6,294 research outputs found

    NOVO REGISTRO DE FABACEAE (CAESALPINIOIDEAE) PARA O BRASIL: Dimorphandra davisii SPRAGUE & SANDWITH

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    The study presents the first occurrence of Dimorphandra davisii Sprague & Sandwith from Brazil, a species previously known only in Guyana and Venezuela. After examining the INPA and NY herbarium collections, it was verified that the species was collected in 1986 and occurs in the municipality of Presidente Figueiredo, in the state of Amazonas, but never registered for the Brazilian flora. The record of the species increases the floristic data of the Brazilian Amazon and contributes to the better knowledge of Dimorphandra in Brazil.Keywords: Caesalpinieae; Distribution of species; Amazon Rainforest; Taxonomy.O estudo apresenta a primeira ocorrência de Dimorphandra davisii Sprague et Sandwith do Brasil, uma espécie conhecida apenas na Guiana e Venezuela. Depois de examinar as coleções dos herbários INPA e NY, verificou-se que a espécie foi coletada em 1986 e ocorre no município de Presidente Figueiredo, no estado do Amazonas, mas nunca registrada para a flora brasileira. O registro da espécie aumenta os dados florísticos da Amazônia brasileira e contribui para o melhor conhecimento de Dimorphandra no Brasil.Palavras-chave: Caesalpinieae, Distribuição de espécies, Floresta Amazônica, Taxonomia

    How to distinguish starbursts and quiescently star-forming galaxies: The `bimodal' submillimetre galaxy population as a case study

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    In recent work (arXiv:1101.0002) we have suggested that the high-redshift (z ~ 2-4) bright submillimetre galaxy (SMG) population is heterogeneous, with major mergers contributing both at early stages, where quiescently star-forming discs are blended into one submm source (`galaxy-pair SMGs'), and late stages, where mutual tidal torques drive gas inflows and cause strong starbursts. Here we combine hydrodynamic simulations of major mergers with 3-D dust radiative transfer calculations to determine observational diagnostics that can distinguish between quiescently star-forming SMGs and starburst SMGs via integrated data alone. We fit the far-IR SEDs of the simulated galaxies with the optically thin single-temperature modified blackbody, the full form of the single-temperature modified blackbody, and a power-law temperature-distribution model. The effective dust temperature, T_dust, and power-law index of the dust emissivity in the far-IR, \beta, derived can significantly depend on the fitting form used, and the intrinsic \beta\ of the dust is not recovered. However, for all forms used here, there is a T_dust above which almost all simulated galaxies are starbursts, so a T_dust cut is very effective at selecting starbursts. Simulated merger-induced starbursts also have higher L_IR/M_gas and L_IR/L_FUV than quiescently star-forming galaxies and lie above the star formation rate-stellar mass relation. These diagnostics can be used to test our claim that the SMG population is heterogeneous and to observationally determine what star formation mode dominates a given galaxy population. We comment on applicability of these diagnostics to ULIRGs that would not be selected as SMGs. These `hot-dust ULIRGs' are typically starburst galaxies lower in mass than SMGs, but they can also simply be SMGs observed from a different viewing angle.Comment: 21 pages, 11 figures. Accepted for publication in MNRAS. Minor changes to text but otherwise identical to v

    An Ontology for Description of Drug Discovery Investigations

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    SummaryThe paper presents an ontology for the description of Drug Discovery Investigation (DDI). This has been developed through the use of a Robot Scientist “Eve”, and in consultation with industry. DDI aims to define the principle entities and the relations in the research and development phase of the drug discovery pipeline. DDI is highly transferable and extendable due to its adherence to accepted standards, and compliance with existing ontology resources. This enables DDI to be integrated with such related ontologies as the Vaccine Ontology, the Advancing Clinico-Genomic Trials on Cancer Master Ontology, etc. DDI is available at http://purl.org/ddi/wikipedia or http://purl.org/ddi/home</jats:p

    Are chimpanzees really so poor at understanding imperative pointing? Some new data and an alternative view of canine and ape social cognition

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    There is considerable interest in comparative research on different species’ abilities to respond to human communicative cues such as gaze and pointing. It has been reported that some canines perform significantly better than monkeys and apes on tasks requiring the comprehension of either declarative or imperative pointing and these differences have been attributed to domestication in dogs. Here we tested a sample of chimpanzees on a task requiring comprehension of an imperative request and show that, though there are considerable individual differences, the performance by the apes rival those reported in pet dogs. We suggest that small differences in methodology can have a pronounced influence on performance on these types of tasks. We further suggest that basic differences in subject sampling, subject recruitment and rearing experiences have resulted in a skewed representation of canine abilities compared to those of monkeys and apes

