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101.
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Aubert B Barate R Boutigny D Couderc F Karyotakis Y Lees JP Poireau V Tisserand V Zghiche A Grauges E Palano A Pappagallo M Pompili A Chen JC Qi ND Rong G Wang P Zhu YS Eigen G Ofte I Stugu B Abrams GS Battaglia M Breon AB Brown DN Button-Shafer J Cahn RN Charles E Day CT Gill MS Gritsan AV Groysman Y Jacobsen RG Kadel RW Kadyk J Kerth LT Kolomensky YG Kukartsev G Lynch G Mir LM Oddone PJ Orimoto TJ Pripstein M Roe NA Ronan MT Wenzel WA Barrett M Ford KE Harrison TJ Hart AJ Hawkes CM Morgan SE 《Physical review letters》2007,98(21):211804
We present a measurement of the partial branching fractions and mass spectra of the exclusive radiative penguin processes B-->Kpipigamma in the range m(Kpipi)<1.8 GeV/c(2). We reconstruct four final states: K(+)pi(-)pi(+)gamma, K(+)pi(-)pi(0)gamma, K(S)(0)pi(-)pi(+)gamma, and K(S)(0)pi(+)pi(0)gamma, where K(S)(0)-->pi(+)pi(-). Using 232 x 10(6) e(+)e(-)-->BB events recorded by the BABAR experiment at the SLAC PEP-II asymmetric-energy storage ring, we measure the branching fractions B(B(+)-->K(+)pi(-)pi(+)gamma)=[2.95+/-0.13(stat)+/-0.20(syst)] x 10(-5), B(B(0)-->K(+)pi(-)pi(0)gamma)=[4.07+/-0.22(stat)+/-0.31(syst)] x 10(-5), B(B(0)-->K(0)pi(+)pi(-)gamma)=[1.85+/-0.21(stat)+/-0.12(syst)] x 10(-5), and B(B(+)-->K(0)pi(+)pi(0)gamma)=[4.56+/-0.42(stat)+/-0.31(syst)] x 10(-5). 相似文献
105.
Navasardyan T Adams GS Ahmidouch A Angelescu T Arrington J Asaturyan R Baker OK Benmouna N Bertoncini C Blok HP Boeglin WU Bosted PE Breuer H Christy ME Connell SH Cui Y Dalton MM Danagoulian S Day D Dodario T Dunne JA Dutta D El Khayari N Ent R Fenker HC Frolov VV Gan L Gaskell D Hafidi K Hinton W Holt RJ Horn T Huber GM Hungerford E Jiang X Jones M Joo K Kalantarians N Kelly JJ Keppel CE Kubarovski V Li Y Liang Y Malace S Markowitz P McGrath E McKee P Meekins DG Mkrtchyan H Moziak B 《Physical review letters》2007,98(2):022001
A large data set of charged-pion (pi+/-) electroproduction from both hydrogen and deuterium targets has been obtained spanning the low-energy residual-mass region. These data conclusively show the onset of the quark-hadron duality phenomenon, as predicted for high-energy hadron electroproduction. We construct several ratios from these data to exhibit the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark-->pion production mechanisms. 相似文献
106.
The majority of aquatic vertebrates are suction feeders: by rapidly expanding the mouth cavity they generate a fluid flow
outside of their head in order to draw prey into their mouth. In addition to the biological relevance, the generated flow
field is interesting fluid mechanically as it incorporates high velocities, is localized in front of the mouth, and is unsteady,
typically lasting between 10 and 50 ms. Using manometry and high-speed particle image velocimetry, this is the first study
to quantify pressure within and outside the mouth of a feeding fish while simultaneously measuring the velocity field outside
the mouth. Measurements with a high temporal (2 ms) and spatial (<1 mm) resolution were made for several feeding events of
a single largemouth bass (Micropterus salmoides). General properties of the flow were evaluated, including the transient velocity field, its relationship to pressure within
the mouth and pressure at the prey. We find that throughout the feeding event a relationship exists for the magnitude of fluid
speed as a function of distance from the predator mouth that is based on scaling the velocity field according to the size
of the mouth opening and the magnitude of fluid speed at the mouth. The velocity field is concentrated within an area extending
approximately one mouth diameter from the fish and the generated pressure field is even more local to the mouth aperture.
