Plasma levels of immunoreactive atrial natriuretic factor increase during supraventricular tachycardia

A significant diuretic and natriuretic response occurs during paroxysmal supraventricular tachycardia (SVT). Although the diuresis may be secondary to suppression of vasopressin secretion, the etiology of the natriuresis remains unexplained. To determine if atrial natriuretic factor (ANF) could contribute to the polyuric response during SVT, 10 patients were studied: five during spontaneous SVT and five during simulated SVT produced by rapid simultaneous atrial and ventricular pacing. Plasma immunoreactive ANF (IR-ANF) levels measured by radioimmunoassay were obtained at baseline (before and/or 24 to 48 hours after SVT) and after at least 15 minutes of SVT in all patients. During spontaneous and simulated SVT, IR-ANF was significantly elevated (mean +/- SE; 275 +/- 68 pmol/L) compared to baseline (28 +/- 7 pmol/L; P = 0.0036). Similar increases in IR-ANF were noted during both simulated and spontaneous SVT. To determine if this IR-ANF release was related to the increase in heart rate or the rise in right atrial pressure during SVT, IR-ANF levels were also measured in five patients with sinus tachycardia and in six patients with congestive heart failure, IR-ANF was significantly related to right atrial pressure (r = 0.93; P = 0.0009) but not to heart rate (r = 0.46). Thus, IR-ANF is elevated during SVT and may contribute to the natriuretic response. The stimulus to IR-ANF secretion during SVT appears to be related to the rise in right atrial pressure rather than to the increase in heart rate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26001/1/0000067.pd

Another look at the BL Lacertae flux and spectral variability

The GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT) monitored BL Lacertae in 2008-2009 at radio, near-IR, and optical frequencies. During this period, high-energy observations were performed by XMM-Newton, Swift, and Fermi. We analyse these data with particular attention to the calibration of Swift UV data, and apply a helical jet model to interpret the source broad-band variability. The GASP-WEBT observations show an optical flare in 2008 February-March, and oscillations of several tenths of mag on a few-day time scale afterwards. The radio flux is only mildly variable. The UV data from both XMM-Newton and Swift seem to confirm a UV excess that is likely caused by thermal emission from the accretion disc. The X-ray data from XMM-Newton indicate a strongly concave spectrum, as well as moderate flux variability on an hour time scale. The Swift X-ray data reveal fast (interday) flux changes, not correlated with those observed at lower energies. We compare the spectral energy distribution (SED) corresponding to the 2008 low-brightness state, which was characterised by a synchrotron dominance, to the 1997 outburst state, where the inverse-Compton emission was prevailing. A fit with an inhomogeneous helical jet model suggests that two synchrotron components are at work with their self inverse-Compton emission. Most likely, they represent the radiation from two distinct emitting regions in the jet. We show that the difference between the source SEDs in 2008 and 1997 can be explained in terms of pure geometrical variations. The outburst state occurred when the jet-emitting regions were better aligned with the line of sight, producing an increase of the Doppler beaming factor. Our analysis demonstrates that the jet geometry can play an extremely important role in the BL Lacertae flux and spectral variability.Comment: 12 pages, 10 figures, accepted for publication in A&

Development of a new model for rotator cuff pathology: the rabbit subscapularis muscle

Background and purpose The New Zealand white rabbit subscapularis tendon passes under a bony arch to insert on the lesser tubercle of the humerus in a manner analogous to the supraspinatus tendon in humans. We assessed whether this unique anatomy may provide a new animal model of the shoulder to improve our understanding of rotator cuff pathology

The first Fermi multifrequency campaign on BL Lacertae: characterizing the low-activity state of the eponymous blazar

