The Discovery of a Large Lyman-alpha+HeII Nebula at z~1.67: A Candidate Low Metallicity Region?

We have discovered a ~45 kpc Lya nebula (or Lya ``blob'') at z~1.67 which exhibits strong, spatially-extended HeII emission and very weak CIV and CIII] emission. This is the first spatially-extended Lya+HeII emitter observed and the lowest redshift Lya blob yet found. Strong Lya and HeII-1640 emission in the absence of metal lines has been proposed as a unique observational signature of primordial galaxy formation (e.g., from gravitational cooling radiation or Population III star formation), but no convincing examples of spatially-extended Lya+HeII emitters have surfaced either in Lya-emitting galaxy surveys at high redshifts (z > 4) or in studies of Lya nebulae at lower redshifts. From comparisons with photoionization models, we find that the observed line ratios in this nebula are consistent with low metallicity gas (Z < 10^-2 - 10^-3 Z_sun), but that this conclusion depends on the unknown ionization parameter of the system. The large HeII equivalent width (~37+/-10A) and the large HeII/Lya ratio (0.12+/-0.04) suggest that the cloud is being illuminated by a hard ionizing continuum, either an AGN or very low metallicity stars, or perhaps powered by gravitational cooling radiation. Thus far there is no obvious sign of a powerful AGN in or near the system, so in order to power the nebula while remaining hidden from view even in the mid-infrared, the AGN would need to be heavily obscured. Despite the strong Lya+HeII emission, it is not yet clear what is the dominant power source for this nebula. The system therefore serves as an instructive example of how the complexities of true astrophysical sources will complicate matters when attempting to use a strong Lya+HeII signature as a unique tracer of primordial galaxy formation.Comment: Accepted for publication in ApJ; emulateapj format, 17 pages, 7 figures, 3 tables; updated coordinate

Testing a Spanish-language colorectal cancer screening decision aid in Latinos with limited English proficiency: Results from a pre-post trial and four month follow-up survey

Abstract Background Compared with non-Latinos, Latinos in the US have low rates of colorectal cancer (CRC) screening and low rates of knowledge regarding CRC screening tests and guidelines. Spanish speaking Latinos have particularly low CRC screening rates and screening knowledge. Our purpose was twofold: (1) to evaluate the effect of a computer-based, Spanish-language CRC screening decision aid on screening knowledge, intent to obtain screening, and screening self-efficacy in a community sample of Latinos with limited English proficiency (LEP); and (2) to survey these decision aid viewers at four months to determine their rates of CRC discussions with a health care provider as well as their rates of screening test completion. Methods We recruited 50-75 year old Latinos with LEP who were not current with CRC. Participants screening viewed a 14 minute multimedia decision aid that addresses CRC screening rationale, recommendations, and options. We conducted an uncontrolled (pre-post) study in which we assessed screening knowledge, self-efficacy, and intent at baseline and immediately after decision aid viewing. We also conducted a follow-up telephone survey of participants at four months to examine rates of patient-provider screening discussions and test completion. Results Among n = 80 participants, knowledge scores increased from 20% (before) to 72% (after) decision aid viewing (absolute difference [95%CI]: 52% [46, 59]). The proportion with high screening self-efficacy increased from 67% to 92% (25% [13, 37]); the proportion with high screening intent increased from 63% to 95% (32% [21, 44]). We reached 68 (85%) of 80 participants eligible for the follow-up survey. Of these 36 (53%) reported discussing screening with a provider and 13 (19%) completed a test. Conclusion Viewing a Spanish-language decision aid increased CRC screening knowledge, self-efficacy, and intent among Latinos with LEP. Decision aid viewing appeared to promote both CRC screening discussions with health care providers and test completion. The decision aid may be an effective tool for promoting CRC screening and reducing screening disparities in this population

Cultural and Linguistic Adaptation of a Multimedia Colorectal Cancer Screening Decision Aid for Spanish-Speaking Latinos

As the United States becomes more linguistically and culturally diverse, there is a need for effective health communication interventions that target diverse and most vulnerable populations. Latinos also have the lowest colorectal (CRC) screening rates of any ethnic group in the U.S. To address such disparities, health communication interventionists are often faced with the challenge to adapt existing interventions from English into Spanish in a way that retains essential elements of the original intervention while also addressing the linguistic needs and cultural perspectives of the target population. We describe the conceptual framework, context, rationale, methods, and findings of a formative research process used in creating a Spanish language version of an evidenced-based (English language) multimedia CRC screening decision aid. Our multi-step process included identification of essential elements of the existing intervention, literature review, assessment of the regional context and engagement of key stakeholders, and solicitation of direct input from target population. We integrated these findings in the creation of the new adapted intervention. We describe how we used this process to identify and integrate socio-cultural themes such as personalism (personalismo), familism (familismo), fear (miedo), embarrassment (verguenza), power distance (respeto), machismo, and trust (confianza) into the Spanish language decision aid

