The Unimodal Distribution Of Blue Straggler Stars in M75 (NGC 6864)

We have used a combination of multiband high-resolution and wide-field ground-based observations to image the Galactic globular cluster M75 (NGC 6864). The extensive photometric sample covers the entire cluster extension, from the very central regions out to the tidal radius, allowing us to determine the center of gravity and to construct the most extended star density profile ever published for this cluster. We also present the first detailed star counts in the very inner regions. The star density profile is well re-produced by a standard King model with core radius r_c ~ 5.4" and intermediate-high concentration c ~ 1.75. The present paper presents a detailed study of the BSS population and its radial distribution. A total number of 62 bright BSSs (with m_F255W < 21, corresponding to m_F555W < 20) has been identified, and they have been found to be highly segregated in the cluster core. No significant upturn in the BSS frequency has been observed in the outskirts of M75, in contrast to several other clusters studied with the same technique. This observational fact is quite similar to what has been found in M79 (NGC 1904) by Lanzoni et al. (2007a). Indeed the BSS radial distributions in the two clusters is qualitatively very similar, even if in M75 the relative BSS frequency seems to decrease significantly faster than in M79: indeed it decreases by a factor of 5 (from 3.4 to 0.7) within 1 r_c. Such evidence indicate that the vast majority of the cluster heavy stars (binaries) have already sunk to the core.Comment: ApJ accepted, 10 pages, 11 figures, 2 table

Exotic populations in Globular Clusters: Blue Stragglers as tracers of the internal dynamical evolution of stellar systems

In this paper I present an overview of the main observational properties of a special class of exotic objects (the so-called Blue Straggler Stars, BSSs) in Galactic Globular Clusters (GCs). The BSS specific frequency and their radial distribution are discussed in the framework of using this stellar population as probe of GC internal dynamics. In particular, the shape of the BSS radial distribution has been found to be a powerful tracer of the dynamical evolution of stellar systems, thus allowing the definition of an empirical "clock" able to measure the dynamical age of stellar aggregates from pure observational properties.Comment: 10 pages, 6 figures. To be published in the Proceedings IAU Symposium No. 312, Star Clusters and Black Holes in Galaxies and Across Cosmic Tim

Pharmaceuticals entering Lake Champlain and their combination effects on developing Zebrafish Embryos

Human-derived pharmaceuticals have been identified entering surface waters in the United States through wastewater effluent. While there is ample literature about what each compound alone does to aquatic life, little is known about the effects aquatic life may experience from the exposure to many different pharmaceuticals present in the environment. More specifically, are the combination of pharmaceuticals in the environment more detrimental to aquatic life than each pharmaceutical alone? Zebrafish embryos were used to model what aquatic life in Lake Champlain may experience. Vatovec et al (2016) determined that there are 51 environmentally-relevant human derived pharmaceuticals entering Lake Champlain through wastewater effluent. Out of the 51, acetaminophen, carbamazepine, and diphenhydramine were studied. Embryos were exposed to each pharmaceutical for three days at various concentrations and observed for any developmental defects. The sub-lethal concentration of each pharmaceutical was determined and then this specific concentration was used in subsequent combination experiments. Results indicated that the exposure to all three pharmaceuticals were more detrimental to embryonic development than each pharmaceutical alone. However, when pharmaceuticals were combined in groups of two, one of the groups was more detrimental to embryos than the combination of all three pharmaceuticals. Although concentrations used in this experiment were much higher than that found in the environment, the implications of this study are still important. It is necessary to determine and demonstrate at what concentration pharmaceuticals are detrimental to aquatic life so that environmental concentrations never reach the concentrations used in the current experiment. The outcome of this research stands as a warning as to what may occur if nothing is done about pharmaceuticals entering water sources. Future studies should determine combination effects of pharmaceuticals at environmental concentrations

Phase space path integral in curved space

Phase space path integral is worked out in a riemannian geometry, by employing a prescription for the infinitesimal propagator that takes riemannian normal coordinates and momenta on an equal footing. The operator ordering induced by this prescription leads to the DeWitt curvature coupling in the Schrodinger equation.Comment: 11 page

Blue Straggler Stars: The Spectacular Population in M80

Using HST-WFPC2 observations in two ultraviolet (UV) filters (F225W and F336W) of the central region of the high density Galactic Globular cluster (GGC) M80 we have identified 305 Blue Straggler Stars (BSS) which represents the largest and most concentrated population of BSS ever observed in a GGC. We also identify the largest, clean sample of evolved BSS yet found. The high stellar density alone cannot explain the BSS, and we suggest that in M80 we are witnessing a transient dynamical state, during which stellar interactions are delaying the core-collapse process leading to an exceptionally large population of collisional-BSS.Comment: 15 pages, 5 figures, Astrophysical Journal Letters, in pres

Explaining gender differences in caries: a multifactorial approach to a multifactorial disease.

