12,223 research outputs found
Plasmonic Metamaterials: Physical Background and Some Technological Applications
New technological frontiers appear every year, and few are as intriguing as the field of plasmonic metamaterials (PMMs). These uniquely designed materials use coherent electron oscillations to accomplish an astonishing array of tasks, and they present diverse opportunities in many scientific fields.
This paper consists of an explanation of the scientific background of PMMs and some technological applications of these fascinating materials. The physics section addresses the foundational concepts necessary to understand the operation of PMMs, while the technology section addresses various applications, like precise biological and chemical sensors, cloaking devices for several frequency ranges, nanoscale photovoltaics, experimental optical computing components, and superlenses that can surpass the diffraction limit of conventional optics
Characterizing Round Spheres Using Half-Geodesics
A half-geodesic is a closed geodesic realizing the distance between any pair
of its points. All geodesics in a round sphere are half-geodesics. Conversely,
this note establishes that Riemannian spheres with all geodesics closed and
sufficiently many half-geodesics are round
Positively curved manifolds with large spherical rank
Rigidity results are obtained for Riemannian -manifolds with and spherical rank at least . Conjecturally, all such
manifolds are locally isometric to a round sphere or complex projective space
with the (symmetric) Fubini--Study metric. This conjecture is verified in all
odd dimensions, for metrics on -spheres when , for Riemannian
manifolds satisfying the Raki\'c duality principle, and for K\"ahlerian
manifolds.Comment: 33 page
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