Deformations of calibrated subbundles of Euclidean spaces via twisting by special sections

We extend the "bundle constructions" of calibrated submanifolds, due to Harvey--Lawson in the special Lagrangian case, and to Ionel--Karigiannis--Min-Oo in the cases of exceptional calibrations, by "twisting" the bundles by a special (harmonic, holomorphic, parallel) section of a complementary bundle. The existence of such deformations shows that the moduli space of calibrated deformations of these "calibrated subbundles" includes deformations which destroy the linear structure of the fibre.Comment: 16 pages, no figures. Version 2: Only minor cosmetic and typographical revisions. To appear in "Annals of Global Analysis and Geometry.

Localized modes at a D-brane--O-plane intersection and heterotic Alice strings

We study a system of $N_c$ $D3$-branes intersecting $D7$-branes and $O7$-planes in 1+1-dimensions. We use anomaly cancellation and string dualities to argue that there must be chiral fermion zero-modes on the $D3$-branes which are localized near the $O7$-planes. Away from the orientifold limit we verify this by using index theory as well as explicit construction of the zero-modes. This system is related to F-theory on K3 and heterotic matrix string theory, and the heterotic strings are related to Alice string defects in $\mathcal{N}=4$ Super-Yang-Mills. In the limit of large $N_c$ we find an $AdS_3$ dual of the heterotic matrix string CFT.Comment: 44 pages, typos corrected, version published in JHE

Anisotropic intrinsic lattice thermal conductivity of phosphorene from first principles

Phosphorene, the single layer counterpart of black phosphorus, is a novel two-dimensional semiconductor with high carrier mobility and a large fundamental direct band gap, which has attracted tremendous interest recently. Its potential applications in nano-electronics and thermoelectrics call for a fundamental study of the phonon transport. Here, we calculate the intrinsic lattice thermal conductivity of phosphorene by solving the phonon Boltzmann transport equation (BTE) based on first-principles calculations. The thermal conductivity of phosphorene at $300\,\mathrm{K}$ is $30.15\,\mathrm{Wm^{-1}K^{-1}}$ (zigzag) and $13.65\,\mathrm{Wm^{-1}K^{-1}}$ (armchair), showing an obvious anisotropy along different directions. The calculated thermal conductivity fits perfectly to the inverse relation with temperature when the temperature is higher than Debye temperature ($\Theta_D = 278.66\,\mathrm{K}$). In comparison to graphene, the minor contribution around $5\%$ of the ZA mode is responsible for the low thermal conductivity of phosphorene. In addition, the representative mean free path (MFP), a critical size for phonon transport, is also obtained.Comment: 5 pages and 6 figures, Supplemental Material available as http://www.rsc.org/suppdata/cp/c4/c4cp04858j/c4cp04858j1.pd

Deformed Matrix Theories with N=8 and Fivebranes in the PP Wave Background

M(atrix) theory is known to be mass-deformed in the pp-wave background and still retains all 16 dynamical supersymmetries. We consider generalization of such deformations on super Yang-Mills quantum mechanics (SYQM) with less supersymmetry. In particular this includes N=8 U(N) SYQM with a single adjoint and any number of fundamental hypermultiplets, which is a pp-wave deformation of DLCQ matrix theory of fivebranes. With k >= 1 fivebranes, we show that a rich vacuum structure exists, with many continuous family of solutions that preserve all dynamical supersymmetries. The vacuum moduli space contains copies of CP^{k-1} of various sizes.Comment: latex file, 23 pages, no figures, typos corrected, now in JHEP styl

A Class of Topological Actions

We review definitions of generalized parallel transports in terms of Cheeger-Simons differential characters. Integration formulae are given in terms of Deligne-Beilinson cohomology classes. These representations of parallel transport can be extended to situations involving distributions as is appropriate in the context of quantized fields.Comment: 41 pages, no figure

Coastal agricultural landscapes: Mapping and understanding grazing intensity on Welsh saltmarshes

Coastal wetlands such as saltmarshes support local communities and industries through ecosystem services and benefit the well-being of local communities in many regions of the world. Along sheltered temperate and sub-tropical coastlines, saltmarshes provide coastal protection, provision of recreational space and wildlife habitat. Those in northwest Europe provide a valuable resource for local agricultural communities through livestock grazing. Following the departure of the UK from the EU and the related potential changes to agricultural policies and markets, it is timely to evaluate the status of saltmarsh livestock grazing. In particular, knowledge of grazing patterns, policy futures and stakeholder perceptions are required to support traditional cultural practice and the ecological status of saltmarshes. This study focuses on the devolved UK nation of Wales, as it has a strong traditional agricultural and pastoral economy, and a landscape of significant conservation value. Yet there are substantial evidence and knowledge gaps regarding livestock grazing and its saltmarsh impact. We present the first map showing the spatial distribution of saltmarsh grazing practice in the UK. Drawing on insights gathered through an expert workshop and interviews with saltmarsh landowners and managers across Wales (N = 35), the paper discusses the challenges and benefits of coastal grazing on saltmarshes, highlighting the diverse values, personal connection and sense of identity associated with marshes. Interviews reveal deep rooted social and cultural values attributed to saltmarshes by the rural coastal community. The study illustrates the need for an integrated approach to management of saltmarshes, accounting for the social, cultural, economic, and environmental values within decision-making

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

A non-contacting resistivity imaging method for characterizing whole round core while in its liner

Recent laboratory experimentation has shown that non-contacting whole-core resistivity imaging, with azimuthal discrimination, is feasible. It has shown the need for very sensitive coil pairs in order to provide resistivity measurements at the desired resolution. Independent high-resolution 'galvanic' resistivity estimations show the 'non-contacting' measurements to be directly proportional to the resistivity of core samples. The response of the technique to a variety of synthetic 'structures' is presented. A whole-core image of a dipping layer is used to demonstrate the three dimensional response of the technique and to show that the resolution of the measurements is of the order of 10mm. Experiments are described which show that the technique is capable of investigating to different depths within the whole round core. The results agree with theoretical predictions and indicate that the technique has the potential to assess invasion near the surface of the core. The technique is intrinsically safe and has the potential to be packaged in a form that would be suitable for whole-core imaging at the well site, or laboratory, without taking core from their liners. Thus it is possible to acquire information crucial for core selection, in addition to acquiring resistivity data at a resolution not too far removed from that of the downhole imaging tools