Intragroup diffuse light in compact groups of galaxies – II. HCG 15, 35 and 51     

C. Da Rocha  B. L. Ziegler  C. Mendes de Oliveira 《Monthly notices of the Royal Astronomical Society》2008,388(3):1433-1443

This continuing study of intragroup light in compact groups of galaxies aims to establish new constraints to models of formation and evolution of galaxy groups, specially of compact groups, which are a key part in the evolution of larger structures, such as clusters. In this paper we present three additional groups (HCG 15, 35 and 51) using deep wide-field B - and R -band images observed with the LAICA camera at the 3.5-m telescope at the Calar Alto observatory (CAHA). This instrument provides us with very stable flat-fielding, a mandatory condition for reliably measuring intragroup diffuse light. The images were analysed with the ov_wav package, a wavelet technique that allows us to uncover the intragroup component in an unprecedented way. We have detected that 19, 15 and 26 per cent of the total light of HCG 15, 35 and 51, respectively, are in the diffuse component, with colours that are compatible with old stellar populations and with mean surface brightness that can be as low as 28.4 B mag arcsec⁻². Dynamical masses, crossing times and mass-to-light ratios were recalculated using the new group parameters. Also tidal features were analysed using the wavelet technique.  相似文献   

Non-random phases in non-trivial topologies     

Patrick Dineen  Graca Rocha  Peter Coles 《Monthly notices of the Royal Astronomical Society》2005,358(4):1285-1289

We present a new technique for constraining the topology of the Universe. The method exploits the existence of correlations in the phases of the spherical harmonic coefficients of the cosmic microwave background (CMB) temperature pattern associated with matched pairs of circles seen in the sky in universes with non-trivial topology. The method is computationally faster than all other statistics developed to hunt for these matched circles. We applied the method to a range of simulations with topologies of various forms and on different scales. A characteristic form of phase correlation is found in the simulations. We also applied the method to preliminary CMB maps derived from WMAP , but the separation of topological effects from e.g. foregrounds is not straightforward.  相似文献   

Determination of oxadiazon residues in the field treated soil with and without organic matter incorporated     

Kassio Ferreira Mendes  Marcelo Rodrigues dos Reis  Ana Beatriz Rocha de Jesus Passos  Miriam Hiroko Inoue  Antônio Alberto Silva  Daniel Valadão Silva 《Environmental Earth Sciences》2016,75(3):222

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Vessel biofouling as an inadvertent vector of benthic invertebrates occurring in Brazil     

Farrapeira CM  Tenório Dde O  Amaral FD 《Marine pollution bulletin》2011,62(4):832-839

This article reviews the literature involving benthic invertebrates that are cited in association with hull fouling, reporting the species that occur on the Brazilian coast and evaluating the importance of this vector for the introduction of nonindigenous and cryptogenic invertebrates in Brazil. It discusses some of the strategies that were used by the species that allowed for their overseas transport and made it easier to cross natural barriers that otherwise would have been obstacles to their dispersion. The compiled data list 343 species (65% nonindigenous and 35% cryptogenic), mainly from the northwestern Atlantic Ocean. The traveling fauna, composed mostly of cosmopolitan species (70.3%), is primarily euryhaline and marine stenohaline, with sessile and sedentary habits. After delineating the shipborne species’ ecological profiles and traveling strategies and evaluating their overlapping vectors, we concluded that hull vessels were the main vector of introduction to the Brazilian coast for 89.8% of the compiled species.  相似文献   

Assessment of the leachate movement in a sealed landfill using geophysical methods     

Elsa C. Ramalho  Amélia Carvalho Dill  Rui Rocha 《Environmental Earth Sciences》2013,68(2):343-354

This paper describes a case study concerning the use of integrated geophysical methods applied to environmental assessment. The study is focused on an old municipal solid waste sealed landfill site, located in Gaeiras, Central Portugal. The problem is related with leachate overproduction in this domestic and industrial waste landfill that became an environmental problem with urgent assessment, so that a solution could be planned. Due to the lack of accurate information regarding the shape, history and development of the landfill, the use of a set of classical geophysical methods was the option, since they are non-invasive and non-destructive. The available area was small, almost restricted to the landfill area. To conduct this assessment, electromagnetic RF-EM and Geonics EM34, spontaneous potential (SP), vertical electrical soundings (VES) and magnetic prospecting surveys were planned to understand the various problems that could be related with the leachate overproduction. The joint use of these classical geophysical methods was targeted to investigate bedrock depth and structure (RF-EM, EM34 and VES), waste and leachate characteristics (EM34 and magnetics) and groundwater flow (SP) in the landfill. Geophysical results were correlated with hydrogeological information, integrated and interpreted, using geographic information system tools. The results obtained were important to understand the geological mechanisms that are responsible for leachate overproduction and to suggest remedial measures.  相似文献   

Numerical study on the effect of submerged depth on the horizontal plate wave energy converter   总被引：2，自引：0，他引：2  

Flávio Medeiros SEIBT  ;Eduardo Costa COUTO  ;Elizaldo Domingues dos SANTOS  ;Liércio André ISOLDI  ;Luiz Alberto Oliveira ROCHA 《中国海洋工程》2014,28(5):687-700

