A three-dimensional Gaussian-beam ray-tracing program for designing interferometer/polarimeter plasma diagnostics

We have developed a three-dimensional Gaussian-beam ray-tracing program to aid in the design of infrared, far-infrared, and millimeter waveinterferometer and polarimeterdiagnostic systems for magnetic confinementfusion relevant plasma physicsexperiments. An overview of the program is presented along with a description of the ray-tracing algorithm. A model is developed for the case of diffraction of a Gaussian beam off a cylindrical grating and is shown to be in good agreement with experimental measurements. The program has been used to aid the design of the scanning-grating interferometer system for the H-1NF heliac experimental plasma device. The program is written in the Research Systems Inc. Interactive Data Language and, on a typical modern personal computer, is able to trace and render the ∼50 element three-view 44-beam H-1NF interferometer optical system in about one minute.This work was in part supported by the Australian Institute of Nuclear Science and Engineering, the Australian Research Council, and the Australian Vice-Chancellors’ Committee Commonwealth Scholarship and Fellowship Plan

The emotional geography of prison life

Accounts of prison life consistently describe a culture of mutual mistrust, fear, aggression and barely submerged violence. Often too, they explain how prisoners adapt to this environment—in men’s prisons, at least—by putting on emotional ‘masks’ or ‘fronts’ of masculine bravado which hide their vulnerabilities and deter the aggression of their peers. This article does not contest the truth of such descriptions, but argues that they provide a partial account of the prison’s emotional world. Most importantly, for current purposes, they fail to describe the way in which prisons have a distinctive kind of emotional geography, with zones in which certain kinds of emotional feelings and displays are more or less acceptable. In this article, we argue that these ‘emotion zones’, which cannot be characterized either as ‘frontstage’ or ‘backstage’ domains, enable the display of a wider range of feelings than elsewhere in the prison. Their existence represents a challenge to depictions of prisons as environments that are unwaveringly sterile, unfailingly aggressive or emotionally undifferentiated. This is the accepted manuscript. The final version is available from Sage at http://tcr.sagepub.com/content/18/1/56

Communications Biophysics

Contains reports on three research projects.National Institutes of Health (Grant MH-04737-05)National Institutes of Health (Grant NB-05462-02)Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 36-039-AMC-03200(E)National Science Foundation (Grant GP-2495)National Aeronautics and Space Administration (Grant NsG-496

Fed-Batch E. coli cultures in a shaken, single-use 24-well miniature bioreactor

At industrial scale, microbial cultivations are usually performed in fed-batch mode to allow for high cell density cost-effective processes. Miniature bioreactors are becoming widely used in the biopharmaceutical industry as a tool for high throughput strain evaluation and fermentation process development. However, there are relatively few examples of miniature bioreactors capable of fed-batch operation and of supporting the high oxygen demand. There are several challenges that need to be addressed to establish high cell density fed-batch cultivation at microscale: attaining high oxygen mass transfer rates, achieving good mixing for the duration of the culture and implementation of an industrially relevant feeding strategy requiring low volume additions. In this work a shaken, single-use 24-well miniature bioreactor (Pall, Micro 24 MicroReactor System) has been characterised in terms of volumetric oxygen mass transfer coefficient (kLa) and liquid phase mixing time (tm) to assess the feasibility of high cell density microbial cultures. The impact of shaking frequency, total gas flow rate and fill volume on oxygen transfer and fluid mixing were investigated and the optimum operating conditions were determined. To enable fed-batch cultivation in the miniature bioreactor system a bespoke feeding system for direct, continuous feed delivery has been developed that works at feed flow rates of 20μL h-1 and above. This feeding system allows for 24 fed-batch cultures to be run in parallel. Within the operating ranges of the miniature bioreactor system, it was found that oxygen transfer was dependant on both shaking frequency and gas flow rate, but was independent of fill volume; the oxygen mass transfer coefficient, kLa increased with both increasing shaking frequency and gas flow rate over the range 3-101h-1. The liquid phase mixing time, tm under non-aerated conditions increased with shaking frequency and decreased with fill volume over the range 0.8-15.3s. It has been demonstrated that the miniature bioreactor system is well mixed under the range of operating conditions evaluated. The bespoke feed delivery system was used to perform fed-batch cultures of an industrial E. coli strain producing an antibody fragment under operating conditions defined from the engineering characterisation studies. Fermentations were performed on a semi-complex medium containing glycerol with direct feeding of a glycerol solution initiated around 15 hours. It was found that direct feeding enhances biomass production by 30-40% and product expression by 45-65% in comparison to non-fed cultures. The feeding system developed in this work allows for industrially relevant microbial processes to be implemented at the microscale

Velocity correlations in dense granular gases

We report the statistical properties of spherical steel particles rolling on an inclined surface being driven by an oscillating wall. Strong dissipation occurs due to collisions between the particles and rolling and can be tuned by changing the number density. The velocities of the particles are observed to be correlated over large distances comparable to the system size. The distribution of velocities deviates strongly from a Gaussian. The degree of the deviation, as measured by the kurtosis of the distribution, is observed to be as much as four times the value corresponding to a Gaussian, signaling a significant breakdown of the assumption of negligible velocity correlations in a granular system.Comment: 4 pages, 4 Figure

Flow Equations for N Point Functions and Bound States

We discuss the exact renormalization group or flow equation for the effective action and its decomposition into one particle irreducible N point functions. With the help of a truncated flow equation for the four point function we study the bound state problem for scalar fields. A combination of analytic and numerical methods is proposed, which is applied to the Wick-Cutkosky model and a QCD-motivated interaction. We present results for the bound state masses and the Bethe-Salpeter wave function. (Figs. 1-4 attached as separate uuencoded post-script files.)Comment: 17 pages, HD-THEP-93-3

Do divorcing couples become happier by breaking up?

Divorce is a leap in the dark. The paper investigates whether people who split up actually become happier. Using the British Household Panel Survey, we can observe an individual's level of psychological well-being in the years before and after divorce. Our results show that divorcing couples reap psychological gains from the dissolution of their marriages. Men and women benefit equally. The paper also studies the effects of bereavement, of having dependant children and of remarriage. We measure well-being by using general health questionnaire and life satisfaction scores