VVV Survey Microlensing Events in the Galactic Center Region

Indexación: Scopus.We search for microlensing events in the highly reddened areas surrounding the Galactic center using the near-IR observations with the VISTA Variables in the Vía Láctea Survey (VVV). We report the discovery of 182 new microlensing events, based on observations acquired between 2010 and 2015. We present the color-magnitude diagrams of the microlensing sources for the VVV tiles b332, b333, and b334, which were independently analyzed, and show good qualitative agreement among themselves. We detect an excess of microlensing events in the central tile b333 in comparison with the other two tiles, suggesting that the microlensing optical depth keeps rising all the way to the Galactic center. We derive the Einstein radius crossing time for all of the observed events. The observed event timescales range from t E = 5 to 200 days. The resulting timescale distribution shows a mean timescale of days for the complete sample (N = 182 events), and days if restricted only for the red clump (RC) giant sources (N = 96 RC events). There are 20 long timescale events ( days) that suggest the presence of massive lenses (black holes) or disk-disk event. This work demonstrates that the VVV Survey is a powerful tool to detect intermediate/long timescale microlensing events in highly reddened areas, and it enables a number of future applications, from analyzing individual events to computing the statistics for the inner Galactic mass and kinematic distributions, in aid of future ground- and space-based experiments.http://iopscience.iop.org/article/10.3847/2041-8213/aa9b29/met

Mesoscopic modelling of bipolar charge evolution in CN-PPV LEDs

Since various chances are possible in the molecular structure of the repeat unit, substituted poly(para-phenylenevinylene) (PPV) has ben used as active component in light-emitting diodes (LEDs) to obtain light emission in a wide range of colours.A major aspect determining device performance is the competition between current flow, trapping and recombination within the polymer layer. By suitable Monte Carlo calculations, we have performed computer experiments in which bipolar charge carriers are injected at constant rate in polymer networks made of cyano-substituted PPV chains with variable length and orientation. The intra-molecular electronic properties used in these simulations were calculated by a quantum molecular dynamics method. In order to assess the influence of cyano-substitution on the properties of single-layer PPV LEDs, we have focused our attention on bipolar charge evolution in time. Specifically addressed are the differences in electric field strength needed for intra-molecular charge mobility of electrons and holes and their consequences at mesoscopic scale. (C) 2004 Elsevier B.V. All rights reserved

Computer simulation of electron transfer in molecular electronic devices

The study of electron transfer through individual molecules bound to metal electrodes has become important due to the potential application in molecular electronic devices. Since the electronic and atomic motions in these molecules influence each other they need to be treated self-consistently. We have used self-consistent quantum chemistry molecular dynamics calculations to discuss some of the issues related to electron transfer through a spatially symmetric [9,10-Bis((2′-para-mercaptophenyl)-ethinyl)-anthracene] and an asymmetric [1,4-Bis((2′-para-mercaptophenyl)-ethinyl)-2-acetyl-amino-5-nitro-benzene] molecule bound to metal electrodes. Specifically addressed are the effects of voltage inversion on electron transfer between electrodes through both molecules. Our results show an electron transfer behaviour that reproduces the spatial symmetry of the molecules in agreement with experimental current-voltage data. The change in time of electron density and dimerisation at specific atomic sites is also discussed.Fundação para a Ciência e a Tecnologia (FCT) - Programa Operacional “Ciência , Tecnologia, Inovação” - POCTI/CTM/41574/2001, SFRH/BD/11231/2002.Comunidade Europeia (CE). Fundo Europeu de Desenvolvimento Regional (FEDER)

