682 research outputs found
Internal wave propagation normal to a geostrophic current
It is shown that (i) internal gravity waves propagating along a horizontal density gradient in a uniformly rotating ocean can exist for a range of slightly smaller frequencies than is possible in the absence of such a gradient, (ii) such waves exhibit a phase difference from top to bottom, and (iii) they exchange energy with the geostrophic current, which balances the density-induced pressure gradient...
Nonlinear optomechanical paddle nanocavities
Nonlinear optomechanical coupling is the basis for many potential future
experiments in quantum optomechanics (e.g., quantum non-demolition
measurements, preparation of non-classical states), which to date have been
difficult to realize due to small non-linearity in typical optomechanical
devices. Here we introduce an optomechanical system combining strong nonlinear
optomechanical coupling, low mass and large optical mode spacing. This
nanoscale "paddle nanocavity" supports mechanical resonances with hundreds of
fg mass which couple nonlinearly to optical modes with a quadratic
optomechanical coupling coefficient MHz/nm, and a
two phonon to single photon optomechanical coupling rate Hz. This coupling relies on strong phonon-photon interactions in
a structure whose optical mode spectrum is highly non--degenerate. Nonlinear
optomechanical readout of thermally driven motion in these devices should be
observable for T mK, and measurement of phonon shot noise is
achievable. This shows that strong nonlinear effects can be realized without
relying on coupling between nearly degenerate optical modes, thus avoiding
parasitic linear coupling present in two mode systems.Comment: 8 pages, 5 figure
Design and experimental demonstration of optomechanical paddle nanocavities
We present the design, fabrication and initial characterization of a paddle
nanocavity consisting of a suspended sub-picogram nanomechanical resonator
optomechanically coupled to a photonic crystal nanocavity. The optical and
mechanical properties of the paddle nanocavity can be systematically designed
and optimized, and key characteristics including mechanical frequency easily
tailored. Measurements under ambient conditions of a silicon paddle nanocavity
demonstrate an optical mode with quality factor ~ 6000 near 1550 nm, and
optomechanical coupling to several mechanical resonances with frequencies
~ 12-64 MHz, effective masses ~ 350-650 fg, and
mechanical quality factors ~ 44-327. Paddle nanocavities are promising
for optomechanical sensing and nonlinear optomechanics experiments.Comment: 5 pages, 4 figure
The development of a measure of social care outcome for older people. Funded/commissioned by: Department of Health
An essential element of identifying Best Value and monitoring cost-effective care is to be able to identify the outcomes of care. In the field of health services, use of utility-based health related quality of life measures has become widespread, indeed even required. If, in the new era of partnerships, social care outcomes are to be valued and included we need to develop measures that reflect utility or welfare gain from social care interventions. This paper reports on a study, commissioned as part of the Department of Health’s Outcomes of Social Care for Adults Initiative, that developed an instrument and associated utility indexes that provide a tool for evaluating social care interventions in both a research and service setting. Discrete choice conjoint analysis used to derive utility weights provided us with new insights into the relative importance of the core domains of social care to older people. Whilst discrete choice conjoint analysis is being increasingly used in health economics, this is the first study that has attempted to use it to derive a measure of outcome
Dissipative and Dispersive Optomechanics in a Nanocavity Torque Sensor
Dissipative and dispersive optomechanical couplings are experimentally
observed in a photonic crystal split-beam nanocavity optimized for detecting
nanoscale sources of torque. Dissipative coupling of up to approximately
MHz/nm and dispersive coupling of GHz/nm enable measurements of sub-pg
torsional and cantilever-like mechanical resonances with a thermally-limited
torque detection sensitivity of 1.2 in ambient conditions and 1.3 in low vacuum. Interference between
optomechanical coupling mechanisms is observed to enhance detection sensitivity
and generate a mechanical-mode-dependent optomechanical wavelength response.Comment: 11 pages, 6 figure
Evaluation of Polymorphic Locus Sequence Typing for Candida glabrata Epidemiology.
The opportunistic yeastCandida glabratais increasingly refractory to antifungal treatment or prophylaxis and relatedly is increasingly implicated in health care-associated infections. To elucidate the epidemiology of these infections, strain typing is required. Sequence-based typing provides multiple advantages over length-based methods, such as pulsed-field gel electrophoresis (PFGE); however, conventional multilocus sequence typing (targeting 6 conserved loci) and whole-genome sequencing are impractical for routine use. A commercial sequence-based typing service forC. glabratathat targets polymorphic tandem repeat-containing loci has recently been developed. These CgMT-J and CgMT-M services were evaluated with 56 epidemiologically unrelated isolates, 4 to 7 fluconazole-susceptible or fluconazole-resistant isolates from each of 5 center A patients, 5 matched pairs of fluconazole-susceptible/resistant isolates from center B patients, and 7 isolates from a center C patient who responded to then failed caspofungin therapy. CgMT-J and CgMT-M generated congruent results, resolving isolates into 24 and 20 alleles, respectively. Isolates from all but one of the center A patients shared the same otherwise rare alleles, suggesting nosocomial transmission. Unexpectedly, Pdr1 sequencing showed that resistance arose independently in each patient. Similarly, most isolates from center B also clustered together; however, this may reflect a dominant clone since their alleles were shared by multiple unrelated isolates. Although distinguishable by their echinocandin susceptibilities, all isolates from the center C patient shared alleles, in agreement with the previously reported relatedness of these isolates based on PFGE. Finally, we show how phylogenetic clusters can be used to provide surrogate parents to analyze the mutational basis for antifungal resistance
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