4,948 research outputs found

    Dynamical analysis of the cluster pair: A3407 + A3408

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    We carried out a dynamical study of the galaxy cluster pair A3407 \& A3408 based on a spectroscopic survey obtained with the 4 meter Blanco telescope at the CTIO, plus 6dF data, and ROSAT All-Sky-Survey. The sample consists of 122 member galaxies brighter than mR=20m_R=20. Our main goal is to probe the galaxy dynamics in this field and verify if the sample constitutes a single galaxy system or corresponds to an ongoing merging process. Statistical tests were applied to clusters members showing that both the composite system A3407 + A3408 as well as each individual cluster have Gaussian velocity distribution. A velocity gradient of 847±114\sim 847\pm 114 km  s1\rm km\;s^{-1} was identified around the principal axis of the projected distribution of galaxies, indicating that the global field may be rotating. Applying the KMM algorithm to the distribution of galaxies we found that the solution with two clusters is better than the single unit solution at the 99\% c.l. This is consistent with the X-ray distribution around this field, which shows no common X-ray halo involving A3407 and A3408. We also estimated virial masses and applied a two-body model to probe the dynamics of the pair. The more likely scenario is that in which the pair is gravitationally bound and probably experiences a collapse phase, with the cluster cores crossing in less than \sim1 h1h^{-1} Gyr, a pre-merger scenario. The complex X-ray morphology, the gas temperature, and some signs of galaxy evolution in A3408 suggests a post-merger scenario, with cores having crossed each other 1.65h1\sim 1.65 h^{-1}Gyr ago, as an alternative solution.Comment: 17 pages, 12 figures, submitted to MNRAS, accepted 2016 May 9. Received 2016 May 9; in original form 2016 April 1

    Slavnov-Taylor identities for noncommutative QED4_4

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    In this work we present an analysis of the one-loop Slavnov-Taylor identities in noncommutative QED4_4. The vectorial fermion-photon and the triple photon vertex functions were studied, with the conclusion that no anomalies arise.Comment: 24 pages, revtex4, v2: typos correcte

    Quantificação da atividade microbiana e qualidade nutricional do solo em plantio adensado de Nim Indiano (Azadirachta indica A. Juss.) no Território de Identidade Bacia do Paramirim - Semi-árido baiano.

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    A introdução do Nim indiano na silvicultura brasileira vem sendo popularizada através de práticas de manejo empíricas. Estudos relacionados à produtividade e impactos ambientais motivados pelo adensamento indiscriminado da cultura ainda são insipientes. Um ponto crítico é a capacidade antimicrobiana e inseticida da Azadiractina, principio ativo extraído da parte aérea como inseticida botânico, no controle de pragas e doenças na agricultura.Em paralelo aconteceram também os seguintes eventos: V Seminário de Pesquisa do Recôncavo da Bahia; V Seminário Estudantil de Pesquisa da UFRB; V Seminário da Pós-Graduação da UFRB; II Seminário Regional de Pesquisa da EBDA; 5ª Jornada Científica da Embrapa Mandioca e Fruticultura; VIII Seminário Estudantil de Pesquisa e Extensão da FAMAM; Semana de Ciência, Tecnologia e Inovação no Agronegócio; Fórum de Gestores de Iniciação Científica e Tecnológica da Bahia; II Simpósio Baiano de Defesa Agropecuária; I Semana de Educação Tutorial da UFRB

