Information propagation through quantum chains with fluctuating disorder

We investigate the propagation of information through one-dimensional quantum chains in fluctuating external fields. We find that information propagation is suppressed, but in a quite different way compared to the situation with static disorder. We study two settings: (i) a general model where an unobservable fluctuating field acts as a source of decoherence; (ii) the XX model with both observable and unobservable fluctuating fields. In the first setting we establish a noise threshold below which information can propagate ballistically and above which information is localised. In the second setting we find localisation for all levels of unobservable noise, whilst an observable field can yield diffusive propagation of information.Comment: 5 pages, 2 figure

Bounds on Information Propagation in Disordered Quantum Spin Chains

We investigate the propagation of information through the disordered XY model. We find, with a probability that increases with the size of the system, that all correlations, both classical and quantum, are suppressed outside of an effective lightcone whose radius grows at most polylogarithmically with |t|.Comment: 4 pages, pdflatex, 1 pdf figure. Corrected the bound for the localised propagator and quantified the probability it bound occur

Theory of the Spatio-Temporal Dynamics of Transport Bifurcations

The development and time evolution of a transport barrier in a magnetically confined plasma with non-monotonic, nonlinear dependence of the anomalous flux on mean gradients is analyzed. Upon consideration of both the spatial inhomogeneity and the gradient nonlinearity of the transport coefficient, we find that the transition develops as a bifurcation front with radially propagating discontinuity in local gradient. The spatial location of the transport barrier as a function of input flux is calculated. The analysis indicates that for powers slightly above threshold, the barrier location $x_b(t) \sim ( D_n t (P-P_c)/P_c)^{1/2},$ where $P_c$ is the local transition power threshold and $D_n$ is the neoclassical diffusivity . This result suggests a simple explanation of the high disruptivity observed in reversed shear plasmas. The basic conclusions of this theory are insensitive to the details of the local transport model.Comment: 21 page Tex file, 10 postscript file

Developing content for a process-of-care checklist for use in intensive care units: a dual-method approach to establishing construct validity

Background: In the intensive care unit (ICU), checklists can be used to support the delivery of quality and consistent clinical care. While studies have reported important benefits for clinical checklists in this context, lack of formal validity testing in the literature prompted the study aim; to develop relevant `process-of-care? checklist statements, using rigorously applied and reported methods that were clear, concise and reflective of the current evidence base. These statements will be sufficiently instructive for use by physicians during ICU clinical rounds. Methods: A dual-method approach was utilized; semi-structured interviews with local clinicians; and rounds of surveys to an expert Delphi panel. The interviews helped determine checklist item inclusion/exclusion prior to the first round Delphi survey. The panel for the modified-Delphi technique consisted of local intensivists and a state- wide ICU quality committee. Minimum standards for consensus agreement were set prior to the distribution of questionnaires, and rounds of surveys continued until consensus was achieved. Results: A number of important issues such as overlap with other initiatives were identified in interviews with clinicians and integrated into the Delphi questionnaire, but no additional checklist items were suggested, demonstrating adequate checklist coverage sourced from the literature. These items were verified by local clinicians as being relevant to ICU and important elements of care that required checking during ward rounds. Two rounds of Delphi surveys were required to reach consensus on nine checklist statements: nutrition, pain management, sedation, deep vein thrombosis and stress ulcer prevention, head-of-bed elevation, blood glucose levels, readiness to extubate, and medications. Conclusions: Statements were developed as the most clear, concise, evidence-informed and instructive statements for use during clinical rounds in an ICU. Initial evidence in support of the checklist?s construct validity was established prior to further prospective evaluation in the same ICU

Evaluation of the Environmental Impact of Milk Quotas

The aim of this study is to examine the environmental impacts of the different systems for allocation and transfer of milk quota under the Common Agricultural Policy (CAP) in individual Member States of the European Union (EU). In particular, it seeks to identify the ways in which differences in the implementation of milk quota regimes can impact on various sectoral and farm management trends and the environmental implications of these

The Influence of Air Pollution on Corticolous Lichens near the Strathcona Industrial Area, Alberta

Lichens that grow on the bark of mature trees were studied at 35 sites along an air pollution gradient east of Edmonton, Alberta. Data on species composition, richness, and cover were recorded in October 1999 in a matrix of sites that extends from a known source of pollutants (the Strathcona Industrial Area) east across Strathcona County. Air pollution is affecting the corticolous lichen community. Lichen species richness and total cover increased with distance from the pollution source. Species richness in areas distant from pollution was roughly twice that in areas near the Strathcona Industrial Area. Xanthoria fallax and Phaeophyscia orbicularis were the most pollution tolerant lichens. Xanthoria hasseana, Ochrolechia arborea, Physcia adscendens, Parmelia sulcata, and Melanelia albertana were rare or absent near the pollution source and common in more distant areas. Most of the 15 species assessed were sensitive to air quality to some degree. Some lichens near the refineries and in Sherwood Park showed abnormal coloration and poor thallus integrity indicative of stress. We discuss implications for human health

Spilling over from the Street: Contextualising Domestic Space in an Inner City Neighbourhood

This article considers a series of challenges to homemaking in a post-industrial urban neighborhood in the UK, analyzing the local contextualization of domestic space. Based on a series of in-depth interviews with a diverse range of residents, the article investigates what happens when the forces of “outside” move into the “private” space of the home. Starting with a discussion of the neighborhood in question and the associated contexts of high population turnover and the local housing market, it progresses to focus on three material examples of the tension between inside and outside: the threshold sites of windows and doors, the situation of the renting resident, and home possessions themselves. Ultimately, the article illustrates the high levels of porosity of domestic space, arguing that inside the home cannot be understood without reference to both the immediate contexts of the street and wider structural economic forces, and highlighting the value of using material culture for investigating these issues