83,653 research outputs found

    Silver-base ternary alloy proves superior for slip ring lead wires

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    Slip ring lead wires composed of ternary alloys of silver, have high electrical conductivity, a tensile strength of at least 30,000 psi, high ductility, and are solderable and weldable. An unexpected advantage of these alloys is their resistance to discoloration on heating in air

    Towards developing understanding of the drivers, constraints from the consumption values underpinning participation in physical activity.

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    Overall participation rates in physical activity across the UK have remained relatively static since the mid 1980s, with attendant causes for concern about the inequality of participation rates amongst various target groups that may be worthy of specific investigation. Behaviour change models from the fields of leisure studies, consumer behaviour and social psychology offer conceptualisation of a notion of exchange underpinning the expectancy-value process, noting that, in order to facilitate a voluntary exchange there needs to be a value proposition that induces action and/or motivates effort from the consumer. It is therefore reasonable to assume that such value expectations will also influence health behaviour intentions. This paper therefore aims to offer a more developing understanding of the drivers, constraints and experiential consumption values underpinning participation in physical activity. Results suggest that, rather than focusing on the social and altruistic values of behavioural changes, and given that the functional value of participation is already well-known (if not always acted upon) through social marketing campaigns’ educational efforts and through the media, it may be worth policymakers and leisure service providers focusing more on highlighting the emotional benefits to be gained, especially when targeting women to increase their participation in physical activit

    Why don’t people do what’s good for them? : an examination of the value(s) which affect physical activity.

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    One of the 21st Century’s major public health issues is physical inactivity. Therefore one of the greatest public policy challenges is to find new ways of conferring to an inactive population the health related benefits that arise from being physically active in a way that not only leads to knowledge acquisition, but which also leads to increased levels of participation in physical activity. Participation rates in physical activity across the UK have remained stubbornly static since the mid‐ 1980s and retain a range of gender, age, social‐economic and ethnic participation inequalities. Research has indicated that, when compared to men, women are more likely to: lead sedentary lifestyles (Hausenblas and Symons‐Downs, 2005), experience poor health (Bertakis et al., 2000), and feel more uncomfortable about their body image (Liechty et al., 2006), factors which impact on and/or result in lower participation levels, suggesting that social marketing campaigns to date have been largely ineffective. A central tenet of social marketing is to achieve a voluntary, not forced or coerced behaviour change by emphasising a value proposition that induces action from the consumer. Set in the context of publicly funded leisure facilities this paper offers empirical insights regarding the drivers, constraints and consumption values underpinning women’s participation in physical activity. Our results suggest that value perceptions regarding the costs, benefits and enjoyment of exercise do not differ with gender. However, statistically significant differences exist between the genders regarding: the physical environment within which exercise occurs; the quality of service experience; and intrinsic factors such as social and altruistic value. Insights gained from this research may be able to inform policymakers and leisure services providers regarding more effective methods of engaging ‘hard‐to‐reach’ groups, such as women. Specifically, our findings suggest that exercise adoption is likely to be increased with targeted social marketing campaigns which focus on emphasising the experiential aspects of consuming physical activity viewed from the perspective of value‐in‐use rather than from the traditional price‐based perspective that tends to focus on the trade off of costs against benefits

    Ultrasonic nondestructive evaluation of impact-damaged graphite fiber composite

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    Unidirectional Hercules AS/3501-6 graphite fiber epoxy composites were subjected to repeated controlled low-velocity drop weight impacts in the laminate direction. The degradation was ultrasonically monitored using through-thickness attenuation and a modified stress wave factor (SWF). There appears to be strong correlations between the number of drop-weight impacts, the residual tensile strength, the through-thickness attenuation, and the SWF. The results are very encouraging with respect to the NDE potential of both of these ultrasonic parameters to provide strength characterizations in virgin as well as impact-damaged fiber composite structures

    State space collapse and diffusion approximation for a network operating under a fair bandwidth sharing policy

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    We consider a connection-level model of Internet congestion control, introduced by Massouli\'{e} and Roberts [Telecommunication Systems 15 (2000) 185--201], that represents the randomly varying number of flows present in a network. Here, bandwidth is shared fairly among elastic document transfers according to a weighted α\alpha-fair bandwidth sharing policy introduced by Mo and Walrand [IEEE/ACM Transactions on Networking 8 (2000) 556--567] [α∈(0,∞)\alpha\in (0,\infty)]. Assuming Poisson arrivals and exponentially distributed document sizes, we focus on the heavy traffic regime in which the average load placed on each resource is approximately equal to its capacity. A fluid model (or functional law of large numbers approximation) for this stochastic model was derived and analyzed in a prior work [Ann. Appl. Probab. 14 (2004) 1055--1083] by two of the authors. Here, we use the long-time behavior of the solutions of the fluid model established in that paper to derive a property called multiplicative state space collapse, which, loosely speaking, shows that in diffusion scale, the flow count process for the stochastic model can be approximately recovered as a continuous lifting of the workload process.Comment: Published in at http://dx.doi.org/10.1214/08-AAP591 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Magnetocaloric effect in Gd/W thin film heterostructures

