Do supersymmetric anti-de Sitter black rings exist?

We determine the most general near-horizon geometry of a supersymmetric, asymptotically anti-de Sitter, black hole solution of five-dimensional minimal gauged supergravity that admits two rotational symmetries. The near-horizon geometry is that of the supersymmetric, topologically spherical, black hole solution of Chong et al. This proves that regular supersymmetric anti-de Sitter black rings with two rotational symmetries do not exist in minimal supergravity. However, we do find a solution corresponding to the near-horizon geometry of a supersymmetric black ring held in equilibrium by a conical singularity, which suggests that nonsupersymmetric anti-de Sitter black rings may exist but cannot be "balanced" in the supersymmetric limit.Comment: Latex, 18 pages, 1 figure. v2: minor change

Fire interval and post-fire climate effects on serotinous forest resilience

Background Climate change is eroding forest resilience to disturbance directly through warming climate and indirectly through increasing disturbance activity. Forests characterized by stand-replacing fire regimes and dominated by serotinous species are at risk when the inter-fire period is insufficient for canopy seed bank development and climate conditions for recruitment in the post-fire growing season are unsuitable. Although both factors are critical to serotinous forest persistence, their relative importance for post-fire regeneration in serotinous forests remains poorly understood. To assess the relative effects of each factor, we established plots in severely burned knobcone pine (Pinus attenuata Lemmon) forests in Oregon and California, USA, representing a range of past fire intervals (6 to 31+ years). Specifically, we evaluated effects of fire interval and pre-fire canopy seed bank (proxies for seed supply) and post-fire climate on three metrics of post-fire tree regeneration (seedling density, probability of self-replacement, percent population recovery). Results Seed supply consistently had the strongest effect on post-fire regeneration. Between 6- and 31-year fire intervals, post-fire seedling density increased from 1000 to 100,000 seedlings ha−1, while probability of self-replacement increased from ~ 0 to ~ 100% and percent population recovery increased from 20 to 2000% of the pre-fire population, respectively. Similarly, increasing the canopy seed bank by two orders of magnitude increased seedling density and percent population recovery by two orders and one order of magnitude, respectively, and increased the probability of self-replacement by > 50%. Greater post-fire climatic moisture deficit exacerbated the effect of seed supply; an additional 4–6 years between fires was required under high moisture stress conditions to reach similar regeneration levels as under low moisture stress conditions. Conclusion The overriding effect of seed supply—strongly driven by pre-fire stand age—on post-fire regeneration suggests that altered fire frequency (an indirect effect of climate change) will have a profound impact on serotinous forests. Although direct effects of hot and dry climate are lower in magnitude, they can alter forest recovery where seed supply nears a threshold. These findings reveal how fire interval and climate combine to determine changes in forest cover in the future, informing management and vulnerability mapping

Conservation systematics of the shield-backed trapdoor spiders of the nigrum-group (Mygalomorphae, idiopidae, idiosoma): Integrative taxonomy reveals a diverse and threatened fauna from south-western Australia [dataset]

Supplementary material from: Rix MG, Huey JA, Cooper SJB, Austin AD, Harvey MS (2018) Conservation systematics of the shield-backed trapdoor spiders of the nigrum-group (Mygalomorphae, Idiopidae, Idiosoma): integrative taxonomy reveals a diverse and threatened fauna from south-western Australia. ZooKeys 756: 1-121. https://doi.org/10.3897/zookeys.756.24397 Supplementary material 1: Atlas of morphology : Explanation note: Atlas of morphology for shield-backed trapdoor spiders of the Idiosoma nigrum-group, illustrating a representative selection of male specimens for each species, in five standard views. Supplementary material 2: GenBank data : Explanation note: Spreadsheet of specimens sequenced for the molecular analyses, with associated collection data and GenBank accession numbers. Supplementary material 3: COI dataset : Explanation note: Nexus file of the aligned COI dataset for 82 taxa. Supplementary material 4: FULL dataset : Explanation note: Nexus file of the aligned FULL dataset for 82 taxa. Supplementary material 5: COI p-distances : Explanation note: Spreadsheet with matrix of COI p-distances for 61 sequenced specimens of Idiosoma in the nigrum-group, along with a summary of mean inter- and intra-specific p-distances

Residues and World-Sheet Instantons

We reconsider the question of which Calabi-Yau compactifications of the heterotic string are stable under world-sheet instanton corrections to the effective space-time superpotential. For instance, compactifications described by (0,2) linear sigma models are believed to be stable, suggesting a remarkable cancellation among the instanton effects in these theories. Here, we show that this cancellation follows directly from a residue theorem, whose proof relies only upon the right-moving world-sheet supersymmetries and suitable compactness properties of the (0,2) linear sigma model. Our residue theorem also extends to a new class of "half-linear" sigma models. Using these half-linear models, we show that heterotic compactifications on the quintic hypersurface in CP^4 for which the gauge bundle pulls back from a bundle on CP^4 are stable. Finally, we apply similar ideas to compute the superpotential contributions from families of membrane instantons in M-theory compactifications on manifolds of G_2 holonomy.Comment: 47 page

Across the Indian Ocean: a remarkable example of trans-oceanic dispersal in an austral mygalomorph spider [dataset]

