1,214 research outputs found

    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

    Modelling dimethylsulphide production at the Bermuda Atlantic time series (BATS)

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    Dimethylsulphide (DMS) is produced by upper ocean ecosystems and emitted to the atmosphere where it may have an important role in climate regulation. Several attempts to quantify the role of DMS in climate change have been undertaken in modeling studies. We examine a model of biogenic DMS production and describe its endogenous dynamics and sensitivities. We extend the model to develop a one-dimensional version that more accurately resolves the important processes of the mixed layer in determining the ecosystem dynamics. Comparisons of the results of the one-dimensional model with vertical profiles of DMS in the upper ocean measured at the Bermuda Atlantic Time Series suggest that the model represents the interaction between the biological and physical processes well. Our analysis of the model confirms its veracity and provides insights into the important processes determining DMS concentration in the oceans

    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

    Molecular basis of FIR-mediated c-myc transcriptional control

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    The far upstream element (FUSE) regulatory system promotes a peak in the concentration of c-Myc during cell cycle. First, the FBP transcriptional activator binds to the FUSE DNA element upstream of the c-myc promoter. Then, FBP recruits its specific repressor (FIR), which acts as an on/off transcriptional switch. Here we describe the molecular basis of FIR recruitment, showing that the tandem RNA recognition motifs of FIR provide a platform for independent FUSE DNA and FBP protein binding and explaining the structural basis of the reversibility of the FBP-FIR interaction. We also show that the physical coupling between FBP and FIR is modulated by a flexible linker positioned sequentially to the recruiting element. Our data explain how the FUSE system precisely regulates c-myc transcription and suggest that a small change in FBP-FIR affinity leads to a substantial effect on c-Myc concentration.MRC Grant-in-aid U11757455

    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

    On the elliptic generating region of a tsunami

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    The surface elevation is calculated for the three-dimensional motion of waves in a fluid of constant depth subject to a given bottom velocity. An example, modeling tsunami generation, with antisymmetric bottom velocity, is considered in detail. The amplitude of the wave front is found to decay much more rapidly than the main wave. The distribution of amplitude with wave number and with angular position is computed for some cases

    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

    Reentry aerodynamic characteristics of a space shuttle solid rocket booster (MSFC model 454) at high angles of attack and high Mach number in the NASA/Langley four-foot unitary plan wind tunnel (SA25F)

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    A force test of a 2.112 percent scale Space Shuttle Solid Rocket Booster (SRB), MSFC Model 454, was conducted in test section no. 2 of the Unitary Plan Wind Tunnel. Sixteen (16) runs (pitch polars) were performed over an angle of attack range from 144 through 179 degrees. Test Mach numbers were 2.30, 2.70, 2.96, 3.48, 4.00 and 4.63. The first three Mach numbers had a test Reynolds number of 1.5 million per foot. The remaining three were at 2.0 million per foot. The model was tested in the following configurations: (1) SRB without external protuberances, and (2) SRB with an electrical tunnel and a SRB/ET thrust attachment structure. Schlieren photographs were taken during the testing of the first configuration. The second configuration was tested at roll angles of 45, 90, and 135 degrees

    An investigation to determine the static pressure distribution of the 0.00548 scale shuttle solid rocket booster (MSFC model number 468) during reentry in the NASA/MSFC 14 inch trisonic wind tunnel (SA28F)

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    The results of a pressure test of a .00548 scale 146 inch Space Shuttle Solid Rocket Booster (SRB) with and without protuberances, conducted in a 14 x 14 inch trisonic wind tunnel are presented. Static pressure distributions for the SRB at reentry attitudes and flight conditions were obtained. Local longitudinal and ring pressure distributions are presented in tabulated form. Integration of the pressure data was performed. The test was conducted at Mach numbers of 0.40 to 4.45 over an angle of attack range from 60 to 185 degrees. Roll angles of 0, 45, 90 and 315 degrees were investigated. Reynolds numbers per foot varied for selected Mach numbers
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