Soft network composite materials with deterministic and bio-inspired designs

Hard and soft structural composites found in biology provide inspiration for the design of advanced synthetic materials. Many examples of bio-inspired hard materials can be found in the literature; far less attention has been devoted to soft systems. Here we introduce deterministic routes to low-modulus thin film materials with stress/strain responses that can be tailored precisely to match the non-linear properties of biological tissues, with application opportunities that range from soft biomedical devices to constructs for tissue engineering. The approach combines a low-modulus matrix with an open, stretchable network as a structural reinforcement that can yield classes of composites with a wide range of desired mechanical responses, including anisotropic, spatially heterogeneous, hierarchical and self-similar designs. Demonstrative application examples in thin, skin-mounted electrophysiological sensors with mechanics precisely matched to the human epidermis and in soft, hydrogel-based vehicles for triggered drug release suggest their broad potential uses in biomedical devices. © 2015 Macmillan Publishers Limited. All rights reservedopen7

Fallacious convergence? Williamson’s real wage comparisons under scrutiny

The idea of manifest real-wage convergence for unskilled workers in the latter half of the nineteenth century stems from an article from 1995 by Jeffrey G. Williamson. That article presented real wage comparisons of unskilled urban workers for seventeen countries. Sweden, along with the rest of Scandinavia, is found to be an influential case in accounting for much of the alleged factor price convergence taking place. This paper takes a closer look at all the three steps that have to be taken in order to establish real wage comparisons, focusing on Sweden in relation to the US and the UK. The most important findings are twofold. First, that the US–Sweden wage gap is considerably smaller for manufacturing than for building workers, and second, that the rate at which Sweden’s real wages approached the American and the British has been grossly overestimated. Swedish real wages did grow rapidly, but not as rapidly as Williamson’s comparison will have us to believe, because his real wage series does not constitute a representative account of the Swedish unskilled real wage experience. It is argued that, as we suffer from a serious paucity of data for narrow and comparable samples of late nineteenth century unskilled workers, resorting to more encompassing wage measures is a more viable option. That also implies a questioning of the American unskilled wage series, which makes considerably slower progress than the wage series for manufacturing workers.Convergence, Real wages, Wage benchmark, Purchasing power parity, Catching up, International comparisons