FAST: A multi-processed environment for visualization of computational fluid

Three dimensional, unsteady, multizoned fluid dynamics simulations over full scale aircraft is typical of problems being computed at NASA-Ames on CRAY2 and CRAY-YMP supercomputers. With multiple processor workstations available in the 10 to 30 Mflop range, it is felt that these new developments in scientific computing warrant a new approach to the design and implementation of analysis tools. These large, more complex problems create a need for new visualization techniques not possible with the existing software or systems available as of this time. These visualization techniques will change as the supercomputing environment, and hence the scientific methods used, evolve ever further. Visualization of computational aerodynamics require flexible, extensible, and adaptable software tools for performing analysis tasks. FAST (Flow Analysis Software Toolkit), an implementation of a software system for fluid mechanics analysis that is based on this approach is discussed

The ACS Virgo Cluster Survey. VII. Resolving the Connection between Globular Clusters and Ultracompact Dwarf Galaxies

We investigate the connection between globular clusters and ultracompact dwarf galaxies (UCDs) by examining the properties of 10 compact, high-luminosity (-11.8 MV -10.8) objects associated with M87 (NGC 4486, VCC 1316), the cD galaxy in the Virgo Cluster. These objects, most of which were previously classified as M87 globular clusters, were selected from a combination of ground- and space-based imaging surveys. Our observational database for these objects—which we term DGTOs, or dwarf-globular transition objects —includes Advanced Camera for Surveys (ACS) F475W and F850LP imaging from the ACS Virgo Cluster Survey, integrated-light spectroscopy from Keck/ESI, and archival F606W WFPC2 imaging. We also present a search for DGTOs associated with other galaxies based on ACS imaging for 100 early-type galaxies in Virgo

The ACS Fornax Cluster Survey. II. The Central Brightness Profiles of Early-Type Galaxies: A Characteristic Radius on Nuclear Scales and the Transition from Central Luminosity Deficit to Excess

We analyse brightness profiles for 143 early-type galaxies in the Virgo and Fornax Clusters, observed with the Advanced Camera for Surveys on the Hubble Space Telescope. S´ersic models are found to provide accurate representations of the global profiles with a notable exception: the observed profiles deviate systematically inside a characteristic “break” radius of Rb ≈ 0.02+0.025 −0.01 Re, where Re is the effective radius of the galaxy. The sense of the deviation is such that bright galaxies (MB . −20) typically show central light deficits with respect to the inward extrapolation of the S´ersic model, while the great majority of low- and intermediate-luminosity galaxies (−19.5 . MB . −15) show central light excesses; galaxies of intermediate luminosities (−20 . MB . −19.5) are generally well fitted by S´ersic models over all radii. We show that the slope, ′, of the central surface brightness profiles, when measured at fixed fractions of Re, varies smoothly as a function of galaxy luminosity in a manner that depends sensitively on the choice of measurement radius. We find no evidence for a core/power-law dichotomy, and show that a recent claim of strong bimodality in ′ is likely an artifact of the biased galaxy selection function used in that study. To provide a more robust characterization of the inner regions of galaxies, we introduce a parameter, 0.02 = log (Lg/Ls) — where Lg and Ls are the integrated luminosities inside 0.02Re of the observed profile and of the inward extrapolation of the outer S´ersic model — to describe the central luminosity deficit ( 0.02 \u3c 0) or excess ( 0.02 \u3e 0). We find that 0.02 varies smoothly over the range of ≈ 720 in luminosity spanned by the sample galaxies, with again no evidence for a dichotomy. We argue that the central light excesses in MB & −19 galaxies may be the analogs of the dense central cores predicted by some numerical simulations to form via gas inflows

The ACS Virgo Cluster Survey. X. Half-Light Radii of Globular Clusters in Early-Type Galaxies: Environmental Dependencies and a Standard Ruler for Distance Estimation

We have measured half-light radii, rh, for thousands of globular clusters (GCs) belonging to the one hundred early-type galaxies observed in the ACS Virgo Cluster Survey and the elliptical galaxy NGC 4697. An analysis of the dependencies of the measured half-light radii on both the properties of the GCs themselves and their host galaxies reveals that, in analogy with GCs in the Galaxy but in a milder fashion, the average half-light radius increases with increasing galactocentric distance or, alternatively, with decreasing galaxy surface brightness. For the first time, we find that the average half-light radius decreases with the host galaxy color. We also show that there is no evidence for a variation of rh with the luminosity of the GCs. Finally, we find in agreement with previous observations that the average rh depends on the color of GCs, with red GCs being ∼ 17% smaller than their blue counterparts. We show that this difference is probably a consequence of an intrinsic mechanism, rather than projection effects, and that it is in good agreement with the mechanism proposed in Jord´an (2004). We discuss these findings in light of two simple pictures for the origin of the rh of GCs and show that both lead to a behavior in rough agreement with the observations. After accounting for the dependencies on galaxy color, galactocentric radius and underlying surface brightness, we show that the average GC half-light radii hrhi can be successfully used as a standard ruler for distance estimation. We outline the methodology, provide a calibration for its use, and discuss the prospects for this distance estimator with future observing facilities. We find hrhi = 2.7± 0.35 pc for GCs with (g − z) = 1.2 mag in a galaxy with color (g − z)gal = 1.5 mag and at an underlying surface z-band brightness of μz = 21 mag arcsec−2. Using this technique, we place an upper limit of 3.4 Mpc on the 1- line-of-sight depth of the Virgo Cluster. Finally, we examine the form of the rh distribution for our sample galaxies and provide an analytic expression which successfully describes this distribution

