Old and Young X-ray Point Source Populations in Nearby Galaxies

We analyzed 1441 Chandra X-ray point sources in 32 nearby galaxies. The total point-source X-ray luminosity L_XP is well correlated with B, K, and FIR+UV luminosities of spiral host galaxies, and with the B and K luminosities for ellipticals. This suggests an intimate connection between L_XP and both the old and young stellar populations, for which K and FIR+UV luminosities are proxies for the galaxy mass M and star-formation rate SFR. We derive proportionality constants 1.3E29 erg/s/Msol and 0.7E39 erg/s/(Msol/yr), which can be used to estimate the old and young components from M and SFR, respectively. The cumulative X-ray luminosity functions for the point sources have quite different slopes for the spirals (gamma ~= 0.5-0.8) and ellipticals (gamma ~= 1.4), implying *the most luminous point sources dominate L_XP* for the spirals. Most of the point sources have X-ray colors that are consistent with either LMXBs or Ultraluminous X-ray sources (ULXs a.k.a. IXOs) and we rule out classical HMXBs (e.g. neutron-star X-ray pulsars) as contributing much to L_XP. Thus, for spirals, the ULXs dominate L_XP. We estimate that >~20% of all ULXs found in spirals originate from the older (pop II) stellar populations, indicating that many of the ULXs that have been found in spiral galaxies are in fact pop II ULXs, like those in elliptical galaxies. The linear dependence of L_XP on the SFR argues for either a steepening in the X-ray luminosity function of the young (pop I) X-ray source population at L_X >~10^(38.5-39) erg/s, or a decreasing efficiency for producing all types of young X-ray point sources as the galaxy SFR increases.Comment: 33 pages AASTEX, ApJ accepted. Please download full version with figures from http://www.pha.jhu.edu/~colbert/chps_accepted.p

Extranuclear X-ray Emission in the Edge-on Seyfert Galaxy NGC 2992

We found several extranuclear (r >~ 3") X-ray nebulae within 40" (6.3 kpc at 32.5 Mpc) of the nucleus of the Seyfert galaxy NGC 2992. The net X-ray luminosity from the extranuclear sources is ~2-3 E39 erg/s (0.3-8.0 keV). The X-ray core itself (r <~ 1") is positioned at 9:45:41.95 -14:19:34.8 (J2000) and has a remarkably simple power-law spectrum with photon index Gamma=1.86 and Nh=7E21 /cm2. The near-nuclear (3" <~ r <~ 18") Chandra spectrum is best modelled by three components: (1) a direct AGN component with Gamma fixed at 1.86, (2) cold Compton reflection of the AGN component, and (3) a 0.5 keV low-abundance (Z < 0.03 Zsolar) "thermal plasma," with ~10% of the flux of either of the first two components. The X-ray luminosity of the 3rd component (the "soft excess") is ~1.4E40 erg/s, or ~5X that of all of the detected extranuclear X-ray sources. We suggest that most (~75-80%) of the soft excess emission originates from 1" < r < 3", which is not imaged in our observation due to severe CCD pile-up. We also require the cold reflector to be positioned at least 1" (158 pc) from the nucleus, since there is no reflection component in the X-ray core spectrum. Much of the extranuclear X-ray emission is coincident with radio structures (nuclear radio bubbles and large-scale radio features), and its soft X-ray luminosity is generally consistent with luminosities expected from a starburst-driven wind (with the starburst scaled from L_FIR). However, the AGN in NGC 2992 seems equally likely to power the galactic wind in that object. Furthermore, AGN photoionization and photoexcitation processes could dominate the soft excess, especially the \~75-80% which is not imaged by our observations.Comment: 34 pages AASTEX, 9 (low-res) PS figures, ApJ, in press. For full-resolution postscript file, visit http://www.pha.jhu.edu/~colbert/n2992_chandra.ps.g

The X-ray Reflectors in the Nucleus of the Seyfert Galaxy NGC 1068

(abridged) Based on observations of the Seyfert nucleus in NGC1068 with ASCA, RXTE and BeppoSAX, we report the discovery of a flare (increase in flux by a factor of ~1.6) in the 6.7 keV Fe K line component between observations obtained 4 months apart, with no significant change in the other (6.21, 6.4, and 6.97 keV) Fe K_alpha line components. During this time, the continuum flux decreased by ~20%. The RXTE spectrum requires an Fe K absorption edge near 8.6 keV (Fe XXIII - XXV). The spectral data indicate that the 2-10 keV continuum emission is dominated (~2/3 of the luminosity) by reflection from a previously unidentified region of warm, ionized gas located <~ 0.2 pc from the AGN. The remaining ~1/3 of the observed X-ray emission is reflected from optically thick, neutral gas. The inferred properties of the warm reflector (WR) are: size (diameter) ~ 10^{5.5} /cm3, ionization parameter xi approx 10^{3.5} erg cm/s, and covering fraction 0.003 (L_0/10^{43.5} erg/s)^{-1} < (Omega/4 pi) < 0.024 (L_0/10^{43.5})^{-1}, where L_0 is the intrinsic 2-10 keV X-ray luminosity of the AGN. We suggest that the WR gas is the source of the (variable) 6.7 keV Fe line emission, and the 6.97 keV Fe line emission. The 6.7 keV line flare is assumed to be due to an increase in the emissivity of the WR gas from a decrease (by 20-30%) in L_0. The properties of the WR are most consistent with an intrinsically X-ray weak AGN with L_0 approx 10^{43.0} erg/s. The optical and UV emission that scatters from the WR into our line of sight is required to suffer strong extinction, which can be reconciled if the line-of-sight skims the outer surface of the torus. Thermal bremsstrahlung radio emission from the WR may be detectable in VLBA radio maps of the NGC 1068 nucleus.Comment: 39 pages (9 postscript figures) AASTEX, ApJ, accepte

