A5043942924- Nonlinear Dynamics and Pattern Formation
- Neural dynamics and brain function
- Model Reduction and Neural Networks
- stochastic dynamics and bifurcation
- Neuroscience and Neural Engineering
- Insect behavior and control techniques
- Insect Pest Control Strategies
- Probabilistic and Robust Engineering Design
- Neurological disorders and treatments
- Cardiac electrophysiology and arrhythmias
- Fluid Dynamics and Vibration Analysis
- Circadian rhythm and melatonin
- Fluid Dynamics and Turbulent Flows
- Insect-Plant Interactions and Control
- Heart Rate Variability and Autonomic Control
- Geriatric Care and Nursing Homes
- Chaos control and synchronization
- Advanced Memory and Neural Computing
- Control Systems and Identification
- Insect Utilization and Effects
- Agricultural pest management studies
- Chronic Disease Management Strategies
- Chronic Kidney Disease and Diabetes
- Date Palm Research Studies
- Frailty in Older Adults
University of Tennessee at Knoxville
2018-2025
King's College Hospital NHS Foundation Trust
2008-2025
Alice Springs Hospital
2024
University of Virginia Health System
2024
Bayer (United States)
2023-2024
Library of Virginia
2023
University of Virginia
2018-2023
Knoxville College
2021
University of Ghana
2005-2020
University of Pittsburgh
2017
UK and global policies recommend whole-school approaches to improve childrens' inadequate physical activity (PA) levels. Yet, recent meta-analyses establish current interventions as ineffective due suboptimal implementation rates poor sustainability. To create effective interventions, which recognise schools complex adaptive sub-systems, multi-stakeholder input is necessary. Further, ensure 'systems' change, a framework required that identifies all components of PA approach. The study's aim...
We propose a novel, closed-loop approach to tuning deep brain stimulation (DBS) for Parkinson's disease (PD). The approach, termed Phasic Burst Stimulation (PhaBS), applies burst of stimulus pulses over range phases predicted disrupt pathological oscillations seen in PD. parameters are optimized based on phase response curves (PRCs), which would be measured from each patient. This is tested computational model PD with an emergent population oscillation. show that the can using PRC, and PhaBS...
The well-established method of phase reduction neglects information about a limit-cycle oscillator's approach towards its periodic orbit. Consequently, suffers in practicality unless the magnitude Floquet multipliers underlying limit cycle are small magnitude. By defining isostable coordinates orbit, we present an augmentation to classical which obviates this restriction on multipliers. This framework allows for study and understanding dynamics standard alone is inadequate. Most notably,...
Delirium is increasingly considered to be an important determinant of trajectories cognitive decline. Therefore, analyses existing cohort studies measuring outcomes could benefit from methods ascertain a retrospective delirium diagnosis. This study aimed develop and validate such method for detection using routine medical records in UK Ireland.A point prevalence provided the reference-standard ratings Blinded results, clinical vignettes were compiled participants' standardised manner,...
A procedure is developed for finding an energy-optimal stimulus which gives a positive Lyapunov exponent, and hence desynchronization, neural population. The illustrated three different models. Not only does it achieve desynchronization each model, but also so using less energy than recently proposed methods, suggesting powerful alternative to pulsatile stimuli deep brain stimulation. Furthermore, we calculate error bounds on the optimal will guarantee minimum exponent. Also, related control...
While phase reduction is a well-established technique for the analysis of perturbed limit cycle oscillators, practical application requires perturbations to be sufficiently weak thereby limiting its utility in many situations. Here, general strategy developed constructing set phase-amplitude reduced equations that valid arbitrary orders accuracy amplitude coordinates. This framework can used investigate behavior oscillatory dynamical systems far beyond weakly paradigm. Additionally,...
Emergency departments (EDs) in England are under significant strain, with increasing attendances and extended wait times, affecting frail older adults. The clinical frailty scale (CFS) has been implemented as a tool to assess ED settings, but its reliability predictive accuracy screening remain debated. To evaluate the use variability of CFS EDs association patient outcomes, including discharge rates, length stay, readmission mortality. A retrospective cohort study at two London (UK)...
