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Search Results: 1 - 10 of 462001 matches for " A. Vignaud "
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Potts models in the continuum. Uniqueness and exponential decay in the restricted ensembles
A. De Masi,I. Merola,E. Presutti,Y. Vignaud
Mathematics , 2008, DOI: 10.1007/s10955-008-9603-2
Abstract: In this paper we study a continuum version of the Potts model. Particles are points in R^d, with a spin which may take S possible values, S being at least 3. Particles with different spins repel each other via a Kac pair potential. In mean field, for any inverse temperature there is a value of the chemical potential at which S+1 distinct phases coexist. For each mean field pure phase, we introduce a restricted ensemble which is defined so that the empirical particles densities are close to the mean field values. Then, in the spirit of the Dobrushin Shlosman theory, we get uniqueness and exponential decay of correlations when the range of the interaction is large enough. In a second paper, we will use such a result to implement the Pirogov-Sinai scheme proving coexistence of S+1 extremal DLR measures.
Impaired Skeletal Muscle Repair after Ischemia-Reperfusion Injury in Mice
A. Vignaud,C. Hourde,F. Medja,O. Agbulut,G. Butler-Browne,A. Ferry
Journal of Biomedicine and Biotechnology , 2010, DOI: 10.1155/2010/724914
Abstract: Ischemia/reperfusion (IR) injury can induce skeletal muscle fibre death and subsequent regeneration. By 14 days, absolute and specific maximal forces and fatigue resistance in ischemic/reperfused soleus muscles were still reduced (−89%, −81%, and −75%, resp.) as compared to control muscles (<.05). The decrease of these parameters in ischemic/reperfused muscle was much greater than that of myotoxic injured muscles (−12%, −11%, and −19%; <.05). In addition, at 14 days ischemic/reperfused muscle structure was still abnormal, showing small muscle fibres expressing neonatal myosin heavy chain and large necrotic muscle fibres that were not observed in myotoxin treated muscles. By 56 days, in contrast to myotoxin treated muscles, specific maximal force and muscle weight of the ischemic/reperfused muscles did not fully recover (<.05). This differential recovery between ischemic/reperfused and myotoxin treated muscles was not related to the differences in the initial cell death, loss of satellite cells after injury, expression of growth factors (IGF1, IGF2..), or capillary density in regenerating muscles. In conclusion, our results demonstrate that IR injury in mice induces long term detrimental effects in skeletal muscles and that the recovery following IR injury was delayed for yet unknown reasons as compared to myotoxic injury.
MRI of the lung using hyperpolarized He-3 at very low magnetic field (3 mT)
C. P. Bidinosti,J. Choukeife,G. Tastevin,A. Vignaud,P. -J. Nacher
Physics , 2004,
Abstract: Optical pumping of He-3 produces large (hyper) nuclear-spin polarizations independent of the magnetic resonance imaging (MRI) field strength. This allows lung MRI to be performed at reduced fields with many associated benefits, such as lower tissue susceptibility gradients and decreased power absorption rates. Here we present results of 2D imaging as well as accurate 1D gas diffusion mapping of the human lung using He-3 at very low field (3 mT). Furthermore, measurements of transverse relaxation in zero applied gradient are shown to accurately track pulmonary oxygen partial pressure, opening the way for novel imaging sequences.
Dobrushin Interfaces via Reflection Positivity
Senya Shlosman,Yvon Vignaud
Physics , 2006, DOI: 10.1007/s00220-007-0308-1
Abstract: We study the interfaces separating different phases of 3D systems by means of the Reflection Positivity method. We treat discrete non-linear sigma-models, which exhibit power-law decay of correlations at low temperatures, and we prove the rigidity property of the interface. Our method is applicable to the Ising and Potts models, where it simplifies the derivation of some known results. The method also works for large-entropy systems of continuous spins.
Investigating liquid surfaces down to the nanometer scale using grazing incidence x-ray scattering
C. Fradin,A. Braslau,D. Luzet,M. Alba,C. Gourier,J. Daillant,G. Gruebel,G. Vignaud,J. -F. Legrand,J. Lal J. -M. Petit,F. Rieutord
Physics , 1997, DOI: 10.1016/S0921-4526(98)00255-5
Abstract: Grazing incidence x-ray surface scattering has been used to investigate liquid surfaces down to the molecular scale. The free surface of water is well described by the capillary wave model ( ~ q-2 spectrum) up to wavevectors > 10^8 m^-1. At larger wavevectors near-surface acoustic waves must be taken into account. When the interface is bounded by a surfactant monolayer, it exhibits a bending stiffness and the bending rigidity modulus can be measured. However, bending effects generally cannot be described using the Helfrich Hamiltonian and the characteristic exponent in the roughness power spectrum can smaller than 4. Finally, upon compression, tethered monolayers formed on a subphase containing divalent ions are shown to buckle in the third dimension with a characteristic wavelength on the order of 10^8 m^-1.
