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"optimal control theory"

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https://www.readbyqxmd.com/read/27864095/optimization-of-an-in-vitro-chemotherapy-to-avoid-resistant-tumours
#1
Cécile Carrère
Chemotherapy use against solid tumours often results in the resistance of the cancer cells to the molecule used. In this paper, we will set up and analyse an ODE model for heterogeneous in vitro tumours, consisting of cells that are sensitive or resistant to a certain drug. We will then use this model to develop different protocols, that aim at reducing the tumour volume while preserving its heterogeneity. These drug administration schedules are determined through analysis of the system dynamics, and optimal control theory...
November 15, 2016: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/27725688/optimal-control-of-complex-atomic-quantum-systems
#2
S van Frank, M Bonneau, J Schmiedmayer, S Hild, C Gross, M Cheneau, I Bloch, T Pichler, A Negretti, T Calarco, S Montangero
Quantum technologies will ultimately require manipulating many-body quantum systems with high precision. Cold atom experiments represent a stepping stone in that direction: a high degree of control has been achieved on systems of increasing complexity. However, this control is still sub-optimal. In many scenarios, achieving a fast transformation is crucial to fight against decoherence and imperfection effects. Optimal control theory is believed to be the ideal candidate to bridge the gap between early stage proof-of-principle demonstrations and experimental protocols suitable for practical applications...
October 11, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27713655/quantifying-uncertainty-in-partially-specified-biological-models-how-can-optimal-control-theory-help-us
#3
M W Adamson, A Y Morozov, O A Kuzenkov
Mathematical models in biology are highly simplified representations of a complex underlying reality and there is always a high degree of uncertainty with regards to model function specification. This uncertainty becomes critical for models in which the use of different functions fitting the same dataset can yield substantially different predictions-a property known as structural sensitivity. Thus, even if the model is purely deterministic, then the uncertainty in the model functions carries through into uncertainty in model predictions, and new frameworks are required to tackle this fundamental problem...
September 2016: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/27176250/feedback-control-of-waiting-times
#4
Tobias Brandes, Clive Emary
Feedback loops are known as a versatile tool for controlling transport in small systems, which usually have large intrinsic fluctuations. Here we investigate the control of a temporal correlation function, the waiting-time distribution, under active and passive feedback conditions. We develop a general formalism and then specify to the simple unidirectional transport model, where we compare costs of open-loop and feedback control and use methods from optimal control theory to optimize waiting-time distributions...
April 2016: Physical Review. E
https://www.readbyqxmd.com/read/27143501/controlling-open-quantum-systems-tools-achievements-and-limitations
#5
Christiane P Koch
The advent of quantum devices, which exploit the two essential elements of quantum physics, coherence and entanglement, has sparked renewed interest in the control of open quantum systems. Successful implementations face the challenge of preserving relevant nonclassical features at the level of device operation. A major obstacle is decoherence, which is caused by interaction with the environment. Optimal control theory is a tool that can be used to identify control strategies in the presence of decoherence...
June 2, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/27131527/time-optimal-excitation-of-maximum-quantum-coherence-physical-limits-and-pulse-sequences
#6
S S Köcher, T Heydenreich, Y Zhang, G N M Reddy, S Caldarelli, H Yuan, S J Glaser
Here we study the optimum efficiency of the excitation of maximum quantum (MaxQ) coherence using analytical and numerical methods based on optimal control theory. The theoretical limit of the achievable MaxQ amplitude and the minimum time to achieve this limit are explored for a set of model systems consisting of up to five coupled spins. In addition to arbitrary pulse shapes, two simple pulse sequence families of practical interest are considered in the optimizations. Compared to conventional approaches, substantial gains were found both in terms of the achieved MaxQ amplitude and in pulse sequence durations...
April 28, 2016: Journal of Chemical Physics
https://www.readbyqxmd.com/read/26932466/input-estimation-for-drug-discovery-using-optimal-control-and-markov-chain-monte-carlo-approaches
#7
Magnus Trägårdh, Michael J Chappell, Andrea Ahnmark, Daniel Lindén, Neil D Evans, Peter Gennemark
Input estimation is employed in cases where it is desirable to recover the form of an input function which cannot be directly observed and for which there is no model for the generating process. In pharmacokinetic and pharmacodynamic modelling, input estimation in linear systems (deconvolution) is well established, while the nonlinear case is largely unexplored. In this paper, a rigorous definition of the input-estimation problem is given, and the choices involved in terms of modelling assumptions and estimation algorithms are discussed...
