Narrative, Sensemaking, and Improvisation in Participatory Hypermedia Construction

In this paper we describe research into a form of practitioner sensemaking in the context of participatory hypermedia construction sessions, in which groups of people build knowledge maps. We discuss how constructs from narrative theory and improvisation have helped us understand what happens at the moments when practitioners encounter dilemmas and obstacles. We provide brief examples from case studies and discuss possible contributions to broader themes in sensemaking research

A new chiral electro-optic effect: Sum-frequency generation from optically active liquids in the presence of a dc electric field

We report the observation of sum-frequency signals that depend linearly on an applied electrostatic field and that change sign with the handedness of an optically active solution. This recently predicted chiral electro-optic effect exists in the electric-dipole approximation. The static electric field gives rise to an electric-field-induced sum-frequency signal (an achiral third-order process) that interferes with the chirality-specific sum-frequency at second-order. The cross-terms linear in the electrostatic field constitute the effect and may be used to determine the absolute sign of second- and third-order nonlinear optical susceptibilities in isotropic media.Comment: Submitted to Physical Revie

Coupled convective and radiative heating to superorbital entry vehicles

Coupled convective and radiative heating of suborbital entry vehicle

A uniform Time Trade Off method for states better and worse than dead: feasibility study of the ‘lead time’ approach

The way Time Trade Off (TTO) values are elicited for states of health considered ‘worse than being dead’ has important implications for the mean values used in economic evaluation. Conventional approaches to TTO, as used in the UK’s ‘MVH’ value set, are problematic because they require fundamentally different tradeoffs tasks for the valuation of states better and worse than dead. This study aims to refine and test the feasibility of a new approach described by Robinson and Spencer (2006), and to explore the characteristics of the valuation data it generates. The approach introduces a ‘lead time’ into the TTO, producing a uniform procedure for generating values either >0 or <0. We used this lead time TTO to value 10 moderate to severe EQ-5D states using a sample of the general public (n=109). We conclude that the approach is feasible for use in valuation studies, and appears to overcome the discontinuity in values around 0 evident in conventional methods. However, further research is required to resolve the issue of how to handle participants who ‘use up’ all lead time; to develop ways of controlling for individual time preferences; and to better understand the implications for valuations of states better than dead

Does the value of quality of life depend on duration?

The aims of this study are to investigate the feasibility of eliciting Time Trade Off (TTO) valuations using short durations; to determine the effect of contrasting durations on individuals’ responses to the TTO; to examine variations within and between respondents’ values with respect to duration; and to consider the insights provided by participants’ comments and explanations regarding their reaction to duration in the valuation task. 27 participants provided TTO values using short and long durations for three EQ-5D states. Feedback was sought using a series of open ended questions. Of the 81 opportunities to observe it, strict constant proportionality was satisfied twice. 11 participants had no systematic relationship between duration and value; 11 provided consistently lower valuations in long durations, while 5 had higher valuations in long durations. Comments provided by participants were consistent with the values they provided. Mean TTO values did not differ markedly between alternative durations. We conclude that it is feasible to elicit TTO values for short durations. There is considerable heterogeneity in individuals’ responses to the time frames used to elicit values. Further research is required to ensure that the values used in cost effectiveness analysis adequately represent preferences about quality and length of life

Dimensional analysis using toric ideals: Primitive invariants

© 2014 Atherton et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Classical dimensional analysis in its original form starts by expressing the units for derived quantities, such as force, in terms of power products of basic units M, L, T etc. This suggests the use of toric ideal theory from algebraic geometry. Within this the Graver basis provides a unique primitive basis in a well-defined sense, which typically has more terms than the standard Buckingham approach. Some textbook examples are revisited and the full set of primitive invariants found. First, a worked example based on convection is introduced to recall the Buckingham method, but using computer algebra to obtain an integer K matrix from the initial integer A matrix holding the exponents for the derived quantities. The K matrix defines the dimensionless variables. But, rather than this integer linear algebra approach it is shown how, by staying with the power product representation, the full set of invariants (dimensionless groups) is obtained directly from the toric ideal defined by A. One candidate for the set of invariants is a simple basis of the toric ideal. This, although larger than the rank of K, is typically not unique. However, the alternative Graver basis is unique and defines a maximal set of invariants, which are primitive in a simple sense. In addition to the running example four examples are taken from: a windmill, convection, electrodynamics and the hydrogen atom. The method reveals some named invariants. A selection of computer algebra packages is used to show the considerable ease with which both a simple basis and a Graver basis can be found.The third author received funding from Leverhulme Trust Emeritus Fellowship (1-SST-U445) and United Kingdom EPSRC grant: MUCM EP/D049993/1

Is Cardiovascular Health Affected by Exercise Type and Impact?

The principal aim of this study was to determine whether cardiovascular health, assessed by resting systolic and diastolic blood pressure and resting heart rate, was affected by exercise type (golf vs. tennis) and associated impact (low vs. high). Male and female golfers (n = 40) and tennis players (n = 40) aged between 40 and 71 years completed a short questionnaire relating to their main sport and typical exercise habits. Resting blood pressure and heart rate readings were then taken using an electronic wrist sphygmomanometer. The analysis of variance (General Linear Model) showed that overall there were no significant differences in either the resting systolic or diastolic blood pressure, or resting heart rate, of golfers and tennis players. However, a significant increase in systolic blood pressure with age (F = 10.48, p = 0.002) was observed in golfers, compared with no significant age-related increases in blood pressure in tennis players. In conclusion, exercise type and impact appear to have no effect on cardiovascular health in the 40 to 71 year olds age group, but high impact exercise may have a protective effect against age-related increases in blood pressure which requires further investigation

Quantum Fluctuations of a Coulomb Potential as a Source of Flicker Noise

The power spectrum of quantum fluctuations of the electromagnetic field produced by an elementary particle is determined. It is found that in a wide range of practically important frequencies the power spectrum of fluctuations exhibits an inverse frequency dependence. The magnitude of fluctuations produced by a conducting sample is shown to have a Gaussian distribution around its mean value, and its dependence on the sample geometry is determined. In particular, it is demonstrated that for geometrically similar samples the power spectrum is inversely proportional to the sample volume. It is argued also that the magnitude of fluctuations induced by external electric field is proportional to the field strength squared. A comparison with experimental data on flicker noise measurements in continuous metal films is made.Comment: 11 pages, substantially corrected and extende