574 research outputs found
Étude de la co-exposition aux contraintes physiques et aux produits chimiques neurotoxiques chez les salariés des Pays de la Loire
In many working environments, employees face important biomechanical constraints, heavy physical demands and/or shift work. However, epidemiological surveillance has rarely addressed the issue of co-exposure to neurotoxic chemicals and biomechanical risk factors for musculoskeletal disorders that may affect peripheral nerves. Data from the regional sample of the SUMER 2003 survey were used to study these professional co-exposure phenomena in the Pays de la Loire region. After raking ratio adjustment of the regional survey data (i.e. 916,361 employees after extrapolation), descriptive analyses were carried out separately for men and women and showed that 43% of men and 27% of women were exposed to repetitive tasks and/or vibrating tools and/or cold environment, and 30% of men and 5% of women were exposed to at least one neurotoxic chemical. In men, co-exposure to neurotoxic chemicals and biomechanical constraints was common, especially in the construction and metal processing sectors. This study shows that co-exposure to biomechanical and chemical factors which may cause peripheral neuropathies focuses on the same occupational categories
Universal Relationship Between Giant Magnetoresistance and Anisotropic Magnetoresistance in Spin Valve Multilayers
We measure the giant magnetoresistance (GMR) with the current both parallel
and perpendicular to the direction of the magnetization in the ferromagnetic
(FM) layers and thus probe the anisotropy of the effective mean free paths for
the spin-up and spin-down electrons, seen in the anisotropic magnetoresistance.
We find that the difference of the GMR in the two configurations, when
expressed in terms of the sheet conductance, displays a nearly universal
behavior as a function of GMR. On interpreting the results within the Boltzmann
transport formalism we demonstrate the importance of bulk scattering for GMR.Comment: REVTEX, 2 figure
Chemosensory Profile of South Tyrolean Pinot Blanc Wines: A Multivariate Regression Approach
Publishe
Magnon dispersion and thermodynamics in CsNiF_3
We present an accurate transfer matrix renormalization group calculation of
the thermodynamics in a quantum spin-1 planar ferromagnetic chain. We also
calculate the field dependence of the magnon gap and confirm the accuracy of
the magnon dispersion derived earlier through an 1/n expansion. We are thus
able to examine the validity of a number of previous calculations and further
analyze a wide range of experiments on CsNiF_3 concerning the magnon
dispersion, magnetization, susceptibility, and specific heat. Although it is
not possible to account for all data with a single set of parameters, the
overall qualitative agreement is good and the remaining discrepancies may
reflect departure from ideal quasi-one-dimensional model behavior. Finally, we
present some indirect evidence to the effect that the popular interpretation of
the excess specific heat in terms of sine-Gordon solitons may not be
appropriate.Comment: 9 pages 10 figure
Phenomenological model for the remanent magnetization of dilute quasi-one-dimensional antiferromagnets
We present a phenomenological model for the remanent magnetization at low
temperatures in the quasi-one-dimensional dilute antiferromagnets
CH_{3}NH_{3}Mn_{1-x}Cd_{x} Cl_{3}\cdot 2H_{2}O and
(CH_{3})_{2}NH_{2}Mn_{1-x}Cd_{x}Cl_{3}\cdot 2H_{2}O. The model assumes the
existence of uncompensated magnetic moments induced in the odd-sized segments
generated along the Mn(^{2+}) chains upon dilution. These moments are further
assumed to correlate ferromagnetically after removal of a cooling field. Using
a (mean-field) linear-chain approximation and reasonable set of model
parameters, we are able to reproduce the approximate linear temperature
dependence observed for the remanent magnetization in the real compounds.Comment: 5 pages, 2 figures; final version to appear in Physical Review
The Origin of Intraspecific Variation of Virulence in an Eukaryotic Immune Suppressive Parasite
Occurrence of intraspecific variation in parasite virulence, a prerequisite for coevolution of hosts and parasites, has largely been reported. However, surprisingly little is known of the molecular bases of this variation in eukaryotic parasites, with the exception of the antigenic variation used by immune-evading parasites of mammals. The present work aims to address this question in immune suppressive eukaryotic parasites. In Leptopilina boulardi, a parasitic wasp of Drosophila melanogaster, well-defined virulent and avirulent strains have been characterized. The success of virulent females is due to a major immune suppressive factor, LbGAP, a RacGAP protein present in the venom and injected into the host at oviposition. Here, we show that an homologous protein, named LbGAPy, is present in the venom of the avirulent strain. We then question whether the difference in virulence between strains originates from qualitative or quantitative differences in LbGAP and LbGAPy proteins. Results show that the recombinant LbGAPy protein has an in vitro GAP activity equivalent to that of recombinant LbGAP and similarly targets Drosophila Rac1 and Rac2 GTPases. In contrast, a much higher level of both mRNA and protein is found in venom-producing tissues of virulent parasitoids. The F1 offspring between virulent and avirulent strains show an intermediate level of LbGAP in their venom but a full success of parasitism. Interestingly, they express almost exclusively the virulent LbGAP allele in venom-producing tissues. Altogether, our results demonstrate that the major virulence factor in the wasp L. boulardi differs only quantitatively between virulent and avirulent strains, and suggest the existence of a threshold effect of this molecule on parasitoid virulence. We propose that regulation of gene expression might be a major mechanism at the origin of intraspecific variation of virulence in immune suppressive eukaryotic parasites. Understanding this variation would improve our knowledge of the mechanisms of transcriptional evolution currently under active investigation
Remove Noise in Video with 3D Topological Maps
International audienceIn this paper we present a new method for foreground masks denoising in videos. Our main idea is to consider videos as 3D images and to deal with regions in these images. Denoising is thus simply achieved by merging foreground regions corresponding to noise with background regions. In this framework, the main question is the definition of a cri-terion allowing to decide if a region corresponds to noise or not. Thanks to our complete cellular description of 3D images, we can propose an advanced criterion based on Betti numbers, a topological invariant. Our results show the interest of our approach which gives better results than previous methods
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