Probing the IGM/Galaxy Connection IV: The LCO/WFCCD Galaxy Survey of 20 Fields Surrounding UV Bright Quasars

We publish the survey for galaxies in 20 fields containing ultraviolet bright quasars (with z_em 0.1 to 0.5) that can be used to study the association between galaxies and absorption systems from the low-z intergalactic medium (IGM). The survey is magnitude limited (R~19.5 mag) and highly complete out to 10' from the quasar in each field. It was designed to detect dwarf galaxies (L ~ 0.1 L*) at an impact parameter rho 1Mpc (z=0.1) from a quasar. The complete sample (all 20 fields) includes R-band photometry for 84718 sources and confirmed redshifts for 2800 sources. This includes 1198 galaxies with 0.005 < z < (z_em - 0.01) at a median redshift of 0.18, which may associated with IGM absorption lines. All of the imaging was acquired with cameras on the Swope 40" telescope and the spectra were obtained via slitmask observations using the WFCCD spectrograph on the Dupont 100" telescope at Las Campanas Observatory (LCO). This paper describes the data reduction, imaging analysis, photometry, and spectral analysis of the survey. We tabulate the principal measurements for all sources in each field and provide the spectroscopic dataset online.Comment: Accepted to the Astrophysical Journal Supplements; 20 pages, only 6 figures shown in this version. See http://www.ucolick.org/~xavier/WFCCDOVI/index.html for a full-length manuscript and other supportive materia

The information needs of people living with ankylosing spondylitis: a questionnaire survey

&lt;p&gt;BACKGROUND:Today, health care is patient-centred with patients more involved in medical decision making and taking an active role in managing their disease. It is important that patients are appropriately informed about their condition and that their health care needs are met. We examine the information utilisation, sources and needs of people with ankylosing spondylitis (AS).&lt;/p&gt; &lt;p&gt;METHODS: Participants in an existing AS cohort study were asked to complete a postal or online questionnaire containing closed and open-ended questions, regarding their information access and needs. Participants were stratified by age and descriptive statistics were performed using STATA 11, while thematic analysis was performed on open-ended question narratives. Qualitative data was handled in Microsoft Access and explored for emerging themes and patterns of experiences.&lt;/p&gt; &lt;p&gt;RESULTS: Despite 73% of respondents having internet access, only 49% used the internet to access information regarding AS. Even then, this was only infrequently. Only 50% of respondents reported accessing written information about AS, which was obtained mainly in specialist clinics. Women were more likely than men to access information (63% (women) 46% (men)) regardless of the source, while younger patients were more likely to use online sources. The main source of non-written information was the rheumatologist. Overall, the respondents felt there was sufficient information available, but there was a perception that the tone was often too negative. The majority (95%) of people would like to receive a regular newsletter about AS, containing positive practical and local information. Suggestions were also made for more information about AS to be made available to non-specialist medical professionals and the general public.&lt;/p&gt; &lt;p&gt;CONCLUSIONS: There appears to be sufficient information available for people with AS in the UK and this is mostly accessed by younger AS patients. Many patients, particularly men, choose not to access AS information and concerns were raised about its negative tone. Patients still rely on written and verbal information from their specialists. Future initiatives should focus on the delivery of more positive information, targeting younger participants in particular and increasing the awareness in the general population and wider non-specialist medical community.&lt;/p&gt

Characterization of toxic impacts on living marine resources in tidal rivers of the Chesapeake Bay

In 1999, the Chesapeake Bay Program completed a survey of existing data on chemical contaminants and the potential for bioeffects in 38 tidal river systems of Chesapeake Bay. This review led to the identification of 20 areas for which there were insufficient data to adequately characterize the potential for contaminant bioeffects on the Bay’s living resources. The goal of the present study was to estimate the current status of ecological condition in five of these areas and thus help to complete the overall toxics inventory for the Bay. These five systems included the Chester River, Nanticoke River, Pocomoke River, Lower Mobjack Bay (Poquosin and Back Rivers) and the South and Rhode Rivers. This study utilized a Sediment Quality Triad (SQT) approach in combination with additional water-column contaminant analysis to allow for a “weight of evidence” assessment of environmental condition. A total of 60 stations distributed among the five systems, using a probabilistic stratified random design, were sampled during the summer of 2004 to allow for synoptic measures of sediment contamination, sediment toxicity, and benthic condition. Upon completion of all analyses, stations were assigned to one of four categories based on the three legs of the triad. Stations with high sediment quality had no hits on any of the three legs of the triad; those with moderate quality had one hit; those with marginal quality had two hits; and those with poor quality had hits for all three legs of the triad. The Pocomoke River had by far the largest proportion of the total area (97.5%) classified as having high sediment quality, while the Rhode/South system had the highest proportion (11.4%) classified as poor. None of the stations in the Chester River, Nanticoke River, and Lower Mobjack Bay systems were classified as poor. More than 65% of the area of each of the five systems was classified with high to moderate sediment quality. The Rhode/South system had 30.4% of total area classified with marginally to severely poor quality. The results of this study highlight the importance of using multiple indicators and a “weight of evidence” approach to characterize environmental quality and the potential bioeffects of toxic contaminants

