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Search Results: 1 - 10 of 463753 matches for " G. S. Stinson "
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Challenges and Recommendations to Recruiting Women Who Do Not Adhere to Follow-Up Gynecological Care  [PDF]
LaShawn Wordlaw-Stinson, Sierra Jones, Shaneese Little, Laura Fish, Adriana Vidal, Cathrine Hoyo, Jennifer S. Smith, Patricia G. Moorman
Open Journal of Preventive Medicine (OJPM) , 2014, DOI: 10.4236/ojpm.2014.43017

Purpose: Non-adherence to recommended follow-up visits after an abnormal cytological finding is associated with poorer outcomes and higher health care costs. The purpose of this paper is to describe the challenges when examining reasons for non-adherence to cervical cancer screening follow-up and to discuss the recommendations to overcome those challenges. Methods: We conducted a telephone survey with two subgroups of women: 1) those which adhered to recommended follow-up care after an abnormal Pap test, and 2) those which did not adhere. Results: The follow-up accrual among non-adherent women lagged behind that of adherers. We were able to contact and conduct a survey with 51% of the adherers and 26% of the non-adherers. The challenges in studying non-adherent women were related to several distinct factors: 1) the definition of non-adherence, 2) the availability of alternate contact information, 3) the amount and type of financial incentives, and 4) the availability of staffing. We describe strategies employed to increase the accrual of non-adherent women. Discussion: This paper describes four recommendations that may play a role in understanding and reducing non-adherence to follow-up gynecological care.

High precision spectra at large redshift for dynamical DE cosmologies
S. A. Bonometto,L. Casarini,A. V. Maccio',G. Stinson
Physics , 2010, DOI: 10.1088/1742-6596/259/1/012025
Abstract: The next generation mass probes will investigate DE nature by measuring non-linear power spectra at various z, and comparing them with high precision simulations. Producing a complete set of them, taking into account baryon physics and for any DE state equation w(z), would really be numerically expensive. Regularities reducing such duty are essential. This paper presents further n-body tests of a relation we found, linking models with DE state parameter w(z) to const.-w models, and also tests the relation in hydro simulations.
Cosmological Galaxy Formation Simulations Using SPH
G. Stinson,J. Bailin,H. Couchman,J. Wadsley,S. Shen,C. Brook,T. Quinn
Physics , 2010, DOI: 10.1111/j.1365-2966.2010.17187.x
Abstract: We present the McMaster Unbiased Galaxy Simulations (MUGS), the first 9 galaxies of an unbiased selection ranging in total mass from 5$\times10^{11}$ M$_\odot$ to 2$\times10^{12}$ M$_\odot$ simulated using n-body smoothed particle hydrodynamics (SPH) at high resolution. The simulations include a treatment of low temperature metal cooling, UV background radiation, star formation, and physically motivated stellar feedback. Mock images of the simulations show that the simulations lie within the observed range of relations such as that between color and magnitude and that between brightness and circular velocity (Tully-Fisher). The greatest discrepancy between the simulated galaxies and observed galaxies is the high concentration of material at the center of the galaxies as represented by the centrally peaked rotation curves and the high bulge-to-total ratios of the simulations determined both kinematically and photometrically. This central concentration represents the excess of low angular momentum material that long has plagued morphological studies of simulated galaxies and suggests that higher resolutions and a more accurate description of feedback will be required to simulate more realistic galaxies. Even with the excess central mass concentrations, the simulations suggest the important role merger history and halo spin play in the formation of disks.
The Chemical and Dynamical Evolution of Isolated Dwarf Galaxies
K. Pilkington,B. K. Gibson,F. Calura,G. S. Stinson,C. B. Brook,A. Brooks
Physics , 2011, DOI: 10.1007/978-3-642-22018-0_4
Abstract: Using a suite of simulations (Governato et al. 2010) which successfully produce bulgeless (dwarf) disk galaxies, we provide an analysis of their associated cold interstellar media (ISM) and stellar chemical abundance patterns. A preliminary comparison with observations is undertaken, in order to assess whether the properties of the cold gas and chemistry of the stellar components are recovered successfully. To this end, we have extracted the radial and vertical gas density profiles, neutral hydrogen velocity dispersion, and the power spectrum of structure within the ISM. We complement this analysis of the cold gas with a brief examination of the simulations' metallicity distribution functions and the distribution of alpha-elements-to-iron.
