排序方式: 共有18条查询结果,搜索用时 15 毫秒
1.
D. Bisello G. Busetto A. Castro M. Nigro M. Penzo L. Pescara M. Posocco P. Sartori L. Stanco Z. Ajaltouni A. Falvard J. Jousset B. Michel J. C. Montret A. Antonelli R. Baldini A. Calcaterra G. Capon M. Schioppa J. -E. Augustin G. Cosme F. Couchot B. Dudelzak F. Fulda G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne V. Lepeltier F. Manè C. Paulot R. Riskalla Ph. Roy G. Szklarz DM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,39(1):13-19
Thee + e ?→K + K ? cross section has been measured from about 750 events in the energy interval \(1350 \leqq \sqrt s \leqq 2400 MeV\) with the DM2 detector at DCI. TheK ± form factor |F F ±| cannot be explained by the ρ, ω, ? and ρ′(1600). An additional resonant amplitude at 1650 MeV has to be added as suggested by a previous experiment. 相似文献
2.
3.
4.
J. -E. Augustin G. Cosme F. Couchot B. Dudelzak F. Fulda B. Grelaud G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne V. Lepeltier B. Louis F. Mané C. Paulot R. Riskalla Ph. Roy F. Rumpf G. Szklarz Z. Ajaltouni A. Falvard J. Jousset B. Michel J. C. Montret R. Baldini S. Calcaterra G. Capon D. Bisello G. Busetto S. Limentani M. Nigro L. Pescara M. Posocco P. Sartori L. Stanco DM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,36(3):369-376
The radiative decayJ/ψ → γ π+ π? has been studied using the 8.6 millionJ/ψ produced in the DM2 experiment at the DCIe +e? storage rings at Orsay. The π+ π? mass spectrum shows a cleanf 2 (1270) signal, and the possible presence of two other states at thef 2 (1720) andf 4 (2030) masses. For thef 2 (1270), the branching ratio BR(J/ψ →γf)xBR(f→π+ π?) is measured to be (7.50±0.30±1.12)×10?4, and the spin analysis prefers theJ=2 assignment, with helicity parametersx=0.83±0.06 andy=0.01±0.06. The existence of higher mass states is discussed. 相似文献
5.
The steady propagation of a thin smouldering front in a half-spacehas been considered. A suitable coordinate transformation hasallowed the region near the leading edge of the front to beexamined for both a maintained planar surface and with surfacecollapse due to material shrinkage. The change in the oxidizerconcentration for a small increment in the propagation speedfor large time and surface collapse has been determined. Theinfluence of two types of nonlinear diffusion on the shape ofthe smouldering front has been found; other cases can be dealtwith in a similar manner. 相似文献
6.
D. A. Shapiro H. N. Chapman D. DePonte R. B. Doak P. Fromme G. Hembree M. Hunter S. Marchesini K. Schmidt J. Spence D. Starodub U. Weierstall 《Journal of synchrotron radiation》2008,15(6):593-599
Atomic‐resolution structures from small proteins have recently been determined from high‐quality powder diffraction patterns using a combination of stereochemical restraints and Rietveld refinement [Von Dreele (2007), J. Appl. Cryst. 40 , 133–143; Margiolaki et al. (2007), J. Am. Chem. Soc. 129 , 11865–11871]. While powder diffraction data have been obtained from batch samples of small crystal‐suspensions, which are exposed to X‐rays for long periods of time and undergo significant radiation damage, the proof‐of‐concept that protein powder diffraction data from nanocrystals of a membrane protein can be obtained using a continuous microjet is shown. This flow‐focusing aerojet has been developed to deliver a solution of hydrated protein nanocrystals to an X‐ray beam for diffraction analysis. This method requires neither the crushing of larger polycrystalline samples nor any techniques to avoid radiation damage such as cryocooling. Apparatus to record protein powder diffraction in this manner has been commissioned, and in this paper the first powder diffraction patterns from a membrane protein, photosystem I, with crystallite sizes of less than 500 nm are presented. These preliminary patterns show the lowest‐order reflections, which agree quantitatively with theoretical calculations of the powder profile. The results also serve to test our aerojet injector system, with future application to femtosecond diffraction in free‐electron X‐ray laser schemes, and for serial crystallography using a single‐file beam of aligned hydrated molecules. 相似文献
7.
Silbernagel K Jechorek R Barbour WM Mrozinski P Alejo W Aleo V Andaloro B Beacorn F Benzinger J Bogar S Brayman C Broom J Carson M Carver C Cheng C Centrella B Clayborn J Collins C Deibel C Divine M Eliasberg S Farmer D Frye S Gatesy T Goodstein E Halker C Hall G Hanson P Hartman G Heddaeus K Hembree J Hutchins J Istafanos P Jechorek R Jenkins J Kerdahi K Kremer S Lal A Leighton S Lester D Lewis J Lin J Martin J Maselli M McCarthy P McGovern B Mills M Mohnke F Moon B Moss D Plaza M Robeson S 《Journal of AOAC International》2004,87(2):395-410
A multilaboratory study was conducted to compare the automated BAX system and the standard cultural methods for detection of Listeria monocytogenes in foods. Six food types (frankfurters, soft cheese, smoked salmon, raw, ground beef, fresh radishes, and frozen peas) were analyzed by each method. For each food type, 3 inoculation levels were tested: high (average of 2 CFU/g), low (average of 0.2 CFU/g) and uninoculated controls. A total of 25 laboratories representing government and industry participated. Of the 2335 samples analyzed, 1109 were positive by the BAX system and 1115 were positive by the standard method. A Chi square analysis of each of the 6 food types, at the 3 inoculation levels tested, was performed. For all foods, except radishes, the BAX system performed as well as or better than the standard reference methods based on the Chi square results. 相似文献
8.
9.
10.
D. Starodub P. Rez G. Hembree M. Howells D. Shapiro H. N. Chapman P. Fromme K. Schmidt U. Weierstall R. B. Doak J. C. H. Spence 《Journal of synchrotron radiation》2008,15(1):62-73
The resolution of X‐ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed serial crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single‐file train across a continuous X‐ray beam, and resolution is then limited only by the available molecular and X‐ray fluxes and molecular alignment. Orientation of the diffracting molecules is achieved by laser alignment. The incident X‐ray fluence (energy/area) is evaluated that is required to obtain a given resolution from (i) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (ii) explicit simulation of diffraction patterns for a GroEL–GroES protein complex, and (iii) the spatial frequency cut‐off of the transfer function following iterative solution of the phase problem, and reconstruction of an electron density map in the projection approximation. These calculations include counting shot noise and multiple starts of the phasing algorithm. The results indicate counting time and the number of proteins needed within the beam at any instant for a given resolution and X‐ray flux. An inverse fourth‐power dependence of exposure time on resolution is confirmed, with important implications for all coherent X‐ray imaging. It is found that multiple single‐file protein beams will be needed for sub‐nanometer resolution on current third‐generation synchrotrons, but not on fourth‐generation designs, where reconstruction of secondary protein structure at a resolution of 7 Å should be possible with relatively short exposures. 相似文献