The Migidae are a family of austral trapdoor spiders known to show a highly restricted and disjunct distribution pattern. Here, we aim to investigate the phylogeny and historical biogeography of the group, which was previously thought to be vicariant in origin, and examine the biogeographic origins of the genus Moggridgea using a dated multi-gene phylogeny. Moggridgea specimens were sampled from southern Australia and Africa, and Bertmainus was sampled from Western Australia. Sanger sequencing methods were used to generate a robust six marker molecular dataset consisting of the nuclear genes 18S rRNA, 28S rRNA, ITS rRNA, XPNPEP3 and H3 and the mitochondrial gene COI. Bayesian and Maximum Likelihood methods were used to analyse the dataset, and the key dispersal nodes were dated using BEAST. Based on our data, we demonstrate that Moggridgea rainbowi from Kangaroo Island, Australia is a valid member of the otherwise African genus Moggridgea. Molecular clock dating analyses show that the inter-specific divergence of M. rainbowi from African congeners is between 2.27–16.02 million years ago (Mya). This divergence date significantly post-dates the separation of Africa from Gondwana (95 Mya) and therefore does not support a vicariant origin for Australian Moggridgea. It also pre-dates human colonisation of Kangaroo Island, a result which is further supported by the intra-specific divergence date of 1.10–6.39 Mya between separate populations on Kangaroo Island. These analyses provide strong support for the hypothesis that Moggridgea colonised Australia via long-distance trans-Indian Ocean dispersal, representing the first such documented case in a mygalomorph spider

Mechanical and structural assessment of laboratory- and field-compacted asphalt mixtures

Compaction forms an integral part in the formation of the aggregate orientation and structure of an asphalt mixture and therefore has a profound influence on its final volumetric and mechanical performance. This article describes the influence of various forms of laboratory (gyratory, vibratory and slab-roller) and field compaction on the internal structure of asphalt specimens and subsequently on their mechanical properties, particularly stiffness and permanent deformation. A 2D image capturing and image analysis system has been used together with alternative specimen sizes and orientations to quantify the internal aggregate structure (orientation and segregation) for a range of typically used continuously graded asphalt mixtures. The results show that in terms of aggregate orientation, slab-compacted specimens tend to mimic field compaction better than gyratory and vibratory compaction. The mechanical properties of slab-compacted specimens also tend to be closer to that of field cores. However, the results also show that through careful selection of specimen size, specimen orientation and compaction variables, even mould-based compaction methods can be utilised with particular asphalt mixtures to represent field-compacted asphalt mixtures

H110alpha recombination-line emission and 4.8-GHz continuum emission in the Carina Nebula

We present results from observations of H110alpha recombination-line emission at 4.874 GHz and the related 4.8-GHz continuum emission towards the Carina Nebula using the Australia Telescope Compact Array. These data provide information on the velocity, morphology and excitation parameters of the ionized gas associated with the two bright HII regions within the nebula, Car I and Car II. They are consistent with both Car I and Car II being expanding ionization fronts arising from the massive star clusters Trumpler 14 and Trumpler 16, respectively. The overall continuum emission distribution at 4.8 GHz is similar to that at lower frequencies. For Car I, two compact sources are revealed that are likely to be young HII regions associated with triggered star formation. These results provide the first evidence of ongoing star formation in the northern region of the nebula. A close association between Car I and the molecular gas is consistent with a scenario in which Car I is currently carving out a cavity within the northern molecular cloud. The complicated kinematics associated with Car II point to expansion from at least two different centres. All that is left of the molecular cloud in this region are clumps of dense gas and dust which are likely to be responsible for shaping the striking morphology of the Car II components.Comment: 10 pages, 7 figures, accepted for publication in MNRA

Supersymmetric AdS5 black holes

The first examples of supersymmetric, asymptotically AdS5, black hole solutions are presented. They form a 1-parameter family of solutions of minimal five-dimensional gauged supergravity. Their angular momentum can never vanish. The solutions are obtained by a systematic analysis of supersymmetric solutions with Killing horizons. Other new examples of such solutions are obtained. These include solutions for which the horizon is a homogeneous Nil or SL(2,R) manifold.Comment: 31 pages. v2: References and calculation of holographic stress tensor added. v3: Solutions preserve 2 supersymmetries. Our original claim that they preserve 4 supersymmetries was based on Ref. [30], which contains a mistake (the general timelike solution preserves 2, not 4, supersymmetries). Nothing else affecte

Towards a synthesized critique of neoliberal biodiversity conservation

During the last three decades, the arena of biodiversity conservation has largely aligned itself with the globally dominant political ideology of neoliberalism and associated governmentalities. Schemes such as payments for ecological services are promoted to reach the multiple ‘wins’ so desired: improved biodiversity conservation, economic development, (international) cooperation and poverty alleviation, amongst others. While critical scholarship with respect to understanding the linkages between neoliberalism, capitalism and the environment has a long tradition, a synthesized critique of neoliberal conservation - the ideology (and related practices) that the salvation of nature requires capitalist expansion - remains lacking. This paper aims to provide such a critique. We commence with the assertion that there has been a conflation between ‘economics’ and neoliberal ideology in conservation thinking and implementation. As a result, we argue, it becomes easier to distinguish the main problems that neoliberal win-win models pose for biodiversity conservation. These are framed around three points: the stimulation of contradictions; appropriation and misrepresentation and the disciplining of dissent. Inspired by Bruno Latour’s recent ‘compositionist manifesto’, the conclusion outlines some ideas for moving beyond critique