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Displaying 1021 –
1040 of
1854
Studying the evolutive and adaptative machanisms of prokayotes is a complicated task.
As these machanisms cannot be easily studied "in vivo", it is necessary to consider other methods.
We have therefore developed the RAevol model, a model designed to study the evolution of bacteria and their adaptationto the environment.
Our model simulates the evolution of a population of artificial bacteria in a changing environment, providing us with an insight into the strategies that digital organisms develop...
Since cancer is a complex phenomenon that incorporates events occurring on different
length and time scales, therefore multiscale models are needed if we hope to adequately address
cancer specific questions. In this paper we present three different multiscale individual-cell-based
models, each motivated by cancer-related problems emerging from each of the spatial scales: extracellular,
cellular or subcellular, but also incorporating relevant information from other levels.
We apply these hybrid...
This paper is devoted to solving of dynamic problems in biomechanics that require
detailed study of fast processes. Numerical method of characteristics is used to model the
temporal development of the processes with high accuracy.
Plant growth occurs due to cell proliferation in the meristem. We model the case of
apical meristem specific for branch growth and the case of basal meristem specific for
bulbous plants and grass. In the case of apical growth, our model allows us to describe
the variety of plant forms and lifetimes, endogenous rhythms and apical domination. In the
case of basal growth, the spatial structure, which corresponds to the appearance of
leaves, results...
This review aims at presenting a
synoptic, if not exhaustive, point of view on some of the problems
encountered by biologists and physicians who deal with natural
cell proliferation and disruptions of its physiological control in
cancer disease. It also aims at suggesting how mathematicians are
naturally challenged by these questions and how they might help,
not only biologists to deal theoretically with biological
complexity, but also physicians to optimise therapeutics, on which
last point the...
Over the past decade or so, there have been a large number of modelling approaches aimed
at elucidating the most important mechanisms affecting the formation of new capillaries
from parent blood vessels — a process known as angiogenesis. Most studies have focussed
upon the way in which capillary sprouts are initiated and migrate in response to
diffusible chemical stimuli supplied by hypoxic stromal cells and leukocytes in the
contexts of solid tumour...
We consider an ecosystem in which
spiders may be transported by the wind from vineyards into the
surrounding woods and vice versa. The model takes into account
this tranport phenomenon without building space explicitly into
the governing equations. The equilibria of the dynamical system
are analyzed together with their stability, showing that
bifurcations may occur. Then the effects of indiscriminated
spraying to keep pests under control is also investigated via
suitable simulations.
Two main approaches have been considered for modelling the dynamics of the SIS model on
complex metapopulations, i.e, networks of populations connected by migratory flows whose
configurations are described in terms of the connectivity distribution of nodes (patches)
and the conditional probabilities of connections among classes of nodes sharing the same
degree. In the first approach migration and transmission/recovery process alternate
sequentially,...
Tuberculosis (TB) is the leading cause of death among individuals infected with the
hepatitis B virus (HBV). The study of the joint dynamics of HBV and TB present formidable
mathematical challenges due to the fact that the models of transmission are quite
distinct. We formulate and analyze a deterministic mathematical model which incorporates
of the co-dynamics of hepatitis B and tuberculosis. Two sub-models, namely: HBV-only and
TB-only sub-models...
Tumour immunotherapy is aimed at the stimulation of the otherwise inactive immune system to remove, or at least to restrict, the growth of the original tumour and its metastases. The tumour-immune system interactions involve the stimulation of the immune response by tumour antigens, but also the tumour induced death of lymphocytes. A system of two non-linear ordinary differential equations was used to describe the dynamic process of interaction between the immune system and the tumour. Three different...
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1854