The relationship between the optical Halpha filaments and the X-ray emission in the core of the Perseus cluster

NGC 1275 in the centre of the Perseus cluster of galaxies, Abell 426, is surrounded by a spectacular filamentary Halpha nebula. Deep Chandra X-ray imaging has revealed that the brighter outer filaments are also detected in soft X-rays. This can be due to conduction and mixing of the cold gas in the filaments with the hot, dense intracluster medium. We show the correspondence of the filaments in both wavebands and draw attention to the relationship of two prominent curved NW filaments to an outer, buoyant radio bubble seen as a hole in the X-ray image. There is a strong resemblance in the shape of the hole and the disposition of the filaments to the behaviour of a large air bubble rising in water. If this is a correct analogy, then the flow is laminar and the intracluster gas around this radio source is not turbulent. We obtain a limit on the viscosity of this gas.Comment: Accepted for publication in MNRA

Patient Decision Aids for Colorectal Cancer Screening

Decision aids (DAs) prepare patients to make decisions about healthcare options consistent with their preferences. Helping patients choose among available options for colorectal cancer (CRC) screening is important because rates are lower than screening for other cancers. This systematic review describes studies evaluating patient DAs for CRC screening in average-risk adults and their impact on knowledge, screening intentions, and uptake

HST/ACS Emission Line Imaging of Low Redshift 3CR Radio Galaxies I: The Data

We present 19 nearby (z<0.3) 3CR radio galaxies imaged at low- and high-excitation as part of a Cycle 15 Hubble Space Telescope snapshot survey with the Advanced Camera for Surveys. These images consist of exposures of the H-alpha (6563 \AA, plus [NII] contamination) and [OIII] 5007 \AA emission lines using narrow-band linear ramp filters adjusted according to the redshift of the target. To facilitate continuum subtraction, a single-pointing 60 s line-free exposure was taken with a medium-band filter appropriate for the target's redshift. We discuss the steps taken to reduce these images independently of the automated recalibration pipeline so as to use more recent ACS flat-field data as well as to better reject cosmic rays. We describe the method used to produce continuum-free (pure line-emission) images, and present these images along with qualitative descriptions of the narrow-line region morphologies we observe. We present H-alpha+[NII] and [OIII] line fluxes from aperture photometry, finding the values to fall expectedly on the redshift-luminosity trend from a past HST/WFPC2 emission line study of a larger, generally higher redshift subset of the 3CR. We also find expected trends between emission line luminosity and total radio power, as well as a positive correlation between the size of the emission line region and redshift. We discuss the associated interpretation of these results, and conclude with a summary of future work enabled by this dataset.Comment: 18 pages, 12 figures, accepted for publication in ApJ

A New Population of High Redshift, Dusty Lyman-Alpha Emitters and Blobs Discovered by WISE

We report a new technique to select 1.6<z<4.6 dusty Lyman-alpha emitters (LAEs), over a third of which are `blobs' (LABs) with emission extended on scales of 30-100kpc. Combining data from the NASA Wide-field Infrared Survey Explorer (WISE) mission with optical spectroscopy from the W.M. Keck telescope, we present a color criteria that yields a 78% success rate in identifying rare, dusty LAEs of which at least 37% are LABs. The objects have a surface density of only ~0.1 per square degree, making them rare enough that they have been largely missed in narrow surveys. We measured spectroscopic redshifts for 92 of these WISE-selected, typically radio-quiet galaxies and find that the LAEs (LABs) have a median redshift of 2.3 (2.5). The WISE photometry coupled with data from Herschel reveals that these galaxies have extreme far-infrared luminosities (L_IR>10^{13-14}L_sun) and warm colors, typically larger than submillimeter-selected galaxies (SMGs) and dust-obscured galaxies (DOGs). These traits are commonly associated with the dust being energized by intense AGN activity. We hypothesize that the combination of spatially extended Lyman-alpha, large amounts of warm IR-luminous dust, and rarity (implying a short-lived phase) can be explained if the galaxies are undergoing strong `feedback' transforming them from an extreme dusty starburst to a QSO.Comment: Submitted to ApJ Letters, 6 pages, 4 figures. Comments welcom

