1,599 research outputs found

    Integrated risk/cost planning models for the US Air Traffic system

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    A prototype network planning model for the U.S. Air Traffic control system is described. The model encompasses the dual objectives of managing collision risks and transportation costs where traffic flows can be related to these objectives. The underlying structure is a network graph with nonseparable convex costs; the model is solved efficiently by capitalizing on its intrinsic characteristics. Two specialized algorithms for solving the resulting problems are described: (1) truncated Newton, and (2) simplicial decomposition. The feasibility of the approach is demonstrated using data collected from a control center in the Midwest. Computational results with different computer systems are presented, including a vector supercomputer (CRAY-XMP). The risk/cost model has two primary uses: (1) as a strategic planning tool using aggregate flight information, and (2) as an integrated operational system for forecasting congestion and monitoring (controlling) flow throughout the U.S. In the latter case, access to a supercomputer is required due to the model's enormous size

    A Model for Classical Space-time Co-ordinates

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    Field equations with general covariance are interpreted as equations for a target space describing physical space time co-ordinates, in terms of an underlying base space with conformal invariance. These equations admit an infinite number of inequivalent Lagrangian descriptions. A model for reparametrisation invariant membranes is obtained by reversing the roles of base and target space variables in these considerations.Comment: 9 pages, Latex. This was the basis of a talk given at the Argonne National Laboratory 1996 Summer Institute : Topics on Non-Abelian Duality June 27-July 1

    Properties of the Scalar Universal Equations

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    The variational properties of the scalar so--called ``Universal'' equations are reviewed and generalised. In particular, we note that contrary to earlier claims, each member of the Euler hierarchy may have an explicit field dependence. The Euler hierarchy itself is given a new interpretation in terms of the formal complex of variational calculus, and is shown to be related to the algebra of distinguished symmetries of the first source form.Comment: 15 pages, LaTeX articl

    The relationship between regional pain with or without neuropathic symptoms and chronic widespread pain.

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    This study was performed to test whether the risk of developing chronic widespread pain (CWP) in those with regional pain was augmented in those with symptoms of neuropathic pain (NP). Persons free of CWP completed the Douleur Neuropathique 4 (scores ≄3 indicating NP); demographics; Hospital Anxiety and Depression scale; Pittsburgh Sleep Quality Index; and pain medications. Participants were classified as having no pain, regional pain with no symptoms of NP (NP-), or regional pain with symptoms of NP (NP). At the 12-month follow-up, participants with CWP were identified. Logistic regression estimated the odds ratio, with 95% confidence intervals, of CWP in the NP- and NP groups compared with no pain, and NP compared with NP-. Partial population attributable risks estimated the proportion of CWP attributable to baseline NP- or NP exposure. One thousand one hundred sixty-two participants completed the baseline DN4 and provided pain data at follow-up: 523 (45.0%) had no baseline pain, 562 (48.4%) NP-, and 77 (6.6%) NP. One hundred fifty-three (13.2%) had CWP at 12 months: 19 (3.6%) no pain, 108 (19.2%) NP-, and 26 (33.8%) NP. NP- (2.9 [1.9-4.3]) and NP (2.1 [1.1-4.0]) predicted CWP after adjusting for demographics, Hospital Anxiety and Depression scale, Pittsburgh Sleep Quality Index, and medications. The partial population attributable risk was 41.3% (25.2-54.0) for NP- and 6.0% (0.1-11.6) for NP. The NP group were not more likely to develop CWP when compared directly with NP- (1.5 [0.8-2.8]). Neuropathic pain was relatively rare and predicted a small number of new-onset CWP cases. Using these estimates, treatments targeting NP would at best prevent 6% of CWP cases

    The relationship between psychological distress and multiple tender points across the adult lifespan

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    Multiple tender points are common in the population and, in studies of mid-life adults, are strongly associated with high levels of psychological distress. Whether this relationship occurs in older adults is unclear. This cross-sectional study investigated whether high levels of psychological distress would be associated with a high tender point count and whether the relationship would be moderated by age. Three thousand three hundred and seventy-nine individuals were mailed a questionnaire which included the Hospital Anxiety and Depression (HAD) scale, the Pain Catastrophising Scale (PCS), the Brief Illness Perception Questionnaire (Brief IPQ), and the Pittsburgh Sleep Quality Index (PSQI). A random sample of approximately 10% of subjects who returned the questionnaire undertook a physical assessment, including a manual tender point count assessment.A total of 2385 (71%) subjects completed the questionnaire, of whom 798 (33%) were invited to take part in the physical assessment and 290 (12%) participated. Of the 290 participants the median age was 64 years (range 34-97) and 63% were female. The median HAD score was 9 (IQR 5-14) and the median number of tender points was 3 (range 0-7).Increasing HAD score was positively and significantly associated with tender point count, but this relationship was not moderated by age. In a final multivariable model, sex, HAD score and PSQI score were independent predictors of multiple tender points.Psychological distress was associated with multiple tender points independent of age. Psychological distress and trouble sleeping were important, potentially modifiable factors associated with the outcome

