bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of oxygen and growth medium onin vitrobiofilm formation byEscherichia coli
Authors: Bjergbæk L. A. , Haagensen J. A. J. , Reisner A. , Molin S. , Roslev P. 
Published: April 2007

ABSTRACTThe effects of oxygen availability onin vitrobiofilm formation by anEscherichia coliK-12 strain and 13 clinicalE. colistrains were compared. AllE. colistrains were capable of forming monospecies biofilm on polystyrene in aerobic media. The K-12 strain produced biofilm in both aerobic glucose minimal medium (ABTG), and aerobic trypticase soy broth (TSB) whereas the majority of the clinical strains produced significant biofilm only in aerobic TSB (9 of 13). In anaerobic media,E. coliK-12 and 9 of the 13 clinical strains were capable of forming biofilmin vitro. Only three clinical strains formed biofilm in anaerobic TSB whereas six clinical strains produced detectable biofilm in anaerobic ABTG. None of the strains tested were capable of forming biofilm in both anaerobic ABTG and anaerobic TSB. Strains that were good biofilm formers in aerobic ABTG also produced the highest amount of biofilm in anaerobic ABTG (R2= 0.90). Image analysis revealed notable differences in architecture for biofilms grown in the presence and in the absence of oxygen. In aerobic ABTG, the biofilm was dominated by tall, mushroom-shaped microcolonies with pores and channels whereas biofilm in anaerobic ABTG was thinner and less heterogeneous, resulting in reduced maximum thickness and biovolume. Analysis of phospholipid fatty acid (PLFA) profiles fromE. coliK-12 and three clinical strains did not reveal a specific pattern associated with the biofilm phenotypes. Interestingly, the clinicalE. colistrains adjusted their PLFA composition much more than didE. coliK-12 in response to changes in growth regimens. Collectively, the results indicate that oxygen availability may affectE. colibiofilm formation in minimal and complex media. The results confirm thatE. coliK-12 and some clinicalE. colistrains are capable of formingin vitrobiofilm under anaerobic conditions. However, the data also suggest that this attribute is highly strain dependent and may vary significantly among clinical isolates.
Spheroids scaling relations over cosmic time
Authors: Treu Tommaso 
Published: April 2007

AbstractI report on recent measurements of two scaling relations of spheroids in the distant universe, the Fundamental Plane, and the relation between lensing velocity dispersion and stellar velocity dispersion. The joint analysis of the two scaling relations indicates that the most massive (above ~1011.5M⊙) spheroids are consistent with no evolution since z ~ 1 both in terms of star formation and internal structure. Furthermore their total mass density profile is on average well described by an isothermal sphere with no evidence for redshift evolution. At smaller masses the picture appears to be substantially different, as indicated by evidence for substantial recent star formation (as much as 20–40% of stellar mass formed since z ~ 1), and by hints of a reduced dark matter content at smaller masses. A larger sample of lenses extending to velocity dispersions below 200\kms, and to redshifts above >0.5 is needed to verify these trends.
The Millennium Galaxy Catalogue: Galaxy Bimodality
Authors: Driver Simon P. , Liske Jochen , Graham Alister W. 
Published: April 2007

AbstractGalaxy bimodality is caused by the bulge-disc nature of galaxies as opposed to two distinct galaxy classes. This is evident in the colour-structure plane which clearly shows that elliptical galaxies (bulge-only) lie in the red compact peak and late-type spiral galaxies (disc-dominated) lie in the blue diffuse peak. Early-type spirals (bulge plus disc systems) sprawl across both peaks. However after bulge-disc decomposition the bulges of early-type spirals lie exclusively in the red compact peak and their discs in the blue diffuse peak (exceptions exist but are rare, e.g., dust reddened edge-on discs and blue pseudo-bulges). Movement between these two peaks is not trivial because whilst switching off star-formation can transform colours from blue to red, modifying the orbits of ~1 billion stars from a planar diffuse structure to a triaxial compact structure is problematic (essentially requiring an equal mass merger). We propose that the most plausible explanation for the dual structure of galaxies is that galaxy formation proceeds in two stages. First an initial collapse phase (forming a centrally concentrated core and black hole), followed by splashback, infall and accretion (forming a planar rotating disc). Dwarf systems coule perhaps follow the same scenario but the lack of low luminosity bulge-disc systems would imply that the two components must rapidly blend to form a single flattened spheroidal system.
Secular evolution in galaxies
Authors: Combes F. 
Published: April 2007

