Coupling models of cattle and farms with models of badgers for predicting the dynamics of bovine tuberculosis (TB)

Bovine TB is a major problem for the agricultural industry in several countries. TB can be contracted and spread by species other than cattle and this can cause a problem for disease control. In the UK and Ireland, badgers are a recognised reservoir of infection and there has been substantial discussion about potential control strategies. We present a coupling of individual based models of bovine TB in badgers and cattle, which aims to capture the key details of the natural history of the disease and of both species at approximately county scale. The model is spatially explicit it follows a very large number of cattle and badgers on a different grid size for each species and includes also winter housing. We show that the model can replicate the reported dynamics of both cattle and badger populations as well as the increasing prevalence of the disease in cattle. Parameter space used as input in simulations was swept out using Latin hypercube sampling and sensitivity analysis to model outputs was conducted using mixed effect models. By exploring a large and computationally intensive parameter space we show that of the available control strategies it is the frequency of TB testing and whether or not winter housing is practised that have the most significant effects on the number of infected cattle, with the effect of winter housing becoming stronger as farm size increases. Whether badgers were culled or not explained about 5%, while the accuracy of the test employed to detect infected cattle explained less than 3% of the variance in the number of infected cattle

Chemical characterization of extra layers at the interfaces in MOCVD InGaP/GaAs junctions by electron beam methods

Electron beam methods, such as cathodoluminescence (CL) that is based on an electron-probe microanalyser, and (200) dark field and high angle annular dark field (HAADF) in a scanning transmission electron microscope, are used to study the deterioration of interfaces in InGaP/GaAs system with the GaAs QW on top of InGaP. A CL emission peak different from that of the QW was detected. By using HAADF, it is found that the GaAs QW does not exist any longer, being replaced by extra interlayer(s) that are different from GaAs and InGaP because of atomic rearrangements at the interface. The nature and composition of the interlayer(s) are determined by HAADF. Such changes of the nominal GaAs QW can account for the emission observed by CL

Facile mechanosynthesis of amorphous zeolitic imidazolate frameworks.

A fast and efficient mechanosynthesis (ball-milling) method of preparing amorphous zeolitic imidazolate frameworks (ZIFs) from different starting materials is discussed. Using X-ray total scattering, N(2) sorption analysis, and gas pycnometry, these frameworks are indistinguishable from one another and from temperature-amorphized ZIFs. Gas sorption analysis also confirms that they are nonporous once formed, in contrast to activated ZIF-4, which displays interesting gate-opening behavior. Nanoparticles of a prototypical nanoporous substituted ZIF, ZIF-8, were also prepared and shown to undergo amorphization

Synthesis and structural characterisation of single wall carbon nanotubes filled with ionic and covalent materias

Carbon nanombes have hollow interiors with internal diameters ranging from 0.5 - 20 nm although more typically 1 - 4 nm. It is now well established that these internal cavities can be filled with crystalline and molecular materials. Filling of single walled carbon nanotubes (SWNTs) are normally filled by direct mixing of the molten filling material and the nanotubes at elevated temperature. Characterisation of filled carbon nanotubes relies mainly on high-resolution transmission electron microscopy (HRTEM) and extended resolution HRTEM techniques. The crystals formed within the narrower SWNTs are often only a few atoms in cross section with a large proportion of atoms lying on the surface of the encapsulated crystals. An extreme example is in the case of a 2 x 2 crystal of potassium iodide which is effectively an 'all surface' crystal. The structures of the nanocrystals encapsulated inside SWNTs show other significant differences compared to the corresponding bulk materials. For example, inter-atomic differences can be substantially greater (i.e. by as much as similar to20%) for SWNT encapsulated materials. Several examples of filled SWNTs are described including those filled with simple metal halide salts, covalent metal halides and molecular species as in o-carborane