Science & Mathematics

Deux espèces de Campylobacter sont fréquemment à l’origine de gastro‐entérites chez l’homme, Campylobacter jejuni et Campylobacter coli. Les conséquences peuvent être graves chez les jeunes enfants, les personnes âgées ou encore les personnes immunodéprimées et nécessitent alors le recours aux antibiotiques (fluoroquinolones ou macrolides). Malheureusement, des souches de Campylobacter résistantes aux fluoroquinolones ou aux macrolides sont présentes dans les élevages et dans les produits de consommation. Ces souches résistantes ont été sélectionnées en élevage du fait de l’utilisation de ces antibiotiques, et des modifications du patrimoine génétique permettent à Campylobacter de résister, de survivre, voire de se multiplier en la présence de l’antibiotique. Que se passe-t-il ensuite ?

Rapid urbanization in China has triggered the mass migration of rural populations to cities. These policies have resulted in a shortage of construction land for the urban population and in an inefficient use of rural homestead, causing a tremendous waste of rural land resources. Rural homestead transfer has been identified as a tool to solve this problem: the saved construction land can be reclaimed to cultivated land, and the construction rights are transferred to urban areas, where they can be used to build new households for the demanding population. We consider that transaction costs analysis can help understand the governance structures of the homestead processes, and provide avenues for further research and policy recommendations. Our article draws on the practices and experiences gained in three areas in rural China (Jinzhai, Yiwu, and Jiangning in the Anhui, Zhejiang, and Jiangsu Provinces, China). Based on the empirical cases and information produced from the villages and households survey, we developed an analytical framework of transaction cost. Results suggest that Yiwu has lower assets specificity, lower uncertainty, and transaction frequency, hence the market driven model played a major role. In Jinzhai, which presents higher assets specificity, higher uncertainty, and transaction frequency, the government-oriented model also played a major role. In Jiangning, where most transaction attributes are situated in the middle, the mixed-oriented model acted as a main role in the local area. Our conclusion shows that various governance structures are appropriate for different areas of rural China, which is significantly related to the local transaction attributes. We suggest promoting the governance structure which corresponds to the local resource endowment, human and residential condition, the cultural atmosphere, and also the institutional (official) atmosphere. Matched with the government or/and market governance structure, it may develop the resource allocation efficiency and improve economic performance.

It is increasingly acknowledged that a sex and gender specificity affects the occurrence, development, and consequence of a plethora of pathologies. Mitochondria are considered as the powerhouse of the cell because they produce the majority of energy-rich phosphate bonds in the form of adenosine tri-phosphate (ATP) but they also participate in many other functions like steroid hormone synthesis, reactive oxygen species (ROS) production, ionic regulation, and cell death. Adequate cellular energy supply and survival depend on mitochondrial life cycle, a process involving mitochondrial biogenesis, dynamics, and quality control via mitophagy. It appears that mitochondria are the place of marked sexual dimorphism involving mainly oxidative capacities, calcium handling, and resistance to oxidative stress. In turn, sex hormones regulate mitochondrial function and biogenesis. Mutations in genes encoding mitochondrial proteins are the origin of serious mitochondrial genetic diseases. Mitochondrial dysfunction is also an important parameter for a large panel of pathologies including neuromuscular disorders, encephalopathies, cardiovascular diseases (CVDs), metabolic disorders, neuropathies, renal dysfunction etc. Many of these pathologies present sex/gender specificity. Here we review the sexual dimorphism of mitochondria from different tissues and how this dimorphism takes part in the sex specificity of important pathologies mainly CVDs and neurological disorders.

Introduction: Prediction of performance and well-being are two essential keys in sports performance. Objective: The study aimed to map different positions regarding the way in which individuals integrated mentally five elements of eudaimonic well-being (relatedness, autonomy, competence, mental vitality and physical vitality) for predicting the degree of performance at the beginning of a match. Method: Twenty-four non-athletes, 44 amateur athletes and 26 professional athletes indicated their prediction of performance in 32 scenarios constructed from the combination of these elements of well-being. Cluster analysis, ANOVAs, and chi-square test have been done. Results: Two positions on prediction of performance were found. The first cluster was called "Sometimes Performance Prediction" and the second cluster was named "Seldom Performance Prediction". The five elements had a positive effect on the prediction of performance. The composition of both clusters was linked to the level of involvement in sport. Conclusion: Offering athletes a "well-being environment" may lead to predict the sports performance.

AbstractParatuberculosis is a worldwide disease causing production losses in dairy cattle herds. Variability of cattle response to exposure to Mycobacterium avium subsp. paratuberculosis (Map) has been highlighted. Such individual variability could influence Map spread at larger scale. Cattle resistance to paratuberculosis has been shown to be heritable, suggesting genetic selection could enhance disease control. Our objective was to identify which phenotypic traits characterising the individual course of infection influence Map spread in a dairy cattle herd. We used a stochastic mechanistic model. Resistance consisted in the ability to prevent infection and the ability to cope with infection. We assessed the effect of varying (alone and combined) fourteen phenotypic traits characterising the infection course. We calculated four model outputs 25 years after Map introduction in a naïve herd: cumulative incidence, infection persistence, and prevalence of infected and affected animals. A cluster analysis identified influential phenotypes of cattle resistance. An ANOVA quantified the contribution of traits to model output variance. Four phenotypic traits strongly influenced Map spread: the decay in susceptibility with age (the most effective), the quantity of Map shed in faeces by high shedders, the incubation period duration, and the required infectious dose. Interactions contributed up to 12% of output variance, highlighting the expected added-value of improving several traits simultaneously. Combinations of the four most influential traits decreased incidence to less than one newly infected animal per year in most scenarios. Future genetic selection should aim at improving simultaneously the most influential traits to reduce Map spread in cattle populations.

