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Mahe G.,Gonda Vascular Center | Mahe G.,niversite Nantes Angers Le Mans | Liedl D.A.,Gonda Vascular Center | McCarter C.,Gonda Vascular Center | And 5 more authors.
Journal of Vascular Surgery | Year: 2014

Objective This study was conducted to determine the sensitivity and specificity of laser Doppler flowmetry (LDF) measurements for digital obstructive arterial disease (DOAD) using angiography as the reference standard and to compare the accuracy of different classical tests used to assess DOAD. Diagnosis of vascular abnormalities at the digital level is challenging. Angiography is the gold standard for assessment of DOAD but is invasive and expensive to perform. Methods We performed a retrospective analysis of consecutive patients referred at Mayo Clinic (Rochester, Minn) for upper extremity arterial assessment during a 27-month period. Finger-brachial index, skin blood flow (in arbitrary units [a.u.]), and skin temperature (in degrees Celsius) were recorded in each digit on the pulp at baseline and after a thermal challenge test (hand placed in a thermal box at 47.0 C for 15 minutes). Angiogram analysis was blinded and performed by a radiologist using a vascularization scale ranging from 0 (no vessel) to 4 (normal). The receiver operating characteristic curve was used to define a specific cutoff point to detect DOAD. Twenty-two patients had LDF measurements and complete angiograms. Results A total of 185 digits were analyzed because some patients had only analysis of one hand. The best area under the curve (AUC) was 0.98 (range, 0.94-0.99) for postwarming skin blood flow, with a cutoff point of ≤206 a.u. This AUC was statistically different from AUCs of all the other tests (P <.01). Sensitivity and specificity were 93% (95% confidence interval, 85%-97%) and 96% (95% confidence interval, 90%-99%), respectively. Conclusions LDF combined with a thermal challenge is highly accurate, safe, and noninvasive means to detect DOAD. © 2014 by the Society for Vascular Surgery. Source


Membre J.-M.,French National Institute for Agricultural Research | Membre J.-M.,niversite Nantes Angers Le Mans | Guillou S.,niversite Nantes Angers Le Mans
Current Opinion in Food Science | Year: 2016

Microbiological Risk Assessment (MRA) is a structured process for determining the public health risk associated with foodborne pathogens. In recent years, there has been a strong tendency in providing food safety decisions based upon quantitative assessment. Especially, variability and uncertainty inherent to biological processes have been integrated in food safety management through the use of powerful statistical and probabilistic techniques. Besides, recent developments in omic technologies may fill knowledge gaps on strain diversity and physiological variability, and, open new perspectives to refine hazard identification. Last, to satisfy the societal demand for balanced recommendations on food, MRA could be, in a near future, embedded into a more comprehensive assessment including chemical and nutritional issues, but also, cost and sustainability considerations. © 2016 Elsevier Ltd. Source


Dagnas S.P.,niversite Nantes Angers Le Mans | Membre J.-M.,niversite Nantes Angers Le Mans | Membre J.-M.,French National Institute for Agricultural Research
Journal of Food Protection | Year: 2013

This article is a review of how to quantify mold spoilage and consequently shelf life of a food product. Mold spoilage results from having a product contaminated with fungal spores that germinate and form a visible mycelium before the end of the shelf life. The spoilage can be then expressed as the combination of the probability of having a product contaminated and the probability of mold growth (germination and proliferation) up to a visible mycelium before the end of the shelf life. For products packed before being distributed to the retailers, the probability of having a product contaminated is a function of factors strictly linked to the factory design, process, and environment. The in-factory fungal contamination of a product might be controlled by good manufacturing hygiene practices and reduced by particular processing practices such as an adequate air-renewal system. To determine the probability of mold growth, both germination and mycelium proliferation can be mathematically described by primary models. When mold contamination on the product is scarce, the spores are spread on the product and more than a few spores are unlikely to be found at the same spot. In such a case, models applicable for a single spore should be used. Secondary models can be used to describe the effect of intrinsic and extrinsic factors on either the germination or proliferation of molds. Several polynomial models and gamma-type models quantifying the effect of water activity and temperature on mold growth are available. To a lesser extent, the effect of pH, ethanol, heat treatment, addition of preservatives, and modified atmospheres on mold growth also have been quantified. However, mold species variability has not yet been properly addressed, and only a few secondary models have been validated for food products. Once the probability of having mold spoilage is calculated for various shelf lives and product formulations, the model can be implemented as part of a risk management decision tool. Copyright ©, International Association for Food Protection. Source


Nasser H.,niversite Nantes Angers Le Mans | Chabot A.,niversite Nantes Angers Le Mans
Civil-Comp Proceedings | Year: 2015

This paper presents an engineering tool for the rapid analysis of the mechanical fields in cracked pavements. The pavement structure is reduced to three elastic and homogeneous equivalent layers resting on a soil. The soil is modelled by one layer, named the shear layer, connected to Winkler's springs in order to ensure the transfer of shear stresses between the pavement structure and the springs. The whole fourlayer system (three pavement layers connected to the shear layer) is modelled using a simplified model (M4-5n) developed for the analysis of delamination in composite materials. For the case of two-dimensional plane strain, a system of twelve equations is written analytically. These second order differential equations are solved by a finite difference method (Newmark). In the case of a pavement containing a vertical cracking through one layer, the half-analytical solutions are obtained in less than one second of CPU. This tool, called M4-5nW, thus allows parametric studies such as the distribution of mechanical fields (especially interface stresses) as a function of the load position more or less distant from the vertical crack. This new modelling shows its effectiveness compared to the use of a conventional finite element code. © Civil-Comp Press, 2015. Source


Dagnas S.,niversite Nantes Angers Le Mans | Onno B.,niversite Nantes Angers Le Mans | Membre J.-M.,niversite Nantes Angers Le Mans | Membre J.-M.,French National Institute for Agricultural Research
International Journal of Food Microbiology | Year: 2014

The objective of this study was to quantify the effect of water activity, pH and storage temperature on the growth of Eurotium repens, Aspergillus niger and Penicillium corylophilum, isolated from spoiled bakery products. Moreover, the behaviors of these three mold species were compared to assess whether a general modeling framework may be set and re-used in future research on bakery spoilage molds. The mold growth was modeled by building two distinct Gamma-type secondary models: one on the lag time for growth and another one on the radial growth rate. A set of 428 experimental growth curves was generated. The effect of temperature (15-35. °C), water activity (0.80-0.98) and pH (3-7) was assessed. Results showed that it was not possible to apply the same set of secondary model equations to the three mold species given that the growth rate varied significantly with the factors pH and water activity. In contrast, the temperature effect on both growth rate and lag time of the three mold species was described by the same equation. The equation structure and model parameter values of the Gamma models were also compared per mold species to assess whether a relationship between lag time and growth rate existed. There was no correlation between the two growth responses for E. repens, but a slight one for A. niger and P. corylophilum. These findings will help in determining bakery product shelf-life and guiding future work in the predictive mycology field. © 2014 Elsevier B.V. Source

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