1,481 research outputs found

    Bioreactor scalability: laboratory-scale bioreactor design influences performance, ecology, and community physiology in expanded granular sludge bed bioreactors

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    Studies investigating the feasibility of new, or improved, biotechnologies, such as wastewater treatment digesters, inevitably start with laboratory-scale trials. However, it is rarely determined whether laboratory-scale results reflect full-scale performance or microbial ecology. The Expanded Granular Sludge Bed (EGSB) bioreactor, which is a high-rate anaerobic digester configuration, was used as a model to address that knowledge gap in this study. Two laboratory-scale idealizations of the EGSB—a one-dimensional and a three- dimensional scale-down of a full-scale design—were built and operated in triplicate under near-identical conditions to a full-scale EGSB. The laboratory-scale bioreactors were seeded using biomass obtained from the full-scale bioreactor, and, spent water from the distillation of whisky from maize was applied as substrate at both scales. Over 70 days, bioreactor performance, microbial ecology, and microbial community physiology were monitored at various depths in the sludge-beds using 16S rRNA gene sequencing (V4 region), specific methanogenic activity (SMA) assays, and a range of physical and chemical monitoring methods. SMA assays indicated dominance of the hydrogenotrophic pathway at full-scale whilst a more balanced activity profile developed during the laboratory-scale trials. At each scale, Methanobacterium was the dominant methanogenic genus present. Bioreactor performance overall was better at laboratory-scale than full-scale. We observed that bioreactor design at laboratory-scale significantly influenced spatial distribution of microbial community physiology and taxonomy in the bioreactor sludge-bed, with 1-D bioreactor types promoting stratification of each. In the 1-D laboratory bioreactors, increased abundance of Firmicutes was associated with both granule position in the sludge bed and increased activity against acetate and ethanol as substrates. We further observed that stratification in the sludge-bed in 1-D laboratory-scale bioreactors was associated with increased richness in the underlying microbial community at species (OTU) level and improved overall performance

    From strategy, to accounting : accounting practice and strategic discourse in the telecommunications industry

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    Following Roberts (1990) and Dent (1990). this study investigates the importance of complexifying the relationship between strategy and accounting. The genealogical approach of Hoskin et al (1997) provides inspiration as to the ways in which strategic discourse (itself promoted as a subject of study by Knights and Morgan (1990,1991,1995)) is historically contingent upon practices of accounting. I take up this task of inaugurating the study of accounting practice and strategy discourse, from strategy to accounting, to develop a new perspective of how their interaction takes place. This gives birth to a re-reading of the strategy (and accounting) literatures, from the direction of a constitutive notion of accounting practices. In particular, the processual and critical schools of strategy are found to promote conventional notions of accounting as mirror, as secondary and passive practice, which circulate beneath the usual level of visibility. Building on this emergent approach, a post- Foucauldian theory of practices is outlined from a methodological viewpoint. This approach does not begin from such general categories as 'the individual', 'the social' or 'the economic', and thereby does not follow conventional understandings of 'doing ethnography'. The inquiry is empirically situated within the context of a longitudinal investigation (1997-2000) into the U. K. based part of a global telecommunications company, Teleco. I discover complex interactions between accounting practices and the workings of strategy, both as presence and absence. There is a partial presence of strategy even within the most 'strategic' parts of Teleco, in conjunction with a growing absence within those parts most distant from 'the strategy'. Despite this, or perhaps because of this, the spread of accounting and accounting based-practices rolls on, albeit in a non-uniform way. This brings forth the possibility of a strategic accounting, one whose practices are perhaps most visibly internalised and effected on my very self, thus adding weight to the rejection within this thesis of the metaphysical categories of either 'strategy' or 'accounting

    Prescription Opioid Abuse in Prison Settings: A Systematic Review of Prevalence, Practice and Treatment Responses

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    Background To systematically review the quantitative and qualitative evidence base pertaining to the prevalence, practice of, and treatment response to the diversion of prescribed opiates in the prison setting. Methods Medline, Embase, CINAHL, PsycINFO, Google Scholar, ASSIA and Science Direct databases were searched for papers from 1995 to the present relevant to the abuse of prescribed opiate medication. Identified journals and their reference lists were hand searched for other relevant articles. Of the abstracts identified as relevant, full text papers were retrieved and critiqued against the inclusion criteria for the review. Results Three hundred and fifty-five abstracts were identified, leading to 42 full-text articles being retrieved. Of those, 10 papers were included in the review. Significant differences in abuse behaviours between different countries were reported. However, a key theme emerged from the data regarding a culture of nasal administration of prescribed sublingual buprenorphine within some prisons due to 3 both reduced prevalence of injection within prison and reduced supplies of illicit drugs within prison. The buprenorphine/naloxone preparation appears to be less amenable to abuse. The review highlighted a paucity of empirical research pertaining to both prevalence of the phenomenon and treatment responses. Clinical and research implications Healthcare providers within prisons need to prescribe opioids in the least abuseable preparation since the risk of abuse is significant, despite widespread processes of supervised dispensing. Prescription medication abuse is not limited to opioids and the predominant drug of abuse in an individual prison can rapidly change according to availability

