136 research outputs found
New insulation fiberboards from sunflower cake with improved thermal and mechanical properties
New insulation fiberboards from sunflower cake with improved thermal and mechanical properties were produced by pressing at ambient temperature. Best compromise between mechanical and heat insulation properties (λ = 77.6 mW/m K at 25°C) was a starch-based board with 20% binder content. Because of its promising heat insulation properties, this new fiberboard could be positioned on walls and ceilings for thermal insulation of buildings. The bulk cake was an even better insulation material (only 62.0 mW/m K for thermal conductivity at 25°C): usable as loose fill in the attics of houses
An autonomous method of optimization targeting for an object detection system based on responsability analysis
Object extraction systems performances are not homogeneous over different corpora because objects can take many
different aspects within such sets. An adaptation of these systems is thus required in order to maintain equal performances
over every kind of object the system may be applied on. Focusing on the issue of parameters optimization, a
method has been developed to restrict optimization to parameters of operators which compose the system, responsible
for the different categories of errors produced by the system. Two stages are involved in our method. The first one is
dedicated to the analysis of the system performances and leads to the extraction of the different error categories already
mentionned. The second one relates to the analysis of the behavior of the different operators, leading to extract a single
operator responsible for each error category. Experiments have been carried out over a video text detection system.Les systÚmes d'extraction d'objets sont mis à mal par la diversité de ces derniers. Leur adaptation est donc
nécessaire pour maintenir des performances équivalentes quelle que soit la nature des objets sur lesquels
ceux-ci sont appliqués. S'attachant plus particuliÚrement, dans l'optique de cette adaptation, à la tùche
d'optimisation du paramétrage de ces systÚmes, nous proposons dans cet article une méthode originale de
ciblage de l'optimisation aux seuls paramÚtres des opérateurs du systÚme estimés responsables des
différentes catégories d'erreurs produites par le systÚme. Cette méthode s'appuie alors sur deux analyses
distinctes. La premiÚre porte sur les performances du systÚme considéré et permet d'extraire les différentes
catégories d'erreur déjà mentionnées. La seconde concerne le fonctionnement des différents opérateurs
composant le systÚme et donne lieu à la détermination d'un opérateur responsable pour chaque catégorie
d'erreur. Une application de cette méthodologie à un systÚme de détection de texte est par ailleurs détaillée
Le processus de production du risque « submersion marine » en zone littorale : lâexemple des territoires « Xynthia »
Les lourdes consĂ©quences des catastrophes naturelles restent (trop) souvent expliquĂ©es, Ă travers les mĂ©dias notamment, par les phĂ©nomĂšnes de changements climatiques, par la dĂ©faillance des systĂšmes de dĂ©fense ou par le caractĂšre exceptionnel des conditions naturelles comme ce fut le cas lors des Ă©vĂ©nements de fĂ©vrier 2010 « Xynthia ». Or de tels phĂ©nomĂšnes de submersion marine ont dĂ©jĂ atteint le littoral atlantique par le passĂ©. Certes les dommages matĂ©riels et humains Ă©taient moindres mais les conditions naturelles similaires. La diffĂ©rence se trouve dans lâoccupation des sols bien plus tournĂ©e vers lâurbanisation ces 50 derniĂšres annĂ©es. Notre objectif est de montrer que loin dâĂȘtre le fruit dâun phĂ©nomĂšne exceptionnel, la submersion marine issue de la tempĂȘte Xynthia est lâaboutissement dâun processus de production du risque massif et rĂ©cent. LâĂ©tude a concernĂ© les communes de Charente-Maritime et VendĂ©e qui ont subi des pertes humaines. La densification de lâurbanisation et plus gĂ©nĂ©ralement lâamĂ©nagement du territoire, mĂȘme sâils ne sont pas Ă lâorigine du phĂ©nomĂšne, ont accru les enjeux toujours plus vulnĂ©rables dans les zones Ă risques, accentuant ainsi les consĂ©quences matĂ©rielles et humaines des phĂ©nomĂšnes naturels. La tempĂȘte Xynthia a gĂ©nĂ©rĂ© une submersion marine dâoccurrence sans doute rare mais qui rencontre des dynamiques territoriales trĂšs rapides. Un espace quasi dĂ©sert peut se retrouver en trente ans fortement urbanisĂ©. Cet exemple rappelle que les mesures de prĂ©vention du risque en particulier les mesures de rĂ©glementation de lâoccupation des sols doivent sâapprĂ©cier sur la longue durĂ©e car leur transgression est quasiment irrĂ©versible.The huge aftermaths of disasters remain (too) often explained, through the media, by the climate change or by the failure of flood defenses, as was the storm Xynthia that hit the western part of France in February 2010. However such phenomena of marine flooding linked to windstorm have already struck the Atlantic coast in the past. Material and human damage were lower although natural conditions were quite similar. The difference lies in the urbanization that has widely grown for fifty years. Our goal is to show that the toll of the Xynthia storm is not essentially due to an exceptional marine flooding phenomenon. On the contrary, it is due to the accumulation of vulnerable assets in flood prone zone. The study mainly relies on the seven communes of Charente-Maritime and VendĂ©e which suffered human losses. The densification of urbanization and more generally the lack of land use control led to an anarchic development of assets at risk especially touristic plants and secondary homes. The marine flooding generated by Xynthia Storm has probably a low return period but the low frequency phenomenon has met very rapid territorial dynamics. Thus the process of âproduction of riskâ had been very fast. A quite uninhabited space can be turned into an highly urbanized territory within thirty years. This example reminds that the measures of prevention of risk, especially land use planning must be taken and assessed on the long term because their transgression is irreversible
