A Robust Logical and Computational Characterisation of Peer-to-Peer Database Systems

In this paper we give a robust logical and computational characterisation of peer-to-peer (p2p) database systems. We first define a precise model-theoretic semantics of a p2p system, which allows for local inconsistency handling. We then characterise the general computational properties for the problem of answering queries to such a p2p system. Finally, we devise tight complexity bounds and distributed procedures for the problem of answering queries in few relevant special cases

Chemical shift imaging from simultaneous acquisition of a primary and a stimulated echo

An imaging method is presented for obtaining chemical shift images from only one acquisition. Images are acquired with the same spatial resolution as in regular spin-echo imaging. The sequence is based on the simultaneous acquisition of a spin echo and a stimulated echo in a single pass. The use of 90 degrees radiofrequency pulse flip angles results in the same proton density, T2 and T1 weighting for the two echoes. Application of this sequence to chemical shift imaging is discussed for three fat suppression techniques (chopper, CHESS, and hybrid). Imaging was performed on phatoms and volunteers. The image quality was the same as those obtained by the chopper and the hybrid methods and the acquisition time was reduced by a factor of two

Knowledge Representation with Ontologies: The Present and Future

Recently, we have seen an explosion of interest in ontologies as artifacts to represent human knowledge and as critical components in knowledge management, the semantic Web, business-to-business applications, and several other application areas. Various research communities commonly assume that ontologies are the appropriate modeling structure for representing knowledge. However, little discussion has occurred regarding the actual range of knowledge an ontology can successfully represent

Idazoxan does not prevent but worsens focal hypoxic-ischemic brain damage in neonatal Wistar rats

We examined the neuroprotective efficacy of a post-treatment with idazoxan (Idaz): an alpha2-adrenoceptor antagonist with activity at the I1- and I2-subtypes of the imidazoline receptor (I-receptor), in an experimental model of perinatal hypoxic-ischemic (HI) brain damage. Seventy-two, 7-day-old Wistar rats were subjected to permanent unilateral ligation of the common carotid artery and transient (2 hr) hypoxia (8% O(2)). The surviving animals were sub-divided into 3 groups: one "control" group received intraperitoneal (i.p.) injection of saline (Sigma; n = 21) and two "treated" groups received, 10 min post-HI, i.p. treatments with Idaz (I3: 3 mg/kg; n = 19) or (I8: 8 mg/kg; n = 20). Idaz effects were assessed by TTC-staining 72 hr post-HI for Sigma (n = 13), I3 (n = 11), and I8 (n = 12) groups and by MRI-examination 5 weeks post-HI for Sigma (n = 8), I3 (n = 8), and I8 (n = 6) groups. Total ratio of brain infarct areas were significantly (P < 0.01) different between Sigma and Idaz-treated rats: 20.9 +/- 4.0%, 35.6 +/- 5.9 % and 36.8 +/- 5.8% for Sigma, I3 and I8, respectively, when determined with TTC-staining and; 23.3 +/- 3.7%, 39.8 +/- 4.2%, and 43.2 +/- 10.1%, for Sigma, I3, and I8, respectively, when assessed by MRI. Our results suggest that Idaz, given as a post-HI treatment, does not exert neuroprotective effects but enhances the brain injury induced by focal neonatal cerebral HI. The deleterious mechanism may result from an overactivity of sympathetic tone and/or the immaturity of central I-receptors in newborn rats

Présentation des plateformes SCIAM et IRM-PRIMEX

Présentation des plateformes SCIAM et IRM-PRIMEX Guillaume Mabilleau et Florence Franconi Université d’Angers, Institut de Biologie en Santé, 49933 Angers, France Le service commun d’imageries et d’analyses microscopiques (SCIAM) et la plateforme d’Imagerie par Résonance Magnétique (IRM) préclinique – PRIMEX sont deux services communs de la SFR ICAT 4208 de l’Université d’Angers. Le SCIAM dispose d’un ensemble dispose d’un microtomographe à rayons X (Bruker microCT 1076) permettant l’acquisition in vivo à des résolutions de 9, 18 et 36 µm et d’un irradiateur à rayons X (Faxitron CP-160). La plateforme PRIMEX dispose d’un imageur Biospec 70/20 Avance III (Bruker Biospin) opérant à un champ magnétique de 7 Tesla. Ces équipements sont particulièrement adaptés pour l’imagerie de la souris ou du rat. Un tour d’horizon du potentiel de ces équipements en préclinique sera présenté. Ces équipements permettent des explorations in vivo chez le petit animal pour des applications telles que la caractérisation anatomique ou fonctionnelle de modèle animaux en oncologie, neurologie, cardiologie… ou l’évaluation de l’efficacité de nouveaux traitements thérapeutiques. Des applications dans d’autres domaines sont aussi possibles (végétal, agroalimentaire, matériaux, ex vivo…). Ces deux plateformes sont ouvertes aux partenaires institutionnels et industriels. Elles proposent un accompagnement scientifique et technique à la conception de projets ainsi que des formations dans le domaine de l’IRM préclinique