    Canonical Ensemble of Initial States Leading to Chiral Fluctuations

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    In energetic heavy ion collisions, if quark-gluon plasma is formed, its hadronization may lead to observable critical fluctuations, i.e., DCC formation. The strength and observability of these fluctuations depend on the initial state. Here we study the canonical ensemble of initial states of chiral fluctuations in heavy ion collisions and the probability to obtain observable domains of chiral condensates.Comment: 13 pages (figures included) Accepted for publication in Phys. Rev.

    Semi-numerical resummation of event shapes

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    For many event-shape observables, the most difficult part of a resummation in the Born limit is the analytical treatment of the observable's dependence on multiple emissions, which is required at single logarithmic accuracy. We present a general numerical method, suitable for a large class of event shapes, which allows the resummation specifically of these single logarithms. It is applied to the case of the thrust major and the oblateness, which have so far defied analytical resummation and to the two-jet rate in the Durham algorithm, for which only a subset of the single logs had up to now been calculated.Comment: 29 pages, 7 figures. Version 2 adds some clarifications, a reference, as well as corrections to the subleading fixed-order coefficients and to figures 4 and

    Disoriented Chiral Condensates, Pion Probability Distributions and Parallels with Disordered System

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    A general expression is discussed for pion probability distributions coming from relativistic heavy ion collisions. The general expression contains as limits: 1) The disoriented chiral condensate (DCC), 2) the negative binomial distribution and Pearson type III distribution, 3) a binomial or Gaussian result, 4) and a Poisson distribution. This general expression approximates other distributions such as a signal to noise laser distribution. Similarities and differences of the DCC distribution with these other distribution are studied. A connection with the theory of disordered systems will be discussed which include spin-glasses, randomly broken objects, random and chaotic maps.Comment: 5 pages, 1 figure include

    Dileptons from Disoriented Chiral Condensates

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    Disoriented chiral condensates or long wavelength pionic oscillations and their interaction with the thermal environment can be a significant source of dileptons. We calculate the yield of such dilepton production within the linear sigma model, both in a quantal mean-field treatment and in a semi-classical approximation. We then illustrate the basic features of the dilepton spectrum in a schematic model. We find that dilepton yield with invariant mass near and below 2mπ2m_{\pi} due to the soft pion modes can be up to two orders of magnitude larger than the corresponding equilibrium yield.Comment: 22 pages, 8 figures, uses epsf-styl

    Pion Breather States in QCD

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    We describe a class of pionic breather solutions (PBS) which appear in the chiral lagrangian description of low-energy QCD. These configurations are long-lived, with lifetimes greater than 10310^3 fm/c, and could arise as remnants of disoriented chiral condensate (DCC) formation at RHIC. We show that the chiral lagrangian equations of motion for a uniformly isospin-polarized domain reduce to those of the sine-gordon model. Consequently, our solutions are directly related to the breather solutions of sine-gordon theory in 3+1 dimensions. We investigate the possibility of PBS formation from multiple domains of DCC, and show that the probability of formation is non-negligible.Comment: 9 pages, 4 figure

    Void Analysis of Hadronic Density Fluctuations at Phase Transition

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    The event-to-event fluctuations of hadron multiplicities are studied for a quark system undergoing second-order phase transition to hadrons. Emphasis is placed on the search for an observable signature that is realistic for heavy-ion collisions. It is suggested that in the 2-dimensional y-phi space the produced particles selected in a very narrow p_T window may exhibit clustering patterns even when integrated over the entire emission time. Using the Ising model to simulate the critical phenomenon and taking into account a p_T distribution that depends on the emission time, we study in the framework of the void analysis proposed earlier and find scaling behavior. The scaling exponents turn out to be larger than the ones found before for pure configurations without mixing. The signature is robust in that it is insensitive to the precise scheme of simulating time evolution. Thus it should reveal whether or not the dense matter created in heavy-ion collisions is a quark-gluon plasma before hadronization.Comment: 11 pages in LaTeX + 6 figures in p
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