Since 2014, the ECB has applied a negative interest rate on the excess reserves (and deposit facilities) of commercial banks. This policy is complementary to Quantitative Easing (QE), a program whereby the ECB purchases securities on financial markets. Indeed, the QE provides liquidity to the banks and negative interest rates encourage them to reallocate this liquidity. The negative reserve rate amplifies the fall in short-term and long-term market rates and reinforces the incentive for commercial banks to operate reallocation on their portfolios towards riskier assets. The total amount of liquidity subject to a negative interest rate is 1047 billion euros. Negative interest rates should reduce interest rate margins but the impact on profitability is mitigated by the capital gains banks realise when selling securities to the ECB under QE, by the possibility banks have to finance themselves at negative rates, by a decrease in the risk of default and by the possibility to raise non-interest income.

Plastics have now invaded our daily lives. They are the symbol of the consumer society, because they are considered a non-noble material: consumers equate it with a disposable product after use. Since plastics are not degradable, they represent a real danger to the environment, fauna and flora.The objective of this thesis work was to develop in collaboration with the Institute of Analytical Sciences and Physico-Chemistry for Environment and Materials (Pau University) new formulations with natural additives to produce resistant and recyclable plastics. Two types of resins were used: isotactic polypropylene (i-PP) and low density polyethylene (LDPE). Natural antioxidants such as ascorbic acid, alpha-tocopherol and flaxseed oil were tested and encapsulated to improve their resistance to degradation. Thermal and rheological characterizations of resins have shown superior qualities to current commercial resins. We were able to demonstrate that the plastics obtained could be recycled 9 times without losing their characteristics. Tests with trays made with the developed products are underway to validate the developed models.

This study presents a streamlined and gentle approach to the preparation of wine samples for lead determination, eliminating the need for concentrated acid digestion. The method relies on a pass-through solid-phase extraction (SPE) cleanup employing a polymeric styrene-divinylbenzene solid sorbent to selectively purify the wine matrix. Lead was quantified using either graphite furnace atomic absorption spectroscopy (AAS) or a portable electrochemical sensor (MetalSens, OliSens, France). Ultraperformance liquid chromatography (UPLC) analysis of phenolic acids and flavonoids confirmed that the purification step effectively removes most organic interferences without compromising lead detection, with recovery rates ranging from 94 to 101 %. This proposed matrix cleanup minimizes fouling of the pyrolytic AAS platform, enables reliable reuse of SPE cartridges for up to five cycles, and facilitates rapid and accurate electrochemical lead determination in wine, with deviations within 15 % of reference AAS measurements.

Cet article traite du TRAITEMENT COMPTABLE DES ELEMENTS INCORPORELS en EUROPE

The chemotaxis response of E. coli to metal cations is less understood than their response to organic molecules. Using dark-field videomicroscopy, E. coli behavior was analyzed in a 17 mm-long microfluidic channel exposed to a Zn(NO 3 ) 2 chemorepellent gradient, generated by a 250 mM solution placed in a well at the channel extremity, with or without prior Zn 2+ pre-exposure of the cultures (10 µM). The bacteria exhibited an escape wave away from the zinc source. Compared to unexposed cultures, zinc preexposure resulted in a constant and shorter passage time at a given position of the wave peak, despite unchanged growth and swimming speed. The time lag decreased with growth duration. Given the onedimensional gradient setup, this decrease is associated to a reduced diffusion duration from the Zn 2 ⁺ source. The content of Zn 2 ⁺ in the extracellular medium at the peak of the wave is therefore lower, but allows bacteria to escape more rapidly. These findings suggested an increase in bacterial Zn 2 ⁺ sensitivity. By analogy to Ni 2 ⁺ binding to the cytoplasmic HAMP domain of the Tar receptor, Zn 2 ⁺ likely triggers a chemorepellent response through a cytoplasmic receptor. The activation of this receptor relies on the available zinc pool, which is specifically buffered by substantial other intracellular zinc reservoirs. In this model, saturating the reservoirs in pre-exposed cultures would enable the fastest response time, and a gradual filling of the reservoirs in unexposed cells would reduce a delay in chemotactic escape.

Evaluations de l'évolution des conduites liées à l'exercice des nouvelles technologies en contexte scolaire et périscolaire depuis 1989 : influence de la pédagogie assistée par ordinateur, des logiciels créés pour le grand public, de l'apparition des réseaux de communication tels internet. Les comportements actuels introduisent une relation nouvelle entre l'espace familial et l'espace scolaire, entre l'oral et l'écrit, entre les dimensions monologiques et dialogiques. La mondialisation des phénomènes crée à tous les niveaux d'exercice des faits de fractures numérique à prendre en compte.