New tests of the pp-wave correspondence.

The pp-wave/SYM correspondence is an equivalence relation, H string = Δ-J , between the hamiltonian H string of string field theory in the pp-wave background and the dilatation operator Δ in = 4 Super Yang-Mills in the double scaling limit. We calculate matrix elements of these operators in string field theory and in gauge theory. In the string theory Hilbert space we use the natural string basis, and in the gauge theory we use the basis which is isomorphic to it. States in this basis are specific linear combinations of the original BMN operators, and were constructed previously for the case of two scalar impurities. We extend this construction to incorporate BMN operators with vector and mixed impurities. This enables us to verify from the gauge theory perspective two key properties of the three-string interaction vertex of Spradlin and Volovich: (1) the vanishing of the three-string amplitude for string states with one vector and one scalar impurity; and (2) the relative minus sign in the string amplitude involving states with two vector impurities compared to that with two scalar impurities. This implies a spontaneous breaking of the 2 symmetry of the string field theory in the pp-wave background. Furthermore, we calculate the gauge theory matrix elements of Δ-J for states with an arbitrary number of scalar impurities. In all cases we find perfect agreement with the corresponding string amplitudes derived from the three-string vertex

Entropy-driven formation of the gyroid cubic phase

We show, by computer simulation, that tapered or pear-shaped particles, interacting through purely repulsive interactions, can freely self-assemble to form the three-dimensionally periodic, gyroid cubic phase. The Ia3d gyroid cubic phase is formed by these particles both on compression of an isotropic configuration and on expansion of a smectic A bilayer arrangement. For the latter case, it is possible identify the steps by which the topological transformation from non-intersecting planes to fully interpenetrating, periodic networks takes place</p

Social research for a multiethnic population: do the research ethics and standards guidelines of UK Learned Societies address this challenge?

There is increasing recognition in the UK that social science research should generate an evidence base that reflects the ethnic diversity of the population and informs positive developments in public policy and programmes for all. However, describing and understanding ethnic diversity, and associated disadvantage, is far from straightforward. In practice, the ethical and scientific arguments around whether and how to incorporate ethnicity into policy-relevant social research are complex and contentious. In particular, untheorised or insensitive inclusion of data on ethnic 'groups' can have negative consequences. The present investigation begins to explore the extent to which social scientists have access to advice and guidance in this area of research. Specifically, the paper examines how ethnic diversity is explicitly or implicitly considered within the research ethics and scientific standard guidance provided by UK social science Learned Societies to their members. The review found little in the way of explicit attention to ethnic diversity in the guidance documents, but nevertheless identified a number of pertinent themes. The paper compiles and extrapolates these themes to present a tentative set of principles for social scientists to debate and further develop

CO and CI maps of the starburst galaxy M82

The first map of an external galaxy in the 3P₁ - 3P0 fine-structure line of atomic carbon (CI) is presented towards the nucleus of the starbuster M82, and compared with the distinction of the CO J = 4 - 3 molecular emission. The CI traces features that are seen in lower transition CO maps, and shows that CI and the CO are well mixed and have similar spatial distributions. There are small differences between the CO J = 4 - 3 line and lower transition CO data towards the NE part of the molecular ring, where the emission is less prominent. The abundance ratio [CI]/[CO] across M82 is very high, with an average value ~ 0.5 across most of the nucleus, a factor at least 5 times that which is typical of dense molecular cloud cores seen in our own Galaxy. This means that on average, CI is overabundant towards M82. This result can be explained using models which provide enhancements to the CI abundance above normal Interstellar Medium values, a result of a greater cosmic ray flux in M82, or where there is substantial mixing of the gas

A combined GPS/Stated Choice experiment to estimate values of crash-risk reduction

This paper details the development and application of a Stated Choice (SC) experiment designed to explore motorists sensitivities to a kilometre-based charging regime focused around crash-risk reduction. Responses are gathered through a SC experiment that pivots off actual driving behaviour collected over a five week period using an in-vehicle Global Positioning System (GPS) device. This provision of greater reality using revealed preference (RP) information ensures that the alternatives in the SC experiment are embedded in reality, providing motorists with a more realistic context for their choices. The study demonstrates with the improved affordability, power and consumer familiarity with GPS devices, the integration of GPS recorded travel information with SC experiments is a now a feasible solution which can help enrich the quality of the reference alternatives in SC experiments in the future