Estimating parameters of nonlinear dynamic systems in pharmacology using chaos synchronization and grid search

AbstractBridging fundamental approaches to model optimization for pharmacometricians, systems pharmacologists and statisticians is a critical issue. These fields rely primarily on Maximum Likelihood and Extended Least Squares metrics with iterative estimation of parameters. Our research combines adaptive chaos synchronization and grid search to estimate physiological and pharmacological systems with emergent properties by exploring deterministic methods that are more appropriate and have potentially superior performance than classical numerical approaches, which minimize the sum of squares or maximize the likelihood. We illustrate these issues with an established model of cortisol in human with nonlinear dynamics. The model describes cortisol kinetics over time, including its chaotic oscillations, by a delay differential equation. We demonstrate that chaos synchronization helps to avoid the tendency of the gradient-based optimization algorithms to end up in a local minimum. The subsequent analysis illustrates that the hybrid adaptive chaos synchronization for estimation of linear parameters with coarse-to-fine grid search for optimal values of non-linear parameters can be applied iteratively to accurately estimate parameters and effectively track trajectories for a wide class of noisy chaotic systems.
Source: Journal of Pharmacokinetics and Pharmacodynamics - Category: Drugs & Pharmacology Source Type: research

Related Links:

Authors: Stefano GB, Esch T, Kream RM Abstract The relaxation response derives its health benefits by reestablishing "normal" equilibria between the sympathetic and parasympathetic branches of the autonomic nervous system. Recent work suggests that this behavioral training provides positive effects on mitochondrial bioenergetics, insulin secretion, and reductions in pro-inflammatory and stress-related pathways. We have previously contended, however, that correlative associations of relaxation training with positive changes in gene expression in selected biological systems are strongly suggestive of adapti...
Source: Medical Science Monitor - Category: Research Tags: Med Sci Monit Source Type: research
Authors: Xu J, Wang X, Xiao H, Xu J Abstract BACKGROUND To determine the difference in size-specific dose estimates (SSDEs), separately based on effective diameter (deff) and water equivalent diameter (dw) of the central slice of the scan range in computed tomography coronary angiography (CTCA). MATERIAL AND METHODS There were 134 patients who underwent CTCA examination, were electronically retrieved. SSDEs (SSDEdeff and SSDEdw) were calculated using 2 approaches: deff and dw. The median SSDEs and mean absolute relative difference of SSDEs were calculated. Linear regression model was used to assess the absolute rel...
Source: Medical Science Monitor - Category: Research Tags: Med Sci Monit Source Type: research
Resveratrol Protects the Myocardium in Sepsis by Activating the Phosphatidylinositol 3-Kinases (PI3K)/AKT/Mammalian Target of Rapamycin (mTOR) Pathway and Inhibiting the Nuclear Factor-κB (NF-κB) Signaling Pathway. Med Sci Monit. 2019 Dec 06;25:9290-9298 Authors: Shang X, Lin K, Yu R, Zhu P, Zhang Y, Wang L, Xu J, Chen K Abstract BACKGROUND Sepsis combined with myocardial injury is an important cause of septic shock and multiple organ failure. However, the molecular mechanism of sepsis-induced myocardial dysfunction has not yet been thoroughly studied. Resveratrol has been an important rese...
Source: Medical Science Monitor - Category: Research Tags: Med Sci Monit Source Type: research
Authors: Pountney M PMID: 31809596 [PubMed - in process]
Source: Medicine, Conflict and Survival - Category: International Medicine & Public Health Tags: Med Confl Surviv Source Type: research
Authors: Birch M, van Bergen L PMID: 31809595 [PubMed - in process]
Source: Medicine, Conflict and Survival - Category: International Medicine & Public Health Tags: Med Confl Surviv Source Type: research
This study assessed the prevalence, risk factors, and co-infectivity of CTBP such as piroplasms, rickettsiae, Coxiella burnetii, hepatozoa, hemotropic mycoplasmas, and Borrelia spp., using PCR and phylogenetic analyses. Of the 510 dogs tested, three CTBP, including Anaplasma phagocytophilum 16S rRNA (13; 2.6%), Hepatozoon canis 18S rRNA (2; 0.4%), and Mycoplasma haemocanis 16S rRNA (1; 0.2%) were detected. PCR adapted to amplify A. phagocytophilum msp2 and groEL genes generated amplicons thereof in two out of 13 positive dogs. One shelter dog was co-infected with A. phagocytophilum and M. haemocanis. However, Ehrlichia spp...
Source: Ticks and Tick borne Diseases - Category: Zoology Source Type: research
Publication date: Available online 6 December 2019Source: Ticks and Tick-borne DiseasesAuthor(s): Hein Sprong, Sander Moonen, Sipke E. van Wieren, Tim R. HofmeesterAbstractCattle grazing has been suggested to reduce the risk for Lyme borreliosis by decreasing the density of questing Ixodes ricinus infected with Borrelia burgdorferi sensu lato. We tested the hypotheses that cattle grazing used in woodland management decreases the density of questing I. ricinus, and that it decreases the nympal infection prevalence of B. burgdorferi sensu lato. We further expected the nympal infection prevalence of tick-borne pathogens that ...
Source: Ticks and Tick borne Diseases - Category: Zoology Source Type: research
Publication date: Available online 6 December 2019Source: Ticks and Tick-borne DiseasesAuthor(s): Amber M. Frye, Thomas M. Hart, Danielle M. Tufts, Sanjay Ram, Maria A. Diuk-Wasser, Peter Kraiczy, Anna M. Blom, Yi-Pin LinAbstractComplement is a key first line innate host defense system in the blood of vertebrates. Upon activation, this powerful defense mechanism can elicit inflammatory responses, lyse non-self-cells, or mark them for opsonophagocytic removal. Blood-feeding arthropods thus require the ability to block host complement activation in the bloodmeal to prevent undesired cell or tissue damage during feeding. The ...
Source: Ticks and Tick borne Diseases - Category: Zoology Source Type: research
"TAVI: Valve in Valve. A new field for structuralists? Literature review". Hellenic J Cardiol. 2019 Dec 03;: Authors: Vrachatis DA, Vavuranakis M, Tsoukala S, Sotiria G, Papaioannou TG, Siasos G, Deftereos G, Giannopoulos G, Raisakis K, Tousoulis D, Deftereos S, Vavuranakis M Abstract Transcatheter aortic valve implantation (TAVI) literally founded the structural heart interventions subspecialty and created an emerging journey of clinical and technical issues. Soon after TAVI introduction into clinical practice, boundaries were expanded with utilization of valve-in-valve (V-i-V) techniques. V...
Source: Hellenic Journal of Cardiology - Category: Cardiology Tags: Hellenic J Cardiol Source Type: research
Transparent substrates introduce challenges in optical metrology, recording, and microscopy. Backside reflections reduce signal to noise, ...
Source: Optics Letters - Category: Physics Authors: Source Type: research
More News: Drugs & Pharmacology | Statistics