Dwarf Galaxies in the Coma Cluster. I. Detection, Measurement and Classification Techniques

Deep B- and R-band CCD images of the central ~700 arcmin^2 of the Coma cluster core have been used to measure the dwarf-galaxy population in Coma. In this paper, we describe a newly developed code for automated detection, photometry and classification of faint objects of arbitrary shape and size on digital images. Intensity-weighted moments are used to compute the positions, radial structures, ellipticities, and integrated magnitudes of detected objects. We demonstrate that Kron-type 2r_1 aperture aperture magnitudes and surface brightnesses are well suited to faint-galaxy photometry of the type described here. Discrimination between starlike and extended (galaxy) objects is performed interactively through parameter-space culling in several possible parameters, including the radial moments, surface brightness, and integrated color versus magnitude. Our code is tested and characterized with artificial CCD images of star and galaxy fields; it is demonstrated to be accurate, robust and versatile. Using these analysis techniques, we detect a large population of dE galaxies in the Coma cluster core. These dEs stand out as a tight sequence in the R, (B-R) color-magnitude diagram.Comment: Accepted for publication PASP; 29 pages LaTeX (AASTeX using aaspp4.sty), with 9 EPS figures available from http://www.sci.wsu.edu/math/faculty/secker/ftp

The Early-type Dwarf-to-Giant Ratio and Substructure in the Coma Cluster

We have obtained new CCD photometry for a sample of $\simeq 800$ early-type galaxies (dwarf and giant ellipticals) in the central 700 arcmin$^2$ of the Coma cluster, complete in color and in magnitude to $R = 22.5$ mag ($M_R \simeq -12$ mag for $H_0 = 86$ km/sec/Mpc). The composite luminosity function for all galaxies in the cluster core (excluding NGC 4874 and NGC 4889) is modeled as the sum of a Gaussian distribution for the giant galaxies and a Schechter function for the dwarf elliptical galaxies. We determine that the early-type dwarf-to-giant ratio (EDGR) for Coma is identical to that measured for the less rich Virgo cluster; i.e., the EDGR does not increase as predicted by the EDGR-richness correlation. We postulate that the presence of substructure is an important factor in determining the cluster's EDGR; that is, the EDGR for Coma is consistent with the Coma cluster being built up from the merger of multiple less-rich galaxy clusters.Comment: 13 pages, LaTeX file, 3 EPS figures, uses aaspp4.sty; also available from: http://www.sci.wsu.edu/math/faculty/secker/secker.html; to be published in ApJ, 469 (Oct.1, 1996

The Impact of Religious Commitment on Women’s Sexual Self-Esteem

Religious commitment is associated with decreased sexual activity, poor sexual satisfaction, and sexual guilt, particularly among women. The purpose of this paper was to investigate how religious commitment is related to sexual self-esteem among women. Participants included 196 female undergraduate students, 87 % of whom identified as Christian. Participants completed the Sexual Self-Esteem Inventory for Women (SSEI-W), Religious Commitment Inventory-10, Revised Religious Fundamentalism Scale, Brief Sexual Attitudes Scale, and a measure of their perception of God’s view of sex. Results suggested that women with high religious commitment held more conservative sexual attitudes. Significant relationships between religious commitment and two subscales (moral judgment and attractiveness) of the SSEI-W revealed that women with high religious commitment were less likely to perceive sex as congruent with their moral values and simultaneously reported significantly greater confidence in their sexual attractiveness. A significant relationship between religious commitment and overall sexual self-esteem was found for women whose religion of origin was Catholicism, such that those with higher religious commitment reported lower sexual self-esteem. A hierarchical regression analysis revealed that high religious commitment and perception that God viewed sex negatively independently predicted lower sexual selfesteem, as related to moral judgment. Implications of the findings are provided