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    In an effort to understand the impact of nanostructuring on the magnetocaloric effect, we have grown and studied gadolinium in MgO/W(50 A˚\textrm{\AA})/[Gd(400 A˚\textrm{\AA})/W(50 A˚\textrm{\AA})]8_8 heterostructures. The entropy change associated with the second order magnetic phase transition was determined from the isothermal magnetization for numerous temperatures and the appropriate Maxwell relation. The entropy change peaks at a temperature of 284 K with a value of approximately 3.4 J/kg-K for a 0-30 kOe field change; the full width at half max of the entropy change peak is about 70 K, which is significantly wider than that of bulk Gd under similar conditions. The relative cooling power of this nanoscale system is about 240 J/kg, somewhat lower than that of bulk Gd (410 J/kg). An iterative Kovel-Fisher method was used to determine the critical exponents governing the phase transition to be ÎČ=0.51\beta=0.51, and Îł=1.75\gamma=1.75. Along with a suppressed Curie temperature relative to the bulk, the fact that the convergent value of Îł\gamma is that predicted by the 2-D Ising model may suggest that finite size effects play an important role in this system. Together, these observations suggest that nanostructuring may be a promising route to tailoring the magnetocaloric response of materials

    Investigation, Testing, and Selection of Slip-ring Lead Wires for Use in High-precision Slip-ring Capsules Final Report

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    Evaluation of corrosion resistant silver alloys for use in lead wires for slip-ring assemblies of Saturn guidance and control system

    Future monitoring of charged particle energy deposition into the upper atmosphere and comments on possible relationships between atmospheric phenomena and solar and/or geomagnetic activity

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    Monitoring of earth's atmosphere was conducted for several years utilizing the ITOS series of low-altitude, polar-orbiting weather satellites. A space environment monitoring package was included in these satellites to perform measurements of a portion of earth's charged particle environment. The charged particle observations proposed for the low-altitude weather satellite TIROS N, are described which will provide the capability of routine monitoring of the instantaneous total energy deposition into the upper atmosphere by the precipitation of charged particles from higher altitudes. Such observations may be of use in future studies of the relationships between geomagnetic activity and atmospheric weather pattern developments. Estimates are given to assess the potential importance of this type of energy deposition. Discussion and examples are presented illustrating the importance of distinguishing between solar and geomagnetic activity as possible causative sources. Such differentiation is necessary because of the widely different spatial and time scales involved in the atmospheric energy input resulting from these various sources of activity

    The health state preferences and logistical inconsistencies of New Zealanders: a tale of two tariffs

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    Notwithstanding the proposed use of Cost-Utility Analysis (CUA) to inform health care priority setting in New Zealand, to date there has been no research into New Zealanders’ valuations of health-related quality of life. This paper reports the results of a study of the health state preferences of adult New Zealanders generated from a postal survey to which 1360 people responded (a 50% response rate). The survey employed a self-completed questionnaire in which a selection of health states were described using the EQ-5D health state classification system and respondents’ valuations were sought using a visual analogue scale (VAS). Close attention is paid to the quality of the data, in particular to the ‘logical inconsistencies’ in respondents’ valuations. Regression analysis is used to interpolate values over the 245 possible EQ-5D states. Two tariffs of health state preferences, arising from contrasting treatments of the logical inconsistencies, are reported.New Zealand, EuroQol, EQ-5D

    Start-to-end modelling of a mode-locked optical klystron free electron laser amplifier

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    A free electron laser (FEL) in a mode-locked optical klystron (MLOK) configuration is modelled using start-to-end simulations that simulate realistic electron beam acceleration and transport before input into a full three-dimensional FEL simulation code. These simulations demonstrate that the MLOK scheme is compatible with the present generation of radiofrequency accelerator designs. A train of few-optical cycle pulses is predicted with peak powers similar to those of the equivalent conventional FEL amplifier. The role of electron beam energy modulation in these results is explained and the limitations of some simulation codes discussed. It is shown how seeding the FEL interaction using a High Harmonic seed laser can improve the coherence properties of the output
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