Occurrence of Yersinia enterocolitica in milk and dairy products in Morocco.

A total of 227 samples of milk and dairy products were examined for the presence of Yersinia enterocolitica. Yersinia spp. were recovered from 11 of 30 raw milks (36.6%), one of 20 pasteurized milks (5%), 15 of 63 traditional fermented milks (23.8%), seven of 94 cheeses and one of 20 cream samples (5%). The overall incidence of Y. enterocolitica in milk and dairy products was 6.6%. The other Yersinia species were Y. intermedia, Y. kristensenii, Y. frederiksenii and Y. pseudotuberculosis. Y. enterocolitica was detected only in raw milk (30% of the samples), in traditional fermented milks (6.3%) and in raw milk-made cheese (4%). The majority of the Y. enterocolitica isolates were of biotype 1 (environmental strains). The Celfulodin-Irgasan-Novobiocin (CIN) Agar was found to be more efficient than the Mac Conkey Agar in the isolation of Yersinia organisms.     

Structure of a hydroxymycolic acid potentially involved in the synthesis of oxygenated mycolic acids of the Mycobacterium tuberculosis complex

Mycolic acids are believed to play a crucial role in the architecture of the mycobacterial envelope. However, very few steps of their biosynthetic pathway have yet been elucidated. We previously isolated [Dubnau, E., Lanéelle, M. A., Soares, S., Bénichou, A., Vaz, T., Promé, D., Promé, J. C., Daffé, M. & Quémard, A. (1997) Mycobacterium bovis BCG genes involved in the biosynthesis of cyclopropyl keto- and hydroxy-mycolic acids, Mol. Microbiol. 23, 313-322] a gene cluster from Mycobacterium bovis BCG, cmaA-D, which confers upon M. smegmatis the ability to synthesize cyclopropanated ketomycolic acid, and a new type of mycolic acid which is hydroxylated. A meticulous analysis of all the mycolic-like fatty acids of M. bovis BCG and M. tuberculosis showed that these organisms produce small amounts of the hydroxymycolic acid. The structure of this molecule, determined by NMR spectroscopy, mass spectrometry and stereochemical studies, strongly suggests that there is a direct biosynthetic relationship between the keto- and the hydroxy-mycolic acids.     

Anti-platelet activity of the peptides composing the lebetin 1 family, a new class of inhibitors of platelet aggregation

We have purified from Vipera lebetina venom a family of inhibitors of platelet aggregation, named Lebetins. They are composed of two peptide groups of short (Lebetin 1: L1alpha: GDNKPPKKGPPNG; L1beta: DNKPPKKGPPNG) and long (Lebetin 2: L2alpha: GDNKPPKKGPPNGCFGHKIDRIGSHSGLGCNKVDDNKG; L2beta: DNKPPKKGPPNGCFGHKIDRIGSHSGLGCNKVDDNKG) size. The sequence presenting anti-platelet activity is mainly present within the Lebetin 1 sequence [Barbouche, R. Marrakchi, N., Mansuelle, P., Krifi, M., Fenouillet, E., Rochat, H. and El Ayeb, M. (1996) Novel anti-platelet aggregation polypeptides from Vipera lebetina venom: isolation and characterization. FEBS Lett. 392, 6-10]. Here, the peptides that compose the Lebetin 1 family were synthesized. Their respective activity was determined. Synthetic L1alpha and L1beta inhibited collagen-induced platelet aggregation in the nanomolar range. A peptide corresponding to L1beta deleted by D at its N terminus (L1gamma) also inhibited platelet aggregation potently; further truncation of L1gamma impaired its activity. Because L1 peptides efficiently inhibited fibrinogen-induced alpha-chymotrypsin treated-platelet aggregation, we tested whether they act mainly through the inhibition of platelet binding to fibrinogen and showed that they failed to inhibit platelet binding to fibrinogen-coated wells. The activity of L1 peptides was also tested in vivo: their intravenous administration strongly inhibited collagen-induced thrombocytopenia in rats.     

