Thermodynamics of phase transition in higher dimensional AdS black holes

We investigate the thermodynamics of phase transition for $(n+1)$ dimensional Reissner Nordstrom (RN)-AdS black holes using a grand canonical ensemble. This phase transition is characterized by a discontinuity in specific heat. The phase transition occurs from a lower mass black hole with negative specific heat to a higher mass black hole with positive specific heat. By exploring Ehrenfest's scheme we show that this is a second order phase transition. Explicit expressions for the critical temperature and critical mass are derived. In appropriate limits the results for $(n+1)$ dimensional Schwarzschild AdS black holes are obtained.Comment: LaTex, 11 pages, 5 figures, To appear in JHE

A unified picture of phase transition: from liquid-vapour systems to AdS black holes

Based on fundamental concepts of thermodynamics we examine phase transitions in black holes defined in Anti-de Sitter (AdS) spaces. The method is in line with that used a long ago to understand the liquid-vapour phase transition where the first order derivatives of Gibbs potential are discontinuous and Clausius-Clapeyron equation is satisfied. The idea here is to consider the AdS black holes as grand-canonical ensembles and study phase transition defined by the discontinuity of second order derivatives of Gibbs potential. We analytically check that this phase transition between the `smaller' and `larger' mass black holes obey Ehrenfest relations defined at the critical point and hence confirm a second order phase transition. This include both the rotating and charged black holes in Einstein gravity.Comment: v3; JHEP style, 11 pages, 1 figure; title is changed, paper rewritten but basic results are unchanged, to appear in JHE

Assessment of performance properties of wetsuits

Wetsuits are an integral part of surfing especially in the southern regions of Australia. There is currently little information about mechanical, comfort and thermal properties of wetsuits. There is a demand from wetsuit manufacturers to better understand the neoprene properties and wetsuit performance. The performance characteristics of eight topselling wetsuits, from both high end and low end of the market, were examined. These characteristics include thickness, elasticity, bursting strength, hydrophobicity, thermal conductivity and seal strength. Tensile assessment revealed that neoprene foam was strong and its stretch recovery was well beyond 1.6 times of the original length. Neoprene was found to be hydrophobic with very low surface energy. High-end wetsuits with higher thickness showed slightly higher thermal resistance than low-end wetsuits, indicating that both thickness and bulk density of neoprene influenced thermal properties. High-end wetsuits with fluid seal were stronger than low-end wetsuits with stitched seal