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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 22 (1982), S. 417-422 
    ISSN: 1432-1041
    Keywords: theophylline ; aminophylline ; obstructive airways disease ; short-term i.v. infusion ; log-normal distribution ; pharmacokinetics ; serum concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Serum theophylline concentrations after intravenous administration of a new short-term infusion (Euphyllin® Kurzzeitinfusion) were measured in 50 out-patients with chronic obstructive airways disease (COAD). An intravenous infusion of theophylline ethylenediamine 480 mg (corresponding to approximately 350 mg anhydrous theophylline) in 50 ml isotonic solution was given in 20 min. Blood samples were taken beforehand and 25 to 30 min and 1, 3 and 6 h after starting the infusion. 86% of the patients had a one-hour serum level in the therapeutic range of 8–20 mg/l, and 2 h later, this was true of 64% of the patients. The short-term infusion was well tolerated, even in cases with unknown high pre-infusion serum levels. Pertinent pharmacokinetic parameters were determined, such as total body clearance, apparent volume of distribution, and half-life of elimination. Geometric mean and 95%-confidence limits, derived from the log-normal distribution of these parameters, were: Cl=0.044 (0.018–0.109) l/h/kg ideal body weight, Vd=0.451 (0.258–0.789) l/kg ideal body weight, and t1/2(el)=7.1 (2.6–19.1) h.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Computing 26 (1981), S. 19-31 
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Gegeben sei ein Pseudo-Zufallszahlen-Generator, der gleichverteilte StichprobenU aus dem Intervall (0, 1) liefert, und eine statistische Verteilung, beschrieben durch ihre VerteilungsfunktionF(x). Dann erzeugt die InversionsmethodeX←F −1(U) Stichproben vonF(x). Ein Verfahren wird entwickelt, das “Guide”-Tafeln erstellt, mit dem Ziel, diese Inversion zu ermöglichen, so daß das Verfahren für beliebigeF(x) effizient wird. Für diskrete Verteilungen sind diese Tafeln klein und leicht zu erstellen, und der entstehende Stichproben-Algorithmus kann mit bekannten allgemeinen Verfahren gut konkurrieren. Stetige Verteilungen erfordern längere Vorbereitungszeiten und mehr Speicherplatz für die Tafeln. Diese werden mit Hilfe gegebener Wahrscheinlichkeitsdichtenf(x) vorbereitet. Die Methode ist anwendbar auf “vernünftige”f(x), einschließlich der normalerweise in der Statistik vorkommenden Fälle. Aufgrund der angeführten Rechenerfahrung mit Poisson-, Normal-, Gamma- und Cauchy-Verteilungen zeigt sich, daß unser allgemeines Verfahren fast so schnell ist, wie die besten bekannten Methoden, die speziell auf diese Verteilungen zugeschnitten wurden.
    Notes: Abstract Given a basic pseudo-random number generator which returns uniformly distributed samplesU from the interval (0, 1) and a statistical distribution as defined by its distribution functionF(x). Then the inversion methodX←F −1 (U) produces samples fromF(x). A procedure is developed which prepares “guide tables” in order to facilitate this inversion so that sampling becomes efficient for arbitraryF(x). For discrete distributions these tables are small and easy to set up, and the resulting sampling algorithm compares well with known general methods. Continuous distributions require longer set-up times and more space for tables. These are prepared using given probability densitiesf(x). The method can cope with “reasonable”f(x) including most cases which are commonly encountered in statistics. The reported computational experience, on Poisson, Normal, Gamma and Cauchy distributions, indicates that our general routine is almost as fast as the best known sampling algorithms which were specially designed for these distributions.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Computing 25 (1980), S. 193-208 
    ISSN: 1436-5057
    Keywords: Random Numbers ; Binomial Distribution ; Poisson Distribution ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Ein exakter Verwerfungsalgorithmus wird konstruiert und ausgetestet. Das Verfahren erfordert durchschnittlich weniger als 3 gleichverteilte Zufallszahlen, solange die Standardabweichung σ der Verteilung mindestens 4 beträgt; diese Anzahl fällt monoton gegen 2,63 für σ→∞. Variable Parameter sind zugelassen; es werden keinerlei Unterprogramme für Stichproben von anderen statistischen Verteilungen benötigt.
    Notes: Abstract An accurate acceptance-rejection algorithm is devised and tested. The procedure requires an average of less than 3 uniform deviates whenever the standard deviation σ of the distribution is at least 4, and this number decreases monotonically to 2.63 as σ→∞. Variable parameters are permitted, and no subroutines for sampling from other statistical distributions are needed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 33 (1984), S. 59-62 
    ISSN: 1432-0630
    Keywords: 7.77 ; 29.25
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A pulsed LINAC is used for pair production in a tantalum target of 2.5 radiation lengths in an energy range from 80 to 260 MeV. Several well-annealed tungsten vanes are placed immediately behind the target and thermalize a small fraction of the fast positrons. The slow positrons are extracted from the target region and magnetically guided over a distance of 17 m to the detector at the end of an S-shaped solenoid. Two Nal detectors with well-known detection efficiency are used to register the 511 keV annihilationγ-rays. To reduce pile-up effects 50 mm of Pb were placed in front of the detectors. At an average electron current of 1 μA we could detect about 107 slow positrons per second. The positron yield is proportional to the electron current, and shows an increase with the electron energy for our target. The positron energy distribution has a FWHM of ∼ 1.8 eV.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical methods of operations research 24 (1980), S. 1-32 
    ISSN: 1432-5217
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Description / Table of Contents: Zusammenfassung Die kapazitierten Transshipmentprobleme bilden die allgemeinste Klasse von Flußproblemen in Netzwerken, die sich mit der Verteilung einer einzigen Ware beschäftigen. Während der letzten zehn Jahre hat sich die Betonung von den primal-dualen Lösungsmethoden zurückverlagert zu den Spezialisierungen des primalen Simplexalgorithmus als der effizienteren Prozedur. Für diesen Übersichtsartikel werden die zahlreichen Variationen in den Datenstrukturen, in den Auswahlregeln und in den Verwirklichungen der einzelnen Schritte aus der entsprechenden Literatur ausgewählt. Die Ausführungen haben als Mittelpunkt einen Algorithmus, der in allen Einzelheiten erklärt wird, wobei den Schwierigkeiten des Basiswechsels besondere Aufmerksamkeit gewidmet wird. Spezielle Lösungsmethoden für Transport- und Zuordnungsprobleme werden mitberücksichtigt.
    Notes: Summary Capacitated transshipment problems constitute the most general class of single commodity network flow problems. During the last ten years the emphasis has shifted away from the primal-dual solution methods back to specializations of the primal simplex algorithm as the more efficient approach. In this survey numerous variations in data structures, selection rules and implementations of individual steps are extracted from the relevant literature. The exposition is centered around one basic algorithm which is explained in complete detail with particular attention to the intricacies of the basis exchange part. Specialized solution methods for transportation and assignment problems are taken into account.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Metrika 31 (1984), S. 227-231 
    ISSN: 1435-926X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary In many casinoes a bet on even money chances is not immediately lost when a zero falls. Instead, the stake is ‘imprisoned’, and the gambler has the options of demanding half his money back or letting the next spins of the wheel decide on the fate of the stake. These options are compared in respect to their winning probabilities by simple recursive methods.
    Type of Medium: Electronic Resource
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