Many-body theory for positronium-atom interactions

A many-body-theory approach has been developed to study positronium-atom interactions. As first applications, we calculate the elastic scattering and momentum-transfer cross sections and the pickoff annihilation rate $^1Z_\text{eff}$ for Ps collisions with He and Ne. The cross section for He is in agreement with previous coupled-state calculations, and the momentum-transfer cross section for Ne agrees with available experimental data. $^1Z_\text{eff}$ is found to be 0.13 and 0.26 for He and Ne, respectively, in excellent agreement with the measured values.Comment: Accepted by Phys. Rev. Lett. (V2 contains update to text and Figs. 3 and 5. V3 contains further discussion on the calculation of pickoff annihilation rates.

Potentials for hyper-Kahler metrics with torsion

We prove that locally any hyper-K\"ahler metric with torsion admits an HKT potential.Comment: 9 page

Holonomy groups of pseudo-quaternionic-K\"ahlerian manifolds of non-zero scalar curvature

The holonomy group $G$ of a pseudo-quaternionic-K\"ahlerian manifold of signature $(4r,4s)$ with non-zero scalar curvature is contained in \Sp(1)\cdot\Sp(r,s) and it contains \Sp(1). It is proved that either $G$ is irreducible, or $s=r$ and $G$ preserves an isotropic subspace of dimension $4r$, in the last case, there are only two possibilities for the connected component of the identity of such $G$. This gives the classification of possible connected holonomy groups of pseudo-quaternionic-K\"ahlerian manifolds of non-zero scalar curvature.Comment: 7 pages; Dedicated to Dmitri Vladimirovich Alekseevsky at the occasion of his 70th birthda

Effect of composition and density on the ablative performance of phenolic-nylon

Composition and density effects on ablative performance of phenolic-nylo

Closed forms and multi-moment maps

We extend the notion of multi-moment map to geometries defined by closed forms of arbitrary degree. We give fundamental existence and uniqueness results and discuss a number of essential examples, including geometries related to special holonomy. For forms of degree four, multi-moment maps are guaranteed to exist and are unique when the symmetry group is (3,4)-trivial, meaning that the group is connected and the third and fourth Lie algebra Betti numbers vanish. We give a structural description of some classes of (3,4)-trivial algebras and provide a number of examples.Comment: 36 page

An inductive exploration into the flow experiences of European Tour golfers

© 2014 Taylor & Francis. This study explored perceptions regarding the experience of flow in elite golf; a sport which is different to those studied previously due to its self-paced, stop-start nature. In-depth, semi-structured interviews were conducted with 10 European Tour golfers. Whereas the majority of previous studies have deductively coded data into Csikszentmihalyi’s dimensions, the data in this study were analysed inductively. Thirteen categories were generated which described the flow experiences of these golfers, and these were compared with the original flow dimensions after analysis. In contrast to previous understanding, these golfers reported being aware that they were in flow as it occurred, and seemingly were able to manage their flow experiences. A category describing altered cognitive and kinaesthetic perceptions was also generated which was not accounted for in the existing flow framework, while the participants also suggested that flow was observable (e.g. through changes in behaviour). Findings are discussed in relation to the existing literature, and recommendations made for future research including possible revisions to the flow framework to better describe this experience within golf and other sporting contexts

Hippurate: the natural history of a mammalian-microbial co-metabolite

Hippurate, the glycine conjugate of benzoic acid, is a normal constituent of the endogenous urinary metabolite profile and has long been associated with the microbial degradation of certain dietary components, hepatic function and toluene exposure, and is also commonly used as a measure of renal clearance. Here we discuss the potential relevance of hippurate excretion with regards to normal endogenous metabolism and trends in excretion relating to gender, age, and the intestinal microbiota. Additionally, the significance of hippurate excretion with regards to disease states including obesity, diabetes, gastrointestinal diseases, impaired renal function, psychological disorders and autism, as well as toxicity and parasitic infection, are considered