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Different Morphological Types (different + morphological_type)
Selected AbstractsCosmic evolution of metal densities: the enrichment of the intergalactic mediumMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2006F. Calura ABSTRACT By means of chemo-photometric models for galaxies of different morphological types, we have carried out a detailed study of the history of element production by spheroidal and dwarf irregular galaxies. Spheroidal galaxies suffer a strong and intense star formation episode at early times. In dwarf irregulars, the star formation rate (SFR) proceeds at a low regime but continuously. Both galactic types enrich the intergalactic medium (IGM) with metals by means of galactic winds. We have assumed that the galaxy number density is fixed and normalized to the value of the optical luminosity function observed in the local Universe. Our models allow us to investigate in detail how the metal fractions locked up in stars in spheroids and dwarf irregulars, those present in the interstellar medium (ISM) and those ejected into the IGM have changed with cosmic time. By relaxing the instantaneous recycling approximation and taking into account stellar lifetimes, for the first time we have studied the evolution of the chemical abundance ratios in the IGM and compared our predictions with a set of observations by various authors. Our results indicate that the bulk of the IGM enrichment is due to spheroids, with dwarf irregular galaxies playing a negligible role. Our predictions grossly account for the [O/H] observed in the IGM at high redshift, but overestimate the [C/H]. Furthermore, it appears hard to reproduce the abundance ratios observed in the high-redshift IGM. Some possible explanations are discussed in the text. This is the first attempt to study the abundance ratios in the IGM by means of detailed chemical evolution models which take into account the stellar lifetimes. Numerical simulations adopting our chemical evolution prescriptions could be useful to improve our understanding of the IGM chemical enrichment. [source] On the evolution of the Fe abundance and of the Type Ia supernova rate in clusters of galaxiesMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY: LETTERS (ELECTRONIC), Issue 1 2007F. Calura ABSTRACT The study of the Fe abundance in the intracluster medium (ICM) provides strong constraints on the integrated star formation history and supernova rate of the cluster galaxies, as well as on the ICM enrichment mechanisms. In this Letter, using chemical evolution models for galaxies of different morphological types, we study the evolution of the Fe content of clusters of galaxies. We assume that the ICM Fe enrichment occurs by means of galactic winds arising from elliptical galaxies and from gas stripped from the progenitors of S0 galaxies via external mechanisms, due to the interaction of the interstellar medium with the ICM. The Fe-rich gas ejected by ellipticals accounts for the XFe,ICM values observed at z > 0.5, whereas the gas stripped from the progenitors of the S0 galaxies accounts for the increase of XFe,ICM observed at z < 0.5. We test two different scenarios for Type Ia supernova (SN) progenitors and we model the Type Ia SN rate observed in clusters, finding a good agreement between our predictions and the available observations. [source] Quantitative determination of cytotoxicFriedo-nor -oleanane derivatives from five morphological types of Maytenus ilicifolia (celastraceae) by reverse-phase high-performance liquid chromatographyPHYTOCHEMICAL ANALYSIS, Issue 2 2002Waldemar Buffa Filho Abstract Five different morphological types of Maytenus ilicifolia of the same age and harvested under the same conditions showed distinct accumulations of some friedo-nor -oleananes. A rapid, sensitive and reliable reverse-phase HPLC method (employing an external standard) was used for the determination of the cytotoxic triterpenoids, 20,-hydroxymaytenin, 22,-hydroxymaytenin, maytenin, celastrol and pristimerin in each of the five types. Well resolved peaks with good detection response and linearity in the range1.0,100,µg/mL were obtained. Copyright © 2002 John Wiley & Sons, Ltd. [source] Glycinergic input of widefield, displaced amacrine cells of the mouse retinaTHE JOURNAL OF PHYSIOLOGY, Issue 15 2009Sriparna Majumdar Glycine receptors (GlyRs) of displaced amacrine cells of the mouse retina were analysed using whole cell recordings and immunocytochemical staining with subunit-specific antibodies. During the recordings the cells were filled with a fluorescent tracer and 11 different morphological types could be identified. The studies were performed in wild-type mice and in mutant mice deficient in the GlyR,1 (Glra1spd-ot, ,oscillator' mouse), the GlyR,2 (Glra2,/,) and the GlyR,3 subunit (Glra3,/,). Based on their responses to the application of exogenous glycine in the retinas of wild-type and mutant mice, the cells were grouped into three major classes: group I cells (comprising the morphological types MA-S5, MA-S1, MA-S1/S5, A17, PA-S1, PA-S5 and WA-S1), group II cells (comprising the morphological types PA-S4, WA-S3 and WA-multi) and ON-starburst cells. For further analysis, spontaneous inhibitory postsynaptic currents (sIPSCs) were measured both in wild-type and mutant mouse retinas. Glycinergic sIPSCs and glycine induced currents of group I cells remained unaltered across wild-type and the three mutant mice (mean decay time constant of sIPSCs, ,,25 ms). Group II cells showed glycinergic sIPSCs and glycine induced currents in wild-type, Glra1spd-ot and Glra3,/, mice (,,25 ms); however, glycinergic currents were absent in group II cells of Glra2,/, mice. Glycine induced currents and sIPSCs recorded from ON-starburst amacrine cells did not differ significantly between wild-type and the mutant mouse retinas (,,50,70 ms). We propose that GlyRs of group II cells are dominated by the ,2 subunit; GlyRs of ON-starburst amacrine cells appear to be dominated by the ,4 subunit. [source] Ordered and chaotic spiral armsASTRONOMISCHE NACHRICHTEN, Issue 9-10 2008P.A. Patsis Abstract The stellar flow at the arms of spiral galaxies is qualitatively different among different morphological types. The stars that reinforce the spiral arms can be either participating in an ordered or in a chaotic flow. Ordered flows are associated with normal (non-barred) spiral galaxies. Typically they are described with precessing ellipses corresponding to stable periodic orbits at successive energies (Jacobi constants). On the contrary, the spiral arms in barred-spiral systems may be supported by stars in chaotic motion. The trajectories of these stars are associated with the invariant manifolds of the unstable Lagrangian points (L1,2). Response and orbital models indicate that this kind of spirals either stop at an azimuth smaller than , /2, or present large gaps at about this angle. Chaotic spirals appear in strong bars having (L1,2) close to the ends of the bar. The arms of barred-spiral systems with corotation away from the end of the bar can be either as in the case of normal spirals, or supported by banana-like orbits surrounding the stable Lagrangian points (L4,5). We find also models combining ordered and chaotic flows. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Seed morphology of Linaria species from eastern Spain: identification of species and taxonomic implicationsBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2001JOSÉ GABRIEL SEGARRA Seed morphology of 15 taxa of Linaria from eastern Spain has been studied using stereoscopic and scanning electron microscopy. Four different morphological types are described according to features of the seed-coat surface. The type that includes winged seeded taxa is divided into three subtypes. Seed morphology of each type and subtype is described, compared, illustrated and discussed according to its taxonomic and biological implications. A key to identify the different species or groups of species is also supplied. 2001 The Linnean Society of London [source] | |||||||||||||