Causality constraints in AdS/CFT from conformal collider physics and Gauss-Bonnet gravity

We explore the relation between positivity of the energy constraints in conformal field theories and causality in their dual gravity description. Our discussion involves CFTs with different central charges whose description, in the gravity side, requires the inclusion of quadratic curvature corrections. It is enough, indeed, to consider the Gauss-Bonnet term. We find that both sides of the AdS/CFT correspondence impose a restriction on the Gauss-Bonnet coupling. In the case of 6d supersymmetric CFTs, we show the full matching of these restrictions. We perform this computation in two ways. First by considering a thermal setup in a black hole background. Second by scrutinizing the scattering of gravitons with a shock wave in AdS. The different helicities provide the corresponding lower and upper bounds. We generalize these results to arbitrary higher dimensions and comment on some hints and puzzles they prompt regarding the possible existence of higher dimensional CFTs and the extent to which the AdS/CFT correspondence would be valid for them.Comment: 31 pages, 5 figures; v2: typos fixed, cosmetic amendments and references adde

Genome sequence of Yersinia pestis, the causative agent of plague

The Gram-negative bacterium Yersinia pestis is the causative agent of the systemic invasive infectious disease classically referred to as plague(1), and has been responsible for three human pandemics: the Justinian plague (sixth to eighth centuries), the Black Death (fourteenth to nineteenth centuries) and modern plague (nineteenth century to the present day). The recent identification of strains resistant to multiple drugs(2) and the potential use of Y. pestis as an agent of biological warfare mean that plague still poses a threat to human health. Here we report the complete genome sequence of Y. pestis strain CO92, consisting of a 4.65-megabase (Mb) chromosome and three plasmids of 96.2 kilobases (kb), 70.3 kb and 9.6 kb. The genome is unusually rich in insertion sequences and displays anomalies in GC base-composition bias, indicating frequent intragenomic recombination. Many genes seem to have been acquired from other bacteria and viruses (including adhesins, secretion systems and insecticidal toxins). The genome contains around 150 pseudogenes, many of which are remnants of a redundant enteropathogenic lifestyle. The evidence of ongoing genome fluidity, expansion and decay suggests Y. pestis is a pathogen that has undergone large-scale genetic flux and provides a unique insight into the ways in which new and highly virulent pathogens evolve.</p

Determinants of microbat communities in urban forest remnants: a rapid landscape scale assessment

Urbanisation affects fauna in many ways; with some species persisting and going on to dominate urban habitats, while other species decline over time due to habitat disturbance and modification. Microbats comprise a major component of remnant mammalian fauna in urban areas but we have a comparatively poor understanding of how they respond to urbanisation compared to other taxonomic groups. We investigated the impacts of an urban gradient on microbat communities of habitat remnants on the Gold Coast, south-east Queensland, Australia. We conducted acoustic surveys of 34 sites categorised as urban, peri-urban or rural, with an additional five reference sites. A combination of landscape and habitat elements were quantified for each site and their influence on the richness and calling activity of microbats determined. Overall, more microbat species were detected in reference sites followed by peri-urban sites. Rural and urban sites had similar richness, but only 50 % overlap in species recorded. After accounting for sampling effort peri-urban sites were found to have the greatest species richness and calling activity. Three species accounted for 45.4 % of the variation in microbat species detected. Using generalised linear mixed models we found that site area and the extent of urban development in the landscape (i.e. urbanisation index) had the greatest impact on microbat richness and calling activity. Models including logging (clearfelling) and hollow-bearing tree measures were also important. Our results support the use of the urbanisation gradient as a key measure to quantify the impacts of urbanisation on biodiversity. Logging history plays an important role across the landscape as it is a potential driver of other landscape variables such as tree species diversity, stand density and hollow-bearing tree density.Griffith Sciences, Griffith School of EnvironmentNo Full Tex