BIRDS AROUND THE ROAD: EFFECTS OF A ROAD ON A SAVANNAH BIRD COMMUNITY IN SOUTHERN BRAZIL

ABSTRACT ∙ Birds are highly susceptible to habitat fragmentation, traffic noise, roadkills, and other disturbances generated by the presence of roads. These impacts are manifested in the structure of bird communities and are mainly noticed near road edges. The main goal of this study was to evaluate the effects of a road on a savannah bird community in southern Brazil. The study was carried out within the Espinilho State Park (ESP), Rio Grande do Sul state. The ESP is divided by a road and we quantified bird abundance and richness along three transects, parallel to the road at different distances from it (T1: 10 m, T2: 250 m, T3: 500 m). To estimate bird richness and abundance we sampled five point counts along each transect. Sampling took place throughout the month of January 2015, during the summer. Bird species were categorized according to their feeding habits and habitat use. Richness and abundance increased with greater distance from the road. Transects closer to the roads were less similar than those more distant from the road. Insectivore species and species that use grassland and Espinilho habitat were less common in transects nearest the road. Our data indicate that road edges alter the species composition and structure of the bird community in the ESP, although our limited temporal sampling means that our results should be treated as preliminary. This effect is due to some species being attracted by the road whereas others avoid it or decline. Based on our findings, we rein‐ force the recommendation that roads should be avoided near or within areas destined for conservation. If roads must be built within or around protected areas, studies on the impact of these roads and possible mitigation measures are essential and urgent.Resumo ∙ Efeitos de uma rodovia numa comunidade de aves de savana no sul do Brasil Aves são altamente suscetíveis a fragmentação do habitat, barulho de tráfego, atropelamentos e outros distúrbios gerados pela presença de rodovias. Estes impactos são manifestados principalmente na estrutura das comunidades de aves que ocupam as bordas de rodovias. O objetivo deste estudo foi avaliar os efeitos de uma rodovia sobre uma comunidade de aves de savana no sul do Brasil. O estudo foi desenvolvido no Parque estadual do Espinilho (PEA), estado do Rio Grande do Sul. O PEA é cortado pela rodovia BR472 e nós quantificamos a abundância e riqueza de aves em três transectos em diferentes distâncias e paralelos a rodovia (T1: 10 m, T2: 250 m, T3: 500 m). Para amostragem de riqueza e abundância das aves em cada ponto amostral e em cada transecto foi utilizado o método de “Point cont”. A amostragem ocorreu no mês de janeiro de 2015, durante o verão. As espécies de aves registradas foram categorizadas de acordo com o hábito alimentar e uso do ambiente.  A abundância e riqueza de aves aumentou com maior distância da rodovia. Os transectos mais próximos da rodovia mostraram menos similaridade que aqueles mais distantes. Espécies insetívoras e espécies que usam preferencialmente ambientes de campo e espinilho foram menos comuns nos transectos mais próximos da rodovia. Nossos dados indicam que os o efeito de borda gerado pela rodovia altera a composição e estrutura da comunidade de aves no PEA, embora nossa amostragem seja imitada ao período de verão. Isto ocorre em função da atração de algumas espécies para próximo da rodovia e exclusão ou redução populacional de outras. Com base nos nossos resultados, reforçamos a recomendação que rodovias devem ser evitadas próximas ou dentro de áreas destinadas a conservação. Em áreas protegidas onde as rodovias estão presentes faz‐se necessário estudos sobre os impactos das rodovias e possíveis medidas mitigadoras

