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Variances in spectral analysis of membrane noise

Francesco Andrietti, Carla Canegallo (1984)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Le fluttuazioni di conduttanza di un modello di canale del potassio di una fibra muscolare che segue una cinetica di Hodgkin e Huxley sono state analizzate attraverso l'analisi spettrale indiretta. Sono state confrontate due diverse stime della densità spettrale e le loro rispettive varianze: quella della prima stima considerata è già nota, mentre quella della seconda stima è stata ricavata da noi nelle medesime ipotesi (distribuzione normale). I risultati teorici sono stati confrontati con quelli...

Variational Framework for Assessment of the Left Ventricle Motion

J. Garcia-Barnés, D. Gil, S. Pujadas, F. Carreras (2008)

Mathematical Modelling of Natural Phenomena

Impairment of left ventricular contractility due to cardiovascular diseases is reflected in left ventricle (LV) motion patterns. An abnormal change of torsion or long axis shortening LV values can help with the diagnosis and follow-up of LV dysfunction. Tagged Magnetic Resonance (TMR) is a widely spread medical imaging modality that allows estimation of the myocardial tissue local deformation. In this work, we introduce a novel variational framework for extracting the left ventricle dynamics from...

Variational Reduction for the Transport Equation in a Multiple Branching Plants Growth Model

S. Boujena, A. Chiboub, J. Pousin (2010)

Mathematical Modelling of Natural Phenomena

Plant growth depends essentially on nutrients coming from the roots and metabolites produced by the plant. Appearance of new branches is determined by concentrations of certain plant hormones. The most important of them are Auxin and Cytokinin. Auxin is produced in the growing, Cytokinin in either roots or in growing parts. Many dynamical models of this phenomena have been studied in [1]. In [5], the authors deal with one branch model. In this work,...

Verified solution method for population epidemiology models with uncertainty

Joshua A. Enszer, Mark A. Stadtherr (2009)

International Journal of Applied Mathematics and Computer Science

Epidemiological models can be used to study the impact of an infection within a population. These models often involve parameters that are not known with certainty. Using a method for verified solution of nonlinear dynamic models, we can bound the disease trajectories that are possible for given bounds on the uncertain parameters. The method is based on the use of an interval Taylor series to represent dependence on time and the use of Taylor models to represent dependence on uncertain parameters...

Viability, invariance and reachability for controlled piecewise deterministic Markov processes associated to gene networks

Dan Goreac (2012)

ESAIM: Control, Optimisation and Calculus of Variations

We aim at characterizing viability, invariance and some reachability properties of controlled piecewise deterministic Markov processes (PDMPs). Using analytical methods from the theory of viscosity solutions, we establish criteria for viability and invariance in terms of the first order normal cone. We also investigate reachability of arbitrary open sets. The method is based on viscosity techniques and duality for some associated linearized problem. The theoretical results are applied to general...

Viability, invariance and reachability for controlled piecewise deterministic Markov processes associated to gene networks

Dan Goreac (2012)

ESAIM: Control, Optimisation and Calculus of Variations

We aim at characterizing viability, invariance and some reachability properties of controlled piecewise deterministic Markov processes (PDMPs). Using analytical methods from the theory of viscosity solutions, we establish criteria for viability and invariance in terms of the first order normal cone. We also investigate reachability of arbitrary open sets. The method is based on viscosity techniques and duality for some associated linearized problem. The theoretical results are applied to general...

Viability, invariance and reachability for controlled piecewise deterministic Markov processes associated to gene networks

Dan Goreac (2012)

ESAIM: Control, Optimisation and Calculus of Variations

We aim at characterizing viability, invariance and some reachability properties of controlled piecewise deterministic Markov processes (PDMPs). Using analytical methods from the theory of viscosity solutions, we establish criteria for viability and invariance in terms of the first order normal cone. We also investigate reachability of arbitrary open sets. The method is based on viscosity techniques and duality for some associated linearized problem. The theoretical results are applied to general...

Vingt analyses multivariées d'une structure connue

H. Le Bras (1974)

Mathématiques et Sciences Humaines

L'usage croissant des analyses multivariées modifie la méthode de plusieurs sciences sociales. Le débat sur leur validité est toutefois assez confus car des questions de pure mathématique se mélangent à des problèmes perceptifs (représentation) et logiques (modélisation). Nous n'avons actuellement ni les moyens ni l'ambition d'aborder théoriquement leur statut, mais nous pensons fournir un document utile au débat en appliquant la majorité des méthodes à un même objet déjà connu et en comparant leur...

Volume Filling Effect in Modelling Chemotaxis

D. Wrzosek (2010)

Mathematical Modelling of Natural Phenomena

The oriented movement of biological cells or organisms in response to a chemical gradient is called chemotaxis. The most interesting situation related to self-organization phenomenon takes place when the cells detect and response to a chemical which is secreted by themselves. Since pioneering works of Patlak (1953) and Keller and Segel (1970) many particularized models have been proposed to describe the aggregation phase of this process. Most of...

Von Bertalanffy's growth dynamics with strong Allee effect

J. Leonel Rocha, Sandra M. Aleixo (2012)

Discussiones Mathematicae Probability and Statistics

Von Bertalanffy’s model is one of the most popular differential equation used in order to study the increase in average length or weight of fish. However, this model does not include demographic Allee effect. This phenomenon is known in the fisheries literature as “depensation”, which arises when populations decline rapidly at low densities. In this paper we develop and investigate new corrected von Bertalanffy’s models with Allee effects. The generalization that we propose results from considering...

Wave of Chaos and Pattern Formation in Spatial Predator-Prey Systems with Holling Type IV Predator Response

R. K. Upadhyay, N. Kumari, V. Rai (2008)

Mathematical Modelling of Natural Phenomena

The challenges to live in the open water and the diversity of habitats in the marine environments prompts phytoplankton to devise strategies which often involve production of toxins by Harmful Algal Bloom (HAB) and rapid production of metabolites from non-toxic precursor. The functional response of the predator is described by Holling type IV. We investigate wave phenomena and non-linear non-equilibrium pattern formation in a phytoplankton-zooplankton system with Holling type IV functional response....

Waves of Autocrine Signaling in Patterned Epithelia

C. B. Muratov, S. Y. Shvartsman (2010)

Mathematical Modelling of Natural Phenomena

A biophysical model describing long-range cell-to-cell communication by a diffusible signal mediated by autocrine loops in developing epithelia in the presence of a morphogenetic pre-pattern is introduced. Under a number of approximations, the model reduces to a particular kind of bistable reaction-diffusion equation with strong heterogeneity. In the case of the heterogeneity in the form of a long strip a detailed analysis of signal propagation is...

Weighted Elastic Net Model for Mass Spectrometry Imaging Processing

D. Hong, F. Zhang (2010)

Mathematical Modelling of Natural Phenomena

In proteomics study, Imaging Mass Spectrometry (IMS) is an emerging and very promising new technique for protein analysis from intact biological tissues. Though it has shown great potential and is very promising for rapid mapping of protein localization and the detection of sizeable differences in protein expression, challenges remain in data processing due to the difficulty of high dimensionality and the fact that the number of input variables in...

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