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Dutz H Helbing K Krimmer J Speckner T Zeitler G Ahrens J Altieri S Annand JR Anton G Arends HJ Beck R Bock A Bradtke C Braghieri A v Drachenfels W Frommberger F Godo M Goertz S Grabmayr P Hasegawa S Hansen K Harmsen J Heid E Hillert W Holvoet H Horikawa N Iwata T Van Hoorebeke L d'Hose N Jennewein P Kiel B Klein F Kondratiev R Lang M Lannoy B Leukel R Lisin V Menze D Meyer W Michel T Naumann J Panzeri A Pedroni P Pinelli T Preobrajenski I Radtke E Reicherz G Rohlof C Rostomyan T Sauer M 《Physical review letters》2003,91(19):192001
To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] microb. 相似文献
3.
We address the problem of the separation of variables for the Hamilton–Jacobi equation within the theoretical scheme of bi-Hamiltonian geometry. We use the properties of a special class of bi-Hamiltonian manifolds, called N manifolds, to give intrisic tests of separability (and Stäckel separability) for Hamiltonian systems. The separation variables are naturally associated with the geometrical structures of the N manifold itself. We apply these results to bi-Hamiltonian systems of the Gel'fand–Zakharevich type and we give explicit procedures to find the separated coordinates and the separation relations. 相似文献
4.
P. Pedroni 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):401-404
First measurements of pion photoproduction using circularly polarized photons on longitudinally polarized protons were carried out at MAMI (Mainz) in the energy range
-800 MeV. Results of the helicity dependence of the total inclusive photoabsorption cross-section and of the pion photoproduction channels will be presented. These data provide new input for multipole analyses and determine the main contribution to the Gerasimov-Drell-Hearn integral and the forward spin polarizability
.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.60.Le Meson production - 14.20.Gk Baryon resonances with S = 0P. Pedroni: For the GDH and A2 Collaborations 相似文献
5.
V. Pedroni P. C. Schulz M. E. Gschaider de Ferreira M. A. Morini 《Colloid and polymer science》2000,278(10):964-971
We synthesised a porous siliceous material via hydrothermal hydrolysis of sodium silicate, using chitosan as a template.
As far as we know, this is the first synthesis of siliceous porous material using chitosan as a template in a hydrothermal
way. A fibrous material was obtained, whose macroscopic fibres were formed by a spongelike siliceous network with pores having
a radius of 0.57 μm. The siliceous walls of the pores were, in turn, of the form of a microporous–mesoporous material; the
pore radius distribution was polymodal with maxima at 0.84, 1.0, 1.2 and 1.5 nm and a broad band between 3 and 10 nm. This
structure may be due to the aggregation of the hydrated chitosan helices in bundles of parallel fibres with different size
and the gelation of the system. The aggregation process might be induced by the addition of silicate.
Received: 12 January 2000/Accepted: 7 March 2000 相似文献
6.
In this paper we review a recently introduced method for solving the Hamilton-Jacobi equations by the method of Separation of Variables. This method is based on the notion of pencil of Poisson brackets and on the bihamiltonian approach to integrable systems. We discuss how separability conditions can be intrinsically characterized within such a geometrical set-up, the definition of the separation coordinates being encompassed in the bihamiltonian structure itself. We finally discuss these constructions studying in details a particular example, based on a generalization of the classical Toda Lattice. 相似文献
7.
J. Ahrens S. Altieri J. R. M. Annand H. -J. Arends R. Beck A. Braghieri N. d'Hose H. Dutz S. Goertz P. Grabmayr S. Hasegawa E. Heid H. Holvoet L. Van Hoorebeke N. Horikawa T. Iwata O. Jahn P. Jennewein R. Kondratiev J. Krimmer M. Lang B. Lannoy K. Livingston J. C. McGeorge W. Meyer A. Panzeri P. Pedroni T. Pinelli I. Preobrajenski G. Reicherz G. Rosner M. Rost T. Rostomyan D. Ryckbosch M. Schumacher B. Seitz G. Tamas A. Thomas R. van de Vyver Th. Walcher F. Zapadtka 《The European Physical Journal A - Hadrons and Nuclei》2005,26(1):135-140
The G asymmetry of the γp↦Nπ reaction has been measured for the first time for Eγ = 340±14 MeV. This observable, for which very scarce published data exist, plays an important role to disentangle the contributions
of the various nucleon resonances. The experiment, performed at the Mainz microtron MAMI, used a 4π-detector system, a linearly
polarized, tagged photon beam, and a longitudinally polarized proton target. 相似文献
8.
We show that the Drinfeld-Sokolov reduction can be framed in the general theory of bihamiltonian manifolds, with the help of a specialized version of a reduction theorem for Poisson manifolds by Marsden and Ratiu.This work has been supported by the Italian MURST and by the GNFM of the Italian C.N.R. 相似文献
9.
We introduce a bi-Hamiltonian hierarchy on the loop-algebra of
endowed with a suitable Poisson pair. It gives rise to the usual Camassa–Holm (CH) hierarchy by means of a bi-Hamiltonian reduction, and its first nontrivial flow provides a three-component extension of the CH equation. 相似文献
10.
Viel A Genuardi M Lucci-Cordisco E Capozzi E Rovella V Fornasarig M Ponz de Leòn M Anti M Pedroni M Bellacosa A Percesepe A Covino M Benatti P Del Tin L Roncucci L Valentini M Boiocchi M Neri G 《Community genetics》1998,1(4):229-236
OBJECTIVE: Identification of clinical and molecular characteristics associated with constitutional MLH1 and MSH2 mutations and definition of a stepwise strategy for the selection of colorectal cancer (CRC) patients amenable to MLH1 and MSH2 genetic testing. METHODS: 90 unrelated CRC patients were initially selected on the basis of either familial or early onset occurrence of CRC. They were screened for the presence of constitutional MLH1 and MSH2 mutations and for microsatellite instability (MSI). RESULTS: 16 pathogenetic mutations (9 MLH1 and 7 MSH2) were identified in 41% of Amsterdam hereditary nonpolyposis colorectal cancer (HNPCC) families, 5% of suspected HNPCC families, and 14% of sporadic early-onset CRC patients. The presence of the mutations correlated with MSI, with early age of onset and proximal location of the tumor, and with the presence of some extracolonic tumors of the HNPCC spectrum and/or multiple tumors in the family. CONCLUSIONS: Evaluation of clinical and molecular characteristics is useful for the identification of candidates to MLH1 and MSH2 mutational analysis and allows the application of a rational approach to genetic testing. 相似文献