The growing search for clean and renewable energy sources has given rise to the studies of exploring sea wave energy. This paper is concerned with the numerical evaluation of the main operational principle of a submerged plate employed for the conversion of wave energy into electrical one. The numerical model used to solve the conservation equations of mass, momentum and transport of volume fraction is based on the finite volume method （FVM）. In order to tackle with the flow of mixture of air-water and its interaction with the device, the multiphase model volume of fluid （VOF） is employed. The purpose of this study is the evaluation of a numerical model for improvement of the knowledge about the submerged plate wave energy converter, as well as the investigation of the effect of the distance from the plate to the bottom of the sea （HP） on the performance of the converter. The simulations for several distances of the plate from the seabed show that the optimal efficiency is 64%, which is obtained for HP=0.53 m （88% of the depth）. This efficiency is 17% larger than that found in the worst case （HP=0.46 m, 77% of the depth）.  相似文献   

The surface radiation budget over South America in a set of regional climate models from the CLARIS-LPB project   总被引：1，自引：0，他引：1  

Natalia L. Pessacg  Silvina A. Solman  Patrick Samuelsson  Enrique Sanchez  José Marengo  Laurent Li  Armelle Reca C. Remedio  Rosmeri P. da Rocha  Caroline Mourão  Daniela Jacob 《Climate Dynamics》2014,43(5-6):1221-1239

The performance of seven regional climate models in simulating the radiation and heat fluxes at the surface over South America (SA) is evaluated. Sources of uncertainty and errors are identified. All simulations have been performed in the context of the CLARIS-LPB Project for the period 1990–2008 and are compared with the GEWEX-SRB, CRU, and GLDAS2 dataset and NCEP-NOAA reanalysis. Results showed that most of the models overestimate the net surface short-wave radiation over tropical SA and La Plata Basin and underestimate it over oceanic regions. Errors in the short-wave radiation are mainly associated with uncertainties in the representation of surface albedo and cloud fraction. For the net surface long-wave radiation, model biases are diverse. However, the ensemble mean showed a good agreement with the GEWEX-SRB dataset due to the compensation of individual model biases. Errors in the net surface long-wave radiation can be explained, in a large proportion, by errors in cloud fraction. For some particular models, errors in temperature also contribute to errors in the net long-wave radiation. Analysis of the annual cycle of each component of the energy budget indicates that the RCMs reproduce generally well the main characteristics of the short- and long-wave radiations in terms of timing and amplitude. However, a large spread among models over tropical SA is apparent. The annual cycle of the sensible heat flux showed a strong overestimation in comparison with the reanalysis and GLDAS2 dataset. For the latent heat flux, strong differences between the reanalysis and GLDAS2 are calculated particularly over tropical SA.  相似文献   

Multi-hydro hydrological modelling of a complex peri-urban catchment with storage basins comparing C-band and X-band radar rainfall data     

Bianca Alves de Souza  Igor da Silva Rocha Paz  Abdellah Ichiba  Bernard Willinger  Auguste Gires  Jose Carlos Cesar Amorim 《水文科学杂志》2013,58(11):1619-1635

ABSTRACT

The spread of impervious surfaces in urban areas combined with the rise in the intensity of rainfall events as a result of climate change has led to dangerous increases in storm water flows. This paper discusses a new implementation of the fully distributed hydrological model Multi-Hydro (developed at École des Ponts ParisTech), when operating storage basins, and its ability to deal with high-resolution radar rainfall data. The peri-urban area of Massy (south of Paris, France) was selected as a case study for having six of these drainage facilities, used extensively in flood control. Two radar rainfall datasets with different spatiotemporal resolutions were used: Météo-France’s PANTHER rainfall product (C-band) and ENPC’s X-band DPSRI. The rainfall spatiotemporal variability was analysed statistically using Universal Multifractals (UM). Finally, to validate the application, the water level simulations were compared with local measurements in the Cora storage basin located next to the catchment’s single outlet.  相似文献   

Dynamical evolution of an unstable gravastar with zero mass     

R. Chan  M. F. A. da Silva  Jaime F. Villas?da?Rocha 《Astrophysics and Space Science》2012,337(1):185-191

Using the conventional gravastar model, that is, an object constituted by two components where one of them is a massive infinitely thin shell and the other one is a de Sitter interior spacetime, we physically interpret a solution characterized by a zero Schwarzschild mass. No stable gravastar is formed and it collapses without forming an event horizon, originating what we call a massive non-gravitational object. The most surprise here is that the collapse occurs with an exterior de Sitter vacuum spacetime. This creates an object which does not interact gravitationally with an outside test particle and it may evolve to a point-like topological defect.  相似文献   

A 4D-variational ocean data assimilation application for Santos Basin,Brazil     

Mauricio da Rocha Fragoso  Gabriel Vieira de Carvalho  Felipe Lobo Mendes Soares  Daiane Gracieli Faller  Luiz Paulo de Freitas Assad  Raquel Toste  Lívia Maria Barbosa Sancho  Elisa Nóbrega Passos  Carina Stefoni Böck  Bruna Reis  Luiz Landau  Hernan G. Arango  Andrew M. Moore 《Ocean Dynamics》2016,66(3):419-434

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