Polarization Observations with the Cosmic Background Imager

We describe polarization observations of the CMBR with the Cosmic Background Imager, a 13 element interferometer which operates in the 26-36 GHz band from Llano de Chajnantour in northern Chile. The array consists of 90-cm Cassegrain antennas mounted on a steerable platform which can be rotated about the optical axis to facilitate polarization observations. The CBI employs single mode circularly polarized receivers which sample multipoles from ℓ~400 to ℓ~4250. The instrumental polarization of the CBI was calibrated with 3C279, a bright polarized point source which was monitored with the VLA

A Multi-wavelength Study of the Host Environment of SMBHB 4C+37.11

4C+37.11, at z=0.055 shows two compact radio nuclei, imaged by VLBI at 7mas separation, making it the closest known resolved super-massive black hole binary (SMBHB). An important question is whether this unique object is young, caught on the way to a gravitational in-spiral and merger, or has `stalled' at 7pc. We describe new radio/optical/X-ray observations of the massive host and its surrounding X-ray halo. These data reveal X-ray/optical channels following the radio outflow and large scale edges in the X-ray halo. These structures are promising targets for further study which should elucidate their relationship to the unique SMBHB core.Comment: To appear in the Astrophysical Journa

VLBI and Archival VLA and WSRT Observations of the GRB 030329 Radio Afterglow

We present VLBI and archival Karl G. Jansky Very Large Array (VLA) and Westerbork Synthesis Radio Telescope (WSRT) observations of the radio afterglow from the gamma-ray burst (GRB) of 2003 March 29 (GRB 030329) taken between 672 and 2032 days after the burst. The EVLA and WSRT data suggest a simple power law decay in the flux at 5 GHz, with no clear signature of any rebrightening from the counter jet. We report an unresolved source at day 2032 of size $1.18\pm0.13$ mas, which we use in conjunction with the expansion rate of the burst to argue for the presence of a uniform, ISM-like circumburst medium. We develop a semi-analytic method to model gamma-ray burst afterglows, and apply it to the 5 GHz light curve to perform burst calorimetry. A limit of $< 0.067$ mas yr$^{-1}$ is placed on the proper motion, supporting the standard afterglow model for gamma-ray bursts.Comment: 24 pages, 5 figure

Vaccinating sons against HPV: results from a U.S. national survey of parents

PURPOSE: The quadrivalent HPV vaccination was approved for use in males ages 9 to 26 in 2009 and recommended for routine administration in 2011. The purpose of this study was to uncover predictable commonalities amongst parents who chose to vaccinate their 11-17 year old sons against HPV. METHODS: We compiled data from a U.S. national sample of 779 parents with sons 11-17 years old using a web-based survey to gather information about behavioral and sociodemographic factors which predicted receipt of 1 or more HPV vaccine doses based on parental report. Predictors were first modeled individually for univariable associations. Significant predictors (p<0.10) were combined in a multivariable model. RESULTS: In the adjusted model, independent predictors included receipt of flu vaccination, health insurance coverage and sexual health topic discussions with sons. Sons who had received a flu shot in the last two years more frequently received at least one dose of the vaccine (OR 1.82; 95% CI 1.45-2.26). Sons covered by private health insurance had decreased odds of HPV vaccination (OR 0.56 95% CI 0.37-0.83). Lastly, parents who had discussed sexual health topics with their sons were more likely to vaccinate (OR 1.61; 95% CI 1.37-1.89). CONCLUSIONS: Male vaccination rates in the U.S. have increased, but males continue to be under-immunized. Utilization of health care is an important factor in HPV vaccine uptake; therefore, health care providers should use every contact as an opportunity to vaccinate. Communication about sexual health topics may provide a forum for parents and health care providers to have conversations about HPV vaccination as those more comfortable discussing these topics may also be more comfortable discussing HPV vaccination

Are the Faraday Rotating Magnetic Fields Local to Intracluster Radio Galaxies?

We investigate the origin of the high Faraday rotation measures (RMs) found for polarized radio galaxies in clusters. The two most likely origins are, magnetic fields local to the source, or magnetic fields located in the foreground intra-cluster medium (ICM). The latter is identified as the null hypothesis. Rudnick & Blundell (2003) have recently suggested that the presence of magnetic fields local to the source may be revealed in correlations of the position angles (PAs) of the source intrinsic linear polarization and the RMs. We investigate the claim of Rudnick & Blundell to have found a relationship between the intrinsic PA0 of the radio source PKS 1246-410 and its RM, by testing the clustering strength of the PA0-RM scatter plot. We show that the claimed relationship is an artifact of an improperly performed null-experiment. We describe a gradient alignment statistic aimed at finding correlations between PA0 and RM maps. This statistic does not require any null-experiment since it gives a unique (zero) result in the case of uncorrelated maps. We apply it to a number of extended radio sources in galaxy clusters (PKS 1246-410, Cygnus A, Hydra A, and 3C465). In no case is a significant large-scale alignment of PA0 and RM maps detected. We find significant small-scale co-alignment in all cases, but we are able to fully identify this with map making artifacts through a suitable statistical test. We conclude that there is presently no existing evidence for Faraday rotation local to radio lobes. Given the existing independent pieces of evidence, we favor the null hypothesis that the observed Faraday screens are produced by intracluster magnetic fields.Comment: accepted by ApJ, 8 pages, 1 figure, minor style improvement