Epidemiology and disease burden of tuberculosis in children: a global perspective

Our understanding of the tuberculosis (TB) epidemic in children is incomplete due to challenges in diagnosis and reporting. Children have also been largely excluded from research and advocacy. However, the tide appears to be turning and interest in pediatric TB is increasing. In this article, we explore the epidemiology of childhood TB by first reviewing the natural history of TB in children and the factors that impact on each of the stages from exposure to disease. We then discuss how these factors affect what we see at a country and regional level. Finally, we assess the burden of childhood TB globally. © 2014 Seddon and Shingadia

Evidence for polarised boron in Co-B and Fe-B alloys

By exploiting the tunability of synchrotron radiation in measurements of spin-resolved photoemission it has proved possible to obtain information on the polarisation of the valence electrons of Co-B and Fe-B amorphous magnetic alloys, Both the spin-integrated and spin-resolved energy distribution curves show a marked dependence on photon energy indicating that the p states of boron hybridise with the d states of the transition metals giving rise to mixed states in the binding energy range 1 to 5 eV, The observed polarisation and spin-resolved densities of states imply that in the above restricted energy range there is a net negative polarisation of the boron states

Entropy-driven formation of the gyroid cubic phase

We show, by computer simulation, that tapered or pear-shaped particles, interacting through purely repulsive interactions, can freely self-assemble to form the three-dimensionally periodic, gyroid cubic phase. The Ia3d gyroid cubic phase is formed by these particles both on compression of an isotropic configuration and on expansion of a smectic A bilayer arrangement. For the latter case, it is possible identify the steps by which the topological transformation from non-intersecting planes to fully interpenetrating, periodic networks takes place</p

Fine-scale movement of the European hedgehog: An application of spool-and-thread tracking

The European hedgehog is a significant predator species of rare and endangered ground-nesting birds in the riverbeds of the Waitaki Basin, South Island, New Zealand. Studies focusing on the movements and habits of this species have generally been limited to broad-scale radio-tracking studies or incidental trap-catch data. Within our study, we aimed to investigate the finer scale movement patterns of the hedgehog in relation to vegetation structure by using spool-and-thread tracking. We captured 30 hedgehogs (15 female, 15 male) within the study area, and spool-and-thread-tracked the movements of each over a single night. Only two of the 30 animals moved onto the gravel areas of the riverbeds where birds nest - hedgehogs may therefore not target birds' nests as a primary prey source, but rather as a secondary prey item. The movement paths were all non-random, and males demonstrated particular linearity in their tracks. This straighter and more directed movement may be due to more intensive male search at this time of the year. We also assessed habitat use using a very high resolution habitat map (derived from Ikonos 4-m-resolution satellite image). Dense grassland was the most selected habitat type, perhaps because insect prey are at a higher density in this vegetation type. Hedgehogs (particularly males) also used boundaries of all habitat types significantly more than the centre of habitat patches. We found the spool-and-thread tracking technique does have limitations: (1) it could be inappropriate for animals exhibiting a significant escape response; (2) the data do not include a temporal dimension. However, these problems were not considered relevant for this study. Fine-scale studies such as this can provide increased power when investigating the ecology of species at a scale relevant to trap placement

Accurate modelling for the analysis and design of liquid-crystal-based microwave devices

Liquid crystal substrates have been shown to provide the means to develop low-cost, reconfigurable, adaptive and tuneable microwave and MM-wave devices for mobile and wireless communication systems. However, techniques for the characterisation of materials, device fabrication and design are necessary in order to take maximum advantage of the possibilities that these materials offer. This includes appropriate modelling methods to simulate accurately the switching behaviour of the liquid crystal and the characteristics of the wave propagation through the devices, taking full consideration of the point-by-point variation of the material tensor permittivity. We describe these techniques here and show their application in the design of a meander-line phase shifter

Calculation of the Phase Behavior of Lipids

The self-assembly of monoacyl lipids in solution is studied employing a model in which the lipid's hydrocarbon tail is described within the Rotational Isomeric State framework and is attached to a simple hydrophilic head. Mean-field theory is employed, and the necessary partition function of a single lipid is obtained via a partial enumeration over a large sample of molecular conformations. The influence of the lipid architecture on the transition between the lamellar and inverted-hexagonal phases is calculated, and qualitative agreement with experiment is found.Comment: to appear in Phys.Rev.

Ultrathin epitaxial Fe films in vicinal GaAs(001): A study by spin-resolved photoelectron spectroscopy

Thin epitaxial Fe films have been grown on vicinal GaAs(001) substrates and their remanent magnetic properties and the degree of substrate atom diffusion investigated using synchrotron-based photoelectron spectroscopy. The vicinal Fe films, though exhibiting greater As diffusion than their singular homologues, displayed better film quality both from the structural and the magnetic points of view. The spin-resolved valence spectra of the vicinal films resemble those for crystalline bulk Fe at lower film thicknesses than for singular films