470 research outputs found
Non-uniform Matter in Neutron Star Crusts Studied by the Variational Method with Thomas-Fermi Calculations
The equation of state (EOS) for neutron star (NS) crusts is studied in the
Thomas-Fermi (TF) approximation using the EOS for uniform nuclear matter
obtained by the variational method with the realistic nuclear Hamiltonian. The
parameters associated with the nuclear three-body force, which are introduced
to describe the saturation properties, are finely adjusted so that the TF
calculations for isolated atomic nuclei reproduce the experimental data on
masses and charge distributions satisfactorily. The resulting root-mean-square
deviation of the masses from the experimental data for mass-measured nuclei is
about 3 MeV. With use of the nuclear EOS thus determined, the nuclei in the
crust of NS at zero temperature are calculated. The predicted proton numbers of
the nuclei in the crust of NS are close to the gross behavior of the results by
Negele and Vautherin, while they are larger than those for the EOS by Shen et
al. due to the difference in the symmetry energy. The density profile of NS is
calculated with the constructed EOS.Comment: 38 pages, 9 figures, accepted for publication in PT
Variational Calculation for the Equation of State of Nuclear Matter at Finite Temperatures
An equation of state (EOS) for uniform nuclear matter is constructed at zero
and finite temperatures with the variational method starting from the realistic
nuclear Hamiltonian composed of the Argonne V18 and UIX potentials. The energy
is evaluated in the two-body cluster approximation with the three-body-force
contribution treated phenomenologically so as to reproduce the empirical
saturation conditions. The obtained energies for symmetric nuclear matter and
neutron matter at zero temperature are in fair agreement with those by Akmal,
Pandharipande and Ravenhall, and the maximum mass of the neutron star is 2.2
Msolar. At finite temperatures, a variational method by Schmidt and
Pandharipande is employed to evaluate the free energy, which is used to derive
various thermodynamic quantities of nuclear matter necessary for supernova
simulations. The result of this variational method at finite temperatures is
found to be self-consistent.Comment: Revised Versio
Survivin a radiogenetic promoter for glioblastoma viral gene therapy independently from CArG motifs
BACKGROUND: Radiogenetic therapy is a novel approach in the treatment of cancer, which employs genetic modification to alter the sensitivity of tumor cells to the effect of applied radiation. AIM: To select a potent radiation inducible promoter in the context of brain tumors and to investigate if CArG radio responsive motifs or other elements in the promoter nucleotide sequences can correlate to its response to radiation. METHODS: To select initial candidates for promoter inducible elements, the levels of mRNA expression of six different promoters were assessed using Quantitative RTPCR in D54 MG cells before and after radiation exposure. Recombinant Ad/reporter genes driven by five different promoters; CMV, VEGF, FLT-1, DR5 and survivin were constructed. Glioma cell lines were infected with different multiplicity of infection of the (promoter) Ad or CMV Ad. Cells were then exposed to a range of radiation (0â12Â Gy) at single fraction. Fluorescent microscopy, Luc assay and X-gal staining was used to detect the level of expression of related genes. Different glioma cell lines and normal astrocytes were infected with Ad survivin and exposed to radiation. The promoters were analyzed for presence of CArG radio-responsive motifs and CCAAT box consensus using NCBI blast bioinformatics software. RESULTS: Radiotherapy increases the expression of gene expression by 1.25â2.5 fold in different promoters other than survivin after 2Â h of radiation. RNA analysis was done and has shown an increase in copy number of tenfold for survivin. Most importantly cells treated with RT and Ad Luc driven by survivin promoter showed a fivefold increase in expression after 2Â Gy of radiation in comparison to non-irradiated cells. Presence or absence of CArG motifs did not correlate with promoter response to radiation. Survivin with the best response to radiation had the lowest number of CCAAT box. CONCLUSION: Survivin is a selective potent radiation inducible promoter for glioblastoma viral gene therapy and this response to radiation could be independent of CArG motifs
Near-Infrared Adaptive Optics Spectroscopy of Binary Brown Dwarf HD 130948B and C
We present near-infrared spectroscopy of low-mass companions in a nearby
triple system HD 130948 (Gliese 564, HR 5534). Adaptive optics on the Subaru
Telescope allowed spectroscopy of the individual components of the 0".13 binary
system. Based on a direct comparison with a series of template spectra, we
determined the spectral types of HD 130948B and C to be L4 +- 1. If we take the
young age of the primary star into account (0.3-0.8 Gyr), HD 130948B and C most
likely are a binary brown dwarf system.Comment: 6 pages, 3 figures, accepted for publication in ApJ Letter
A Subarcsecond Companion to the T Tauri Star AS 353B
Adaptive optics imaging of the bright visual T Tauri binary AS 353 with the
Subaru Telescope shows that it is a hierarchical triple system. The secondary
component, located 5.6" south of AS 353A, is resolved into a subarcsecond
binary, AS 353Ba and Bb, separated by 0.24". Resolved spectroscopy of the two
close components shows that both have nearly identical spectral types of about
M1.5. Whereas AS 353A and Ba show clear evidence for an infrared excess, AS
353Bb does not. We discuss the possible role of multiplicity in launching the
large Herbig-Haro flow associated with AS 353A.Comment: AASTeXv5.0, 21 pages, 5 figures, Astronomical Journal, in pres
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