Gas Accretion and Giant Lyman-alpha Nebulae

Several decades of observations and discoveries have shown that high-redshift AGN and massive galaxies are often surrounded by giant Lyman-alpha nebulae extending in some cases up to 500 kpc in size. In this review, I discuss the properties of the such nebulae discovered at z>2 and their connection with gas flows in and around the galaxies and their halos. In particular, I show how current observations are used to constrain the physical properties and origin of the emitting gas in terms of the Lyman-alpha photon production processes and kinematical signatures. These studies suggest that recombination radiation is the most viable scenario to explain the observed Lyman-alpha luminosities and Surface Brightness for the large majority of the nebulae and imply that a significant amount of dense, ionized and cold clumps should be present within and around the halos of massive galaxies. Spectroscopic studies suggest that, among the giant Lyman-alpha nebulae, the one associated with radio-loud AGN should have kinematics dominated by strong, ionized outflows within at least the inner 30-50 kpc. Radio-quiet nebulae instead present more quiescent kinematics compatible with stationary situation and, in some cases, suggestive of rotating structures. However, definitive evidences for accretion onto galaxies of the gas associated with the giant Lyman-alpha emission are not unambiguously detected yet. Deep surveys currently ongoing using other bright, non-resonant lines such as Hydrogen H-alpha and HeII1640 will be crucial to search for clearer signatures of cosmological gas accretion onto galaxies and AGN.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dave', to be published by Springe

Properties of Ly-alpha emitters around the radio galaxy MRC 0316-257

Observations of the radio galaxy MRC 0316-257 at z=3.13 and the surrounding field are presented. Using narrow- and broad-band imaging obtained with the VLT, 77 candidate Ly-alpha emitters with a rest-frame equivalent width of > 15 A were selected in a ~7'x7' field around the radio galaxy. Spectroscopy of 40 candidate emitters resulted in the discovery of 33 emission line galaxies of which 31 are Ly-alpha emitters with redshifts similar to that of the radio galaxy, while the remaining two galaxies turned out to be [OII] emitters. The Ly-alpha profiles have widths (FWHM) in the range of 120-800 km/s, with a median of 260 km/s. Where the signal-to-noise was large enough, the Ly-alpha profiles were found to be asymmetric, with apparent absorption troughs blueward of the profile peaks, indicative of absorption along the line of sight of an HI mass of at least 2x10^2 - 5x10^4 M_sun. The properties of the Ly-alpha galaxies (faint, blue and small) are consistent with young star forming galaxies which are still nearly dust free. The volume density of Ly-alpha emitting galaxies in the field around MRC 0316-257 is a factor of 3.3+0.5-0.4 larger compared with the density of field Ly-alpha emitters at that redshift. The velocity distribution of the spectroscopically confirmed emitters has a FWHM of 1510 km/s, which is substantially smaller than the width of the narrow-band filter (FWHM ~ 3500 km/s). The peak of the velocity distribution is located within 200 km/s of the redshift of the radio galaxy. We conclude that the confirmed Ly-alpha emitters are members of a protocluster of galaxies at z~3.13. The size of the protocluster is larger than 3.3x3.3 Mpc^2. The mass of this structure is estimated to be > 3-6x10^14 M_sun and could be the progenitor of a cluster of galaxies similar to e.g. the Virgo cluster. (Abridged)Comment: 23 Pages, including 20 PostScript figures. Publiced in Astronomy & Astrophysics. v2: typo fixed and Journal reference adde

Do Physicians with Self-Reported Non-English Fluency Practice in Linguistically Disadvantaged Communities?

BackgroundLanguage concordance between physicians and patients may reduce barriers to care faced by patients with limited English proficiency (LEP). It is unclear whether physicians with fluency in non-English languages practice in areas with high concentrations of people with LEP.ObjectiveTo investigate whether physician non-English language fluency is associated with practicing in areas with high concentrations of people with LEP.DesignCross-sectional cohort study.ParticipantsA total of 61,138 practicing physicians no longer in training who participated in the California Medical Board Physician Licensure Survey from 2001-2007.MeasuresSelf-reported language fluency in Spanish and Asian languages. Physician practice ZIP code corresponding to: (1) high concentration of people with LEP and (2) high concentration of linguistically isolated households.MethodsPractice location ZIP code was geocoded with geographic medical service study designations. We examined the unadjusted relationships between physician self-reported fluency in Spanish and selected Asian languages and practice location, stratified by race-ethnicity. We used staged logistic multiple variable regression models to isolate the effect of self-reported language fluency on practice location controlling for age, gender, race-ethnicity, medical specialty, and international medical graduate status.ResultsPhysicians with self-reported fluency in Spanish or an Asian language were more likely to practice in linguistically designated areas in these respective languages compared to those without fluency. Physician fluency in an Asian language [adjusted odds ratio (AOR) = 1.77; 95% confidence intervals (CI): 1.63-1.92] was independently associated with practicing in areas with a high number of LEP Asian speakers. A similar pattern was found for Spanish language fluency (AOR = 1.77; 95% CI: 1.43-1.82) and areas with high numbers of LEP Spanish-speakers. Latino and Asian race-ethnicity had the strongest effect on corresponding practice location, and this association was attenuated by language fluency.ConclusionsPhysicians who are fluent in Spanish or an Asian language are more likely to practice in geographic areas where their potential patients speak the corresponding language