Matching the dark matter profiles of dSph galaxies with those of simulated satellites: a two parameter comparison

We compare the dark matter halos' structural parameters derived for four Milky Way dwarf spheroidal galaxies to those of subhalos found in cosmological $N$-body simulations. We confirm that estimates of the mass at a single fixed radius are fully consistent with the observations. However, when a second structural parameter such as the logarithmic slope of the dark halo density profile measured close to the half-light radius is included in the comparison, we find little to no overlap between the satellites and the subhalos. Typically the right mass subhalos have steeper profiles at these radii than measurements of the dSph suggest. Using energy arguments we explore if it is possible to solve this discrepancy by invoking baryonic effects. Assuming that feedback from supernovae can lead to a reshaping of the halos, we compute the required efficiency and find entirely plausible values for a significant fraction of the subhalos and even as low as 0.1%. This implies that care must be taken not to exaggerate the effect of supernovae feedback as this could make the halos too shallow. These results could be used to calibrate and possibly constrain feedback recipes in hydrodynamical simulations.Comment: 6 pages, 3 figures, submitted to ApJ

Characterization of dynamical regimes and entanglement sudden death in a microcavity quantum - dot system

The relation between the dynamical regimes (weak and strong coupling) and entanglement for a dissipative quantum - dot microcavity system is studied. In the framework of a phenomenological temperature model an analysis in both, temporal (population dynamics) and frequency domain (photoluminescence) is carried out in order to identify the associated dynamical behavior. The Wigner function and concurrence are employed to quantify the entanglement in each regime. We find that sudden death of entanglement is a typical characteristic of the strong coupling regime.Comment: To appear in Journal of Physics: Condensed Matte

Polariton Lasing in a Multilevel Quantum Dot Strongly Coupled To a Single Photon Mode

We present an approximate analytic expression for the photoluminescence spectral function of a model polariton system, which describes a quantum dot, with a finite number of fermionic levels, strongly interacting with the lowest photon mode of a pillar microcavity. Energy eigenvalues and wavefunctions of the electron-hole-photon system are obtained by numerically diagonalizing the Hamiltonian. Pumping and photon losses through the cavity mirrors are described with a master equation, which is solved in order to determine the stationary density matrix. The photon first-order correlation function, from which the spectral function is found, is computed with the help of the Quantum Regression Theorem. The spectral function qualitatively describes the polariton lasing regime in the model, corresponding to pumping rates two orders of magnitude lower than those needed for ordinary (photon) lasing. The second-order coherence functions for the photon and the electron-hole subsystems are computed as functions of the pumping rate.Comment: version accepted in Phys. Rev.

Comparing reverse complementary genomic words based on their distance distributions and frequencies

In this work we study reverse complementary genomic word pairs in the human DNA, by comparing both the distance distribution and the frequency of a word to those of its reverse complement. Several measures of dissimilarity between distance distributions are considered, and it is found that the peak dissimilarity works best in this setting. We report the existence of reverse complementary word pairs with very dissimilar distance distributions, as well as word pairs with very similar distance distributions even when both distributions are irregular and contain strong peaks. The association between distribution dissimilarity and frequency discrepancy is explored also, and it is speculated that symmetric pairs combining low and high values of each measure may uncover features of interest. Taken together, our results suggest that some asymmetries in the human genome go far beyond Chargaff's rules. This study uses both the complete human genome and its repeat-masked version.Comment: Post-print of a paper accepted to publication in "Interdisciplinary Sciences: Computational Life Sciences" (ISSN: 1913-2751, ESSN: 1867-1462

Dissimilar Symmetric Word Pairs in the Human Genome

In this work we explore the dissimilarity between symmetric word pairs, by comparing the inter-word distance distribution of a word to that of its reversed complement. We propose a new measure of dissimilarity between such distributions. Since symmetric pairs with different patterns could point to evolutionary features, we search for the pairs with the most dissimilar behaviour. We focus our study on the complete human genome and its repeat-masked version.Comment: Submitted 13-Feb-2017; accepted, after a minor revision, 17-Mar-2017; 11th International Conference on Practical Applications of Computational Biology & Bioinformatics, PACBB 2017, Porto, Portugal, 21-23 June, 201

Size-Controlled Water-Soluble Ag Nanoparticles

Ag nanoparticles of two different sizes (1 and 4 nm) were prepared within an apoferritin cavity by using an Ag+-loaded apoferritin as a nanoconfined environment for their construction. The initial amount of Ag' ions injected in the apoferritin cavity dictates the size of the final Ag particles. The protein shell prevents bulk aggregation of the metal particles, which renders them water soluble and extremely stable

