6,898 research outputs found
Intrinsic vs. extrinsic anomalous Hall effect in ferromagnets
A unified theory of the anomalous Hall effect (AHE) is presented for
multi-band ferromagnetic metallic systems with dilute impurities. In the clean
limit, the AHE is mostly due to the extrinsic skew-scattering. When the Fermi
level is located around anti-crossing of band dispersions split by spin-orbit
interaction, the intrinsic AHE to be calculated ab initio is resonantly
enhanced by its non-perturbative nature, revealing the extrinsic-to-intrinsic
crossover which occurs when the relaxation rate is comparable to the spin-orbit
interaction energy.Comment: 5 pages including 4 figures, RevTex; minor changes, to appaer in
Phys. Rev. Let
Complete solution for unambiguous discrimination of three pure states with real inner products
Complete solutions are given in a closed analytic form for unambiguous
discrimination of three general pure states with real mutual inner products.
For this purpose, we first establish some general results on unambiguous
discrimination of n linearly independent pure states. The uniqueness of
solution is proved. The condition under which the problem is reduced to an
(n-1)-state problem is clarified. After giving the solution for three pure
states with real mutual inner products, we examine some difficulties in
extending our method to the case of complex inner products. There is a class of
set of three pure states with complex inner products for which we obtain an
analytical solution.Comment: 13 pages, 3 figures, presentation improved, reference adde
Discrimination with error margin between two states - Case of general occurrence probabilities -
We investigate a state discrimination problem which interpolates
minimum-error and unambiguous discrimination by introducing a margin for the
probability of error. We closely analyze discrimination of two pure states with
general occurrence probabilities. The optimal measurements are classified into
three types. One of the three types of measurement is optimal depending on
parameters (occurrence probabilities and error margin). We determine the three
domains in the parameter space and the optimal discrimination success
probability in each domain in a fully analytic form. It is also shown that when
the states to be discriminated are multipartite, the optimal success
probability can be attained by local operations and classical communication.
For discrimination of two mixed states, an upper bound of the optimal success
probability is obtained.Comment: Final version, 9 pages, references added, presentation improve
A G1-like globular cluster in NGC 1023
The structure of a very bright (MV = -10.9) globular cluster in NGC 1023 is
analyzed on two sets of images taken with the Hubble Space Telescope. From
careful modeling of King profile fits to the cluster image, a core radius of
0.55+/-0.1 pc, effective radius 3.7+/-0.3 pc and a central V-band surface
brightness of 12.9+/-0.5 mag / square arcsec are derived. This makes the
cluster much more compact than Omega Cen, but very similar to the brightest
globular cluster in M31, G1 = Mayall II. The cluster in NGC 1023 appears to be
very highly flattened with an ellipticity of about 0.37, even higher than for
Omega Cen and G1, and similar to the most flattened clusters in the Large
Magellanic Cloud.Comment: 14 pages, 3 figures, 1 table. Accepted for AJ, Oct 200
Astrophysical properties of binary star clusters in the Small Magellanic Cloud
To study the evolution of binary star clusters we have imaged 7 systems in
the Small Magellanic Cloud with SOAR 4-m telescope using B and V filters. The
sample contains pairs with well-separated components (d < 30 pc) as well as
systems that apparently merged, as evidenced by their unusual structures. By
employing isochrone fittings to their CMDs we have determined reddening, age
and metallicity and by fitting King models to their radial stellar density
profile we have estimated core radius. Disturbances of the density profile are
interpreted as an evidence of interaction. Circunstances as distances between
components and their age difference are addressed in terms of the timescales
involved to access the physical connection of the system. In two cases the age
difference is above 50 Myr, which suggests chance alignment, capture or
sequential star formation.Comment: 4 pages, 1 figure. To appear in online version of Proc. IAU Symp. 266
(Star clusters), eds. R. de Grijs and J. Lepin
Field-induced metal-insulator transition and switching phenomenon in correlated insulators
We study the nonequilibrium switching phenomenon associated with the
metal-insulator transition under electric field E in correlated insulator by a
gauge-covariant Keldysh formalism. Due to the feedback effect of the resistive
current I, this occurs as a first-order transition with a hysteresis of I-V
characteristics having a lower threshold electric field (\sim 10^4 Vcm^{-1})
much weaker than that for the Zener breakdown. It is also found that the
localized mid-gap states introduced by impurities and defects act as hot spots
across which the resonant tunneling occurs selectively, which leads to the
conductive filamentary paths and reduces the energy cost of the switching
function.Comment: 5 pages, 3 figures. A study on the metal-insulator transition in
correlated insulators was adde
Response of spinal myoclonus to a combination therapy of autogenic training and biofeedback
<p>Abstract</p> <p>Introduction</p> <p>Clinical evidence indicates that certain types of movement disorders are due to psychosomatic factors. Patients with myoclonic movements are usually treated by a variety of therapeutic agents. Autogenic training (AT), a recognized form of psychosomatic therapies, is suitable for certain types of neurological diseases. We describe a patient with myoclonus who failed to respond to conventional medical therapy. His symptoms were exaggerated by psychogenic factors, especially anger.</p> <p>Case presentation</p> <p>A 42-year-old man was admitted to our hospital, Preventive Welfare Clinic, for severe paroxysmal axial myoclonus of the left shoulder and abdominal muscles. The initial diagnosis was "combination of spinal segmental myoclonus and propriospinal myoclonus". The myoclonic movements did not occur during sleep but were aggravated by bathing, alcohol drinking, and anger. Psychological examination indicated hostile attribution. Although considered not to be a case of psychogenic myoclonus, a "<it>psychogenic factor</it>" was definitely involved in the induction of the organic myoclonus. The final diagnosis was "combination of spinal segmental myoclonus and propriospinal myoclonus accompanied by features of psychosomatic disorders". The patient underwent psychosomatic therapy including AT and surface electromyography (EMG)-biofeedback therapy and treatment with clonazepam and carbamazepine.</p> <p>Results</p> <p>AT and EMG-biofeedback resulted in shortening the duration and reducing the amplitude and frequency of the myoclonic discharges.</p> <p>Conclusion</p> <p>Psychosomatic therapy with AT and surface EMG-biofeedback produced excellent improvement of myoclonic movements and allowed the reduction of the dosage of conventional medications.</p
A double-label study of efferent projections from the Edinger-Westphal nucleus in goldfish and kelp bass
The Edinger-Westphal nucleus in goldfish was identified by retrograde labeling from the ciliary ganglion. In the same animals a few neurons near this nucleus (perinuclear Edinger-Westphal neurons) were labeled by a different retrograde tracer injected into the cerebellum. No double-labeled cells were found. Similar results were obtained in kelp bass, except that in this species no cerebellar-projecting perinuclear neurons were observed. Cerebellar-projecting Edinger-Westphal neurons have previously been described in some mammals, but not in other vertebrates. Therefore the homology of cerebellar-projecting cells of the Edinger-Westphal region in mammals and teleost fishes is doubtful
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