Although peak suction pressures measured inside the mouth were slightly larger than those that were predicted using the equations
of motion, we find that these equations give a very accurate prediction of the timing of peak pressure, so long as the unsteady
nature of the flow is included. 相似文献
107.
Martin V. Day 《Journal of Dynamics and Differential Equations》1996,8(4):573-601
We discuss the phenomenon of cycling for noise induced escape to a unstable periodic orbit. The presence of cycling is shown to follow from qualitative properties of two quasipotential functions. A method of numerically evaluating these quasipotential functions is described, and applied to the Van der Pol oscillator as an example. Figures resulting from these calculations reveal that nonconvergent cycling of exit measures does occur for the Van der Pol example. 相似文献
108.
Guochuan Yin Suparna Baksi Roy Andrew M. Danby Victor Day John Carter William M. Scheper Daryle H. Busch 《Journal of inclusion phenomena and macrocyclic chemistry》2011,71(3-4):311-318
On the basis of mass spectral studies alone, the relatively new manganese complex, Mn(Et2EBC)Cl2 (Et2EBC = 4,11-diethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane), a homolog of the well proven, peroxide-based laundry bleach, Mn(Me2EBC)Cl2, has been reported to undergo a sequence of 2-electron oxidation steps, ultimately converting its ethyl groups into chelated ethoxo and methylene carboxylato groups, [MnIV{(?OCH2CH2)(?O2CCH2)}EBC)](PF6)2. We report here the isolation and characterization of that unusual product, and provide insight into the remarkable catalytic pathway to its formation. At temperatures above 0 °C, oxidation by aqueous H2O2 reliably transforms Mn(Et2EBC)Cl2 into [MnIV{(?OCH2CH2)(?O2CCH2)}EBC)]2+. The experimental data for this intramolecular ethyl group transformation is consistent with oxygen insertion into a methyl C?CH moiety of the ethyl group, ?CNCH2C(?CH)H2, by the MnIV?COOH functional group. 相似文献
109.
Bonnel D Longuespee R Franck J Roudbaraki M Gosset P Day R Salzet M Fournier I 《Analytical and bioanalytical chemistry》2011,401(1):149-165
The large amount of data generated using matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI)
poses a challenge for data analysis. In fact, generally about 1.108–1.109 values (m/z, I) are stored after a single MALDI-MSI experiment. This imposes processing techniques using dedicated informatics tools
to be used since manual data interpretation is excluded. This work proposes and summarizes an approach that utilizes a multivariable
analysis of MSI data. The multivariate analysis, such as principal component analysis–symbolic discriminant analysis, can
remove and highlight specific m/z from the spectra in a specific region of interest. This approach facilitates data processing and provides better reproducibility,
and thus, broadband acquisition for MALDI-MSI should be considered an effective tool to highlight biomarkers of interest.
Additionally, we demonstrate the importance of the hierarchical classification of biomarkers by analyzing studies of clusters
obtained either from digested or undigested tissues and using bottom-up and in-source decay strategies for in-tissue protein
identification. This provides the possibility for the rapid identification of specific markers from different histological
samples and their direct localization in tissues. We present an example from a prostate cancer study using formalin-fixed
paraffin-embedded tissue. 相似文献
110.
Wan S Wu F Rech JC Green ME Balachandran R Horne WS Day BW Floreancig PE 《Journal of the American Chemical Society》2011,133(41):16668-16679
The potent cytotoxins pederin and psymberin have been prepared through concise synthetic routes (10 and 14 steps in the longest linear sequences, respectively) that proceed via a late-stage multicomponent approach to construct the N-acyl aminal linkages. This route allowed for the facile preparation of a number of analogs that were designed to explore the importance of the alkoxy group in the N-acyl aminal and functional groups in the two major subunits on biological activity. These analogs, including a pederin/psymberin chimera, were analyzed for their growth inhibitory effects, revealing several new potent cytotoxins and leading to postulates regarding the molecular conformational and hydrogen bonding patterns that are required for biological activity. Second generation analogs have been prepared based on the results of the initial assays and a structure-based model for the binding of these compounds to the ribosome. The growth inhibitory properties of these compounds are reported. These studies show the profound role that organic chemistry in general and specifically late-stage multicomponent reactions can play in the development of unique and potent effectors for biological responses. 相似文献