The latest papers from the Royal Society Journals

Song and the song control pathway in the brain can develop independently of exposure to song in the sedge warbler by Dr S Leitner, Dr J Nicholson, Dr B Leisler, Dr T J DeVoogd and Professor CK Catchpole
Bird song, like human speech, is thought to be learned from other individuals at an early stage in life. We raised nestling birds in special cages where they could not hear songs from other birds. After one year we recorded their songs and compared them to the songs of other birds who had been able to hear songs throughout the year. There were no differences in basic song structure, nor in the special areas of the brain which control song production. These results suggest that even complex bird songs can develop without the influence of learning from others.
Contact: Dr Stefan Leitner, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX

Validation of Bateman`s principles: a genetic study of sexual selection and mating patterns in the rough-skinned newt by Dr AG Jones, Dr JR Arguello and Professor SJ Arnold
One of the most influential early studies of mating patterns and sexual selection was conducted by AJ Bateman over 50 years ago. In his study of intermale mating competition in flies, Bateman delineated three principles related to the operation of sexual selection in natural populations. Since then, these principles have been formalized into quantitative measures of the mating system, with explicit connections to selection theory. However, the utility of Bateman’s principles has been hotly debated over the last two decades. Our study is the first to quantify all three of the measures based on Bateman’s principles along with a direct assessment of the intensity of sexual selection in any natural population. Our results support the idea that Bateman’s principles provide the best available methods for the quantification of mating patterns with respect to sexual selection in natural populations.
Contact: Dr Adam Jones, School of Biology, Georgia Institute of Technology, 310 Ferst Drive, ATLANTA, GA 30332, USA

Scaling in stream communities by Dr PE Schmid, Dr M Tokeshi and Dr JM Schmid-Araya
In streams, small species occur in higher densities than large ones and the form of this negative relationship can help us to understand how species use resources as a function of their size. However, more species are intermediate-sized, while there are fewer small and large one. Seasonally collated data sets of 602 species from two geographically separate stream communities, the Seebach (Austria) and the Afon Mynach (Wales), displayed a very similar relationship between density and size, indicating a seasonally convergent scaling relationship in both streams. This pattern may be explained by intermediate to large species, which relate to temporal variations of habitat complexity, suggesting that habitat structure constrains stream organisms.
Contact: Dr Peter Schmid, School of Biological Sciences, Queen Mary, University of London, LONDON, E1 4NS

Pattern discrimination in a hawkmoth: innate preferences, learning performance and ecology by Dr A Kelber
Spatial patterns are important cues for flower detection and recognition by nectar-feeding insects. In this paper, I present a first proof of pattern learning abilities in a moth and discuss reasons for the limitations of their pattern learning. The hummingbird hawkmoth learns to associate patterns with a food reward. However, it has a strong innate preference for flower-like patterns and does not learn to avoid them. These patterns help pollinators to detect flowers and to find the nectar. Hovering insects such as hawkmoths depend more strongly on these guides and should not abolish their preferences as easily as other insects.
Contact: Dr Almut Kelber, Department of Cell and Organism Biology, Vision Group, Lund University, Helgonavagen 3, S-22642 LUND, Sweden

Copulatory courtship signals male genetic quality in cucumber beetles by Professor DW Tallamy, Dr MB Darlington , Dr JD Pesek and Dr BE Powell
In the spotted cucumber beetle males court females during copulation by stroking them with their antennae. Females accept the sperm of fast-stroking males and reject sperm from slow-stroking males by relaxing or constricting muscles distorting the vaginal duct. We tested whether such female control results in direct benefits for the discriminating female or genetic benefits that appear in her offspring. We found that courtship after copulation has begun provides females with a reliable and honest signal of the genetic quality of courting males. This demonstrates the importance of female choice, even when it occurs after copulation has begun.
Contact: Professor Douglas Tallamy, Department Entomology & Applied Ecology, University of Delaware, 216 Townsend Hall, NEWARK, DE 19717-1303, USA

