Encouraging Excellence: commemorating the 75th Anniversary of the School of Dentistry

This book celebrates the 75th anniversary of the School of Dentistry at the Medical College of Virginia (MCV). In 1897, the School of Dentistry was founded at MCV. Through biographies, images, and brief histories, this book details major benchmarks of the school’s history. This document also includes a brief description of the dentistry profession and images of antique dentistry equipment. The document concludes with biographies of the deans of the School of Dentistry.https://scholarscompass.vcu.edu/vcu_books/1010/thumbnail.jp

Quantifying the Coexistence of Massive Black Holes and Dense Nuclear Star Clusters

In large spheroidal stellar systems, such as elliptical galaxies, one invariably finds a 10^6-10^9 M_Sun supermassive black hole at their centre. In contrast, within dwarf elliptical galaxies one predominantly observes a 10^5-10^7 M_Sun nuclear star cluster. To date, few galaxies have been found with both type of nuclei coexisting and even less have had the masses determined for both central components. Here we identify one dozen galaxies housing nuclear star clusters and supermassive black holes whose masses have been measured. This doubles the known number of such hermaphrodite nuclei - which are expected to be fruitful sources of gravitational radiation. Over the host spheroid (stellar) mass range from 10^8 to 10^11 M_Sun, we find that a galaxy's nucleus-to-spheroid (baryon) mass ratio is not a constant value but decreases from a few percent to ~0.3 percent such that log[(M_BH+M_NC)/M_sph] = -(0.39+/-0.07)log[M_sph/10^10 M_Sun] -(2.18+/-0.07). Once dry merging has commenced by M_sph ~ 10^11 M_Sun and the nuclear star clusters have disappeared, this ratio is expected to become a constant value. As a byproduct of our investigation, we have found that the projected flux from resolved nuclear star clusters can be well approximated with Sersic functions having a range of indices from ~0.5 to ~3, the latter index describing the Milky Way's nuclear star cluster.Comment: To appear in MNRA

A New Method for Estimating Dark Matter Halo Masses using Globular Cluster Systems

All galaxies are thought to reside within large halos of dark matter, whose properties can only be determined from indirect observations. The formation and assembly of galaxies is determined from the interplay between these dark matter halos and the baryonic matter they host. Although statistical relations can be used to approximate how massive a galaxy's halo is, very few individual galaxies have direct measurements of their halo masses. We present a method to directly estimate the total mass of a galaxy's dark halo using its system of globular clusters. The link between globular cluster systems and halo masses is independent of a galaxy's type and environment, in contrast to the relationship between galaxy halo and stellar masses. This trend is expected in models where globular clusters form in early, rare density peaks in the cold dark matter density field and the epoch of reionisation was roughly coeval throughout the Universe. We illustrate the general utility of this relation by demonstrating that a galaxy's supermassive black hole mass and global X-ray luminosity are directly proportional to their host dark halo masses, as inferred from our new method.Comment: 6 pages, 4 colour figures. Accepted by MNRAS Letters. Data catalogue available from the first autho

Extending the baseline: Spitzer Mid-Infrared Photometry of Globular Cluster Systems in the Centaurus A and Sombrero Galaxies

Spitzer IRAC mid-infrared photometry is presented for the globular cluster (GC) systems of the NGC 5128 ("Centaurus A") and NGC 4594 ("Sombrero") galaxies. Existing optical photometric and spectroscopic are combined with this new data in a comprehensive optical to mid-IR colour catalogue of 260 GCs. Empirical colour-metallicity relationships are derived for all optical to mid-IR colour combinations. These colours prove to be very effective quantities to test the photometric predictions of simple stellar population (SSP) models. In general, four SSP models show larger discrepancies between each other and the data at bluer wavelengths, especially at high metallicities. Such differences become very important when attempting to use colour-colour model predictions to constrain the ages of stellar populations. Furthermore, the age-substructure determined from colour-colour diagrams and 91 NGC 5128 GCs with spectroscopic ages from Beasley et al. (2008) are inconsistent, suggesting any apparent GC system age-substructure implied by a colour-colour analysis must be verified independently. Unlike blue wavebands, certain optical to mid-IR colours are insensitive to the flux from hot horizontal branch stars and thus provide an excellent metallicity proxy. The NGC 5128 GC system shows strong bimodality in the optical R-band to mid-IR colour distributions, hence proving it is bimodal in metallicity. In this new colour space, a colour-magnitude trend, a "blue tilt", is found in the NGC 5128 metal-poor GC data. The NGC 5128 young GCs do not contribute to this trend. [abridged]Comment: 16 pages, 12 colour figures. To be published in MNRAS. Catalogue available from the first author. Full resolution copy available here http://lee.spitler.googlepages.com/spitzer_spitler.pd

