Showing 1241 - 1250 of 2039 Items
Inclusive decay B→ηX
Date: 1996-01-01
Creator: Y. Kubota
M. Lattery
M. Momayezi
J. K. Nelson
S., Patton
R. Poling
V. Savinov
S. Schrenk
R. Wang
M. S. Alam
I. J. Kim
Z. Ling
A. H. Mahmood
J. J. O’Neill
H. Severini
C. R. Sun
F. Wappler
G. Crawford
C. M. Daubenmier
R. Fulton
D. Fujino
K. K. Gan
K. Honscheid
H. Kagan
R. Kass
J. Lee
M. Sung
C. White
A. Wolf
M. M. Zoeller
F. Butler
Access: Open access
- Using data samples taken at the Υ(4S) resonance and nearby continuum e+e- annihilation with the CLEO-II detector at CESR, we have measured the inclusive branching fraction B(B→ηX)=(17.6±1.1±1.2)%, and the momentum distribution of the η mesons from B meson decay. The η yield cannot be explained as arising solely from the decay of intermediate charmed mesons. © 1996 The American Physical Society.
Measurement of the decay asymmetry parameters in Λc+ → Λπ+ and Λc+ → Σ+π0
Date: 1995-05-11
Creator: M. Bishai
J. Fast
E. Gerndt
J. W. Hinson
R. L., McIlwain
T. Miao
D. H. Miller
M. Modesitt
D. Payne
E. I. Shibata
I. P.J. Shipsey
P. N. Wang
M. Battle
J. Ernst
L. Gibbons
Y. Kwon
S. Roberts
E. H. Thorndike
C. H. Wang
J. Dominick
M. Lambrecht
S. Sanghera
V. Shelkov
T. Skwarnicki
R. Stroynowski
I. Volobouev
G. Wei
M. Artuso
M. Gao
M. Goldberg
D. He
Access: Open access
- We have measured the weak decay asymmetry parameters (αΛc) for two Λc+ decay modes. Our measurements are αΛc = -0.94-0.06-0.06+0.21+0.12 for the decay mode Λc+ → Λπ+ and αΛc = -0.45 ±0.31 ±0.06 for the decay mode Λc → Σ+ π0. By combining these measurements with the previously measured decay rates, we have extracted the parity-violating and parity-conserving amplitudes. These amplitudes are used to test models of nonleptonic charmed baryon decay. © 1995.
Targeted identification of glycosylated proteins in the gastric pathogen helicobacter pylori (Hp)
Date: 2013-09-01
Creator: Kanokwan Champasa
Scott A. Longwell
Aimee M. Eldridge
Elizabeth A. Stemmler
Danielle H., Dube
Access: Open access
- Virulence of the gastric pathogen Helicobacter pylori (Hp) is directly linked to the pathogen's ability to glycosylate proteins; for example, Hp flagellin proteins are heavily glycosylated with the unusual nine-carbon sugar pseudaminic acid, and this modification is absolutely essential for Hp to synthesize functional flagella and colonize the host's stomach. Although Hp's glycans are linked to pathogenesis, Hp's glycome remains poorly understood; only the two flagellin glycoproteins have been firmly characterized in Hp. Evidence from our laboratory suggests that Hp synthesizes a large number of as-yet unidentified glycoproteins. Here we set out to discover Hp's glycoproteins by coupling glycan metabolic labeling with mass spectrometry analysis. An assessment of the subcellular distribution of azide-labeled proteins by Western blot analysis indicated that glycoproteins are present throughout Hp and may therefore serve diverse functions. To identify these species, Hp's azide-labeled glycoproteins were tagged via Staudinger ligation, enriched by tandem affinity chromatography, and analyzed by multidimensional protein identification technology. Direct comparison of enriched azide-labeled glycoproteins with a mock-enriched control by both SDS-PAGE and mass spectrometry-based analyses confirmed the selective enrichment of azide-labeled glycoproteins. We identified 125 candidate glycoproteins with diverse biological functions, including those linked with pathogenesis. Mass spectrometry analyses of enriched azide-labeled glycoproteins before and after cleavage of O-linked glycans revealed the presence of Staudinger ligation-glycan adducts in samples only after beta-elimination, confirming the synthesis of O-linked glycoproteins in Hp. Finally, the secreted colonization factors urease alpha and urease beta were biochemically validated as glycosylated proteins via Western blot analysis as well as by mass spectrometry analysis of cleaved glycan products. These data set the stage for the development of glycosylation-based therapeutic strategies, such as new vaccines based on natively glycosylated Hp proteins, to eradicate Hp infection. Broadly, this report validates metabolic labeling as an effective and efficient approach for the identification of bacterial glycoproteins. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.
