatura media anual de 18,1°C y un régimen isohigro de 947,6 mm de precipitación anual. El cultivar se comportó como apto para césped en las características y condiciones de manejo evaluadas, sin diferencias entre los tratamientos con y sin drenaje. Presentó rápida implantación, niveles altos de cobertura, color claro y uniforme, textura media y estolones gruesos a medianos a través del tiempo. En invierno no perdió cobertura ni color. Se caracterizó como un césped no apto para campos deportivos de alta exigencia, pero recomendable para clubes de bajo presupuesto y mantenimiento.At the end of 2001, the AZ-1 cultivar of Pennisetum clandestinum Hochst. ex Chiov. (kikuyugrass) was incorporated into the Argentinean market to be used in sports fields or for ornamental purposes. In order to characterize such commercial variety in the geographic department of Paraná (Entre Ríos, Argentina), its behavior and aptitude were assessed as ornamental grass and/or sports grass both under high quality grass maintenance conditions and under two drainage conditions. Cover, colour, texture, internodes distance, stolon thickness, and dormancy period were evaluated. The trial was carried out in Oro Verde, department of Paraná in the province of Entre Ríos in a Molisol soil and it consisted of two treatments: with and without drainage and each treatment being repeated four times. The plot size was 2.5 x 5.0 m. The experimental design used was the paired - plot design and measurements were taken from June to November 2005. The area weather conditions are the following: average annual temperature of 18.1°C and an isohydro regimen of 947.6 mm of annual rainfall. The cultivar behaved as suitable for grass under the evaluated management conditions and characteristics, not showing differences as regards the treatments with or without drainage. It presented quick implantation, high cover levels, light and uniform colour, medium texture and thick stolons through time. In winter, cover and colour kept invariable. It was characterized as a grass not suitable for sports fields with high requirements, but advisable for low budget and maintenance condition clubs.Fil: Galli, Martín.Fil: Carponi, María S..Fil: Reinoso, Patricia D..Fil: Laurencena, María I..Fil: Butus, Marina.Fil: Scorciapino, Claudia

Hallazgo de W, Ni, Cu, Pb y Zn la Salina la Antigua Provincia de La Rioja, Argentina

Este trabajo forma parte del Quinto Congreso Latinoamericano de Geología, Argentina, 1982.Fil: Reinoso, Margarita. Servicio Minero Nacional; Argentina.Fil: Petrelli, Hugo. Servicio Minero Nacional; Argentina.El objetivo de este trabajo es estudiar el comportamiento de los iones metalíferos en la cuenca cerrada o semiabierta de condiciones oxidantes y temporariamente seca, para analizar la posibilidad de existencia de concentraciones de interés económico. Como la primera aproximación al tema se eligió la salina La Antigua, situada al pie del faldeo oeste de la Sierra Brava, en la provincia de La Rioja (Lamina I). En el mes de febrero de 1978 se realizaron tres calicatas alineadas perpendicularmente al borde de la salina, 1500 metros al norte del camino que la cruza, ver Lámina II, separadas 100 metros entre si, y de profundidades variables entre 25 cm y 75 cm, hasta alcanzar el primer nivel de agua. Las muestras así obtenidas fueron analizadas por Qi, Pb, Zn, W y Ni, no habiendo sido posible obtener los análisis por otros elementos por carecer el laboratorio quimico disponible del material necesario. También se dispone de los resultados del muestreo geoquimico panorámico de sedimentos fluviales de la vertiente occidental de la Sierra Brava, realizado por el Plan La Rioja de la Subsecretaria de Estado de Minería en el año 1972