Development of a Detailed Heat Pump Simulation Controls Testbed

In order to increase energy efficiency, it is desirable to reduce power consumption of HVAC systems. One way to reduce power consumption is through careful control of system components. To this end, this work covers the theoretical development of a detailed heat pump testbed for controls. The testbed was created by coupling a whole building simulation model, a detailed heat pump simulation model, an optimization engine, and two data exchange managers. Three component variables were investigated to reduce power: compressor refrigerant flow rate, condenser fan air flow rate, and evaporator air fan flow rate. It was seen that the most impactful variable on capacity and power was the compressor ratio, with the evaporator air fan flow rate having the second greatest impact, and the condenser air fan flow rate the least impact. In addition, an optimizing control that minimizes energy consumption and uses a penalty function to maintain space temperature was added to the testbed. Finally, a number of incremental test cases provide proof of concept for this testbed

Using Information Technology in Knowledge Work

The purpose of the present research is to develop a theoretical framework which explores how knowledge workers learn their jobs and the role that using IT plays therein. The present research, based on theoretical underpinnings derived from the theory of legitimate peripheral participation (Lave and Wenger 1991), is an interpretive case study and is founded on the assumptions that problem-solving and learning are situated in practice, context-specific, and socially constructed. To develop further the theoretical framework, the author has gained access to a global strategic management consulting firm with offices in New York City where she is using ethnographic methods of interviewing and participant observation. The research is expected to have implications for training, mentoring and incentive policies for organizations operating in the IT-based, knowledge economy

Absolute profinite rigidity and hyperbolic geometry

We construct arithmetic Kleinian groups that are profinitely rigid in the absolute sense: each is distinguished from all other finitely generated, residually finite groups by its set of finite quotients. The Bianchi group $\mathrm{PSL}(2,\mathbb{Z}[\omega])$ with $\omega^2+\omega+1=0$ is rigid in this sense. Other examples include the non-uniform lattice of minimal co-volume in $\mathrm{PSL}(2,\mathbb{C})$ and the fundamental group of the Weeks manifold (the closed hyperbolic $3$-manifold of minimal volume).Comment: v2: 35 pages. Final version. To appear in the Annals of Mathematics, Vol. 192, no. 3, November 202

Binding of Independent Contexts in Source Memory

Within the present study the binding between two independent source dimensions in a multidimensional source memory paradigm was investigated. Specifically, I examined stochastic dependence between the retrieval of each source dimension. Previous work has defined stochastic dependence as the higher probability of correct source retrieval for one dimension contingent on previous correct retrieval of a second source dimension, versus when contingent on incorrect retrieval of the second source dimension. Evidence is mixed as to whether item information within source dimensions must be encoded simultaneously in order to demonstrate eventual stochastic dependence. The present study tested the binding of two cross-modal source attributes (visual [left or right side of screen] and auditory [male or female voice]) over time by manipulating the lag between each independently-encoded source dimension. Source dimensions were encoded simultaneously or separately by two intervening encoding trials (separate condition). Based on the behavioral measures of binding, source dimensions presented more closely in time resulted in stochastic dependence in the context of remembering and not knowing. However, a multinomial model of response frequencies produced evidence of joint retrieval in the context of remembering for both the simultaneous and separate conditions. Because source dimensions were presented over time in some conditions, working memory capacity was measured as a potential predictor of stochastic dependence. However, working memory measures did not correlate with source memory performance. Future directions in examining this separate condition, stochastic dependence and individual differences in working memory capacity are discussed

Hemolysis in runners as evidenced by low serum haptoglobin: Implications for preflight monitoring of astronauts

Hematological parameters and serum haptoglobin were examined in 21 male employees of the Kennedy Space Center who were at 3 levels of physical activity: 7 subjects regularly ran more than 40 km (25 miles) per week (Group I); 7 ran 13 to 24 km (8 to 15 miles) per week (II), and 7 were sedentary (III). Blood was drawn on a different day of the week for five weeks. Differences between day of the week, visit number, and activity level were examined. No differences were observed for day of week or visit number; thus mean values for each variable were calculated for each subject. Variables did not differ among groups. However, trends with level of training were observed in some critical variables. Hemoglobin (Hb) and hematocrit (Hct) conformed to a staircase effect with Group I (14.5 gm/dl and 41.3 percent) lower than Group III (15.1 gm/dl and 42.9 percent). Reticulocyte count was higher and haptoglobin levels lower in Group I (1.35% and 75.7 gm/dl) than Group III (.99 percent and 132.9 gm/dl), with haptoglobin for the high mileage Group I in the clinically abnormal range. Since haptoglobin binds free Hb following RBC destruction, these results suggest that intravascular hemolysis occurs in trained male runners. These results may have special meaning for astronauts training before long-duration spaceflights, since the further reduction in red blood cells which is reported to occur during spaceflight could become detrimental to their health and performance