Comparison of conventional and High Velocity Compaction of alumina powders

International audienceCeramic compacts can be usually prepared by uniaxial pressing in a die made of stainless steel, but the pressure applied is limited and density gradients occur in many cases. Recently a new forming method in powder metallurgy, the High Velocity Compaction (HVC) has been applied to ceramic powders. This method is similar to conventional pressing but consists in making an ram falling down at a very high speed to the upper punch. The kinetic energy is converted into a strike that produces a high pressure in a really short time. By controlling the kinetic energy, it is possible to apply a desired pressure that can be extremely high (up to 1 GPa) without any damage for the tool. The aim of the study is to compare the process conditions and the properties of green compacts elaborated by the two methods (conventional and HVC) for a similar forming pressure: forming pressure, green density (homogeneity), pore size distribution of the tablets, and then the sintering behavior, the shrinkage, the final density and microstructure of the ceramic material are studied

Forest management cessation and biodiversity: a synthesis of a nationwide French project

Extending the network of strict forest reserves is one of the conservation measures promoted by the French National Strategy for Biodiversity improvement. According to the scientific literature, strict forest reserves may help preserving a part of the biodiversity that is threatened by forestry. However, this strategy is based on poor knowledge in the temperate context and available studies may suffer from methodological shortcomings. The national-scale project named "Forest management, Naturalness and Biodiversity" aims at quantifying the effects on forest structure and biodiversity of management abandonment in strict reserves. Based on a meta-analysis of worldwide literature and original data from 213 study plots set up in 15 forest sites throughout France - around half of the plots in forests left unmanaged for from 8 to 148 years (mean: 46 years)- , we analyzed the response of 7 taxonomic groups to management abandonment. The meta-analysis demonstrates that forestry affects total richness of saproxylic taxa worldwide, which is verified in our national dataset. However, management abandonment per se is not always the best explanation of the differences between managed and unmanaged forests, but other variables, notably linked to deadwood, better explain the observed patterns for saproxylic groups. For other taxa, the response is weaker and depends more on structural features than on management abandonment. In terms of policy, our project has allowed methodological advances thanks to the development of inventory and remote sensing protocols, as well as statistical methods. The dataset we have gathered is also a first comparison of structure and biodiversity between strict forest reserves and managed forests for France. This network may therefore constitute a first basis for long term biodiversity monitoring in French forests

GNB: Projet de recherche finalisée à l’interface recherche-gestion et ses interactions avec BGF

La gestion durable des forêts repose largement sur la biodiversité dont le fonctionnement reste cependant encore très insuffisamment connu. Il en découle la nécessité d’améliorer, de manière générale, le socle de connaissances relatif à la biodiversité et, plus particulièrement, d’analyser les interactions entre changement climatique, productivité forestière et biodiversité en forêt. Par ailleurs, les stratégies et décisions des acteurs influent sur ces interactions et constituent également des objets d’étude à privilégier. C’est pourquoi le programme de recherche « Biodiversité, gestion forestière et politiques publiques » a lancé en 2013 un appel à projets de recherche avec deux entrées : - l’une par les sciences de la nature axée sur le changement climatique, les mesures de gestion et la dynamique de la biodiversité dans les écosystèmes ; - l’autre par les sciences humaines et sociales sur les stratégies et décisions des acteurs, la gouvernance et les politiques publiques correspondant à la première entrée. Le présent colloque a pour objectifs de : - présenter les résultats des cinq projets de recherche qui ont été sélectionnés à cette occasion sur chacune des deux entrées en les accompagnant en tant que de besoin de regards complémentaires et en illustrant l’un des projets par une visite sur le terrain ; - initier une réflexion sur le progrès des connaissances dans ce domaine, en s’inspirant du devenir de projets antérieurs et en identifiant les principales lacunes à combler. Il se déroulera en trois sessions, chacune introduite par des exposés d’une quinzaine de minutes et conclue par une table ronde permettant un débat avec les participants et les invités

Typical features of Parkinson disease and diagnostic challenges with microdeletion 22q11.2

