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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 50 (1990), S. 177-185 
    ISSN: 1432-0649
    Keywords: 52.25.Dg ; 52.25.Nr ; 32.80.Fb
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In a plasma containing hydrogenic ions which is irradiated by appropriate X-ray radiation, gain on the n=3→n=2 (Balmer-α) transition can be generated. Depending on the spectrum of the pump radiation, there are two different ways of obtaining the inversion: direct excitation of the upper laser level by line radiation, or ionization of the hydrogenic ions by broad band radiation with subsequent population of the upper level by recombination. In the first part of this paper, we present numerical calculations which compare the two pumping methods. The gain is evaluated under idealized conditions, i.e., with a pump spectrum containing only radiation useful for generating an inversion and under more realistic conditions, with a pump spectrum containing radiation at other frequencies as well. In the second part of the paper the possibility of obtaining Balmer-α gain in hydrogenic ions under highly transient conditions is investigated, assuming a pump pulse with a duration comparable to the decay time of the lower laser level. Considerable gain is predicted even for a black-body pump spectrum.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7241
    Keywords: nisoldipine ; acute myocardial infarction ; myocardial stunning ; left ventricular function ; radionuclide angiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nisoldipine is a calcium antagonist with potent coronary vasodilating effects in patients with chronic stable angina pectoris. In an initial study we showed that intravenous nisoldipine, given 24–72 hours after uncomplicated myocardial infarction, was a safe and feasible intervention that had beneficial effects on global and regional myocardial function. We subsequently studied the acute effects of nisoldipine in six patients within 24 hours (mean 14±4 hours) after the onset of myocardial infarction. Nisoldipine was administered as a 4.5 µg/kg intravenous bolus over 3 minutes, followed by intravenous infusion of 0.2 µg/kg over 60 minutes. Radionuclide angiography, cardiac output, and intraarterial blood pressure measurements were performed before and during nisoldipine. Left ventricular ejection fraction increased from 48.3±10.3% to 55.3±11.8% (p=0.034) during nisoldipine infusion. Regional wall motion score changed during nisoldipine infusion from 3.3±2.5 to 1.8±2.6 (p=0.027). Cardiac output increased from 5.5±1.0 to 7.3±1.3 1/min (p=0.0001). I eart rate increased from 78±12 to 88±11 min−1 (p=0.004). Mean arterial blood pressure decreased from 92±20 to 79±13 mmI g (p=0.038). The rate-pressure product did not change significantly during nisoldipine infusion. It is concluded that nisoldipine improves global and regional left ventricular function in patients with acute myocardial infarction within the first 24 hours.
    Type of Medium: Electronic Resource
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