Erosion of materials used in heart valves prosthesis

Se estudia la erosión de materiales utilizados en la construcción de prótesis de válvulas cardíacas, Acero inoxidable 316 y Poli-metacrilato de metilo (PMMA) a niveles de desgaste bajos, esperados en estos dispositivos. Como material erosivo se utilizó SiC 220 mesh (65 μm de diámetro), en dos composiciones diferentes: 0,1 y 1 % en peso, suspendidas en una solución de glucosa al 50%P/P, (viscosidad de 0,01540 kg/(m.s)). Se usó un flujo de 2200 cm3/min y dos tamaños de boquillas de: 2,3 y 6,4 mm de diámetro, en dos ángulos de incidencia diferentes,60º y 90º. Los ensayos se realizaron por un período de 11 horas. Se partió de probetas de PMMA y Acero inoxidable 316 pulidas a espejo. Las escaras de desgaste se observaron al microscopio óptico. El tipo de fallas observadas en las probetas luego de los ensayos fueron: Puntos o cráteres (pequeños y grandes), Rayas largas, Rayas cortas y Rayas en forma de comas. En PMMA el desgaste se incrementó al aumentar la cantidad de partículas erosivas, tanto en los ensayos a 60º como a 90º. En cambio, no se observaron cambios en el nivel de con el ángulo de incidencia. En el acero inoxidable 316 se observó un incremento en el nivel de desgaste al reducir el ángulo de incidencia, de 90º a 60º.Erosion of poly-methil-metacrilate (PMMA) and 316 stainless steel, materials used in the fabrication of prosthetic heart valves, were studied. Particles of SiC, 65 μm in diameter (200 mesh), are used as erosive materials carried on a glucose solution as a carrier fluid. Two compositions of particles were used: 0.1 and 1 %wt. A flow rate of 2200 cm3 /min and two different outlet holes were used, the sample was located at 3 cm approximately of the outlet hole. The tests were performed for 11 hours. The initial surface of the PMMA and the stainless steel were polished up to a mirror like surface. The erosion scars were observed by optical microscopy. The types of failures found were: points or craters (smalls or larges), large scratches, short scratches and comma-like scratches. On the PMMA the wear increase when the amount of particles increase; however, no difference was observed when the incidence angle was changed. On the 316 stainless steel there the wear increased when the incidence angle change from 90º to 60 º.Fil: Rosenberger, Mario Roberto. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; ArgentinaFil: Guerrero, L. A.. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; ArgentinaFil: Vera, Maria Laura. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; ArgentinaFil: Schvezov, Carlos Enrique. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnológico Nordeste. Instituto de Materiales de Misiones; Argentin

Size structure of Olive Ridley turtle Lepidochelys olivacea (Testudines: Cheloniidae) in Tumbes, Peru

En el presente trabajo se analizó la estructura de tallas de ejemplares de tortuga pico de loro Lepidochelys olivacea, varados y capturados incidentalmente en las playas de Tumbes, Perú (3º38’9,5”S – 80º36’2,48”W y 3º57’21,3”S – 80º57’45,72”W), desde noviembre de 2006 a octubre de 2011. El área de estudio se dividió en tres zonas contiguas, limitadas por las quebradas más activas (Bocapán, El Rubio y Peña Negra). Se registraron 39 ejemplares (74,4% varados y 25,6% capturados incidentalmente), cuyas tallas variaron de 45 a 75 cm LCC (62,5±5,7 cm LCC). El 64,1% correspondió a individuos sub-adultos (<65 cm LCC; n= 25). Espacialmente la mayor cantidad de registros ocurrieron en las zonas 3 y 2, en las cuales porcentajes superiores al 60% se consideraron sub-adultos; mientras que en la zona 1, el 83% fue adulto. Temporalmente en la época lluviosa se registró la mayoría de las observaciones (59%), en la cual el 78,3% de ejemplares se consideró sub–adulto; siendo mayor que en la época seca (43,8%). Las tallas presentaron diferencias significativas entre zonas y épocas climáticas. Se corroboró el patrón de distribución latitudinal por estados de madurez aparente (más adultos en el norte). La presencia del componente adulto indicaría que el litoral de Tumbes sería una potencial zona de anidamiento de L. olivacea, con mayores probabilidades de ovoposición en época seca, corroborada por los eventos de anidamiento recientes.In this paper we analyzed the size structure of Olive Ridley turtle Lepidochelys olivacea, from individuals stranded and incidentally caught in beaches of Tumbes, Peru (3º38’9.5”S – 80º36’2.48”W; 3º57’21.3”S – 80º57’45.72”W), since November 2006 to October 2011. The study area was divided into three contiguous areas, which were limited by the most active streams (Bocapan, El Rubio and Peña Negra). There were 39 individuals (74.4% stranded and 25.6% caught incidentally), with sizes ranged from 45 to 75 cm CCL (62.5±5.7 cm CCL). 64.1% was considered sub-adult individuals (<65 cm CCL, n= 25). Spatially the largest number of records occurred in zones 3 and 2, in which percentages above 60% were considered sub-adults, while in zone 1, 83% was adult. Temporarily in the rainy season were registered the majority of the observations (59%), in which 78.3% of specimens was sub-adult, being higher than in the dry season (43.8%). Sizes showed significant differences between zones and climatic seasons. It was confirmed the latitudinal distribution pattern by apparent maturity stages (more adults in the north). Adults’ occurrences suggest that Tumbes coast would be a potential nesting area of L. olivacea, most likely to oviposit in dry season, it which is supported by recent nesting events

Segmentation of DNA into coding and noncoding regions based on inter-STOP symbols distances

In this study we set to explore the potentialities of the inter-genomic symbols distance for finding the coding regions in DNA sequences. We use the distance between STOP symbols in the DNA sequence and a chi-square statistic to evaluate the nonhomogeneity of the three possible reading frames. The results of this exploratory study suggest that inter-STOP symbols distance has strong ability to discriminate coding regions.publishe