785 research outputs found
High current operation of pre-bunching cavities in the CT3 accelerator
CDROM (JACoW)In the framework of the CLIC studies for a 3 TeV centre of mass linear collider the CLIC Test Facility-3 accelerator (CTF3) is developed to validate the novel concept of CLIC drive beam generation. The front end of the CTF3 linac uses a 140 kV thermionic gun capable to deliver a beam with currents of up to 10 A during 1.5 microseconds. TheĂ time structure of this beam is generated with two standing wave single-cell 3 GHz pre-buncher cavities. The high current demands special care in the design of the pre-bunchers to preserve beam quality and transmission. A particular concern was beamloading in the second pre-buncher. In this paper, the design and the conditioning of the pre-bunchers are reported but the main focus is on the commissioning with the electron beam, which showed unexpected results. Indeed, contrary to our expectations, the unbunched beam seems to induce a kind of beamloading in the first pre-buncher while the second one shows none
Computing FO-Rewritings in EL in Practice: from Atomic to Conjunctive Queries
A prominent approach to implementing ontology-mediated queries (OMQs) is to
rewrite into a first-order query, which is then executed using a conventional
SQL database system. We consider the case where the ontology is formulated in
the description logic EL and the actual query is a conjunctive query and show
that rewritings of such OMQs can be efficiently computed in practice, in a
sound and complete way. Our approach combines a reduction with a decomposed
backwards chaining algorithm for OMQs that are based on the simpler atomic
queries, also illuminating the relationship between first-order rewritings of
OMQs based on conjunctive and on atomic queries. Experiments with real-world
ontologies show promising results
Computable randomness is about more than probabilities
We introduce a notion of computable randomness for infinite sequences that
generalises the classical version in two important ways. First, our definition
of computable randomness is associated with imprecise probability models, in
the sense that we consider lower expectations (or sets of probabilities)
instead of classical 'precise' probabilities. Secondly, instead of binary
sequences, we consider sequences whose elements take values in some finite
sample space. Interestingly, we find that every sequence is computably random
with respect to at least one lower expectation, and that lower expectations
that are more informative have fewer computably random sequences. This leads to
the intriguing question whether every sequence is computably random with
respect to a unique most informative lower expectation. We study this question
in some detail and provide a partial answer
Infliximab therapy in rheumatoid arthritis and ankylosing spondylitis-induced specific antinuclear and antiphospholipid autoantibodies without autoimmune clinical manifestations: a two-year prospective study
Treatment of rheumatoid arthritis (RA) with infliximab (Remicade(Âź)) has been associated with the induction of antinuclear autoantibodies (ANA) and anti-double-stranded DNA (anti-dsDNA) autoantibodies. In the present study we investigated the humoral immune response induced by infliximab against organ-specific or non-organ-specific antigens not only in RA patients but also in patients with ankylosing spondylitis (AS) during a two-year followup. The association between the presence of autoantibodies and clinical manifestations was then examined. The occurrence of the various autoantibodies was analyzed in 24 RA and 15 AS patients all treated with infliximab and in 30 RA patients receiving methotrexate but not infliximab, using the appropriate methods of detection. Infliximab led to a significant induction of ANA and anti-dsDNA autoantibodies in 86.7% and 57% of RA patients and in 85% and 31% of AS patients, respectively. The incidence of antiphospholipid (aPL) autoantibodies was significantly higher in both RA patients (21%) and AS patients (27%) than in the control group. Most anti-dsDNA and aPL autoantibodies were of IgM isotype and were not associated with infusion side effects, lupus-like manifestations or infectious disease. No other autoantibodies were shown to be induced by the treatment. Our results confirmed the occurrence of ANA and anti-dsDNA autoantibodies and demonstrated that the induction of ANA, anti-dsDNA and aPL autoantibodies is related to infliximab treatment in both RA and AS, with no significant relationship to clinical manifestations
Mechanical behavior of nickel base foams for diesel particle filter applications
International audienceAn original processing route by powder metallurgy was developped to alloy pure Ni foams so, that the foam becomes refractory for high temperature applications. The modelling of such a foam at high temperature starts from the behavior of the basic constitutive material, then we use micromechanical models to predict the mechanical properties under tension and in compression creep. A 3D finite element analysis of a volume analysed by X-ray tomography is performed to study the foam deformation mechanisms in both conditions
On the succinctness of query rewriting over shallow ontologies
We investigate the succinctness problem for conjunctive query rewritings over OWL2QL ontologies of depth 1 and 2 by means of hypergraph programs computing Boolean functions. Both positive and negative results are obtained. We show that, over ontologies of depth 1, conjunctive queries have polynomial-size nonrecursive datalog rewritings; tree-shaped queries have polynomial positive existential rewritings; however, in the worst case, positive existential rewritings can be superpolynomial. Over ontologies of depth 2, positive existential and nonrecursive datalog rewritings of conjunctive queries can suffer an exponential blowup, while first-order rewritings can be superpolynomial unless NP ïżœis included in P/poly. We also analyse rewritings of tree-shaped queries over arbitrary ontologies and note that query entailment for such queries is fixed-parameter tractable
PHIL: a Test Beam line at LAL
WEPP078International audienceIn the framework of a European contract*, LAL is in charge of the construction of one photo-injector for the drive beam linac of the CLIC Test Facility 3 [1] at CERN. This contract together with national funds allowed LAL to build a home test accelerator, PHIL, with the same photo-injector as for CTF3. The goal is to undergo experiments on the design and technology of advanced RF guns, to develop diagnostics and feedback techniques, a part of the beam time will be also shared with users of the electron beam. So far, the construction of this accelerator at LAL was very much delayed because of the legal obligation to upgrade the radiation shielding in agreement with the actual radiation safety thresholds. The required civil engineering is now finished and the installation of the components is under way. We will first present a design of the accelerator and few dynamic simulation results. Finally we will give an up to date status of the accelerator construction
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