Public geographies II: being organic

This second report on ‘public geographies' considers the diverse, emergent and shifting spaces of engaging with and in public/s. Taking as its focus the more ‘organic’ rather than ‘traditional’ approach to doing public geography, as discussed in the first report, it explores the multiple and unorthodox ways in which engagements across academic-public spheres play out, and what such engagements may mean for geography/ers. The report first explores the role of the internet in ‘enabling conversations', generating a range of opportunities for public geography through websites, wikis, blogs, file-sharing sites, discussion forums and more, thinking critically about how technologies may enable/disable certain kinds of publically engaged activities. It then considers issues of process and praxis: how collaborations with groups/communities/organizations beyond academia are often unplanned, serendipitous encounters that evolve organically into research/learning/teaching endeavours; but also that personal politics/positionality bring an agency to bear upon whether we, as academics, follow the leads we may stumble upon. The report concludes with a provocative question – given that many non-academics appear to be doing some amazing and inspiring projects and activities, thoughtful, critical and (arguably) examples of organic public geographies, what then is academia’s role

Surface effects on the orbital order in the single layered manganite La0.5Sr1.5MnO4

We report the first observation of `orbital truncation rods' -- the scattering arising from the termination of bulk orbital order at the surface of a crystal. The x-ray measurements, performed on a cleaved, single-layered perovskite, La0.5Sr1.5MnO4, reveal that while the crystallographic surface is atomically smooth, the orbital `surface' is much rougher, with an r.m.s. deviation from the average `surface' of ~0.7nm. The temperature dependence of this scattering shows evidence of a surface-induced second order transition.Comment: 13 pages, 4 figure

Parametric ordering of complex systems

Cellular automata (CA) dynamics are ordered in terms of two global parameters, computable {\sl a priori} from the description of rules. While one of them (activity) has been used before, the second one is new; it estimates the average sensitivity of rules to small configurational changes. For two well-known families of rules, the Wolfram complexity Classes cluster satisfactorily. The observed simultaneous occurrence of sharp and smooth transitions from ordered to disordered dynamics in CA can be explained with the two-parameter diagram

The Evolutionary Status of SS433

We consider possible evolutionary models for SS 433. We assume that common-envelope evolution is avoided if radiation pressure is able to expel most of a super-Eddington accretion flow from a region smaller than the accretor's Roche lobe. This condition is satisfied, at least initially, for largely radiative donors with masses in the range 4-12 solar masses. For donors more massive than about 5 solar masses, moderate mass ratios q = M_2/M_1 > 1 are indicated, thus tending to favor black-hole accretors. For lower mass donors, evolutionary considerations do not distinguish between a neutron star or black hole accretor. In all cases the mass transfer (and mass loss) rates are much larger than the likely mass-loss rate in the precessing jets. Almost all of the transferred mass is expelled at radii considerably larger than the jet acceleration region, producing the "stationary" H-alpha line, the infrared luminosity, and accounting for the low X-ray luminosity.Comment: 13 pages, Astrophysical Journal Letters, accepte

Super-Eddington Atmospheres that Don't Blow Away

We show that magnetized, radiation dominated atmospheres can support steady state patterns of density inhomogeneity that enable them to radiate at far above the Eddington limit, without suffering mass loss. The inhomogeneities consist of periodic shock fronts bounding narrow, high-density regions, interspersed with much broader regions of low density. The radiation flux avoids the regions of high density, which are therefore weighed down by gravity, while gas in the low-density regions is slammed upward into the shock fronts by radiation force. As the wave pattern moves through the atmosphere, each parcel of matter alternately experiences upward and downward forces, which balance on average. Magnetic tension shares the competing forces between regions of different densities, preventing the atmosphere from blowing apart. We calculate the density structure and phase speed of the wave pattern, and relate these to the wavelength, the density contrast, and the factor by which the net radiation flux exceeds the Eddington limit. In principle, this factor can be as large as the ratio of magnetic pressure to mean gas pressure, or the ratio of radiation pressure to gas pressure, whichever is smaller. Although the magnetic pressure must be large compared to the mean gas pressure in order to support a large density contrast, it need not be large compared to the radiation pressure. These highly inhomogeneous flows could represent the nonlinear development of the "photon bubble" instability discovered by Gammie. We briefly discuss the applicability of these solutions to astrophysical systems.Comment: 11 pages, 1 figure, accepted for publication in The Astrophysical Journa

Adaptation to the Edge of Chaos in the Self-Adjusting Logistic Map

Self-adjusting, or adaptive systems have gathered much recent interest. We present a model for self-adjusting systems which treats the control parameters of the system as slowly varying, rather than constant. The dynamics of these parameters is governed by a low-pass filtered feedback from the dynamical variables of the system. We apply this model to the logistic map and examine the behavior of the control parameter. We find that the parameter leaves the chaotic regime. We observe a high probability of finding the parameter at the boundary between periodicity and chaos. We therefore find that this system exhibits adaptation to the edge of chaos.Comment: 3 figure

“some kind of thing it aint us but yet its in us”: David Mitchell, Russell Hoban, and metafiction after the millennium

This article appraises the debt that David Mitchell’s Cloud Atlas owes to the novels of Russell Hoban, including, but not limited to, Riddley Walker. After clearly mapping a history of Hoban’s philosophical perspectives and Mitchell’s inter-textual genre-impersonation practice, the article assesses the degree to which Mitchell’s metatextual methods indicate a nostalgia for by-gone radical aesthetics rather than reaching for new modes of its own. The article not only proposes several new backdrops against which Mitchell’s novel can be read but also conducts the first in-depth appraisal of Mitchell’s formal linguistic replication of Riddley Walker

Assessing the effects of the first 2 years of industry-led badger culling in England on the incidence of bovine tuberculosis in cattle in 2013–2015

Culling badgers to control the transmission of bovine tuberculosis (TB) between this wildlife reservoir and cattle has been widely debated. Industry-led culling began in Somerset and Gloucestershire between August and November 2013 to reduce local badger populations. Industry-led culling is not designed to be a randomised and controlled trial of the impact of culling on cattle incidence. Nevertheless, it is important to monitor the effects of the culling and, taking the study limitations into account, perform a cautious evaluation of the impacts. A standardised method for selecting areas matched to culling areas in factors found to affect cattle TB risk has been developed to evaluate the impact of badger culling on cattle TB incidence. The association between cattle TB incidence and badger culling in the first two years has been assessed. Descriptive analyses without controlling for confounding showed no association between culling and TB incidence for Somerset, or for either of the buffer areas for the first two years since culling began. A weak association was observed in Gloucestershire for Year 1 only. Multivariable analysis adjusting for confounding factors showed that reductions in TB incidence were associated with culling in the first two years in both the Somerset and Gloucestershire intervention areas when compared to areas with no culling (IRR: 0.79, 95%CI: 0.72-0.87, p<0.001 and IRR: 0.42, 95%CI: 0.34-0.51, p<0.001 respectively). An increase in incidence was associated with culling in the 2 km buffer surrounding the Somerset intervention area (IRR: 1.38, 95%CI: 1.09-1.75, p=0.008), but not in Gloucestershire (IRR: 0.91, 95%CI: 0.77-1.07, p=0.243). As only two intervention areas with two years’ of data are available for analysis, and the biological cause-effect relationship behind the statistical associations is difficult to determine, it would be unwise to use these findings to develop generalisable inferences about the effectiveness of the policy at present