Evaluation of the Sustainability of an Intervention to Increase HIV Testing

BACKGROUND Sustainability—the routinization and institutionalization of processes that improve the quality of healthcare—is difficult to achieve and not often studied. OBJECTIVE To evaluate the sustainability of increased rates of HIV testing after implementation of a multi-component intervention in two Veterans Health Administration healthcare systems. DESIGN Quasi-experimental implementation study in which the effect of transferring responsibility to conduct the provider education component of the intervention from research to operational staff was assessed. PATIENTS Persons receiving healthcare between 2005 and 2006 (intervention year) and 2006 and 2007 (sustainability year). MEASUREMENTS Monthly HIV testing rate, stratified by frequency of clinic visits RESULTS The monthly adjusted testing rate increased from 2% at baseline to 6% at the end intervention year and then declined reaching 4% at the end of the sustainability year. However, the stratified, visit-specific testing rate for persons newly exposed to the intervention (i.e., having their first through third visits during the study period) increased throughout the intervention and sustainability years. Increases in the proportion of visits by patients who remained untested despite multiple, prior exposures to the intervention accounted for the aggregate attenuation of testing during the sustainability year. Overall, the percentage of patients who received an HIV test in the sustainability year was 11.6%, in the intervention year 11.1%, and in the pre-intervention year 5.0% CONCLUSIONS Provider education combined with informatics and organizational support had a sustainable effect on HIV testing rates. The effect was most pronounced during patients' early contacts with the healthcare system.Health Services Research & Development Service (SDP 06–001

Lensing Effects on the Protogalaxy Candidate cB58 and their Implications for the Cosmological Constant

The amplification of the protogalaxy candidate cB58 due to gravitational lensing by the foreground cluster of galaxies MS1512.4+3647 is quantified based on recent ROSAT and ASCA X-ray observations. It is found that the amplification is at most 25 for any reasonable cosmological model with or without cosmological constant. It is also argued that the system may be used to place new constraints on the value of the cosmological constant. The gas mass fraction for this cluster is found to be about 0.2.Comment: LaTex, 9 pages, 9 figures, uses aas2pp4.sty, Accepted for publication in Ap

The Dearth of UV-Bright Stars in M32: Implications for Stellar Evolution Theory

Using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, we have obtained deep far-ultraviolet images of the compact elliptical galaxy M32. When combined with earlier near-ultraviolet images of the same field, these data enable the construction of an ultraviolet color-magnitude diagram of the hot horizontal branch (HB) population and other hot stars in late phases of stellar evolution. We find few post-asymptotic giant branch (PAGB) stars in the galaxy, implying that these stars either cross the HR diagram more rapidly than expected, and/or that they spend a significant fraction of their time enshrouded in circumstellar material. The predicted luminosity gap between the hot HB and its AGB-Manque (AGBM) progeny is less pronounced than expected, especially when compared to evolutionary tracks with enhanced helium abundances, implying that the presence of hot HB stars in this metal-rich population is not due to (Delta Y)/(Delta Z) > 4. Only a small fraction (~2%) of the HB population is hot enough to produce significant UV emission, yet most of the UV emission in this galaxy comes from the hot HB and AGBM stars, implying that PAGB stars are not a significant source of UV emission even in those elliptical galaxies with a weak UV excess.Comment: Accepted for publication in The Astrophysical Journal. Latex, 18 pages, 18 black & white figures, in emulate-ApJ format. Figures 11 & 16 have been degraded due to size constraints; the high-quality version of the paper is at http://www.stsci.edu/~tbrown/research/m32fuv.pd

Photometric Oscillations of Low Luminosity Red Giant Stars

I present details of the variations of several hundred red giant stars on time scales of a few hours to a few days from Hubble Space Telescope (HST) observations of a low-extinction galactic bulge sample from an intensive seven day campaign. Variations in the red giants are shown to be a strong function of position within the color-magnitude diagram (CMD) in accord with general expectations from theory. Amplitudes are greater for stars with larger radii, whether this results from higher luminosity at the same effective temperature or lower temperature at a fixed apparent magnitude. Likewise, characteristic time scales for the variations increase to the upper right in a CMD as does the ratio of amplitudes measured at 606 nm compared to 814 nm. Characteristic variation time scales are well matched by low-order radial pulsation modes. The effective sample discussed here extends from about two magnitudes above the bulge turnoff at which red giant radii are ~7 R/R_{\odot} at 5,000 K with typical amplitudes of ~0.5 mmag to ~40 R/R_{\odot} at 4,000 K with amplitudes of ~3.5 mmag. Variability characteristics are quite similar at any given position in the CMD, and at levels in the CMD where oscillations are easily detected nearly all red giants show such. If these variations represent oscillations with sufficient lifetimes to derive accurate mode frequencies more extensive observations, e.g. as should soon be provided by the Kepler Mission}, would provide a rich asteroseismic return.Comment: 36 pages, 12 figures, 7 tables; accepted for publication in A

Chemical behavior of the Dwarf Irregular Galaxy NGC 6822. Its PN and HII region abundances

