Book review: a tale of two books: digital transformations are creeping across the face of academic life

In response to Patrick Dunleavy’s posts on the future of e-publishing in academia, David Gauntlett writes on his experiences of publishing ebooks, and how Kindle self-publishing could be an approach which gets books to readers at a far more affordable price, as well as being surprisingly better for authors too

Bubbling 1/2 BPS solutions of minimal six-dimensional supergravity

We continue our previous analysis (hep-th/0412045) of 1/2 BPS solutions to minimal 6d supergravity of bubbling form. We show that, by turning on an axion field in the T^2 torus reduction, the constraint F \wedge F, present in the case of an S^1 x S^1 reduction, is relaxed. We prove that the four-dimensional reduction to a bosonic field theory, whose content is the metric, a gauge field, two scalars and a pseudo-scalar (the axion), is consistent. Moreover, these reductions when lifted to the six-dimensional minimal supergravity represent the sought-after family of 1/2 BPS bubbling solutions.Comment: 17 pages, late

Geometries with Killing Spinors and Supersymmetric AdS Solutions

The seven and nine dimensional geometries associated with certain classes of supersymmetric $AdS_3$ and $AdS_2$ solutions of type IIB and D=11 supergravity, respectively, have many similarities with Sasaki-Einstein geometry. We further elucidate their properties and also generalise them to higher odd dimensions by introducing a new class of complex geometries in $2n+2$ dimensions, specified by a Riemannian metric, a scalar field and a closed three-form, which admit a particular kind of Killing spinor. In particular, for $n\ge 3$, we show that when the geometry in $2n+2$ dimensions is a cone we obtain a class of geometries in $2n+1$ dimensions, specified by a Riemannian metric, a scalar field and a closed two-form, which includes the seven and nine-dimensional geometries mentioned above when $n=3,4$, respectively. We also consider various ansatz for the geometries and construct infinite classes of explicit examples for all $n$.Comment: 28 page

A Dielectric Flow Solution with Maximal Supersymmetry

We obtain a solution to eleven-dimensional supergravity that consists of M2-branes embedded in a dielectric distribution of M5-branes. Contrary to normal expectations, this solution has maximal supersymmetry for a brane solution (i.e. sixteen supercharges). While the solution is constructed using gauged supergravity in four dimensions, the complete eleven-dimensional solution is given. In particular, we obtain the Killing spinors explicitly, and we find that they are characterised by a duality rotation of the standard Dirichlet projection matrix for M2-branes.Comment: 17 pages; harvma

The Costs and Benefits of Effluent Management Compliance in the Waikato Region of New Zealand

Dairy farming in the Waikato Region has contributed greatly to the reduction of water quality. Part of this is attributable to the issue of inappropriate disposal of dairy effluent. Regional authority data shows both costs and benefits of complying with effluent management regulations. Private costs result from system and management improvements, while private benefits are largely due to reduced fertiliser requirements. Decreases in the volume of 'non-compliant effluent', resulting from improved compliance, are used as an indicator to illustrate reduced environmental effects. The benefits of becoming compliant outweigh the costs for half the farms analysed. More incentives are required to promote compliance from the other farms although their environmental effects are generally smaller.Dairy farming, environment, effluent, compliance, cost, benefit.,

Comments on AdS2 solutions of D=11 Supergravity

We study the supersymmetric solutions of 11-dimensional supergravity with a factor of $AdS_2$ made of M2-branes. Such solutions can provide gravity duals of superconformal quantum mechanics, or through double Wick rotation, the generic bubbling geometry of M-theory which are 1/16-BPS. We show that, when the internal manifold is compact, it should take the form of a warped U(1)-fibration over an 8-dimensional Kahler space.Comment: 11 pages, no figure, JHEP3.cl

Generalizing the N=2 supersymmetric RG flow solution of IIB supergravity

We explicitly construct the supersymmetry transformations for the N=2 supersymmetric RG flow solution of chiral IIB supergravity. We show that the metric, dilaton/axion, five-index tensor and half of the three index tensor are determined algebraically in terms of the Killing spinor of the unbroken supersymmetry. The algebraic nature of the solution allows us to generalize this construction to a new class of N=2 supersymmetric solutions of IIB supergravity. Each solution in this class is algebraically determined by supersymmetry and is parametrized by a single function of two variables that satisfies a non-linear equation akin to the Laplace equation on the space transverse to the brane.Comment: 27 pages; harvmac; tex twic