3,407 research outputs found
Non-invasive Optical End-to-End Test of a Large TMA Telescope (JWST) from the Intermediate Focus
The James Webb Space Telescope (JWST) requires testing of the full optical system in a cryogenic vacuum environment before launch. Challenges with the telescope architecture and the test environment lead to placing removable optical test sources at the Cassegrain intermediate focus of the Telescope. The Science Instrument suite will be used to align the telescope and to verify the wavefront error. The Science Instruments capture test images that are analyzed using focus diverse phase retrieval. The wavefront sensing algorithms have the large dynamic range required to measure the relatively small wavefronts of interest in the presence of the large aberrations resulting from the off-axis source locations at the intermediate focus. These inherent aberrations of the off-axis design are removed analytically from the measured data. The test design and in-situ wavefront sensing process enables a number of tests to verify the alignment and optical quality of the system
A multicentre trial of voltaren in the treatment of rheumatoid arthritis
Voltaren, a compound with analgesic, anti-inflammatory and antipyretic properties, has been compared at two dose levels-25 mg t.d.s. and 50 mg t.d.s. with indomethacin 25 mg t.d.s. and acetylsalicylic acid 1 500 mg t.d.s. Ninety-one patients with definite or classical rheumatoid arthritis took part in this study. The trial was a doubleblind cross-over study, with each medication being given for one week. Patients were washed out for one week prior to the first active treatment. Each patient received only two of the four possible treatments. Voltaren in a dose of 25 mg t.d.s. was found to improve the symptoms of rheumatoid arthritis to a greater degree than indomethacin or acetylsalicylic acid. Voltaren 50 mg t.d.s. evoked a greater response than acetylsalicylic acid and was at least as efficacious as indomethacin. Voltaren was better tolerated than either indomethacin or acetylsalicylic acid. The incidence of gastro-intestinal side-effects was similar with Voltaren and indomethacin, and half that produced by acetylsalicylic acid. Some evidence of possible drug interaction was found.S. Afr. Med. J., 48, 2013 (1974)
Oral rivaroxaban versus standard therapy for the treatment of symptomatic venous thromboembolism : a pooled analysis of the EINSTEIN-DVT and PE randomized studies
Background: Standard treatment for venous thromboembolism (VTE) consists of a heparin combined with vitamin K antagonists. Direct oral anticoagulants have been investigated for acute and extended treatment of symptomatic VTE; their use could avoid parenteral treatment and/or laboratory monitoring of anticoagulant effects.
Methods: A prespecified pooled analysis of the EINSTEIN-DVT and EINSTEIN-PE studies compared the efficacy and safety of rivaroxaban (15 mg twice-daily for 21 days, followed by 20 mg once-daily) with standard-therapy (enoxaparin 1.0 mg/kg twice-daily and warfarin or acenocoumarol). Patients were treated for 3, 6, or 12 months and followed for suspected recurrent VTE and bleeding. The prespecified noninferiority margin was 1.75.
Results: 8282 patients were enrolled. 4151 received rivaroxaban and 4131 received standard-therapy. The primary efficacy outcome occurred in 86 rivaroxaban-treated patients (2.1%) compared with 95 (2.3%) standard-therapy-treated patients (hazard ratio, 0.89; 95% confidence interval [CI], 0.66-1.19; pnoninferiority<0.001). Major bleeding was observed in 40 (1.0%) and 72 (1.7%) patients in the rivaroxaban and standard-therapy groups, respectively (hazard ratio, 0.54; 95% CI, 0.37-0.79; p=0.002). In key subgroups, including fragile patients, cancer patients, patients presenting with large clots and those with a history of recurrent VTE, the efficacy and safety of rivaroxaban was similar compared with standard-therapy.
