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  • Springer  (9)
  • Annual Reviews  (1)
  • Nature Publishing Group (NPG)  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 16 (2000), S. 137-145 
    ISSN: 1434-6036
    Keywords: PACS. 82.20.Mj Nonequilibrium kinetics - 05.70.Ln Nonequilibrium and irreversible thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Fast self sustained waves of chemical or phase transformations, observed in several contexts in condensed matter effectively result in “gasless detonation". The phenomenon is modelled by coupling the reaction diffusion equation, describing chemical or phase transformations, and the wave equation, describing elastic perturbations. The coupling considered in this work involves (i) a dependence of the sound velocity on the chemical (phase) field, and (ii) the destruction of the initial chemical equilibrium when the strain exceeds a critical value (strain induced phase transition). Both the case of an initially unstable state (first order kinetics) and metastable state (second order kinetics) are considered. An exhaustive analytic and numerical study of travelling waves reveals the existence of supersonic modes of transformations. The practically important problem of ignition of fast waves by mechanical perturbation is investigated. With the present model, the critical strain necessary to ignite gasless detonation by local perturbations is determined.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Meccanica 29 (1994), S. 343-350 
    ISSN: 1572-9648
    Keywords: Turbulent flows ; Singularities ; Vortex dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Sommario Sono considerate varie questioni correlate con la fisica dei flussi non-viscosi. La nascita di strati di forti vortici è stata ripetutamente osservata nella simulazione delle equazioni tridimensionali, per diverse condizioni iniziali. Nel caso di flussi di Eulero assialsimmetrici, l'origine di questi piani può essere facilmente compresa con l'aiuto di una analogia con i flussi guidati termicamente. Viene inoltre proposto un più generale meccanismo per giustificare questi strati e si passano in rassegna brevemente questioni riguardanti le singolarità. Infine, vengono presentati alcuni risultati preliminari sulla connessione tra i piani formantisi in flussi non viscosi ed i vortici tubolari osservati nei flussi ad alti numeri di Reynolds.
    Notes: Abstract Various questions related to the physics of inviscid flows are reviewed. The emergence of strong vortex sheets has repeatedly been observed in the simulation of the 3-dimensional equations, with a variety of initial conditions. In the case of axisymmetric Euler flows, the origin of these sheets can be easily understood with the help of an analogy with thermally driven flows. A more general mechanism to explain these sheets is proposed. Questions of singularities are briefly reviewed. Lastly, preliminary results on the connection between the sheets forming in inviscid flows, and the vortex tubes observed in high Reynolds number flows are presented.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 10 (1999), S. 379-383 
    ISSN: 1434-6036
    Keywords: PACS. 82.20.Mj Nonequilibrium kinetics - 05.70.Ln Nonequilibrium and irreversible thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Fast self sustained waves (autowaves) associated with chemical or phase transformations are observed in many situations in condensed matter. They are governed neither by diffusion of matter or heat (as in combustion processes) nor by a travelling shock wave (as in gaseous detonation). Instead, they result from a coupling between phase transformation and the stress field, and may be classified as gasless detonation autowaves in solids. We propose a simple model to describe these regimes. The model rests on the classical equations of elastic deformations in a 1-dimensional solid bar, with the extra assumption that the phase (chemical) transformation induces a change of the sound velocity. The transformations are assumed to occur through a chain branched mechanism, which starts when the mechanical stress exceeds a given threshold. Our investigation shows that supersonic autowaves exist in this model. In the absence of diffusion (dissipation factor, losses), a continuum of travelling wave solutions is found. In the presence of diffusion, a steady state supersonic wave solution is found, along with a slower wave controlled by diffusion.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 22 (2001), S. 71-77 
    ISSN: 1434-6036
