The density of states and conductivity are calculated for scatterers with nonzero range in monolayer graphene within a self-consistent Born approximation. For scatterers with a Gaussian potential, the minimum conductivity at the Dirac point remains universal in the clean limit, but increases with disorder and becomes nonuniversal for long-range scatterers. For charged impurities, we use the Thomas-Fermi approximation for the screening effect. The conductivity increases in proportion to the electron concentration in agreement with experiments and the minimum conductivity becomes about twice as large as the universal value.
Background: In clinical settings, information on morphology of mitral valve leaflet after mitral valve reconstruction is limited. Methods: Between January 1996 and June 2000, 36 underwent mitral valve repair for mitral regurgitation (MR). The etiology of mitral insufficiency was prolapse, dilated annulus, and ischemic. Ring annuloplasty was performed in all cases. Mitral valve short-axis dimension (MVd), vertical distance between annular line and closing point (Vd), coaptation length (CL), coaptation length index (CL/MVd) were measured by the two-dimensional transesophageal echocardiography for the present 11 cases. Results: In 11 cases, residual MR, using a scale from 0 to 4, was 0 in 5 patients, 1 in 4 patients, 2 in 2 patients whose etiology of regurgitation was cardiomyopathy. MVd and Vd decreased significantly (38.7 ± 6.2 to 27.0 ± 5.6 mm, 10.1 ± 7.7 to 6.5 ± 4.6 mm, respectively). CL and CLI increased significantly (6.4 ± 2.4 to 11.6 ± 4.6 mm, 0.16 ± 0.06 to 0.44 ± 0.21, respectively). Among those index, only CLI have a statistically significant negative correlation with the degree of residual MR. Conclusion: The mitral valve ring annuloplasty produce the morphologic change of mitral apparatus, especially the increase of CLI, which may be one of the main factors in regulation of regurgitation
The diamagnetic susceptibility of disordered monolayer graphene containing scatterers with long-range potential is calculated in a self-consistent Born approximation. Explicit numerical results are obtained for a Gaussian potential. The results show that the delta-function susceptibility in the ideal graphene is broadened by disorder and that the broadening is determined by the condition that states can be mixed with those at the Dirac point. For charged impurities, the susceptibility exhibits a double-peak structure as a function of the Fermi energy at zero temperature, due to the rapid decrease in effective scattering strength with the increase of the Fermi level.
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