927 research outputs found
Response to Shayah and Coatesworth
Full assessment of snoring should involve general and local factors which contribute to the patient's complaint, such as any history of apnoea attacks, high body mass index, reflux, smoking, alcohol consumption, uvulasize and laxity of soft palate, collar size and base of tongue. The paper did not clearly identify the potential importance of these factors
Recommended from our members
A delta configured auxiliary resonant snubber inverter
A delta ({Delta}) configured auxiliary resonant snubber inverter is developed to overcome the voltage floating problem in a wye (Y) configured resonant snubber inverter. The proposed inverter is to connect auxiliary resonant branches between phase outputs to avoid a floating point voltage which may cause over-voltage failure of the auxiliary switches. Each auxiliary branch consists of a resonant inductor and a reverse blocking auxiliary switch. Instead of using an anti-paralleled diode to allow resonant current to flow in the reverse direction, as in the Y-configured version, the resonant branch in the {Delta}-configured version must block the negative voltage, typically done by a series diode. This paper shows single-phase and three-phase versions of {Delta}-configured resonant snubber inverters and describes in detail the operating principle of a single-phase version. The extended three-phase version is proposed with non-adjacent state space vector modulation. For hardware implementation, a single-phase 1-kW unit and a three-phase 100-kW unit were built to prove the concept. Experimental results show the superiority of the proposed topology
Materials for stem cell factories of the future
The materials community is now identifying polymeric substrates that could permit translation of human pluripotent stem cells (hPSCs) from lab-based research to industrial scale biomedicine. Well defined materials are required to allow cell banking and to provide the raw material for reproducible differentiation into lineages for large scale drug screening programs and clinical use, wherein >1 billion cells for each patient are needed to replace losses during heart attack, multiple sclerosis and diabetes. Producing this number of cells for one patient is challenging and a rethink is needed to scalable technology with the potential to meet the needs of millions of patients a year. Here we consider the role of materials discovery, an emerging area of materials chemistry that is in a large part driven by the challenges posed by biologists to materials scientists1-4
Understanding person acquisition using an interactive activation and competition network
Face perception is one of the most developed visual skills that humans display, and recent work has attempted to examine the mechanisms involved in face perception through noting how neural networks achieve the same performance. The purpose of the present paper is to extend this approach to look not just at human face recognition, but also at human face acquisition. Experiment 1 presents empirical data to describe the acquisition over time of appropriate representations for newly encountered faces. These results are compared with those of Simulation 1, in which a modified IAC network capable of modelling the acquisition process is generated. Experiment 2 and Simulation 2 explore the mechanisms of learning further, and it is demonstrated that the acquisition of a set of associated new facts is easier than the acquisition of individual facts in isolation of one another. This is explained in terms of the advantage gained from additional inputs and mutual reinforcement of developing links within an interactive neural network system. <br/
The Effects of Atmospheric Dispersion on High-Resolution Solar Spectroscopy
We investigate the effects of atmospheric dispersion on observations of the
Sun at the ever-higher spatial resolutions afforded by increased apertures and
improved techniques. The problems induced by atmospheric refraction are
particularly significant for solar physics because the Sun is often best
observed at low elevations, and the effect of the image displacement is not
merely a loss of efficiency, but the mixing of information originating from
different points on the solar surface. We calculate the magnitude of the
atmospheric dispersion for the Sun during the year and examine the problems
produced by this dispersion in both spectrographic and filter observations. We
describe an observing technique for scanning spectrograph observations that
minimizes the effects of the atmospheric dispersion while maintaining a regular
scanning geometry. Such an approach could be useful for the new class of
high-resolution solar spectrographs, such as SPINOR, POLIS, TRIPPEL, and ViSP
Pair creation of anti-de Sitter black holes on a cosmic string background
We analyze the quantum process in which a cosmic string breaks in an anti-de
Sitter (AdS) background, and a pair of charged or neutral black holes is
produced at the ends of the strings. The energy to materialize and accelerate
the pair comes from the strings tension. In an AdS background this is the only
study done in the process of production of a pair of correlated black holes
with spherical topology. The acceleration of the produced black holes is
necessarily greater than (|L|/3)^(1/2), where L<0 is the cosmological constant.
Only in this case the virtual pair of black holes can overcome the attractive
background AdS potential well and become real. The instantons that describe
this process are constructed through the analytical continuation of the AdS
C-metric. Then, we explicitly compute the pair creation rate of the process,
and we verify that (as occurs with pair creation in other backgrounds) the pair
production of nonextreme black holes is enhanced relative to the pair creation
of extreme black holes by a factor of exp(Area/4), where Area is the black hole
horizon area. We also conclude that the general behavior of the pair creation
rate with the mass and acceleration of the black holes is similar in the AdS,
flat and de Sitter cases, and our AdS results reduce to the ones of the flat
case when L=0.Comment: 13 pages, 3 figures, ReVTeX
Interaction of Nearly-Inviscid, Multi-mode Faraday Waves and Mean Flows
Faraday waves [1] are gravity-capillary waves that are excited on the surface of a fluid when its container is vibrated vertically and the vertical acceleration exceeds a threshold value. These waves have received much attention in the literature both as a basic fluid dynamical problem and as a paradigm of a pattern-forming system [2-4]. Unfortunately, in the low viscosity limit, there are several basic issues that remain unresolved, particularly in connection with the generation of mean flows in the bulk. The viscous part of these flows (also called streaming flow or acoustic streaming) is driven by the oscillatory boundary layers attached to the solid walls and the free surface by well-known mechanisms first uncovered by Schlichting [5] and Longuet-Higgins [6]. This mean flow has been shown recently to affect the dynamics of the primary waves at leading order in a related, laterally vibrated system [7]. This is somewhat similar to the effect of an internal circulation on surface wave dynamics in drops [8]
Some general properties of the renormalized stress-energy tensor for static quantum states on (n+1)-dimensional spherically symmetric black holes
We study the renormalized stress-energy tensor (RSET) for static quantum
states on (n+1)-dimensional, static, spherically symmetric black holes. By
solving the conservation equations, we are able to write the stress-energy
tensor in terms of a single unknown function of the radial co-ordinate, plus
two arbitrary constants. Conditions for the stress-energy tensor to be regular
at event horizons (including the extremal and ``ultra-extremal'' cases) are
then derived using generalized Kruskal-like co-ordinates. These results should
be useful for future calculations of the RSET for static quantum states on
spherically symmetric black hole geometries in any number of space-time
dimensions.Comment: 9 pages, no figures, RevTeX4, references added, accepted for
publication in General Relativity and Gravitatio
Measurement of a small atmospheric ratio
From an exposure of 25.5~kiloton-years of the Super-Kamiokande detector, 900
muon-like and 983 electron-like single-ring atmospheric neutrino interactions
were detected with momentum MeV/, MeV/, and
with visible energy less than 1.33 GeV. Using a detailed Monte Carlo
simulation, the ratio was measured to be , consistent with previous results from the
Kamiokande, IMB and Soudan-2 experiments, and smaller than expected from
theoretical models of atmospheric neutrino production.Comment: 14 pages with 5 figure
- …