    Keywords: PACS. 05.70.Ln Nonequilibrium and irreversible thermodynamics – 82.60.Nh Thermodynamics of nucleation – 82.33.Pt Solid state chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Fronts of weakly exothermal chemical reaction may propagate in solids at very low temperatures ( 4K≤T≤77K) thanks to a quite unusual mechanism, involving a feedback between the heat produced by the reaction and the disruption of the solid matrix. In this class of phenomena, the reaction may be induced by mechanical constraints, without a large elevation of temperature. On the basis of a simple phenomenological model, we investigate ignition of a propagating front by initially (i) disrupting a localized zone of the solid matrix, or by (ii) introducing a temperature jump, leading to a thermal shock with strong temperature gradients. In particular, we show that reaction can be initiated by disrupting only a very small fraction of the sample. Applications to the problem of initiation of solid explosives by friction or shocks is briefly discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 37 (1984), S. 39-49 
    ISSN: 1572-9613
    Keywords: Intrinsic Stochasticity ; turbulent fluctuations ; energy transfer ; Lyapunov exponents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We study a simple model equation describing a system with an infinity of degrees of freedom which displays an intrinsically chaotic behavior. Some concepts of fully developed turbulence are discussed in relation to this model. We also develop an approach based on Lyapunov exponent measurements. Numerical results on the distribution of Lyapunov numbers and the power spectrum of the associated Lyapunov vectors are presented and briefly discussed.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2011-07-15
    Description: Controlling the complex spatio-temporal dynamics underlying life-threatening cardiac arrhythmias such as fibrillation is extremely difficult, because of the nonlinear interaction of excitation waves in a heterogeneous anatomical substrate. In the absence of a better strategy, strong, globally resetting electrical shocks remain the only reliable treatment for cardiac fibrillation. Here we establish the relationship between the response of the tissue to an electric field and the spatial distribution of heterogeneities in the scale-free coronary vascular structure. We show that in response to a pulsed electric field, E, these heterogeneities serve as nucleation sites for the generation of intramural electrical waves with a source density rho(E) and a characteristic time, tau, for tissue depolarization that obeys the power law tau proportional, variant E(alpha). These intramural wave sources permit targeting of electrical turbulence near the cores of the vortices of electrical activity that drive complex fibrillatory dynamics. We show in vitro that simultaneous and direct access to multiple vortex cores results in rapid synchronization of cardiac tissue and therefore, efficient termination of fibrillation. Using this control strategy, we demonstrate low-energy termination of fibrillation in vivo. Our results give new insights into the mechanisms and dynamics underlying the control of spatio-temporal chaos in heterogeneous excitable media and provide new research perspectives towards alternative, life-saving low-energy defibrillation techniques.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153959/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153959/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Luther, Stefan -- Fenton, Flavio H -- Kornreich, Bruce G -- Squires, Amgad -- Bittihn, Philip -- Hornung, Daniel -- Zabel, Markus -- Flanders, James -- Gladuli, Andrea -- Campoy, Luis -- Cherry, Elizabeth M -- Luther, Gisa -- Hasenfuss, Gerd -- Krinsky, Valentin I -- Pumir, Alain -- Gilmour, Robert F Jr -- Bodenschatz, Eberhard -- HL073644/HL/NHLBI NIH HHS/ -- HL075515/HL/NHLBI NIH HHS/ -- HL075515-S04/HL/NHLBI NIH HHS/ -- P41-EB001977/EB/NIBIB NIH HHS/ -- R01 HL073644/HL/NHLBI NIH HHS/ -- R01 HL073644-05/HL/NHLBI NIH HHS/ -- R01 HL075515/HL/NHLBI NIH HHS/ -- R01 HL075515-04/HL/NHLBI NIH HHS/ -- R01 HL075515-04S2/HL/NHLBI NIH HHS/ -- England -- Nature. 2011 Jul 13;475(7355):235-9. doi: 10.1038/nature10216.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, D-37077 Gottingen, Germany. stefan.luther@ds.mpg.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21753855" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atrial Fibrillation/*physiopathology ; Contrast Media ; Coronary Vessels/anatomy & histology ; Dogs ; Electric Countershock/instrumentation/*methods ; Electrocardiography ; Heart/anatomy & histology/*physiology/*physiopathology ; Ventricular Fibrillation/*physiopathology ; X-Ray Microtomography
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 1999-08-01
    Print ISSN: 1434-6028
    Electronic ISSN: 1434-6036
    Topics: Physics
    Published by Springer
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  • 8
    Publication Date: 2001-07-01
    Print ISSN: 1434-6028
    Electronic ISSN: 1434-6036
    Topics: Physics
    Published by Springer
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  • 9
    Publication Date: 2000-06-01
    Print ISSN: 1434-6028
    Electronic ISSN: 1434-6036
    Topics: Physics
    Published by Springer
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  • 10
    Publication Date: 2007-11-01
    Print ISSN: 1434-6028
    Electronic ISSN: 1434-6036
    Topics: Physics
    Published by Springer
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