245 research outputs found
Restriction of salt intake and other dietary modifications for the treatment of Meniere's disease or syndrome
This is the protocol for a review and there is no abstract. The objectives are as follows:
To determine the effectiveness of dietary modifications, specifically restriction of salt, alcohol and caffeine intake, in patients suffering from Ménière's disease or syndrome. We will also review other dietary modifications but we will limit analysis of these studies to a narrative review
Photon assisted tunneling in pairs of silicon donors
Shallow donors in silicon are favorable candidates for the implementation of solid-state quantum computer architectures because of the promising combination of atomiclike coherence properties and scalability from the semiconductor manufacturing industry. Quantum processing schemes require (among other things) controlled information transfer for readout. Here we demonstrate controlled electron tunneling at 10 K from P to Sb impurities and vice versa with the assistance of resonant terahertz photons
Population inversion in optically pumped asymmetric quantum well terahertz lasers
Intersubband carrier lifetimes and population ratios are calculated for three- and four-level optically pumped terahertz laser structures. Laser operation is based on intersubband transitions between the conduction band states of asymmetric GaAs-Ga(1 – x)Al(x)As quantum wells. It is shown that the carrier lifetimes in three-level systems fulfill the necessary conditions for stimulated emission only at temperatures below 200 K. The addition of a fourth level, however, enables fast depopulation of the lower laser level by resonant longitudinal optical phonon emission and thus offers potential for room temperature laser operation. © 1997 American Institute of Physics
Near-Infrared Light Curves of the Black Hole Binary A0620-00
We measured the near-infrared orbital light curve of the black hole binary
A0620-00 in 1995 and 1996. The light curves show an asymmetric, double-humped
modulation with extra emission in the peak at orbital phase 0.75. There were no
significant changes in the shape of the light curve over the one-year
observation period. There were no sharp dips in the light curves nor reversals
of the asymmetry between the two peaks as seen in earlier observations. The
light curves are well fit by models incorporating ellipsoidal variations from
the mass-losing K-type star plus a beamed bright spot on the accretion disk
around the compact star. The long-term stability of the light curve shape rules
out superhumps and star spots as sources of asymmetry when we observed
A0620-00. The ellipsoidal variations yield a lower limit i >= 38 deg on the
orbital inclination. The light curves show no eclipse features, which places an
upper limit i <= 75 deg. This range of inclinations constrains the mass of the
compact object to 3.3 < M_1 < 13.6 Msun. The light curves do not further
constrain the orbital inclination because the contribution of the accretion
disk to the observed flux is unknown. We argue that a previous attempt to
measure the near-infrared flux from the accretion disk using the dilution of
the 12CO(2,0) bandhead in the spectrum of the K star is not reliable because
the band strength depends strongly on surface gravity.Comment: Accepted for publication in the Astronomical Journal. 17 pages, 4
figures. Prepared using AASTEX V. 5.
Relationships between hearing loss and hearing aid usage in real world
Many hearing aids are fitted with multiple programs that the user can choose between in different situations. In the H2020 EVOTION project hundreds of hearing aid users were fitted according to their audiogram with Oticon VAC rationale with four adaptive programs that differed in the noise management profile. The programs differed on how much the noise was attenuated and the threshold at which the device started to remove noise. The hearing aids also transmitted continuous data about the sound environment and the operation of the hearing aid to a dedicated app on a smartphone. The participants had a wide range of hearing losses and was recruited from amongst new and experienced hearing aid users in six different clinics in UK, Greece, and Denmark. The data from the hearing aid users was collected for up to a year to investigate relationships between clinical factors and usage patterns. The data enables a detailed investigation of the complexity of sound environments throughout the day, relation between complexity as function of time to the clinical factors including and beyond the audiogram
Band anticrossing in GaNxSb1–x
Fourier transform infrared absorption measurements are presented from the dilute nitride semiconductor GaNSb with nitrogen incorporations between 0.2% and 1.0%. The divergence of transitions from the valence band to E– and E+ can be seen with increasing nitrogen incorporation, consistent with theoretical predictions. The GaNSb band structure has been modeled using a five-band k·p Hamiltonian and a band anticrossing fitting has been obtained using a nitrogen level of 0.78 eV above the valence band maximum and a coupling parameter of 2.6 eV
Band gap reduction in GaNSb alloys due to the anion mismatch
The structural and optoelectronic properties in GaNxSb1–x alloys (0<=x<0.02) grown by molecular-beam epitaxy on both GaSb substrates and AlSb buffer layers on GaAs substrates are investigated. High-resolution x-ray diffraction (XRD) and reciprocal space mapping indicate that the GaNxSb1–x epilayers are of high crystalline quality and the alloy composition is found to be independent of substrate, for identical growth conditions. The band gap of the GaNSb alloys is found to decrease with increasing nitrogen content from absorption spectroscopy. Strain-induced band-gap shifts, Moss-Burstein effects, and band renormalization were ruled out by XRD and Hall measurements. The band-gap reduction is solely due to the substitution of dilute amounts of highly electronegative nitrogen for antimony, and is greater than observed in GaNAs with the same N content
Photoluminescence spectroscopy of bandgap reduction in dilute InNAs alloys
Photoluminescence (PL) has been observed from dilute InNxAs1–x epilayers grown by molecular-beam epitaxy. The PL spectra unambiguously show band gap reduction with increasing N content. The variation of the PL spectra with temperature is indicative of carrier detrapping from localized to extended states as the temperature is increased. The redshift of the free exciton PL peak with increasing N content and temperature is reproduced by the band anticrossing model, implemented via a (5×5) k·p Hamiltonian
SCUBA Mapping of Spitzer c2d Small Clouds and Cores
We present submillimeter observations of dark clouds that are part of the
Spitzer Legacy Program, From Molecular Cores to Planet-Forming Disks (c2d). We
used the Submillimetre Common User's Bolometer Array to map the regions
observed by Spitzer by the c2d program to create a census of dense molecular
cores including data from the infrared to the submillimeter. In this paper, we
present the basic data from these observations: maps, fluxes, and source
attributes. We also show data for an object just outside the Perseus cloud that
was serendipitously observed in our program. We propose that this object is a
newly discovered, evolved protostar.Comment: 37 pages, accepted to The Astronomical Journa
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