Granzyme B enters the mitochondria in a Sam50-, Tim22- and mtHsp70-dependent manner to induce apoptosis
We have found that granzyme B (GB)-induced apoptosis also requires reactive oxygen species resulting from the alteration of mitochondrial complex I. How GB, which does not possess a mitochondrial targeting sequence, enter this organelle is unknown. We show that GB enters the mitochondria independently of the translocase of the outer mitochondrial membrane complex, but requires instead Sam50, the central subunit of the sorting and assembly machinery that integrates outer membrane ÎČ- barrel proteins. Moreover, GB breaches the inner membrane through Tim22, the metabolite carrier translocase pore, in a mitochondrial heat-shock protein 70 (mtHsp70)-dependent manner. Granzyme A (GA) and caspase-3 use a similar route to the mitochondria. Finally, preventing GB from entering the mitochondria either by mutating lysine 243 and arginine 244 or depleting Sam50 renders cells more resistant to GB-mediated reactive oxygen species and cell death. Similarly, Sam50 depletion protects cells from GA-, GM- and caspase-3-mediated cell death. Therefore, cytotoxic molecules enter the mitochondria to induce efficiently cell death through a noncanonical Sam50-, Tim22- and mtHsp70-dependent import pathway
The thermo-mechano-chemical twin-screw reactor, a new perspective for the biorefinery of sunflower whole plant: aqueous extraction of oil and other biopolymers, and production of biodegradable fiberboards from cake
Biorefinery of sunflower whole plant was performed successfully using a thermo-mechano-chemical twin-screw reactor. This led to the aqueous extraction of oil and other biopolymers like proteins, pectins and non pectic sugars. It resulted in the overall fractionation of biomass, thus allowing a complete valorization of the input. This biorefinery process was not only efficient but it was also environment-friendly. In addition, it contributed to the production of different end products for various industrial applications. Firstly, the hydrophilic phase will be recycled to the process. Secondly, the densest oil-in-water emulsion is a promising candidate for the formulation of cosmetic creams. Thirdly, the upper hydrophobic phase will be usable for the waterproofing treatment of the surface of agromaterials by coating. Its demixing will also lead to the production of proteins with tensioactive properties. These will serve for the food industry. Lastly, the cake was a mixture of plasticized proteins and lignocellulosic fibers. It was thus considered as a natural composite. Its molding into cohesive fiberboards was conducted successfully using both thermopressing and compression molding processes. The self-bonded boards with high density will be suitable for use as load bearing boards in dry conditions (floor underlayers, interior partitions, furniture, etc.). Positioned in walls and ceilings, boards with medium and low density will contribute to the heat insulation of buildings. In addition, the bulk cake will be also usable as a loose fill insulation material. As proposed, this flow chart thus allows a valorization for all fractions originating from the twin-screw reactor
Bat responses to changes in forest composition and prey abundance depend on landscape matrix and stand structure
Despite the key importance of the landscape matrix for bats, we still not fully understand how the effect of forest composition interacts at combined stand and landscape scales to shape bat communities. In addition, we lack detailed knowledge on the effects of local habitat structure on bat-prey relationships in forested landscapes. We tested the assumptions that (i) forest composition has interacting effects on bats between stand and landscape scales; and (ii) stand structure mediates prey abundance effects on bat activity. Our results indicated that in conifer-dominated landscapes (>â80% of coniferous forests) bat activity was higher in stands with a higher proportion of deciduous trees while bats were less active in stands with a higher proportion of deciduous trees in mixed forest landscapes (~â50% of deciduous forests). Moth abundance was selected in the best models for six among nine bat species. The positive effect of moth abundance on Barbastella barbastellus was mediated by vegetation clutter, with dense understory cover likely reducing prey accessibility. Altogether, our findings deepen our understanding of the ecological processes affecting bats in forest landscapes and strengthen the need to consider both landscape context and trophic linkage when assessing the effects of stand-scale compositional and structural attributes on bats
Mir-21 Suppression Promotes Mouse Hepatocarcinogenesis.
