Apport des techniques de prototypage rapide pour la validation fonctionnelle des assemblages de précision

Les techniques de prototypage rapide (PR) représentent une classe de processus de fabrication qui permet, automatiquement, l'obtention des pièces par dépôt d'un substrat par couches successives. La génération des couches se fait directement à partir des modèles virtuels issus des systèmes de Conception Assistée par Ordinateur (CAO). Actuellement, les pièces obtenues des machines de PR sont, généralement, employées pour l'inspection visuelle rapide, l'analyse de la forme et l'évaluation ergonomique au cours des diverses étapes du développement du produit. Cependant, la validation visuelle du modèle ne constitue pas le seul besoin en ingénierie car pour réaliser un assemblage fonctionnel, on doit aussi tenir compte de la précision dimensionnelle des pièces constituant cet assemblage. Or, les pièces issues des machines de PR ne permettent généralement pas un assemblage de précision fonctionnel. En effet, la précision des pièces produites par le PR est fortement liée au plan programmé de fabrication et à la précision du procédé lui-même. Malheureusement, ceux-ci sont rarement compatibles avec les exigences du modèle CAO en termes de dimension et de tolérance. Le sujet de ce mémoire porte sur l'apport des techniques de prototypage rapide pour la validation fonctionnelle des assemblages de précision. À cet effet, deux étapes ont été préconisées."--Résumé abrégé par UMI

Etiology of autistic features: the persisting neurotoxic effects of propionic acid

BACKGROUND: Recent clinical observations suggest that certain gut and dietary factors may transiently worsen symptoms in autism. Propionic acid (PA) is a short chain fatty acid and an important intermediate of cellular metabolism. Although PA has several beneficial biological effects, its accumulation is neurotoxic. METHODS: Two groups of young Western albino male rats weighing about 45 to 60 grams (approximately 21 days old) were used in the present study. The first group consisted of oral buffered PA-treated rats that were given a neurotoxic dose of 250 mg/kg body weight/day for three days, n = eight; the second group of rats were given only phosphate buffered saline and used as a control. Biochemical parameters representing oxidative stress, energy metabolism, neuroinflammation, neurotransmission, and apoptosis were investigated in brain homogenates of both groups. RESULTS: Biochemical analyses of brain homogenates from PA-treated rats showed an increase in oxidative stress markers (for example, lipid peroxidation), coupled with a decrease in glutathione (GSH) and glutathione peroxidase (GPX) and catalase activities. Impaired energy metabolism was ascertained through the decrease of lactate dehydrogenase and activation of creatine kinase (CK). Elevated IL-6, TNFα, IFNγ and heat shock protein 70 (HSP70) confirmed the neuroinflammatory effect of PA. Moreover, elevation of caspase3 and DNA fragmentation proved the pro-apoptotic and neurotoxic effect of PA to rat pups CONCLUSION: By comparing the results obtained with those from animal models of autism or with clinical data on the biochemical profile of autistic patients, this study showed that the neurotoxicity of PA as an environmental factor could play a central role in the etiology of autistic biochemical features

El papel de los medios de comunicación en la guerra civil siria

This study will show the mediatic change suffered by the Syrian civil war over these six years of conflict, reflected in the world¿s most influential media, from the western to the eastern, inlcuding social media and independent productions. Syria has been talked about these passed years by the local, national and international media, although it is visible that a total misinformation about the conflict is being broadcasted from the western media in comparison with the eastern media. This is something that this study will elaborate on, answering questions of why this is happening and what is their purpose.Este estudio mostrará el cambio mediático que ha sufrido la guerra civil siria a lo largo de estos 6 años de conflicto reflejado en los medios de comunicación internacionales más influyentes del planeta por una parte del bloque occidental y por otra el oriental, incidiendo también en la importancia de las redes sociales y los medios de comunicación independientes. Siria lleva más de seis años en boca de todo los medios, locales, nacionales e internacionales pero a pesar de todo esto existe una total desinformación del conflicto por parte del bloque mediático occidental comparado con el bloque mediático oriental algo que se tratará en este estudio y se verá la finalidad que tiene y el por qué.Al Bacha El Farra, L. (2017). El papel de los medios de comunicación en la guerra civil siria. Universitat Politècnica de València. http://hdl.handle.net/10251/89854TFG