    The Moment of Inertia and the Scissors Mode of a Bose-condensed Gas

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    We relate the frequency of the scissors mode to the moment of inertia of a trapped Bose gas at finite temperature in a semi-classical approximation. We apply these theoretical results to the data obtained in our previous study of the properties of the scissors mode of a trapped Bose-Einstein condensate of 87^{87}Rb atoms as a function of the temperature. The frequency shifts that we measured show quenching of the moment of inertia of the Bose gas at temperatures below the transition temperature - the system has a lower moment of inertia that of a rigid body with the same mass distribution, because of superfluidity.Comment: 14 pages, 5 fig

    Molecular basis of structure and function of the microvillus membrane of intestinal epithelial cells

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    Correlation of molecular structure with biochemical functions of the plasma membrane of the microvilli of intestinal epithelial cells has been investigated by biochemical and electron microscopic procedures. Repeating particles, measuring approximately 60 &#197;in diameter, were found on the surface of the microvilli membrane which had been isolated or purified from rabbit intestinal epithelial cells and negatively stained with phosphotungstic acid. These particles were proved to be inherent components of the microvillus membrane, attached to the outer surface of its trilaminar structure, and were designated as the elementary particles of the microvilli of intestinal epithelial cells. Biochemical and electron microscopic identification of these elementary particles has been carried out by isolation of the elementary particles with papain from the isolated microvillus membrane, followed by purification of the particles by chromatographies on DEAE-cellulose and Sephadex columns. The partially purified particles containing invertase and leucine aminopeptidase are similar in size and structure to those of the elementary particles in the microvillus membrane. Evidence indicates that each of the elementary particles coincide with or include an enzyme molecule such as disaccharidase or peptidase, which carry out the terminal hydrolytic digestion of carbohydrates and proteins, respectively, on the surface of the microvillus membrane. Magnesium ionactivated adenosine triphosphatase and alkaline phosphatase cannot be solubilized with papain but remains in the smooth-surface membrane after the elementary particles have been removed. Cytochemical electron microscopic observation revealed that the active site of magnesium ion-activated adenosine triphosphatase is localized predominantly in the inner surface of the trilaminar structure of the microvillus membrane.</p

    X-ray selected AGN in groups at redshifts z~1

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    We explore the role of the group environment in the evolution of AGN at the redshift interval 0.7<z<1.4, by combining deep Chandra observations with extensive optical spectroscopy from the All-wavelength Extended Groth strip International Survey (AEGIS). The sample consists of 3902 optical sources and 71 X-ray AGN. Compared to the overall optically selected galaxy population, X-ray AGN are more frequently found in groups at the 99% confidence level. This is partly because AGN are hosted by red luminous galaxies, which are known to reside, on average, in dense environments. Relative to these sources, the excess of X-ray AGN in groups is significant at the 91% level only. Restricting the sample to 0.7<z<0.9 and M_B<-20mag in order to control systematics we find that X-ray AGN represent (4.7\pm1.6) and (4.5\pm1.0)% of the optical galaxy population in groups and in the field respectively. These numbers are consistent with the AGN fraction in low redshift clusters, groups and the field. The results above, although affected by small number statistics, suggest that X-ray AGN are spread over a range of environments, from groups to the field, once the properties of their hosts (e.g. colour, luminosity) are accounted for. There is also tentative evidence, significant at the 98% level, that the field produces more X-ray luminous AGN compared to groups, extending similar results at low redshift to z~1. This trend may be because of either cold gas availability or the nature of the interactions occurring in the denser group environment (i.e. prolonged tidal encounters).Comment: To appear in MNRA

    The clustering of X-ray selected AGN at z=0.1

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    The clustering properties of moderate luminosity (LX=10411044ergs1L_X = \rm 10^{41} - 10^{44} \, erg \,s^{-1}) X-ray selected AGN at z0.1z\approx0.1 are explored. X-ray sources in the redshift interval 0.03<z<0.20.03<z<0.2 are selected from a serendipitous XMM survey of the SDSS footprint (XMM/SDSS) and are cross-correlated with the SDSS Main galaxy sample. The inferred X-ray AGN auto-correlation function is described by a power law with amplitude r05r_0\approx5\,h1^{-1}Mpc and slope γ2.0\gamma\approx2.0. The corresponding mass of the dark matter haloes that host X-ray AGN at z0.1z\approx0.1 is \approx 10^{13} \,h ^{-1} \, M_{\sun}. Comparison with studies at higher redshift shows that this mass scale is characteristic of moderate luminosity X-ray AGN out to z1z\approx 1. Splitting the AGN sample by rest-frame color shows that X-ray sources in red hosts are more clustered than those associated with blue galaxies, in agreement with results at z1z\approx1. We also find that the host galaxies of X-ray AGN have lower stellar masses compared to the typical central galaxy of a \approx 10^{13} \,h ^{-1} \, M_{\sun} dark matter halo. AGN hosts either have experienced less stellar mass growth compared to the average central galaxy of a \approx 10^{13} \,h ^{-1} \, M_{\sun} halo or a fraction of them are associated with satellite galaxies.Comment: MNRAS accepted 14 pages, 8 figures, 5 table
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