The Space Density of Compton-thick AGN

We constrain the number density and evolution of Compton-thick Active Galactic Nuclei (AGN), and their contribution to the extragalactic X-ray background. In the local Universe we use the wide area surveys from the Swift and INTEGRAL satellites, while for high redshifts we explore candidate selections based on mid-IR parameters. We present the properties of a sample of 211 heavily-obscured AGN candidates in the Extended Chandra Deep Field-South (ECDF-S) selecting objects with f24/fR>1000 and R-K>4.5. The X-ray to mid-IR ratios for these sources are significantly larger than that of star-forming galaxies and ~2 orders of magnitude smaller than for the general AGN population, suggesting column densities of NH>5x10^24 cm^-2. The space density of CT AGN at z~2 derived from these observations is ~10^-5 Mpc^{-3}, finding a strong evolution in the number of LX>10^44 erg/s sources from z=1.5 to 2.5.Comment: 4 pages, 3 figures, to appear in proceedings for 'X-ray Astronomy 2009', Bologna 09/2009, AIP Conference Series, Eds. A. Comastri, M. Cappi, L. Angelini; author list fixe

Cardiac Resynchronization Therapy in the Cardiorenal Syndrome

The cardiorenal syndrome (CRS) is a complex clinical syndrome in which dysfunction of either the heart or the kidneys affects the functioning of the other organ system. Many therapies used in heart failure have further detrimental effects on renal function. Cardiac resynchronization therapy (CRT) is a relatively new form of device therapy that reduces morbidity and mortality in patients with heart failure. This review will discuss the effects of CRT on renal function in patients with CRS, the impact of baseline renal function on response to CRT, and potential risks associated with CRT in this unique population

Patient-reported reasons for declining or discontinuing statin therapy: Insights from the PALM registry

Background: Many adults eligible for statin therapy for cardiovascular disease prevention are untreated. Our objective was to investigate patient‐reported reasons for statin underutilization, including noninitiation, refusal, and discontinuation.Methods and Results: This study included the 5693 adults recommended for statin therapy in the PALM (Patient and Provider Assessment of Lipid Management) registry. Patient surveys evaluated statin experience, reasons for declining or discontinuing statins, and beliefs about statins and cardiovascular disease risk. Overall, 1511 of 5693 adults (26.5%) were not on treatment. Of those not on a statin, 894 (59.2%) reported never being offered a statin, 153 (10.1%) declined a statin, and 464 (30.7%) had discontinued therapy. Women (relative risk: 1.22), black adults (relative risk: 1.48), and those without insurance (relative risk: 1.38) were most likely to report never being offered a statin. Fear of side effects and perceived side effects were the most common reasons cited for declining or discontinuing a statin. Compared with statin users, those who declined or discontinued statins were less likely to believe statins are safe (70.4% of current users vs. 36.9% of those who declined and 37.4% of those who discontinued) or effective (86.3%, 67.4%, and 69.1%, respectively). Willingness to take a statin was high; 67.7% of those never offered and 59.7% of patients who discontinued a statin would consider initiating or retrying a statin.Conclusions: More than half of patients eligible for statin therapy but not on treatment reported never being offered one by their doctor. Concern about side effects was the leading reason for statin refusal or discontinuation. Many patients were willing to reconsider statin therapy if offered

Creative Hubs and Urban Development Goals: Policy Report

This report highlights the key policy implications of the AHRC-funded research and knowledge exchange project, 'Creative Hubs and Urban Development Goals: (UK/Brazil)' for the funding and design of creative hubs in the State of São Paul

The Chandra X-ray Observatory Resolves the X-ray Morphology and Spectra of a Jet in PKS 0637-752

