Ripening conditions: A tool for the control of Listeria monocytogenes in uncooked pressed type cheese

The effect of ripening conditions (two temperatures, 9 °C and 13 °C, and two relative humidities 93% and 97%) on the growth of Listeria monocytogenes and other microbial populations was evaluated in the cores and rinds of uncooked pressed type cheeses prepared with pasteurised milk and inoculated either with Streptococcus thermophilus only or with an anti-listerial consortium. Regardless of temperature and relative humidity (RH), inhibition by the anti-listerial consortium was stronger in the cheese cores than in the rinds. Temperature had no significant effect on L. monocytogenes counts in cores or rinds. However, at the beginning of ripening in the consortium cheese, L. monocytogenes growth was more strongly inhibited at 13 °C than at 9 °C. Regardless of inoculation type and ripening temperature, counts of L. monocytogenes were significantly lower in the cores and rinds of cheeses ripened at 93% than at 97% RH. Lactobacilli counts were higher at 13 °C than at 9 °C and at 93% than at 97% RH. Lactobacilli can help to inhibit L. monocytogenes by catabolising galactose and producing lactate. Further investigations will be needed to evaluate the effect of ripening at 13 °C and 93% RH on the sensorial properties of cheese.     

Identification of asymmetric constitutive laws at high temperature based on Digital Image Correlation

The mechanical characterization of ceramics can be very challenging. Depending on their composition and fabrication process, ceramic materials may exhibit at room temperature different types of mechanical behaviours, ranging from linear elastic to quasi-brittle, like rocks, concrete or plasters. At elevated temperature, they may present a non-linear behaviour, due for instance to the presence of a vitreous phase. However, estimating the evolution of their behaviour from room temperature to elevated temperature is a challenging topic, especially when there is an asymmetry between tension and compression. A methodology based on Digital Image Correlation is presented in this paper where four point bending tests are analysed for temperatures ranging from 25 °C to 900 °C. For a ceramic mainly made of aluminium titanate, the evolution of an asymmetric constitutive law is identified with a strong link with microstructural observations using SEM images.     

Object exploration and reactions to spatial and nonspatial changes in hooded rats following damage to parietal cortex or hippocampal formation.

Hooded rats with bilateral lesions of the anterior part of the hippocampal formation (HIP), anterior region of the posterior parietal cortex (APC), or posterior region of the posterior parietal cortex (PPC) were compared with controls for their exploration of 5 objects in an open field, habituation of locomotion and object investigation, and response to spatial and nonspatial change. First, all groups displayed habituation of both locomotor and exploratory activity. Second, controls selectively reexplored displaced objects, and APC-lesioned rats reexplored all objects, whereas PPC- and HIP-lesioned rats failed to react to the spatial change. Third, a novel object induced reexploration in all groups. Results are consistent with the roles of the HIP and PPC in spatial information processing. Moreover, the APC and PPC are involved in attentional effortful processing and visuospatial information processing necessary for spatial representation, respectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Substitutional Atom Influence on the Electronic and Transport Properties of Mn4Si7

Mn₄Si₇ has been substituted with the following elements: Cu, Fe, Re and Cr on the Mn site, and Al, B, Ge, Sn, Ga, In, Na and Tl on the Si site. The Seebeck coefficient, electrical conductivity and power factor of the substitutional alloys have been evaluated by using density functional theory calculations, and the temperature dependence of the electronic transport properties has been investigated at different charge carrier concentrations by solving the semi-classical Boltzmann transport equation. We show that the substitution of Cu for Mn worsens the thermoelectric properties, while that with Fe appears the?most efficient for increasing the power factor. For In and Tl substitutions, the Seebeck coefficient is increased due to the high d-states contribution in the density of states at the Fermi level. Although the power factor is limited by a poor electrical conductivity, Mn₃₂Si₅₅Tl could exhibit a good figure of merit provided that the amount of Tl atoms is low (at most 1 at.%) and the charge carrier concentration is not too high (around 10²⁰ cm^?3).     

Simplification of a complex microbial antilisterial consortium to evaluate the contribution of its flora in uncooked pressed cheese