Mechanisms of Baryon Loss for Dark Satellites in Cosmological SPH Simulations
S. Nickerson,G. Stinson,H. M. P. Couchman,J. Bailin,J. Wadsley
Physics , 2011, DOI: 10.1111/j.1365-2966.2011.18700.x
Abstract: We present a study of satellites in orbit around a high-resolution, smoothed particle hydrodynamics (SPH) galaxy simulated in a cosmological context. The simulated galaxy is approximately the same mass as the Milky Way. The cumulative number of luminous satellites at z = 0 is similar to the observed system of satellites orbiting the Milky Way although an analysis of the satellite mass function reveals an order of magnitude more dark satellites than luminous. Some of the dark subhalos are more massive than some of the luminous subhalos at z = 0. What separates luminous and dark subhalos is not their mass at z = 0, but the maximum mass the subhalos ever achieve. We study the effect of four mass loss mechanisms on the subhalos: ultraviolet (UV) ionising radiation, ram pressure stripping, tidal stripping, and stellar feedback, and compare the impact of each of these four mechanisms on the satellites. In the lowest mass subhalos, UV is responsible for the majority of the baryonic mass loss. Ram pressure stripping removes whatever mass remains from the low mass satellites. More massive subhalos have deeper potential wells and retain more mass during reionisation. However, as satellites pass near the centre of the main halo, tidal forces cause significant mass loss from satellites of all masses. Satellites that are tidally stripped from the outside can account for the luminous satellites that are lower mass than some of the dark satellites. Stellar feedback has the greatest impact on medium mass satellites that had formed stars, but lost all their gas by z = 0. Our results demonstrate that the missing satellite problem is not an intractable issue with the cold dark matter cosmology, but is rather a manifestation of baryonic processes.
The luminosity function of diverse satellite galaxy systems
S. Nickerson,G. Stinson,H. M. P. Couchman,J. Bailin,J. Wadsley
Physics , 2012, DOI: 10.1093/mnras/sts348
Abstract: The high-resolution, SPH galaxies of the McMaster Unbiased Galaxy Survey (MUGS) are used to examine the satellite systems of sixteen model host galaxies. Each galaxy has a different mass, angular momentum and merger history that yield a rich set of satellite luminosity functions. With new observations of distant satellite systems, we can compare these luminosity functions to satellite systems beyond the Local Group. We find that the luminosity functions of our simulations compare well to observations when the luminosity functions are scaled according to host mass. We use the recently-found relationship between dwarf satellites and host mass in distant satellite systems (Trentham & Tully 2009) to normalize a theoretical, complete luminosity function for the Milky Way (Koposov et al. 2008). The luminosity function of satellites, expressed as a function of the host mass, is given by dN/dM_V= 3.5 x M_host^(0.91) x 10^(0.1 x M_V-10.2), where host mass is given in M_sun. The mass of a host galaxy can be used to predict the number of dwarf satellites and even when considering spiral and elliptical hosts separately this relation holds.
Broadband Linear Polarization of Jupiter Trojans
S. Bagnulo,I. N. Belskaya,A. Stinson,A. Christou,G. B. Borisov
Physics , 2015,
Abstract: Trojan asteroids orbit in the Lagrange points of the system Sun-planet-asteroid. Their dynamical stability make their physical properties important proxies for the early evolution of our solar system. To study their origin, we want to characterize the surfaces of Jupiter Trojan asteroids and check possible similarities with objects of the main belt and of the Kuiper Belt. We have obtained high-accuracy broad-band linear polarization measurements of six Jupiter Trojans of the L4 population and tried to estimate the main features of their polarimetric behaviour. We have compared the polarimetric properties of our targets among themselves, and with those of other atmosphere-less bodies of our solar system. Our sample show approximately homogeneous polarimetric behaviour, although some distinct features are found between them. In general, the polarimetric properties of Trojan asteroids are similar to those of D- and P-type main-belt asteroids. No sign of coma activity is detected in any of the observed objects. An extended polarimetric survey may help to further investigate the origin and the surface evolution of Jupiter Trojans.
