398 research outputs found
Treatment outcomes of real-time intraoral sonography-guided implantation technique of 198Au grain brachytherapy for T1 and T2 tongue cancer
It is often challenging to determine the accurate size and shape of oral lesions through computed tomography (CT) or magnetic resonance imaging (MRI) when they are very small or obscured by metallic artifacts, such as dental prostheses. Intraoral ultrasonography (IUS) has been shown to be beneficial in obtaining precise information about total tumor extension, as well as the exact location and guiding the insertion of catheters during interstitial brachytherapy. We evaluated the role of IUS in assessing the clinical outcomes of interstitial brachytherapy with 198Au grains in tongue cancer through a retrospective medical chart review. The data from 45 patients with T1 (n = 21) and T2 (n = 24) tongue cancer, who were mainly treated with 198Au grain implants between January 2005 and April 2019, were included in this study. 198Au grain implantations were carried out, and positioning of the implants was confirmed by IUS, to ensure that 198Au grains were appropriately placed for the deep border of the tongue lesion. The five-year local control rates of T1 and T2 tongue cancers were 95.2% and 95.5%, respectively. We propose that the use of IUS to identify the extent of lesions and the position of implanted grains is effective when performing brachytherapy with 198Au grains
Effects of Orbital Degeneracy and Electron Correlation on Charge Dynamics in Perovskite Manganese Oxides
Taking the orbital degeneracy of conduction bands and the Coulomb
interaction into account in a double-exchange model, we investigate charge
dynamics of perovskite Mn oxides by the Lanczs diagonalization
method. In the metallic phase near the Mott insulator, it is found that the
optical conductivity for a spin-polarized two-dimensional system exhibits a
weight transfer to a broad and incoherent structure within the lower-Hubbard
band together with a suppressed Drude weight. It reproduces qualitative feature
of the experimental results. As an orbital effect, we find that an anomalous
charge correlation at quarter filling suppresses the coherent charge dynamics
and signals precursor to the charge ordering.Comment: 4 pages LaTeX including 3 PS figures, to appear in J. Phys. Soc. Jp
Theory of spin wave excitations of metallic A-type antiferromagnetic manganites
The spin dynamic of the metallic A-type antiferromagnetic manganites is
studied. An effective nearest-neighbour Heisenberg spin wave dispersion is
derived from the double exchange model taking into account the superexchange
interaction between the core spins. The result of inelastic neutron scattering
experiment on is qualitatively reproduced.
Comparing theory with experimental data two main parameters of the model:
nearest-neighbour electron transfer amplitude and superexchange coupling
between the core spins are estimated.Comment: to appear in Phys. Rev.
Magnetic Reconnection in Non-Equilibrium Ionization Plasma
We have studied the effect of time-dependent ionization and recombination
processes on magnetic reconnection in the solar corona. Petschek-type steady
reconnection, in which model the magnetic energy is mainly converted at the
slow-mode shocks, was assumed. We carried out the time-dependent ionization
calculation in the magnetic reconnection structure. We only calculated the
transient ionization of iron; the other species were assumed to be in
ionization equilibrium. The intensity of line emissions at specific wavelengths
were also calculated for comparison with {\it Hinode} or other observations in
future. What we found is as follows: (1) iron is mostly in non-equilibrium
ionization in the reconnection region, (2) the intensity of line emission
estimated by the time-dependent ionization calculation is significantly
different from that with the ionization equilibrium assumption, (3) the effect
of time-dependent ionization is sensitive to the electron density in the case
that the electron density is less than cm, (4) the effect of
thermal conduction lessens the time-dependent ionization effect, (5) the effect
of radiative cooling is negligibly small even if we take into account
time-dependent ionization.Comment: accepted for publication in The Astrophysical Journa
Researches in Japan on heavy ion inertial fusion
Recent research activities in Japan are presented
in this paper in heavy ion inertial fusion (HIF) [1]:
shown are particle accelerator developments, beam
dynamics researches, interaction between heavy
ions and target materials, ion source developments,
and illumination schemes of heavy ion beams
(HIBs) in HIF..
Extension and its characteristics of ECRH plasma in the LHD
One of the main objectives of the LHD is to extend the plasma confinement
database for helical systems and to demonstrate such extended plasma
confinement properties to be sustained in steady state. Among the various
plasma parameter regimes, the study of confinement properties in the
collisionless regime is of particular importance. Electron cyclotron resonance
heating (ECRH) has been extensively used for these confinement studies of the
LHD plasma from the initial operation. The system optimizations including the
modification of the transmission and antenna system are performed with the
special emphasis on the local heating properties. As the result, central
electron temperature of more than 10 keV with the electron density of 0.6 x
10 m is achieved near the magnetic axis. The electron temperature
profile is characterized by a steep gradient similar to those of an internal
transport barrier observed in tokamaks and stellarators. 168 GHz ECRH system
demonstrated efficient heating at over the density more than 1.0 x 10
m. CW ECRH system is successfully operated to sustain 756 s discharge.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004,
Nice (France
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