Particle Motion in the Rotating Black Ring Metric

In this paper, the equations of motion for geodesics in the neutral rotating Black Ring metric are derived and the separability of these equations is considered. The bulk of the paper is concerned with sets of solutions where the geodesic equations can be examined analytically - specifically geodesics confined to the axis of rotation, geodesics restricted to the equatorial plane, and geodesics that circle through the centre of the ring. The geodesics on the rotational axis behave like a particle in a potential well, while the geodesics confined to the equatorial plane mimic those of the Schwarzschild metric. It is shown that it is impossible to have circular orbits that pass through the ring, but some numerical results are presented which suggest that it is possible to have bound orbits that circle through the ring.Comment: 36 pages, 19 figures, updated references, section 5 modified to remove ambiguity in discussio

A Charged Doubly Spinning Black Ring

This paper calculates the general form of a 5d metric when fundamental string and momentum charges are added. This is accomplished using the standard method of boosting and T-dualising a solution to Einstein's equations, where the solution has three Killing vectors and is expressed in a generic form. The thermodynamical properties of the charged solution are derived and the physical implications of the solution are then examined with the two-charge dual spinning black ring being used as an example.Comment: 22 pages, 4 figure

Explorations of four and five dimensional black hole spacetimes

This thesis concentrates on four and five dimensional black holes and their associated geodesies. Some coordinate charts are presented, which are useful in the analysis of both static and rotating black holes, and their mathematical properties investigated before some methods of solving Einstein's vacuum field equations are examined. The Myers-Perry black hole metric is derived before going on to describe the Inverse Scattering Method of generating new vacuum solutions. The Inverse Scattering Method is used to generate the single and doubly spinning black ring metrics and then the physical properties of these solutions is explored in detail. The latter part of this thesis looks at different ways of visualising geodesies in various spacetimes and examines the pros and cons of each particular method, as well as looking at several examples of geodesies with different parameters. The geodesies of the singly spinning black ring are calculated and it is shown that they cannot in general be analytically integrated. In light of this, some restricted analytic scenarios are investigated with the intention of gaining some insight into how the geodesies behave in the spacetime as a whole. Finally, a method is presented which allows string charges to be added to any vacuum solution to Einstein's equations. The properties of this new charged solution are then compared with the neutral starting solution. The doubly spinning black ring is used as a model to demonstrate how the method can be used to charge up a specific black hole solution and the resulting thermodynamic properties of this charged doubly spinning black ring are then examined

Microbe profile : Corynebacterium diphtheriae - an old foe always ready to seize opportunity

Diphtheria AB toxin mode of action. The diphtheria AB exotoxin consists of two polypeptide chains - A and B which are linked by a disulfide bridge. The B chain binds to the heparin-binding epidermal growth factor precursor on eukaryotic cells and is endocytosed. Acidification of the endosome results in a conformational change to the A and B chains and breaking of the disulphide bridge. The B chain remains in the endosome, but the A chain is translocated to the cytoplasm where it ADP-ribosylates host eEF-2, blocking protein synthesis which leads to cell death. Corynebacterium diphtheriae is a globally important Gram-positive aerobic Actinobacterium capable of causing the toxin-mediated disease, diphtheria. Diphtheria was a major cause of childhood mortality prior to the introduction of the toxoid vaccine, yet it is capable of rapid resurgence following the breakdown of healthcare provision, vaccination or displacement of people. The mechanism and treatment of toxin-mediated disease is well understood, however there are key gaps in our knowledge on the basic biology of C. diphtheriae particularly relating to host colonisation, the nature of asymptomatic carriage, population genomics and host adaptation

Comparison of Various Types of Milk Sampling Devices

Volatiles of peach (Prunus persica L., cultivar, Gleason Early Elberta) fruit were studied by gas-liquid chromatography, thin-layer chromatography, and infrared spectrometry. Hard mature, firm mature, soft mature, tree ripe, and artificially ripened hard mature fruit obtained from four seasons, 1964 to 1967, were used. A total of 86 peaks were observed in the chromatogram of the tree ripe peach volatiles. Major components of the volatiles identified were mainly esters, gamma and delta lactones, aldehydes, alcohols, and terpenes. In general, concentration of the volatile components were found to increase with the maturity of the fruit. However, that of the artificially ripened fruit did not reach the same level of the tree ripe fruit

Genomic analyses confirm close relatedness between Rhodococcus defluvii and Rhodococcus equi (Rhodococcus hoagii)

Rhodococcus defluvii strain Ca11T was isolated from a bioreactor involved in extensive phosphorus removal. We have sequenced the whole genome of this strain and our comparative genomic and phylogenetic analyses confirm its close relatedness with Rhodococcus equi (Rhodococcus hoagii) strains, which share >80% of the gene content. The R. equi virulence plasmid is absent though most of the chromosomal R. equi virulence-associated genes are present in R. defluvii Ca11T. These data suggest that although R. defluvii is an environmental organism, it has the potential to colonise animal hosts