Trends in the Globular Cluster Luminosity Function of Early-Type Galaxies

We present results from a study of the globular cluster luminosity function (GCLF) in a sample of 89 earlytype galaxies observed as part of the ACS Virgo Cluster Survey. Using a Gaussian parametrization of the GCLF, we find a highly significant correlation between the GCLF dispersion, , and the galaxy luminosity, MB,gal, in the sense that the GC systems in fainter galaxies have narrower luminosity functions. The GCLF dispersions in the Milky Way and M31 are fully consistent with this trend, implying that the correlation between sigma and galaxy luminosity is more fundamental than older suggestions that GCLF shape is a function of galaxy Hubble type. We show that the -MB,gal relation results from a bonafide narrowing of the distribution of (logarithmic) cluster masses in fainter galaxies. We further show that this behavior is mirrored by a steepening of the GC mass function for relatively high masses,M& 3×105M⊙, a mass regime in which the shape of the GCLF is not strongly affected by dynamical evolution over a Hubble time. We argue that this trend arises from variations in initial conditions and requires explanation by theories of cluster formation. Finally, we confirm that in bright galaxies, the GCLF “turns over at the canonicalmass scale ofMTO ≃2×105M⊙. However, we find thatMTO scatters to lower values (≈ 1-2×105M⊙) in galaxies fainter than MB,gal & -18.5, an important consideration if the GCLF is to be used as a distance indicator for dwarf ellipticals

A Fundamental Relation between Compact Stellar Nuclei, Supermassive Black Holes, and Their Host Galaxies

Imaging surveys with the Hubble Space Telescope (HST) have shown that 50–80% of low- and intermediate-luminosity galaxies contain a compact stellar nucleus at their center, regardless of host galaxy morphological type. We combine HST imaging for early-type galaxies from the ACS Virgo Cluster Survey with ground-based long-slit spectra from KPNO to show that the masses of compact stellar nuclei in Virgo Cluster galaxies obey a tight correlation with the masses of the host galaxies. The same correlation is obeyed by the supermassive black holes (SBHs) found in predominantly massive galaxies. The compact stellar nuclei in the Local Group galaxies M33 and NGC 205 are also found to fall along this same scaling relation. These results indicate that a generic by-product of galaxy formation is the creation of a central massive object (CMO) — either a SBH or a compact stellar nucleus — that contains a mean fraction, 0.2%, of the total galactic mass. In galaxies with masses greater than Mgal a few 1010M⊙, SBHs appear to be the dominant mode of CMO formation

The Black Hole Mass of NGC 4151: Comparison of Reverberation Mapping and Stellar Dynamical Measurements

We present a stellar dynamical estimate of the black hole (BH) mass in the Seyfert 1 galaxy, NGC 4151. We analyze ground-based spectroscopy as well as imaging data from the ground and space, and we construct 3-integral axisymmetric models in order to constrain the BH mass and mass-to-light ratio. The dynamical models depend on the assumed inclination of the kinematic symmetry axis of the stellar bulge. In the case where the bulge is assumed to be viewed edge-on, the kinematical data give only an upper limit to the mass of the BH of ∼ 4 × 107 M⊙ (1 ). If the bulge kinematic axis is assumed to have the same inclination as the symmetry axis of the large-scale galaxy disk (i.e., 23◦ relative to the line of sight), a best-fit dynamical mass between 4 − 5 × 107 M⊙ is obtained. However, because of the poor quality of the fit when the bulge is assumed to be inclined (as determined by the noisiness of the 2 surface and its minimum value), and because we lack spectroscopic data that clearly resolves the BH sphere of influence, we consider our measurements to be tentative estimates of the dynamical BH mass. With this preliminary result, NGC 4151 is now among the small sample of galaxies in which the BH mass has been constrained from two independent techniques, and the mass values we find for both bulge inclinations are in reasonable agreement with the recent estimate from reverberation mapping (4.57+0.57 −0.47 × 107 M⊙) published by Bentz et al

The Hubble Space Telescope Advanced Camera for Surveys Coma Cluster Survey. I. Survey Objectives and Design