Cerastocytin, a new thrombin-like platelet activator from the venom of the Tunisian viper Cerastes cerastes

Cerastocytin, a thrombin-like enzyme from the venom of the desert viper, Cerastes cerastes, has been purified to homogeneity by fast performance liquid chromatography (FPLC) on Mono-Q and Mono-S columns. It is a basic protein (isoelectric point higher than 9) made of a single polypeptide chain of 38 kDa. Its N-terminal polypeptide sequence shows strong similarities with other thrombin-like enzymes from snake venoms. Nanomolar concentrations of cerastocytin induce aggregation of blood platelets. This activity is inhibited by chlorpromazine, theophylline and mepacrine, as in the case of platelet aggregation stimulated by low doses of thrombin. Cerastocytin also possesses an amidolytic activity measured with the thrombin chromogenic substrate S-2238. The platelet aggregating activity and the amidolytic activity of cerastocytin were inhibited by PMSF, TPCK, TLCK and soybean trypsin inhibitors, suggesting that cerastocytin is a serine proteinase. On the other hand, both amidolytic activity and platelet aggregating activity of cerastocytin were unaffected by hirudin or by antithrombin III in the presence of heparin. High concentrations of cerastocytin (1-10 microM) also cleaved prothrombin and Factor X.     

Improved preventive maintenance in the framework of forecasting problem under subcontractor constraint

The paper presents a new improved preventive maintenance strategy for a forecasting problem of production and maintenance optimisation under subcontractor constraint. In order to satisfy the customer, the manufacturing system consists of a principal machine M₁ and called upon subcontractor machine M_s. Knowing that both machines are subjected to random failures, failure rate of main machine increases with time and according to production rates. An improved preventive maintenance strategy is used for control of the machine M₁, whereas subcontractor machine M_s is uncontrollable from preventive maintenance point of view. An analytic formulation of problem has been proposed in order to determine the economical production plans for M₁ and M_s. An improved maintenance strategy (IMS) is developed in order to minimise the total production loss, when the subcontractor machine is unavailable. It consists of determining the best time to perform preventive maintenance actions taking into account production rates, history of M₁ and the state of subcontractor machine M_s. Numerical results and sensitivity analysis are presented to highlight the performance measure and the usefulness of the IMS.     

Emotional speaker recognition in real life conditions using multiple descriptors and i-vector speaker modeling technique

Multimedia Tools and Applications - Emotional speaker recognition under real life conditions becomes an urgent need for several applications. This paper proposes a novel approach using multiple...     

Speech enhancement based on perceptual filter bank improvement

In this paper, a new denoising approach is presented based on perceptual analysis. The noisy signal is split by a gammatone filterbank with nonlinear frequency distributions according to ERB scale. The frequency masking threshold is calculated in each sub-band according to the Johnston model in the output of the Wiener filter. This threshold is then used in the gain function given by the perceptual filter. The evaluation tests are performed by using objective criterion including perceptual evaluation of speech quality as well as subjective criterion including mean opinion score. Obtained results show that the proposed method achieves best results in terms of quality and intelligibility of enhanced signal.     

Graphical Programming and the Development of Construction Robots

Abstract: Complexity, multidisciplinarity, and algorithmic inherency are characteristics of construction robotic systems. Controlling the development process of such systems requires the adoption of a development model based on Systems Engineering principles. The software‐development process is an important aspect of the system, which requires a development environment that can cope with this complexity. Using traditional programming languages (textual) requires highly trained programmers for this purpose, which involves high cost and long development time. In the present work Graphical Programming (iconic) is used as the software development environment because it is highly modular and allows concurrent development, both of which save on time and cost. It also enables nonexpert programmers to produce software capable of coping with the system complexity. A detailed case study of the software development process for an existing tool manipulation robot known as Starlifter is presented. Use of the LabVIEW package is demonstrated for both onboard system control and off‐line project management.     

Biocomposites based on polycaprolactone reinforced with alfa fibre mats

To the best of our knowledge, this is the first report of combining alfa fibres with polycaprolactone (PCL) and using impregnation as a processing technique. Alfa fibres were used to prepare films that were impregnated with PCL solutions in order to produce composites in a continuous process. The resultant composites were studied by scanning electron microscopy, which showed that the PCL matrix formed continuous and homogeneous films. Dynamic mechanical analyses showed that the rubbery plateau of the virgin matrix was significantly prolonged. Differential scanning calorimetry showed that the crystallisation capacity of the PCL matrix increased with an increase in the reinforcing cellulose. Finally, the produced composites were assessed by performing contact angle measurements of a water droplet, and it was revealed that this parameter increased up to 130°, indicating that their wettability had decreased drastically.