April 2016: Journal of Pharmacokinetics and Pharmacodynamics
https://www.readbyqxmd.com/read/26890347/optimal-schedules-in-multitask-motor-learning
#8
Jeong Yoon Lee, Youngmin Oh, Sung Shin Kim, Robert A Scheidt, Nicolas Schweighofer
Although scheduling multiple tasks in motor learning to maximize long-term retention of performance is of great practical importance in sports training and motor rehabilitation after brain injury, it is unclear how to do so. We propose here a novel theoretical approach that uses optimal control theory and computational models of motor adaptation to determine schedules that maximize long-term retention predictively. Using Pontryagin's maximum principle, we derived a control law that determines the trial-by-trial task choice that maximizes overall delayed retention for all tasks, as predicted by the state-space model...
April 2016: Neural Computation
https://www.readbyqxmd.com/read/26796222/optimal-control-with-multiple-human-papillomavirus-vaccines
#9
Tufail Malik, Mudassar Imran, Raja Jayaraman
A two-sex, deterministic ordinary differential equations model for human papillomavirus (HPV) is constructed and analyzed for optimal control strategies in a vaccination program administering three types of vaccines in the female population: a bivalent vaccine that targets two HPV types and provides longer duration of protection and cross-protection against some non-target types, a quadrivalent vaccine which targets an additional two HPV types, and a nonavalent vaccine which targets nine HPV types (including those covered by the quadrivalent vaccine), but with lesser type-specific efficacy...
March 21, 2016: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/26715209/direct-methods-for-predicting-movement-biomechanics-based-upon-optimal-control-theory-with-implementation-in-opensim
#10
Sina Porsa, Yi-Chung Lin, Marcus G Pandy
The aim of this study was to compare the computational performances of two direct methods for solving large-scale, nonlinear, optimal control problems in human movement. Direct shooting and direct collocation were implemented on an 8-segment, 48-muscle model of the body (24 muscles on each side) to compute the optimal control solution for maximum-height jumping. Both algorithms were executed on a freely-available musculoskeletal modeling platform called OpenSim. Direct collocation converged to essentially the same optimal solution up to 249 times faster than direct shooting when the same initial guess was assumed (3...
August 2016: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/26676356/optimal-control-for-an-age-structured-model-for-the-transmission-of-hepatitis-b
#11
Ramses Djidjou Demasse, Jean-Jules Tewa, Samuel Bowong, Yves Emvudu
One of the characteristics of HBV transmission is the age structure of the host population and the vertical transmission of the disease. That is the infection is transmitted directly from infected mother to an embryo, fetus, or baby during pregnancy or childbirth (the perinatal infection). We formulated an age-structured model for the transmission dynamics of HBV with differential infectivity: symptomatic and asymptomatic infections. The model without intervention strategies is completely analyzed. We compute the basic reproduction number which determines the outcome of the disease...
August 2016: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/26655362/new-developments-in-the-application-of-optimal-control-theory-to-therapeutic-protocols
#12
L Bayón, J A Otero, P M Suárez, C Tasis
Optimal control theory is one of the most important tools in the development of new therapeutic protocols for treating infections. In this work, we present an algorithm able to deal with high-dimensional problems with bounded controls. The optimal solution is obtained by minimizing a positive-definite treatment cost function. Our method, based on Pontryagin's Minimum Principle and the coordinate cyclic descent method, allows solving problems of varied nature. In this paper, and by way of example, therapeutic enhancement of the immune response to invasion by pathogenic attack is addressed as an optimal control problem...
February 2016: Mathematical Biosciences
https://www.readbyqxmd.com/read/26551557/stability-analysis-and-optimal-control-of-an-epidemic-model-with-awareness-programs-by-media
#13
A K Misra, Anupama Sharma, J B Shukla
The impact of awareness campaigns and behavioral responses on epidemic outbreaks has been reported at times. However, to what extent does the provision of awareness and behavioral changes affect the epidemic trajectory is unknown, but important from the public health standpoint. To address this question, we formulate a mathematical model to study the effect of awareness campaigns by media on the outbreak of an epidemic. The awareness campaigns are treated as an intervention for the emergent disease. These awareness campaigns divide the whole populations into two subpopulation; aware and unaware, by inducing behavioral changes amongst them...
December 2015: Bio Systems
https://www.readbyqxmd.com/read/26548947/constrained-growth-flips-the-direction-of-optimal-phenological-responses-among-annual-plants
#14
Magnus Lindh, Jacob Johansson, Kjell Bolmgren, Niklas L P Lundström, Åke Brännström, Niclas Jonzén
Phenological changes among plants due to climate change are well documented, but often hard to interpret. In order to assess the adaptive value of observed changes, we study how annual plants with and without growth constraints should optimize their flowering time when productivity and season length changes. We consider growth constraints that depend on the plant's vegetative mass: self-shading, costs for nonphotosynthetic structural tissue and sibling competition. We derive the optimal flowering time from a dynamic energy allocation model using optimal control theory...