    C and N Abundances in Stars At the Base of the Red Giant Branch in M5

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    We present an analysis of a large sample of moderate resolution Keck LRIS spectra of subgiant (V \sim 17.2) and fainter stars in the Galactic globular cluster M5 (NGC 5904) with the goal of deriving C and N abundances. Star-to-star stochastic variations with significant range in both [C/Fe] and [N/Fe] are found at all luminosities extending to the bottom of the RGB at M_V \sim +3. Similar variations in CH appear to be present in the main sequence turnoff spectra. There is no sign of a change in the behavior of C and N with evolutionary stage over the full range in luminosity of the RGB and SGB. The C and N abundances appear strongly anti-correlated, as would be expected from the CN-cycle processing of stellar material. Yet the present stars are considerably fainter than the RGB bump, the point at which deep mixing is believed to set in. On this basis, while the observed abundance pattern is consistent with proton capture nucleosynthesis, we infer that the site of the reactions is likely not within the present sample, but rather in a population of more massive (2 -- 5 M(Sun)) now defunct stars. The range of variation of the N abundances is very large and the sum of C+N increases as C decreases. To reproduce this requires the incorporation not only of CN but also of ON-processed material. Furthermore, the existence of this correlation is quite difficult to reproduce with an external mechanism such as ``pollution'' with material processed in a more massive AGB star, which mechanism is fundamentally stochastic in nature. We therefore suggest that although the internal mixing hypothesis has serious flaws,new theoretical insights are needed and it should not be ruled out yet. (abridged)Comment: Slightly updated version to conform to that accepted by the A

    Notas sobre o comportamento de corte de Aplastodiscus arildae (Cruz & Peixoto, 1985) em um fragmento florestal urbano no sudeste do Brasil (Amphibia, Anura, Hylidae)

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    The courtship behavior, advertisement call, and courtship call of Aplastodiscus arildae are described based on observations realized at Parque das Mangabeiras, Belo Horizonte, Minas Gerais, Southeastern Brazil. Calling males were observed at leaves above the stream or on the litter near rivulet banks approximately all year. Female is attracted by the calling male and conducted to the subterranean nest, a different place from the calling site. The courtship event involves alternated mutual touches by the couple and calls with higher repetition rate emitted by the male. Aplastodiscus arildae presents reproductive mode with aquatic eggs deposited in subterranean nests. The advertisement call and courtship call consisted of a sequence of a unique no pulsed note, but the first presents larger interval among the calls and duration and higher dominant frequency than the last.O comportamento de corte e os cantos de anúncio e de corte de Aplastodiscus arildae são descritos com base em observações realizadas no Parque das Mangabeiras, Belo Horizonte, Minas Gerais, Sudeste do Brasil. Machos vocalizam praticamente por todo o ano, utilizando como sítios de vocalização a vegetação marginal ou o folhedo no barranco na margem de riachos. A fêmea é atraída pelo macho vocalizante, que a leva até o ninho (uma toca subterrânea), que se situa em local diferente do sítio de vocalização. No processo de condução ao ninho estão envolvidos toques mútuos entre os indivíduos e emissões de canto de corte emitidas pelo macho. Aplastodiscus arildae apresenta modo reprodutivo com ovos aquáticos depositados em ninhos subterrâneos. Os cantos de anúncio e de corte consistem de seqüências de uma única nota não pulsionada, sendo que o primeiro apresenta maior intervalo entre cantos e duração e freqüência dominante mais elevada que o segundo

    Thorium content in soil, water and sediment samples and fluvial sediment-associated transport in a catchment system with a semi-arid interface, Brazil

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    Thorium (Th) is one of the main sources of natural radiation to ecosystems. However, data regarding Th concentrations in rocks, soil, water and sediments are currently scarce. Accordingly, this study aimed to establish background concentrations and quality reference values (QRVs) for Th in the environmentally impacted Ipojuca River catchment in Brazil, where the weathering of granites releases Th into the environment. Additionally, the study aimed to calculate Th fluxes in water, and both bed and suspended sediment. The mean Th concentration in the study catchment soils was 28.6 mg kg−1. The QRV for Th was estimated to be 21 mg kg−1 and 86.3 Bq kg−1. Bed and suspended sediment–associated concentrations ranged from 2.8 to 32.9 mg kg−1. Suspended sediment–associated discharge (3.42 t year−1) accounted for more than 99% of the total Th flux, while the dissolved phase transport was negligible in comparison. At the downstream cross section in the study catchment, suspended sediment samples exhibited Th concentrations similar to those observed in rivers impacted by mining activities. The discharge of sediment to the ocean from the study area is mainly triggered by soil erosion processes in the hotspot region (middle-inferior course). It is essential to identify Th hotspots before establishing environmental policies regarding human health and environmental protection
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