Passive tracers in a general circulation model of the Southern Ocean

Passive tracers are used in an o?-line version of the United Kingdom Fine Resolution Antarctic Model (FRAM) to highlight features of the circulation and provide information on the inter-ocean exchange of water masses. The use of passive tracers allows a picture to be built up of the deep circulation which is not readily apparent from examination of the velocity or density ®elds. Comparison of observations with FRAM results gives good agreement for many features of the Southern Ocean circulation. Tracer distributions are consistent with the concept of a global ``conveyor belt'' with a return path via the Agulhas retro¯ection region for the replenishment of North Atlantic Deep Water

Survival of the ideas that fit: An evolutionary analogy for the use of evidence in policy

This paper explores bias in the use of evidence in policy. It argues that existing models of the evidence–policy relationship neglect the tendency for attention to be paid only to that evidence helpful to the interests of powerful social groups. An evolutionary analogy is used to explain how this bias arises, without the need for irrationality or conspiracy on the part of policy makers. Examples are given in the fields of drug, asylum and other policies, and the possible responses by researchers to the biased use of research evidence are discussed

The dominant X-ray wind in massive star binaries

We investigate which shocked wind is responsible for the majority of the X-ray emission in colliding wind binaries, an issue where there is some confusion in the literature, and which we show is more complicated than has been assumed. We find that where both winds rapidly cool (typically close binaries), the ratio of the wind speeds is often more important than the momentum ratio, because it controls the energy flux ratio, and the faster wind is generally the dominant emitter. When both winds are largely adiabatic (typically long-period binaries), the slower and denser wind will cool faster and the stronger wind generally dominates the X-ray luminosity.Comment: 4 pages, 1 figure, accepted by A&A Letter

On open boundary conditions for three dimensional primitive equation ocean circulation models

An open boundary condition is constructed for three dimensional primitive equation ocean circulation models. The boundary condition utilises dominant balances in the governing equations to assist calculations of variables at the boundary. The boundary condition can be used in two forms. Firstly as a passive one in which there is no forcing at the boundary and phenomena generated within the domain of interest can propagate outwards without distorting the interior. Secondly as an active condition where a model is forced by the boundary condition. Three simple idealised tests are performed to verify the open boundary condition, (1) a passive condition to test the outflow of free Kelvin waves, (2) an active condition during the spin up phase of an ocean, (3) finally an example of the use of the condition in a tropical ocean

Deforming nonnormal isolated surface singularities and constructing 3-folds with P1\mathbb{P}^1 as exceptional set

Normally one assumes isolated surface singularities to be normal. The purpose of this paper is to show that it can be useful to look at nonnormal singularities. By deforming them interesting normal singularities can be constructed, such as isolated, non Cohen-Macaulay threefold singularities. They arise by a small contraction of a smooth rational curve, whose normal bundle has a sufficiently positive subbundle. We study such singularities from their nonnormal general hyperplane section.Comment: 20