196,577 research outputs found
Spectroscopic ages and metallicities of galaxies
No full textDwarf galaxies are generally faint. To derive their age and metallicity distributions, it is critical to optimize the use of any collected photon. Koleva et al., using full spectrum fitting, have found strong population gradients in some dwarf elliptical galaxies. Here, we show that the population profiles derived with this method are consistent and more precise with those obtained with spectrophotometric indices. This allows studying fainter objects in less telescope time
The Resolved Stellar Populations of M 32
No full textWe present the deepest optical CMD to date of M 32, obtained from HST ACS/HRC images. The dominant feature is the RC, whose CMD location suggests a, mean age between 8 and 10 Gyr for [Fe/H] = -0.2 in M 32. We detect for the first time the RGB and AGB bumps in M 32 which constrain its mean age to be 5-10 Gyr old at 2' from the center. Bright AGB stars indicate the presence of intermediate-age populations. A detected blue component of stars may indicate for the first time the presence of a young stellar population of Gyr in our M 32 field. However, it is likely that the younger stars of this blue plume belong to M 31 rather than to M 32. The fainter stars populating the blue plume indicate the presence of stars not younger than 1 Gyr and/or blue straggler stars in M 32.</p
Structure and reducibility of yttrium-doped cerium dioxide nanoparticles and (111) surface
No full textThis is the final peer-reviewed manuscript accepted for publication in RSC Advances.
Citation of the published version is:
“Structure and reducibility of yttrium-doped cerium dioxide nanoparticles and (111) surface”
Hristiyan A. Aleksandrov, Iskra Z. Koleva, Konstantin M. Neyman, Tatyana T. Tabakova, and Georgi N. Vayssilov
RSC Advances, 2018, 8, 33728–3374
Managing multiple spaces
Full text linkThis paper is about our experiences of space in the Equator project (www.equator.ac.uk), in particular, the way in which multiple spaces, both virtual and physical, can co-exist. By this we mean that people and objects may have locations in and relationships to both physical space and one or more virtual spaces, and that these different spaces together interact to give an overall system behaviour and user experience. The concepts we develop in this chapter are driven partly by practical experience, and partly by previous theoretical work such as the models and taxonomies of spatial context in (Dix et al., 2000), the models for mixed reality boundaries (Koleva et al., 1999) and capturing human spatial understanding exposed in sources such maps, myths and mathematics (Dix, 2000). We are also building on established work on informal reasoning about space from the AI and GIS communities (Grigni et al, 1995; Papadias et al., 1996) similar to Allen’s well known temporal relations (Allen, 1991)
Complement Factor I Is Upregulated in Rat Hepatocytes by Interleukin-6 But Not by Interferon-γ , Interleukin-1β or Tumor Necrosis Factor-α
No full textComplement factor I (FI) is a regulatory serine protease of the complement system which cleaves three peptide bonds in the alpha -chain of C3b and two bonds in the alpha -chain of C4b and thus prevents the assembly of the C3 and C5 convertases. We have investigated the proinflammatory cytokines IL-6, IL-1 beta, TNF-alpha. and IFN-gamma for their potential role in the regulation of FI expression. Of the investigated cytokines, only IL-6 increased the FI-specific RT-PCR signal in isolated hepatocytes, in the two rat hepatoma-derived cell lines FAO and H4IIE or in HUVECs. Quantitative competitive RT-PCR showed an IL-6 induced upregulation of FI-specific mRNA by about ten-fold. These data are in accord with Northern blot analyses in which the FI-mRNA was upregulated by IL-6 between five- and seven-fold. IL-6, but not IL-1 beta, TNF-alpha or IFN-gamma also increased FI-protein levels in cell culture supernatants by about five-fold as determined by a semiquantitative immunoblot using a novel monoclonal antibody specific for rat FI
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
BVOC emissions, photosynthetic characteristics and changes in chloroplast ultrastructure of Platanus orientalis L. exposed to elevated CO2 and high temperature
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
The Origin of Dwarf Early-Type Galaxies in the Virgo Cluster
No full textWe present new medium resolution kinematic data for a sample of 21 dwarf early-type galaxies (dEs) mainly in the Virgo cluster. These data are used to study the origin of the dE population inhabiting rich clusters. Within them we detect two different subpopulations: half of the sample (52%) are rotationally supported and the other half are pressure supported. We also find that the rotationally supported dEs are located in the outer parts of the cluster, present disky morphological shapes and are younger than those pressure supported that are concentrated in the core of the cluster without any underlying structures. Our analysis reveals that the rotationally supported objects have rotation curves similarly shaped to those of star forming galaxies of similar luminosities and follow the Tully-Fisher relation. This is expected if dE galaxies are the descendant of low luminosity star forming systems which recently entered the cluster and lost their gas due to a ram pressure stripping event, quenching their star formation activity and transforming them into quiescent systems, but conserving their angular momentum
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