Phage inducible islands in the gram-positive cocci

The SaPIs are a cohesive subfamily of extremely common phage-inducible chromosomal islands (PICIs) that reside quiescently at specific att sites in the staphylococcal chromosome and are induced by helper phages to excise and replicate. They are usually packaged in small capsids composed of phage virion proteins, giving rise to very high transfer frequencies, which they enhance by interfering with helper phage reproduction. As the SaPIs represent a highly successful biological strategy, with many natural Staphylococcus aureus strains containing two or more, we assumed that similar elements would be widespread in the Gram-positive cocci. On the basis of resemblance to the paradigmatic SaPI genome, we have readily identified large cohesive families of similar elements in the lactococci and pneumococci/streptococci plus a few such elements in Enterococcus faecalis. Based on extensive ortholog analyses, we found that the PICI elements in the four different genera all represent distinct but parallel lineages, suggesting that they represent convergent evolution towards a highly successful lifestyle. We have characterized in depth the enterococcal element, EfCIV583, and have shown that it very closely resembles the SaPIs in functionality as well as in genome organization, setting the stage for expansion of the study of elements of this type. In summary, our findings greatly broaden the PICI family to include elements from at least three genera of cocci

Fast direct solution of method of moments applied to multiscale problems

In a recent publication [1], we proposed a new convergence criterion for the Adapted Cross Approximation (ACA) algorithm, based on random sampling of the matrix that represents the residual error at each step of the algorithm. We presented some practical examples involving RCS computations of perfectly conducting benchmark targets exhibiting multiscale features, meaning that the mesh-size of the discrete model of the target is highly variable. These examples demonstrated a considerable improvement in the accuracy of the RCS result without appreciable loss of efficiency. In the presented examples, the solution was obtained by an iterative solver applied to an ACA-compressed Method of Moments impedance matrix. In this paper we apply the new method from [1] to the direct (non-iterative) solution of the MoM matrix. The results demonstrate that in this case, the advantage of the new method is far more important. Compared to ordinary ACA, the same accuracy is obtained in less than a quarter of the computation time

Predatory insects in lentic freshwater habitats from Northwest Patagonia: richness and phenology

The main purpose of this work was to study the richness, phenology and abundance of predatory insects throughout the hydroperiod and how they relate to the environmental parameters in lentic bodies of water in northwest Patagonia. Nineteen fishless wetlands and three wetlands with fish were studied, which are located in the surroundings of Nahuel Huapi National Park. Biotic and abiotic variables were measured during the hydroperiod of each wetland. The dip-netting sampling technique was used to determine the richness of predatory insects and to study the phenology of the dominant species in four wetlands. Species richness in temporary wetlands ranged from 1 to 9 species per wetland and does not differ from that observed in the permanent environments with or without fish predators. Maximum insect richness was recorded in late spring and was associated to the maximum depth of the wetland and its structural complexity as well as to the duration of the hydroperiod.Fil: Jara, Fabian Gaston. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; ArgentinaFil: Perotti, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; ArgentinaFil: Ubeda, Carmen A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; Argentin

Validation of ERA5-Land temperature and relative humidity on four Peruvian glaciers using on-glacier observations

Weather and climate conditions drive the evolution of tropical glaciers which play an important role as water reservoirs for Peruvian inhabitants in the arid coast and semi-arid Andean region. The scarcity of long-term high-quality observations over Peruvian glaciers has motivated the extensive use of reanalysis data to describe the climatic evolution of these glaciers. However, the representativeness and uncertainties of these reanalysis products over these glaciers are still poorly constrained. This study evaluates the ability of the ERA5-Land reanalysis (ERA5L) to reproduce hourly and monthly 2 m air temperature and relative humidity (T2m and Rh2m, respectively) over several Peruvian glaciers. We compared the ERA5L with data from four on-glacier automatic weather stations (AWS), whose hourly time series were completed with nearby stations, for the period January 2017 to December 2019. Results indicates a better performance of the reanalysis for T2m (r >0.80) than for Rh2m (similar to 0.4<

M4 Core Project with HST - III. Search for variable stars in the primary field

We present the results of a photometric search for variable stars in the core of the Galactic globular cluster M4. The input data are a large and unprecedented set of deep Hubble Space Telescope WFC3 images (large program GO-12911; 120 orbits allocated), primarily aimed at probing binaries with massive companions by detecting their astrometric wobbles. Though these data were not optimised to carry out a time-resolved photometric survey, their exquisite precision, spatial resolution and dynamic range enabled us to firmly detect 38 variable stars, of which 20 were previously unpublished. They include 19 cluster-member eclipsing binaries (confirming the large binary fraction of M4), RR Lyrae, and objects with known X-ray counterparts. We improved and revised the parameters of some among published variables.Comment: 11 pages, 5 figures, 2 tables. Accepted for publication in MNRA

Estimación de la fitomasa aérea mediante el uso del disco en una asociación de alfalfa y pasto ovillo

El objetivo del presente trabajo fue el de calibrar un disco para relacionar altura con rendimiento de forraje. Se utilizaron dos pasturas asociadas de alfalfa (Medicago saliva L.) y pasto ovillo (Dactylis glomerata). Es importante destacar que ambas pasturas eran alfalfas dominantes (alfalfa 78% y pasto ovillo 22%). Este método se evaluó para ser utilizado como un método práctico y rápido que permita estimar el rendimiento forrajero (kg MS/ha). La calibración se realizó en el establecimiento agropecuario "La María Pilar", ubicado en el departamento Catriló, durante otoño, primavera y verano de 1995 y verano de 1996. Los muestreos se realizaron al iniciar el pastoreo. La frecuencia de corte fue de. 23 días y se efectuaron 10 estimaciones en cada pastura. En cada fecha de corte se tomaron 30 muestras circulares de 0,166 m2 de superficie, se cortaron y secaron en estufa. La fitomasa se relacionó con la altura medida con el disco. Dicha relación fue lineal (p<0,05). No se encontraron diferencias (p<0,05) entre pasturas y fechas de muestreo. Se obtuvo una ecuación general Y = 134,7 x H donde Y = fitomasa aérea (kg/ha) y H = altura medida con el disco (cm). Esta no permitió lograr estimaciones confiables de la fitomasa aérea. Sin embargo, el método podría ser utilizado en un procedimiento de doble muestreo que consistida en realizar un número importante de estimaciones con el disco y relacionarlo con un pequeño número de cortes. Este método, si bien puede no tener aplicaciones en los casos en que se desee lograr gran precisión en la estimación de rendimientos, tienen la gran ventaja de su facilidad de uso y rapidez y podría ser usado a nivel productor, previa calibración por un técnico.Director: lng. Agr. Oscar Hernández y Codirector: lng. Agr. Carlos María Ferri, Cátedra de Forrajicultura y manejo de pasturas