The core-dominated radio-loud quasar PKS 0637-752 (z = 0.654) was the first celestial object observed with the Chandra X-ray Observatory, offering the early surprise of the detection of a remarkable X-ray jet. Several observations with a variety of detector configurations contribute to a total exposure time with the Chandra Advanced CCD Imaging Spectrometer (ACIS; Garmire et al. 2000, in preparation) of about 100ks. A spatial analysis of all the available X-ray data, making use of Chandra's spatial resolving power of about 0.4 arcsec, reveals a jet that extends about 10 arcsec to the west of the nucleus. At least four X-ray knots are resolved along the jet, which contains about 5% of the overall X-ray luminosity of the source. Previous observations of PKS 0637-752 in the radio band (Tingay et al. 1998) had identified a kpc-scale radio jet extending to the West of the quasar. The X-ray and radio jets are similar in shape, intensity distribution, and angular structure out to about 9 arcsec, after which the X-ray brightness decreases more rapidly and the radio jet turns abruptly to the north. The X-ray luminosity of the total source is log Lx ~ 45.8 erg/s (2 - 10keV), and appears not to have changed since it was observed with ASCA in November 1996. We present the results of fitting a variety of emission models to the observed spectral distribution, comment on the non-existence of emission lines recently reported in the ASCA observations of PKS 0637-752, and briefly discuss plausible X-ray emission mechanisms.Comment: 24 pages, includes 8 figures, Accepted for publication in Ap

Chandra Discovery of a 100 kpc X-ray Jet in PKS 0637--752

The quasar PKS 0637-753, the first celestial X-ray target of the Chandra X-ray Observatory, has revealed asymmetric X-ray structure extending from 3 to 12 arcsec west of the quasar, coincident with the inner portion of the jet previously detected in a 4.8 GHz radio image (Tingay et al. 1998). At a redshift of z=0.651, the jet is the largest (~100 kpc) and most luminous (~10^{44.6} ergs/s) of the few so far detected in X-rays. This letter presents a high resolution X-ray image of the jet, from 42 ks of data when PKS 0637-753 was on-axis and ACIS-S was near the optimum focus. For the inner portion of the radio jet, the X-ray morphology closely matches that of new ATCA radio images at 4.8 and 8.6 GHz. Observations of the parsec scale core using the VSOP space VLBI mission show structure aligned with the X-ray jet, placing important constraints on the X-ray source models. HST images show that there are three small knots coincident with the peak radio and X-ray emission. Two of these are resolved, which we use to estimate the sizes of the X-ray and radio knots. The outer portion of the radio jet, and a radio component to the east, show no X-ray emission to a limit of about 100 times lower flux. The X-ray emission is difficult to explain with models that successfully account for extra-nuclear X-ray/radio structures in other active galaxies. We think the most plausible is a synchrotron self-Compton (SSC) model, but this would imply extreme departures from the conventional minimum-energy and/or homogeneity assumptions. We also rule out synchrotron or thermal bremsstrahlung models for the jet X-rays, unless multicomponent or ad hoc geometries are invoked.Comment: 5 Pages, 2 Figures. Submitted to Ap. J. Letter

The Extended Chandra Deep Field-South Survey: X-ray Point-Source Catalog

The Extended Chandra Deep Field-South (ECDFS) survey consists of 4 Chandra ACIS-I pointings and covers $\approx$ 1100 square arcminutes ($\approx$ 0.3 deg$^2$) centered on the original CDF-S field to a depth of approximately 228 ks. This is the largest Chandra survey ever conducted at such depth, and only one XMM-Newton survey reaches a lower flux limit in the hard 2.0--8.0 keV band. We detect 651 unique sources -- 587 using a conservative source detection threshold and 64 using a lower source detection threshold. These are presented as two separate catalogs. Of the 651 total sources, 561 are detected in the full 0.5--8.0 keV band, 529 in the soft 0.5--2.0 keV band, and 335 in the hard 2.0--8.0 keV band. For point sources near the aim point, the limiting fluxes are approximately $1.7 \times 10^{-16}$ $\rm{erg cm^{-2} s^{-1}}$ and $3.9 \times 10^{-16}$ $\rm{erg cm^{-2} s^{-1}}$ in the 0.5--2.0 keV and 2.0--8.0 keV bands, respectively. Using simulations, we determine the catalog completeness as a function of flux and assess uncertainties in the derived fluxes due to incomplete spectral information. We present the differential and cumulative flux distributions, which are in good agreement with the number counts from previous deep X-ray surveys and with the predictions from an AGN population synthesis model that can explain the X-ray background. In general, fainter sources have harder X-ray spectra, consistent with the hypothesis that these sources are mainly obscured AGN.Comment: Replaced original paper with the AJ-accepted version. New version includes simulations on the uncertainties in the derived fluxes due to incomplete spectral information and catalog completeness. Full catalog available at http://www.astro.yale.edu/svirani/ecdfs