Luminosity measurement with the CLEO II detector
Date: 1994-07-01
Creator: G. Crawford
C. M. Daubenmier
R. Fulton
D. Fujino
K. K., Gan
K. Honscheid
H. Kagan
R. Kass
J. Lee
R. Malchow
Y. Skovpen
M. Sung
C. White
F. Butler
X. Fu
G. Kalbfleisch
W. R. Ross
P. Skubic
M. Wood
J. Fast
R. L. McIlwain
T. Miao
D. H. Miller
M. Modesitt
D. Payne
E. I. Shibata
I. P.J. Shipsey
P. N. Wang
M. Battle
J. Ernst
L. Gibbons
Access: Open access
- A measurement of absolute integrated luminosity is presented using the CLEO II detector operating at the CESR e+e- storage ring. Independent analyses of three different final states (e+e-, γγ, and μ+μ-) at √s {reversed tilde equals} 10 GeV normalize to the expected theoretical cross sections and correct for detection efficiencies. The resulting luminosities are measured with systematic errors of ±1.8%, ±1.6%, and ±2.2%, respectively, and are consistent with one another. The combined luminosity has a systematic error of ±1.0%. © 1994.
Study of the decay Λc+→λl+νl
Date: 1994-03-10
Creator: T. Bergfeld
B. I. Eisenstein
G. Gollin
B. Ong
M., Palmer
M. Selen
J. J. Thaler
A. J. Sadoff
R. Ammar
S. Ball
P. Baringer
A. Bean
D. Besson
D. Coppage
N. Copty
R. Davis
N. Hancock
M. Kelly
N. Kwak
H. Lam
Y. Kubota
M. Lattery
J. K. Nelson
D. Patton
D. Perticone
R. Poling
V. Savinov
S. Schrenk
R. Wang
M. S. Alam
I. J. Kim
Access: Open access
- Using the CLEO II detector at CESR we observe 500 Λl+ pairs consistent with the semileptonic decay Λc+ → λ+ν We measure σ(e+e- → Λ+cX) · B(Λ+c → Λl+νl) = 4.77±0.25±0.66 pb. Combining with the charm semileptonic width and the lifetime of the Λc we also obtain B(Λ+c → pK-π+). We find no evidence for Λl+νl final states in which there are additional Λ+c decay products. We measure the decay asymmetry parameter of Λ+c → Λe+νe to be αΛc = -0.89+0.17+0.09-0.11-0.05. © 1994.
Matrix-model description of N = 2 gauge theories with non-hyperelliptic Seiberg-Witten curves
Date: 2003-12-08
Creator: Stephen G. Naculich
Howard J. Schnitzer
Niclas Wyllard
Access: Open access
- Using matrix-model methods we study three different N=2 models: U(N)×U(N) with matter in the bifundamental representation, U(N) with matter in the symmetric representation, and U(N) with matter in the antisymmetric representation. We find that the (singular) cubic Seiberg-Witten curves (and associated Seiberg-Witten differentials) implied by the matrix models, although of a different form from the ones previously proposed using M-theory, can be transformed into the latter and are thus physically equivalent. We also calculate the one-instanton corrections to the gauge-coupling matrix using the perturbative expansion of the matrix model. For the U(N) theories with symmetric or antisymmetric matter we use the modified matrix-model prescription for the gauge-coupling matrix discussed in our paper: Cubic curves from matrix models and generalized Konishi anomalies (hep-th/0303268). Moreover, in the matrix model for the U(N) theory with antisymmetric matter, one is required to expand around a different vacuum than one would naively have anticipated. With these modifications of the matrix-model prescription, the results of this paper are in complete agreement with those of Seiberg-Witten theory obtained using M-theory methods. © 2003 Elsevier B.V. All rights reserved.
