7,055 research outputs found
Study of nickel hydroxide electrodes. 2: Oxidation products of nickel (2) hydroxides
Pure phases of some oxidized Ni oxides were prepared galvanimetrically with the Ni(2) hydroxide electrode of an alkaline battery. The crystallographic data of these phases, their chemical behavior, and conditions of transition were studied
Cost of dynamical quark simulations: O(a) improved Wilson fermions
I report on cost estimates and algorithmic performance in simulations using 2
flavours of non-perturbatively O(a) improved Wilson quarks together with the
Wilson plaquette action.Comment: Contribution to Lattice2001 (panel discussion), 2 pages, 2 figure
The three-loop beta-fuction of QCD with the clover action
We calculate, to 3 loops in perturbation theory, the bare -function of
QCD, formulated on the lattice with the clover fermionic action. The dependence
of our result on the number of colors , the number of fermionic flavors
, as well as the clover parameter , is shown explicitly.
A direct outcome of our calculation is the two-loop relation between the bare
coupling constant and the one renormalized in the MS-bar scheme.
Further, we can immediately derive the three-loop correction to the relation
between the lattice -parameter and , which is important in checks
of asymptotic scaling. For typical values of , this correction is found
to be very pronounced.Comment: 14 pages, 2 eps figure
Swift observations of the 2006 outburst of the recurrent nova RS Ophiuchi: III. X-ray spectral modelling
Following the Swift X-ray observations of the 2006 outburst of the recurrent
nova RS Ophiuchi, we developed hydrodynamical models of mass ejection from
which the forward shock velocities were used to estimate the ejecta mass and
velocity. In order to further constrain our model parameters, here we present
synthetic X-ray spectra from our hydrodynamical calculations which we compare
to the Swift data. An extensive set of simulations was carried out to find a
model which best fits the spectra up to 100 days after outburst. We find a good
fit at high energies but require additional absorption to match the low energy
emission. We estimate the ejecta mass to be in the range (2-5) x 10^{-7} solar
masses and the ejection velocity to be greater than 6000 km/s (and probably
closer to 10,000 km/s). We also find that estimates of shock velocity derived
from gas temperatures via standard model fits to the X-ray spectra are much
lower than the true shock velocities.Comment: 13 pages, 5 figures, Accepted for publication in Ap
Kramers-Kronig, Bode, and the meaning of zero
The implications of causality, as captured by the Kramers-Kronig relations
between the real and imaginary parts of a linear response function, are
familiar parts of the physics curriculum. In 1937, Bode derived a similar
relation between the magnitude (response gain) and phase. Although the
Kramers-Kronig relations are an equality, Bode's relation is effectively an
inequality. This perhaps-surprising difference is explained using elementary
examples and ultimately traces back to delays in the flow of information within
the system formed by the physical object and measurement apparatus.Comment: 8 pages; American Journal of Physics, to appea
Monopole Current Dynamics and Color Confinement
Color confinement can be understood by the dual Higgs theory, where monopole
condensation leads to the exclusion of the electric flux from the QCD vacuum.
We study the role of the monopole for color confinement by investigating the
monopole current system. When the self-energy of the monopole current is small
enough, long and complicated monopole world-lines appear, which is a signal of
monopole condensation. In the dense monopole system, the Wilson loop obeys the
area-law, and the string tension and the monopole density have similar behavior
as the function of the self-energy, which seems that monopole condensation
leads to color confinement. On the long-distance physics, the monopole current
system almost reproduces essential features of confinement properties in
lattice QCD. In the short-distance physics, however, the monopole-current
theory would become nonlocal and complicated due to the monopole size effect.
This monopole size would provide a critical scale of QCD in terms of the dual
Higgs mechanism.Comment: 6 pages LaTeX, 5 figures, uses espcrc1.sty, Talk presented at
International Conference on Quark Lepton Nuclear Physics, Osaka, May. 199
Spin-polarized surface states close to adatoms on Cu(111)
We present a theoretical study of surface states close to 3d transition metal
adatoms (Cr, Mn, Fe, Co, Ni and Cu) on a Cu(111) surface in terms of an
embedding technique using the fully relativistic Korringa-Kohn-Rostoker method.
For each of the adatoms we found resonances in the s-like states to be
attributed to a localization of the surface states in the presence of an
impurity. We studied the change of the s-like densities of states in the
vicinity of the surface state band-edge due to scattering effects mediated via
the adatom's d-orbitals. The obtained results show that a magnetic impurity
causes spin-polarization of the surface states. In particular, the long-range
oscillations of the spin-polarized s-like density of states around an Fe adatom
are demonstrated.Comment: 5 pages, 5 figures, submitted to PR
Determination of the Her-2/neu gene amplification status in cytologic breast cancer specimens using automated silver-enhanced in-situ hybridization (SISH)
Silver-enhanced in-situ hybridization (SISH) is an emerging tool for the determination of the Her-2/neu amplification status in breast cancer. SISH is technically comparable to fluorescence in-situ hybridization (FISH) but does not require a fluorescence microscope for its interpretation. Although recent studies on histologic evaluations of SISH are promising, we aimed to evaluate its performance on 71 cytologic breast cancer specimens with the new combined Her-2/Chr17 probe. Her-2/neu status as routinely determined by FISH was available for all patients. We found SISH signals in cytologic cell blocks and smear specimens easy to evaluate in most cases. Small numbers of tumor cells and difficulties in identifying tumor cells in lymphocyte-rich backgrounds were limiting factors. Her-2/neu status, as determined by Her-2/Chr17 SISH, was basically identical to the results of the corresponding FISH. The discrepancies were mainly owing to the heterogeneity of Her-2/neu amplification in the tumor tissue. Interobserver agreement for the SISH evaluation was high (kappa value: 0.972). We conclude that Her-2/Chr17 SISH is a useful and accurate method for the evaluation of the Her-2/neu gene amplification status in cytologic breast cancer specimens, particularly in metastatic breast cancer lesions. The advantages of signal permanency and bright-field microscopic result interpretation make this technique an attractive alternative to the current FISH-based gold standard
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