We explore the feasibility of using fast-slow asymptotics to eliminate the computational stiffness of discrete-state, continuous-time deterministic Markov chain models of ionic channels underlying cardiac excitability. We focus on a Markov chain model of fast sodium current, and investigate its asymptotic behaviour with respect to small parameters identified in different ways.
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http://dx.doi.org/10.1063/1.5003013 | DOI Listing |
Bull Math Biol
January 2025
Section of Epidemiology, University of Copenhagen, Copenhagen, Denmark.
Using genetic data to infer evolutionary distances between molecular sequence pairs based on a Markov substitution model is a common procedure in phylogenetics, in particular for selecting a good starting tree to improve upon. Many evolutionary patterns can be accurately modelled using substitution models that are available in closed form, including the popular general time reversible model (GTR) for DNA data. For more complex biological phenomena, such as variations in lineage-specific evolutionary rates over time (heterotachy), other approaches such as the GTR with rate variation (GTR ) are required, but do not admit analytical solutions and do not automatically allow for likelihood calculations crucial for Bayesian analysis.
View Article and Find Full Text PDFBull Math Biol
January 2025
Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA, USA.
Neuroinflammation immediately follows the onset of ischemic stroke in the middle cerebral artery. During this process, microglial cells are activated in and recruited to the penumbra. Microglial cells can be activated into two different phenotypes: M1, which can worsen brain injury; or M2, which can aid in long-term recovery.
View Article and Find Full Text PDFBMC Ophthalmol
January 2025
Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.
Purpose: To assess the clinical efficacy of 0.1% cyclosporine A (CsA) in dry eye patients who have shown inadequate responses to previous treatment with 0.05% CsA.
View Article and Find Full Text PDFBMJ Open
January 2025
Department of Oncology, Hanoi Medical University, Hanoi, Vietnam.
Background: Cervical cancer (CC) is preventable through regular screening and vaccination against human papillomavirus (HPV). However, CC remains a significant public health issue in low-income and middle-income countries (LMICs) like Vietnam, where financial constraints hinder the widespread implementation of HPV vaccination and screening programmes. Currently, Vietnam lacks both a national CC screening intervention and an HPV vaccination programme for women and girls.
View Article and Find Full Text PDFPLoS One
January 2025
Department of Surgery, Asian Liver Center, Stanford University School of Medicine, Stanford, California, United States of America.
Patients with chronic hepatitis B infection (CHB) have an increased risk for death from liver cirrhosis and hepatocellular carcinoma (HCC). In the United States, only an estimated 37% of adults with chronic hepatitis B diagnosis without cirrhosis receive monitoring with at least an annual alanine transaminase (ALT) and hepatitis B deoxyribonucleic acid (DNA), and an estimated 59% receive antiviral treatment when they develop active hepatitis or cirrhosis. A Markov model was used to calculate the costs, health impact and cost-effectiveness of increased monitoring of adults with HBeAg negative inactive or HBeAg positive immune tolerant CHB who have no cirrhosis or significant fibrosis and are not recommended by the current American Association for the Study of Liver Diseases (AASLD) clinical practice guidelines to receive antiviral treatment, and to assess whether the addition of HCC surveillance would be cost-effective.
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