Diffusion effects of hydrogen bond fluctuations. II. From the short to the long time regime in the translational dynamics of water

1989 ◽  
Vol 91 (2) ◽  
pp. 1191-1203 ◽  
Author(s):  
Davide Bertolini ◽  
Paolo Grigolini ◽  
Alessandro Tani
Keyword(s):  
Hydrogen Bond ◽  
Diffusion Effects ◽  
Time Regime ◽  
Long Time

Diffusion effects of hydrogen bond fluctuations. I. The long time regime of the translational and rotational diffusion of water

1989 ◽  
Vol 91 (2) ◽  
pp. 1179-1190 ◽  
Author(s):  
Davide Bertolini ◽  
Mario Cassettari ◽  
Mauro Ferrario ◽  
Paolo Grigolini ◽  
Giuseppe Salvetti ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Rotational Diffusion ◽  
Diffusion Effects ◽  
Time Regime ◽  
Long Time ◽  
Translational And Rotational Diffusion

Effect of non-uniform passive advection on A+B->C radial reaction-diffusion fronts 

2021 ◽  
Author(s):  
Alessandro Comolli ◽  
Anne De Wit ◽  
Fabian Brau
Keyword(s):  
Molecular Diffusion ◽  
Early Time ◽  
Reaction Diffusion ◽  
Transport Processes ◽  
Calcium Carbonate Precipitation ◽  
Atmospheric Reactions ◽  
Passive Advection ◽  
Reaction Fronts ◽  
Time Regime ◽  
Long Time

<p>The interplay between chemical and transport processes can give rise to complex reaction fronts dynamics, whose understanding is crucial in a wide variety of environmental, hydrological and biological processes, among others. An important class of reactions is A+B->C processes, where A and B are two initially segregated miscible reactants that produce C upon contact. Depending on the nature of the reactants and on the transport processes that they undergo, this class of reaction describes a broad set of phenomena, including combustion, atmospheric reactions, calcium carbonate precipitation and more. Due to the complexity of the coupled chemical-hydrodynamic systems, theoretical studies generally deal with the particular case of reactants undergoing passive advection and molecular diffusion. A restricted number of different geometries have been studied, including uniform rectilinear [1], 2D radial [2] and 3D spherical [3] fronts. By symmetry considerations, these systems are effectively 1D.</p><p>Here, we consider a 3D axis-symmetric confined system in which a reactant A is injected radially into a sea of B and both species are transported by diffusion and passive non-uniform advection. The advective field <em>v<sub>r</sub>(r,z)</em> describes a radial Poiseuille flow. We find that the front dynamics is defined by three distinct temporal regimes, which we characterize analytically and numerically. These are i) an early-time regime where the amount of mixing is small and the dynamics is transport-dominated, ii) a strongly non-linear transient regime and iii) a long-time regime that exhibits Taylor-like dispersion, for which the system dynamics is similar to the 2D radial case.</p><p>                                  <img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.ff5ab530bdff57321640161/sdaolpUECMynit/12UGE&app=m&a=0&c=360a1556c809484116c55812c8c06624&ct=x&pn=gnp.elif&d=1" alt="" width="299" height="299">                                                     <img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.671a6980bdff51231640161/sdaolpUECMynit/12UGE&app=m&a=0&c=c5a857c3fab835057e3af84001a91d15&ct=x&pn=gnp.elif&d=1" alt="" width="302" height="302"></p><p>                                                   Fig. 1: Concentration profile of the product C in the transient (left) and asymptotic (right) regimes.</p><p> </p><p>References:</p><p>[1] L. Gálfi, Z. Rácz, Phys. Rev. A 38, 3151 (1988);</p><p>[2] F. Brau, G. Schuszter, A. De Wit, Phys. Rev. Lett. 118, 134101 (2017);</p><p>[3] A. Comolli, A. De Wit, F. Brau, Phys. Rev. E, 100 (5), 052213 (2019).</p>

THE COMPLETE TREATMENT OF THE TIME EVOLUTION IN THE CASE OF A DISCRETIZED ATOM-FIELD INTERACTION MODEL

2001 ◽  
Vol 15 (21) ◽  
pp. 883-894
Author(s):  
J. SEKE ◽  
A. V. SOLDATOV ◽  
N. N. BOGOLUBOV
Keyword(s):  
State Energy ◽  
Interaction Model ◽  
Time Interval ◽  
Short Time Interval ◽  
Field Interaction ◽  
Markovian Dynamics ◽  
Complete Treatment ◽  
Time Regime ◽  
Long Time ◽  
Short Time

The dynamics of a discretized atom-field interaction model with a physically relevant form factor is analyzed. It is shown that after some short time interval only a small fraction of eigenvalues and eigenstates (belonging to the close vicinity of the excited atomic state energy E = ω0/2) contributes to the nondecay probability amplitudes in the long-time regime, whereas the contribution of all other eigenstates and eigenvalues is negligible. Nevertheless, to describe correctly the non-Markovian dynamics in the short-time regime the contribution of all eigenstates and eigenvalues must be taken into account.

scholarly journals Ultrafast Dynamics of High-Harmonic Generation in Terms of Complex Floquet Spectral Analysis

Symmetry ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 313 ◽  
Author(s):  
Hidemasa Yamane ◽  
Satoshi Tanaka
Keyword(s):  
Spectral Analysis ◽  
Harmonic Generation ◽  
Laser Field ◽  
Quantum Interference ◽  
High Harmonic ◽  
High Harmonic Generation ◽  
Spectral Features ◽  
Quantum Process ◽  
Time Regime ◽  
Long Time

