F-theory at order α′3\alpha'^3

We study the effective physics of F-theory at order $\alpha'^3$ in derivative expansion. We show that the ten-dimensional type IIB eight-derivative couplings involving the graviton and the axio-dilaton naturally descend from pure gravity in twelve dimensions. Upon compactification on elliptically fibered Calabi-Yau fourfolds, the non-trivial vacuum profile for the axio-dilaton leads to a new, genuinely N=1, $\alpha'^3$ correction to the four-dimensional effective action.Comment: 24 pages, minor improvements, typos correcte

The effective action of warped M-theory reductions with higher-derivative terms - Part II

We study the three-dimensional effective action obtained by reducing eleven-dimensional supergravity with higher-derivative terms on a background solution including a warp-factor, an eight-dimensional compact manifold, and fluxes. The dynamical fields are K\"ahler deformations and vectors from the M-theory three-form. We show that the potential is only induced by fluxes and the naive contributions obtained from higher-curvature terms on a Calabi-Yau background vanish once the back-reaction to the full solution is taken into account. For the resulting three-dimensional action we analyse the K\"ahler potential and complex coordinates and show compatibility with N=2 supersymmetry. We argue that the higher-order result is also compatible with a no-scale condition. We find that the complex coordinates should be formulated as divisor integrals for which a non-trivial interplay between the warp-factor terms and the higher-curvature terms allow a derivation of the moduli space metric. This leads us to discuss higher-derivative corrections to the M5-brane action.Comment: 26 page

Non-Supersymmetric F-Theory Compactifications on Spin(7) Manifolds

We propose a novel approach to obtain non-supersymmetric four-dimensional effective actions by considering F-theory on manifolds with special holonomy Spin(7). To perform such studies we suggest that a duality relating M-theory on a certain class of Spin(7) manifolds with F-theory on the same manifolds times an interval exists. The Spin(7) geometries under consideration are constructed as quotients of elliptically fibered Calabi-Yau fourfolds by an anti-holomorphic and isometric involution. The three-dimensional minimally supersymmetric effective action of M-theory on a general Spin(7) manifold with fluxes is determined and specialized to the aforementioned geometries. This effective theory is compared with an interval Kaluza-Klein reduction of a non-supersymmetric four-dimensional theory with definite boundary conditions for all fields. Using this strategy a minimal set of couplings of the four-dimensional low-energy effective actions is obtained in terms of the Spin(7) geometric data. We also discuss briefly the string interpretation in the Type IIB weak coupling limit.Comment: 39 pages, 4 figures, v2: improvements and clarifications on the 4d interpretation and weak coupling limit; typos correcte

On M-theory fourfold vacua with higher curvature terms

We study solutions to the eleven-dimensional supergravity action, including terms quartic and cubic in the Riemann curvature, that admit an eight-dimensional compact space. The internal background is found to be a conformally Kahler manifold with vanishing first Chern class. The metric solution, however, is non-Ricci-flat even when allowing for a conformal rescaling including the warp factor. This deviation is due to the possible non-harmonicity of the third Chern-form in the leading order Ricci-flat metric. We present a systematic derivation of the background solution by solving the Killing spinor conditions including higher curvature terms. These are translated into first-order differential equations for a globally defined real two-form and complex four-form on the fourfold. We comment on the supersymmetry properties of the described solutions.Comment: 14 page