AbstractNew observations in favour of a significant role of secular evolution are reviewed: central star formation boosted in pseudo-bulge barred galaxies, relations between bulge and disk, evidence for rejuvenated bulges. Numerical simulations have shown that secular evolution can occur through a cycle of bar formation and destruction, in which the gas plays a major role. Since bars are weakened or destroyed in gaseous disks, the high frequency of bars observed today requires external cold gas accretion, to replenish the disk and allow a new bar formation. The rate of gas accretion from external filaments is compatible with what is observed in cosmological simulations.
The Building of Galactic Disks: Insights from the Triangulum Spiral Galaxy Messier 33
Authors: Block David L. , Puerari Ivânio , Fazio Giovanni G. , Stockton Alan , Canalizo Gabriela , Freeman Kenneth C. , Jarrett Thomas H. , Combes Françoise , Groess Robert , Worthey Guy , Gehrz Robert D. , Woodward Charles E. , Polomski Elisha F. 
Published: April 2007

AbstractThe Triangulum Spiral Galaxy Messier 33 offers unique insights into the building of a galactic disk. We identify spectacular arcs of intermediate age (0.6 Gyr − 2 Gyr) stars in the low-metallicity outer disk. The northern arc spans ~120 degrees in azimuth and up to 5 arcmin in width. The arcs are located 2-3 disk scale lengths from the galaxy centre (where 1 disk scale length is equivalent to 0.1 degrees in the V-band) and lie precisely where there is a warp in the HI profile of M33. Warps and infall are inextricably linked (Binney, 1992). We present spectroscopy of candidate stars in the outer northern arc, secured using the Keck I telescope in Hawaii. The target stars have estimated visual magnitudes as faint as V~ 25m. Absorption bands of CN are seen in all spectra reported in this review talk, confirming their carbon star status. Also presented are PAH emissivity radial profiles generated from IRAC observations of M33 using the Spitzer Space Telescope. A dramatic change of phase in the m = 2 Fourier component is detected at the domain of the arcs. M33 serves as an excellent example how the disks of spiral galaxies in our Universe are built: as dynamically open systems, growing from the inward, outward.
B/T-ratios in the Hubble sequence
Authors: Laurikainen Eija , Salo H. , Buta R. , Knapen J. H. , Speltincx T. , Block D. L. 
Published: April 2007

AbstractWe discuss bulges in the Hubble sequence, based on the analysis of deep near-IR images for a sample of 216 nearby galaxies. Using a 2D multicomponent decomposition code, we find that the average bulge-to-total (B/T) flux ratio is less than 0.25 across all morphological types. Even 50% of the early-type galaxies (S0-S0/a) are found to have nuclear bars, inner disks or nuclear rings inside the bulge. Also, the shape parameter of the bulge is on average ≤2 for all Hubble types. Our results are consistent with the picture in which bulges even in many early-type galaxies were formed by secular evolutionary processes. We find two galaxies that might be stripped spirals, belonging to the so far empty S0c morphological class introduced by van den Bergh (1979).
Establishing the relationship between galaxies and dark matter
Authors: Mo H. J. , Yang X.H. , van den Bosch F.C. , Jing Y.P. , Weinmann S.M. 
Published: April 2007

AbstractWe use two methods to establish the relationship between galaxies and dark matter halos. One is based the conditional luminosity function model, which links galaxies and dark matter halos by matching the number density and clustering properties of galaxies with those of dark matter halos in the current CDM model. The second is based on galaxy systems identified from large redshift surveys of galaxies. The galaxy – dark halo relationships established by these two methods match well, and can provide important constraints on how galaxies form and evolve in the universe.
From nuclear clusters to halo globulars: Star clusters as basic galactic building blocks
Authors: de Grijs Richard 
Published: April 2007

AbstractI assess the similarities and differences between the star-formation modes in quiescent spiral galaxies versus those in violent starburst regions, including galactic nuclei. As opposed to the quiescent star-formation mode, current empirical evidence on the star-formation processes in the extreme, high-pressure environments induced by galaxy encounters strongly suggests that star cluster formation is an important and perhaps even the dominant mode of star formation in such starburst events. This implies that by using star clusters as unique diagnostic probes, we can trace a galaxy's most violent star formation history very well, at least for the past few Gyr. The sizes, luminosities, and mass estimates of the young massive star clusters are entirely consistent with what is expected for young Milky Way-type globular clusters (GCs). Recent evidence lends support to the scenario that GCs, which were once thought to be the oldest building blocks of galaxies, are still forming today.
IZw18, or The Picture of Dorian Gray: The More You Watch it, The Older it Gets
Authors: Tosi M. , Aloisi A. , Mack J. , Maio M. 
Published: April 2007

