595 research outputs found
Temperature dependence of spin resonance in cobalt substituted NiZnCu ferrites
Cobalt substitutions were investigated in Ni0.4Zn0.4Cu0.2Fe2O4 ferrites,
initial complex permeability was then measured from 1 MHz to 1 GHz. It appears
that cobalt substitution led to a decrease in the permeability and an increase
in the \mus\timesfr factor. As well, it gave to the permeability spectrum a
sharp resonance character. We also observed a spin reorientation occurring at a
temperature depending on the cobalt content. Study of the complex permeability
versus temperature highlighted that the most resonant character was obtained at
this temperature. This shows that cobalt contribution to second order
magnetocrystalline anisotropy plays a leading role at this temperature
Clinical features of a novel TIMP-3 mutation causing Sorsby's fundus dystrophy: implications for disease mechanism
AIMS: To describe the phenotype in three family members affected by a novel mutation in the gene coding for the enzyme tissue inhibitor of metalloproteinase-3 (TIMP-3).
METHODS: Three members of the same family were seen with a history of nyctalopia and visual loss due to maculopathy. Clinical features were consistent with Sorsby's fundus dystrophy. Exon 5 of the gene coding for TIMP-3 was amplified by the polymerase chain reaction, single strand conformation polymorphism analysis undertaken and exon 5 amplicons were directly sequenced.
RESULTS: Onset of symptoms was in the third to fourth decade. Five of six eyes had geographic macular atrophy rather than neovascularisation as a cause for central visual loss. Peripheral retinal pigmentary disturbances were present. Scotopic ERGs were abnormal in all three. Mutation analysis showed a GT transversion in all three resulting in a premature termination codon, E139X, deleting most of the carboxy terminal domain of TIMP-3.
CONCLUSIONS: The patients described had a form of Sorsby's fundus dystrophy which fell at the severe end of the spectrum of this disease. Postulated disease mechanisms include deposition of dimerised TIMP-3 protein
Dynamical Four-Form Fields
We present an example of a gauge-invariant Lagrangian that contains four
derivatives and describes one massive, non-ghostlike, degree of freedom.Comment: 5 page
Partition function of dyonic black holes in N=4 string theory
The dominant contribution to the semicanonical partition function of dyonic
black holes of N=4 string theory is computed for generic charges, generalizing
recent results of Shih and Yin. The result is compared to the black hole free
energy obtained from the conjectured relation to topological strings. If
certain perturbative corrections are included agreement is found to subleading
order. These corrections modify the conjectured relation and implement
covariance with respect to electric-magnetic duality transformations.Comment: 9 page
Combined potential and spin impurity scattering in cuprates
We present a theory of combined nonmagnetic and magnetic impurity scattering
in anisotropic superconductors accounting for the momentum-dependent impurity
potential. Applying the model to the d-wave superconducting state, we obtain a
quantitative agreement with the initial suppression of the critical temperature
due to Zn and Ni substitutions as well as electron irradiation defects in the
cuprates. We suggest, that the unequal pair-breaking effect of Zn and Ni may be
related to a different nature of the magnetic moments induced by these
impurities.Comment: 5 pages, 3 tables, RevTex, to be published in Phys. Rev.
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