7,508 research outputs found
Modified mean curvature flow of star-shaped hypersurfaces in hyperbolic space
We define a new version of modified mean curvature flow (MMCF) in hyperbolic
space , which interestingly turns out to be the natural
negative -gradient flow of the energy functional defined by De Silva and
Spruck in \cite{DS09}. We show the existence, uniqueness and convergence of the
MMCF of complete embedded star-shaped hypersurfaces with fixed prescribed
asymptotic boundary at infinity. As an application, we recover the existence
and uniqueness of smooth complete hypersurfaces of constant mean curvature in
hyperbolic space with prescribed asymptotic boundary at infinity, which was
first shown by Guan and Spruck.Comment: 26 pages, 3 figure
Tunable strong plasmon-exciton coupling based on borophene and deep subwavelength perovskite grating
Two-dimensional materials support deeply confined and tunable plasmonic
modes, which have great potential for achieving device miniaturization and
flexible manipulation. In this paper, we propose a diffraction-unlimited system
composed of borophene layer and perovskite grating to investigate the strong
coupling between the borophene guiding plasmon (BGP) and perovskite exciton
(PE) mode. The resonant energy of BGP mode could be electrically tuned to match
the energy of PE mode, and a remarkable Rabi splitting is attained under
zero-detuning condition. The splitting energy could reach 230 meV due to the
strong field enhancement provided by BGP mode. Consequently, an active
reflective phase modulation with 1.76{\pi} range is achieved by dynamically
manipulating the detuning. Furthermore, by increasing the distance between the
borophene layer and perovskite grating, a parity-time symmetry breaking could
be observed with the vanished energy splitting. Our results deepen the
understanding of light-matter interaction at the sub-wavelength scale and
provide a guideline for designing active plasmonic devices.Comment: 9 pages, 4 figure
On Type-Aware Entity Retrieval
Today, the practice of returning entities from a knowledge base in response
to search queries has become widespread. One of the distinctive characteristics
of entities is that they are typed, i.e., assigned to some hierarchically
organized type system (type taxonomy). The primary objective of this paper is
to gain a better understanding of how entity type information can be utilized
in entity retrieval. We perform this investigation in an idealized "oracle"
setting, assuming that we know the distribution of target types of the relevant
entities for a given query. We perform a thorough analysis of three main
aspects: (i) the choice of type taxonomy, (ii) the representation of
hierarchical type information, and (iii) the combination of type-based and
term-based similarity in the retrieval model. Using a standard entity search
test collection based on DBpedia, we find that type information proves most
useful when using large type taxonomies that provide very specific types. We
provide further insights on the extensional coverage of entities and on the
utility of target types.Comment: Proceedings of the 3rd ACM International Conference on the Theory of
Information Retrieval (ICTIR '17), 201
Formation of Nanofoam carbon and re-emergence of Superconductivity in compressed CaC6
Pressure can tune material's electronic properties and control its quantum
state, making some systems present disconnected superconducting region as
observed in iron chalcogenides and heavy fermion CeCu2Si2. For CaC6
superconductor (Tc of 11.5 K), applying pressure first Tc increases and then
suppresses and the superconductivity of this compound is eventually disappeared
at about 18 GPa. Here, we report a theoretical finding of the re-emergence of
superconductivity in heavily compressed CaC6. The predicted phase III (space
group Pmmn) with formation of carbon nanofoam is found to be stable at wide
pressure range with a Tc up to 14.7 K at 78 GPa. Diamond-like carbon structure
is adhered to the phase IV (Cmcm) for compressed CaC6 after 126 GPa, which has
bad metallic behavior, indicating again departure from superconductivity.
Re-emerged superconductivity in compressed CaC6 paves a new way to design
new-type superconductor by inserting metal into nanoporous host lattice.Comment: 31 pages, 12 figures, and 4 table
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