We report on observations of BL Lacertae during the first 18 months of Fermi-LAT science operations and present results from a 48-day multifrequency coordinated campaign from 2008 August 19 to 2008 October 7. The radio to gamma-ray behavior of BL Lac is unveiled during a low activity state thanks to the coordinated observations of radio-band (Metsahovi and VLBA), near-IR/optical (Tuorla, Steward, OAGH and MDM) and X-ray (RXTE and Swift) observatories. No variability was resolved in gamma-rays during the campaign, and the brightness level was 15 times lower than the level of the 1997 EGRET outburst. Moderate and uncorrelated variability has been detected in UV and X-rays. The X-ray spectrum is found to be concave indicating the transition region between the low and high energy component of the spectral energy distribution (SED). VLBA observation detected a synchrotron spectrum self-absorption turnover in the innermost part of the radio jet appearing to be elongated and inhomogeneous, and constrained the average magnetic field there to be less than 3 G. Over the following months BL Lac appeared variable in gamma-rays, showing flares (in 2009 April and 2010 January). There is no evidence for correlation of the gamma-rays with the optical flux monitored from the ground in 18 months. The SED may be described by a single zone or two zone synchrotron self-Compton (SSC) model, but a hybrid SSC plus external radiation Compton (ERC) model seems preferred based on the observed variability and the fact that it provides a fit closest to equipartition.Comment: 14 pages, apj-style emulated, 10 figures. In press by The Astrophysical Journa

A tidal disruption event coincident with a high-energy neutrino

Cosmic neutrinos provide a unique window into the otherwise hidden mechanism of particle acceleration in astrophysical objects. The IceCube Collaboration recently reported the likely association of one high-energy neutrino with a flare from the relativistic jet of an active galaxy pointed towards the Earth. However a combined analysis of many similar active galaxies revealed no excess from the broader population, leaving the vast majority of the cosmic neutrino flux unexplained. Here we present the likely association of a radio-emitting tidal disruption event, AT2019dsg, with a second high-energy neutrino. AT2019dsg was identified as part of our systematic search for optical counterparts to high-energy neutrinos with the Zwicky Transient Facility. The probability of finding any coincident radio-emitting tidal disruption event by chance is 0.5%, while the probability of finding one as bright in bolometric energy flux as AT2019dsg is 0.2%. Our electromagnetic observations can be explained through a multizone model, with radio analysis revealing a central engine, embedded in a UV photosphere, that powers an extended synchrotron-emitting outflow. This provides an ideal site for petaelectronvolt neutrino production. Assuming that the association is genuine, our observations suggest that tidal disruption events with mildly relativistic outflows contribute to the cosmic neutrino flux

Multi-wavelength observations of blazar AO 0235+164 in the 2008-2009 flaring state

The blazar AO 0235+164 (z = 0.94) has been one of the most active objects observed by Fermi Large Area Telescope (LAT) since its launch in Summer 2008. In addition to the continuous coverage by Fermi, contemporaneous observations were carried out from the radio to γ-ray bands between 2008 September and 2009 February. In this paper, we summarize the rich multi-wavelength data collected during the campaign (including F-GAMMA, GASP-WEBT, Kanata, OVRO, RXTE, SMARTS, Swift, and other instruments), examine the cross-correlation between the light curves measured in the different energy bands, and interpret the resulting spectral energy distributions in the context of well-known blazar emission models. We find that the γ-ray activity is well correlated with a series of near-IR/optical flares, accompanied by an increase in the optical polarization degree. On the other hand, the X-ray light curve shows a distinct 20 day high state of unusually soft spectrum, which does not match the extrapolation of the optical/UV synchrotron spectrum. We tentatively interpret this feature as the bulk Compton emission by cold electrons contained in the jet, which requires an accretion disk corona with an effective covering factor of 19% at a distance of 100 R g. We model the broadband spectra with a leptonic model with external radiation dominated by the infrared emission from the dusty torus. © 2012. The American Astronomical Society. All rights reserved

U.S. Equity Markets and Environmental Policy. The Case of Electric Utility Investor Behavior During the Passage of the Clean Air Act Amendments of 1990

We examine electric utilityinvestor reaction surrounding twenty-twomilestones associated with the passage of theClean Air Act Amendments of 1990. Resultssuggest that investors did not react sharply tothe passage of the Amendments. To the extentthat statistically significant effects wereobserved, we interpret the results as moreindicative of investor concern over resolutionof uncertainty surrounding the politicalprocess and resulting provisions than ofconcern over the expected costs of compliancefollowing passage of the Amendments. Weobserved little, if any, difference betweenutilities subject to Phase I restrictions andthose not subject to Phase I. Finally, changesin monthly excess returns appear to haveresulted from changes in U.S. interest ratesand investor concern over power industryderegulation. We view our results as importantbecause any wealth effects due to environmentalregulations represent a real economic costassociated with their implementation. In thissense, we view the results as “good news” forU.S. environmental policy makers. Copyright Kluwer Academic Publishers 2002acid rain, capital markets, Clean Air Act Amendments, electric utility, event study, valuation,