915 research outputs found
Geotraceability: an innovative concept to enhance conventional traceability in the agri-food chain
With the globalization of trade, people have become enlightened and demanding consumers as regards the origin of their food and the environment in which it is produced. The concept of geotraceability described in this article responds to that requirement by combining geographical information with conventional traceability data. The inclusion of geographical information relating to the environment of the production plots is based not only on exploiting some functionalities of spatial analysis tools that exist in geographical information systems (GIS) but also on developing specific tools such as a geoidentifier and geoindicators. This article also describes the characteristics and methods of implementing a geographical information management system linked with traceability information. Lastly, the potential for using geotraceability systems in supply chains is analyzed, in particular for consumer warnings in cases of food crisis and assistance for certification of differentiated quality agricultural products
The stochastic limit in the analysis of the open BCS model
In this paper we show how the perturbative procedure known as {\em stochastic
limit} may be useful in the analysis of the Open BCS model discussed by Buffet
and Martin as a spin system interacting with a fermionic reservoir. In
particular we show how the same values of the critical temperature and of the
order parameters can be found with a significantly simpler approach
The Approximating Hamiltonian Method for the Imperfect Boson Gas
The pressure for the Imperfect (Mean Field) Boson gas can be derived in
several ways. The aim of the present note is to provide a new method based on
the Approximating Hamiltonian argument which is extremely simple and very
general.Comment: 7 page
Annealed lower tails for the energy of a polymer
We consider the energy of a randomly charged polymer. We assume that only
charges on the same site interact pairwise. We study the lower tails of the
energy, when averaged over both randomness, in dimension three or more. As a
corollary, we obtain the correct temperature-scale for the Gibbs measure.Comment: 27 page
Study of a high spatial resolution 10B-based thermal neutron detector for application in neutron reflectometry: the Multi-Blade prototype
Although for large area detectors it is crucial to find an alternative to
detect thermal neutrons because of the 3He shortage, this is not the case for
small area detectors. Neutron scattering science is still growing its
instruments' power and the neutron flux a detector must tolerate is increasing.
For small area detectors the main effort is to expand the detectors'
performances. At Institut Laue-Langevin (ILL) we developed the Multi-Blade
detector which wants to increase the spatial resolution of 3He-based detectors
for high flux applications. We developed a high spatial resolution prototype
suitable for neutron reflectometry instruments. It exploits solid 10B-films
employed in a proportional gas chamber. Two prototypes have been constructed at
ILL and the results obtained on our monochromatic test beam line are presented
here
Proof of Bose-Einstein Condensation for Interacting Gases with a One-Particle Spectral Gap
Using a specially tuned mean-field Bose gas as a reference system, we
establish a positive lower bound on the condensate density for continuous Bose
systems with superstable two-body interactions and a finite gap in the
one-particle excitations spectrum, i.e. we prove for the first time standard
homogeneous Bose-Einstein condensation for such interacting systems
Equivalence of Bose-Einstein condensation and symmetry breaking
Based on a classic paper by Ginibre [Commun. Math. Phys. {\bf 8} 26 (1968)]
it is shown that whenever Bogoliubov's approximation, that is, the replacement
of a_0 and a_0^* by complex numbers in the Hamiltonian, asymptotically yields
the right pressure, it also implies the asymptotic equality of ||^2/V and
/V in symmetry breaking fields, irrespective of the existence or
absence of Bose-Einstein condensation. Because the former was proved by Ginibre
to hold for absolutely integrable superstable pair interactions, the latter is
equally valid in this case. Apart from Ginibre's work, our proof uses only a
simple convexity inequality due to Griffiths.Comment: An error in my summary of previous results (the definition of F') is
corrected. The correction is to be done also in the PR
Geodynamo alpha-effect derived from box simulations of rotating magnetoconvection
The equations for fully compressible rotating magnetoconvection are
numerically solved in a Cartesian box assuming conditions roughly suitable for
the geodynamo. The mean electromotive force describing the generation of mean
magnetic flux by convective turbulence in the rotating fluid is directly
calculated from the simulations, and the corresponding alpha-coefficients are
derived. Due to the very weak density stratification the alpha-effect changes
its sign in the middle of the box. It is positive at the top and negative at
the bottom of the convection zone. For strong magnetic fields we also find a
clear downward advection of the mean magnetic field. Both of the simulated
effects have been predicted by quasi-linear computations (Soward, 1979;
Kitchatinov and Ruediger, 1992). Finally, the possible connection of the
obtained profiles of the EMF with mean-field models of oscillating
alpha^2-dynamos is discussed.Comment: 17 pages, 9 figures, submitted to Phys. Earth Planet. Inte
The Canonical Perfect Bose Gas in Casimir Boxes
We study the problem of Bose-Einstein condensation in the perfect Bose gas in
the canonical ensemble, in anisotropically dilated rectangular parallelpipeds
(Casimir boxes). We prove that in the canonical ensemble for these anisotropic
boxes there is the same type of generalized Bose-Einstein condensation as in
the grand-canonical ensemble for the equivalent geometry. However the amount of
condensate in the individual states is different in some cases and so are the
fluctuations.Comment: 23 page
Association entre la dégénérescence maculaire liée à l’âge et les parodontites
Purpose: To evaluate the association between age-related macular degeneration (AMD) and periodontal disease, two frequent conditions in the elderly, with some risk factors in common. Methods: Single center, pilot, case-control study performed in a center specialized in the diagnosis and management of AMD. Periodontal status was evaluated in 43 AMD patients and 19 controls. Fundus examination and a complete periodontal examination were performed in all subjects. Results: AMD patients have a greater percentage of 3–4 mm clinical attachment loss compared to controls (47% vs. 38%, [P = 0.039]). However, no significant difference was found between the groups with regard to the prevalence of severe periodontitis. Conclusions: These results suggest an association between AMD and attachment loss characteristic of periodontal disease and support the need for larger prospective studies to elucidate the relationships between these 2 highly prevalent and potentially severe diseases
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