1,377 research outputs found
Nonlinear Temporal Dynamics of Strongly Coupled Quantum Dot-Cavity System
We theoretically analyze and simulate the temporal dynamics of strongly
coupled quantum dot-cavity system driven by a resonant laser pulse. We observe
the signature of Rabi oscillation in the time resolved response of the system
(i.e., in the numerically calculated cavity output), derive simplified linear
and non-linear semi-classical models that approximate well the system's
behavior in the limits of high and low power drive pulse, and describe the role
of quantum coherence in the exact dynamics of the system. Finally, we also
present experimental data showing the signature of the Rabi oscillation in time
domain
Dynamics of short pressure probes
Report presents practical information for incorporating particle impact protection features and average total pressure measurement into probe design while optimizing probe transient response. Computer program calculates probe response, based on Bergh-Tijdeman equation
The infinite line pressure probe
The infinite line pressure probe provides a means for measuring high frequency fluctuating pressures in difficult environments. A properly designed infinite line probe does not resonate; thus its frequency response is not limited by acoustic resonance in the probe tubing, as in conventional probes. The characteristics of infinite line pressure probes are reviewed and some applications in turbine engine research are described. A probe with a flat-oval cross section, permitting a constant-impedance pressure transducer installation, is described. Techniques for predicting the frequency response of probes with both circular and flat-oval cross sections are also cited
Sinusoidal-pressure generator for testing dynamic pressure probes
Generator can produce sinusoidal pressures at frequencies from 300 to 5000 Hz and peak-to-peak amplitudes up to 5.6 lbs/sq in. Amplitude and phase-angle measurements made at various frequencies are compared with measurements from a piezoelectric transducer mounted flush with the resonant tube wall
Revision 1 Size and position of the healthy meniscus, and its Correlation with sex, height, weight, and bone area- a cross-sectional study
<p>Abstract</p> <p>Background</p> <p>Meniscus extrusion or hypertrophy may occur in knee osteoarthritis (OA). However, currently no data are available on the position and size of the meniscus in asymptomatic men and women with normal meniscus integrity.</p> <p>Methods</p> <p>Three-dimensional coronal DESSwe MRIs were used to segment and quantitatively measure the size and position of the medial and lateral menisci, and their correlation with sex, height, weight, and tibial plateau area. 102 knees (40 male and 62 female) were drawn from the Osteoarthritis Initiative "non-exposed" reference cohort, including subjects without symptoms, radiographic signs, or risk factors for knee OA. Knees with MRI signs of meniscus lesions were excluded.</p> <p>Results</p> <p>The tibial plateau area was significantly larger (p < 0.001) in male knees than in female ones (+23% medially; +28% laterally), as was total meniscus surface area (p < 0.001, +20% medially; +26% laterally). Ipsi-compartimental tibial plateau area was more strongly correlated with total meniscus surface area in men (r = .72 medially; r = .62 laterally) and women (r = .67; r = .75) than contra-compartimental or total tibial plateau area, body height or weight. The ratio of meniscus versus tibial plateau area was similar between men and women (p = 0.22 medially; p = 0.72 laterally). Tibial coverage by the meniscus was similar between men and women (50% medially; 58% laterally), but "physiological" medial meniscal extrusion was greater in women (1.83 ± 1.06mm) than in men (1.24mm ± 1.18mm; p = 0.011).</p> <p>Conclusions</p> <p>These data suggest that meniscus surface area strongly scales with (ipsilateral) tibial plateau area across both sexes, and that tibial coverage by the meniscus is similar between men and women.</p
Fabrication and characterization of high quality factor silicon nitride nanobeam cavities
Si3N4 is an excellent material for applications of nanophotonics at visible
wavelengths due to its wide bandgap and moderately large refractive index (n
2.0). We present the fabrication and characterization of Si3N4
photonic crystal nanobeam cavities for coupling to diamond nanocrystals and
Nitrogen-Vacancy centers in a cavity QED system. Confocal
micro-photoluminescence analysis of the nanobeam cavities demonstrates quality
factors up to Q ~ 55,000, which is limited by the resolution of our
spectrometer. We also demonstrate coarse tuning of cavity resonances across the
600-700nm range by lithographically scaling the size of fabricated devices.
This is an order of magnitude improvement over previous SiNx cavities at this
important wavelength range
Genuine Counterfactual Communication with a Nanophotonic Processor
In standard communication information is carried by particles or waves.
Counterintuitively, in counterfactual communication particles and information
can travel in opposite directions. The quantum Zeno effect allows Bob to
transmit a message to Alice by encoding information in particles he never
interacts with. The first suggested protocol not only required thousands of
ideal optical components, but also resulted in a so-called "weak trace" of the
particles having travelled from Bob to Alice, calling the scalability and
counterfactuality of previous proposals and experiments into question. Here we
overcome these challenges, implementing a new protocol in a programmable
nanophotonic processor, based on reconfigurable silicon-on-insulator waveguides
that operate at telecom wavelengths. This, together with our telecom
single-photon source and highly-efficient superconducting nanowire
single-photon detectors, provides a versatile and stable platform for a
high-fidelity implementation of genuinely trace-free counterfactual
communication, allowing us to actively tune the number of steps in the Zeno
measurement, and achieve a bit error probability below 1%, with neither
post-selection nor a weak trace. Our demonstration shows how our programmable
nanophotonic processor could be applied to more complex counterfactual tasks
and quantum information protocols.Comment: 6 pages, 4 figure
Changes in knee joint load indices from before to 12 months after arthroscopic partial meniscectomy:a prospective cohort study
Patients undergoing arthroscopic partial meniscectomy (APM) are at increased risk of knee osteoarthritis (OA). Meniscal damage and/or surgery may alter knee joint loading to increase OA risk. We investigated changes in knee joint loading following medial APM surgery, compared with the contra-lateral leg
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