While high-frequency deep brain stimulation is a well established treatment for Parkinson's disease, its underlying mechanisms remain elusive. Here, we show that two competing hypotheses, desynchronization and entrainment in population of model neurons, may not be mutually exclusive. We find noisy group phase oscillators, high frequency perturbations can separate the into multiple clusters, each with nearly identical proportion overall population. This phenomenon understood by studying maps...
We review the theory of weakly coupled oscillators for smooth systems. then examine situations where application standard falls short and illustrate how it can be extended. Specific examples are given to non-smooth systems with applications Izhikevich neuron. introduce idea isostable reduction explore behaviours that weak coupling paradigm cannot explain. In an additional example, we show bifurcations change stability phase-locked solutions in a pair identical neurons understood using notion...
While phase reduction is a tremendously useful tool for understanding the dynamics of weakly perturbed limit cycle oscillators, its assumptions break down as perturbations become larger, limiting practical utility in many applications. This fundamental limitation often apparent when studying coupled populations oscillators collective behavior approaches with transient that decays slowly. Using notion isostables periodic orbits, which define coordinate system transverse to cycle, we develop...
We use the theory of isostable reduction to incorporate higher order effects that are lost in first phase coupled oscillators. apply this weakly complex Ginzburg-Landau equations, a pair conductance-based neural models, and finally short derivation Kuramoto-Sivashinsky equations. Numerical analytical examples illustrate bifurcations occurring oscillator networks can cause standard phase-reduction methods fail.
Phase-amplitude reduction is of growing interest as a strategy for the and analysis oscillatory dynamical systems. Augmentation widely studied phase with amplitude coordinates can be used to characterize transient behavior in directions transverse limit cycle give richer description behavior. Various definitions have been suggested, but none are particularly well suited implementation experimental systems where output recordings readily available underlying equations typically unknown. In...
We use optimal control theory to design a methodology find locally stimuli for desynchronization of model neurons with extracellular stimulation. This yields which lead positive Lyapunov exponents, and hence desynchronizes neural population. analyze this in the presence interneuron coupling make predictions about strength stimulation required overcome synchronizing effects coupling. suggests powerful alternative pulsatile deep brain as it uses less energy than stimuli, could eliminate time...
Phase-amplitude reduction is a widely applied technique in the study of limit cycle oscillators with ability to represent complicated and high-dimensional dynamical system more analytically tractable set coordinates. Recent work has focused on use isostable coordinates, which characterize transient decay solutions toward periodic orbit, can ultimately be used increase accuracy these reduced models. The breadth systems this phase-amplitude strategy applied, however, still rather limited. In...
We develop a methodology to design stimulus optimized entrain nonlinear, noisy limit cycle oscillators with uncertain properties. Conditions are derived which guarantee that the will despite these uncertainties. Using conditions, we an energy optimal control strategy efficient entraining and apply it numerical models of phase in vitro hippocampal neurons. In both instances, stimuli outperform other similar but suboptimal stimuli. Because this explicitly accounts for noise inherent...
Phase reduction methods have been tremendously useful for understanding the dynamics of nonlinear oscillators, but difficult to extend systems with a stable fixed point, such as an excitable system. Using notion isostables, which measure time it takes given initial condition in phase space approach we present general method isostable systems. We also devise adjoint calculating infinitesimal response curves, are analogous curves oscillatory Through reduction, able implement sophisticated...
An Adaptive Phase-Amplitude Reduction Framework without $\mathcal{O}(\epsilon)$ Constraints on Inputs
.While many well-established approaches exist for phase-based reduced order modeling of tonically firing neurons, comparatively few general the consideration bursting neurons in a setting. Many formal analysis strategies exploit separation fast and slow timescales present most but these are typically ill-suited to consider emergent behavior resulting from inter-neuron coupling or other external perturbations. This work considers development two different model reduction valid topological...