March 2016: New Phytologist
https://www.readbyqxmd.com/read/26520515/photodissociation-of-the-carbon-monoxide-dication-in-the-3-%C3%AE-manifold-quantum-control-simulation-towards-the-c-2-o-channel
#15
S Vranckx, J Loreau, N Vaeck, C Meier, M Desouter-Lecomte
The photodissociation and laser assisted dissociation of the carbon monoxide dication X(3)Π CO(2+) into the (3)Σ(-) states are investigated. Ab initio electronic structure calculations of the adiabatic potential energy curves, radial nonadiabatic couplings, and dipole moments for the X (3)Π state are performed for 13 excited (3)Σ(-) states of CO(2+). The photodissociation cross section, calculated by time-dependent methods, shows that the C(+) + O(+) channels dominate the process in the studied energy range...
October 28, 2015: Journal of Chemical Physics
https://www.readbyqxmd.com/read/26441407/elastic-stability-of-concentric-tube-robots-subject-to-external-loads
#16
Junhyoung Ha, Frank C Park, Pierre E Dupont
Concentric tube robots, which are comprised of precurved elastic tubes that are concentrically arranged, are being developed for many medical interventions. The shape of the robot is determined by the rotation and translation of the tubes relative to each other, and also by any external forces applied by the environment. As the tubes rotate and translate relative to each other, elastic potential energy caused by tube bending and twisting can accumulate; if a configuration is not locally elastically stable, then a dangerous snapping motion may occur as energy is suddenly released...
June 2016: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/26402322/modeling-and-computation-of-transboundary-industrial-pollution-with-emission-permits-trading-by-stochastic-differential-game
#17
Shuhua Chang, Xinyu Wang, Zheng Wang
Transboundary industrial pollution requires international actions to control its formation and effects. In this paper, we present a stochastic differential game to model the transboundary industrial pollution problems with emission permits trading. More generally, the process of emission permits price is assumed to be stochastic and to follow a geometric Brownian motion (GBM). We make use of stochastic optimal control theory to derive the system of Hamilton-Jacobi-Bellman (HJB) equations satisfied by the value functions for the cooperative and the noncooperative games, respectively, and then propose a so-called fitted finite volume method to solve it...
2015: PloS One
https://www.readbyqxmd.com/read/26354914/apparent-and-actual-trajectory-control-depend-on-the-behavioral-context-in-upper-limb-motor-tasks
#18
Tyler Cluff, Stephen H Scott
A central problem in motor neuroscience is to understand how we select, plan, and control motor actions. An influential idea is that the motor system computes and implements a desired limb trajectory, an intermediary control process between the behavioral goal (reach a spatial goal) and motor commands to move the limb. The most compelling evidence for trajectory control is that corrective responses are directed back toward the unperturbed trajectory when the limb is disturbed during movement. However, the idea of trajectory control conflicts with optimal control theories that emphasize goal-directed motor corrections...
September 9, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/26328824/auxiliary-matrix-formalism-for-interaction-representation-transformations-optimal-control-and-spin-relaxation-theories
#19
D L Goodwin, Ilya Kuprov
Auxiliary matrix exponential method is used to derive simple and numerically efficient general expressions for the following, historically rather cumbersome, and hard to compute, theoretical methods: (1) average Hamiltonian theory following interaction representation transformations; (2) Bloch-Redfield-Wangsness theory of nuclear and electron relaxation; (3) gradient ascent pulse engineering version of quantum optimal control theory. In the context of spin dynamics, the auxiliary matrix exponential method is more efficient than methods based on matrix factorizations and also exhibits more favourable complexity scaling with the dimension of the Hamiltonian matrix...
August 28, 2015: Journal of Chemical Physics
https://www.readbyqxmd.com/read/26322192/a-novel-scheme-for-optimal-control-of-a-nonlinear-delay-differential-equations-model-to-determine-effective-and-optimal-administrating-chemotherapy-agents-in-breast-cancer
#20
H R Ramezanpour, S Setayeshi, M E Akbari
BACKGROUND: Determining the optimal and effective scheme for administrating the chemotherapy agents in breast cancer is the main goal of this scientific research. The most important issue here is the amount of drug or radiation administrated in chemotherapy and radiotherapy for increasing patient's survival. This is because in these cases, the therapy not only kills the tumor cells, but also kills some of the healthy tissues and causes serious damages. In this paper we investigate optimal drug scheduling effect for breast cancer model which consist of nonlinear ordinary differential time-delay equations...
2011: Iranian Journal of Cancer Prevention
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