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Electromagnetically induced left-handedness in a dense gas of three-level atoms
No full textWe discuss how a three-level system can be used to change the frequency-dependent magnetic permeability of an atomic gas to be significantly different from 1. We derive the conditions for such a scheme to be successful and briefly discuss the resulting macroscopic electrodynamics. We find that it may be possible to obtain left-handed electrodynamics for an atomic gas using three atomic levels
Optimal auctions with simultaneous and costly participation
No full textWe study the optimal auction problem with participation costs in the symmetric independent private values setting, where bidders know their valuations when they make independent participation decisions. After characterizing the optimal auction in terms of participation cutoffs, we provide an example where it is asymmetric. We then investigate when the optimal auction will be symmetric/asymmetric and the nature of possible asymmetries. We also show that, under some conditions, the seller obtains her maximal profit in an (asymmetric) equilibrium of an anonymous second price auction. In general, the seller can also use non-anonymous auctions that resemble the ones that are actually observed in practice
Retention during capsule endoscopy: Is it a real problem in routine practice?
No full textObjective This study evaluated the risks and outcomes of capsule retention during capsule endoscopy (CE) for investigating small bowel disease. Capsule retention is the most serious complication of CE. Methods Before CE, the gastrointestinal tract was evaluated for blockages with computerized tomography. Analysis of CE was made retrospectively. Results Capsule endoscopy was used to investigate obscure bleeding (90.2%; n=324) or other symptoms (9.8%; n=35). The capsule retention rate was 11/359 (3.1%); it was retained in a malignant lesion area (adenocarcinoma or melanoma) in two patients (18.2%), in the small bowel in an ulcerated area in five patients (45.5%), and in the oesophagus/stomach in four patients (36.4%) due to dysmotility. None of the patients had symptoms of obstruction. Conclusions Scanning patients before CE did not predict capsule retention. Retention is a complication of CE, but occurs as a result of the underlying disease. The risk of retention is increased in patients with motility disorders, suspected small bowel ulcers or malignancies
Silicon microspheres - art. no. 61010K
No full textMorphology-dependent resonances are observed in silicon microspheres, both in the transmission and elastic scattering spectra in the O-band. Approximately 23% of the power is coupled out at the resonance wavelength. The highest observed quality factor for the morphology dependent resonances was on the order of 10(5). These resonances have a linewidth of 0.007 nm and a mode spacing of 0.19 nm
Droplet resonator based optofluidic microlasers
No full textAn SU-8 polymer microdisk resonator coated with a palladium (Pd) layer and coupled to a single-mode optical waveguide is used to as a hydrogen (H-2) gas sensor. In the presence of H2 a red shift is observed in the spectral positions of the microdisk whispering gallery modes (WGMs) due to the expansion in the Pd lattice. H-2 concentrations below the flammable limit (4%) down to 0.3% could be detected in nitrogen atmosphere at room temperature. For H-2 concentrations between 0.3 1%, WGM spectral positions shifted linearly with H-2 concentration at a rate of 32 pm/%H-2. Average response time of the devices was measured to be 50 s for 1% H-2. The proposed device concept can also be used to detect different chemical gases by using appropriate sensing layers
Hydrogenated amorphous silicon nitride based photonic light emitting devices
No full textWe have observed visible photoluninescence from hydrogenated amorphous silicon nitride (a-SiNx:H) as well as the enhancement and inhibition of this photoluninescence in a microcavity formed with metallic mirrors. The a-SSJx:H was grown both with and without ammonia. The photoluminescence of the a-SSNx:H grown without ammonia is red. The photoluminescence of the a-SiNx:H grown with ammonia is blue-green. In this paper, we report on the enhancement and inhibition of the photoluminescence from a half wavelength thick dielectric a-SiNx:H microcavity. The distributed Bragg reflector mirrors were fabricated using alternating pairs of quarter wavelength thick silicon oxide and silicon nitride. The photoluminescence is enhanced by at least an order of magnitude at the dielectric a-SiNx:H microcavity resonance at 710 nn. The minimum resonance linewidth is 6 nn, which corresponds to a quality factor of 118. The maximum rejection bandwidth is 150 nm. The enhancement and inhibition of the photoluminescence is understood by the modified photon density of states of the dielectric microcavity. The linewidth of the photoluminescence is also narrowed with respect to the linewidth of the bulk a-SiNx:H, again due to the presence of the electromagnetic modes of the dielectric microcavity. The resonance enhancement and inhibition of the photoluminescence in a-SiNx:H opens up a variety of possibilities for optoelectronic applications such as color flat panel displays or active resonant cavity enhanced devices for wavelength division multiplexing
DNABINDPROT: fluctuation-based predictor of DNA-binding residues within a network of interacting residues
No full textDNABINDPROT is designed to predict DNA-binding residues, based on the fluctuations of residues in high-frequency modes by the Gaussian network model. The residue pairs that display high mean-square distance fluctuations are analyzed with respect to DNA binding, which are then filtered with their evolutionary conservation profiles and ranked according to their DNA-binding propensities. If the analyses are based on the exact outcome of fluctuations in the highest mode, using a conservation threshold of 5, the results have a sensitivity, specificity, precision and accuracy of 9.3%, 90.5%, 18.1% and 78.6%, respectively, on a dataset of 36 unbound-bound protein structure pairs. These values increase up to 24.3%, 93.4%, 45.3% and 83.3% for the respective cases, when the neighboring two residues are considered. The relatively low sensitivity appears with the identified residues being selective and susceptible more for the binding core residues rather than all DNA-binding residues. The predicted residues that are not tagged as DNA-binding residues are those whose fluctuations are coupled with DNA-binding sites. They are in close proximity as well as plausible for other functional residues, such as ligand and protein-protein interaction sites