F-Theory on Spin(7) Manifolds: Weak-Coupling Limit

F-theory on appropriately fibered Spin(7) holonomy manifolds is defined to arise as the dual of M-theory on the same space in the limit of a shrinking fiber. A class of Spin(7) orbifolds can be constructed as quotients of elliptically fibered Calabi-Yau fourfolds by an anti-holomorphic involution. The F-theory dual then exhibits one macroscopic dimension that has the topology of an interval. In this work we study the weak-coupling limit of a subclass of such constructions and identify the objects that arise in this limit. On the Type IIB side we find space-time filling O7-planes as well as O5-planes and orbifold five-planes with a (-1)^{F_L} factor localised on the interval boundaries. These orbifold planes are referred to as X5-planes and are S-dual to a D5-O5 system. For other involutions exotic O3-planes and X3-planes on top of a six-dimensional orbifold singularity can appear. We show that the objects present preserve a mutual supersymmetry of four supercharges in the bulk of the interval and two supercharges on the boundary. It follows that in the infinite-interval and weak-coupling limit full four-dimensional N=1 supersymmetry is restored, which on the Type IIA side corresponds to an enhancement of supersymmetry by winding modes in the vanishing interval limit.Comment: 23 page

The supermultiplet of boundary conditions in supergravity

Boundary conditions in supergravity on a manifold with boundary relate the bulk gravitino to the boundary supercurrent, and the normal derivative of the bulk metric to the boundary energy-momentum tensor. In the 3D N=1 setting, we show that these boundary conditions can be stated in a manifestly supersymmetric form. We identify the Extrinsic Curvature Tensor Multiplet, and show that boundary conditions set it equal to (a conjugate of) the boundary supercurrent multiplet. Extension of our results to higher-dimensional models (including the Randall-Sundrum and Horava-Witten scenarios) is discussed.Comment: 22 pages. JHEP format; references added; published versio

Exercise training reduces the acute physiological severity of post-menopausal hot flushes.

A hot-flush is characterised by feelings of intense heat, profuse elevations in cutaneous vasodilation and sweating, and reduced brain blood flow. Exercise training reduces self-reported hot-flush severity, but underpinning physiological data are lacking. We hypothesised that exercise training attenuates the changes in cutaneous vasodilation, sweat rate and cerebral blood flow during a hot flush. In a preference trial, 18 symptomatic post-menopausal women underwent a passive heat stress to induce hot-flushes at baseline and follow-up. Fourteen participants opted for a 16-week moderate intensity supervised exercise intervention, while 7 participants opted for control. Sweat rate, cutaneous vasodilation, blood pressure, heart rate and middle cerebral artery velocity (MCAv) were measured during the hot-flushes. Data were binned into eight equal segments, each representing 12.5% of hot flush duration. Weekly self-reported frequency and severity of hot flushes were also recorded at baseline and follow-up. Following training, mean hot-flush sweat rate decreased by 0.04 mg·cm2 ·min-1 at the chest (95% CI: 0.02-0.06, P = 0.01) and by 0.03 mg·cm2 ·min-1 (0.02-0.05, P = 0.03) at the forearm, compared with negligible changes in control. Training also mediated reductions in cutaneous vasodilation by 9% (6-12) at the chest and by 7% (4-9) at forearm (P≤0.05). Training attenuated hot flush MCAv by 3.4 cm/s (0.7-5.1, P = 0.04) compared with negligible changes in control. Exercise training reduced the self-reported severity of hot-flush by 109 arbitrary units (80-121, P<0.001). These data indicate that exercise training leads to parallel reductions in hot-flush severity and within-flush changes in cutaneous vasodilation, sweating and cerebral blood flo

Meeting the expectation of industry: an integrated approach for the teaching of mechanics and electronics to design students

This is an Accepted Manuscript of an article published by Taylor & Francis in European Journal of Engineering Education on 19th January 2015, available online: http://dx.doi.org/10.1080/03043797.2014.1001813This paper examines the traditional engineering-based provision delivered to Product Design and Technology (B.Sc.) undergraduates at the Loughborough Design School and questions its relevancy against the increasing expectations of industry. The paper reviews final-year design projects to understand the level of transference of engineering-based knowledge into design practice and highlights areas of opportunity for improved teaching and learning. The paper discusses the development and implementation of an integrated approach to the teaching of Mechanics and Electronics to formalise and reinforce the key learning process of transference within the design context. The paper concludes with observations from the delivery of this integrated teaching and offers insights from student and academic perspectives for the further improvement of engineering-based teaching and learning