Dwarf Galaxies in the Coma Cluster. II. Photometry and Analysis

We study the dwarf galaxy population in the central ~700 arcmin^2 of the Coma cluster, the majority of which are early-type dwarf elliptical (dE) galaxies. Analysis of the statistically-decontaminated dE galaxy sequence in the color-magnitude diagram reveals a highly significant trend of color with magnitude (\Delta (B-R)/\Delta R = -0.056\pm0.002 mag), in the sense that fainter dEs are bluer and thus presumably more metal-poor. The mean color of the faintest dEs in our sample is (B-R)~1.15 mag, consistent with a color measurement of the diffuse intracluster light in the Coma core. This intracluster light could then have originated from the tidal disruption of faint dEs in the cluster core. The total galaxy luminosity function (LF) is well modeled as the sum of a log-normal distribution for the giant galaxies, and a Schechter function for the dE galaxies with a faint-end slope \alpha = -1.41\pm0.05. This value of \alpha is consistent with those measured for the Virgo and Fornax clusters. The spatial distribution of the faint dE galaxies (19.0 < R \le 22.5 mag) has R_c = 22.15 arcmin (~0.46h^{-1} Mpc), significantly larger than the R_c = 13.71 arcmin (~0.29h^{-1} Mpc) found for the cluster giants and the brighter dEs (R \le 19.0 mag), consistent with tidal disruption of the faint dEs. Finally, we find that most dEs belong to the general Coma cluster potential rather than as satellites of individual giant galaxies: An analysis of the number counts around 10 cluster giants reveals that they each have on average 4\pm 1 dE companions within a projected radius of 13.9h^{-1} kpc. (Abridged)Comment: Accepted for publication in PASP; 36 pages LaTeX (AASTex using aaspp4.sty), with 14 EPS figures available from http://www.sci.wsu.edu/math/faculty/secker/ftp/ ; Single change in the Introduction (50 kpc corrected to read 50 pc

Coupled Fluid-Structure Interaction Analysis of Solid Rocket Motor with Flexible Inhibitors

Flexible inhibitors are generally used in solid rocket motors (SRMs) as a means to control the burning of propellant. Vortices generated by the flow of propellant around the flexible inhibitors have been identified as a driving source of instabilities that can lead to thrust oscillations in launch vehicles. Potential coupling between the SRM thrust oscillations and structural vibration modes is an important risk factor in launch vehicle design. As a means to predict and better understand these phenomena, a multidisciplinary simulation capability that couples the NASA production CFD code, Loci/CHEM, with CFDRC's structural finite element code, CoBi, has been developed. This capability is crucial to the development of NASA's new space launch system (SLS). This paper summarizes the efforts in applying the coupled software to demonstrate and investigate fluid-structure interaction (FSI) phenomena between pressure waves and flexible inhibitors inside reusable solid rocket motors (RSRMs). The features of the fluid and structural solvers are described in detail, and the coupling methodology and interfacial continuity requirements are then presented in a general Eulerian-Lagrangian framework. The simulations presented herein utilize production level CFD with hybrid RANS/LES turbulence modeling and grid resolution in excess of 80 million cells. The fluid domain in the SRM is discretized using a general mixed polyhedral unstructured mesh, while full 3D shell elements are utilized in the structural domain for the flexible inhibitors. Verifications against analytical solutions for a structural model under a steady uniform pressure condition and under dynamic modal analysis show excellent agreement in terms of displacement distribution and eigenmode frequencies. The preliminary coupled results indicate that due to acoustic coupling, the dynamics of one of the more flexible inhibitors shift from its first modal frequency to the first acoustic frequency of the solid rocket motor. This insight could have profound implications for SRM and flexible inhibitor designs for current and future launch vehicles including SLS

One VCU Art

Art and creativity are at the core of VCU’s identity and culture. ONE VCU Art envisions a vibrant and diverse public art landscape on the VCU campuses that equals VCU’s national reputation and enhances connections with our urban home of Richmond. VCU’s nationally ranked arts programs as well as its relationship with the city of Richmond allow for opportunity to revive efforts to enhance current and future public art on the two Richmond campuses. This is in conjunction with the goals and priorities set out by the VCU strategic plan, Quest 2025: Together We Transform

Promoting VCU Community Solutions

This promotional project focuses on VCU Community Solutions — the new interdisciplinary initiative for education, research, and service. Since this initiative demonstrates the synergy that students, faculty, and community members can create by working together, the promotional video captures their perspectives. Through interviews and footage of community programs, the video shows how VCU Community Solutions engages university and community partners in addressing critical social issues — creating more imovative approaches by working together

Influence of Acute Turkesterone Dosing on Serum Insulin-like Growth Factor 1 (IGF-1) and Subjective Digestibility Scores in Recreationally-active Males