DevA, a GntR-like transcriptional regulator required for development in streptomyces coelicolor

The gram-positive filamentous bacterium Streptomyces coelicolor has a complex developmental cycle with three distinct phases: growth of the substrate mycelium, development of reproductive structures called aerial hyphae, and differentiation of these aerial filaments into long chains of exospores. During a transposon mutagenesis screen, we identified a novel gene (devA) required for proper development. The devA mutant produced only rare aerial hyphae, and those that were produced developed aberrant spore chains that were much shorter than wild-type chains and had misplaced septa. devA encodes a member of the GntR superfamily, a class of transcriptional regulators that typically respond to metabolite effector molecules. devA forms an operon with the downstream gene devB, which encodes a putative hydrolase that is also required for aerial mycelium formation on R5 medium. S1 nuclease protection analysis showed that transcription from the single devA promoter was temporally associated with vegetative growth, and enhanced green fluorescent protein transcriptional fusions showed that transcription was spatially confined to the substrate hyphae in the wild type. In contrast, devAB transcript levels were dramatically upregulated in a devA mutant and the devA promoter was also active in aerial hyphae and spores in this background, suggesting that DevA might negatively regulate its own production. This suggestion was confirmed by gel mobility shift assays that showed that DevA binds its own promoter region in vitro

Evolution, epidemiology and diversity of Corynebacterium diphtheriae : new perspectives on an old foe

Diphtheria is a debilitating disease caused by toxigenic Corynebacterium diphtheriae strains and has been effectively controlled by the toxoid vaccine, yet several recent outbreaks have been reported across the globe. Moreover, non-toxigenic C. diphtheriae strains are emerging as a major global health concern by causing severe pharyngitis and tonsillitis, endocarditis, septic arthritis and osteomyelitis. Molecular epidemiological investigations suggest the existence of outbreak-associated clones with multiple genotypes circulating around the world. Evolution and pathogenesis appears to be driven by recombination as major virulence factors, including the tox gene and pilus gene clusters, are found within genomic islands that appear to be mobile between strains. The number of pilus gene clusters and variation introduced by gain or loss of gene function correlate with the variable adhesive and invasive properties of C. diphtheriae strains. Genomic variation does not support the separation of C. diphtheriae strains into biovars which correlates well with findings of studies based on multilocus sequence typing. Genomic analyses of a relatively small number of strains also revealed a recombination driven diversification of strains within a sequence type and indicate a wider diversity among C. diphtheriae strains than previously appreciated. This suggests that there is a need for increased effort from the scientific community to study C. diphtheriae to help understand the genomic diversity and pathogenicity within the population of this important human pathogen

Draft genome sequence of root-associated sugarcane growth promoting Microbispora sp. GKU 823

The endophytic plant growth promoting Microbispora sp. GKU 823 was isolated from the roots of sugarcane cultivated in Thailand. It has an estimated 9.4 Mbp genome and a G+C content of 71.3%. The genome sequence reveals several genes associated with plant growth-promoting traits and extensive secondary metabolite biosyntheses

Duplication and Evolution of devA-Like Genes in Streptomyces Has Resulted in Distinct Developmental Roles

Understanding morphological transformations is essential to elucidating the evolution and developmental biology of many organisms. The Gram-positive soil bacterium, Streptomyces coelicolor has a complex lifecycle which lends itself well to such studies. We recently identified a transcriptional regulator, devA, which is required for correct sporulation in this organism, with mutants forming short, mis-septate aerial hyphae. devA is highly conserved within the Streptomyces genus along with a duplicate copy, devE. Disruption of devE indicates this gene also plays a role in sporulation; however the phenotype of a devE mutant differs from a devA mutant, forming long un-septate aerial hyphae. Transcriptional analysis of devA and devE indicates that they are expressed at different stages of the lifecycle. This suggests that following duplication they have diverged in regulation and function. Analysis of fully sequenced actinomycete genomes shows that devA is found in a single copy in morphologically simpler actinobacteria, suggesting that duplication has lead to increased morphological complexity. Complementation studies with devA from Salinispora, which sporulates but does not form aerial hyphae, indicates the ancestral gene cannot complement devA or devE, suggesting neo-functionalisation has occurred. Analysis of the synonymous and non-synonymous nucleotide changes within the devA paralogues suggest subfunctionalisation has occurred as both copies have diverged from the ancestral sequences. Divergence is also asymmetric with a higher level of functional constraint observed in the DNA binding domain compared with the effector binding/oligomerisation domain, suggesting diversification in the substrate specificity of these paralogues has contributed to their evolution