A complex microbial consortium derived from raw milk and composed of populations classified in 4 groups (lactic acid bacteria (A), Gram positive catalase positive bacteria (B), Gram negative bacteria (C) and yeasts (D)) can contribute to the inhibition of Listeria monocytogenes in the core of an uncooked pressed cheese. To identify what groups may be involved in the inhibition, the consortium was simplified by successively omitting one group at a time. Pasteurized milk was inoculated with these more or less complex consortia and their effects on L. monocytogenes count, pH, acids and volatile compounds in the core of uncooked pressed cheese were evaluated. The growth of L. monocytogenes was the highest in cheeses prepared with pasteurized milk and only St. thermophilus. Inhibition in other cheeses was expressed by comparison with growth in these ones. All the consortia containing both lactic acid bacteria (group A) and Gram positive catalase positive bacteria (group B)--ABCD, ABD, ABC, AB--were more inhibitory than those containing lactic acid bacteria on its own (A) or associated only with yeasts (AD) or/and Gram negative (ADC). Consortia without lactic acid bacteria were weakly inhibitory or had no effect. Gram positive catalase positive bacteria alone were not inhibitory although most of the species became established in the cheeses. The Lactobacillus population (Lb. casei, Lb. plantarum, Lb. curvatus and Lb. farciminis) was predominant in cheeses (9 log CFU/g) with a higher count than Leuconostoc (7 log CFU/g) and Enterococcus (7 log CFU/g). Lactobacillus counts were negatively correlated with those of L. monocytogenes (r=-0.84 at 18 days) and with the level of D-lactic acid. There was no correlation between L. monocytogenes and Leuconostoc or Enterococcus counts. Complex consortium ABCD and AB not only had a stronger inhibitory power in cheeses than consortium AD, they were also associated with the highest levels of L-lactic and acetic acids. All cheeses inoculated with lactic acid bacteria differed from those without by higher levels of ethyl formiate, pentane and alcohols (2-butanol, 2-pentanol), and lower levels of ketones (2-hexanone, 2,3-butanedione) and aldehydes (2-methyl-butanal). Levels of 2-methyl-butanal, 2-butanol and 2-pentanol were higher in ABCD and AB cheeses than in AD cheeses. Beside their contribution to the inhibition, their effect on cheese flavour must be evaluated.     

Optimization of laser cladding process using taguchi and EM methods for MMC coating production

This study investigates the influence of laser cladding parameters on the geometry and composition of metalmatrix composite (MMC) coatings. Composite coatings are made of a Ni-Cr-B-Si metallic matrix and of WC reinforcement with a volume fraction of 50%. Optical microscopy is used to characterize the coating geometry (height, width, and penetration depth) and to determine the real volumetric content of WC. Laser cladding on low-carbon steel substrate is carried out using a cw neodymium:yttrium-aluminum-garnet (Nd:YAG) laser, a coaxial powder injection system, and a combination of Taguchi and EM methods to design the experiments. This combination explores efficiently the multidimensional volume of laser cladding parameters. The results, which express the interrelationship between laser cladding parameters and the characteristics of the clad produced, can be used to find optimum laser parameters, to predict the responses, and to improve the understanding of laser cladding process. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

Left main coronary artery compression during primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is often associated with angina-like chest pain, the mechanism of which is controversial. A 37-year-old woman with severe PPH and angina had transient ischemic ECG changes and reversible anterior perfusion defect on 201thallium scintigraphy. Coronary angiography revealed severe stenosis of the left main coronary artery (LMCA) and otherwise normal vessels. After heart-lung transplantation, examination of the explanted heart showed normal coronary arteries. Compression of the LMCA by the dilated pulmonary artery trunk was responsible for myocardial ischemia. This mechanism should be considered in patients with PPH and angina and might contribute to the high sudden death rate.     

Clinical features and prognostic implications of familial hypertrophic cardiomyopathy related to the cardiac myosin-binding protein C gene

BACKGROUND: Little information is available on phenotype-genotype correlations in familial hypertrophic cardiomyopathy that are related to the cardiac myosin binding protein C (MYBPC3) gene. The aim of this study was to perform this type of analysis. METHODS AND RESULTS: We studied 76 genetically affected subjects from nine families with seven recently identified mutations (SASint20, SDSint7, SDSint23, branch point int23, Glu542Gln, a deletion in exon 25, and a duplication/deletion in exon 33) in the MYBPC3 gene. Detailed clinical, ECG, and echocardiographic parameters were analyzed. An intergene analysis was performed by comparing the MYBPC3 group to seven mutations in the beta-myosin heavy-chain gene (beta-MHC) group (n=52). There was no significant phenotypic difference among the different mutations in the MYBPC3 gene. However, in the MYBPC3 group compared with the beta-MHC group, (1) prognosis was significantly better (P<0.0001), and no deaths occurred before the age of 40 years; (2) the age at onset of symptoms was delayed (41+/-19 versus 35+/-17 years, P<0.002); and (3) before 30 years of age, the phenotype was particularly mild because penetrance was low (41% versus 62%), maximal wall thicknesses lower (12+/-4 versus 16+/-7 mm, P<0.03), and abnormal T waves less frequent (9% versus 45%, P<0.02). CONCLUSIONS: These results are consistent with specific clinical features related to the MYBPC3 gene: onset of the disease appears delayed and the prognosis is better than that associated with the beta-MHC gene. These findings could be particularly important for the purpose of clinical management and genetic counseling in familial hypertrophic cardiomyopathy.     

On the consistency of knowledge bases: the COVADIS system

It is currently thought in the knowledge-based systems (KBS) domain that sophisticated tools are necessary for helping an expert with the difficult task of knowledge acquisition. The problem of detecting inconsistencies is especially crucial. The risk of inconsistencies increases with the size of the knowledge base; for large knowledge bases, detecting inconsistencies "by hand" or even by a superficial survey of the knowledge base is impossible. Indeed, most inconsistencies are due to the interaction between several rules via often deep deductions. In this paper, we first state the problem and define our approach in the framework of classical logic. We then describe a complete method to prove the consistency (or the inconsistency) of knowledge bases that we have implemented in the COVADIS system.