114 research outputs found
A summary of the beatwave experiments at Ecole Polytechnique
We present a summary of the beatwave particle acceleration program developed
at Ecole Polytechnique. In dedicated experiments, plasma formation, plasma wave
generation and saturation, and particle acceleration were successively studied
and understood in detail. A maximum energy gain of 1.3 MeV was obtained, which
is compatible with an accelerating gradient of 0.7 GV/m.Comment: 3 pages, 4 figure
Experimental Study of electron acceleration by plasma beat-waves with Nd lasers
International audienceWe have observed the acceleration of electrons by a beat-wave generated in a deuterium plasma by two Nd-YAG and Nd-YLF laser wavelengths. Electrons injected at an energy of 3.3 MeV are observed to be accelerated up to 4.7 MeV after the plasma. The energy gain is compatible with a peak electric field of the order of 1.2 GV/m. The experiment has been performed with different injection energies, from 2.5 to 3.3 MeV, with different plasma dimensions, and with different laser intensitie
Fast electron transport and heating in solid-density matter
Two experiments have been performed to investigate heating
by high-intensity laser-generated electrons, in the context of
studies of the fast ignitor approach to inertial confinement fusion
(ICF). A new spectrometer and layered targets have been used to detect
Kα emission from aluminum heated by a fast electron beam.
Results show that a temperature of about 40 eV is reached in solid
density aluminum up to a depth of about 100 ÎĽm
Towards the european strategy for particle physics: The briefing book
This document was prepared as part of the briefing material for the Workshop
of the CERN Council Strategy Group, held in DESY Zeuthen from 2nd to 6th May
2006. It gives an overview of the physics issues and of the technological
challenges that will shape the future of the field, and incorporates material
presented and discussed during the Symposium on the European Strategy for
Particle Physics, held in Orsay from 30th January to 2nd February 2006,
reflecting the various opinions of the European community as recorded in
written submissions to the Strategy Group and in the discussions at the
Symposium
Regulation of GIP and GLP1 Receptor Cell Surface Expression by N-Glycosylation and Receptor Heteromerization
In response to a meal, Glucose-dependent Insulinotropic Polypeptide (GIP) and Glucagon-like Peptide-1 (GLP-1) are released from gut endocrine cells into the circulation and interact with their cognate G-protein coupled receptors (GPCRs). Receptor activation results in tissue-selective pleiotropic responses that include augmentation of glucose-induced insulin secretion from pancreatic beta cells. N-glycosylation and receptor oligomerization are co-translational processes that are thought to regulate the exit of functional GPCRs from the ER and their maintenance at the plasma membrane. Despite the importance of these regulatory processes, their impact on functional expression of GIP and GLP-1 receptors has not been well studied. Like many family B GPCRs, both the GIP and GLP-1 receptors possess a large extracellular N-terminus with multiple consensus sites for Asn-linked (N)-glycosylation. Here, we show that each of these Asn residues is glycosylated when either human receptor is expressed in Chinese hamster ovary cells. N-glycosylation enhances cell surface expression and function in parallel but exerts stronger control over the GIP receptor than the GLP-1 receptor. N-glycosylation mainly lengthens receptor half-life by reducing degradation in the endoplasmic reticulum. N-glycosylation is also required for expression of the GIP receptor at the plasma membrane and efficient GIP potentiation of glucose-induced insulin secretion from the INS-1 pancreatic beta cell line. Functional expression of a GIP receptor mutant lacking N-glycosylation is rescued by co-expressed wild type GLP1 receptor, which, together with data obtained using Bioluminescence Resonance Energy Transfer, suggests formation of a GIP-GLP1 receptor heteromer
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