Viscous accretion discs around rotating black holes

The stationary hydrodynamic equations for transonic viscous accretion discs in Kerr geometry are derived. The consistent formulation is given for the viscous angular momentum transport and the boundary conditions on the horizon of a central black hole. An expression for the thickness of the disc is obtained from the vertical Euler equation for general accretion flows with vanishing vertical velocity. Different solution topologies are identified, characterized by a sonic transition close to or far from the marginally stable orbit. A numerical method is presented that allows to integrate the structure equations of transonic accretion flows. Global polytropic solutions for the disc structure are calculated, covering each topology and a wide range of physical conditions. These solutions generally possess a sub-Keplerian angular momentum distribution and have maximum temperatures in the range $10^{11}-10^{12}$ K. Accretion discs around rotating black holes are hotter and deposit less angular momentum on the central object than accretion discs around Schwarzschild black holes.Comment: 15 pages LateX, requires mn.sty, accepted for publication in the MNRAS, figures available at http://www.lsw.uni-heidelberg.de/~jpeitz/PV

3+1 formulation of non-ideal hydrodynamics

The equations governing dissipative relativistic hydrodynamics are formulated within the 3+1 approach for arbitrary spacetimes. Dissipation is accounted for by applying the theory of extended causal thermodynamics (Israel-Stewart theory). This description eliminates the causality violating infinite signal speeds present in the conventional Navier-Stokes equation. As an example we treat the astrophysically relevant case of stationary and axisymmetric spacetimes, including the Kerr metric. The equations take a simpler form whenever the inertia due to the dissipative contributions can be neglected.Comment: 24 pages, LateX, uses mn.sty and AMS fonts, no figures, accepted for publication in the MNRAS, also available via http://www.lsw.uni-heidelberg.de/~jpeitz/Personal.htm

Fast loose rivet detection by using scanning laser doppler vibrometry

Until today, the manual inspection of riveted lab joints and detection of loose or damaged rivets is a time-consuming and costly task in the regular maintenance of civil aircraft. Many studies investigate the crack propagation in rivet holes or the influence of manufacturing parameters to the durability of riveted lab joints. However, no automated and digital in-situ quality assessment for loose and damaged rivets is explored so far. This work presents a study on a real aircraft fuselage panel in which Scanning Laser Doppler Vibrometer measurements enable the detection and distinction of loose, damaged and intact countersunk rivets. On the one hand, a chirp sine excitation allows the detection of loose rivets by a coherence analysis of the excitation signal and the measured vibration. On the other hand, damaged and intact rivets appear in the vibration analysis as so-called local defect resonances at low and high frequencies respectively. The presented work potentially leads to a digital, automated and full-field inspection method suitable for the application in an industrial environment like the regular aircraft maintenance.status: publishe

Interactions of recombinant human histamine H₁R, H₂R, H₃R, and H₄R receptors with 34 antidepressants and antipsychotics.

Antidepressants and antipsychotics affect multiple molecular targets. Consequently, these drugs exhibit not only unique profiles of therapeutic effects but also several undesired effects. Histamine receptors (H₁R, H₂R, H₃R, and H₄R) belong to the large family of G protein-coupled receptors and are very important drug targets. All four H(x)R subtypes are expressed in the CNS. Interactions of lipophilic, blood-brain barrier-penetrating drugs with H(x)Rs could contribute to therapeutic and unwanted effects. Therefore, we investigated potencies H(x)R as well as potencies and (inverse) agonistic efficacies of 34 antidepressants and antipsychotics at HxRs in functional assays. We expressed human H(x)Rs in Sf9 insect cells and conducted radioligand competition binding experiments and functional steady-state GTPase assays. Ligand affinities and potencies were compared with literature data and related to therapeutic reference ranges. Almost all antidepressants and antipsychotics displayed high binding affinities to H₁R and behaved as antagonists. The atypical antidepressant trimipramine behaved as a high-affinity/high-potency H₂R antagonist (pK(i), 7.39; pK(B), 7.36; pA₂, 7.55). Docking to an H₂R model suggested a probable binding mode. The affinity of antidepressants and antipsychotics for H₃R was low. The atypical antipsychotic clozapine, known to induce agranulocytosis, exhibited partial H₄R agonism for which docking experiments provided a molecular basis. Clozapine also exhibited H₂R antagonism. We observed dissociations between pK(i) and pK (B) values as well as between pK(i) and pIC₅₀ values for H(x)Rs. Antidepressants and antipsychotics interact differentially with H(x)Rs. The concept of functional selectivity (also referred to as ligand-specific receptor conformations or biased signaling) explains dissociations between pK(i) and pK(B) values as well as differences between pK(i) and pIC₅₀ values. The H₁R antagonism of numerous antidepressants and antipsychotics is very pronounced. The H₂R antagonism of trimipramine and partial H₄R agonism of clozapine may be clinically relevant. We also discuss the possible role of the H₂R antagonism of clozapine for neutropenia/agranulocytosis induced by this compound. Finally, we discuss the methodological, conceptual, and clinical limitations of our study