THE ROLE OF CALCIUM ANTAGONIST ISRADIPINE ON THE PREGNANCY AND OFFSPRING OF RATS

Os bloqueadores de cálcio são utilizados em doenças cardiovasculares, usualmente em tratamentos de longa duração e ocasionalmente em mulheres grávidas. A isradipina é uma importante droga antihipertensiva, considerada segura na gravidez e sem efeitos teratogênicos. Neste estudo foram estudados, em ratos Wistar, os efeitos da isradipina sobre a implantação uterina, reabsorção fetal e sobre os níveis plasmáticos de cálcio, fosfato e proteínas totais. Foram utilizados 32 fêmeas e 12 machos com qualidade controlada. A droga foi administrada na água de beber durante 56 dias, sendo 35 antes do acasalamento e 21 durante a prenhêz. Em um grupo, foi realizada operação cesareana ao 20º / dia de gestação e em outro, os ratos nasceram de parto natural e foram observados durante 30 dias, com manutenção da administração de isradipina. Por ocasião da cesareana foram obtidas amostras de sangue de mães e filhotes, para determinação de cálcio, fosfato e proteínas totais plasmáticas. Para observar a influência da droga no / tratamento prolongado sobre os ossos, a mineralização do fêmur das mães foi avaliada. Os resultados mostraram que a isradipina estimulou a implantação uterina porém aumentou a reabsorção fetal. Nenhum efeito teratogênico foi observado, entretanto ocorreu diminuição significativa do peso dos filhotes. Os níveis plasmãticos de cálcio, fosfato e proteínas totais não foram alterados pela droga. O período da erupção dental não foi alterado nos filhotes nascidos de mães tratadas. Abstract Calcium blockers are used in cardiovascular diseases, usually in long term treatments and sometimes in pregnant women. Isradipine is an important antihypertensive drug, considered to be safe in pregnancy. In this study, the effects of isradipine were evaluated regarding to the uterine implantation, fetal reabsorption, plasmatic levels of calcium, phosphate and total protein of mother and offspring. Thirty-two female and 12 male quality-controlled Wistar rats were used. The drug was administered in drinking water for 56 days: 35 days before mating and 21 days along the pregnancy. In one group, caesarean surgery was performed on the 20th//day and in the other, isradipine treatment continued for the naturally born rats, which were observed along 30 days. During the caesarean, blood samples of mothers and newborns were taken and plasmatic / levels of calcium, phosphate and total proteins determined. To observe the drug influence on the bones, femur mineralization of mothers was evaluated. Results showed that isradipine stimulated uterine implantation; however, it increased the fetal reabsorption. No teratogenic effect was observed but newborns displayed a lower body weight. Plasmatic levels of calcium, phosphate and total proteins were not influenced by the drug. Dental eruption was not disturbed in the offspring born from the treated mothers

Intra-molecular properties of DMeOPPV studied by quantum molecular dynamics

Introducing methoxy electron donor groups into a poly(para-phenylene vinylene) (PPV) chain will lead to the appearance of unique electronic properties at the molecular scale which should affect the overall properties of light-emitting diodes based on these polymers. Self-consistent quantum molecular dynamics calculations have been used to provide information on intra-molecular properties of poly(2,5-dimethoxy-para-phenylene vinylene) (DMeOPPV), which are relevant for the modelling and characterization of polymer light-emitting diodes at nanometric length scale. We focus our attention on those properties that have been somewhat neglected in previous literature: the charge distribution associated with positive and negative charge carriers and their intra-molecular mobility when an electric field is applied.Fundação para a Ciência e a Tecnologia (FCT) – Programa Operacional “Ciência, Tecnologia, Inovação” - POCTI/CTM/41574/2001, SFRH/BD/11231/2002.Comunidade Europeia (CE). Fundo Europeu de Desenvolvimento Regional (FEDER

Modelling the effect of nonplanarity on charge transport along conjugated polymer chains

Conjugated polymers show interesting properties that make them appropriated for nanoelectronics. Several studies of poly(p-phenylene vinylene) (PPV) have suggested that each polymer chain consists of several planar segments, with conjugation length of nanoscale dimension, linked by twists or kinks. A pronounced twist between two planar segments in a PPV chain not only causes loss of main-chain conjugation but it may also alter electron and hole mobility along the chain, which has further implications for the percolation of charge through the polymer film. We used self-consistent quantum molecular dynamics calculations to provide information on the electric field needed to move the injected charges (either electrons or holes) along the planar segments of PPV and to cross the twist between two planar segments perpendicular to each other. Field-dependent charge mobility was also estimated for conjugated segments of various lengths. Our results suggest that electrons can cross the twist between adjacent planar segments for lower applied electric fields than holes if there is no more than one electronic charge (electron or hole) on the PPV chain, otherwise similar fields are needed.Fundação para a Ciência e a Tecnologia FCT) Programa Operacional “Ciência , Tecnologia, Inovação” – POCTI/CTM/41574/2001, CONC-REEQ/443/EEI/2001 e SFRH/BD/11231/200