AbstractIZw18 has been recurrently claimed to be a young galaxy, but stars of increasingly older ages are found every time deeper magnitude levels are reached with high-resolution photometry: from the original few Myrs to, possibly, several Gyrs. We summarize the history of IZw18's age and an HST project which will allow us to derive both its distance and age.
A Titius-Bode like law for stellar populations in the velocity space
Authors: Alcobé Santiago , Cubarsi Rafael 
Published: April 2007

AbstractThe statistical algorithm MEMPHIS (Cubarsi & Alcobé 2006) was applied to a large sample from the Hipparcos catalogue with the full space motions (Cubarsi & Alcobé 2004), to segregate the kinematic populations of the solar neighbourhood. Four stellar populations were obtained, namely early-thin disk, young-thin disk, the whole thin disk (which contains both previous populations plus the continuum of old thin disk stars), and the thick disk population. Now, we wish to point out two main results from the analysis of such a segregation (Alcobé & Cubarsi 2005). First, the relationship between the maximum stellar velocity of a sample and its average age τ can be approximated by the relation |V|max ∝ τ. Second, the local stellar populations can be described from a Titius-Bode like law (TBLL) for the radial velocity dispersion, $\sigma_1 = 6.6 \, (\frac43)^n$, so that for values n = 2, 3, 5, 8 it determines some average energy levels of discrete populations, while for continuous intervals n ≤ 5 and n ≥ 7 it describes the velocity-age evolution of thin and thick disk components, as shown in the Table below.Thus, the velocity dispersions of the local kinematic populations seem to follow a geometrical progression, allowing us to do an analogy with the old Titius-Bode distribution for keplerian orbits, although a physical explanation for the later law remains still open (Lynch 2003). Indeed, such a TBLL in the velocity space could be already conjectured from previous published kinematic parameters of the Galactic components (e.g. Alcobé & Cubarsi 2001). As in the keplerian case, it is possible to argue that velocity dispersion values have too much uncertainty, but, even so, it is not possible to ignore anymore such a resemblance.Such results are consistent with Galactic formation models that predict some quasi-continuous stellar populations in the sense that the continuity is constricted by σ1 levels of the TBLL. The physical meaning of the variable n involved in the TBLL may be related with the average epicycle energy ER ~ σ21 of the stars representative of the disk heating process. It shows continuity from n = 3 to 5 for the thin disk, and from 7 to 8 for the thick disk, but discreteness from n = 2 to 3 between early-thin and young-thin disk, and from 5 to 8 between thin and thick disk components. For the thin disk, for example, the level n = 5 should represent the saturation point of maximum velocity dispersion, likely corresponding to the limited predicted by the observed wavenumber of spiral structure of the Milky Way, while the discontinuity from n = 5 to 7 indicates an abrupt jump in the average energy, that was produced when the thick disk was formed about 10±1 Gyr ago.
Physical Properties of Nearby Dwarf Elliptical Galaxies
Authors: Seo M. R. , Ann H. B. 
Published: April 2007

AbstractMost dwarf elliptical galaxies except for ‘dE, N’ galaxies which are characterized by young stellar populations in the nuclear regions are located in the high density environment. The colors and spectra of ‘dE, N’ galaxies are different from other types, in the sense that they have redder colors with little emission lines. The majority of dwarf elliptical galaxies are younger than 7 Gyr with metallicity larger than [z/H]=−0.5.
New HST/ACS Observations of Dwarf Star-Forming Galaxies with Extreme Properties of Cosmological Relevance
Authors: Annibali F. , Aloisi A. , Van der Marel R. , Mack J. , Tosi M. 
Published: April 2007

AbstractWe present deep Color Magnitude Diagrams (CMDs), based on HST/ACS data, of two star-forming dwarf galaxies, NGC4449 and IZw18.
Stellar Populations and Kinematics in Seyfert Galaxies
Authors: Asari N. V. , Vega L. R. , Garcia-Rissmann A. , González Delgado R. M. , Storchi-Bergmann T. , Cid Fernandes R. 
Published: April 2007

