2,223 research outputs found
Global NLO Analysis of Nuclear Parton Distribution Functions
Nuclear parton distribution functions (NPDFs) are determined by a global
analysis of experimental measurements on structure-function ratios
F_2^A/F_2^{A'} and Drell-Yan cross section ratios
\sigma_{DY}^A/\sigma_{DY}^{A'}, and their uncertainties are estimated by the
Hessian method. The NPDFs are obtained in both leading order (LO) and
next-to-leading order (NLO) of \alpha_s. As a result, valence-quark
distributions are relatively well determined, whereas antiquark distributions
at x>0.2 and gluon distributions in the whole x region have large
uncertainties. The NLO uncertainties are slightly smaller than the LO ones;
however, such a NLO improvement is not as significant as the nucleonic case.Comment: 3 pages, LaTeX, 4 eps files, to be published in the AIP proceedings
of the 9th International Workshop on Neutrino Factories, Superbeams and
Betabeams (NuFact07), Okayama, Japan, August 6 - 11, 2007. A code for
calculating our nuclear parton distribution functions and their uncertainties
can be obtained from http://research.kek.jp/people/kumanos/nuclp.htm
The structure of the shower disk observed at Mt. Norikura
The structure of the EAS shower disk, the arrival time distribution of charged particles at the core of the small or middle size shower, is measured at Mt. Norikura in Japan. Four fast scintillation counters with an area of 0.25 sq m and a fast trigger system are added to the Mt. Norikura EAS array for the study
Fast scintillation counter system and performance
An experimental study of the fast scintillation counter (FS) system to observe a shower disk structure at Mt. Norikura is described, especially the system performance and a pulse wave-form by a single charge particles. The photomultiplier tube (PT) pulse appears at the leading edge of the main pulse. To remove this PT-pulse from the main pulse, the frame of the scintillator vessel was changed. The fast triggering system was made to decrease the dead time which came from the use of the function of the self triggering of the storage oscilloscope (OSC). To provide a new field on the multi-parameter study of the cosmic ray showers, the system response of the FS system also improved as a result of many considerations
Toward Open-Closed String Theoretical Description of Rolling Tachyon
We consider how the time-dependent decay process of an unstable D-brane
should be described in the full (quantum) open-closed string theory. It is
argued that the system, starting from the unstable D-brane configuration, will
evolve in time into the time-independent open string tachyon vacuum
configuration which we assume to be finite, with the total energy conserved. As
a concrete realization of this idea, we construct a toy model describing the
open and closed string tachyons which admits such a time-dependent solution.
The structure of our model has some resemblance to that of open-closed string
field theory.Comment: 1+10 pages, 6 figures. v2: a reference adde
Tachyon Vacuum in Cubic Superstring Field Theory
In this paper we give an exact analytic solution for tachyon condensation in
the modified (picture 0) cubic superstring field theory. We prove the absence
of cohomology and, crucially, reproduce the correct value for the D-brane
tension. The solution is surprising for two reasons: First, the existence of a
tachyon vacuum in this theory has not been definitively established in the
level expansion. Second, the solution {\it vanishes} in the GSO sector,
implying a ``tachyon vacuum'' solution exists even for a {\it BPS} D-brane.Comment: 16 pages, 2 figure
EXPERIMENTAL-STUDY ABOUT THE INFLUENCE OF LIVER DYSFUNCTION UPON CYCLOSPORINE PHARMACOKINETICS
Concentration of vascular endothelial growth factor in the tumour tissue as a prognostic factor of soft tissue sarcomas
Previous studies have shown that the prognosis of patients who have tumours with high microvessel density (MVD) is worse than that of patients who have a lower density in a variety of cancers. In this study, we investigated the clinical relevance of neovascularity assessed by MVD and the concentration of vascular endothelial growth factor (VEGF) in the tumour tissue of patients with soft tissue sarcoma in comparison with major clinicohistologic parameters by univariate and multivariate analysis. In 115 patients with soft tissue sarcoma, MVD was measured by counting vessels stained with factor VIII antibody. The concentration of VEGF in the tumour tissue was determined by enzyme-linked immunosorbent assay. These parameters were then compared with disease outcome. The concentration of VEGF in the tumour tissue, but not MVD, was found to be correlated with disease outcome in patients with soft tissue, sarcoma. VEGF concentration in the tumour tissue showed a relationship with the clinical stage and histologic grade of the tumour. There was no significant difference in the levels of tissue VEGF concentration and MVD among soft tissue sarcomas classified according to histologic type. The level of tissue VEGF concentration in patients who had subsequent local recurrence and metastasis were significantly higher than the respective values in patients who did not have such disease outcome. No significant correlation existed between MVD and the concentration of VEGF in the tumour tissue. Univariate analysis showed that a high tissue VEGF concentration was associated with poor overall survival of the patient and a greater probability that local recurrence and metastasis had occurred. Multivariate analysis revealed that the tissue concentration of VEGF is an independent prognostic factor for the disease outcome of patients with soft tissue sarcoma. VEGF concentration in the tumour tissue, but not MVD, is an additional prognostic parameter for disease outcome in patients with soft tissue sarcoma, regardless of histologic type. © 2001 Cancer Research Campaign http://www.bjcancer.co
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