Proinflammatory and proapoptotic markers in relation to mono and di-cations in plasma of autistic patients from Saudi Arabia

<p>Abstract</p> <p>Objectives</p> <p>Autism is a developmental disorder characterized by social and emotional deficits, language impairments and stereotyped behaviors that manifest in early postnatal life. This study aims to clarify the relationship amongst absolute and relative concentrations of K⁺, Na⁺, Ca²⁺, Mg²⁺and/or proinflammatory and proapoptotic biomarkers.</p> <p>Materials and methods</p> <p>Na⁺, K⁺, Ca²⁺, Mg²⁺, Na⁺/K⁺, Ca²⁺/Mg²⁺together with IL6, TNFα as proinflammatory cytokines and caspase3 as proapoptotic biomarker were determined in plasma of 25 Saudi autistic male patients and compared to 16 age and gender matching control samples.</p> <p>Results</p> <p>The obtained data recorded that Saudi autistic patients have a remarkable lower plasma caspase3, IL6, TNFα, Ca²⁺and a significantly higher K⁺compared to age and gender matching controls. On the other hand both Mg²⁺and Na⁺were non-significantly altered in autistic patients. Pearson correlations revealed that plasma concentrations of the measured cytokines and caspase-3 were positively correlated with Ca²⁺and Ca²⁺/K⁺ratio. Reciever Operating Characteristics (ROC) analysis proved that the measured parameters recorded satisfactory levels of specificity and sensitivity.</p> <p>Conclusion</p> <p>Alteration of the selected measured ions confirms that oxidative stress and defective mitochondrial energy production could be contributed in the pathogenesis of autism. Moreover, it highlights the relationship between the measured ions, IL6, TNFα and caspase3 as a set of signalling pathways that might have a role in generating this increasingly prevalent disorder. The role of ions in the possible proinflammation and proapoptic mechanisms of autistics' brains were hypothesized and explained.</p

Plasma fatty acids as diagnostic markers in autistic patients from Saudi Arabia

<p>Abstract</p> <p>Backgrounds</p> <p>Autism is a family of developmental disorders of unknown origin. The disorder is characterized by behavioral, developmental, neuropathological and sensory abnormalities, and is usually diagnosed between the ages of 2 and 10 with peak prevalence rates observed in children aged 5-8 years. Recently, there has been heightened interest in the role of plasma free fatty acids (FA) in the pathology of neurological disorders. The aim of this study is to compare plasma fatty acid profiles of Saudi autistic patients with those of age-matching control subjects in an attempt to clarify the role of FA in the etiology of autism.</p> <p>Methods</p> <p>26 autistic patients together with 26-age-matching controls were enrolled in the present study. Methyl esters of FA were extracted with hexane, and the fatty acid composition of the extract was analyzed on a gas chromatography.</p> <p>Results</p> <p>The obtained data proved that fatty acids are altered in the plasma of autistic patients, specifically showing an increase in most of the saturated fatty acids except for propionic acid, and a decrease in most of polyunsaturated fatty acids. The altered fatty acid profile was discussed in relation to oxidative stress, mitochondrial dysfunction and the high lead (Pb) concentration previously reported in Saudi autistic patients. Statistical analysis of the obtained data shows that most of the measured fatty acids were significantly different in autistic patients compared to age -matching controls.</p> <p>Conclusions</p> <p>Receiver Operating Characteristic (ROC) curve analysis shows satisfactory values of area under the curve (AUC) which could reflect the high degree of specificity and sensitivity of the altered fatty acids as biomarkers in autistic patients from Saudi Arabia.</p