Tame combing and almost convexity conditions
Date: 2011-12-01
Creator: Sean Cleary
Susan Hermiller
Melanie Stein
Jennifer Taback
Access: Open access
- We give the first examples of groups which admit a tame combing with linear radial tameness function with respect to any choice of finite presentation, but which are not minimally almost convex on a standard generating set. Namely, we explicitly construct such combings for Thompson's group F and the Baumslag-Solitar groups BS(1, p) with p ≥ 3. In order to make this construction for Thompson's group F, we significantly expand the understanding of the Cayley complex of this group with respect to the standard finite presentation. In particular we describe a quasigeodesic set of normal forms and combinatorially classify the arrangements of 2-cells adjacent to edges that do not lie on normal form paths. © 2010 Springer-Verlag.
An improved comparison of atmospheric Ar/N2 time series and paired ocean-atmosphere model predictions
Date: 2008-11-16
Creator: Nicolas Cassar
Galen A. McKinley
Michael L. Bender
Robert Mika
Mark, Battle
Access: Open access
- Ar/N2 variations in the atmosphere reflect ocean heat fluxes, air-sea gas exchange, and atmospheric dynamics. Here atmospheric Ar/N2 time series are compared to paired ocean-atmosphere model predictions. Agreement between Ar/N2 observations and simulations has improved in comparison to a previous study because of longer time series and the introduction of automated samplers at several of the atmospheric stations, as well as the refinement of the paired ocean-atmosphere models by inclusion of Ar and N2 as active tracers in the ocean component. Although analytical uncertainties and collection artifacts are likely to be mainly responsible for observed Ar/N2 outliers, air parcel back-trajectory analysis suggests that some of the variability in Ar/N2 measurements could be due to the low-altitude history of the air mass collected and, by extension, the local oceanic Ar/N2 signal. Although the simulated climatological seasonal cycle can currently be evaluated with Ar/N2 observations, longer time series and additional improvements in the signal-to-noise ratio will be required to test other model predictions such as interannual variability, latitudinal gradients, and the secular increase in atmospheric Ar/N2 expected to result from ocean warming. Copyright 2008 by the American Geophysical Union.
A cascading N = 1 Sp(2N + 2M) × Sp(2N) gauge theory
Date: 2002-08-26
Creator: Stephen G. Naculich
Howard J. Schnitzer
Niclas Wyllard
Access: Open access
- We study the N=1 Sp(2N + 2M) × Sp(2N) cascading gauge theory on a stack of N physical and M fractional (half) D3-branes at the singularity of an orientifolded conifold. In addition to the D3-branes and an O7-plane, the background contains eight D7-branes, which give rise to matter in the fundamental representation of the gauge group. The moduli space of the gauge theory is analyzed and its structure is related to the brane configurations in the dual type IIB theory and in type IIA/M-theory. © 2002 Elsevier Science B.V. All rights reserved.
Mutations in a signal sequence for the thylakoid membrane identify multiple protein transport pathways and nuclear suppressors
Date: 1994-07-01
Creator: Tracy A. Smith
Bruce D. Kohorn
Access: Open access
- The apparatus that permits protein translocation across the internal thylakoid membranes of chloroplasts is completely unknown, even though these membranes have been the subject of extensive biochemical analysis. We have used a genetic approach to characterize the translocation of Chlamydomonas cytochrome f, a chloroplast-encoded protein that spans the thylakoid once. Mutations in the hydrophobic core of the cytochrome f signal sequence inhibit the accumulation of cytochrome f, lead to an accumulation of precursor, and impair the ability of Chlamydomonas cells to grow photosynthetically. One hydrophobic core mutant also reduces the accumulation of other thylakoid membrane proteins, but not those that translocate completely across the membrane. These results suggest that the signal sequence of cytochrome f is required and is involved in one of multiple insertion pathways. Suppressors of two signal peptide mutations describe at least two nuclear genes whose products likely describe the translocation apparatus, and selected second- site chloroplast suppressors further define regions of the cytochrome f signal peptide.