Latest Papers From The Royal Society Journals

PROCEEDINGS B (Biological sciences)
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Testosterone increases perceived dominance but not attractiveness in human males by Dr JP Swaddle and Dr GW Reierson
Testosterone affects the growth of particular facial features and also suppresses the immune system. Researchers have theorized that only the highest quality males can have high levels of testosterone and bare the immune-function handicap it imposes. Therefore, women could use facial testosterone to assess mate quality. We digitally manipulated male faces to mimic growth under differing levels of testosterone and asked women to choose the most attractive and most dominant looking face. Contrary to predictions, there was no preference for increased testosterone in male faces, although high testosterone faces did look more dominant. It seems that facial features, whose growth is affected by testosterone, do not reveal male mate quality.
Contact: Professor John Swaddle, Biology Department, College of William & Mary, WILLIAMSBURG, VA 23187-8795, USA

Size symmetry of competition alters biomass-density relations by Dr P Stoll, Dr J Weiner, Dr H Muller-Landau, Dr E Muller and Professor Toshihiko Hara
As crowded populations of plants develop, the growth of some plants is accompanied by the death of others, a process called density-dependent mortality or "self-thinning". The relationship between survivor density and biomass differs among species, but we do not know why. A computer model suggests that a large size advantage in competition among individuals results in faster death and less biomass. We compared the process of mortality in normal and transgenic Arabidopsis plants that can`t change their growth form when shaded by neighbours. The transgenics` inflexibility gave larger individuals an increased advantage, increasing mortality and reducing the amount of biomass. This could explain differences among species.
Contact: Dr Peter Stoll, Institut of Environmental Sciences, Section Biology, University of Basel, ST. JOHANNS-VORSTADT 10, CH-4056, Switzerland

Egg size evolution in aquatic enviroments: does oxygen availability constrain size? by Dr S Einum, Dr AP Hendry and Dr IA Fleming
For many aquatic organisms, egg survival may be limited by access to oxygen, and large eggs have been thought to be at a disadvantage under anoxic conditions. Here we show that this conclusion depends critically on how rapidly metabolic rate increases with mass. By measuring oxygen consumption in Atlantic salmon eggs we find that oxygen consumption increases so slowly with mass that an increase in size causes an increased tolerance towards anoxic conditions, in contrast to conventional expectations. This prediction is supported from an experimental test of brown trout egg survival. We also demonstrate that large females can reduce nest-specific oxygen consumption to a greater extent than small females by increasing their egg size, and suggest that this may help explain the positive correlation between adult body size and egg size observed in fish that cluster their eggs.
Contact: Dr Sigurd Einum, Norwegian Institute for Nature Research, Tungasletta 2, N-7005 Trondheim, Norway

Older males signal more reliably by Dr SR Proulx, Dr T Day and Professor L Rowe
Females of many species make mating decisions based on visible ornaments that males display. One explanation for the stability of these signalling systems is that costs of producing the display are higher for low quality males. We have explored the stability of male signals when breeding is spread over multiple years or seasons. We show that in long-lived species, even when displays are more costly for low quality males, male displays will not necessarily be correlated with male quality. Moreover, this pattern is more pronounced in younger males, suggesting that older males signal their quality in a more reliable fashion. Females may prefer older males, not because they are better, but because they provide more accurate information.
Contact: Dr Stephen Proulx, Department of Biology, University of Oregon, EUGENE, OR 97403-1210, USA

PROCEEDINGS A (Mathematical, Physical & Engineering Sciences http://www.catchword.com/rsl/13645021/previews/contp1-1.htm

Knotted reaction-diffusion waves by Dr S McDermott, Dr AJ Mulholland and Professor J Gomatam
The aim of this research is to further the fundamental understanding of the mechanisms which control the functioning of cardiac tissue by analysing a mathematical model. The periodic contractions of the heart are governed by waves of electrical activity propagating along the muscle fibres. The healthy heart supports a series of regular plane waves produced by the sinoatrial node whereas the diseased heart often gives rise to spiral waves which meander on the heart surface, interacting with each other and causing the heart to beat in a highly irregular fashion. In three dimensions these spiral waves manifest themselves as scroll waves which can sometimes be twisted and knotted. This paper shows the viability of such knotted structures and makes predictions about their dynamics. These results will provide clinicians and experimentalists with a fuller understanding of the complex electrical patterns found in the unhealthy heart, how these patterns arise and how to mitigate against them.
Contact: Dr Anthony Mulholland, Department of Mathematics, University of Strathclyde, 26 Richmond Street, GLASGOW, G1 1XH

Periodic structures in waveguides by Dr CM Linton and Dr M McIver
The existence of certain localized disturbances near to periodic structures in waveguides has been established. These oscillations, which are significant in the context of water waves and acoustics, had previously only been computed for some particular geometries.
Contact: Dr Chris Linton, Mathematical Sciences, Loughborough University, LOUGHBOROUGH, LE11 3TU

The domain derivative in rough surface scattering and rigorous estimates for first order
perturbation theory by Dr SN Chandler-Wilde and Dr R Potthast
This paper is concerned with analysing problems of wave scattering by large surfaces, for example scattering of radar waves by sea or ground surfaces, such as occurs in remote sensing. The results we obtain are of two types. Firstly, we provide a mathematical justification for the validity of certain approximate formulae for calculating the scattering which occurs. These approximate formulae are already widely used by engineers, so that it is desirable to provide checks on their accuracy. Secondly we provide formulae for calculating how the scattered waves change when the surface elevations changes slightly. These formulae are primarily of value in algorithms for imaging surface profiles from measurements of scattered radar waves.
Contact: Dr Simon Chandler-Wilde, Mathematical Sciences, Brunel University, UXBRIDGE, UB8 3PH

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