Hyperchaos and synchronization in two element nonlinear chimney model.

The two element chimney model with nonlinearity is studied with the aim of modeling the swaying of trees at high wind speeds. We found solutions for various parameters and also the Lyapunov spectrum numerically. The system is chaotic for a wide range of parameters. We also observed hyperchaos in a subregion of this parameter space. We noticed that the hyperchaos was suppressed when the largest Lyapunov exponent crossed a threshold value. Synchronization between the lower and the upper segments was also studied and, for some parameters, phase synchronization is observed. We also observed transition to antisynchronization and also toggling between the two as the parameters are varied.

Anomalies in the motion dynamics of long-flagella mutants of Chlamydomonas reinhardtii.

Chlamydomonas reinhardtii has long been used as a model organism in studies of cell motility and flagellar dynamics. The motility of the well-conserved '9+2' axoneme in its flagella remains a subject of immense curiosity. Using high-speed videography and morphological analyses, we have characterized long-flagella mutants (lf1, lf2-1, lf2-5, lf3-2, and lf4) of C. reinhardtii for biophysical parameters such as swimming velocities, waveforms, beat frequencies, and swimming trajectories. These mutants are aberrant in proteins involved in the regulation of flagellar length and bring about a phenotypic increase in this length. Our results reveal that the flagellar beat frequency and swimming velocity are negatively correlated with the length of the flagella. When compared to the wild-type, any increase in the flagellar length reduces both the swimming velocities (by 26-57%) and beat frequencies (by 8-16%). We demonstrate that with no apparent aberrations/ultrastructural deformities in the mutant axonemes, it is this increased length that has a critical role to play in the motion dynamics of C. reinhardtii cells, and, provided there are no significant changes in their flagellar proteome, any increase in this length compromises the swimming velocity either by reduction of the beat frequency or by an alteration in the waveform of the flagella.