Écophysiologie de l'agarophyte Gracilaria multipartita (Clémente) Harvey (Rhodophyceae, Gracilariales)

L’influence des principaux paramètres physico-chimiques (température, densité algale, lumière, salinité, sels nutritifs) sur la croissance de Gracilaria multipartita a été étudiée au laboratoire en conditions contrôlées. Les conditions requises pour une croissance maximale sont une densité algale comprise entre 0,5 et 3 g. l-1, un éclairement sous lumière blanche d’une intensité comprise entre 100 et 300 ?mol m-2s-1, le nitrate d’ammonium comme source préférentielle d’azote avec une concentration comprise entre 0,5 et 4 mM, une concentration en phosphates inférieure à 0,2 mM, une concentration en carbonates inférieure à 5mM et une salinité comprise entre 24 et 4 6 PPT. En fonction de cette capacité d’adaptation de l’espèce à des conditions physico-chimiques variées et de sa vitesse de croissance qui peut atteindre 2,5%j-1, G. multipartita pourrait être utilisé en aquaculture

Cycle biologique de l'agarophyte Gracilaria multipartita (Clemente) Harvey (Rhodophyceae, Gracilariales) sur la côte atlantique marocaine

Le cycle de croissance de Gracilaria multipartita, espèce commune du littoral marocain a été suivi pendant 2 années. Les nouvelles frondes se développent à partir du mois de janvier sur le disque pérennant. La croissance est maximale entre mai et juin. Après un arrêt de croissance pendant l’été, une nouvelle phase de croissance plus ou moins marquée selon les années est observée en automne. Les frondes dégénèrent ensuite pour laisser place à de nouvelles pousses en janvier. Les analyses statistiques ont confirmé ce cycle et désignent la température comme le facteur déterminant dans son déroulement. L’étude indique qu’il serait possible d’exploiter l’espèce à partir de juin, avant que les frondes ne commencent à dégénérer

Leverage versus volatility: Evidence from the Capital Structure of European Firms

The capital structure theory advocates a mix between debt and equity to optimize a firm‘s value (Modigliani & Miller, 1958). However, Islamic finance recognizes more conservative levels of debt for firms, based not on capital structure, but on debt to total assets or debt to market capitalization. This study is the first attempt to investigate the role of leverage in affecting the returns and the firm‘s share price volatility in relation to an Islamic finance perspective (IFP). The paper is based on a sample of 320 European companies distributed into different portfolios with high and low debt, high and low assets and focused on ten different countries. Comparative portfolio analysis was used to obtain a number of testable hypotheses, which specify the factors at the level of the firm and at the level of the market, in order to determine optimal financial risk. Specifically, we use the mean variance efficient frontier (MVEF) to confirm, in accordance with the theory, that a portfolio with a higher capital structure has higher volatility and lower returns compared to a portfolio with a lower capital structure. Then, the Shari‘ah screening method of improving the firm‘s stability in the market has been analyzed based on econometric analysis. Dynamic GMM is used in order to correlate the firm‘s leverage to total assets with its return and volatility in portfolios with high and low capital structure. To ensure the robustness of results, the business cycle effects have been considered after adding the firm and the country characteristics with a view to taking into account the heterogeneity across different firms and different markets. The preliminary results tend to indicate that there are significant correlations between capital structure and both returns and volatility, but not necessarily with high debt to assets given different sizes and growth of firms. The paper suggests that are three main factors which need to be considered by the firms in order to improve their stability in the market: firstly, the level of capital structure but not the debt to total assets as suggested by some scholars using the IFP; secondly, the capitalization or the firm size and finally, the level of the sovereign debt and country dynamics. Although the latter may be beyond the firm‘s control, it is up to the firm to consider its own market with implications on its leverage policy in relation to the frequency-dependent strategy