Sodium ion dynamics in a sulfonate based ionomer system studied by 23Na solid-state nuclear magnetic resonance and impedance spectroscopy

A poly(2-acrylamido-2-methyl-1-propane-sulphonate) (PAMPS) ionomer containing both sodium and quaternary ammonium cations functionalised with an ether group, has been characterised in terms of its thermal properties, ionic conductivity and sodium ion dynamics. The ether oxygen was incorporated to reduce the Na+ association with the anionic sulfonate groups tethered to the polymer backbone, thereby promoting ion dissociation and ultimately enhancing the ionic conductivity. This functionalised ammonium cation led to a significant reduction in the ionomer Tg compared to an analogue system without an ether group, resulting in an increase in ionic conductivity of approximately four orders of magnitude. The sodium ion dynamics were probed by 23Na solid-state NMR, which allowed the signals from the dissociated (mobile) and bound Na+ cations to be distinguished. This demonstrates the utility of 23Na solid-state NMR as a probe of sodium dynamics in ionomer systems.

Our girth is plain to see: an analysis of newspaper coverage of Australia's future 'fat bomb'

The news media plays an important role in making visible and shaping public understandings of health and health risks. In relation to overweight and obesity, it has been suggested that the media is more likely to engage in alarmist reporting in a climate in which it is taken for granted that obesity is an 'epidemic'. This study analyses Australian media coverage of a report on overweight and obesity, Australia's Future 'Fat Bomb': a report on the long-term consequences of Australia's expanding waistline on cardiovascular disease, by one of Australia's leading health and medical research institutes. Our study found that the report was consistently framed across media outlets as showing that Australia is the 'fattest nation' in the world, having overtaken the Americans. This is despite the fact that the Fat Bomb study did not include international comparisons and was based only on data from middle-aged Australians. Because reports of increasing rates of obesity had already been widely covered in the media, the press needed to find a new way of signifying the problem, which was provided by comments made by its lead author in publicising the report. Consistent with previous research, there was a notable absence of critical commentary on the study and a failure to test the claims of its lead author. We conclude that this reporting could have contributed to a policy environment in which the perceived threat of obesity is deemed to be so great that efforts to contain it may be subjected to less scrutiny than they warrant. © 2011 Taylor & Francis.

Lingo: linearized grassmannian optimization for nuclear norm minimization

As a popular heuristic to the matrix rank minimization problem, nuclear norm minimization attracts intensive research attentions. Matrix factorization based algorithms can reduce the expensive computation cost of SVD for nuclear norm minimization. However, most matrix factorization based algorithms fail to provide the theoretical guarantee for convergence caused by their non-unique factorizations. This paper proposes an efficient and accurate Linearized Grass-mannian Optimization (Lingo) algorithm, which adopts matrix factorization and Grassmann manifold structure to alternatively minimize the subproblems. More specially, linearization strategy makes the auxiliary variables unnecessary and guarantees the close-form solution for low periteration complexity. Lingo then converts linearized objective function into a nuclear norm minimization over Grass-mannian manifold, which could remedy the non-unique of solution for the low-rank matrix factorization. Extensive comparison experiments demonstrate the accuracy and efficiency of Lingo algorithm. The global convergence of Lingo is guaranteed with theoretical proof, which also verifies the effectiveness of Lingo.