AbstractOur aim is to study the stellar kinematics in hosts of AGN. We do so by measuring nuclear stellar velocity dispersions (σ⋆). Our sample comprises spectra of 78 objects, 69 of which are Seyfert galaxies, in the region around the λλ8498.02, 8542.09, 8662.14 Calcium triplet (CaT). We investigate two methods to measure σ⋆: (1) the direct fitting method (DFM), which makes use of our stellar population synthesis code Starlight, and (2) the cross-correlation method (CCM), for which we use the fxcor package in IRAF. Both methods yield velocity dispersions consistent to within 19 km/s on-average. We have also measured the CaT equivalent width (WCaT) and the λ3933 CaII K equivalent width (WK) for the objects in our sample. Other studies have shown that WK is a powerful tracer of starbursts in Seyfert nuclei, so we check if WCaT can be used in the same way. We have also analysed a sub-sample of 34 spatially resolved objects with reasonably good off-nuclear signal-to-noise. We study the spatial variations of both σ⋆ and WCaT. We see no dilution in WCaT for composite starburst + Seyfert 2 galaxies, in contrast to the dilution in the WK (studied by other authors) for the same objects.
Test of Clausius' Virial Dynamical Theory of Fundamental Plane By Homogeneous + γ-Free Two Component Galaxy Model
Authors: Bindoni D. , Secco L. , Caimmi R. , D'Onofrio M. , Valentinuzzi T. 
Published: April 2007

AbstractTo test the extension of the theory of the Fundamental Plane (FP) proposed by Secco (2000, 2001, 2005) to an higher order (non-linear) we explore the effect on an homogeneous stellar component due to a DM halo with a density profile characterized by an inner slope γ free and an outer slope −3, according to high resolution RCs of Sps (Garrido et al., 2004). The aim is to investigate the role of the dark to bright mass ratio m and of the halo concentration CD in order to produce the maximum of Clausius' Virial potential energy (CV). Particular attention is devoted to the slope of the density halo profile at the maximum location, to its height in comparison with the CV value when the two components coincide, Vn. For all models we choose γ = 0. We follow the general method proposed by Caimmi, 1993 for two striated ellipsoidals with Zhao-density profiles. Virial equilibrium is described by tensor virial equations extended to two components (Caimmi & Secco, 1992). Sequences of CV as function of the ratio baryonic to halo virial semi-axis, numerically performed for different values of m and CD, are taken into account.
Figure Rotation of Dark Halos in Cold Dark Matter Simulations
Authors: Bryan S.E. , Cress C.M. 
Published: April 2007

AbstractWe investigate the rotation of dark matter halos identified in ΛCDM simulations. After removing halos that contain a significant amount of substructure, about 82% of the remaining halos were found to undergo coherent rotation over 5h−1 Gyr. The rotation speeds follow a log-normal distribution. The average rotation speed of a halo was 0.11h rads/Gyr. Less than half of the selected halos showed alignment between their rotation and minor axes. We found no correlation between halo properties, such as total mass, and the rotation speed.
The Distribution of Bar Strengths in Disk Galaxies
Authors: Buta R. , Laurikainen E. , Salo H. , Knapen J. H. , Block D. L. 
Published: April 2007

AbstractBars are the most important features that redistribute angular momentum and drive secular evolution in disk galaxies. We have derived the distribution of bar strengths in spirals and the Fourier properties of early-type galaxy bars in order to evaluate recent models of bar-halo angular momentum transfer and external gas accretion. A few results are presented here.
Edge-on Low Surface Brightness Galaxies in the SDSS and the Red Halo Phenomenon
Authors: Caldwell Brady , Bergvall Nils 
Published: April 2007

AbstractExtremely red halos have been detected around high surface brightness (HSB) disk galaxies and blue compact galaxies. We analyse the halo emission of a sample of 970 stacked edge-on low surface brightness (LSB) galaxies in the SDSS (DR4) down to μg ~ 30 mag arcsec−2. These are divided by g − r colour limits into a “blue” Sample A (336 galaxies), “yellow” Sample B (318 galaxies) and “red” Sample C (316 galaxies). The gri colours indicate a prominent red excess in the polar direction, strongly deviating from any normal stellar population.
The Many Vortexes of NGC 5236 Nucleus in The Central 80×200 Parsecs
Authors: Diaz R. , Rodrigues I. , Dottori H. , Mast D. , Agüero M. P. 
Published: April 2007

