1,401 research outputs found
Clocked Atom Delivery to a Photonic Crystal Waveguide
Experiments and numerical simulations are described that develop quantitative
understanding of atomic motion near the surfaces of nanoscopic photonic crystal
waveguides (PCWs). Ultracold atoms are delivered from a moving optical lattice
into the PCW. Synchronous with the moving lattice, transmission spectra for a
guided-mode probe field are recorded as functions of lattice transport time and
frequency detuning of the probe beam. By way of measurements such as these, we
have been able to validate quantitatively our numerical simulations, which are
based upon detailed understanding of atomic trajectories that pass around and
through nanoscopic regions of the PCW under the influence of optical and
surface forces. The resolution for mapping atomic motion is roughly 50 nm in
space and 100 ns in time. By introducing auxiliary guided mode (GM) fields that
provide spatially varying AC-Stark shifts, we have, to some degree, begun to
control atomic trajectories, such as to enhance the flux into to the central
vacuum gap of the PCW at predetermined times and with known AC-Stark shifts.
Applications of these capabilities include enabling high fractional filling of
optical trap sites within PCWs, calibration of optical fields within PCWs, and
utilization of the time-dependent, optically dense atomic medium for novel
nonlinear optical experiments
The power of cross-functional teams in driving total quality
Garrett Canada, a Division of Allied-Signal Aerospace Canada, has been a member of the Canadian aerospace industry for 40 years. Although Garrett Canada has always been a profitable division with a solid market share, the changing and turbulent business environment and globalization of the aerospace industry has created new demands and challenges. The marketplace is demanding faster introduction of new products, as well as shorter leadtimes for repairs and spares. It was recognized that reducing cycle times for new products and for ongoing production would not only satisfy our customers, it would also enhance our business performance through reduced inventories, lower past due, and more responsiveness to change. It was evident that drastic function changes were required if we were to maintain our position as a premier aerospace supplier. The challenge was to convert a stable, somewhat slow-paced work environment with strong functional boundaries into a boundaryless world class team functioning in a total quality environment and focused on customer satisfaction. Complete and uncompromised customer satisfaction has become our driving force, with Total Quality being our engine to continuously improve our processes and increase our speed. The way in which this transition has been brought about is the subject of this presentation
A comparison of single-cycle versus multiple-cycle proof testing strategies
An evaluation of single-cycle and multiple-cycle proof testing (MCPT) strategies for SSME components is described. Data for initial sizes and shapes of actual SSME hardware defects are analyzed statistically. Closed-form estimates of the J-integral for surface flaws are derived with a modified reference stress method. The results of load- and displacement-controlled stable crack growth tests on thin IN-718 plates with deep surface flaws are summarized. A J-resistance curve for the surface-cracked configuration is developed and compared with data from thick compact tension specimens. The potential for further crack growth during large unload/reload cycles is discussed, highlighting conflicting data in the literature. A simple model for ductile crack growth during MCPT based on the J-resistance curve is used to study the potential effects of key variables. The projected changes in the crack size distribution during MCPT depend on the interactions between several key parameters, including the number of proof cycles, the nature of the resistance curve, the initial crack size distribution, the component boundary conditions (load vs. displacement control), and the magnitude of the applied load or displacement. The relative advantages of single-cycle and multiple-cycle proof testing appear to be specific, therefore, to individual component geometry, material, and loading
High-Resolution Particle-In-Cell Simulations of Two-Dimensional Bernstein-Greene-Kruskal Modes
We present two dimensional (2D) particle-in-cell (PIC) simulations of 2D
Bernstein-Greene-Kruskal (BGK) modes, which are exact nonlinear steady-state
solutions of the Vlasov-Poisson equations, on a 2D plane perpendicular to a
background magnetic field, with a cylindrically symmetric electric potential
localized on the plane. PIC simulations are initialized using analytic electron
distributions and electric potentials from the theory. We confirm the validity
of such solutions using high-resolutions up to a 2048^2 grid. We show that the
solutions are dynamically stable for a stronger background magnetic field,
while keeping other parameters of the model fixed, but become unstable when the
field strength is weaker than a certain value. When a mode becomes unstable, we
observe that the instability begins with the excitation of azimuthal
electrostatic waves that ends with a spiral pattern
The placebo and nocebo effects on peak minute power during incremental arm crank ergometry
This is an Accepted Manuscript of an article published by Taylor & Francis Group in European Journal of Sport Science on 19 May 2014, available online: http://www.tandfonline.com/doi/abs/10.1080/17461391.2013.822564.This investigation aimed to explore the effects of inert sugar-free drinks described as either 'performance enhancing' (placebo) or 'fatigue inducing' (nocebo) on peak minute power (PMP;W) during incremental arm crank ergometry (ACE). Twelve healthy, non-specifically trained individuals volunteered to take part. A single-blind randomised controlled trial with repeated measures was used to assess for differences in PMP;W, oxygen uptake, heart rate (HR), minute ventilation, respiratory exchange ratio (RER) and subjective reports of local ratings of perceived exertion (LRPE) and central ratings of perceived exertion (CRPE), between three separate, but identical ACE tests. Participants were required to drink either 500 ml of a 'sports performance' drink (placebo), a 'fatigue-inducing' drink (nocebo) or water prior to exercise. The placebo caused a significant increase in PMP;W, and a significant decrease in LRPE compared to the nocebo (p=0.01; p=0.001) and water trials (p=0.01). No significant differences in PMP;W between the nocebo and water were found. However, the nocebo drink did cause a significant increase in LRPE (p=0.01). These results suggest that the time has come to broaden our understanding of the placebo and nocebo effects and their potential to impact sports performance.Peer reviewe
Cloning of the rice Xo1 resistance gene and interaction of the Xo1 protein with the defense-suppressing Xanthomonas effector Tal2h
The Xo1 locus in the heirloom rice variety Carolina Gold Select confers resistance to bacterial leaf streak and bacterial blight, caused by Xanthomonas oryzae pv. oryzicola and X. oryzae pv. oryzae, respectively. Resistance is triggered by pathogen-delivered transcription activator-like effectors (TALEs) independent of their ability to activate transcription and is suppressed by truncated variants called truncTALEs, common among Asian strains. By transformation of the susceptible variety Nipponbare, we show that one of 14 nucleotide-binding, leucine-rich repeat (NLR) protein genes at the locus, with a zinc finger BED domain, is the Xo1 gene. Analyses of published transcriptomes revealed that the Xo1-mediated response is more similar to those mediated by two other NLR resistance genes than it is to the response associated with TALE-specific transcriptional activation of the executor resistance gene Xa23 and that a truncTALE dampens or abolishes activation of defense-associated genes by Xo1. In Nicotiana benthamiana leaves, fluorescently tagged Xo1 protein, like TALEs and truncTALEs, localized to the nucleus. And endogenous Xo1 specifically coimmunoprecipitated from rice leaves with a pathogen-delivered, epitope-tagged truncTALE. These observations suggest that suppression of Xo1-function by truncTALEs occurs through direct or indirect physical interaction. They further suggest that effector coimmunoprecipitation may be effective for identifying or characterizing other resistance genes
Circulating endothelial cells are elevated in patients with type 2 diabetes mellitus independently of HbA1c
n/
Efficacy and safety of a novel delayed-release risedronate 35Â mg once-a-week tablet
Dosing regimens of oral bisphosphonates are inconvenient and contribute to poor compliance. The bone mineral density response to a once weekly delayed-release formulation of risedronate given before or following breakfast was non-inferior to traditional immediate-release risedronate given daily before breakfast. Delayed-release risedronate is a convenient regimen for oral bisphosphonate therapy
- …