12,713 research outputs found
Comparisons of monthly mean cosmic ray counting rates observes from worldwide network of neutron monitors
In order to examine the stability of neutron monitor observation, each of the monthly average counting rates of a neutron monitors is correlated to those of Kiel neutron monitor. The regression coefficients thus obtained are compared with the coupling coefficients of isotropic intensity radiation. The results of the comparisons for five year periods during 1963 to 1982, and for whole period are given. The variation spectrum with a single power law with an exponent of -0.75 up to 50 GV is not so unsatisfactory one. More than one half of the stations show correlations with the coefficient greater than 0.9. Some stations have shifted the level of mean counting rates by changing the instrumental characteristics which can be adjusted
Superconductivity and Abelian Chiral Anomalies
Motivated by the geometric character of spin Hall conductance, the
topological invariants of generic superconductivity are discussed based on the
Bogoliuvov-de Gennes equation on lattices.
They are given by the Chern numbers of degenerate condensate bands for
unitary order, which are realizations of Abelian chiral anomalies for
non-Abelian connections. The three types of Chern numbers for the and
-directions are given by covering degrees of some doubled surfaces around
the Dirac monopoles. For nonunitary states, several topological invariants are
defined by analyzing the so-called -helicity. Topological origins of the
nodal structures of superconducting gaps are also discussed.Comment: An example with a figure and discussions are supplemente
Field-driven topological glass transition in a model flux line lattice
We show that the flux line lattice in a model layered HTSC becomes unstable
above a critical magnetic field with respect to a plastic deformation via
penetration of pairs of point-like disclination defects. The instability is
characterized by the competition between the elastic and the pinning energies
and is essentially assisted by softening of the lattice induced by a
dimensional crossover of the fluctuations as field increases. We confirm
through a computer simulation that this indeed may lead to a phase transition
from crystalline order at low fields to a topologically disordered phase at
higher fields. We propose that this mechanism provides a model of the low
temperature field--driven disordering transition observed in neutron
diffraction experiments on single crystals.Comment: 11 pages, 4 figures available upon request via snail mail from
[email protected]
The prevalence of and factors related to calcium pyrophosphate dihydrate crystal deposition in the knee joint
SummaryObjectivesThe purpose of this study was to reveal the accurate prevalence and related factors to the presence of calcium pyrophosphate dihydrate (CPPD) crystal deposition in cadaveric knee joints.DesignControlled laboratory study.MethodsSix hundred and eight knees from 304 cadavers (332 male knees and 276 female knees, formalin fixed, Japanese anatomical specimens) were included in this study. The average age of the cadavers was 78.3 ± 10.7 years. Knees were macroscopically evaluated for the existence of CPPD, and the depth of cartilage degeneration of the femoro-tibial joint following the Outerbridge's classification. CPPD crystal was confirmed under Fourier transform infrared spectroscopy (FTIR) analysis using light microscopy. Statistical analysis was performed to reveal the correlation between the occurrence of CPPD deposition in the knee joint and gender, age, and the depth of cartilage degeneration of the femoro-tibial joint.ResultsThe prevalence of grossly visible CPPD crystal was 13% (79 knees). In all of these knees, CPPD crystal was confirmed under FTIR analysis. Statistical analysis showed significant correlation between the occurrence of CPPD deposition and gender (P < 0.001), and depth of cartilage degeneration in the femoro-tibial joint (P < 0.001). In the cartilage degeneration positive knees (Over grade 3 in Outerbridge's classification), average age of CPPD deposition knee was significantly higher than CPPD negative knees.ConclusionsIn this study, the prevalence of CPPD deposition disease was evaluated in a relatively large sample size of cadaveric knees. The prevalence of CPPD deposition disease was 13%, and was significantly correlated with the subject's age, gender, and severity of cartilage degeneration in the femoro-tibial joint
Topological Origin of Zero-Energy Edge States in Particle-Hole Symmetric Systems
A criterion to determine the existence of zero-energy edge states is
discussed for a class of particle-hole symmetric Hamiltonians. A ``loop'' in a
parameter space is assigned for each one-dimensional bulk Hamiltonian, and its
topological properties, combined with the chiral symmetry, play an essential
role. It provides a unified framework to discuss zero-energy edge modes for
several systems such as fully gapped superconductors, two-dimensional d-wave
superconductors, and graphite ribbons. A variants of the Peierls instability
caused by the presence of edges is also discussed.Comment: Completely rewritten. Discussions on coexistence of is- or
id_{xy}-wave order parameter near edges in d_{x^{2}-y^{2}}-wave
superconductors are added; 4 pages, 3 figure
Singular Density of States of Disordered Dirac Fermions in the Chiral Models
The Dirac fermion in the random chiral models is studied which includes the
random gauge field model and the random hopping model. We focus on a connection
between continuum and lattice models to give a clear perspective for the random
chiral models. Two distinct structures of density of states (DoS) around zero
energy, one is a power-law dependence on energy in the intermediate energy
range and the other is a diverging one at zero energy, are revealed by an
extensive numerical study for large systems up to . For the
random hopping model, our finding of the diverging DoS within very narrow
energy range reconciles previous inconsistencies between the lattice and the
continuum models.Comment: 4 pages, 4 figure
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