On the Kinematics of Cold, Metal-enriched Galactic Fountain Flows in Nearby Star-forming Galaxies

We use medium-resolution Keck/Echellette Spectrograph and Imager spectroscopy of bright quasars to study cool gas traced by CaII 3934,3969 and NaI 5891,5897 absorption in the interstellar/circumgalactic media of 21 foreground star-forming galaxies at redshifts 0.03 < z < 0.20 with stellar masses 7.4 < log M_*/M_sun < 10.6. The quasar-galaxy pairs were drawn from a unique sample of Sloan Digital Sky Survey quasar spectra with intervening nebular emission, and thus have exceptionally close impact parameters (R_perp < 13 kpc). The strength of this line emission implies that the galaxies' star formation rates (SFRs) span a broad range, with several lying well above the star-forming sequence. We use Voigt profile modeling to derive column densities and component velocities for each absorber, finding that column densities N(CaII) > 10^12.5 cm^-2 (N(NaI) > 10^12.0 cm^-2) occur with an incidence f_C(CaII) = 0.63^+0.10_-0.11 (f_C(NaI) = 0.57^+0.10_-0.11). We find no evidence for a dependence of f_C or the rest-frame equivalent widths W_r(CaII K) or W_r(NaI 5891) on R_perp or M_*. Instead, W_r(CaII K) is correlated with local SFR at >3sigma significance, suggesting that CaII traces star formation-driven outflows. While most of the absorbers have velocities within +/-50 km/s of the host redshift, their velocity widths (characterized by Delta v_90) are universally 30-177 km/s larger than that implied by tilted-ring modeling of the velocities of interstellar material. These kinematics must trace galactic fountain flows and demonstrate that they persist at R_perp > 5 kpc. Finally, we assess the relationship between dust reddening and W_r(CaII K) (W_r(NaI 5891)), finding that 33% (24%) of the absorbers are inconsistent with the best-fit Milky Way E(B-V)-W_r relations at >3sigma significance.Comment: 38 pages, 16 figures, 4 tables. Accepted to Ap

A translational framework for public health research

&lt;p&gt;&lt;b&gt;Background&lt;/b&gt;&lt;/p&gt; &lt;p&gt;The paradigm of translational medicine that underpins frameworks such as the Cooksey report on the funding of health research does not adequately reflect the complex reality of the public health environment. We therefore outline a translational framework for public health research.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Discussion&lt;/b&gt;&lt;/p&gt; &lt;p&gt;Our framework redefines the objective of translation from that of institutionalising effective interventions to that of improving population health by influencing both individual and collective determinants of health. It incorporates epidemiological perspectives with those of the social sciences, recognising that many types of research may contribute to the shaping of policy, practice and future research. It also identifies a pivotal role for evidence synthesis and the importance of non-linear and intersectoral interfaces with the public realm.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Summary&lt;/b&gt;&lt;/p&gt; &lt;p&gt;We propose a research agenda to advance the field and argue that resources for 'applied' or 'translational' public health research should be deployed across the framework, not reserved for 'dissemination' or 'implementation'.&lt;/p&gt

Gas Accretion via Lyman Limit Systems

In cosmological simulations, a large fraction of the partial Lyman limit systems (pLLSs; 16<log N(HI)<17.2) and LLSs (17.2log N(HI)<19) probes large-scale flows in and out of galaxies through their circumgalactic medium (CGM). The overall low metallicity of the cold gaseous streams feeding galaxies seen in these simulations is the key to differentiating them from metal rich gas that is either outflowing or being recycled. In recent years, several groups have empirically determined an entirely new wealth of information on the pLLSs and LLSs over a wide range of redshifts. A major focus of the recent research has been to empirically determine the metallicity distribution of the gas probed by pLLSs and LLSs in sizable and representative samples at both low (z2) redshifts. Here I discuss unambiguous evidence for metal-poor gas at all z probed by the pLLSs and LLSs. At z<1, all the pLLSs and LLSs so far studied are located in the CGM of galaxies with projected distances <100-200 kpc. Regardless of the exact origin of the low-metallicity pLLSs/LLSs, there is a significant mass of cool, dense, low-metallicity gas in the CGM that may be available as fuel for continuing star formation in galaxies over cosmic time. As such, the metal-poor pLLSs and LLSs are currently among the best observational evidence of cold, metal-poor gas accretion onto galaxies.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by Springe