HST measures of Mass Accretion Rates in the Orion Nebula Cluster

The present observational understanding of the evolution of the mass accretion rates (Macc) in pre-main sequence stars is limited by the lack of accurate measurements of Macc over homogeneous and large statistical samples of young stars. Such observational effort is needed to properly constrain the theory of star formation and disk evolution. Based on HST/WFPC2 observations, we present a study of Macc for a sample of \sim 700 sources in the Orion Nebula Cluster, ranging from the Hydrogen-burning limit to M\ast \sim 2M\odot. We derive Macc from both the U-band excess and the H{\alpha} luminosity (LH{\alpha}), after determining empirically both the shape of the typical accretion spectrum across the Balmer jump and the relation between the accretion luminosity (Lacc) and LH{\alpha}, that is Lacc/L\odot = (1.31\pm0.03)\cdotLH{\alpha}/L\odot + (2.63\pm 0.13). Given our large statistical sample, we are able to accurately investigate relations between Macc and the parameters of the central star such as mass and age. We clearly find Macc to increase with stellar mass, and decrease over evolutionary time, but we also find strong evidence that the decay of Macc with stellar age occurs over longer timescales for more massive PMS stars. Our best fit relation between these parameters is given by: log(Macc/M\odot\cdotyr)=(-5.12 \pm 0.86) -(0.46 \pm 0.13) \cdot log(t/yr) -(5.75 \pm 1.47)\cdot log(M\ast/M\odot) + (1.17 \pm 0.23)\cdot log(t/yr) \cdot log(M\ast/M\odot). These results also suggest that the similarity solution model could be revised for sources with M\ast > 0.5M\odot. Finally, we do not find a clear trend indicating environmental effects on the accretion properties of the sources.Comment: 17 pages, 15 figures, accepted for publication in Ap

Value of the magnetic resonance image of the lumbar spine with load in the evaluation of stenosis of the lumbar spinal canal

UNIFESPUNIFESPSciEL

Image diagnosis for evaluation of heterotopic ossification

UNIFESP-EPM DDIDiagnósticos da AméricaUNIFESP-EPMHospital São LuizUNIFESP, EPM, DDIUNIFESP, EPMSciEL

A New Method for the Assessment of Age and Age-Spread of Pre-Main Sequence Stars in Young Stellar Associations of the Magellanic Clouds

We present a new method for the evaluation of the age and age-spread among pre-main-sequence (PMS) stars in star-forming regions in the Magellanic Clouds, accounting simultaneously for photometric errors, unresolved binarity, differential extinction, stellar variability, accretion and crowding. The application of the method is performed with the statistical construction of synthetic color-magnitude diagrams using PMS evolutionary models. We convert each isochrone into 2D probability distributions of artificial PMS stars in the CMD by applying the aforementioned biases that dislocate these stars from their original CMD positions. A maximum-likelihood technique is then applied to derive the probability for each observed star to have a certain age, as well as the best age for the entire cluster. We apply our method to the photometric catalog of ~2000 PMS stars in the young association LH 95 in the LMC, based on the deepest HST/ACS imaging ever performed toward this galaxy, with a detection limit of V~28, corresponding to M~0.2 Msun. Our treatment shows that the age determination is very sensitive to the considered grid of evolutionary models and the assumed binary fraction. The age of LH 95 is found to vary from 2.8 Myr to 4.4 Myr, depending on these factors. Our analysis allows us to disentangle a real age-spread from the apparent CMD-broadening caused by the physical and observational biases. We find that LH 95 hosts an age-spread well represented by a gaussian distribution with a FWHM of the order of 2.8 Myr to 4.2 Myr depending on the model and binary fraction. We detect a dependence of the average age of the system with stellar mass. This dependence does not appear to have any physical meaning, being rather due to imperfections of the PMS evolutionary models, which tend to predict lower ages for the intermediate masses, and higher ages for low-mass stars.Comment: 19 pages, 16 figures, accepted for publication by the Astrophysical Journa

Prior specification via prior predictive matching: Poisson matrix factorization and beyond