FAK activity sustains intrinsic and acquired ovarian cancer resistance to platinum chemotherapy.

Gene copy number alterations, tumor cell stemness, and the development of platinum chemotherapy resistance contribute to high-grade serous ovarian cancer (HGSOC) recurrence. Stem phenotypes involving Wnt-β-catenin, aldehyde dehydrogenase activities, intrinsic platinum resistance, and tumorsphere formation are here associated with spontaneous gains in Kras, Myc and FAK (KMF) genes in a new aggressive murine model of ovarian cancer. Adhesion-independent FAK signaling sustained KMF and human tumorsphere proliferation as well as resistance to cisplatin cytotoxicity. Platinum-resistant tumorspheres can acquire a dependence on FAK for growth. Accordingly, increased FAK tyrosine phosphorylation was observed within HGSOC patient tumors surviving neo-adjuvant chemotherapy. Combining a FAK inhibitor with platinum overcame chemoresistance and triggered cell apoptosis. FAK transcriptomic analyses across knockout and reconstituted cells identified 135 targets, elevated in HGSOC, that were regulated by FAK activity and β-catenin including Myc, pluripotency and DNA repair genes. These studies reveal an oncogenic FAK signaling role supporting chemoresistance

Another intermediate mass black hole in a starburst galaxy?: The luminous X-ray source in NGC 3628 reappears

In a 52 ks-long Chandra ACIS-S observation of the nearby starburst galaxy NGC 3628, obtained to study the starburst-driven outflow from this galaxy, we have detected a very luminous (L_X = 1.1e40 erg/s in the 0.3-8.0 keV energy band) point source located at least 20 arcsec (~970 pc) from the nucleus of the galaxy. No radio, optical or near-IR counterpart to this source has been found. This is most probably the reappearance of the strongly-variable X-ray-luminous source discovered by Dahlem et al (1995), which faded by a factor >27 between December 1991 and March 1994 (at which point it had faded below the detection limit in a ROSAT HRI observation). This source is clearly a member of an enigmatic class of X-ray sources that are considerably more luminous than conventional X-ray binaries but less luminous than AGN, and which are not found at the dynamical center of the host galaxy. The Chandra spectrum is best-fit by an absorbed power law model with a photon index of Gamma = 1.8+/-0.2, similar to that seen in Galactic BH binary candidates in their hard state. Bremsstrahlung models or multi-color disk models (the favored spectral model for objects in this class based on ASCA observations) can provide statistically acceptable fits only if the data at energies E > 5 keV is ignored. This is one of the first X-ray spectra of such an object that is unambiguously that of the source alone, free from the spectral contamination by X-ray emission from the rest of the galaxy that affects previous spectral studies of these objects using ASCA.Comment: Accepted for publication in the Ap

Identifying inaccuracies on emergency medicine residency applications

BACKGROUND: Previous trials have showed a 10–30% rate of inaccuracies on applications to individual residency programs. No studies have attempted to corroborate this on a national level. Attempts by residency programs to diminish the frequency of inaccuracies on applications have not been reported. We seek to clarify the national incidence of inaccuracies on applications to emergency medicine residency programs. METHODS: This is a multi-center, single-blinded, randomized, cohort study of all applicants from LCME accredited schools to involved EM residency programs. Applications were randomly selected to investigate claims of AOA election, advanced degrees and publications. Errors were reported to applicants' deans and the NRMP. RESULTS: Nine residencies reviewed 493 applications (28.6% of all applicants who applied to any EM program). 56 applications (11.4%, 95%CI 8.6–14.2%) contained at least one error. Excluding "benign" errors, 9.8% (95% CI 7.2–12.4%), contained at least one error. 41% (95% CI 35.0–47.0%) of all publications contained an error. All AOA membership claims were verified, but 13.7% (95%CI 4.4–23.1%) of claimed advanced degrees were inaccurate. Inter-rater reliability of evaluations was good. Investigators were reluctant to notify applicants' dean's offices and the NRMP. CONCLUSION: This is the largest study to date of accuracy on application for residency and the first such multi-centered trial. High rates of incorrect data were found on applications. This data will serve as a baseline for future years of the project, with emphasis on reporting inaccuracies and warning applicants of the project's goals

