3,683 research outputs found

    Acylsulfonamide safety-catch linker : promise and limitations for solid-phase oligosaccharide synthesis

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    Safety-catch linkers are useful for solid-phase oligosaccharide synthesis as they are orthogonal to many common protective groups. A new acylsulfonamide safety-catch linker was designed, synthesized and employed during glycosylations using an automated carbohydrate synthesizer. The analysis of the cleavage products revealed shortcomings for oligosaccharide synthesis

    Unidirectional light emission from high-Q modes in optical microcavities

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    We introduce a new scheme to design optical microcavities supporting high-Q modes with unidirectional light emission. This is achieved by coupling a low-Q mode with unidirectional emission to a high-Q mode. The coupling is due to enhanced dynamical tunneling near an avoided resonance crossing. Numerical results for a microdisk with a suitably positioned air hole demonstrate the feasibility and the potential of this concept.Comment: 4 pages, 6 figures (in reduced resolution

    GePEToS : A Geant4 Monte Carlo simulation package for Positron Emission Tomography

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    GePEToS is a simulation framework developed over the last few years for assessing the instrumental performance of future PET scanners. It is based on Geant4, written in Object-Oriented C++ and runs on Linux platforms. The validity of GePEToS has been tested on the well-known Siemens ECAT EXACT HR+ camera. The results of two application examples are presented : the design optimization of a liquid Xe micro-PET camera dedicated to small animal imaging as well as the evaluation of the effect of a strong axial magnetic field on the image resolution of a Concorde P4 micro-PET camera.Comment: 5 pages, 12 figures, submitted to IEEE Transactions on Nuclear Scienc

    Experimental study of a liquid Xenon PET prototype module

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    A detector using liquid Xenon in the scintillation mode is studied for Positron Emission Tomography (PET). The specific design aims at taking full advantage of the liquid Xenon properties. It does feature a promising insensitive to any parallax effect. This work reports on the performances of the first LXe prototype module, equipped with a position sensitive PMT operating in the VUV range (178 nm).Comment: Proc. of the 7th International Workshops on Radiation Imaging Detectors (IWORID-7), Grenoble, France 4-7 July 200

    Premiers résultats des plongées Nautile de la campagne SUBPSO 1 sur la zone de collision "ride des Loyauté arc des Nouvelles-Hébrides" (Sud-Ouest Pacifique)

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    International audienceFour dives were conducted over the collision zone "Loyalty ridge/New Hebrides arc". On the Loyalty ridge, basaltic and rhyolitic breccias overlain by reef limestones were observed. An andesitic volcaniclastic sequence outcrops on the western flank of the New Hebrides arc. Near the trench, the Loyalty ridge has been sliced by normal faults along which the reef limestones collapsed of at least 4,000m. The unusual existence ofSW verging anticlines on the outer wall, 1,000m above the trench, was confirmed. These folds affect rocks ofthe lowerpartofthe ridge flank.Quatre plongĂ©es, rĂ©alisĂ©es sur la zone de collision «ride des LoyautĂ©/arc des NouvellesHĂ©brides », ont permis d'observer: (1) sur la ride des LoyautĂ©, en mur externe de la fosse, des formations volcano-dĂ©tritiques basaltiques et rhyolitiques, coiffĂ©es par des calcaires rĂ©cifaux, le toutintensĂ©ment fracturĂ©; (2) sur le flanc occidental de l'arc nĂ©o-hĂ©bridais, en mur interne de la fosse, une sĂ©rie volcano-dĂ©tritique andĂ©sitique. A l'approche de la fosse, des failles normales ont dĂ©coupĂ© la ride des LoyautĂ©, amenant les calcaires rĂ©cifaux jusqu'Ă  des profondeurs de plus de 4000m. Enfin, la prĂ©sence inhabituelle de plis dĂ©jetĂ©s vers le SW sur le mur externe, 1000 m au-dessus de la fosse, a Ă©tĂ© confirmĂ©e; ils semblent s'ĂȘtre dĂ©veloppĂ©s aux dĂ©pens de matĂ©riel de la partie infĂ©rieure du flanc de la ride

    The FFAG R&D and medical application project RACCAM

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    JACoW web site http://accelconf.web.cern.ch/AccelConf/e06/Pre-Press/WEPCH161.pdf WEPCH161International audienceThe RACCAM project (Recherche en ACCelerateurs et Applications Medicales) has recently obtained fundings, extending over three years (2006-2008), from the French National Research Agency (ANR). RACCAM is a tripartite collaboration, involving (i) the CNRS Laboratory IN2P3/LPSC, (ii) the French magnet industrial SIGMAPHI, and (iii) the nuclear medecine Departement of Grenoble Hospital. The project concerns fixed field alternating gradient accelerator (FFAG) research on the one hand, and on the other hand their application as hadrontherapy and biology research machines. RACCAM's goal is three-fold, (i) participate to the on-going international collaborations in the field of FFAGs and recent concepts of "non-scaling" FFAGs, with frames for instance, the Neutrino Factory (NuFact) and the EMMA project of an electron model of a muon FFAG accelerator, (ii) design, build and experiment a prototype of an FFAG magnet proper to fulfil the requirements of rapid cycling acceleration, (iii) develop the concepts, and show the feasibility, of the application of such FFAG beams to hadrontherapy and to biology research