Turkesterone is a relatively novel phytoecdysteroid compound that has become increasingly popular amongst recreationally active demographics. Despite prior in vitro data suggesting that this compound may support enhanced body composition via both insulin-like growth factor 1 (IGF-1)-mediated protein synthesis, no human evidence exists in this regard nor how well its digestibility is tolerated. PURPOSE: To determine the effect of multiple turkesterone doses on serum IGF-1 and to report any gastrointestinal (GI) distress symptoms in a healthy human sample. METHODS: Eleven recreationally active males (23.3±2.2y) visited the laboratory on three occasions separated by at least seven days and were randomized in single-blind, placebo-controlled, and counter-balanced crossover fashion to either 2000mg cellulose placebo (PLA), 1000mg turkesterone + 1000mg placebo, (1000T) or 2000mg (2000T) turkesterone. Venous blood was sampled to determine serum IGF-1 concentrations and a GI distress questionnaire was (nausea, vomiting, heartburn symptoms, etc.) administered both at baseline (PRE), as well as 3-hours (POST3H) and 24-hours (POST24H) post-acute supplementation at each visit. Serum IGF-1 was analyzed using a two-way (condition [PLA, 1000T, 2000T] x time [PRE, POST3H, POST24H]) ANOVA with repeated measures at a significance level of pRESULTS: Analyses failed to reveal any significant condition (p=.180; ηp2=0.228), time (p=0.227; ηp2=.390), nor interaction effects (p=0.547; ηp2=0.211) for serum IGF-1. Moreover, no participants reported any GI distress symptoms across any condition and/or time permutation. CONCLUSION: Although the current study did not find any significant IGF-1-associated serum alterations to multiple acute turkesterone doses in the times assessed, there were fortunately no adverse GI symptoms experienced by the participants across any dose throughout the investigation. Nevertheless, these data support turkesterone supplementation is well tolerated and thus future research should build upon our analysis by employing a longitudinal supplementation regimen alongside an exercise intervention to elucidate the potential long-term and anabolism-permissive impacts of this compound on the presently-explored and additional associated parameters

The WFC3 Galactic Bulge Treasury Program: A First Look at Resolved Stellar Population Tools

[Abridged] When WFC3 is installed on HST, the community will have powerful new tools for investigating resolved stellar populations. The WFC3 Galactic Bulge Treasury program will obtain deep imaging on 4 low-extinction fields. These non-proprietary data will enable a variety of science investigations not possible with previous data sets. To aid in planning for the use of these data and for future proposals, we provide an introduction to the program, its photometric system, and the associated calibration effort. The observing strategy is based upon a new 5-band photometric system spanning the UV, optical, and near-infrared. With these broad bands, one can construct reddening-free indices of Teff and [Fe/H]. Besides the 4 bulge fields, the program will target 6 fields in well-studied star clusters, spanning a wide range of [Fe/H]. The cluster data serve to calibrate the indices, provide population templates, and correct the transformation of isochrones into the WFC3 photometric system. The bulge data will shed light on the bulge formation history, and will also serve as population templates for other studies. One of the fields includes 12 candidate hosts of extrasolar planets. CMDs are the most popular tool for analyzing resolved stellar populations. However, due to degeneracies among Teff, [Fe/H], and reddening in traditional CMDs, it can be difficult to draw robust conclusions from the data. The 5-band system used for the bulge Treasury observations will provide indices that are roughly orthogonal in Teff and [Fe/H], and we argue that model fitting in an index-index diagram will make better use of the information than fitting separate CMDs. We provide simulations to show the expected data quality and the potential for differentiating between different star-formation histories.Comment: Accepted for publication in The Astronomical Journal. 9 pages, 8 figures, latex, AJ forma

The Hubble Constant from Observations of the Brightest Red Giant Stars in a Virgo-Cluster Galaxy

The Virgo and Fornax clusters of galaxies play central roles in determining the Hubble constant H_0. A powerful and direct way of establishing distances for elliptical galaxies is to use the luminosities of the brightest red-giant stars (the TRGB luminosity, at M_I = -4.2). Here we report the direct observation of the TRGB stars in a dwarf elliptical galaxy in the Virgo cluster. We find its distance to be 15.7 +- 1.5 Megaparsecs, from which we estimate a Hubble constant of H_0 = 77 +- 8 km/s/Mpc. Under the assumption of a low-density Universe with the simplest cosmology, the age of the Universe is no more than 12-13 billion years.Comment: 12 pages, LaTeX, with 2 postscript figures; in press for Nature, July 199