5,806 research outputs found
Band structure of honeycomb photonic crystal slabs
Two-dimensional (2D) honeycomb photonic crystals with cylinders and
connecting walls have the potential to have a large full band gap. In
experiments, 2D photonic crystals do not have an infinite height, and
therefore, we investigate the effects of the thickness of the walls, the height
of the slabs and the type of the substrates on the photonic bands and gap maps
of 2D honeycomb photonic crystal slabs. The band structures are calculated by
the plane wave expansion method and the supercell approach. We find that the
slab thickness is a key parameter affecting the band gap size while on the
other hand the wall thickness hardly affact the gap size. For symmetric
photonic crystal slabs with lower dielectric claddings, the height of the slabs
needs to be sufficiently large to maintain a band gap. For asymmetric
claddings, the projected band diagrams are similar to that of symmetric slabs
as long as the dielectric constants of the claddings do not differ greatly.Comment: Accepted for publication in Journal of Applied Physic
Enhancing entanglement detection of quantum optical frequency combs via stimulated emission
We investigate the performance of a certain nonclassicality identifier,
expressed via integrated second-order intensity moments of optical fields, in
revealing bipartite entanglement of quantum-optical frequency combs (QOFCs),
which are generated in both spontaneous and stimulated parametric
down-conversion processes. We show that, by utilizing that nonclassicality
identifier, one can well identify the entanglement of the QOFC directly from
the experimentally measured intensity moments without invoking any state
reconstruction techniques or homodyne detection. Moreover, we demonstrate that
the stimulated generation of the QOFC improves the entanglement detection of
these fields with the nonclassicality identifier. Additionally, we show that
the nonclassicality identifier can be expressed in a factorized form of
detectors quantum efficiencies and the number of modes, if the QOFC consists of
many copies of the same two-mode twin beam. As an example, we apply the
nonclassicality identifier to two specific types of QOFC, where: (i) the QOFC
consists of many independent two-mode twin beams with non-overlapped spatial
frequency modes, and (ii) the QOFC contains entangled spatial frequency modes
which are completely overlapped, i.e., each mode is entangled with all the
remaining modes in the system. We show that, in both cases, the nonclassicality
identifier can reveal bipartite entanglement of the QOFC including noise, and
that it becomes even more sensitive for the stimulated processes.Comment: 11 p., 8 fig
-degeneration and -lemma
For a double complex , we show that if it satisfies the
-lemma and the spectral sequence induced by does
not degenerate at , then it degenerates at . We apply this result to
prove the degeneration at of a Hodge-de Rham spectral sequence on compact
bi-generalized Hermitian manifolds that satisfy a version of -lemma
Nonlinear Near-Field Microwave Microscope For RF Defect Localization in Superconductors
Niobium-based Superconducting Radio Frequency (SRF) cavity performance is
sensitive to localized defects that give rise to quenches at high accelerating
gradients. In order to identify these material defects on bulk Nb surfaces at
their operating frequency and temperature, it is important to develop a new
kind of wide bandwidth microwave microscopy with localized and strong RF
magnetic fields. By taking advantage of write head technology widely used in
the magnetic recording industry, one can obtain ~200 mT RF magnetic fields,
which is on the order of the thermodynamic critical field of Nb, on submicron
length scales on the surface of the superconductor. We have successfully
induced the nonlinear Meissner effect via this magnetic write head probe on a
variety of superconductors. This design should have a high spatial resolution
and is a promising candidate to find localized defects on bulk Nb surfaces and
thin film coatings of interest for accelerator applications.Comment: 4 pages, 6 figures Journal-ref: 2010 Applied Superconductivity
Conferenc
Development of Dual Band Dual Polarized Patch Antenna System for Indoor Application
Wireless communication systems have received increased interests in recent years , also increases demand of indoor wireless networks. Many buildings and malls have been installed with indoor wireless networks consisting of numerous indoor base station antennas. This paper presents dual band dual polarized patch antenna system for indoor application The substrate material FR4 is selected for microstrip patch antenna design. An analysis of the return loss, gain, axial ratio of the proposed antenna is carried out using ADS (Advanced Design System) software. The result shows that return loss ,gain and axial ratio at 2.4 GHz frequency respectively -28 dB ,3.662dBi,2.821 dB achieved and at 2.6 GHz frequency -10dB ,2.295,dBi,3.358 dB is achieved
Visual and Non -- Visual Elements Found in "Bali Safari Park" Brochure
This research was mainly aimed at finding out the visual and non-visual element and their meanings in Bali Safari Park brochure. The brochure was chosen because there were various types of pictures and texts. The data were collected by finding and reading that brochure and note taking the data from Bali Safari Park brochure using the observation method. The method that was used in analyzing the data was a descriptive method. The presenting the data was formal method by using symbols, pictures or images to illustrate the phenomena found in the data. The result of this research showed that there were the visual and non-visual elements found in Bali Safari Park brochure. The visual and non-visual elements were in the form of pictures, the logo, symbol, colors, the pictures of fonts, phrases, and sentences. Those forms were found in headline, body copy, signature line, and standing details. The types of meaning found in the visual and non-visual elements were affective meaning, conceptual meaning, and denotative meaning.
Keywords: discourse analysis, visual and non-visual elements, Bali Safari Par
Economics of neuraminidase inhibitor stock piling for pandemic influenza, Singapore.
We compared strategies for stock piling neuraminidase inhibitors to treat and prevent influenza in Singapore. Cost-benefit and cost-effectiveness analyses, with Monte Carlo simulations, were used to determine economic outcomes. A pandemic in a population of 4.2 million would result in an estimated 525-1,775 deaths, 10,700-38,600 hospitalization days, and economic costs of 0.7 dollars to 2.2 billion Singapore dollars. The treatment-only strategy had optimal economic benefits: stock piles of antiviral agents for 40% of the population would save an estimated 418 lives and 414 million dollars, at a cost of 52.6 million dollars per shelf-life cycle of the stock pile. Prophylaxis was economically beneficial in high-risk subpopulations, which account for 78% of deaths, and in pandemics in which the death rate was >0.6%. Prophylaxis for pandemics with a 5% case-fatality rate would save 50,000 lives and 81 billion dollars. These models can help policymakers weigh the options for pandemic planning
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