130 research outputs found
Little String Theory from Double-Scaling Limits of Field Theories
We show that little string theory on S^5 can be obtained as double-scaling
limits of the maximally supersymmetric Yang-Mills theories on RxS^2 and
RxS^3/Z_k. By matching the gauge theory parameters with those in the gravity
duals found by Lin and Maldacena, we determine the limits in the gauge theories
that correspond to decoupling of NS5-brane degrees of freedom. We find that for
the theory on RxS^2, the 't Hooft coupling must be scaled like ln^3(N), and on
RxS^3/Z_k, like ln^2(N). Accordingly, taking these limits in these field
theories gives Lagrangian definitions of little string theory on S^5.Comment: 16 pages, 5 figures. Minor change
Measurement of the Proton and Deuteron Spin Structure Functions g2 and Asymmetry A2
We have measured the spin structure functions g2p and g2d and the virtual
photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 1.0
< Q^2 < 30(GeV/c)^2 by scattering 38.8 GeV longitudinally polarized electrons
from transversely polarized NH3 and 6LiD targets.The absolute value of A2 is
significantly smaller than the sqrt{R} positivity limit over the measured
range, while g2 is consistent with the twist-2 Wandzura-Wilczek calculation. We
obtain results for the twist-3 reduced matrix elements d2p, d2d and d2n. The
Burkhardt-Cottingham sum rule integral - int(g2(x)dx) is reported for the range
0.02 < x < 0.8.Comment: 12 pages, 4 figures, 1 tabl
Measurements of the -Dependence of the Proton and Neutron Spin Structure Functions g1p and g1n
The structure functions g1p and g1n have been measured over the range 0.014 <
x < 0.9 and 1 < Q2 < 40 GeV2 using deep-inelastic scattering of 48 GeV
longitudinally polarized electrons from polarized protons and deuterons. We
find that the Q2 dependence of g1p (g1n) at fixed x is very similar to that of
the spin-averaged structure function F1p (F1n). From a NLO QCD fit to all
available data we find at
Q2=5 GeV2, in agreement with the Bjorken sum rule prediction of 0.182 \pm
0.005.Comment: 17 pages, 3 figures. Submitted to Physics Letters
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A comparison of five surface mixed layer models with a year of observations in the North Atlantic
Five upper ocean mixed layer models driven by ERA-Interim surface forcing are compared with a year of hydrographic observations of the upper 1000âŻm, taken at the Porcupine Abyssal Plain observatory site using profiling gliders. All the models reproduce sea surface temperature (SST) fairly well, with annual mean warm biases of 0.11âŻ
°
C (PWP model), 0.24âŻ
°
C (GLS), 0.31âŻ
°
C (TKE), 0.91âŻ
°
C (KPP) and 0.36âŻ
°
C (OSMOSIS). The main exception is that the KPP model has summer SSTs which are higher than the observations by nearly 3
°
. Mixed layer salinity (MLS) is not reproduced well by the models and the biases are large enough to produce a non-trivial density bias in the Eastern North Atlantic Central Water which forms in this region in winter.
All the models develop mixed layers which are too deep in winter, with average winter mixed layer depth (MLD) biases between 160 and 228âŻm. The high variability in winter MLD is reproduced more successfully by model estimates of the depth of active mixing and/or boundary layer depth than by model MLD based on water column properties. After the spring restratification event, biases in MLD are small and do not appear to be related to the preceding winter biases.
There is a very clear relationship between MLD and local wind stress in all models and in the observations during spring and summer, with increased wind speeds leading to deepening mixed layers, but this relationship is not present during autumn and winter. We hypothesize that the deepening of the MLD in autumn is so strongly driven by the annual cycle in surface heat flux that the winds are less significant in the autumn. The surface heat flux drives a diurnal cycle in MLD and SST from March onwards, though this effect is much more significant in the models than in the observations.
We are unable to identify one model as definitely better than the others. The only clear differences between the models are KPPâs inability to accurately reproduce summer SSTs, and the OSMOSIS modelâs more accurate reproduction of MLS
Inclusive hadron photoproduction from longitudinally polarized protons and deuterons.
We report measurements of the asymmetry A_parallel for inclusive hadron production on longitudinally polarized proton and deuteron targets by circularly polarized photons. The photons were produced via internal and external bremsstrahlung from an electron beam of 48.35 GeV. Asymmetries for both positive and negative signed hadrons, and a subset of identified pions, were measured in the momentum range 1
Measurements of the dependence of the proton and neutron spin structure functions and
he structure functions g1p and g1n have been measured over the range 0.014 < x < 0.9 and 1 < Q2 < 40 GeV2 using deep-inelastic scattering of 48 GeV longitudinally polarized electrons from polarized protons and deuterons. We find that the Q2 dependence of g1p (g1n) at fixed x is very similar to that of the spin-averaged structure function F1p (F1n). From a NLO QCD fit to all available data we find at Q2=5 GeV2, in agreement with the Bjorken sum rule prediction of 0.182 \pm 0.005
Measurement of the deuteron spin structure function for .
New measurements are reported on the deuteron spin structure function g_1^d. These results were obtained from deep inelastic scattering of 48.3 GeV electrons on polarized deuterons in the kinematic range 0.01 < x < 0.9 and 1 < Q^2 < 40 (GeV/c)^2. These are the first high dose electron scattering data obtained using lithium deuteride (6Li2H) as the target material. Extrapolations of the data were performed to obtain moments of g_1^d, including Gamma_1^d, and the net quark polarization Delta Sigma
Cell-Adhesive Responses to Tenascin-C Splice Variants Involve Formation of Fascin Microspikes
Ebola virus epidemiology, transmission, and evolution during seven months in Sierra Leone
The 2013-2015 Ebola virus disease (EVD) epidemic is caused by the Makona variant of Ebola virus (EBOV). Early in the epidemic, genome sequencing provided insights into virus evolution and transmission and offered important information for outbreak response. Here, we analyze sequences from 232 patients sampled over 7 months in Sierra Leone, along with 86 previously released genomes from earlier in the epidemic. We confirm sustained human-to-human transmission within Sierra Leone and find no evidence for import or export of EBOV across national borders after its initial introduction. Using high-depth replicate sequencing, we observe both host-to-host transmission and recurrent emergence of intrahost genetic variants. We trace the increasing impact of purifying selection in suppressing the accumulation of nonsynonymous mutations over time. Finally, we note changes in the mucin-like domain of EBOV glycoprotein that merit further investigation. These findings clarify the movement of EBOV within the region and describe viral evolution during prolonged human-to-human transmission
Next-to-Leading Order QCD Analysis of Polarized Deep Inelastic Scattering Data
We present a Next-to-Leading order perturbative QCD analysis of world data on
the spin dependent structure functions , and , including
the new experimental information on the dependence of . Careful
attention is paid to the experimental and theoretical uncertainties. The data
constrain the first moments of the polarized valence quark distributions, but
only qualitatively constrain the polarized sea quark and gluon distributions.
The NLO results are used to determine the dependence of the ratio
and evolve the experimental data to a constant . We
determine the first moments of the polarized structure functions of the proton
and neutron and find agreement with the Bjorken sum rule.Comment: 21 pages, 4 figures; final version to be published in Phys. Lett. B.
References updated. Uses elsart.cls version 1996/04/22, 2e-1.4
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