Constraining Sub-Grid Physics with High-Redshift Spatially-Resolved Metallicity Distributions
B. K. Gibson,K. Pilkington,C. B. Brook,G. S. Stinson,J. Bailin
Physics , 2013, DOI: 10.1051/0004-6361/201321239
Abstract: We examine the role of energy feedback in shaping the distribution of metals within cosmological hydrodynamical simulations of L* disc galaxies. While negative abundance gradients today provide a boundary condition for galaxy evolution models, in support of inside-out disc growth, empirical evidence as to whether abundance gradients steepen or flatten with time remains highly contradictory. We made use of a suite of L* discs, realised with and without `enhanced' feedback. All the simulations were produced using the smoothed particle hydrodynamics code Gasoline, and their in situ gas-phase metallicity gradients traced from redshift z~2 to the present-day. Present-day age-metallicity relations and metallicity distribution functions were derived for each system. The `enhanced' feedback models, which have been shown to be in agreement with a broad range of empirical scaling relations, distribute energy and re-cycled ISM material over large scales and predict the existence of relatively `flat' and temporally invariant abundance gradients. Enhanced feedback schemes reduce significantly the scatter in the local stellar age-metallicity relation and, especially, the [O/Fe]-[Fe/H] relation. The local [O/Fe] distribution functions for our L* discs show clear bimodality, with peaks at [O/Fe]=-0.05 and +0.05 (for stars with [Fe/H]>-1), consistent with our earlier work on dwarf discs. Our results with `enhanced' feedback are inconsistent with our earlier generation of simulations realised with `conservative' feedback. We conclude that spatially-resolved metallicity distributions, particularly at high-redshift, offer a unique and under-utilised constraint on the uncertain nature of stellar feedback processes.
The Evolution of Central Group Galaxies in Hydrodynamical Simulations
R. Feldmann,C. M. Carollo,L. Mayer,A. Renzini,G. Lake,T. Quinn,G. S. Stinson,G. Yepes
Physics , 2009, DOI: 10.1088/0004-637X/709/1/218
Abstract: We trace the evolution of central galaxies in three ~10^13 M_sun galaxy groups simulated at high resolution in cosmological hydrodynamical simulations. The evolution in the group potential leads, at z=0, to central galaxies that are massive, gas-poor early-type systems supported by stellar velocity dispersion resembling either elliptical or S0 galaxies. Their z~2-2.5 main progenitors are massive M* ~ 3-10 x 10^10 M_sun, star forming (20-60 M_sun/yr) galaxies which host substantial reservoirs of cold gas (~5 x 10^9 M_sun) in extended gas disks. Our simulations thus show that star forming galaxies observed at z~2 are likely the main progenitors of central galaxies in galaxy groups at z=0. Their central stellar densities stay approximately constant from z~1.5 down to z=0. Instead, the galaxies grow inside-out, by acquiring a stellar envelope outside the innermost ~2 kpc. Consequently the density within the effective radius decreases by up to two orders of magnitude. Both major and minor mergers contribute to most of the mass accreted outside the effective radius and thus drive the evolution of the half-mass radii. In one of the three simulated groups the short central cooling time leads to a dramatic rejuvenation of the central group galaxy at z<1, affecting its morphology, kinematics and colors. This episode is eventually terminated by a group-group merger. Our simulations demonstrate that, in galaxy groups, the interplay between halo mass assembly, galaxy merging and gas accretion has a substantial influence on the star formation histories and z=0 morphologies of central galaxies.[Abridged]
Polarimetry of transneptunian objects (136472) Makemake and (90482) Orcus
I. N. Belskaya,S. Bagnulo,A. Stinson,G. P. Tozzi,K. Muinonen,Yu. G. Shkuratov,M. A. Barucci,S. Fornasier
Physics , 2012, DOI: 10.1051/0004-6361/201220202
Abstract: Context. We study the surface properties of transneptunian populations of Solar-system bodies. Aims. We investigate the surface characteristics of the dwarf planet (136472) Makemake and the resonant object (90482) Orcus. Methods. Using the FORS2 instrument of the ESO-VLT we have carried out linear polarisation measurements of Makemake and Orcus. Results. Polarisation of Orcus is similar to that of smaller size objects. The polarimetric properties of Makemake are very close to those of Eris and Pluto. We have not found any significant differences in the polarisation properties of objects from different dynamical classes. However, there are significant differences in polarisation of large and smaller size objects, and between large TNOs with water-ice and methane-ice dominated surfaces. Conclusions. We confirm the different types of polarisation phase behavior for the largest and smaller size TNOs. To explain subtle surface polarisation of Pluto, Makemake and Eris we assume that their surfaces are covered by a thin layer of hoarfrost masking the surface structure.
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