We studied the high-harmonic generation (HHG) of a two-level-system (TLS) driven by an intense monochromatic phase-locked laser based on complex spectral analysis with the Floquet method. In contrast with phenomenological approaches, this analysis deals with the whole process as a coherent quantum process based on microscopic dynamics. We have obtained the time-frequency resolved spectrum of spontaneous HHG single-photon emission from an excited TLS driven by a laser field. Characteristic spectral features of the HHG, such as the plateau and cutoff, are reproduced by the present model. Because the emitted high-harmonic photon is represented as a superposition of different frequencies, the Fano profile appears in the long-time spectrum as a result of the quantum interference of the emitted photon. We reveal that the condition of the quantum interference depends on the initial phase of the driving laser field. We have also clarified that the change in spectral features from the short-time regime to the long-time regime is attributed to the interference between the interference from the Floquet resonance states and the dressed radiation field.

scholarly journals ASYMPTOTIC ENTANGLEMENT OF TWO INDEPENDENT SYSTEMS IN A COMMON BATH

2006 ◽  
Vol 04 (03) ◽  
pp. 395-404 ◽  
Author(s):  
F. BENATTI ◽  
R. FLOREANINI
Keyword(s):  
Quantum Correlations ◽  
Completely Positive ◽  
Time Regime ◽  
Long Time ◽  
Interacting Systems

Two non-interacting systems immersed in a common bath and evolving with a Markovian, completely positive dynamics can become initially entangled via a purely noisy mechanism. Remarkably, for certain phenomenologically relevant environments, the quantum correlations can persist even in the asymptotic long-time regime.

scholarly journals Free radially expanding liquid sheet in air: time- and space-resolved measurement of the thickness field

2015 ◽  
Vol 764 ◽  
pp. 428-444 ◽  
Author(s):  
C. Vernay ◽  
L. Ramos ◽  
C. Ligoure
Keyword(s):  
High Speed ◽  
Liquid Sheet ◽  
Radial Position ◽  
Maximum Diameter ◽  
Time And Space ◽  
Level Measurement ◽  
Time Regime ◽  
Long Time ◽  
Short Time ◽  
Thickness Field

AbstractThe collision of a liquid drop against a small target results in the formation of a thin liquid sheet that extends radially until it reaches a maximum diameter. The subsequent retraction is due to the air–liquid surface tension. We have used a time- and space-resolved technique to measure the thickness field of this class of liquid sheet, based on the grey-level measurement of the image of a dyed liquid sheet recorded using a high-speed camera. This method enables a precise measurement of the thickness in the range $10{-}450~{\rm\mu}\text{m}$, with a temporal resolution equal to that of the camera. We have measured the evolution with time since impact, $t$, and radial position, $r$, of the thickness, $h(r,t)$, for various drop volumes and impact velocities. Two asymptotic regimes for the expansion of the sheet are evidenced. The scalings of the thickness with $t$ and $r$ measured in the two regimes are those that were predicted by Rozhkov et al. (Proc. R. Soc. Lond. A, vol. 460, 2004, pp. 2681–2704) for the short-time regime and Villermaux and Bossa (J. Fluid Mech., vol. 668, 2011, pp. 412–435) for the long-time regime, but never experimentally measured before. Interestingly, our experimental data also provide evidence for the existence of a maximum of the film thickness $h_{max}(r)$ at a radial position $r_{h_{max}}(t)$ corresponding to the cross-over of these two asymptotic regimes. The maximum moves with a constant velocity of the order of the drop impact velocity, as expected theoretically. Thanks to our visualization technique, we also provide evidence of an azimuthal thickness modulation of the liquid sheets.

Assessing (In)security after the Arab Spring: The Case of Yemen

2013 ◽  
Vol 46 (04) ◽  
pp. 721-726 ◽  
Author(s):  
April Longley Alley
Keyword(s):  
Civil Society ◽  
Arab Spring ◽  
Regime Change ◽  
Military Commander ◽  
Time Regime ◽  
Long Time ◽  
High Level ◽  
The Arab Spring ◽  
Large Sections ◽  
Major General

In January 2011, youth and civil society activists, inspired by protests in Tunisia, took to Yemen's streets calling for regime change. As in other Arab Spring countries, conditions were ripe for mobilization as large sections of the population had become increasingly frustrated with corruption, dwindling economic prospects, and a concentration of power and wealth in the hands of the ruling clique. Following Hosni Mubarak's resignation in Egypt, protests mounted across Yemen, and, although President Ali Abdullah Saleh promised reform, it was too little, too late, to satisfy the demonstrators (see ICG 2011a). After proregime gunmen fired on unarmed protesters in Sanaa on March 18, 2011—killing more than 50 demonstrators—a series of high-level defections began, including long-time regime insider and powerful military commander, Major General Ali Mohsen al-Ahmar.

Observation of Laser Speckle Effects in an Elementary Chemical Reaction

2000 ◽  
Vol 651 ◽  
Author(s):  
Eric Monson ◽  
Raoul Kopelman
Keyword(s):  
Reaction Kinetics ◽  
Direct Consequence ◽  
Homogeneous System ◽  
Initial Distribution ◽  
Laser Speckle ◽  
Experimental Demonstration ◽  
Long Wavelength ◽  
Elementary Chemical Reaction ◽  
Time Regime ◽  
Long Time

AbstractAn experimental demonstration is shown for non-classical reaction kinetics in a homogeneous system with an elementary reaction, A+B→C. Sensitivity to the initial distribution of reactants is observed, along with a new reaction-kinetics regime which is a direct consequence of speckles in the laser beam. The long-time regime gives the first experimental demonstration of the asymptotic self-segregation (“Zeldovich”) effect, in spite of the non-random, speckled initial distribution of reactant B. Monte-Carlo simulation results are consistent with the experiments, and spatial analysis of these results correlates the excess of long-wavelength components in the initial reactant distribution with an anomalous slowing of the reaction progress.

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