Mathematical Medicine and Biology - recent issuesMathematical Medicine and Biology - RSS feed of recent issues (covers the latest 3 issues, including the current issue)Calcium release site ultrastructure and the dynamics of puffs and sparks- May 21, 2008 When Markov chain models of intracellular Ca2+-regulated Ca2+ channels are coupled via a mathematical representation of a Ca2+ microdomain, simulated Ca2+ release sites may exhibit the phenomenon of ‘stochastic Ca2+ excitability’ reminiscent of Ca2+ puffs and sparks. Interestingly, some single-channel models that include Ca2+ inactivation are not particularly sensitive to channel density, so long as the requirement for inter-channel communication is satisfied, while other...http://imammb.oxfordjournals.org/cgi/content/short/25/1/65?rss=1 Shortening of cardiac action potential duration near an insulating boundary- May 21, 2008 It is known, from both experiments and simulations, that cardiac action potentials are shortened near a non-conducting boundary. In the present paper, this effect is studied in a simple, two-current ionic model, with propagation restricted to a 1D fibre. An asymptotic approximation for the dependence of action potential duration on distance to the boundary is derived. This estimate agrees well with simulations.http://imammb.oxfordjournals.org/cgi/content/short/25/1/21?rss=1 Control of invasive hosts by generalist parasitoids- May 21, 2008 This article was motivated by the invasion of leaf-mining microlepidopteron attacking horse chestnut trees in Europe and the need for a biological control. Following Owen & Lewis (2001, Bull. Math. Biol., 63, 655–684), we consider predation of leafminers by a generalist parasitoid with a Holling Type II functional response. We first identified six equilibrium points and discussed their stabilities in the non-spatial model. The model always predicts persistence of the parasitoid....http://imammb.oxfordjournals.org/cgi/content/short/25/1/1?rss=1 Variability in the secretion of corticotropin-releasing hormone, adrenocorticotropic hormone and cortisol and understandability of the hypothalamic-pi- May 21, 2008 In this article, we have developed a simple mathematical model that captures the vital mechanisms of the hypothalamic-pituitary-adrenal (HPA) axis self-regulatory activities. For this, a system of three-component non-linear delay differential equations has been proposed and analysed to observe the ultradian and circadian variabilities of the hormone secretion of the HPA axis in normal subjects. Our analysis reveals that a feedback mechanism is sufficient to show the ultradian variability of the.http://imammb.oxfordjournals.org/cgi/content/short/25/1/37?rss=1 Analysis of extrema of heartbeat time series in exercise test- May 21, 2008 The heartbeat time series of the electrocardiogram recorded during exercise test clearly reflects the physiological control mechanism of the autonomic nervous system on heart rate. This series shows both decreasing and increasing trends and variability of the variance. We analyse the series of intervals between two consecutive extrema, i.e. the durations of accelerations or decelerations of heart rate. We compute the distribution of the length of these intervals and their mean in a model of...http://imammb.oxfordjournals.org/cgi/content/short/25/1/87?rss=1 |