Objective: To delineate the natural history, diagnosis, and treatment response of Parkinson disease (PD) in individuals with 22q11.2 deletion syndrome (22q11.2DS), and to determine if these patients differ from those with idiopathic PD. Methods: In this international observational study, we characterized the clinical and neuroimaging features of 45 individuals with 22q11.2DS and PD (mean follow-up 7.5 ± 4.1 years). Results: 22q11.2DS PD had a typical male excess (32 male, 71.1%), presentation and progression of hallmark motor symptoms, reduced striatal dopamine transporter binding with molecular imaging, and initial positive response to levodopa (93.3%). Mean age at motor symptom onset was relatively young (39.5 ± 8.5 years); 71.4% of cases had early-onset PD (<45 years). Despite having a similar age at onset, the diagnosis of PD was delayed in patients with a history of antipsychotic treatment compared with antipsychotic-naive patients (median 5 vs 1 year, p = 0.001). Preexisting psychotic disorders (24.5%) and mood or anxiety disorders (31.1%) were common, as were early dystonia (19.4%) and a history of seizures (33.3%). Conclusions: Major clinical characteristics and response to standard treatments appear comparable in 22q11.2DS-associated PD to those in idiopathic PD, although the average age at onset is earlier. Importantly, treatment of preexisting psychotic illness may delay diagnosis of PD in 22q11.DS patients. An index of suspicion and vigilance for complex comorbidity may assist in identifying patients to prioritize for genetic testing

Acute and constitutive increases in central serotonin levels reduce social play behaviour in peri-adolescent rats

Item does not contain fulltextRATIONALE: Serotonin is an important modulator of social behaviour. Individual differences in serotonergic signalling are considered to be a marker of personality that is stable throughout lifetime. While a large body of evidence indicates that central serotonin levels are inversely related to aggression and sexual behaviour in adult rats, the relationship between serotonin and social behaviour during peri-adolescence has hardly been explored. OBJECTIVE: To study the effect of acute and constitutive increases in serotonin neurotransmission on social behaviour in peri-adolescent rats. MATERIALS AND METHODS: Social behaviour in peri-adolesent rats (28-35 days old) was studied after genetic ablation of the serotonin transporter, causing constitutively increased extra-neuronal serotonin levels, and after acute treatment with the serotonin reuptake inhibitor fluoxetine or the serotonin releasing agent 3,4-methylenedioxymethamphetamine (MDMA). A distinction was made between social play behaviour that mainly occurs during peri-adolescence, and non-playful social interactions that are abundant during the entire lifespan of rats. RESULTS: In serotonin transporter knockout rats, social play behaviour was markedly reduced, while non-playful aspects of social interaction were unaffected. Acute treatment with fluoxetine or MDMA dose-dependently inhibited social play behaviour. MDMA also suppressed non-playful social interaction but at higher doses than those required to reduce social play. Fluoxetine did not affect non-playful social interaction. CONCLUSIONS: These data show that both acute and constitutive increases in serotonergic neurotransmission reduce social play behaviour in peri-adolescent rats. Together with our previous findings of reduced aggressive and sexual behaviour in adult serotonin transporter knockout rats, these data support the notion that serotonin modulates social behaviour in a trait-like manner

Glycoinositolphospholipids from Leishmania braziliensis and L. infantum: Modulation of Innate Immune System and Variations in Carbohydrate Structure

