1,921 research outputs found
Evaluation of Half-metallic Antiferromagnetism in CrFeO ({}=La, Sr
The nearly well-ordered double perovskite LaCrFeO has been
synthesized recently. Contrary to previous theoretical predictions, but in
agreement with experimental observations, our first principle calculations
indicate an insulating ferrimagnet LaCrFeO with antialigned S=3/2
Cr and S=5/2 Fe ions,using the local spin density approximation
(LSDA), a correlated band theory LDA+U, and a semilocal functional modified
Becke-Johnson method. Additionally, we investigated the double perovskite
SrCrFeO, which is as yet unsynthesized. In LSDA calculations, this
system shows formally tetravalent Cr and Fe ions both having antialigned =1
moments, but is a simple metal. Once applying on-site Coulomb repulsion U on
both Cr and Fe ions, this system becomes half-metallic and the moment of Fe is
substantially reduced, resulting in zero net moment. These results are
consistent with our fixed spin moment studies. Our results suggest a precisely
compensated half-metallic SrCrFeO.Comment: 7 page
Prevalence and spatial concordance of visual field deterioration in fellow eyes of glaucoma patients.
PurposeTo examine the prevalence of visual field deterioration in contralateral eyes of patients with worsening open-angle glaucoma and to evaluate the spatial concordance of visual field deterioration between both eyes.MethodsOne hundred sixteen open-angle glaucoma patients who underwent 8 or more visual field examinations over ≥ 6 years of follow-up were included. The rates of the fast and slow components of visual field decay for each of 52 visual field test locations were calculated with point-wise exponential regression analysis. The spatial concordance of visual field deterioration in contralateral eyes was evaluated with a concordance ratio (calculated as the number of overlapping locations divided by the total number of deteriorating locations) and by comparing the rate of decay in corresponding modified glaucoma hemifield test clusters.ResultsThe average visual field mean deviation (± standard deviation [SD]) was -8.5 (± 6.4) dB and the mean (± SD) follow-up time was 9.0 (± 1.6) years. Sixty-three patients had mild damage, 23 had moderate damage, and 30 had severe damage. The mean concordance ratio (± SD) was 0.46 (± 0.32) for the mild group, 0.33 (± 0.27) for the moderate group, and 0.35 (± 0.21) for the severe group. Thirty-one patients (27%) had deterioration in concordant locations (p < 0.05). Visual field deterioration was greater in the superior hemifield than the inferior hemifield (p < 0.05) when evaluated with both the concordance ratio and modified glaucoma hemifield test cluster analysis methods.ConclusionsThere is only fair spatial concordance with regard to visual field deterioration between the both eyes of an individual. We conclude that testing algorithms taking advantage of inter-eye spatial concordance would not be particularly advantageous in the early detection of glaucomatous deterioration
Electron and phonon band-structure calculations for the antipolar SrPtP antiperovskite superconductor: Evidence of low-energy two-dimensional phonons
SrPt3P has recently been reported to exhibit superconductivity with Tc = 8.4
K. To explore its superconducting mechanism, we have performed electron and
phonon band calculations based on the density functional theory, and found that
the superconductivity in SrPt3P is well described by the strong coupling
phonon-mediated mechanism. We have demonstrated that superconducting charge
carriers come from pd\pi-hybridized bands between Pt and P ions, which couple
to low energy (~ 5 meV) phonon modes confined on the ab in-plane. These
in-plane phonon modes, which do not break antipolar nature of SrPt3P, enhance
both the electron-phonon coupling constant \lambda and the critical temperature
Tc. There is no hint of a specific phonon softening feature in the phonon
dispersion, and the effect of the spin-orbit coupling on the superconductivity
is found to be negligible.Comment: 5 pages, 5 figures, 1 tabl
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