Five minutes with Mark Blyth: “Turn it into things people can understand, let go of the academese, and people will engage”

Mark Blyth became the accidental star of the political blogosphere last year when he appeared in a video promoting the key message behind his upcoming book ‘Austerity: The History of a Dangerous Idea’. Here he explains why being unreadable helps economists get their message across, how fan and hate mail have become part of his professional life and how his latest project illustrates that there is a market for academic ideas

Secondary resurfacing of the patella in total knee arthroplasty

Anterior knee pain following primary total knee arthroplasty is common and can be difficult to treat satisfactorily. We reviewed 28 consecutive patients (29 knees) who underwent secondary resurfacing of the patella for persistent anterior knee pain and report on the results. Mean follow-up was 28 months (range12-61) with no cases lost to follow-up. Oxford knee scores, range of motion, the patient's assessment of outcome and overall satisfaction were recorded. Seventeen out of 19 (59%) felt their knee was better following patellar resurfacing, 10 out of 29 (34%) felt it was the same and two out of 29 (7%) felt it was worse. There was a significant improvement in Oxford knee scores (p < 0.001) and significant increase in patient satisfaction (p < 0.001) following secondary resurfacing. While secondary resurfacing of the patella does not provide the solution for every case of anterior knee pain following total knee joint replacement, in greater than 50% of cases it can be effective at relieving symptoms and in this series carries a low risk of worsening symptoms or complications

The role of soluble surfactants in the linear stability of two-layer flow in a channel

The linear stability of Couette-Poiseuille flow of two superposed fluid layers in a horizontal channel is considered. The lower fluid layer is populated with surfactants that appear either in the form of monomers or micelles and can also get adsorbed at the interface between the fluids. A mathematical model is formulated which combines the Navier- Stokes equations in each fluid layer, convection-diffusion equations for the concentration of monomers (at the interface and in the bulk fluid) and micelles (in the bulk), together with appropriate coupling conditions at the interface. The primary aim of this study is to investigate when the system is unstable to arbitrary wavelength perturbations, and in particular, to determine the influence of surfactant solubility and/or sorption kinetics on the instability. A linear stability analysis is performed and the growth rates are obtained by solving an eigenvalue problem for Stokes flow, both numerically for disturbances of arbitrary wavelength and analytically using long-wave approximations. It is found that the system is stable when the surfactant is sufficiently soluble in the bulk and if the fluid viscosity ratio m and thickness ratio n satisfy the condition m < n2. On the other hand, the effect of surfactant solubility is found to be destabilising if m n2. Both of the aforementioned results are manifested for low bulk concentrations below the critical micelle concentration; however when the equilibrium bulk concentration is sufficiently high (and above the critical micelle concentration) so that micelles are formed in the bulk fluid, the system is stable if m < n2 in all cases examined

A frame signature matrix for analysing and comparing interaction design behaviour

Protocol studies are an established method to investigate design behaviour. In the context of a project to investigate novice interaction design (ID) behaviour across protocols and cultures, we found that existing design behaviour analysis frameworks did not provide reliable results. This paper describes the development of a new approach to analyse and compare ID behaviour using verbal protocols. We augment Schön’s basic design and reflection cycle with construction of a frame signature matrix and analogical categorisation coding. We demonstrate this approach by comparing two protocols of novice interaction designers in Botswana. The initial findings indicate that this approach increases consistency and accuracy of coding, and that there are different degrees of reframing for the design problem and solutions

How water flow, geometry and material properties drive plant movements

Plants are dynamic. They adjust their shape for feeding, defence and reproduction. Such plant movements are critical for their survival. We present selected examples covering a range of movements from single cell to tissue level and over a range of timescales. We focus on reversible turgor-driven shape changes. Recent insights into the mechanisms of stomata, bladderwort, the waterwheel and the Venus flytrap are presented. The underlying physical principles (turgor, osmosis, membrane permeability, wall stress, snap buckling, elastic instability) are highlighted and advances in our understanding of these processes are summarised

Co-evolving problems and solutions: The case of novice interaction designers in Botswana and the UK

This paper establishes that problem-solution co-evolution is observed in novice interaction designers in the UK and Botswana. However, in the majority of Botswana protocols we could see a new type of co-evolution, which we termed solution-problem co-evolution. Solution- problem co-evolution uses ‘off the shelf’’ solutions to structure the problem space. Both types of co-evolution are described and discussed in this paper. The findings are drawn from the analysis of 18 (5 UK, 13 Botswana) 1-hour design protocols from two cohorts of students studying the same undergraduate Open University Interaction Design module, one in Botswana and one in the UK. Participants were required to complete a medical interaction design task under controlled conditions. We based our analysis on a coding scheme that was developed specifically for this protocol study. The coding scheme is based on Schön’s seminal work on reflective practice. It visually represents activities in the problem and solutions spaces