Many studies have demonstrated that caries rates are higher in women than in men. This review attempts to provide an explanation for this trend by examining each factor which contributes to caries and how the factor differs in men and women. Evidence has been provided to demonstrate that caries risk factors for women include a different salivary composition and flow rate, hormonal fluctuations, dietary habits, genetic variations, and particular social roles among their family. Systemic diseases that have been found to be associated with caries have also been found to have an association with the female gender. An extended exposure to the oral cavity or a more cariogenic oral microflora has not been proven to contribute to higher caries in women. Further research in these areas could be done in the future to explain their contribution, or lack thereof, to a higher caries rate in women

Explaining gender differences in caries: a multifactorial approach to a multifactorial disease.

Many studies have demonstrated that caries rates are higher in women than in men. This review attempts to provide an explanation for this trend by examining each factor which contributes to caries and how the factor differs in men and women. Evidence has been provided to demonstrate that caries risk factors for women include a different salivary composition and flow rate, hormonal fluctuations, dietary habits, genetic variations, and particular social roles among their family. Systemic diseases that have been found to be associated with caries have also been found to have an association with the female gender. An extended exposure to the oral cavity or a more cariogenic oral microflora has not been proven to contribute to higher caries in women. Further research in these areas could be done in the future to explain their contribution, or lack thereof, to a higher caries rate in women

The giant, horizontal and asymptotic branches of galactic globular clusters. I. The catalog, photometric observables and features

A catalog including a set of the most recent Color Magnitude Diagrams (CMDs) is presented for a sample of 61 Galactic Globular Clusters (GGCs). We used this data-base to perform an homogeneous systematic analysis of the evolved sequences (namely, Red Giant Branch (RGB), Horizontal Branch (HB) and Asymptotic Giant Branch (AGB)). Based on this analysis, we present: (1) a new procedure to measure the level of the ZAHB (V_ZAHB) and an homogeneous set of distance moduli obtained adopting the HB as standard candle; (2) an independent estimate for RGB metallicity indicators and new calibrations of these parameters in terms of both spectroscopic ([Fe/H]_CG97) and global metallicity ([M/H], including also the alpha-elements enhancement). The set of equations presented can be used to simultaneously derive a photometric estimate of the metal abundance and the reddening from the morphology and the location of the RGB in the (V,B-V)-CMD. (3) the location of the RGB-Bump (in 47 GGCs) and the AGB-Bump (in 9 GGCs). The dependence of these features on the metallicity is discussed. We find that by using the latest theoretical models and the new metallicity scales the earlier discrepancy between theory and observations (~0.4 mag) completely disappears.Comment: 51 pages, 23 figures, AAS Latex, macro rtrpp4.sty included, accepted by A

Explaining gender differences in caries: a multifactorial approach to a multifactorial disease.

Many studies have demonstrated that caries rates are higher in women than in men. This review attempts to provide an explanation for this trend by examining each factor which contributes to caries and how the factor differs in men and women. Evidence has been provided to demonstrate that caries risk factors for women include a different salivary composition and flow rate, hormonal fluctuations, dietary habits, genetic variations, and particular social roles among their family. Systemic diseases that have been found to be associated with caries have also been found to have an association with the female gender. An extended exposure to the oral cavity or a more cariogenic oral microflora has not been proven to contribute to higher caries in women. Further research in these areas could be done in the future to explain their contribution, or lack thereof, to a higher caries rate in women

Horizontal-Branch Models and the Second-Parameter Effect. IV. The Case of M3 and Palomar 3

We present a detailed analysis of the "second-parameter pair" of globular clusters M3 (NGC 5272) and Palomar 3. Our main results can be summarized as follows: i) The horizontal-branch (HB) morphology of M3 is significantly bluer in its inner regions (observed with the Hubble Space Telescope) than in the cluster outskirts (observed from the ground), i.e., M3 has an internal second parameter. Most plausibly the mass loss on the red giant branch (RGB) has been more efficient in the inner than in the outer regions of the cluster. ii) The dispersion in mass of the Pal 3 HB is found to be very small -- consistent with zero -- and we argue that this is unlikely to be due to a statistical fluctuation. It is this small mass dispersion that leads to the most apparent difference in the HB morphologies of M3 and Pal 3. iii) The relative HB types of M3 and Pal 3, as measured by mean colors or parameters involving the number of blue, variable, and red HB stars, can easily be accounted for by a fairly small difference in age between these clusters, of order 0.5-1 Gyr -- which is in good agreement with the relative age measurement, based on the clusters' turnoffs, by VandenBerg (2000).Comment: 20 pages, 12 figures, emulateapj5 style. The Astrophysical Journal, in press. Figs. 1, 6, 9, 10 are in png format. The preprint (postscript format) with full resolution (embedded) figures is available from http://www.astro.virginia.edu/~mc6v