The VVV Survey RR Lyrae Population in the Galactic Center Region

Indexación: Scopus.We gratefully acknowledge the use of data from the ESO Public Survey program ID 179.B-2002 taken with the VISTA telescope, and data products from the Cambridge Astronomical Survey Unit (CASU). Support for the authors is provided by the BASAL Center for Astrophysics and Associated Technologies (CATA) through grant PFB-06, and the Ministry for the Economy, Development, and Tourism, Programa Iniciativa Cientifica Milenio through grant IC120009, awarded to the Millennium Institute of Astrophysics (MAS). D.M. and M.Z. acknowledge support from FONDECYT Regular grants No. 1170121, and 1150345, respectively. P.H. acknowledges financial support from FONDECYT regular grant 1170305. F.G. acknowledge support from CONICYT-PCHA Doctorado Nacional 2017-21171485 and Proyecto Fondecyt Regular 1150345. J.A.-G. acknowledges support by FONDECYT Iniciacion 11150916. D.M. is also grateful for the hospitality of the Vatican Observatory. This research made use of Astropy, a community-developed core Python package for astronomy; Scikit-learn, NumPy, and matplotlib, a Python library for publication-quality graphics; and Aladin Sky Atlas, developed at CDS, Strasbourg Observatory, France, and TOPCAT.Deep near-IR images from the VISTA Variables in the V a L ctea (VVV) Survey were used to search for RR Lyrae stars within 100 arcmin from the Galactic Center. A large sample of 960 RR Lyrae of type ab (RRab) stars were discovered. A catalog is presented featuring the positions, magnitudes, colors, periods, and amplitudes for the sample, in addition to estimated reddenings, distances, and metallicities, and measured individual relative proper motions. We use the reddening-corrected Wesenheit magnitudes, defined as WKs Ks 0.428 J Ks = - ( - ), in order to isolate bona fide RRL belonging to the Galaxy Center, finding that 30 RRab are foreground/background objects. We measure a range of extinctions from AKs 0.19 = to 1.75 mag for the RRab in this region, finding that large extinction is the main cause of the sample incompleteness. The mean period is P =0.5446±0.0025 days, yielding a mean metallicity of [Fe/H] =-1.30±0.01 (ς = 0.33) dex for the RRab sample in the Galactic Center region. The median distance for the sample is D =8.05±0.02 kpc. We measure the RRab surface density using the less reddened region sampled here, finding a density of 1000 RRab/sq deg at a projected Galactocentric distance RG =1.6 deg. Under simple assumptions, this implies a large total mass (M>109Me) for the old and metal-poor population contained inside RG. We also measure accurate relative proper motions, from which we derive tangential velocity dispersions of ςVl =125.0 and ςVb =124.1 km s-1 along the Galactic longitude and latitude coordinates, respectively. The fact that these quantities are similar indicate that the bulk rotation of the RRab population is negligible, and implies that this population is supported by velocity dispersion. In summary, there are two main conclusions of this study. First, the population as a whole is no different from the outer bulge RRab, predominantly a metal-poor component that is shifted with respect to the Oosterhoff type I population defined by the globular clusters in the halo. Second, the RRab sample, as representative of the old and metal-poor stellar population in the region, has high velocity dispersions and zero rotation, suggesting a formation via dissipational collapse. ©2018. The American Astronomical Society. All rights reserved.https://iopscience.iop.org/article/10.3847/1538-4357/aacf9

Effect of molecular properties on the performance of polymer light-emitting diodes

The performance of a single layer polymer light-emitting diode depends on several interdependent factors, although recombination between electrons and holes within the polymer layer is believed to play an important role. Our aim is to carry out computer experiments in which bipolar charge carriers are injected in polymer networks made of poly(p-phenylene vinylene) chains randomly oriented. In these simulations, we follow the charge evolution in time from some initial state to the steady state. The intra-molecular properties of the polymer molecules obtained from self-consistent quantum molecular dynamics calculations are used in the mesoscopic model. The purpose of the present work is to clarify the effects of intra-molecular charge mobility and energy disorder on recombination efficiency. In particular, we find that charge mobility along the polymer chains has a serious influence on recombination within the polymer layer. Our results also show that energy disorder due to differences in ionization potential and electron affinity of neighbouring molecules affects mainly recombinations that occur near the electrodes at polymer chains parallel to them.Fundação para a Ciência e a Tecnologia (FCT) – Programa Operacional “Ciência, Tecnologia, Inovação” - POCTI/CTM/41574/2001Comunidade Europeia (CE). Fundo Europeu de Desenvolvimento Regional (FEDER

Modelling the effect of non-planarity on luminescence energy of conjugated polymers

We present theoretical investigations of structural and electronic properties of ground-state and low-lying excited singlet states in isolated chains of conjugated polymers using a self-consistent quantum molecular dynamics method. With this approach, we have determined the energy of both states as function of the twist angle between two planar segments of the same polymer chain, for polymer chains with variable length. The conjugated polymers investigated here are poly(para-phenylene vinylene) (PPV) and polydiacetylene (PDA). Our results show that the energy of the excited-state increases more than that of the ground-state, as the twist angle increases up to 90º degrees. The change in the twist angle of both polymers leads to a blueshift in luminescence transition energy, the effect being stronger in PPV when the planar segments have similar sizes. The predicted blueshift in both polymers is dependent on the chain length, the effect being more pronounced for shorter-chains.Comunidade Europeia (CE). Fundo Europeu de Desenvolvimento Regional (FEDER)Fundação para a Ciência e a Tecnologia (FCT) - Programa Operacional “Ciência , Tecnologia, Inovação” – POCTI/CTM/41574/2001, CONC-REEQ/443/2001 e SFRH/BD/11231/200

The increasing importance of a continence nurse specialist to improve outcomes and save costs of urinary incontinence care

__Background:__ In an ageing population, it is inevitable to improve the management of care for community-dwellingelderly with incontinence. A previous study showed that implementation of the Optimum Continence ServiceSpecification (OCSS) for urinary incontinence in community-dwelling elderly with four or more chronic diseasesresults in a reduction of urinary incontinence, an improved quality of life, and lower healt