Polymorphisms of GSTs in Lung Adenocarcinoma Patients Followed in the Context of a Biobank  [PDF]
Fotis Vlastos, Georgios Hillas, Nektarios Anagnostopoulos, Jean Michel Vignaud, Nadine Martinet, Nikolaos G. Koulouris
Journal of Cancer Therapy (JCT) , 2013, DOI: 10.4236/jct.2013.48A004

Background: Lung Adenocarcinoma (ADC) has been recently associated with distinct molecular changes, leading to the development of molecular-based targeted therapy. The Nancy’s Centre of Biological Resources (“Centre des Ressources Biologiques”, CRB) is an ISO 9001-2000 certified biobank with biological material and follow-up data from lung cancer patients, which collected during the last 20 years. Objective: To estimate and compare the frequency of Glutathionne S-Transferase (GST) polymorphisms in a French population of ADC patients. Methods: A retrospective study was conducted by the CRB between 1988 and 2007: 296 consecutive patients operated upon for ADC and 447 healthy subjects were evaluated. Genomic DNA was obtained from peripheral blood samples collected in EDTA tubes. The DNA was extracted using proteinase K digestion and phenol: chloroform purification. The GST polymorphisms were studied with duplex SYBR Green q PCR using specific primers and results being read on melt curves. Results: Two GST classes were monitored during this research. The Mu class GST (GSTM) and the Theta class GST (GSTT) members. We studied the incidence of each genotype, as well as the GSTMT (combined Mu and Theta class) and null genotype in ADC and control patients. ADC patients had a higher incidence of

Microsatellite Analyses of Blacktip Reef Sharks (Carcharhinus melanopterus) in a Fragmented Environment Show Structured Clusters
Thomas Vignaud, Eric Clua, Johann Mourier, Jeffrey Maynard, Serge Planes
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061067
Abstract: The population dynamics of shark species are generally poorly described because highly mobile marine life is challenging to investigate. Here we investigate the genetic population structure of the blacktip reef shark (Carcharhinus melanopterus) in French Polynesia. Five demes were sampled from five islands with different inter-island distances (50–1500 km). Whether dispersal occurs between islands frequently enough to prevent moderate genetic structure is unknown. We used 11 microsatellites loci from 165 individuals and a strong genetic structure was found among demes with both F-statistics and Bayesian approaches. This differentiation is correlated with the geographic distance between islands. It is likely that the genetic structure seen is the result of all or some combination of the following: low gene flow, time since divergence, small effective population sizes, and the standard issues with the extent to which mutation models actually fit reality. We suggest low levels of gene flow as at least a partial explanation of the level of genetic structure seen among the sampled blacktip demes. This explanation is consistent with the ecological traits of blacktip reef sharks, and that the suitable habitat for blacktips in French Polynesia is highly fragmented. Evidence for spatial genetic structure of the blacktip demes we studied highlights that similar species may have populations with as yet undetected or underestimated structure. Shark biology and the market for their fins make them highly vulnerable and many species are in rapid decline. Our results add weight to the case that total bans on shark fishing are a better conservation approach for sharks than marine protected area networks.
Coexistence of ordered and disordered phases in Potts models in the continuum
Anna De Masi,Immacolata Merola,Errico Presutti,Yvon Vignaud
Mathematics , 2008, DOI: 10.1007/s10955-008-9677-x
Abstract: This is the second of two papers on a continuum version of the Potts model, where particles are points in $\mathbb R^d$, $d\ge 2$, with a spin which may take $S\ge 3$ possible values. Particles with different spins repel each other via a Kac pair potential of range $\ga^{-1}$, $\ga>0$. In this paper we prove phase transition, namely we prove that if the scaling parameter of the Kac potential is suitably small, given any temperature there is a value of the chemical potential such that at the given temperature and chemical potential there exist $S+1$ mutually distinct DLR measures.
Facial Orientation and Facial Shape in Extant Great Apes: A Geometric Morphometric Analysis of Covariation
Dimitri Neaux, Franck Guy, Emmanuel Gilissen, Walter Coudyzer, Patrick Vignaud, Stéphane Ducrocq
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0057026
Abstract: The organization of the bony face is complex, its morphology being influenced in part by the rest of the cranium. Characterizing the facial morphological variation and craniofacial covariation patterns in extant hominids is fundamental to the understanding of their evolutionary history. Numerous studies on hominid facial shape have proposed hypotheses concerning the relationship between the anterior facial shape, facial block orientation and basicranial flexion. In this study we test these hypotheses in a sample of adult specimens belonging to three extant hominid genera (Homo, Pan and Gorilla). Intraspecific variation and covariation patterns are analyzed using geometric morphometric methods and multivariate statistics, such as partial least squared on three-dimensional landmarks coordinates. Our results indicate significant intraspecific covariation between facial shape, facial block orientation and basicranial flexion. Hominids share similar characteristics in the relationship between anterior facial shape and facial block orientation. Modern humans exhibit a specific pattern in the covariation between anterior facial shape and basicranial flexion. This peculiar feature underscores the role of modern humans' highly-flexed basicranium in the overall integration of the cranium. Furthermore, our results are consistent with the hypothesis of a relationship between the reduction of the value of the cranial base angle and a downward rotation of the facial block in modern humans, and to a lesser extent in chimpanzees.
Chondroid Chordoma and Nasal Adenocarcinoma: An Exceptional Association
Patrice Gallet,Nathalie Marcon,Thomas Georgel,Jean-Marie Vignaud,Cécile Parietti-Winkler,Roger Jankowski
Case Reports in Oncological Medicine , 2012, DOI: 10.1155/2012/861217
Abstract: Collision tumors are exceptional, associating two independent tumoral contingents. We report a case of an association of two rare tumors: sinonasal adenocarcinoma and chondroid chordoma. Initially, only adenocarcinoma was diagnosed. The treatment consisted of endoscopic endonasal surgery followed by conventional radiotherapy. After 18 months, a local recurrence was diagnosed after a facial trauma, but the true histology was difficult to assess. The tumor was dual, associating adenocarcinoma and chondroid chordoma, with atypical localization in the ethmoid. Further evolution was particularly aggressive. We discuss the key points of this observation.
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