    Integrable Generalisations of the 2-dimensional Born Infeld Equation

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    The Born-Infeld equation in two dimensions is generalised to higher dimensions whilst retaining Lorentz Invariance and complete integrability. This generalisation retains homogeneity in second derivatives of the field.Comment: 11 pages, Latex, DTP/93/3

    Reading Videogames as (authorless) Literature

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    This article presents the outcomes of research, funded by the Arts and Humanities Research Council in England and informed by work in the fields of new literacy research, gaming studies and the socio-cultural framing of education, for which the videogame L.A. Noire (Rockstar Games, 2011) was studied within the orthodox framing of the English Literature curriculum at A Level (pre-University) and Undergraduate (degree level). There is a plethora of published research into the kinds of literacy practices evident in videogame play, virtual world engagement and related forms of digital reading and writing (Gee, 2003; Juul, 2005; Merchant, Gillen, Marsh and Davies, 2012; Apperley and Walsh, 2012; Bazalgette and Buckingham, 2012) as well as the implications of such for home / school learning (Dowdall, 2006; Jenkins, 2006; Potter, 2012) and for teachers’ own digital lives (Graham, 2012). Such studies have tended to focus on younger children and this research is also distinct from such work in the field in its exploration of the potential for certain kinds of videogame to be understood as 'digital transformations' of conventional ‘schooled’ literature. The outcomes of this project raise implications of such a conception for a further implementation of a ‘reframed’ literacy (Marsh, 2007) within the contemporary curriculum of a traditional and conservative ‘subject’. A mixed methods approach was adopted. Firstly, students contributing to a gamplay blog requiring them to discuss their in-game experience through the ‘language game’ of English Literature, culminating in answering a question constructed with the idioms of the subject’s set text ‘final examination’. Secondly, students taught their teachers to play L.A. Noire, with free choice over the context for this collaboration. Thirdly, participants returned to traditional roles in order to work through a set of study materials provided, designed to reproduce the conventions of the ‘study guide’ for literature education. Interviews were conducted after each phase and the outcomes informed a redrafting of the study materials which are now available online for teachers – this being the ‘practical’ outcome of the research (Berger and McDougall, 2012). In the act of inserting the study of L.A. Noire into the English Literature curriculum as currently framed, this research moves, through a practical ‘implementation’ beyond longstanding debates around narratology and ludology (Frasca, 2003; Juul, 2005) in the field of game studies (Leaning, 2012) through a direct connection to new literacy studies and raises epistemological questions about ‘subject identity’, informed by Bernstein (1996) and Bourdieu (1986) and the implications for digital transformations of texts for both ideas about cultural value in schooled literacy (Kendall and McDougall, 2011) and the politics of ‘expertise’ in pedagogic relations (Ranciere, 2009, Bennett, Kendall and McDougall, 2012a)

    Algebraic description of spacetime foam

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    A mathematical formalism for treating spacetime topology as a quantum observable is provided. We describe spacetime foam entirely in algebraic terms. To implement the correspondence principle we express the classical spacetime manifold of general relativity and the commutative coordinates of its events by means of appropriate limit constructions.Comment: 34 pages, LaTeX2e, the section concerning classical spacetimes in the limit essentially correcte

    The relationship of offending style to psychological and social risk factors in a sample of adolescent males

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    Research has indicated that life-course persistent offenders typically vary their offending style, following a criminal career progression from co to solo offending. Few studies have investigated the offenders who contemporaneously mix their style of offending. A sample of 1047 male adolescent offenders from the Pathways to Desistance study was investigated over a seven-year period. Participants were identified as solo, co or contemporaneous mixed style (CMS) offenders for each wave of data and one-way between groups analysis of variance was conducted to examine variations between the different offending styles in terms of offending frequencies, exposure to violence, peer antisocial behaviour and influence, resistance to peer influence, impulse control, and psychopathy. CMS offenders were found to consistently report significantly higher rates of offending and present significantly higher negative risk factors and lower protective risk factors than solo and co offenders for the duration of the study. A Multinomial Logistic Regression was used to investigate predictors of offending style with CMS as the reference category. Higher levels of exposure to violence and peer antisocial behaviour and lower levels of impulse control predicted membership of the CMS group for the first part of the study when compared with co-offenders; and higher levels of exposure to violence and peer antisocial behaviour continued to predict CMS offending when compared to solo offenders until the end of the study