We aim to derive the chemical behavior of a significant sample of PNe and HII regions in the irregular galaxy NGC 6822 The selected objects are distributed in different zones of the galaxy. Due to the faintness of PNe and HII regions in NGC 6822, to gather spectroscopic data with large telescopes is necessary. We obtained a well suited sample of spectra by employing VLT-FORS 2 and Gemini-GMOS spectrographs. Ionic and total abundances are calculated for the objects where electron temperatures can be determined through the detection of [OIII] \lambda 4363 or/and [NII] \lambda 5755 lines. A "simple" chemical evolution model has been developed and the observed data are used to compute a model for NGC 6822 in order to infer a preliminary chemical history in this galaxy. Confident determinations of He, O, N, Ne, S and Ar abundances were derived for a sample of 11 PNe and one HII region. We confirm that the present ISM is chemically homogeneous, at least in the central 2 kpc of the galaxy, showing a value 12+log O/H = 8.06$\pm$0.04. From the abundance pattern of PNe, we identified two populations: a group of young PNe with abundances similar to HII regions and a group of older objects with abundances a factor of two lower. A couple of extreme Type I PNe were found. No third dredge-up O enrichement was detected in PNe of this galaxy. The abundance determinations allow us to discuss the chemical behavior of the present and past ISM in NGC 6822. Our preliminary chemical evolution model predicts that an important gas-mass lost occurred during the first 5.3 Gyr, that no star higher than 40 M$_\odot$ was formed, and that 1% of all 3-15 M$_\odot$ stars became binary systems progenitors to SNIa.Comment: 15 pages, 3 figures and 4 tables. A&A, Accepted 13/06/200

Towards an understanding of tensile deformation in Ti-based bulk metallic glass matrix composites with BCC dendrites

The microstructure and tension ductility of a series of Ti-based bulk metallic glass matrix composite (BMGMC) is investigated by changing content of the β stabilizing element vanadium while holding the volume fraction of dendritic phase constant. The ability to change only one variable in these novel composites has previously been difficult, leading to uninvestigated areas regarding how composition affects properties. It is shown that the tension ductility can range from near zero percent to over ten percent simply by changing the amount of vanadium in the dendritic phase. This approach may prove useful for the future development of these alloys, which have largely been developed experimentally using trial and error

The Detailed Star Formation History in the Spheroid, Outer Disk, and Tidal Stream of the Andromeda Galaxy

Using the Advanced Camera for Surveys on the Hubble Space Telescope, we have obtained deep optical images reaching stars well below the oldest main sequence turnoff in the spheroid, tidal stream, and outer disk of the Andromeda Galaxy. We have reconstructed the star formation history in these fields by comparing their color-magnitude diagrams to a grid of isochrones calibrated to Galactic globular clusters observed in the same bands. Each field exhibits an extended star formation history, with many stars younger than 10 Gyr but few younger than 4 Gyr. Considered together, the star counts, kinematics, and population characteristics of the spheroid argue against some explanations for its intermediate-age, metal-rich population, such as a significant contribution from stars residing in the disk or a chance intersection with the stream's orbit. Instead, it is likely that this population is intrinsic to the inner spheroid, whose highly-disturbed structure is clearly distinct from the pressure-supported metal-poor halo that dominates farther from the galaxy's center. The stream and spheroid populations are similar, but not identical, with the stream's mean age being ~1 Gyr younger; this similarity suggests that the inner spheroid is largely polluted by material stripped from either the stream's progenitor or similar objects. The disk population is considerably younger and more metal-rich than the stream and spheroid populations, but not as young as the thin disk population of the solar neighborhood; instead, the outer disk of Andromeda is dominated by stars of age 4 - 8 Gyr, resembling the Milky Way's thick disk. The disk data are inconsistent with a population dominated by ages older than 10 Gyr, and in fact do not require any stars older than 10 Gyr.Comment: Accepted for publication in The Astrophysical Journal. 29 pages, 23 figures (including 9 in color), latex. Updated for minor edits and additional references. Images and CMDs are significantly smoothed and degraded in this version; a version with high-quality figures is available at http://www.stsci.edu/~tbrown/m31sfh/preprint.pd

Adaptive divergence in shoot gravitropism creates hybrid sterility in an Australian wildflower.

Natural selection is responsible for much of the diversity we see in nature. Just as it drives the evolution of new traits, it can also lead to new species. However, it is unclear whether natural selection conferring adaptation to local environments can drive speciation through the evolution of hybrid sterility between populations. Here, we show that adaptive divergence in shoot gravitropism, the ability of a plant's shoot to bend upwards in response to the downward pull of gravity, contributes to the evolution of hybrid sterility in an Australian wildflower, Senecio lautus We find that shoot gravitropism has evolved multiple times in association with plant height between adjacent populations inhabiting contrasting environments, suggesting that these traits have evolved by natural selection. We directly tested this prediction using a hybrid population subjected to eight rounds of recombination and three rounds of selection in the field. Our experiments revealed that shoot gravitropism responds to natural selection in the expected direction of the locally adapted population. Using the advanced hybrid population, we discovered that individuals with extreme differences in gravitropism had more sterile crosses than individuals with similar gravitropic responses, which were largely fertile, indicating that this adaptive trait is genetically correlated with hybrid sterility. Our results suggest that natural selection can drive the evolution of locally adaptive traits that also create hybrid sterility, thus revealing an evolutionary connection between local adaptation and the origin of new species

Discovery of An Unusually Blue L Dwarf Within 10 pc of the Sun

We report the discovery of an unusually blue L5 dwarf within 10 pc of the Sun from a search of Sloan Digital Sky Survey (SDSS) spectra. A spectrophotometric distance estimate of 8.0+/-1.6 pc places SDSS J141624.08+134826.7 among the six closest known L dwarfs. SDSS 1416+13 was overlooked in infrared color-based searches because of its unusually blue J-K_S color, which also identifies it as the nearest member of the blue L dwarf subclass. We present additional infrared and optical spectroscopy from the IRTF/SpeX and Magellan/MagE spectrographs and determine UVW motions that indicate thin disk kinematics. The inclusion of SDSS 1416+13 in the 20 pc sample of L dwarfs increases the number of L5 dwarfs by 20% suggesting that the L dwarf luminosity function may be far from complete.Comment: 15 pages, 3 figures, accepted for publication in AJ; updated version includes corrected radial velocit