124,686 research outputs found
Equilibrium statistical mechanics and energy partition for the shallow water model
The aim of this paper is to use large deviation theory in order to compute
the entropy of macrostates for the microcanonical measure of the shallow water
system. The main prediction of this full statistical mechanics computation is
the energy partition between a large scale vortical flow and small scale
fluctuations related to inertia-gravity waves. We introduce for that purpose a
discretized model of the continuous shallow water system, and compute the
corresponding statistical equilibria. We argue that microcanonical equilibrium
states of the discretized model in the continuous limit are equilibrium states
of the actual shallow water system. We show that the presence of small scale
fluctuations selects a subclass of equilibria among the states that were
previously computed by phenomenological approaches that were neglecting such
fluctuations. In the limit of weak height fluctuations, the equilibrium state
can be interpreted as two subsystems in thermal contact: one subsystem
corresponds to the large scale vortical flow, the other subsystem corresponds
to small scale height and velocity fluctuations. It is shown that either a
non-zero circulation or rotation and bottom topography are required to sustain
a non-zero large scale flow at equilibrium. Explicit computation of the
equilibria and their energy partition is presented in the quasi-geostrophic
limit for the energy-enstrophy ensemble. The possible role of small scale
dissipation and shocks is discussed. A geophysical application to the Zapiola
anticyclone is presented.Comment: Journal of Statistical Physics, Springer Verlag, 201
Elastic contact to nearly incompressible coatings -- Stiffness enhancement and elastic pile-up
We have recently proposed an efficient computation method for the
frictionless linear elastic axisymmetric contact of coated bodies [A. Perriot
and E. Barthel, J. Mat. Res. 19 (2004) 600]. Here we give a brief description
of the approach. We also discuss implications of the results for the
instrumented indentation data analysis of coated materials. Emphasis is laid on
incompressible or nearly incompressible materials (Poisson ratio ): we
show that the contact stiffness rises much more steeply with contact radius
than for more compressible materials and significant elastic pile-up is
evidenced. In addition the dependence of the penetration upon contact radius
increasingly deviates from the homogeneous reference case when the Poisson
ratio increases. As a result, this algorithm may be helpful in instrumented
indentation data analysis on soft and nearly incompressible layers
A dynamical approach to von Neumann dimension
Let G be an amenable group and V be a finite dimensional vector space. Gromov
pointed out that the von Neumann dimension of linear subspaces of l^2(G;V)
(with respect to G) can be obtained by looking at a growth factor for a
dynamical (pseudo-)distance. This dynamical point of view (reminiscent of
metric entropy) does not requires a Hilbertian structure. It is used in this
article to associate to a -invariant linear subspaces Y of l^p(G;V) a
real positive number dim_{l^p} Y (which is the von Neumann dimension when p=2).
By analogy with von Neumann dimension, the properties of this quantity are
explored to conclude that there can be no injective G-equivariant linear map of
finite-type from l^p(G;V) -> l^p(G; V') if dim V > dim V'. A generalization of
the Ornstein-Weiss lemma is developed along the way.Comment: 23 pages. Mistake corrected in statement of P
Case study report The view of the EU cultural and science diplomacy from Egypt. EL-CSID Working Paper Issue 2018/12 • April 2018
As a reminder of the framework of this study, it is worth mentioning, even in general terms, a few
schemes and figures.
A EU-Egypt Association Agreement (2004) and a EU-Egypt Partnership (2017) have been guiding the
relationship between the European Union and the Arab Republic of Egypt, which was maintained
throughout all the recent historical events and mishaps of this big country.
EU assistance to Egypt under the European Neighbourhood and Partnership Instrument (ENPI) for
2007-2013 was over 1 billion €. Under the Single Support Framework for the period 2014-2016 a total
amount of 320 million € in EU grants were committed by the EU. For the period 2014-2020, the
European Neighbourhood Instrument (ENI) is the main financial instrument for EU cooperation with
Egypt. A “Memorandum of Understanding regarding the EU's Single Support Framework 2017-2020”
was signed with Egypt (for an amount of 500 million €), defining priority sectors, amongst which
economic modernisation, energy and environment, having been consensually determined by both
parties.
The “Euro-Mediterranean agreement establishing an association between the European communities
and their member states and the Arab Republic of Egypt” (2004) already included some articles about
culture, science and innovation1
Molecular epidemiological studies of Campylobacter isolated from different sources in New Zealand between 2005 and 2015 : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Manawatu, New Zealand
Campylobacteriosis is one of the most important food-borne diseases worldwide, and a
significant health burden in New Zealand. C. jejuni is the predominant species
worldwide, accounting for approximately 90% of human cases, followed by C. coli.
The first study evaluated whether the time elapsing from sampling to culture has an
impact on the recovery rate of Campylobacter, and explored whether some sequence
types are more likely than others to be missed due to delayed culture. The study
revealed that, whereas delayed culture may affect the recovery rate of Campylobacter,
there was no evidence of a bias due to specific sequence types being under detected.
The second study aimed to analyse the differences in the Campylobacter viable counts
and in population genetic structure between chicken drumsticks and whole carcass meat
for retail sale. The results indicate that the Campylobacter population genetic structure
did not differ between the two types of retail chicken meat. However, the difference in
Campylobacter viable counts suggest that consumption of different chicken meat
products may pose different risks of campylobacteriosis associated with an exposure to
different infection doses.
In the third study, we genotyped C. coli isolates collected from different sources
between 2005 and 2014, to study their population structure and estimate the
contribution of each source to the burden of human C. coli disease. Modelling indicated
ruminants and poultry as the main sources of C. coli infection.
The fourth study aimed to genotype C. jejuni isolates collected between 2005 and 2015
from different sources, to assess changes in the molecular epidemiology of C. jejuni
following the food safety interventions implemented by the New Zealand poultry
industry in 2007/2008. Modelling indicated that chicken meat from ‘Supplier A’ was
the main source of C. jejuni human infection before the interventions; but after the
interventions, ruminants became the main source of infection, followed by chicken meat
from Supplier A.
This thesis has made us aware of the aetiology of C. coli infections and the change in
the attribution of C. jejuni infections. These findings should be used in developing
further strategies to reduce the total burden of human campylobacteriosis
Estimating the geometric median in Hilbert spaces with stochastic gradient algorithms: and almost sure rates of convergence
The geometric median, also called -median, is often used in robust
statistics. Moreover, it is more and more usual to deal with large samples
taking values in high dimensional spaces. In this context, a fast recursive
estimator has been introduced by Cardot, Cenac and Zitt. This work aims at
studying more precisely the asymptotic behavior of the estimators of the
geometric median based on such non linear stochastic gradient algorithms. The
rates of convergence as well as almost sure rates of convergence of
these estimators are derived in general separable Hilbert spaces. Moreover, the
optimal rate of convergence in quadratic mean of the averaged algorithm is also
given
Comment on "Spontaneous collapse: A solution to the measurement problem and a source of the decay in mesonic systems"
In a recent article [Phys. Rev. A 94, 052128 (2016)], the authors compute the
predictions of two collapse models on the transition probabilities of neutral
mesons. Notably, they claim to find an influence on the decay rates and attempt
to prove that a new parameter is required to fully characterize the
noise of standard collapse models. These two claims are incorrect and motivated
by flawed computations. This comment derives the correct transition
probabilities exactly from the master equation, explains how they could be
computed perturbatively in a safe way and finally shows where the main mistake
of the authors of the original article was made.Comment: 4 page
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