Environmental Influences in SGRs and AXPs

Soft gamma-ray repeaters (SGRs) and anomalous x-ray pulsars (AXPs) are young (<100 kyr), radio-quiet, x-ray pulsars which have been rapidly spun-down to slow spin periods clustered at 5-12 s. Nearly all of these unusual pulsars also appear to be associated with supernova shell remnants (SNRs) with typical ages <20 kyr. If the unusual properties of SGRs and AXPs were due to an innate feature, such as a superstrong magnetic field, then the pre-supernova environments of SGRs and AXPs should be typical of neutron star progenitors. This is not the case, however, as we demonstrate that the interstellar media which surrounded the SGR and AXP progenitors and their SNRs were unusually dense compared to the environments around most young radio pulsars and SNRs. Thus, if these SNR associations are real, the SGRs and AXPs can not be ``magnetars'', and we suggest instead that the environments surrounding SGRs and AXPs play a controlling role in their development.Comment: 5 pages with 2 figures. To appear in the proceedings of the 5th Huntsville GRB Symposium (Huntsville, AL, Oct. 1999

Moving from Data-Constrained to Data-Enabled Research: Experiences and Challenges in Collecting, Validating and Analyzing Large-Scale e-Commerce Data

Widespread e-commerce activity on the Internet has led to new opportunities to collect vast amounts of micro-level market and nonmarket data. In this paper we share our experiences in collecting, validating, storing and analyzing large Internet-based data sets in the area of online auctions, music file sharing and online retailer pricing. We demonstrate how such data can advance knowledge by facilitating sharper and more extensive tests of existing theories and by offering observational underpinnings for the development of new theories. Just as experimental economics pushed the frontiers of economic thought by enabling the testing of numerous theories of economic behavior in the environment of a controlled laboratory, we believe that observing, often over extended periods of time, real-world agents participating in market and nonmarket activity on the Internet can lead us to develop and test a variety of new theories. Internet data gathering is not controlled experimentation. We cannot randomly assign participants to treatments or determine event orderings. Internet data gathering does offer potentially large data sets with repeated observation of individual choices and action. In addition, the automated data collection holds promise for greatly reduced cost per observation. Our methods rely on technological advances in automated data collection agents. Significant challenges remain in developing appropriate sampling techniques integrating data from heterogeneous sources in a variety of formats, constructing generalizable processes and understanding legal constraints. Despite these challenges, the early evidence from those who have harvested and analyzed large amounts of e-commerce data points toward a significant leap in our ability to understand the functioning of electronic commerce.Comment: Published at http://dx.doi.org/10.1214/088342306000000231 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Point vortices on the hyperbolic plane

We investigate some properties of the dynamical system of point vortices on the hyperboloid. This system has noncompact symmetry SL(2, R) and a coadjoint equivariant momentum map J. The relative equilibrium conditions are found and the trajectories of relative equilibria with non-zero momentum value are described. We also provide the classification of relative equilibria and the stability criteria for a number of cases, focusing on N=2, 3. Contrary to the system on the sphere, relative equilibria with non-compact momentum isotropy subgroup are found, and are used to illustrate the different stability types of relative equilibria.Comment: To appear in J. Mathematical Physic

Breakthroughs and discoveries in theatre rehearsals: an ethnographic study of Close Quarters

A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophy.This thesis contributes to the emerging field of rehearsal studies by examining the seldom-analysed (yet oft-referenced) moments of a text based theatre rehearsal where breakthroughs occur that advance the creative process. This thesis presents an original framework through which text-based rehearsal breakthroughs which concentrate primarily on the dynamic between the actor, director and text can be viewed, categorised, and ultimately analysed as ‘The Four Lenses of Breakthrough’. An ethnographic methodology is utilised to analyse data collected from a case study observation of the breakthroughs in the rehearsal period of Kate Bowen’s new play Close Quarters (2018). This thesis sharpens the language used to articulate these moments by creating a practical framework for rehearsal observation and analysis. The Four Lenses created are: (1) individual and small recognition moments that occur; (2) individual discoveries for actors and directors; (3) collective discoveries shared by actors and directors; (4) and, finally, a ‘wow’ moment shared by all, where all the variables coalesce. This thesis builds upon the work of scholars and practitioners whose objective has been to demystify the rehearsal period and to break apart the myth that the rehearsal room is a place of magic, and a mysterious place. With the expansion of rehearsal studies as a field within Western theatre, as well as performance studies since the 1970s, this thesis sits within the critical field of rehearsal studies, and argues for the importance of examining moments of breakthrough in rehearsal. The thesis attests that breakthroughs are unpredictable in a rehearsal period. Even with their ubiquitous occurrence in rehearsals, there is nevertheless a paucity in the literature of explicit analysis of breakthroughs; this thesis also draws together the extant literature as well as offering a new method of analysis

