Implicit large-eddy simulation of a wingtip vortex

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordIn this article, recent developments in numerical methods for performing a large-eddy simulation of the formation and evolution of a wingtip vortex are presented. The development of these vortices in the near wake, in combination with the large Reynolds numbers present in these cases, makes these types of test cases particularly challenging to investigate numerically. First, an overview is given of the spectral vanishing viscosity/implicit large-eddy simulation solver that is used to perform the simulations, and techniques are highlighted that have been adopted to solve various numerical issues that arise when studying such cases. To demonstrate the method's viability, results are presented from numerical simulations of flow over a NACA 0012 profile wingtip at R ec = 1.2 × 10 6 and they are compared against experimental data, which is to date the highest Reynolds number achieved for a large-eddy simulation that has been correlated with experiments for this test case. The model in this paper correlates favorably with experiment, both for the characteristic jetting in the primary vortex and pressure distribution on the wing surface. The proposed method is of general interest for the modeling of transitioning vortex-dominated flows over complex geometries.The authors acknowledge support from the United Kingdom Turbulence Consortium (UKTC) under grant EP/L000261/1 as well as from the Engineering and Physical Sciences Research Council (EPSRC) for access to ARCHER UK National Supercomputing Service (http://www.archer.ac.uk). DM acknowledges supported by the Laminar Flow Control Centre funded by Airbus/EADS and EPSRC under grant EP/I037946. SJS additionally acknowledges Royal Academy of Engineering support under their research chair scheme. We also acknowledge the support from the Imperial College London High Performance Computing facilities

The occurrence of Toxocara malaysiensis in cats in China, confirmed by sequence-based analyses of ribosomal DNA

Non-isotopic polymerase chain reaction (PCR)- based single-strand conformation polymorphism and sequence analyses of the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) were utilized to genetically characterise ascaridoids from dogs and cats from China by comparison with those from other countries. The study showed that Toxocara canis, Toxocara cati, and Toxascaris leonina from China were genetically the same as those from other geographical origins. Specimens from cats from Guangzhou, China, which were morphologically consistent with Toxocara malaysiensis, were the same genetically as those from Malaysia, with the exception of a polymorphism in the ITS-2 but no unequivocal sequence difference. This is the first report of T. malaysiensis in cats outside ofMalaysia (from where it was originally described), supporting the proposal that this species has a broader geographical distribution. The molecular approach employed provides a powerful tool for elucidating the biology, epidemiology, and zoonotic significance of T. malaysiensis

Trail and teritorial communication in social insects

The social properties of insect colonies are sometimes described in seemingly contradictory terms. As pinnacles of biological complexity they are superorganisms and their emergent, colony-level characteristics are often referred to in terms of their elaborate and sophisticated nature. Yet the mechanisms that mediate social interactions and group phenomena, after empirical or theoretical analysis, are simple and parsimonious. This complexity-mediated-by-simplicity paradigm provides a heuristic approach to the analysis of the basic behavioral characteristics of the individual members of an insect society and the regulatory mechanisms of cooperative response, which are the fundamental elements from which colony level behavior is derived. Inevitably, the dissection and reconstruction of insect social organization involves semiochemicals, because the principal sensory modality of integration, social coordination, and assembly of colony-level patternsis olfaction