92,701 research outputs found

    Bioerosive structures of sclerozoan foraminifera from the lower pliocene of southern Spain: a contribution to the palaeoecology of marine hard substrate communities

    Get PDF
    A palaeoecological study of sclerozoan foraminifera of the families Saccamminidae (aff. Sagenina), Lituolidae (Placopsilina), Cibicididae (Cibicides, Dyocibicides, Cibicidella) and Planorbulinidae (Planorbulina and Planorbulinella) that colonized epifaunal bivalves (ostreids and pectinids) during the early Pliocene in southern Spain has led to the recognition of two new boring ichnogenera: Camarichnus ichnogen. nov., with two ichnospecies, C. subrectangularis ichnosp. nov. and C. arcuatus ichnosp. nov., and Canalichnus ichnogen. nov., with one ichnospecies, C. tenuis ichnosp. nov. The first two ichnospecies were produced by adnate lituolids and cibicidids, the last by saccamminids. Their recognition is very important when quantifying populations of these organisms. Colonisation took place after death of the host bivalves, when they acted as very stable substrates whose topography probably controlled the initial settlement pattern of the foraminifera. The colonisation sequence started with the foraminifera (lituolids-saccamminids-cibicidids-planorbulinids) and was followed by vermetid gastropods, serpulids, spirorbids, cheilostome bryozoans and/or ostreids. Preferred orientations and over-growth relationships between cheilostome bryozoans and serpulids have been detected in this material.info:eu-repo/semantics/publishedVersio

    Monte Carlo simulation of a hard-sphere gas in the planar Fourier flow with a gravity field

    Full text link
    By means of the Direct Simulation Monte Carlo method, the Boltzmann equation is numerically solved for a gas of hard spheres enclosed between two parallel plates kept at different temperatures and subject to the action of a gravity field normal to the plates. The profiles of pressure, density, temperature and heat flux are seen to be quite sensitive to the value of the gravity acceleration gg. If the gravity field and the heat flux are parallel (g>0g>0), the magnitudes of both the temperature gradient and the heat flux are smaller than in the opposite case (g<0g<0). When considering the actual heat flux relative to the value predicted by the Fourier law, it is seen that, if g>0g>0, the ratio increases as the reduced local field strength increases, while the opposite happens if g<0g<0. The simulation results are compared with theoretical predictions for Maxwell moleculesComment: 18 pages (LaTex), 7 figures (eps

    A Synopsis of Bolivian Polyrhaphis Audinet-Serville (Coleoptera, Cerambycidae, Lamiinae) with description of a new species

    Get PDF
    The Bolivian species of Polyrhaphis Audinet-Serville, 1835, (Coleoptera, Cerambycidae, Lamiinae) are reviewed and illustrated, with P. skillmani new species described. A key is presented to the six species recorded from Bolivia (P. angustata Buquet, 1853; P. argentina Lane, 1978; P. gracilis Bates, 1862; P. pilosa Lane, 1965; P. spinosa (Drury, 1773); and P. skillmani Wappes and Santos-Silva, new species). Their collection localities, based on recently identified specimens examined by the authors, are plotted to show the distribution of species, and displayed next to an ecoregion map of Bolivia to illustrate biogeographical information for Polyrhaphis.Se revisan e ilustran las especies bolivianas de Polyrhaphis Audinet-Serville, 1835, (Coleoptera, Cerambycidae, Lamiinae) con la descripción de P. skillmani especie nueva. Se presenta una clave para las seis especies conocidas de Bolivia (P. angustata Buquet, 1853; P. argentina Lane, 1978; P. gracilis Bates, 1862; P. pilosa Lane, 1965; P. spinosa (Drury, 1773); y P. skillmani Wappes y Santos-Silva especie nueva). Se trazan sobre un mapa las localidades de colecta, basadas en especímenes identificados recientemente y examinados por los autores, y se muestran junto a un mapa de las ecorregiones de Bolivia para ilustrar la información biogeográfica de Polyrhaphis

    Descriptions of females of Nothopleurus Lacordaire and Strongylaspis Thomson (Coleoptera: Cerambycidae: Prioninae: Macrotomini) with new distributional records

    Get PDF
    The female of Nothopleurus subsulcatus (Dalman, 1823) (Coleoptera: Cerambycidae: Prioninae: Macrotomini) is described for the first time, and the female of Strongylaspis bullata Bates, 1872 is redescribed. Color photographs of the habitus of both, and key characters for the former are included. New distributional records within Mexico for N. subsulcatus and Strongylaspis championi Bates, 1884 are given.A fêmea de Nothopleurus subsulcatus (Dalman, 1823) (Coleoptera: Cerambycidae: Prioninae: Macrotomini) é descrita pela primeira vez e a de Strongylaspis bullata Bates, 1872 é redescrita. São adicionadas figuras coloridas para as duas espécies e chave parcial para a N. subsulcatus. São fornecidos novos registros no México para N. subsulcatus e Strongylaspis championi Bates, 1884
    corecore