Hyperparameter optimization for machine learning models is typically carried out by some sort of cross-validation procedure or global optimization, both of which require running the learning algorithm numerous times. We show that for Bayesian hierarchical models there is an appealing alternative that allows selecting good hyperparameters without learning the model parameters during the process at all, facilitated by the prior predictive distribution that marginalizes out the model parameters. We propose an approach that matches suitable statistics of the prior predictive distribution with ones provided by an expert and apply the general concept for matrix factorization models. For some Poisson matrix factorization models we can analytically obtain exact hyperparameters, including the number of factors, and for more complex models we propose a model-independent optimization procedure

Aplicação e análise de métodos estocásticos de otimização ao modelo de múltiplas fontes pontuais ponderadas para a determinação da radiação em chamas

A determinação da emissão de radiação em chamas é um problema frequente em projetos de caldeiras, queimadores e equipamentos similares, sendo sua modelagem fundamental para controle de processos, para redução de custos e para prevenção de falhas e acidentes. Alguns modelos foram propostos, entre eles o chamado WMP, mas poucos estudos se dedicaram a desenvolvê-los e avaliá-los. Estudos anteriores buscaram relacionar os parâmetros do modelo WMP com o fenômeno da combustão e otimizá-los com a Otimização Extrema Generalizada. Existe contudo a possibilidade de que outros métodos sejam mais e cientes sem perda de qualidade. Com isso em mente, este estudo busca aplicar e avaliar o desempenho de diferentes algoritmos estocásticos de otimização ao modelo WMP. É feita uma revisão do estado da arte, sendo escolhidos cinco algoritmos para análise: Otimização de Lobos Cinzentos, Otimização de Manadas Egoístas, Algoritmo Genético, Algoritmo de Dentes-de-Leão e Otimização de Bactérias. Também é proposto um procedimento de calibração desses algoritmos baseada na metodologia de Projeto de Experimentos. O Algoritmo de Lobos Cinzentos se mostrou como o de melhor desempenho, sendo seus resultados médios e desvios padrões satisfatórios em comparação com os demais. O Algoritmo Genético e o Algoritmo de Dentes-de-Leão mostraram desempenho satisfatório, mas necessitando mais execuções para a con rmação da resposta. A Otimização de Manadas Egoístas e a Otimização de Bactérias exibiram desempenhos inferiores, com altas médias e desvios. A metodologia de Projeto de Experimentos se mostrou adequada para algoritmos com poucos parâmetros, mas perde qualidade à medida que o número de parâ- metros aumenta. Os melhores resultados foram encontrados com maiores quantidades de fontes emissoras e maiores comprimentos de distribuição, concordando com a tendência apresentada por trabalhos anteriores. O melhor resultado foi encontrado pelo Algoritmo de Dentes-de-Leão, na con guração com sete fontes emissoras e comprimento de distribui ção das fontes equivalente a 2,5 vezes o comprimento visível da chama, com um valor de função objetivo de 0,216 kW/m2.The determination of radiation emission on ames is a frequent problem designing boilers, burners and similar equipments, its modelling being therefore fundamental for process control, cost reduction and prevention of failures and accidents. Some models have been proposed, among them the WMP model, however little study has been dedicated to solve and evaluate them. Some previous researches sought to correlate WMP model parameters to the phenomenon of combustion and to optimise them with the Generalised Extreme Optimisation. However there is the possibility of other optimisation methods being more e cient without loss of quality. Having this in mind, this study aims to apply and evaluate the performance of di erent stochastic optimisation algorithms applied to the WMP model. A bibliographical review of the state of the art is made, being chosen ve methods to be analysed: Grey Wolf Optimiser, Sel sh Herds Optimiser, Genetic Algorithms, Dandelion Algorithm and Bacterial Foraging Optimisation. Also, a procedure for the calibration of these methods is proposed, based on the Design of Experiments methodology. The Grey Wolf Optimizer presents the best performance, with satisfactory mean results and standard deviations. The Genetic Algorithm and the Dandelion Algorithm showed good satisfactory results, but also the necessity of a deeper conference of results. The Sel sh Herds Optimiser and the Bacterial Foraging Optimisation had inferior performance, with higher means and deviations. The Design of Experiments methodology was satisfactory for algorithms with few parameters, but lost quality as the number of parameters increased. The best results were found for higher quantities of sources and larger distribution lengths, which agrees with tendencies presented by previous works. The best result was found by the Dandelion Algorithm, employing 7 point sources and a distribution length equivalent to 2.5 times the visible ame length, presenting an objective function value of 0.216 kW/m2

