4,436 research outputs found
Changing the branching mechanism of a continuous state branching process using immigration
We construct a continuous state branching process with immigration (CBI)
whose immigration depends on the CBI itself and we recover a continuous state
branching process (CB). This provides a dual construction of the pruning at
nodes of CB introduced by the authors in a previous paper. This construction is
a natural way to model neutral mutation. Using exponential formula, we compute
the probability of extinction of the original type population in a critical or
sub-critical quadratic branching, conditionally on the non extinction of the
total population
Asymptotics for the small fragments of the fragmentation at nodes
We consider the fragmentation at nodes of the L\'{e}vy continuous random tree
introduced in a previous paper. In this framework we compute the asymptotic for
the number of small fragments at time . This limit is increasing in
and discontinuous. In the -stable case the fragmentation is
self-similar with index , with and the results are
close to those Bertoin obtained for general self-similar fragmentations but
with an additional assumtion which is not fulfilled here
The forest associated with the record process on a L\'evy tree
We perform a pruning procedure on a L\'evy tree and instead of throwing away
the removed sub-tree, we regraft it on a given branch (not related to the
L\'evy tree). We prove that the tree constructed by regrafting is distributed
as the original L\'evy tree, generalizing a result where only Aldous's tree is
considered. As a consequence, we obtain that the quantity which represents in
some sense the number of cuts needed to isolate the root of the tree, is
distributed as the height of a leaf picked at random in the L\'evy tree
Record process on the Continuum Random Tree
By considering a continuous pruning procedure on Aldous's Brownian tree, we
construct a random variable which is distributed, conditionally given
the tree, according to the probability law introduced by Janson as the limit
distribution of the number of cuts needed to isolate the root in a critical
Galton-Watson tree. We also prove that this random variable can be obtained as
the a.s. limit of the number of cuts needed to cut down the subtree of the
continuum tree spanned by leaves
A construction of a -coalescent via the pruning of Binary Trees
Considering a random binary tree with labelled leaves, we use a pruning
procedure on this tree in order to construct a -coalescent
process. We also use the continuous analogue of this construction, i.e. a
pruning procedure on Aldous's continuum random tree, to construct a continuous
state space process that has the same structure as the -coalescent
process up to some time change. These two constructions unable us to obtain
results on the coalescent process such as the asymptotics on the number of
coalescent events or the law of the blocks involved in the last coalescent
event
Compensating Differentials and Fringe Benefits: Evidence from the Medical Expenditure Panel Survey 1997-2004
In this paper, we revisited the question of the existence of a tradeoff between wages and health insurance by extending previous work in the following way: 1) we exploit richer information on health insurance in terms of whether the worker holds health insurance or whether it is offered at the firm but he/she does not hold it, 2) we analyze possible combinations of health insurance with other fringe benefits (retirement, sick leave and paid vacation), 3) we include information on workers health (self-reported) as a determinants of workers wage and mobility decision, and 4) we use an econometric framework and GMM estimations which allow us to treat the issues of endogenous choice of benefits and mobility into benefits sectors encountered in the literature and estimate the extent of worker selection into jobs with/without benefits based on unobserved individual-specific traits, skills and health status.
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