43 research outputs found

    The estimation of black-hole masses in distant radio galaxies

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    We have estimated the masses of the central supermassive black holes of 2442 radio galaxies froma catalog compiled using data from the NED, SDSS, and CATS databases. Mass estimates based on optical photometry and radio data are compared. Relationships between the mass of the central black hole MpbhM_p^{bh} and the redshift zpz_p are constructed for both wavelength ranges. The distribution of the galaxies in these diagrams and systematic effects influencing estimation of the black-hole parameters are discussed. Upperenvelope cubic regression fits are obtained using the maximum estimates of the black-hole masses. The optical and radio upper envelopes show similar behavior, and have very similar peaks in position, zp1.9z_p \simeq 1.9, and amplitude, logMpbh\log M_p^{bh} = 9.4. This is consistent with a model in which the growth of the supermassive black holes is self-regulating, with this redshift corresponding to the epoch when the accretion-flow phase begins to end and the nuclear activity falls off.Comment: 8 pages, 6 figure

    Ketamine, but not Priming, Improves Intubating Conditions During a Propofol-Rocuronium Induction

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    Both ketamine and priming may shorten the onset time of rocuronium. This study investigates the effects of ketamine and priming as components of a propofol induction on intubating conditions and onset of neuromuscular block. This prospective randomized double-blind study was performed in 120 American Society of Anesthesiologists (ASA) I-II patients who were assigned to one of four groups of 30 patients each: control, priming, ketamine, and ketamine-priming. Ketamine 0.5 mg a (TM) kg(-1) or saline was given before priming and induction. Rocuronium 0.06 mg a (TM) kg(-1) or saline was injected 2 min before propofol 2.5 mg a (TM) kg(-1). This was followed by rocuronium 0.6 mg a (TM) kg(-1) or by rocuronium 0.54 mg a (TM) kg(-1) if priming was given. Intubation was performed one minute later. Intubating conditions were graded as excellent, good, or poor. Heart rate, noninvasive blood pressure, and train-of-four (TOF) response were monitored. Intubating conditions were graded excellent in 20% of the control group, 30% of the priming group, 47% of the ketamine group, and 57% of the ketamine-priming group. Analysis using forward stepwise regression indicated that ketamine improved intubating conditions (P = 0.001) but priming did not (P = 0.35). Time to reach a TOF count of zero was shortened by ketamine (P = 0.001) but not by priming (P = 0.94): 216 +/- A 20 s in the control group, 212 +/- A 27 s in the priming group, 162 +/- A 18 s in the ketamine group, and 168 +/- A 22 s in the ketamine-priming group. A low-dose ketamine used with a propofol-rocuronium induction improved intubating conditions and shortened onset time. Priming did not influence intubating conditions or onset time.WoSScopu
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