AbstractGEMINI-S+CIRPASS configuration has been used to obtain 490 high quality spectra, centred in 1.3 microns of the NW-SE oriented, central 80 × 200 pc of NGC 5236 (M83), with spectral resolution of 3200. We determine the kinematics of this region with 0.36 arcsec sampling, sub-arcsec resolution. Disk-like motions are detected in Paβ at parsec scales around: a) the optical nucleus (ON), b) the dynamical centre of the CO velocity map (Sakamoto et al 2004) coincident with the K–band center (hereafter KC; Thatte et al. 2000), located 50 pc to the W of the optical nucleus, and c) the hidden condensation (hereafter HN; Mast et al. 2006), now more precisely located at 120 pc to the N-NW of the optical nucleus. The disk around ON has a radius of 10–15 pc and those around KC and HN can be traced approximately up to 40-50 pc from their kinematical centres. Rotation curve fittings using Satoh like spheroids give masses of 2–4×106M⊙, 10–15×106M⊙ and 15–20×106M⊙ respectively. N-body simulations using Gadget2 (Springel, 2005) show that ON, KC and HN will merge in 20-50 Myrs. A question that arise immediately is if this degree of dynamical activity is peculiar of M83 or it is a common behaviour, seen in this galaxy in all its dramaticity due to its small distance from us.
The Jet-Cloud Interaction in 3CR Galaxies: Preliminary Results in Four Galaxies
Authors: Feinstein C. , Macchetto F. D. , Montero M. F. , Hägele G. F. 
Published: April 2007

AbstractWe present preliminary results of the Gemini/GMOS longslit spectra for four radiogalaxies: 3C 135, 3C 180, 3C 234 and 3C 284. These objects are a subsample of a set of galaxies with noticeable extended structure selected from the HST/WFPC2 3CR Snapshot Survey, data taken with the filters F555W, F702W and narrow-ramp. All of these objects show large regions of [Oiii]λ5007 emission (narrow ramp filter) and the broad-band filters data show similar structures indicating the presence of strong emission in several lines over these regions. The morphology observed seems to be related (e.g. same position angle, direct overlapping or similar shape) with the radio-jet. For some candidates with these properties GMOS/Gemini spectroscopy was taken. These data (both HST direct imaging and Gemini spectroscopy) can be tested with diagnostic diagrams and total UV photons budget to understand the source of energy that is ionizing the gas. This source of ionization was commonly believed to be the UV photons emitted by the powerful AGN, but several of these objects shows clearly that shocks produce by the radio jet are the main cause of the observed gas line emission.
A Case-Study of Grand-Design Warps in Galactic Disks
Authors: Józsa Gyula I. G. , Kenn F. , Klein U. , Oosterloo T. A. 
Published: April 2007

AbstractWe present the results of a case-study of three typical galaxies with integral-shaped warps. We apply a new method to directly fit tilted-ring models to high-quality Hi data cubes obtained with the WSRT and report on the features found to be present in the models.
Dynamical Evolution of the Mass Function of the Globular Cluster System from Fokker-Planck Calculations: Preliminary Results
Authors: Shin Jihye , Kim Sungsoo S. 
Published: April 2007

AbstractUsing anisotropic Fokker-Planck models, we calculate the evolution of mass and luminosity functions of the Galactic globular cluster system. Our models include two-body relaxation, binary heating, tidal shocks, dynamical friction, and stellar evolution. We perform Fokker-Planck simulations for a large number of virtual globular clusters and synthesize these results to study the relation between the initial and present GCMFs.
Narrow-Line Regions in Seyfert Galaxies and Quasars: Modelling 2D Kinematics
Authors: Jungwiert Bruno , Stoklasová Ivana , Bennert Nicola 
Published: April 2007

AbstractWe attempt to provide new insights into the kinematics of narrow-line regions (NLR) in Seyfert galaxies and quasars, the understanding of which, as well as of their intrinsic 3D morphology, is still rather limited. Motivated by the rise of the integral-field spectroscopy, capable of mapping full 2D velocity fields, and by our observational projects on NLRs (see e.g. Stoklasová et al., this volume) we have developed a computer code producing 2D kinematical maps resulting from projections of various gas geometries and velocity fields.
Asymmetric Warps in Disk Galaxies: Dependence on Dark Matter Halo
Authors: Saha K. , Jog C. J. 
Published: April 2007

AbstractRecent observations have shown that most of the warps in the disk galaxies are asymmetric. However there exists no generic mechanism to generate these asymmetries in warps. We have shown that a rich variety of possible asymmetries in the z-distribution of the spiral galaxies can naturally arise due to a dynamical wave interference between the first two bending modes i.e. bowl-shaped mode(m=0) and S-shaped warping mode(m = 1) in the galactic disk embedded in a dark matter halo. We show that the asymmetric warps are more pronounced when the dark matter content within the optical disk is lower as in early-type galaxies.