Getting the balance right: qualitative evaluation of a holistic weight management intervention to address childhood obesity

Background Childhood obesity is linked to a range of health and social problems. Solutions include the delivery of appropriate weight management interventions for those aged 16 and under. The ‘Balance It! Getting the Balance Right’ programme appears to be effective for those who complete the intervention, but the non-completion rate remains high. A qualitative evaluation was undertaken to explore the views of key stakeholders in the programme and identify possible reasons for non-completion. Methods Semi-structured interviews were conducted with a purposive sample of 16 NHS and local authority staff, and with 20 children (aged 4–16 years) and their families. A mosaic methodology was used, involving visual and verbal techniques employed to enable children of all ages to take an active role in expressing their opinions. Results Key themes included the challenges of approaching overweight children; positive outcomes for some families; and issues relating to communication and coordination. Participants spoke positively about the multi-disciplinary approach of ‘Balance It!’, but felt it could better meet the needs of its target population. Conclusions Structured interventions help to ensure consistency and coherence in terms of approaches to childhood overweight and obesity. Whole family approaches may be most effective in enhancing the user experience

Novel Dynamical Resonances in Finite-Temperature Bose-Einstein Condensates

We describe a variety of intriguing mode-coupling effects which can occur in a confined Bose-Einstein condensed system at finite temperature. These arise from strong interactions between a condensate fluctuation and resonances of the thermal cloud yielding strongly non-linear behaviour. We show how these processes can be affected by altering the aspect ratio of the trap, thereby changing the relevant mode-matching conditions. We illustrate how direct driving of the thermal cloud can lead to significant shifts in the excitation spectrum for a number of modes and provide further experimental scenarios in which the dramatic behaviour observed for the $m=0$ mode at JILA (Jin {\it et al.} 1997) can be repeated. Our theoretical description is based on a successful second-order finite-temperature quantum field theory which includes the full coupled dynamics of the condensate and thermal cloud and all relevant finite-size effects

Modeling laser wakefield accelerators in a Lorentz boosted frame

Modeling of laser-plasma wakefield accelerators in an optimal frame of reference \cite{VayPRL07} is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high-frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing the frame of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively

Speeding up simulations of relativistic systems using an optimal boosted frame

It can be computationally advantageous to perform computer simulations in a Lorentz boosted frame for a certain class of systems. However, even if the computer model relies on a covariant set of equations, it has been pointed out that algorithmic difficulties related to discretization errors may have to be overcome in order to take full advantage of the potential speedup. We summarize the findings, the difficulties and their solutions, and show that the technique enables simulations important to several areas of accelerator physics that are otherwise problematic, including self-consistent modeling in three-dimensions of laser wakefield accelerator stages at energies of 10 GeV and above.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072

Effects of Hyperbolic Rotation in Minkowski Space on the Modeling of Plasma Accelerators in a Lorentz Boosted Frame

Laser driven plasma accelerators promise much shorter particle accelerators but their development requires detailed simulations that challenge or exceed current capabilities. We report the first direct simulations of stages up to 1 TeV from simulations using a Lorentz boosted calculation frame resulting in a million times speedup, thanks to a frame boost as high as gamma=1300. Effects of the hyperbolic rotation in Minkowski space resulting from the frame boost on the laser propagation in the plasma is shown to be key in the mitigation of a numerical instability that was limiting previous attempts

Bulletin No. 321 - Utah Housing in Its Group and Community Aspects

The method employed in this study is to select a comparatively important segment of living--housing--for careful appraisement with the purpose of comparing different groups and localities with respect to it. Comparisons are made (1) between Utah and other states, (2) between counties of Utah, and (3) between four Utah communities. The data include the house, home conveniences, the automobile, the streets ad joining the house, newspapers, magazines, books, and connection with water, sewer, power and telephone lines. The segment is thus not small. The groups are segregated by the vocation, farm and nonfarm, from which the living is made. The communities consist of four northern Utah villages each of a different type. The purpose of the inquiry is to find out how successful the different vocational groups living in different types of. communities have been over the years in providing satisfactory homes for their families. This study, therefore, constitutes an appraisement of housing conditions that exist among the chief rural farm and nonfarm groups in the communities studied

How Much Vertical Integration? Contractual Choice and Public–Private Partnerships in the United States

Efficiency gains in public–private partnerships (PPP) derive from risk transfer and the bundling of different tasks. We study the factors that explain bundling in single contracts. We focus on the choice between integrating operational tasks alone or construction tasks alone, versus vertically integrating both operational and construction tasks. We analyze a new data set that includes 553 PPPs that were concluded in the United States. We find evidence that some financial variables play a role in bundling decisions. In addition, market size and the type of economic sectors involved, are also important drivers of contract choice and bundling decisions

Bistability in a simple fluid network due to viscosity contrast

We study the existence of multiple equilibrium states in a simple fluid network using Newtonian fluids and laminar flow. We demonstrate theoretically the presence of hysteresis and bistability, and we confirm these predictions in an experiment using two miscible fluids of different viscosity--sucrose solution and water. Possible applications include bloodflow, microfluidics, and other network flows governed by similar principles