Dynamic versus kinematic symmetry breaking in a two-dimensional model of collective motion

1992 ◽  
Vol 25 (22) ◽  
pp. L1225-L1231 ◽  
Author(s):  
J Cseh
2011 ◽  
Vol 674 ◽  
pp. 163-173 ◽  
Author(s):  
GWYNN J. ELFRING ◽  
ERIC LAUGA

When swimming in close proximity, some microorganisms such as spermatozoa synchronize their flagella. Previous work on swimming sheets showed that such synchronization requires a geometrical asymmetry in the flagellar waveforms. Here we inquire about a physical mechanism responsible for such symmetry breaking in nature. Using a two-dimensional model, we demonstrate that flexible sheets with symmetric internal forcing deform when interacting with each other via a thin fluid layer in such a way as to systematically break the overall waveform symmetry, thereby always evolving to an in-phase conformation where energy dissipation is minimized. This dynamics is shown to be mathematically equivalent to that obtained for prescribed waveforms in viscoelastic fluids, emphasizing the crucial role of elasticity in symmetry breaking and synchronization.


2002 ◽  
Vol 61 (1) ◽  
pp. 34-44 ◽  
Author(s):  
Eric Tafani ◽  
Lionel Souchet

This research uses the counter-attitudinal essay paradigm ( Janis & King, 1954 ) to test the effects of social actions on social representations. Thus, students wrote either a pro- or a counter-attitudinal essay on Higher Education. Three forms of counter-attitudinal essays were manipulated countering respectively a) students’ attitudes towards higher education; b) peripheral beliefs or c) central beliefs associated with this representation object. After writing the essay, students expressed their attitudes towards higher education and evaluated different beliefs associated with it. The structural status of these beliefs was also assessed by a “calling into question” test ( Flament, 1994a ). Results show that behavior challenging either an attitude or peripheral beliefs induces a rationalization process, giving rise to minor modifications of the representational field. These modifications are only on the social evaluative dimension of the social representation. On the other hand, when the behavior challenges central beliefs, the same rationalization process induces a cognitive restructuring of the representational field, i.e., a structural change in the representation. These results and their implications for the experimental study of representational dynamics are discussed with regard to the two-dimensional model of social representations ( Moliner, 1994 ) and rationalization theory ( Beauvois & Joule, 1996 ).


2001 ◽  
Vol 55 (8) ◽  
pp. 14
Author(s):  
A. I. Vyazmitinova ◽  
V. L. Pazynin ◽  
Andrei Olegovich Perov ◽  
Yurii Konstantinovich Sirenko ◽  
H. Akdogan ◽  
...  

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