Cortactin and phagocytosis in isolated Sertoli cells

BACKGROUND: Cortactin, an actin binding protein, has been associated with Sertoli cell ectoplasmic specializations in vivo, based on its immunolocalization around the heads of elongated spermatids, but not previously identified in isolated Sertoli cells. In an in vitro model of Sertoli cell-spermatid binding, cortactin was identified around debris and dead germ cells. Based on this observation, we hypothesized that this actin binding protein may be associated with a non-junction-related physiological function, such as phagocytosis. The purpose of this study was to identify the presence and distribution of cortactin in isolated rat Sertoli cells active in phagocytic activity following the addition of 0.8 μm latex beads. RESULTS: Sertoli cell monocultures were incubated with or without follicle stimulating hormone (FSH; 0.1 μg/ml) in the presence or absence of cytochalasin D (2 μM), as an actin disrupter. Cortactin was identified by standard immunostaining with anti-cortactin, clone 4F11 (Upstate) after incubation times of 15 min, 2 hr, and 24 hr with or without beads. Cells exposed to no hormone and no beads appeared to have a ubiquitous distribution of cortactin throughout the cytoplasm. In the presence of cytochalasin D, cortactin immunostaining was punctate and distributed in a pattern similar to that reported for actin in cells exposed to cytochalasin D. Sertoli cells not exposed to FSH, but activated with beads, did not show cortactin immunostaining around the phagocytized beads at any of the time periods. FSH exposure did not alter the distribution of cortactin within Sertoli cells, even when phagocytic activity was upregulated by the presence of beads. CONCLUSION: Results of this study suggest cortactin is not associated with peripheralized actin at junctional or phagocytic sites. Further studies are necessary to clarify the role of cortactin in Sertoli cells

Clinical consensus statement: Diagnosis and management of nasal valve compromise

OBJECTIVE: To create a clinical consensus statement to address ambiguities and disparities in the diagnosis and management of nasal valve compromise (NVC). SUBJECTS AND METHODS: An updated systematic review of the literature was conducted. In addition, a Modified Delphi Method was used to refine expert opinion and facilitate a consensus position. RESULTS: After two rounds of surveys and conference calls, 36 items reached consensus, six items reached near consensus, and 10 items reached no consensus. The categories that had the greatest percentage of consensus or near consensus items were as follows: definition, history and physical examination, outcome measures, and management. Conversely, the categories with greater percentage of no consensus items were adjunctive tests and coding. CONCLUSION: The consensus panel agreed that NVC is a distinct clinical entity that is best evaluated with history and physical examination findings. Endoscopy and photography are useful but not routinely indicated, whereas radiographic studies are not useful in evaluating NVC. Other objective nasal outcome measures may not be useful or accepted for NVC. Nasal steroid medication is not useful for treatment of NVC in the absence of rhinitis, and mechanical treatments may be useful in selected patients. Surgical treatment is the primary mode of treatment of NVC, but bill coding remains ambiguous and confusing

The Morphology of Galaxies in the Baryon Oscillation Spectroscopic Survey

We study the morphology of luminous and massive galaxies at 0.3<z<0.7 targeted in the Baryon Oscillation Spectroscopic Survey (BOSS) using publicly available Hubble Space Telescope imaging from COSMOS. Our sample (240 objects) provides a unique opportunity to check the visual morphology of these galaxies which were targeted based solely on stellar population modelling. We find that the majority (74+/-6%) possess an early-type morphology (elliptical or S0), while the remainder have a late-type morphology. This is as expected from the goals of the BOSS target selection which aimed to predominantly select slowly evolving galaxies, for use as cosmological probes, while still obtaining a fair fraction of actively star forming galaxies for galaxy evolution studies. We show that a colour cut of (g-i)>2.35 selects a sub-sample of BOSS galaxies with 90% early-type morphology - more comparable to the earlier Luminous Red Galaxy (LRG) samples of SDSS-I/II. The remaining 10% of galaxies above this cut have a late-type morphology and may be analogous to the "passive spirals" found at lower redshift. We find that 23+/-4% of the early-type galaxies are unresolved multiple systems in the SDSS imaging. We estimate that at least 50% of these are real associations (not projection effects) and may represent a significant "dry merger" fraction. We study the SDSS pipeline sizes of BOSS galaxies which we find to be systematically larger (by 40%) than those measured from HST images, and provide a statistical correction for the difference. These details of the BOSS galaxies will help users of the data fine-tune their selection criteria, dependent on their science applications. For example, the main goal of BOSS is to measure the cosmic distance scale and expansion rate of the Universe to percent-level precision - a point where systematic effects due to the details of target selection may become important.Comment: 18 pages, 11 figures; v2 as accepted by MNRA

Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times $10^{-22}$.Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 200