TweezPal – optical tweezers analysis and calibration software

Abstract Optical tweezers, a powerful tool for optical trapping, micromanipulation and force transduction, have in recent years become a standard technique commonly used in many research laboratories and university courses. Knowledge about the optical force acting on a trapped object can be gained only after a calibration procedure which has to be performed (by an expert) for each type of trapped objects. In this paper we present TweezPal, a user-friendly, standalone Windows software tool for optical tweezers analysis and calibration. Using TweezPal, the procedure can be performed in a matter of minutes even by non-expert users. The calibration is based on the Brownian motion of a particle trapped in a stationary optical trap, which is being monitored using video or photodiode detection. The particle trajectory is imported into the software which instantly calculates position histogram, trapping potential, stiffness and anisotropy. PROGRAM SUMMARY Manuscript title: TweezPal -Optical tweezers analysis and calibration softwar

Cardioverter defibrillator implantation without induction of ventricular fibrillation: a single-blind, non-inferiority, randomised controlled trial (SIMPLE).

International audienceDefibrillation testing by induction and termination of ventricular fibrillation is widely done at the time of implantation of implantable cardioverter defibrillators (ICDs). We aimed to compare the efficacy and safety of ICD implantation without defibrillation testing versus the standard of ICD implantation with defibrillation testing. In this single-blind, randomised, multicentre, non-inferiority trial (Shockless IMPLant Evaluation [SIMPLE]), we recruited patients aged older than 18 years receiving their first ICD for standard indications at 85 hospitals in 18 countries worldwide. Exclusion criteria included pregnancy, awaiting transplantation, particpation in another randomised trial, unavailability for follow-up, or if it was expected that the ICD would have to be implanted on the right-hand side of the chest. Patients undergoing initial implantation of a Boston Scientific ICD were randomly assigned (1:1) using a computer-generated sequence to have either defibrillation testing (testing group) or not (no-testing group). We used random block sizes to conceal treatment allocation from the patients, and randomisation was stratified by clinical centre. Our primary efficacy analysis tested the intention-to-treat population for non-inferiority of no-testing versus testing by use of a composite outcome of arrhythmic death or failed appropriate shock (ie, a shock that did not terminate a spontaneous episode of ventricular tachycardia or fibrillation). The non-inferiority margin was a hazard ratio (HR) of 1·5 calculated from a proportional hazards model with no-testing versus testing as the only covariate; if the upper bound of the 95% CI was less than 1·5, we concluded that ICD insertion without testing was non-inferior to ICD with testing. We examined safety with two, 30 day, adverse event outcome clusters. The trial is registered with ClinicalTrials.gov, number NCT00800384. Between Jan 13, 2009, and April 4, 2011, of 2500 eligible patients, 1253 were randomly assigned to defibrillation testing and 1247 to no-testing, and followed up for a mean of 3·1 years (SD 1·0). The primary outcome of arrhythmic death or failed appropriate shock occurred in fewer patients (90 [7% per year]) in the no-testing group than patients who did receive it (104 [8% per year]; HR 0·86, 95% CI 0·65-1·14; pnon-inferiority <0·0001). The first safety composite outcome occurred in 69 (5·6%) of 1236 patients with no-testing and in 81 (6·5%) of 1242 patients with defibrillation testing, p=0·33. The second, pre-specified safety composite outcome, which included only events most likely to be directly caused by testing, occurred in 3·2% of patients with no-testing and in 4·5% with defibrillation testing, p=0·08. Heart failure needing intravenous treatment with inotropes or diuretics was the most common adverse event (in 20 [2%] of 1236 patients in the no-testing group vs 28 [2%] of 1242 patients in the testing group, p=0·25). Routine defibrillation testing at the time of ICD implantation is generally well tolerated, but does not improve shock efficacy or reduce arrhythmic death. Boston Scientific and the Heart and Stroke Foundation (Ontario Provincial office)