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  • 1975-1979  (4)
  • General Chemistry  (2)
  • Series Elastic  (1)
  • branching ratio  (1)
  • Internode length
  • 1
    Electronic Resource
    Electronic Resource
    Series elasticity in the intact heart (1975)
    Springer
    Pflügers Archiv 357 (1975), S. 225-236 
    Details
    ISSN: 1432-2013
    Keywords: Series Elastic ; Muscle Models ; Force Velocity ; Stress-Strain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Several recent studies have shown that the contractile state of the intact heart may be described by the instantaneous relationships between contractile element velocity, length and stress. However, there is little direct evidence that the intact heart can be described by a model containing at least a contractile element and a series elastic component (SEC). In isolated muscle the series elastic component can be analyzed by determining the length changes following quick releases to known loads during contraction. The characteristics of the effective SEC of the intact left ventricle (LV) were determined by a quick release method in 8 dogs in which the left ventricle contracted isovolumically against a balloon inserted via the mitral annulus. During active contraction, sequential withdrawals of 0.5 to 7.0 ml of fluid were performed rapidly (5–18 msec) by an electrically-timed, spring-loaded syringe. From these releases the calculated maximum extension of the SEC averaged 4.03±0.27% of LV circumference at LV pressures averaging 79/6 mmHg (systolic/end-diastolic; range 66–107/0–15 mmHg.) The reductions of the left ventricular midwall circumference were plotted against the corresponding changes in mean wall stress. The load extension curve determined in this manner was unchanged by varying the time of release and by norepinephrine infusion. These data support a model for the intact LV that contains an undamped SEC, the characteristics of which resemble those of isolated cardiac muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585977
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Analytic results for asymmetric Random Walk with exponential transition probabilities (1978)
    Springer
    Journal of statistical physics 19 (1978), S. 525-541 
    Details
    ISSN: 1572-9613
    Keywords: Random walks ; stochastic processes ; exponential models ; mean first passage time ; branching ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present here exact analytic results for a random walk on a one-dimensional lattice with asymmetric, exponentially distributed jump probabilities. We derive the generating functions of such a walk for a perfect lattice and for a lattice with absorbing boundaries. We obtain solutions for some interesting moment properties, such as mean first passage time, drift velocity, dispersion, and branching ratio for absorption. The symmetric exponential walk is solved as a special case. The scaling of the mean first passage time with the size of the system for the exponentially distributed walk is determined by the symmetry and is independent of the range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01011697
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Eine Basis für die Orbitalsymmetrieregeln (1979)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 91 (1979), S. 363-379 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Der Einfluß der Molekülsymmetrie auf die Reaktionsgeschwindigkeit wird mit einem Verfahren untersucht, das chemische Reaktionen als elektronische Übergänge zwischen Edukt- und Produktzuständen betrachtet, wobei diese Zustände durch quasiadiabatische Potentialflächen beschrieben werden. Für diese Übergänge werden unter Verwendung des molekularen Hamilton-Operators Auswahlregeln hergeleitet. Der vollständige Hamilton-Operator weist keine brauchbare Symmetrie auf; die Vernachlässigung von Nicht-Born-Oppenheimer-Termen, von Spin-Bahn-Kopplungstermen und anderen Drehimpulskopplungstermen ergibt einen approximierten Hamilton-Operator und führt zu Auswahlregeln, welche die Basis der Woodward-Hoffmann-Regeln bilden. Dieser Ansatz bietet eine Alternative zu den adiabatischen Potentialflächen, den Reaktionskoordinaten und der Theorie des Übergangszustandes, die bei der Diskussion der Woodward-Hoffmann-Regeln üblicherweise zugrunde gelegt werden. Darüber hinaus lassen sich mit diesem Ansatz Verletzungen der Symmetrieregeln besonders gut diskutieren und konzertierte von nichtkonzentrierten Reaktionen unterscheiden.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19790910504
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A Basis for Orbital Symmetry Rules (1979)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 18 (1979), S. 377-392 
    Details
    ISSN: 0570-0833
    Keywords: Orbital symmetry ; Woodward-Hoffmann rules ; Kinetics ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of molecular symmetry on reaction rates is examined with an approach in which reactions are viewed as electronic transitions between states of reacants and products (described, in turn by quasiadiabatic potential surface). The moleculer Hamiltonian is used to derive selection rules for these transitions. The complete Hamilatonian has no useful symmetery. Neglect of non-Born-Oppenheimer and spin-orbit terms (and of other angular momentum coupling terms) leads to an apporixmate Hamiltonian and to selection rules which from the basis of the Woodward-Hoffmann rules. This apporch provides an alternative to the adiabatic potantial surfaces, reaction coordinates, and transition state theory used in more familiar discussions of the Woodward-Hoffmann rules. Further, it provides a particulary clear method for discussing violations of these symmetry rules, and for differentiating concerted and nonconcerted reactions.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/anie.197903771
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    Paper (German National Licenses)
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