so this nuthatch

Poetry by Robie Liscomb

Reentrant phase transitions and van der Waals behaviour for hairy black holes

We study the extended phase space thermodynamics for hairy AdS black hole solutions to Einstein-Maxwell-$\Lambda$ theory conformally coupled to a scalar field in five dimensions. We find these solutions to exhibit van der Waals behaviour in both the charged/uncharged cases, and reentrant phase transitions in the charged case. This is the first example of reentrant phase transitions in a five dimensional gravitational system which does not include higher curvature corrections.Comment: 11 pages, 5 figures, REVTeX 4-

Criticality for charged black branes

We show that the inclusion of higher curvature terms in the gravitational action can lead to phase transitions and critical behaviour for charged black branes. The higher curvature terms considered here belong to the recently constructed generalized quasi-topological class [ArXiv: 1703.01631], which possess a number of interesting properties, such as being ghost-free on constant curvature backgrounds and non-trivial in four dimensions. We show that critical behaviour is a generic feature of the black branes in all dimensions $d \ge 4$, and contextualize the results with a review of the properties of black branes in Lovelock and quasi-topological gravity, where critical behaviour is not possible. These results may have interesting implications for the CFTs dual to this class of theories.Comment: 31 pages, 6 figures. v2: minor typos corrected, references added; updated to match published versio

Thermalon mediated phase transitions in Gauss-Bonnet gravity

Thermalons can mediate phase transitions between different vacua in higher curvature gravity, potentially changing the asymptotic structure of the spacetime. Treating the cosmological constant as a dynamical parameter, we study these phase transitions in the context of extended thermodynamic phase space. We find that in addition to the AdS to dS phase transitions previously studied, thermal AdS space can undergo a phase transition to an asymptotically flat black hole geometry. In the context of AdS to AdS transitions, we comment on the similarities and differences between thermalon transitions and the Hawking-Page transition.Comment: 20 pages, 11 figures; reference added, corrected to match published versio

The metabolism of the Antartic crytoendolithic microbiota

The carbon metabolism of the cryptoendolithic microbiota in sandstones from the Ross Desert region of Antarctica was studied in situ and in vitro. Organic and inorganic compounds were metabolized by the microbiota, with bicarbonate being metabolized maximally in the light. There was a linear response of photosynthesis to light up to 200 to 300 micromole photons/sq m/s. The community photosynthetic response to temperature was a minimum at -5 C, two optima at +5 and +15 C and a maximum at +35 C. Photosynthetic metabolism occurred maximally in the presence of liquid water, but could occur in an environment of water vapor. Biomass of the cryptoendolithic microbiota was measured as the amount of lipid phosphate present. The in situ biomass ranged from 1.92 to 3.26 g carbon/sq m of rock and 2 orders of magnitude less than epilithic lichen microbiota from Antarctica in a location 7 degrees more north in latitude. With these data, it was possible to calculate primary production and carbon turnover in this simple microbiota. Production values ranged from 0.108 to 4.41 mg carbon/sq m/yr, while carbon turnover values ranged from 576 to 23,520 years. These values are the lowest and longest yet recorded for any ecosystem on Earth. If life did evolve on Mars to the level of prokaryotes or primitive eukaryotes, the possibility that the organisms retreated, to the protection of the inside of the rock so that metabolism could continue during planetary cooling, cannot be overlooked

Diversity reportage in Aotearoa: demographics and the rise of the ethnic media

For more than two decades, diversity has been a growing mantra for the New Zealand news media. Initially, the concept of biculturalism-partnership with the indigenous tangata whenua-was pre-eminent in the debate, but as the nation's Pasifika and ethnic media have flourished and matured and demographics have rapidly changed, multiculturalism has become increasingly important and challenging. The regional media relationship in the context of contested notions such as the 'arc of instability' and the impact of coups and crises on journalists has become critical. Projected demographics by Statistics New Zealand indicate that the country's Asian population will almost double by 2026. The Pasifika and Maori populations are also expected to grow by 59 and 29 per cent respectively. Maori, Pasifika and ethnic media in Aotearoa/New Zealand are also steadily expanding with implications for the media industry and journalism educators. This article examines the regional trends and how initiatives such as the Pacific Media Centre and new journalism courses with an emphasis on diversity are addressing the challenges

P-V Criticality in Quasitopological Gravity

We investigate the thermodynamic behaviour of AdS quasitopological black hole solutions in the context of extended thermodynamic phase space, in which the cosmological constant induces a pressure with a conjugate volume. We find that the third order exact quasitopological solution exhibits features consistent with the third order Lovelock solutions for positive quasitopological coupling, including multiple reentrant phase transitions and isolated critical points. For negative coupling we find the first instances of both reentrant phase transitions and thermodynamic singularities in five dimensions, along with other modified thermodynamic behaviour compared to Einstein-AdS-Gauss Bonnet gravity.Comment: 20 pages, 15 figures, REVTeX 4-1; updated to match published versio

Ultraspinning limits and super-entropic black holes

By employing the new ultraspinning limit we construct novel classes of black holes with non-compact event horizons and finite horizon area and study their thermodynamics. Our ultraspinning limit can be understood as a simple generating technique that consists of three steps: i) transforming the known rotating AdS black hole solution to a special coordinate system that rotates (in a given 2-plane) at infinity ii) boosting this rotation to the speed of light iii) compactifying the corresponding azimuthal direction. In so doing we qualitatively change the structure of the spacetime since it is no longer possible to return to a frame that does not rotate at infinity. The obtained black holes have non-compact horizons with topology of a sphere with two punctures. The entropy of some of these exceeds the maximal bound implied by the reverse isoperimetric inequality, such black holes are super-entropic.Comment: 19 pages, 6 figures; minor corrections as in published version, updated reference

Quintessential Quartic Quasi-topological Quartet

We construct the quartic version of generalized quasi-topological gravity, which was recently constructed to cubic order in arXiv: 1703.01631. This class of theories includes Lovelock gravity and a known form of quartic quasi-topological gravity as special cases and possess a number of remarkable properties: (i) In vacuum, or in the presence of suitable matter, there is a single independent field equation which is a total derivative. (ii) At the linearized level, the equations of motion on a maximally symmetric background are second order, coinciding with the linearized Einstein equations up to a redefinition of Newton's constant. Therefore, these theories propagate only the massless, transverse graviton on a maximally symmetric background. (iii) While the Lovelock and quasi-topological terms are trivial in four dimensions, there exist four new generalized quasi-topological terms (the quartet) that are nontrivial, leading to interesting higher curvature theories in $d \geq 4$ dimensions that appear well suited for holographic study. We construct four dimensional black hole solutions to the theory and study their properties. A study of black brane solutions in arbitrary dimensions reveals that these solutions are modified from the `universal' properties these solutions have. This result may lead to interesting consequences for the dual CFTs.Comment: 46 pages, 1 figure. Discussion of black branes added to section