9,945 research outputs found
Transmission resonance in a composite plasmonic structure
The design, fabrication, and optical properties of a composite plasmonic
structure, a two-dimentional array of split-ring resonators inserted into
periodic square holes of a metal film, have been reported. A new type of
transmission resonance, which makes a significant difference from the
conventional peaks, has been suggested both theoretically and experimentally.
To understand this effect, a mechanism of ring- resonance induced dipole
emission is proposed.Comment: 14 pages, 4 figure
Herpes simplex keratitis: Challenges in diagnosis and clinical management
Herpes simplex virus is responsible for numerous ocular diseases, the most common of which is herpetic stromal keratitis. This is a recurrent infection of the cornea that typically begins with a subclinical infection of the cornea that establishes a latent infection of sensory ganglia, most often the trigeminal ganglia. Recurring infections occur when the virus is reactivated from latency and travels back to the cornea, where it restimulates an inflammatory response. This inflammatory response can lead to decreased corneal sensation, scarring, and blindness. The diagnosis of these lesions as the result of a recurrent herpes simplex virus infection can at times be problematic. Currently, herpetic stromal keratitis is diagnosed by its clinical presentation on the slit-lamp examination, but the literature does not always support the accuracy of these clinical findings. Other diagnostic tests such as polymerase chain reaction assay, enzyme-linked immunosorbent assay, immunofluorescent antibody, and viral cultures have provided more definitive diagnosis, but also have some limitations. That said, accurate diagnosis is necessary for proper treatment, in order to prevent serious consequences. Current treatment reduces the severity of lesions and controls further viral spread, but does not provide a cure
Theoretical study of phonon-mediated superconductivity beyond Migdal-Eliashberg approximation and Coulomb pseudopotential
In previous theoretical studies of phonon-mediated superconductors, the
electron-phonon coupling is treated by solving the Migdal-Eliashberg equations
under the bare vertex approximation, whereas the effect of Coulomb repulsion is
incorporated by introducing one single pseudopotential parameter. These two
approximations become unreliable in low carrier-density superconductors in
which the vertex corrections are not small and the Coulomb interaction is
poorly screened. Here, we shall go beyond these two approximations and employ
the Dyson-Schwinger equation approach to handle the interplay of
electron-phonon interaction and Coulomb interaction in a self-consistent way.
We first derive the exact Dyson-Schwinger integral equation of the full
electron propagator. Such an equation contains several unknown single-particle
propagators and fermion-boson vertex functions, and thus seems to be
intractable. To solve this difficulty, we further derive a number of identities
satisfied by all the relevant propagators and vertex functions and then use
these identities to show that the exact Dyson-Schwinger equation of electron
propagator is actually self-closed. This self-closed equation takes into
account not only all the vertex corrections, but also the mutual influence
between electron-phonon interaction and Coulomb interaction. Solving it by
using proper numerical methods leads to the superconducting temperature
and other quantities. As an application of the approach, we compute the
of the interfacial superconductivity realized in the one-unit-cell
FeSe/SrTiO system. We find that can be strongly influenced by the
vertex corrections and the competition between phonon-mediated attraction and
Coulomb repulsion.Comment: 13 + 9 pages, 1 figur
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