945 research outputs found

    Design of an advanced 500-hp helicopter transmission

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    High contact ratio spar gears planetary, spiral besel gears, bearings, investment-cast planet carrier, and investment cast stainless-steel housings are discussed

    Historical Art, Ecology, and Implication

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    For fifteen years, I have researched, published, lectured, and taught about art and ecology, focusing on contemporary contexts as well as historical work produced long before Ernst Haeckel coined “ecology” (Oecologie) in 1866, and prior to the emergence of modern environmentalism..

    Reentry static stability characteristics of a (Model 471) .005479-scale 146-inch solid rocket booster tested in the NASA/MSFC 14 by 14 inch TWT (SA8F)

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    A force test of a scale model of the Space Shuttle Solid Rocket Booster was conducted in a trisonic wind tunnel. The model was tested with such protuberances as a camera capsule, electrical tunnel, attach rings, aft separation rockets, ET attachment structure, and hold-down struts. The model was also tested with the nozzle at gimbal angles of 0, 2.5, and 5 degrees. The influence of a unique heat shield configuration was also determined. Some photographs of model installations in the tunnel were taken and are included. Schlieren photography was utilized for several angles of attack

    Using a finite element grid on corner points in flow models

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    One of the main functions of a multilayer cover liner is to prevent water from infiltrating into mine or other waste thereby preventing the occurrence of ground water pollution. In the past, numerical models have predominantly dealt with vertical infiltration or infiltration into sloping hillsides of infinite extent. The two layer model investigated in this paper has a more realistic shape which is piece-wise linear with a horizontal top, vertical bottom and a sloping section in-between. At the intersection of these segments are corner points where there are changes from sloping flow dynamics to either vertical or horizontal flow dynamics, depending on the corner point. The abrupt change in dynamics at the corner points can cause numerical problems especially when dealing with the boundary condition at the interface of two soils. This paper will deal with the corner point problem at the soil layer interface and, in particular, investigate the use of a finite element grid around the corner points

    Mechanistic studies on the copper-catalyzed N-arylation of alkylamines promoted by organic soluble ionic bases

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    Experimental studies on the mechanism of copper-catalyzed amination of aryl halides have been undertaken for the coupling of piperidine with iodobenzene using a Cu­(I) catalyst and the organic base tetrabutylphosphonium malonate (TBPM). The use of TBPM led to high reactivity and high conversion rates in the coupling reaction, as well as obviating any mass transfer effects. The often commonly employed O,O-chelating ligand 2-acetylcyclohexanone was surprisingly found to have a negligible effect on the reaction rate, and on the basis of NMR, calorimetric, and kinetic modeling studies, the malonate dianion in TBPM is instead postulated to act as an ancillary ligand in this system. Kinetic profiling using reaction progress kinetic analysis (RPKA) methods show the reaction rate to have a dependence on all of the reaction components in the concentration range studied, with first-order kinetics with respect to [amine], [aryl halide], and [Cu]<sub>total</sub>. Unexpectedly, negative first-order kinetics in [TBPM] was observed. This negative rate dependence in [TBPM] can be explained by the formation of an off-cycle copper­(I) dimalonate species, which is also argued to undergo disproportionation and is thus responsible for catalyst deactivation. The key role of the amine in minimizing catalyst deactivation is also highlighted by the kinetic studies. An examination of the aryl halide activation mechanism using radical probes was undertaken, which is consistent with an oxidative addition pathway. On the basis of these findings, a more detailed mechanistic cycle for the C–N coupling is proposed, including catalyst deactivation pathways

    Deconstructing patient centred communication and uncovering shared decision making: an observational study

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    BACKGROUND: Patient centred communication (PCC) has been described as a method for doctor-patient communication. The principles of shared decision making (SDM) have been proposed more recently. AIMS: This study aimed to examine PCC and SDM empirically with respect to their mutual association, the variation in practitioners' working styles, and the associations with patient characteristics. METHODS: Sixty general practitioners recruited 596 adult patients who gave written consent to have their consultations videotaped. The tapes were assessed by two researchers, using a standardised instrument for global communication. For the purpose of this exploratory study, scales for PCC and SDM were based on subsamples of items in the MAAS. RESULTS: The scales for PCC and SDM were weakly associated (Pearson correlation: 0.25). Physicians varied more on SDM than on PCC. The intracluster correlation of the PCC and SDM scales were, respectively, 0.34 and 0.19. However, hypotheses regarding associations with patient characteristics were not confirmed. Neither PCC nor SDM scores were related to patient gender, education, age, functional health status or existence of chronic conditions. CONCLUSION: The study provides evidence that PCC and SDM can be differentiated and comprise approaches to communication between clinicians and patients which may be more clearly distinguished by further focused research and training developments