Rapid star formation and global gravitational collapse

Most young stars in nearby molecular clouds have estimated ages of 1–2 Myr, suggesting that star formation is rapid. However, small numbers of stars in these regions with inferred ages of > rsim 5–10 Myr have been cited to argue that star formation is instead a slow, quasi‐static process. When considering these alternative pictures it is important to recognize that the age spread in a given star‐forming cloud is necessarily an upper limit to the time‐scales of local collapse, as not all spatially distinct regions will start contracting at precisely the same instant. Moreover, star‐forming clouds may dynamically evolve on time‐scales of a few Myr; in particular, global gravitational contraction will tend to yield increasing star formation rates with time due to generally increasing local gas densities. We show that two different numerical simulations of dynamic, flow‐driven molecular cloud formation and evolution (1) predict age spreads for the main stellar population roughly consistent with observations and (2) raise the possibility of forming small numbers of stars early in cloud evolution, before global contraction concentrates the gas and the bulk of the stellar population is produced. In general, the existence of a small number of older stars among a generally much younger population is consistent with the picture of dynamic star formation and may even provide clues to the time evolution of star‐forming clouds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90399/1/j.1365-2966.2011.20131.x.pd

Quantitative Evidence for an Intrinsic Age Spread in the Orion Nebula Cluster

Aims. We present a study of the distribution of stellar ages in the Orion Nebula Cluster (ONC) based on accurate HST photometry taken from the HST Treasury Program observations of the ONC utilizing the most recent estimate of the cluster's distance (Menten et al. 2007). We investigate the presence of an intrinsic age spread in the region and a possible trend of age with the spatial distribution. Methods. We estimate the extinction and accretion luminosity towards each source by performing synthetic photometry on an empirical calibration of atmospheric models (Da Rio et al. 2010) using the package Chorizos (Maiz-Apellaniz 2004). The position of the sources in the HR-diagram is compared with different theoretical isochrones to estimate the mean cluster age and age dispersion. Through Monte Carlo simulations we quantify the amount of intrinsic age spread in the region, taking into account uncertainties on the distance, spectral type, extinction, unresolved binaries, accretion and photometric variability. Results. According to Siess et al. (2000) evolutionary models the mean age of the Cluster is 2.2 Myr with a scatter of few Myrs. With Monte Carlo simulations we find that the observed age spread is inconsistent with a coeval stellar population, but is in agreement with a star formation activity between 1.5 and 3.5 Myrs. We also observe light evidence for a trend of ages with spatial distribution.Comment: 12 pages, 12 figures, Accepted for publication in Astronomy and Astrophysic

Are There Age Spreads in Star Forming Regions?

A luminosity spread at a given effective temperature is ubiquitously seen in the Hertzsprung-Russell (HR) diagrams of young star forming regions and often interpreted in terms of a prolonged period (>=10 Myr) of star formation. I review the evidence that the observed luminosity spreads are genuine and not caused by astrophysical sources of scatter. I then address whether the luminosity spreads necessarily imply large age spreads, by comparing HR diagram ages with ages from independent clocks such as stellar rotation rate, the presence of circumstellar material and lithium depletion. I argue that whilst there probably is a true luminosity dispersion, there is little evidence to support age spreads larger than a few Myr. This paradox could be resolved by brief periods of rapid accretion during the class I pre main-sequence phase.Comment: To appear in the proceedings of JENAM10: Star Clusters in the Era of Large Surveys, 8 page