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

Numerical and experimental characterisation of a family of two-roll-mill flows by Professor T Price, Professor T Mullin and Dr JJ Kobine
Somewhat paradoxically, the extent to which fluids mix together when stirred is actually determined by the number of places where there is no flow at all. This notion is explored in detail here in a flow where a single fluid is stirred by two rotating cylinders. Laboratory experiments and computer calculations reveal that far more of these so called stagnation points exist than was previously thought. The findings have implications for a wide range of industrial flows where mixing is required. It seems that many of these could become much more efficient simply by altering the sequence in which they are stirred.
Contact: Dr JJ Kobine, DAMTP, University of Cambridge, Silver Street, CAMBRIDGE, CB3 9EW

Stability and bifurcation of inflation of elastic cylinders by Dr Y-C Chen and Dr DM Haughton
Many real world problems can be classified as either linear or nonlinear. In general linear problems are well understood. Nonlinear problems are much more complicated. This paper studies the nonlinear stability of an inflated cylindrical shell. When such a shell becomes unstable we can expect it to change its shape by buckling. The cylindrical shell is just a vehicle to examine the underlying mathematics which can be used for other similar problems. Future studies will try to remove some of the simplifying assumptions we have made. This would then lead to a very useful and powerful mathematical tool in the analysis of the stability of structures.
Contact: Dr Y-C Chen, Department of Mechanical Engineering, University of Houston, HOUSTON, TX 77204-4792, USA

The nearly isotropic behaviour of high-rank nonlinear sequentially laminated composites by Dr I Hariton and Dr G De Botton
A composite is a material made up of a few constituents, and if in at least one the relation between the electric potential and the current is nonlinear, the composite is a nonlinear one. We examine whether one can construct such composites whose behaviour is isotropic, that is, its behaviour doesn`t change as the direction of the applied potential is varied. To this end we slice the two constituents and layer the slices to obtain a multilayered Rank-1 sandwich. To create a Rank-2 laminate, we slice this Rank-1 sandwich along a different direction and layer the slices with layers from one of the constituents. This processes is repeated many times to obtain a high-rank sequentially laminated composite. We demonstrate that with appropriate choice of the slicing directions, the behaviours of these nonlinear composites tend to be isotropic.
Control: Dr Gal De Botton, Mechanical Engineering, Ben-Gurion University of the Negev, PO Box 653, BEER-SHIVA, 84105, ISRAEL

Nonlinear dynamics of a nematic liquid crystal in the presence of a shear flow by Dr E Vicente Alonso, Professor AA Wheeler and Professor TJ Sluckin
Nematic liquid crystals are materials consisting of long molecules which are used in many modern devices, eg flat panel computer displays and are found in soaps, lubricants and in many living systems. In this work we perform a theoretical investigation of a simple liquid crystal when it is flowing. Depending on how strong the flow is the molecules exhibit a variety of behaviour: Wither on average they line up in a mean direction that depends on the magnitude of the flow or they show time dependent behaviour by oscillating back and forth or alternatively continually rotating. This work is important because for the first time it provides a comprehensive description of all the different types of behaviour depending on the temperature of the liquid crystal and the strength of the flow.
Contact: Professor Adam Wheeler, Faculty of Mathematical Studies, University of Southampton, Highfield, SOUTHAMPTON, SO9 5NH

Band gaps and elastic waves in disordered stacks: normal incidence by Dr SB Platts, Dr NV Movchan, Professor RC McPhedran and Professor AB Movchan
We consider an infinite, in the horizontal direction, array of uni-directional channels placed within an elastic medium. In the vertical direction the number of layers is finite. An elastic plane wave hits the stack of channels and some of the energy gets reflected whereas the remaining energy is transmitted through the system. We develop an efficient mathematical model that enables us to evaluate the transmission and reflection properties of this system for a wide frequency range. The results are compared with the studies of phononic band gap structures. This work gives clear ideas for the design of filters and polarizers of elastic waves.
Contact: Professor Alexander Movchan, Mathematical Sciences, University of Liverpool, M and O Building, LIVERPOOL, L69 3BX

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