Conclusion: The single-drug approach with rivaroxaban resulted in similar efficacy to standard-therapy and was associated with a significantly lower rate of major bleeding. Efficacy and safety results were consistent among key patient subgroups
Simulation-based reachability analysis for nonlinear systems using componentwise contraction properties
A shortcoming of existing reachability approaches for nonlinear systems is
the poor scalability with the number of continuous state variables. To mitigate
this problem we present a simulation-based approach where we first sample a
number of trajectories of the system and next establish bounds on the
convergence or divergence between the samples and neighboring trajectories. We
compute these bounds using contraction theory and reduce the conservatism by
partitioning the state vector into several components and analyzing contraction
properties separately in each direction. Among other benefits this allows us to
analyze the effect of constant but uncertain parameters by treating them as
state variables and partitioning them into a separate direction. We next
present a numerical procedure to search for weighted norms that yield a
prescribed contraction rate, which can be incorporated in the reachability
algorithm to adjust the weights to minimize the growth of the reachable set
Parameterized tests of the strong-field dynamics of general relativity using gravitational wave signals from coalescing binary black holes: Fast likelihood calculations and sensitivity of the method
Thanks to the recent discoveries of gravitational wave signals from binary
black hole mergers by Advanced Laser Interferometer Gravitational Wave
Observatory and Advanced Virgo, the genuinely strong-field dynamics of
spacetime can now be probed, allowing for stringent tests of general relativity
(GR). One set of tests consists of allowing for parametrized deformations away
from GR in the template waveform models and then constraining the size of the
deviations, as was done for the detected signals in previous work. In this
paper, we construct reduced-order quadratures so as to speed up likelihood
calculations for parameter estimation on future events. Next, we explicitly
demonstrate the robustness of the parametrized tests by showing that they will
correctly indicate consistency with GR if the theory is valid. We also check to
what extent deviations from GR can be constrained as information from an
increasing number of detections is combined. Finally, we evaluate the
sensitivity of the method to possible violations of GR.Comment: 19 pages, many figures. Matches PRD versio
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P3 microengine development at Washington State University.
There is a pressing need for miniaturized power systems for a variety of applications requiring a long life in the field of operations. Such power systems are required to be capable of providing power for months to years of operation, which all but eliminates battery technologies and technologies that bring their own fuel systems (except for nuclear fuel systems, which have their own drawbacks) due to constraints of having the all of the chemical fuel necessary for the entire life of the operational run available at the starting point of the operation. Alternatively, harvesting energy directly from the local environment obviates this need for bringing along all of the fuel necessary for operation. Instead, locally available energy, either in the form of chemical, thermal, light, or motion can be harvested and converted into electrical energy for use in sensor applications. The work from this LDRD is focused on developing a thermal engine that can take scavenged thermal gradients and convert them into direct electrical energy. The converter system is a MEMS based external combustion engine that uses a modified Stirling cycle to generate mechanical work on a piezoelectric generator. This piezoelectric generator then produced an AC voltage and current that can be delivered into an external load. The MEMS engine works on the conversion of a two phase working fluid trapped between two deformable membranes. As heat is added to the system, the liquid working fluid is converted to a gas, which exerts pneumatic pressure on the membranes, expanding them outward. This outward expansion continues after the heat input is removed when the engine is operated at resonance, since the membrane is expanded further due to inertial forces. Finally, the engine cools and heat rejection is accomplished through the membranes, closing the thermodynamic cycle. A piezoelectric generator stack is deposited on one of the membranes, and this generator extracts the strain energy work from the membrane expansion and generates electrical work. The overall system is pulsed by an electrical heater to generate the input heat pulse. Currently, the system has a resonant frequency that is in the low kilohertz regime, but operations under a dynamic damping have demonstrated operation at resonance and the existence of an open mechanical cycle of heat addition, expansion, and heat rejection. Power generation of direct thermal-to-electrical conversion show a 1.45W, 6mJ heat pulse can generate a 0.8 {micro}W power output pulse, and continuous operation generates a sustained power output of 0.8 {micro}W at 240Hz. Future improvements in the device will allow active heat rejection, allowing resonance with external damping to improve the thermal to electrical power efficiency
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