Experimental and numerical studies of whirling fires

Motivation of this study stems from the need to understand the physical mechanisms of whirling fires that occur in an open space and within enclosures. Buoyant whirling flames may be potentially more destructive than ordinary fires due to greater burning rate, higher concentration of heat release in a small region of the plume core, increased radiative output and unexpected smoke movement. The effects of rotation upon the structure and behaviour of buoyant flames have not yet been thoroughly studied and understood. Investigation of this phenomenon is therefore required to allow techniques to be developed that will counter the threat of such outbreaks. Also, the mechanisms controlling the development and stability of whirling flames are of fundamental interest for refined modelling of coherent and self-organised flame behaviour. This work, is an experimental, theoretical and numerical study of whirling fires. Experimental results, a modified CFD model and simulations of whirling flames are presented within this Thesis. The work aims to overcome the limitations of the previous research of whirling fires which is insufficient from both an experimental and theoretical point of view. Firstly, experimental studies of intermediate (room-size) scale whirling fires have not yet been comprehensively reported, despite a great deal of attention devoted to both large scale mass fires and smaller laboratory flames. Experimental studies undertaken using a facility at the Greater Manchester Fire and Rescue Service Training Centre fill this gap, thus demonstrating that whirling flames may develop within a compartment. The periodic precession, formation and destruction of the whirling flame and the increase of the time-averaged burning rate (compared to non-whirling flames in the open space) have been observed. Three fuels with significantly different burning rates (diesel, heptane and ethanol) were investigated in this work. Secondly, previously published results of theoretical analysis of rotating flames were oversimplified and based on strict limitations of the integral model or the inviscid flow assumption. Also there have only been few attempts to undertake CFD modelling of whirling flames. In published studies, radiative heat transfer was not modelled and the burning rate was not coupled with the incident heat flux at the fuel surface. To overcome these limitations, the CFD fire model Fire3D, developed in the Centre for Research in Fire and Explosion Studies, has been adapted to allow numerical simulations of rotating buoyant turbulent diffusion flames. The turbulence model was modified to take into account stabilisation of turbulent fluctuations due to the centrifugal acceleration within the rotating flow. Theoretical analysis of the vorticity equation revealed the physical mechanisms responsible for vorticity concentration and amplification in the rising plume affected by externally imposed circulation. This explains the significant flame elongation (when compared to non-rotating cases) observed in the experiments. Computational results have also been compared to video-recordings of the experimental flames produced; flame elongation was replicated and similar stages of oscillating flame evolution, including formation and destruction of the vortex core, have been identified. Implications of the phenomena studied in relation to fire engineering are also provided. This study contributes to a performance based framework for an engineering approach, which is reliant upon detailed quantitative analysis and modelling. Such an approach is encouraged by modem fire safety legislation including the guides to fire safety engineering BS9999-21 and BS79742 'British Standard 9999-2 Draft Code of Practice for fire safety in the design, construction and use of buildings. BSI, 2004. UK. 2 British Standard BS7974 Application of fire safety engineering principles to the design of buildings. BSI, 2001-2003. UK

Efficacy of buffered sodium citrate alone and in combination with sodium diacetate againstListeria monocytogenes on beef franks

We assessed the antimicrobial efficacy of buffered sodium citrate alone and in combination with sodium diacetate against L. monoyctogenes on beef frank samples stored at 39°F. Initial inoculum level of L. monocytogenes was 1.5 log colony forming units (CFU)/cm2. After 6 weeks of incubation at 39°F, the pathogen reached 5.4 log CFU/cm2 in the control sample, but was 1.2 log CFU/cm2 and 0.85 log CFU/cm2 in samples treated with 1% buffered sodium citrate alone and in combination with 0.1% sodium diacetate, respectively. Use of buffered sodium citrate and the combination of buffered sodium citrate and sodium diacetate should improve safety of ready to eat foods by controlling L. monocytogenes during storage

Cognitive performance in multiple system atrophy

The cognitive performance of a group of patients with multiple system atrophy (MSA) of striato-nigral predominance was compared with that of age and IQ matched control subjects, using three tests sensitive to frontal lobe dysfunction and a battery sensitive to memory and learning deficits in Parkinson's disease and dementia of the Alzheimer type. The MSA group showed significant deficits in all three of the tests previously shown to be sensitive to frontal lobe dysfunction. Thus, a significant proportion of patients from the MSA group failed an attentional set-shifting test, specifically at the stage when an extra-dimensional shift was required. They were also impaired in a subject-ordered test of spatial working memory. The MSA group showed deficits mostly confined to measures of speed of thinking, rather than accuracy, on the Tower of London task. These deficits were seen in the absence of consistent impairments in language or visual perception. Moreover, the MSA group showed no significant deficits in tests of spatial and pattern recognition previously shown to be sensitive to patients early in the course of probable Alzheimer's disease and only a few patients exhibited impairment on the Warrington Recognition Memory Test. There were impairments on other tests of visual memory and learning relative to matched controls, but these could not easily be related to fundamental deficits of memory or learning. Thus, on a matching-to-sample task the patients were impaired at simultaneous but not delayed matching to sample, whereas difficulties in a pattern-location learning task were more evident at its initial, easier stages. The MSA group showed no consistent evidence of intellectual deterioration as assessed from their performance on subtests of the Wechsler Adult Intelligence Scale (WAIS) and the National Adult Reading Test (NART). Consideration of individual cases showed that there was some heterogeneity in the pattern of deficits in the MSA group, with one patient showing no impairment, even in the face of considerable physical disability. The results show a distinctive pattern of cognitive deficits, unlike those previously seen using the same tests in patients with Parkinson's and Alzheimer's diseases, and suggesting a prominent frontal-lobe-like component. The implications for concepts of 'subcortical' dementia and 'fronto-striatal' cognitive dysfunction are considered