Clément Dombry
Phenotypic diversity and population growth in fluctuating environment: a MBPRE approach.
Tue, 12/08/2009 - 16:01 — SomNambulAuthors: Clément Dombry, Vincent Bansaye, Christian Mazza
Subjects: Probability
AbstractOrganisms adapt to fluctuating environments by regulating their dynamics, and
by adjusting their phenotypes to environmental changes. We model population
growth using multitype branching processes in random environments, where the
offspring distribution of some organism having trait $t\in\cT$ in environment
$e\in\cE$ is given by some (fixed) distribution $\Upsilon_{t,e}$ on $\bbN$.
Then, the phenotypes are attributed using a distribution (strategy) $\pi_{t,e}$
on the trait space $\cT$.Extremal shot noises, heavy tails and max-stable random fields.
Mon, 08/31/2009 - 17:16 — SomNambulAuthors: Clément Dombry
Subjects: Probability
AbstractExtremal shot noises naturally appear in extreme value theory as a model for
spatial extremes and serve as basic models for annual maxima of rainfall or for
coverage field in telecommunication. In this work, we examine their properties
such as boundedness, regularity, ergodicity ... Connexions with max-stable
random fields are established: we prove a limit theorem when the distribution
of the weights is heavy tailed and the intensity of points goes to infinity. We
use a point process approach strongly connected to the Peak Over Threshold
method used by hydrologists.Rescaled weighted random balls models and stable self-similar random fields.
Thu, 08/27/2009 - 13:23 — SomNambulAuthors: Jean-Christophe Breton, Clément Dombry
Subjects: Probability
AbstractWe consider weighted random balls in $\real^d$ distributed according to a
random Poisson measure with heavy-tailed intensity and study the asymptotic
behaviour of the total weight of some configurations in $\real^d$. This
procedure amounts to be very rich and several regimes appear in the limit,
depending on the intensity of the balls, the zooming factor, the tail
parameters of the radii and of the weights. Statistical properties of the limit
fields are also evidenced, such as isotropy, self-similarity or dependence.Rescaled weighted random balls models and stable self-similar random fields.
Thu, 08/27/2009 - 13:23 — SomNambulAuthors: Jean-Christophe Breton, Clément Dombry
Subjects: Probability
AbstractWe consider weighted random balls in $\real^d$ distributed according to a
random Poisson measure with heavy-tailed intensity and study the asymptotic
behaviour of the total weight of some configurations in $\real^d$. This
procedure amounts to be very rich and several regimes appear in the limit,
depending on the intensity of the balls, the zooming factor, the tail
parameters of the radii and of the weights. Statistical properties of the limit
fields are also evidenced, such as isotropy, self-similarity or dependence.
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