We describe the HST ACS Coma cluster Treasury survey, a deep twopassband imaging survey of one of the nearest rich clusters of galaxies, the Coma cluster (Abell 1656). The survey was designed to cover an area of 740 arcmin2 in regions of different density of both galaxies and intergalactic medium within the cluster. The ACS failure of January 27th 2007 leaves the survey 28% complete, with 21 ACS pointings (230 arcmin2) complete, and partial data for a further 4 pointings (44 arcmin2). Predicted survey depth for 10 detections for optimal photometry of point sources is g′ = 27.6 in the F475W filter, and IC=26.8 mag in F814 (AB magnitudes). Initial simulations with artificially injected point sources show 90% recovered at magnitude limits of g′ = 27.55 and IC = 26.65. For extended sources, the predicted 10 limits for a 1 arcsecond2 region are g′ = 25.8 mag arcsec−2 and IC = 25.0 mag arcsec−2. We highlight several motivating science goals of the survey, including study of the faint end of the cluster galaxy luminosity function, structural parameters of dwarf galaxies, stellar populations and their effect on colors and color gradients, evolution of morphological components in a dense environment, the nature of ultra compact dwarf galaxies, and globular cluster populations of cluster galaxies of a range of luminosities and types. This survey will also provide a local rich cluster benchmark for various well known global scaling relations and explore new relations pertaining to the nuclear properties of galaxies

Characterizing boreal peatland plant composition and species diversity with hyperspectral remote sensing

Peatlands, which account for approximately 15% of land surface across the arctic and boreal regions of the globe, are experiencing a range of ecological impacts as a result of climate change. Factors that include altered hydrology resulting from drought and permafrost thaw, rising temperatures, and elevated levels of atmospheric carbon dioxide have been shown to cause plant community compositional changes. Shifts in plant composition affect the productivity, species diversity, and carbon cycling of peatlands. We used hyperspectral remote sensing to characterize the response of boreal peatland plant composition and species diversity to warming, hydrologic change, and elevated CO2. Hyperspectral remote sensing techniques offer the ability to complete landscape-scale analyses of ecological responses to climate disturbance when paired with plot-level measurements that link ecosystem biophysical properties with spectral reflectance signatures. Working within two large ecosystem manipulation experiments, we examined climate controls on composition and diversity in two types of common boreal peatlands: a nutrient rich fen located at the Alaska Peatland Experiment (APEX) in central Alaska, and an ombrotrophic bog located in northern Minnesota at the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment. We found a strong effect of plant functional cover on spectral reflectance characteristics. We also found a positive relationship between species diversity and spectral variation at the APEX field site, which is consistent with other recently published findings. Based on the results of our field study, we performed a supervised land cover classification analysis on an aerial hyperspectral dataset to map peatland plant functional types (PFTs) across an area encompassing a range of different plant communities. Our results underscore recent advances in the application of remote sensing measurements to ecological research, particularly in far northern ecosystems

Manuka-type honeys can eradicate biofilms produced by Staphylococcus aureus strains with different biofilm-forming abilities

Chronic wounds are a major global health problem. Their management is difficult and costly, and the development of antibiotic resistance by both planktonic and biofilm-associated bacteria necessitates the use of alternative wound treatments. Honey is now being revisited as an alternative treatment due to its broad-spectrum antibacterial activity and the inability of bacteria to develop resistance to it. Many previous antibacterial studies have used honeys that are not well characterized, even in terms of quantifying the levels of the major antibacterial components present, making it difficult to build an evidence base for the efficacy of honey as an antibiofilm agent in chronic wound treatment. Here we show that a range of well-characterized New Zealand manuka-type honeys, in which two principle antibacterial components, methylglyoxal and hydrogen peroxide, were quantified, can eradicate biofilms of a range of Staphylococcus aureus strains that differ widely in their biofilm-forming abilities. Using crystal violet and viability assays, along with confocal laser scanning imaging, we demonstrate that in all S. aureus strains, including methicillin-resistant strains, the manuka-type honeys showed significantly higher anti-biofilm activity than clover honey and an isotonic sugar solution.We observed higher anti-biofilm activity as the proportion of manuka-derived honey, and thus methylglyoxal, in a honey blend increased. However, methylglyoxal on its own, or with sugar, was not able to effectively eradicate S. aureus biofilms.We also demonstrate that honey was able to penetrate through the biofilm matrix and kill the embedded cells in some cases. As has been reported for antibiotics, sub-inhibitory concentrations of honey improved biofilm formation by some S. aureus strains, however, biofilm cell suspensions recovered after honey treatment did not develop resistance towards manukatype honeys. New Zealand manuka-type honeys, at the concentrations they can be applied in wound dressings are highly active in both preventing S. aureus biofilm formation and in their eradication, and do not result in bacteria becoming resistant. Methylglyoxal requires other components in manuka-type honeys for this antibiofilm activity. Our findings support the use of well-defined manuka-type honeys as a topical anti-biofilm treatment for the effective management of wound healing. © 2014 Lu et al