The Connection between a Lyman Limit System, a very strong OVI Absorber, and Galaxies at z~0.203

With a column density log N(OVI) = 14.95+/-0.05, the OVI absorber at z_abs~0.2028 observed toward the QSO PKS0312-77 (z_em=0.223) is the strongest yet detected at z<0.5. At nearly identical redshift (z_abs=0.2026), we also identify a Lyman limit system (LLS, log N(HI)=18.22). Combining FUV and NUV spectra of PKS0312-77 with optical observations of galaxies in the surrounding field (15'x32'), we present an analysis of these absorbers and their connection to galaxies. The observed OI/HI ratio and photoionization modelling of other low ions indicate the metallicity of the LLS is [Z/H]_LLS=-0.6 and that the LLS is nearly 100% photoionized. In contrast, the OVI-bearing gas is collisionally ionized at T~(3-10)x10^5 K as derived from the high-ion ratios and profile broadenings. Our galaxy survey reveals 13 (0.3<L/L*<1.6) galaxies at \rho<2 h^{-1}_{70} Mpc and |\delta v|<1100 km/s from the LLS. A probable origin for the LLS is debris from a galaxy merger, which led to a 0.7L* galaxy ([Z/H]_gal=+0.15) at\rho~38 h^{-1}_{70} kpc. Outflow from this galaxy may also be responsible for the supersolar ([Z/H]_abs=+0.15), fully ionized absorber at z_abs=0.2018 (-190 km/s from the LLS). The hot OVI absorber likely probes coronal gas about the 0.7 L* galaxy and/or (~0.1 keV) intragroup gas of a spiral-rich system. The association of other strong OVI absorbers with LLS suggests they trace galactic and not intergalactic structures.Comment: Accepted for publication in the Ap

Gas Accretion in Star-Forming Galaxies

Cold-mode gas accretion onto galaxies is a direct prediction of LCDM simulations and provides galaxies with fuel that allows them to continue to form stars over the lifetime of the Universe. Given its dramatic influence on a galaxy's gas reservoir, gas accretion has to be largely responsible for how galaxies form and evolve. Therefore, given the importance of gas accretion, it is necessary to observe and quantify how these gas flows affect galaxy evolution. However, observational data have yet to conclusively show that gas accretion ubiquitously occurs at any epoch. Directly detecting gas accretion is a challenging endeavor and we now have obtained a significant amount of observational evidence to support it. This chapter reviews the current observational evidence of gas accretion onto star-forming galaxies.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by Springer. This chapter includes 22 pages with 7 Figure

Applied public health research - falling through the cracks?

<p>Abstract</p> <p>Background</p> <p>There is a degree of dissonance between the types of evaluative research required by organisations providing or commissioning health care, those recommended by organisations developing evidence-based guidance, and those which research funding bodies are prepared to support.</p> <p>Methods</p> <p>We present a case study of efforts to establish a pragmatic but robust evaluation of local exercise referral schemes. We considered the epidemiological, ethical and practical advantages and disadvantages of a number of study designs and applied for research funding based on an uncontrolled design, outlining the difficulties of carrying out a randomised controlled trial to evaluate an existing service.</p> <p>Results</p> <p>Our proposal was praised for its relevance and clear patient outcomes, but the application was twice rejected because both funders and reviewers insisted on a randomised controlled trial design, which we had found to be impractical, unacceptable to service users and potentially unethical.</p> <p>Conclusion</p> <p>The case study highlights continuing challenges for applied public health research in the current funding climate.</p

Gravity Amplitudes from a Gaussian Matrix Model

We reformulate MHV scattering amplitudes in 4D gauge theory and supergravity as correlation functions of bilinear operators in a supersymmetric gaussian matrix model. The model retains the symmetries of an S(4) of radius L and the matrix variables are represented as linear operators acting on a finite-dimensional Hilbert space. Bilinear fields of the model generate a current algebra. In the large N double scaling limit where l_pl ~ L / sqrt(N) is held fixed, there is an emergent flat 4D space-time with a built in short distance cutoff.Comment: v3: 55 pages, 4 figures, clarifications adde