Excitation of internal seiches by periodic forcing

Author(s):  
E. Bäuerle
Author(s):  
Giovanni Formica ◽  
Nicoló Vaiana ◽  
Luciano Rosati ◽  
Walter Lacarbonara

2011 ◽  
Vol 44 (9) ◽  
pp. 728-738 ◽  
Author(s):  
Guoyong Yuan ◽  
Lin Xu ◽  
Aiguo Xu ◽  
Guangrui Wang ◽  
Shiping Yang

The first part of this paper is taken up with an historical survey of the relatively few observations, some detailed and some less so, of internal seiches (internal standing waves) in lakes. After a description of the thermo-electric thermometer employed, there follow details and illustrations of the evidence, from temperature observations, for such internal waves in the northern basin of Windermere. Two main phases could be distinguished: (i) motion under wind stress leading to quasi-steady states with some or all of the isotherms tilted; (ii) internal seiche motion which developed after the wind had dropped. These observations confirm the findings of Wedderburn and his collaborators on the Scottish Lochs (1907-15). The results from Windermere are presented, not because any such confirmation is necessary, but in order to secure belated recognition of the fact that Wedderburn’s ‘ temperature seiche ’ is not an isolated phenomenon, but is an everyday feature of movement in stratified lakes subject to wind action. As this movement is an important and largely unrecognized factor in lake environment, this paper is addressed mainly to limnologists. In its latter part, results of theoretical analyses of a detailed series of observations are presented in non-mathematical form. The applicability of a theory of oscillations in a basin with three layers of differing density (set out in an appendix by M. S. Longuet-Higgins) is tested by comparing theoretical and observed deflexions of selected isotherms from their equilibrium levels, resulting from internal waves after a gale. This theory also enables horizontal components of velocity and displacement to be calculated for each layer. Complicating factors in natural lakes are enumerated, and the influence of internal waves on lake biology and sedimentation is discussed.


2010 ◽  
Vol 59 (1) ◽  
pp. 43-51 ◽  
Author(s):  
M. G. Clerc ◽  
F. Haudin ◽  
S. Residori ◽  
U. Bortolozzo ◽  
R. G. Rojas

1994 ◽  
Vol 66 (6) ◽  
pp. 1844-1852 ◽  
Author(s):  
D. Petracchi ◽  
M. Pellegrini ◽  
M. Pellegrino ◽  
M. Barbi ◽  
F. Moss
Keyword(s):  

2001 ◽  
Vol 85 (4) ◽  
pp. 1623-1638 ◽  
Author(s):  
Attila Szűcs ◽  
Robert C. Elson ◽  
Michail I. Rabinovich ◽  
Henry D. I. Abarbanel ◽  
Allen I. Selverston

Periodic current forcing was used to investigate the intrinsic dynamics of a small group of electrically coupled neurons in the pyloric central pattern generator (CPG) of the lobster. This group contains three neurons, namely the two pyloric dilator (PD) motoneurons and the anterior burster (AB) interneuron. Intracellular current injection, using sinusoidal waveforms of varying amplitude and frequency, was applied in three configurations of the pacemaker neurons: 1) the complete pacemaker group, 2) the two PDs without the AB, and 3) the AB neuron isolated from the PDs. Depending on the frequency and amplitude of the injected current, the intact pacemaker group exhibited a wide variety of nonlinear behaviors, including synchronization to the forcing, quasiperiodicity, and complex dynamics. In contrast, a single, broad 1:1 entrainment zone characterized the response of the PD neurons when isolated from the main pacemaker neuron AB. The isolated AB responded to periodic forcing in a manner similar to the complete pacemaker group, but with wider zones of synchronization. We have built an analog electronic circuit as an implementation of a modified Hindmarsh-Rose model for simulating the membrane potential activity of pyloric neurons. We subjected this electronic model neuron to the same periodic forcing as used in the biological experiments. This four-dimensional electronic model neuron reproduced the autonomous oscillatory firing patterns of biological pyloric pacemaker neurons, and it expressed the same stationary nonlinear responses to periodic forcing as its biological counterparts. This adds to our confidence in the model. These results strongly support the idea that the intact pyloric pacemaker group acts as a uniform low-dimensional deterministic nonlinear oscillator, and the regular pyloric oscillation is the outcome of cooperative behavior of strongly coupled neurons, having different dynamical and biophysical properties when isolated.


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