1,435 research outputs found

    Computerized system for translating a torch head

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    The system provides a constant travel speed along a contoured workpiece. It has a driven skate characterized by an elongated bed, with a pair of independently pivoted trucks connected to the bed for support. The trucks are mounted on a contoured track of arbitrary configuration in a mutually spaced relation. An axially extensible torch head manipulator arm is mounted on the bed of the carriage and projects perpendicular from the midportion. The torch head is mounted at its distal end. A real-time computerized control drive subsystem is used to advance the skate along the track of a variable rate for maintaining a constant speed for the torch head tip, and to position the torch axis relative to a preset angle to the workpiece

    New two-sided bound on the isotropic Lorentz-violating parameter of modified Maxwell theory

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    There is a unique Lorentz-violating modification of the Maxwell theory of photons, which maintains gauge invariance, CPT, and renormalizability. Restricting the modified-Maxwell theory to the isotropic sector and adding a standard spin-one-half Dirac particle p^\pm with minimal coupling to the nonstandard photon \widetilde{\gamma}, the resulting modified-quantum-electrodynamics model involves a single dimensionless "deformation parameter," \widetilde{\kappa}_{tr}. The exact tree-level decay rates for two processes have been calculated: vacuum Cherenkov radiation p^\pm \to p^\pm \widetilde{\gamma} for the case of positive \widetilde{\kappa}_{tr} and photon decay \widetilde{\gamma} \to p^+ p^- for the case of negative \widetilde{\kappa}_{tr}. From the inferred absence of these decays for a particular high-quality ultrahigh-energy-cosmic-ray event detected at the Pierre Auger Observatory and an excess of TeV gamma-ray events observed by the High Energy Stereoscopic System telescopes, a two-sided bound on \widetilde{\kappa}_{tr} is obtained, which improves by eight orders of magnitude upon the best direct laboratory bound. The implications of this result are briefly discussed.Comment: 18 pages, v5: published version in preprint styl

    Improved test of Lorentz Invariance in Electrodynamics using Rotating Cryogenic Sapphire Oscillators

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    We present new results from our test of Lorentz invariance, which compares two orthogonal cryogenic sapphire microwave oscillators rotating in the lab. We have now acquired over 1 year of data, allowing us to avoid the short data set approximation (less than 1 year) that assumes no cancelation occurs between the κ~e\tilde{\kappa}_{e-} and κ~o+\tilde{\kappa}_{o+} parameters from the photon sector of the standard model extension. Thus, we are able to place independent limits on all eight κ~e\tilde{\kappa}_{e-} and κ~o+\tilde{\kappa}_{o+} parameters. Our results represents up to a factor of 10 improvement over previous non rotating measurements (which independently constrained 7 parameters), and is a slight improvement (except for κ~eZZ\tilde{\kappa}_{e-}^{ZZ}) over results from previous rotating experiments that assumed the short data set approximation. Also, an analysis in the Robertson-Mansouri-Sexl framework allows us to place a new limit on the isotropy parameter PMM=δβ+1/2P_{MM}=\delta-\beta+{1/2} of 9.4(8.1)×10119.4(8.1)\times10^{-11}, an improvement of a factor of 2.Comment: Accepted for publication in Phys. Rev.

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    Physiotherapy intervention in Parkinson's disease: systematic review and meta-analysis

