Publications

@article{Saxena2012,
title = {Amplitude death: The emergence of stationarity in coupled nonlinear systems},
author = {Garima Saxena and Awadhesh Prasad and Ram Ramaswamy},
url = {https://ramramaswamy.org/papers/RC43.pdf},
doi = {10.1016/j.physrep.2012.09.003},
issn = {03701573},
year = {2012},
date = {2012-01-01},
journal = {Physics Reports},
volume = {521},
number = {5},
pages = {205–228},
abstract = {When nonlinear dynamical systems are coupled, depending on the intrinsic dynamics and the manner in which the coupling is organized, a host of novel phenomena can arise. In this context, an important emergent phenomenon is the complete suppression of oscillations, formally termed amplitude death (AD). Oscillations of the entire system cease as a consequence of the interaction, leading to stationary behavior. The fixed points which the coupling stabilizes can be the otherwise unstable fixed points of the uncoupled system or can correspond to novel stationary points. Such behavior is of relevance in areas ranging from laser physics to the dynamics of biological systems. In this review we discuss the characteristics of the different coupling strategies and scenarios that lead to AD in a variety of different situations, and draw attention to several open issues and challenging problems for further study. textcopyright 2012 Elsevier B.V.},
keywords = {Amplitude quenching, Bifurcation, Control, Fixed-point solution, Interaction, Network, Synchronization},
pubstate = {published},
tppubtype = {article}
}

@article{Tiwari1996,
title = {Adaptive control in a resource management model},
author = {Shrish Tiwari and Ramakrishna Ramaswamy and J.Subba Rao},
url = {https://ramramaswamy.org/papers/056.pdf},
doi = {10.1016/0304-3800(94)00143-x},
issn = {03043800},
year = {1996},
date = {1996-01-01},
journal = {Ecological Modelling},
volume = {84},
number = {1-3},
pages = {53–62},
abstract = {We cast a model of biological resource management as a problem of adaptive control in a nonlinear dynamical system. Optimisation of harvest, while ensuring that the resource population persists, is achieved through a simple algorithmic procedure which is remarkably robust under a variety of perturbations. textcopyright 1996 Elsevier Science B.V. All rights reserved.},
keywords = {Control, Optimization, Resource Management},
pubstate = {published},
tppubtype = {article}
}

@article{Sinha1989,
title = {Spectral rigidity in atomic uranium},
author = {S Sinha and Ramakrishna Ramaswamy},
url = {https://ramramaswamy.org/papers/038.pdf},
doi = {10.1088/0953-4075/22/19/012},
issn = {09534075},
year = {1989},
date = {1989-01-01},
journal = {Journal of Physics B: Atomic, Molecular and Optical Physics},
volume = {22},
number = {19},
pages = {2985–2990},
abstract = {The authors study the level statistics of parity-selected electronic states of atomic uranium (including autoionisation levels), obtained from recent photoionisation experiments. The spacings distribution which reflects short-range structure appears to be Poisson but spectral fluctuation measures reveal rigidity, and are consistent with a superposition of GOE sequences as is typically seen in nuclear spectra.},
keywords = {Control, Optimization},
pubstate = {published},
tppubtype = {article}
}

@article{Sinha1987b,
title = {On the dynamics of a controlled metabolic network and cellular behaviour},
author = {S Sinha and R Ramaswamy},
url = {https://www.sciencedirect.com/science/article/pii/0303264787900529},
doi = {10.1016/0303-2647},
issn = {0303-2647},
year = {1987},
date = {1987-01-26},
journal = {Biosystems},
volume = {20},
number = {4},
pages = {341-354},
abstract = {The existence of elaborate control mechanisms for the various biochemical processes inside and within living cells is responsible for the coherent behaviour observed in its spatio-temporal organisation. Stability and sensitivity are both necessary properties of living systems and these are achieved through negetive and positive feedback loops as in other control systems. We have studied a three-step reaction scheme involving a negative and a positive feedback loop in the form of end-product inhibition and allosteric activation. The variety of behaviour exhibited by this system, under different conditions, includes steady state, simple limit cycle oscillations, complex oscillations and period bifurcations leading to random oscillations or chaos. The system also shows the existence of two distinct chaotic regimes under the variation of a single parameter. These results, in comparison with single biochemical control loops, show that new behaviours can be exhibited in a more complex network which are not seen in the single control loops. The results are discussed in the light of a diverse variety of cellular functions in normal and altered cells indicating the role of controlled metabolic network as the underlying basis for cellular behaviour.},
keywords = {Chaos, Control},
pubstate = {published},
tppubtype = {article}
}