Energy in Yang-Mills on a Riemann Surface

Sengupta's lower bound for the Yang-Mills action on smooth connections on a bundle over a Riemann surface generalizes to the space of connections whose action is finite. In this larger space the inequality can always be saturated. The Yang-Mills critical sets correspond to critical sets of the energy action on a space of paths. This may shed light on Atiyah and Bott's conjecture concerning Morse theory for the space of connections modulo gauge transformations.Comment: 7 pages, 2 figures, Latex2e with epsfig, submitted to Journal of Mathematical Physic

A Note on the Equality of Algebraic and Geometric D-Brane Charges in WZW Models

The algebraic definition of charges for symmetry-preserving D-branes in Wess-Zumino-Witten models is shown to coincide with the geometric definition, for all simple Lie groups. The charge group for such branes is computed from the ambiguities inherent in the geometric definition.Comment: 12 pages, fixed typos, added references and a couple of remark

Biocide Dosing Strategies for Biofilm Control

In order to reduce environmental impact of biocide use for the control of biofilm formation in cooling water circuits, “environmentally friendly” biocides have been developed, but they are generally more expensive than the more traditional chemicals. It is imperative therefore, that the minimum quantity of biocide is employed, so that costs are kept to a minimum. To achieve this objective optimum dosing strategies are required. Using apilot plant in conjunction with a monoculture of Pseudomonas fluorecsens as the biofouling bacterium, tests were carried out using a proprietary biocide, to investigate the effects of dose concentration, duration and frequency of dosing and fluid mechanics on biofilm control. With four 15 minute applications per day, at a peak concentration of 16.8 mg/l, it was not possible to inhibit biofilm development. Control was effected however, by doubling the peak concentration using a short dosing period. Concentration, as would be expected, was shown to be a critical factor for control. A boicide concentration below that for growth inhibition, seemed to enhance biofilm formation! Increase frequency of dosing is only effective if the concentration employed is biofilm growth inhibiting

Nutritional and smoking advice recalled by patients attending a UK age-related macular degeneration clinic

Background: Age-related macular degeneration (AMD) is responsible for half of registered visual impairment in the UK. The Royal College of Ophthalmologists recommends providing guidance to people with AMD regarding smoking, diet, and nutritional supplements. The aim of this study was to investigate lifestyle advice recalled by patients with neovascular AMD (nAMD). Methods: The study took place at a UK hospital outpatients' clinic. Eligible patients with unilateral nAMD were presented with a survey about lifestyle advice provision. Results: Of 248 respondents, only 39.9% remembered receiving advice regarding diet at the hospital. Only 24.2% of respondents recalled receiving advice regarding nutritional supplements, and only 19.8% of respondents started taking daily supplements as a result of their AMD. The most prevalent reason for not taking supplements amongst those advised to do so was lack of understanding of how it would help their eyes. Nearly 13% of the sample reported currently smoking, 53.1% of which reported that they were advised to stop smoking when diagnosed with AMD. Conclusion: The findings suggest that it would be beneficial to review the provision of lifestyle advice to patients attending AMD outpatients' clinics, and to consider whether advice is being provided in an optimal format for later recall

Representations of p-brane topological charge algebras

The known extended algebras associated with p-branes are shown to be generated as topological charge algebras of the standard p-brane actions. A representation of the charges in terms of superspace forms is constructed. The charges are shown to be the same in standard/extended superspace formulations of the action.Comment: 22 pages. Typos fixed, refs added. Minor additions to comments sectio

A New Symmetry for QED

We demonstrate that QED exhibits a previously unobserved symmetry. Some consequences are discussed.Comment: 9 pages, MZ-TH/93-02, DIAS-STP-93-0

Separation by thermal diffusion in a rotary column

A rotary thermal diffusion column with the inner cylinder rotating and the outer cylinder static was used to separate n-heptane-benzene mixtures at different speeds of rotation. The results show that the column efficiency depends on the speed of rotation. For the optimum speed the increase in efficiency relative to the static column was of the order of 8%. The role of the geometric irregularities in the annulus width on performance of the rotary column is also discussed.Calouste Gulbenkian Foundatio

Liquid thermal diffusion in a batch rotary column

Experimental observations of separation by thermal diffusion in rotary columns have been published, but no adequate theory to explain the column performance has been given. By consideration of the hydrodynamics within the annular space an approximate theory has been developed which shows that for a geometrically perfect column the relevant parameters affecting separation can be simply related to the corresponding static column. The relaxation-time and separation are virtually independent of the speed of rotation and separation values are more favourable for the rotary column. The application of the theory to non-perfect practical columns requires the consideration of the "equivalent annulus width" concept similar to the static case. Experimental tests conducted at different speeds of rotation in two geometrically different columns whose inner cylinder rotates and the outer is static, showed that the rotation at moderate speeds increased the equilibrium separation by about 7%, reducing, simultaneously the relaxation time by an average of 3%. These results are in good agreement with the theoretical predictions

Proton imaging of stochastic magnetic fields

Recent laser-plasma experiments report the existence of dynamically significant magnetic fields, whose statistical characterisation is essential for understanding the physical processes these experiments are attempting to investigate. In this paper, we show how a proton imaging diagnostic can be used to determine a range of relevant magnetic field statistics, including the magnetic-energy spectrum. To achieve this goal, we explore the properties of an analytic relation between a stochastic magnetic field and the image-flux distribution created upon imaging that field. We conclude that features of the beam's final image-flux distribution often display a universal character determined by a single, field-scale dependent parameter - the contrast parameter - which quantifies the relative size of the correlation length of the stochastic field, proton displacements due to magnetic deflections, and the image magnification. For stochastic magnetic fields, we establish the existence of four contrast regimes - linear, nonlinear injective, caustic and diffusive - under which proton-flux images relate to their parent fields in a qualitatively distinct manner. As a consequence, it is demonstrated that in the linear or nonlinear injective regimes, the path-integrated magnetic field experienced by the beam can be extracted uniquely, as can the magnetic-energy spectrum under a further statistical assumption of isotropy. This is no longer the case in the caustic or diffusive regimes. We also discuss complications to the contrast-regime characterisation arising for inhomogeneous, multi-scale stochastic fields, as well as limitations currently placed by experimental capabilities on extracting magnetic field statistics. The results presented in this paper provide a comprehensive description of proton images of stochastic magnetic fields, with applications for improved analysis of given proton-flux images.Comment: Main paper pp. 1-29; appendices pp. 30-84. 24 figures, 2 table