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    Objective To assess the effectiveness of physiotherapy compared with no intervention in patients with Parkinson’s disease. Design Systematic review and meta-analysis of randomised controlled trials. Data sources Literature databases, trial registries, journals, abstract books, and conference proceedings, and reference lists, searched up to the end of January 2012. Review methods Randomised controlled trials comparing physiotherapy with no intervention in patients with Parkinson’s disease were eligible. Two authors independently abstracted data from each trial. Standard meta-analysis methods were used to assess the effectiveness of physiotherapy compared with no intervention. Tests for heterogeneity were used to assess for differences in treatment effect across different physiotherapy interventions used. Outcome measures were gait, functional mobility and balance, falls, clinician rated impairment and disability measures, patient rated quality of life, adverse events, compliance, and economic analysis outcomes. Results 39 trials of 1827 participants met the inclusion criteria, of which 29 trials provided data for the meta-analyses. Significant benefit from physiotherapy was reported for nine of 18 outcomes assessed. Outcomes which may be clinically significant were speed (0.04 m/s, 95% confidence interval 0.02 to 0.06, P<0.001), Berg balance scale (3.71 points, 2.30 to 5.11, P<0.001), and scores on the unified Parkinson’s disease rating scale (total score −6.15 points, −8.57 to −3.73, P<0.001; activities of daily living subscore −1.36, −2.41 to −0.30, P=0.01; motor subscore −5.01, −6.30 to −3.72, P<0.001). Indirect comparisons of the different physiotherapy interventions found no evidence that the treatment effect differed across the interventions for any outcomes assessed, apart from motor subscores on the unified Parkinson’s disease rating scale (in which one trial was found to be the cause of the heterogeneity). Conclusions Physiotherapy has short term benefits in Parkinson’s disease. A wide range of physiotherapy techniques are currently used to treat Parkinson’s disease, with little difference in treatment effects. Large, well designed, randomised controlled trials with improved methodology and reporting are needed to assess the efficacy and cost effectiveness of physiotherapy for treating Parkinson’s disease in the longer term

    Treatment technology for leachate from faecal sludge drying beds

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    The use of planted drying beds for faecal sludge treatment is effective for solid-liquid separation, but the leachate produced requires further treatment prior to discharge or reuse. This study investigates the potential of a new and low-cost solution for leachate treatment

    Test of Lorentz Invariance in Electrodynamics Using Rotating Cryogenic Sapphire Microwave Oscillators

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    We present the first results from a rotating Michelson-Morley experiment that uses two orthogonally orientated cryogenic sapphire resonator-oscillators operating in whispering gallery modes near 10 GHz. The experiment is used to test for violations of Lorentz Invariance in the frame-work of the photon sector of the Standard Model Extension (SME), as well as the isotropy term of the Robertson-Mansouri-Sexl (RMS) framework. In the SME we set a new bound on the previously unmeasured κ~eZZ\tilde{\kappa}_{e-}^{ZZ} component of 2.1(5.7)×10142.1(5.7)\times10^{-14}, and set more stringent bounds by up to a factor of 7 on seven other components. In the RMS a more stringent bound of 0.9(2.0)×1010-0.9(2.0)\times 10^{-10} on the isotropy parameter, PMM=δβ+1/2P_{MM}=\delta - \beta + {1/2} is set, which is more than a factor of 7 improvement. More detailed description of the experiment and calculations can be found in: hep-ph/0506200Comment: Final published version, 4 pages, references adde

    Mechanical strain induces growth of vascular smooth muscle cells via autocrine action of PDGF.

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    Abstract. The effect of cyclic mechanical strain on growth of neonatal rat vascular smooth muscle (VSM) cells were examined. Cells were grown on silicone elastomer plates subjected to cyclic strain (60 cycle/ min) by application of a vacuum under the plates. A 48 h exposure to mechanical strain increased the basal rate of thymidine incorporation by threefold and increased cell number by 40 % compared with cells grown on stationary rubber plates. Strain also increased the rate of thymidine incorporation in response to ot-thrombin (from 15- to 33-fold), but not to PDGE As determined by thymidine autoradiography, strain alone induced a fourfold increase in labeled nuclei at the periphery of dishes, where strain is maximal, and a 2-3-fold increase at the center of dishes

    Construction and Calibration of Optically Efficient LCD-based Multi-Layer Light Field Displays

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    Near-term commercial multi-view displays currently employ ray-based 3D or 4D light field techniques. Conventional approaches to ray-based display typically include lens arrays or heuristic barrier patterns combined with integral interlaced views on a display screen such as an LCD panel. Recent work has placed an emphasis on the co-design of optics and image formation algorithms to achieve increased frame rates, brighter images, and wider fields-of-view using optimization-in-the-loop and novel arrangements of commodity LCD panels. In this paper we examine the construction and calibration methods of computational, multi-layer LCD light field displays. We present several experimental configurations that are simple to build and can be tuned to sufficient precision to achieve a research quality light field display. We also present an analysis of moiré interference in these displays, and guidelines for diffuser placement and display alignment to reduce the effects of moiré. We describe a technique using the moiré magnifier to fine-tune the alignment of the LCD layers
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