    Arduous implementation: Does the Normalisation Process Model explain why it's so difficult to embed decision support technologies for patients in routine clinical practice

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    Background: decision support technologies (DSTs, also known as decision aids) help patients and professionals take part in collaborative decision-making processes. Trials have shown favorable impacts on patient knowledge, satisfaction, decisional conflict and confidence. However, they have not become routinely embedded in health care settings. Few studies have approached this issue using a theoretical framework. We explained problems of implementing DSTs using the Normalization Process Model, a conceptual model that focuses attention on how complex interventions become routinely embedded in practice.Methods: the Normalization Process Model was used as the basis of conceptual analysis of the outcomes of previous primary research and reviews. Using a virtual working environment we applied the model and its main concepts to examine: the 'workability' of DSTs in professional-patient interactions; how DSTs affect knowledge relations between their users; how DSTs impact on users' skills and performance; and the impact of DSTs on the allocation of organizational resources.Results: conceptual analysis using the Normalization Process Model provided insight on implementation problems for DSTs in routine settings. Current research focuses mainly on the interactional workability of these technologies, but factors related to divisions of labor and health care, and the organizational contexts in which DSTs are used, are poorly described and understood.Conclusion: the model successfully provided a framework for helping to identify factors that promote and inhibit the implementation of DSTs in healthcare and gave us insights into factors influencing the introduction of new technologies into contexts where negotiations are characterized by asymmetries of power and knowledge. Future research and development on the deployment of DSTs needs to take a more holistic approach and give emphasis to the structural conditions and social norms in which these technologies are enacte

    Communication style and exercise compliance in physiotherapy (CONNECT). A cluster randomized controlled trial to test a theory-based intervention to increase chronic low back pain patients’ adherence to physiotherapists’ recommendations: study rationale, design, and methods

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    Physical activity and exercise therapy are among the accepted clinical rehabilitation guidelines and are recommended self-management strategies for chronic low back pain. However, many back pain sufferers do not adhere to their physiotherapist’s recommendations. Poor patient adherence may decrease the effectiveness of advice and home-based rehabilitation exercises. According to self-determination theory, support from health care practitioners can promote patients’ autonomous motivation and greater long-term behavioral persistence (e.g., adherence to physiotherapists’ recommendations). The aim of this trial is to assess the effect of an intervention designed to increase physiotherapists’ autonomy-supportive communication on low back pain patients’ adherence to physical activity and exercise therapy recommendations. \ud \ud This study will be a single-blinded cluster randomized controlled trial. Outpatient physiotherapy centers (N =12) in Dublin, Ireland (population = 1.25 million) will be randomly assigned using a computer-generated algorithm to either the experimental or control arm. Physiotherapists in the experimental arm (two hospitals and four primary care clinics) will attend eight hours of communication skills training. Training will include handouts, workbooks, video examples, role-play, and discussion designed to teach physiotherapists how to communicate in a manner that promotes autonomous patient motivation. Physiotherapists in the waitlist control arm (two hospitals and four primary care clinics) will not receive this training. Participants (N = 292) with chronic low back pain will complete assessments at baseline, as well as 1 week, 4 weeks, 12 weeks, and 24 weeks after their first physiotherapy appointment. Primary outcomes will include adherence to physiotherapy recommendations, as well as low back pain, function, and well-being. Participants will be blinded to treatment allocation, as they will not be told if their physiotherapist has received the communication skills training. Outcome assessors will also be blinded. \ud \ud We will use linear mixed modeling to test between arm differences both in the mean levels and the rates of change of the outcome variables. We will employ structural equation modeling to examine the process of change, including hypothesized mediation effects. \ud \ud This trial will be the first to test the effect of a self-determination theory-based communication skills training program for physiotherapists on their low back pain patients’ adherence to rehabilitation recommendations. Current Controlled Trials ISRCTN63723433\u

    The Roulette Wheel: An Aid to Informed Decision Making

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    The authors outline a new visual tool that can help patients assess the benefits and risks of different treatments
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