The essential role of the lipophosphoglycan (LPG) of Leishmania in innate immune response has been extensively reported. However, information about the role of the LPG-related glycoinositolphospholipids (GIPLs) is limited, especially with respect to the New World species of Leishmania. GIPLs are low molecular weight molecules covering the parasite surface and are similar to LPG in sharing a common lipid backbone and a glycan motif containing up to 7 sugars. Critical aspects of their structure and functions are still obscure in the interaction with the vertebrate host. In this study, we evaluated the role of those molecules in two medically important South American species Leishmania infantum and L. braziliensis, causative agents of visceral (VL) and cutaneous Leishmaniasis (CL), respectively. GIPLs derived from both species did not induce NO or TNF-α production by non-primed murine macrophages. Additionally, primed macrophages from mice (BALB/c, C57BL/6, TLR2−/− and TLR4−/−) exposed to GIPLs from both species, with exception to TNF-α, did not produce any of the cytokines analyzed (IL1-β, IL-2, IL-4, IL-5, IL-10, IL-12p40, IFN-γ) or p38 activation. GIPLs induced the production of TNF-α and NO by C57BL/6 mice, primarily via TLR4. Pre incubation of macrophages with GIPLs reduced significantly the amount of NO and IL-12 in the presence of IFN-γ or lipopolysaccharide (LPS), which was more pronounced with L. braziliensis GIPLs. This inhibition was reversed after PI-specific phospholipase C treatment. A structural analysis of the GIPLs showed that L. infantum has manose rich GIPLs, suggestive of type I and Hybrid GIPLs while L. braziliensis has galactose rich GIPLs, suggestive of Type II GIPLs. In conclusion, there are major differences in the structure and composition of GIPLs from L. braziliensis and L. infantum. Also, GIPLs are important inhibitory molecules during the interaction with macrophages

Neutrino Physics with JUNO

The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multi-purposeunderground liquid scintillator detector, was proposed with the determinationof the neutrino mass hierarchy as a primary physics goal. It is also capable ofobserving neutrinos from terrestrial and extra-terrestrial sources, includingsupernova burst neutrinos, diffuse supernova neutrino background, geoneutrinos,atmospheric neutrinos, solar neutrinos, as well as exotic searches such asnucleon decays, dark matter, sterile neutrinos, etc. We present the physicsmotivations and the anticipated performance of the JUNO detector for variousproposed measurements. By detecting reactor antineutrinos from two power plantsat 53-km distance, JUNO will determine the neutrino mass hierarchy at a 3-4sigma significance with six years of running. The measurement of antineutrinospectrum will also lead to the precise determination of three out of the sixoscillation parameters to an accuracy of better than 1\%. Neutrino burst from atypical core-collapse supernova at 10 kpc would lead to ~5000inverse-beta-decay events and ~2000 all-flavor neutrino-proton elasticscattering events in JUNO. Detection of DSNB would provide valuable informationon the cosmic star-formation rate and the average core-collapsed neutrinoenergy spectrum. Geo-neutrinos can be detected in JUNO with a rate of ~400events per year, significantly improving the statistics of existing geoneutrinosamples. The JUNO detector is sensitive to several exotic searches, e.g. protondecay via the $p\to K^++\bar\nu$ decay channel. The JUNO detector will providea unique facility to address many outstanding crucial questions in particle andastrophysics. It holds the great potential for further advancing our quest tounderstanding the fundamental properties of neutrinos, one of the buildingblocks of our Universe

Dependance en impulsion transverse de la production du J/#psi# dans les interactions p-U, &quot;1&quot;6O-U et &quot;3&quot;2S-U a 200 GeV/c par nucleon

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 77823 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

J. Presse, porte-parole de la presse d'initiative jeune

Le Centre de documentation et d'information lycéen, créé en 1981 et rebaptisé J. Presse en 1989, est une association nationale de la presse d'initiative jeune. Elle fédère, à travers des antennes régionales, près de cinq cents journaux de jeunes , et œuvre pour leur reconnaissance, leur développement et la défense de la liberté d'expression. A l'origine, J. Presse a soutenu les journaux publiés dans le milieu scolaire avant de se tourner vers des publications de quartier. Un bilan quantitatif et qualitatif de cette presse jeune, très dynamique et très mouvante...Drapier Olivier. J. Presse, porte-parole de la presse d'initiative jeune. In: Hommes et Migrations, n°1203, novembre 1996. Intégration et politique de la ville. pp. 45-48

Etude des distributions en impulsion transverse des dimuons produits dans les collisions noyau-noyau auprès du SPS du CERN

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