5,398 research outputs found
Protective Role of CYP1A1*2A in the Development of Multiple Myeloma
Introduction and Aims: We had previously reported the association of the N QO1*2/*2 polymorphism with a decreased risk for multiple myeloma (MM) in Koreans (odds ratio [OR], 0.24; 95% CI, 0.01-0.68).
Proton and Helium Spectra from the CREAM-III Flight
Primary cosmic-ray elemental spectra have been measured with the
balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The
third CREAM payload (CREAM-III) flew for 29 days during the 2007-2008 Antarctic
season. Energies of incident particles above 1 TeV are measured with a
calorimeter. Individual elements are clearly separated with a charge resolution
of ~0.12 e (in charge units) and ~0.14 e for protons and helium nuclei,
respectively, using two layers of silicon charge detectors. The measured proton
and helium energy spectra at the top of the atmosphere are harder than other
existing measurements at a few tens of GeV. The relative abundance of protons
to helium nuclei is 9.53+-0.03 for the range of 1 TeV/n to 63 TeV/n. The ratio
is considerably smaller than other measurements at a few tens of GeV/n. The
spectra become softer above ~20 TeV. However, our statistical uncertainties are
large at these energies and more data are needed
Cosmic-Ray Proton and Helium Spectra from the First CREAM Flight
Cosmic-ray proton and helium spectra have been measured with the
balloon-borne Cosmic Ray Energetics And Mass experiment flown for 42 days in
Antarctica in the 2004-2005 austral summer season. High-energy cosmic-ray data
were collected at an average altitude of ~38.5 km with an average atmospheric
overburden of ~3.9 g cm. Individual elements are clearly separated with
a charge resolution of ~0.15 e (in charge units) and ~0.2 e for protons and
helium nuclei, respectively. The measured spectra at the top of the atmosphere
are represented by power laws with a spectral index of -2.66 0.02 for
protons from 2.5 TeV to 250 TeV and -2.58 0.02 for helium nuclei from 630
GeV/nucleon to 63 TeV/nucleon. They are harder than previous measurements at a
few tens of GeV/nucleon. The helium flux is higher than that expected from the
extrapolation of the power law fitted to the lower-energy data. The relative
abundance of protons to helium nuclei is 9.1 0.5 for the range from 2.5
TeV/nucleon to 63 TeV/nucleon. This ratio is considerably smaller than the
previous measurements at a few tens of GeV/nucleon.Comment: 20 pages, 4 figure
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