The microRNA 21 (miR-21) is upregulated in almost all known human cancers and is considered a highly potent oncogene and potential therapeutic target for cancer treatment. In the liver, miR-21 was reported to promote hepatic steatosis and inflammation, but whether miR-21 also drives hepatocarcinogenesis remains poorly investigated in vivo. Here we show using both carcinogen (Diethylnitrosamine, DEN) or genetically (PTEN deficiency)-induced mouse models of hepatocellular carcinoma (HCC), total or hepatocyte-specific genetic deletion of this microRNA fosters HCC development-contrasting the expected oncogenic role of miR-21. Gene and protein expression analyses of mouse liver tissues further indicate that total or hepatocyte-specific miR-21 deficiency is associated with an increased expression of oncogenes such as Cdc25a, subtle deregulations of the MAPK, HiPPO, and STAT3 signaling pathways, as well as alterations of the inflammatory/immune anti-tumoral responses in the liver. Together, our data show that miR-21 deficiency promotes a pro-tumoral microenvironment, which over time fosters HCC development via pleiotropic and complex mechanisms. These results question the current dogma of miR-21 being a potent oncomiR in the liver and call for cautiousness when considering miR-21 inhibition for therapeutic purposes in HCC
Pancreatic ÎČ-cell imaging in humans: Fiction or option?
Diabetes mellitus is a growing worldwide epidemic disease, currently affecting 1 in 12 adults. Treatment of disease complications typically consumes âŒ10% of healthcare budgets in developed societies. Whilst immuneâmediated destruction of insulinâsecreting pancreatic ÎČ cells is responsible for Type 1 diabetes, both the loss and dysfunction of these cells underly the more prevalent Type 2 diabetes. The establishment of robust drug development programmes aimed at ÎČâcell restoration is still hampered by the absence of means to measure ÎČâcell mass prospectively in vivo, an approach which would provide new opportunities for understanding disease mechanisms and ultimately assigning personalized treatments. In the present review, we describe the progress towards this goal achieved by the Innovative Medicines Initiative in Diabetes, a collaborative publicâprivate consortium supported by the European Commission and by dedicated resources of pharmaceutical companies. We compare several of the available imaging methods and molecular targets and provide suggestions as to the likeliest to lead to tractable approaches. Furthermore, we discuss the simultaneous development of animal models that can be used to measure subtle changes in ÎČâcell mass, a prerequisite for validating the clinical potential of the different imaging tracers
Spatiotemporally Controlled Cardiac Conduction Block Using High-Frequency Electrical Stimulation
Background:
Methods for the electrical inhibition of cardiac excitation have long been sought to control excitability and conduction, but to date remain largely impractical. High-amplitude alternating current (AC) stimulation has been known to extend cardiac action potentials (APs), and has been recently exploited to terminate reentrant arrhythmias by producing reversible conduction blocks. Yet, low-amplitude currents at similar frequencies have been shown to entrain cardiac tissues by generation of repetitive APs, leading in some cases to ventricular fibrillation and hemodynamic collapse in vivo. Therefore, an inhibition method that does not lead to entrainment â irrespective of the stimulation amplitude (bound to fluctuate in an in vivo setting) â is highly desirable.
Methodology/Principal Findings:
We investigated the effects of broader amplitude and frequency ranges on the inhibitory effects of extracellular AC stimulation on HL-1 cardiomyocytes cultured on microelectrode arrays, using both sinusoidal and square waveforms. Our results indicate that, at sufficiently high frequencies, cardiac tissue exhibits a binary response to stimulus amplitude with either prolonged APs or no effect, thereby effectively avoiding the risks of entrainment by repetitive firing observed at lower frequencies. We further demonstrate the ability to precisely define reversible local conduction blocks in beating cultures without influencing the propagation activity in non-blocked areas. The conduction blocks were spatiotemporally controlled by electrode geometry and stimuli duration, respectively, and sustainable for long durations (300 s).
Conclusion/Significance:
Inhibition of cardiac excitation induced by high-frequency AC stimulation exhibits a binary response to amplitude above a threshold frequency, enabling the generation of reversible conduction blocks without the risks of entrainment. This inhibition method could yield novel approaches for arrhythmia modeling in vitro, as well as safer and more efficacious tools for in vivo cardiac mapping and radio-frequency ablation guidance applications
Low loss coatings for the VIRGO large mirrors
présentée par L. PinardThe goal of the VIRGO program is to build a giant Michelson type interferometer (3 kilometer long arms) to detect gravitational waves. Large optical components (350 mm in diameter), having extremely low loss at 1064 nm, are needed. Today, the Ion beam Sputtering is the only deposition technique able to produce optical components with such performances. Consequently, a large ion beam sputtering deposition system was built to coat large optics up to 700 mm in diameter. The performances of this coater are described in term of layer uniformity on large scale and optical losses (absorption and scattering characterization). The VIRGO interferometer needs six main mirrors. The first set was ready in June 2002 and its installation is in progress on the VIRGO site (Italy). The optical performances of this first set are discussed. The requirements at 1064 nm are all satisfied. Indeed, the absorption level is close to 1 ppm (part per million), the scattering is lower than 5 ppm and the R.M.S. wavefront of these optics is lower than 8 nm on 150 mm in diameter. Finally, some solutions are proposed to further improve these performances, especially the absorption level (lower than 0.1 ppm) and the mechanical quality factor Q of the mirrors (thermal noise reduction)
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