7,643 research outputs found

    Guarded Second-Order Logic, Spanning Trees, and Network Flows

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    According to a theorem of Courcelle monadic second-order logic and guarded second-order logic (where one can also quantify over sets of edges) have the same expressive power over the class of all countable kk-sparse hypergraphs. In the first part of the present paper we extend this result to hypergraphs of arbitrary cardinality. In the second part, we present a generalisation dealing with methods to encode sets of vertices by single vertices

    Spectrum of the Dirac Operator and Multigrid Algorithm with Dynamical Staggered Fermions

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    Complete spectra of the staggered Dirac operator \Dirac are determined in quenched four-dimensional SU(2)SU(2) gauge fields, and also in the presence of dynamical fermions. Periodic as well as antiperiodic boundary conditions are used. An attempt is made to relate the performance of multigrid (MG) and conjugate gradient (CG) algorithms for propagators with the distribution of the eigenvalues of~\Dirac. The convergence of the CG algorithm is determined only by the condition number~κ\kappa and by the lattice size. Since~κ\kappa's do not vary significantly when quarks become dynamic, CG convergence in unquenched fields can be predicted from quenched simulations. On the other hand, MG convergence is not affected by~κ\kappa but depends on the spectrum in a more subtle way.Comment: 19 pages, 8 figures, HUB-IEP-94/12 and KL-TH 19/94; comes as a uuencoded tar-compressed .ps-fil

    On Second-Order Monadic Monoidal and Groupoidal Quantifiers

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    We study logics defined in terms of second-order monadic monoidal and groupoidal quantifiers. These are generalized quantifiers defined by monoid and groupoid word-problems, equivalently, by regular and context-free languages. We give a computational classification of the expressive power of these logics over strings with varying built-in predicates. In particular, we show that ATIME(n) can be logically characterized in terms of second-order monadic monoidal quantifiers

    Reclaiming professional identity through postgraduate professional development: Career practitioners reclaiming their professional selves

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    Careers advisers in the UK have experienced significant change and upheaval within their professional practice. This research explores the role of postgraduate level professional development in contributing to professional identity. The research utilises a case study approach and adopts multiple tools to provide an in-depth examination of practitioners’ perceptions of themselves as professionals within their lived world experience. It presents a group of practitioners struggling to define themselves as professionals due to changing occupational nomenclature resulting from shifting government policy. Postgraduate professional development generated a perceived enhancement in professional identity through exposure to theory, policy and opportunities for reflection, thus contributing to more confident and empowered practitioners. Engagement with study facilitated development of confident, empowered practitioners with a strengthened sense of professional self

    Reflections on the implementation of the Gifted and Talented policy in England, 1999–2011

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    This paper, as part of an on-going study looking at the impact of gifted and talented policies on an inner-city school, explores the role of the local authority in implementing the various gifted and talented initiatives since 1999, when local authority gifted and talented co-ordinators were first appointed under the Excellence in Cities (DfEE, 1999) programme

    Evaluating Lifeworld as an emancipatory methodology

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    Disability research is conducted within a highly politicised ‘hotbed’ of competing paradigms and principles. New researchers, who want to work within the social model, are soon faced with complex and challenging methodological and philosophical dilemmas. The social model advocates research agendas that are focused on the emancipation and empowerment of disabled people but, in reality, these are rarely achieved. To be successful researchers need to engage with innovative and creative methodologies and to share their experiences of these within environments that welcome challenge and debate. This paper focuses on Lifeworld and assesses its value as a tool for emancipatory research. Using examples from a study with parents, whose children were in the process of being labelled as having autism, the paper illustrates how the principles that ‘underpin’ the methodology offered a supportive framework for a novice researcher

    Reflections on the implementation of the Gifted and Talented policy in England, 1999–2011

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    This paper, as part of an on-going study looking at the impact of gifted and talented policies on an inner-city school, explores the role of the local authority in implementing the various gifted and talented initiatives since 1999, when local authority gifted and talented co-ordinators were first appointed under the Excellence in Cities (DfEE, 1999) programme

    Differentiating normal and problem gambling: a grounded theory approach.

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    A previous study (Ricketts &amp; Macaskill, 2003) delineated a theory of problem gambling based on the experiences of treatment seeking male gamblers and allowed predictions to be made regarding the processes that differentiate between normal and problem gamblers. These predictions are the focus of the present study, which also utilised a grounded theory approach, but with a sample of male high frequency normal gamblers. The findings suggest that there are common aspects of gambling associated with arousal and a sense of achievement. The use of gambling to manage negative emotional states differentiated normal and problem gambling. Perceived self-efficacy , emotion management skills and perceived likelihood of winning money back were intervening variables differentiating problem and normal gamblers.</p

    Prevalence of sexual harassment among Norwegian female elite athletes in relation to sport type

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    Although it is often assumed that the prevalence of sexual harassment is different in different sports, this assumption has not been empirically tested. This study considers whether the experience of sexual harassment varies by sport. The female elite athletes (N = 553) in the study participated in 56 different sport disciplines. These were grouped as follows :1) team or individual sports; 2) extent to which clothing required for competition is revealing ; 3) gender structure (male-or female dominated membership statistics); and 4) gender culture (masculine, gender-neutral, or feminine). The data show that sexual harassment occurs in every sport group. Female elite athletes who participated in ‘masculine’ sports appear to experience more harassment than women in the other groups. We conclude that, when it comes to female athletes’ experiences of sexual harassment, sport type matters far less than sport participation per se

    Macroalgae Decrease Growth and Alter Microbial Community Structure of the Reef-Building Coral, Porites astreoides

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    This is the publisher’s final pdf. The published article is copyrighted by the Public Library of Science and can be found at: http://www.plosone.org/home.action.With the continued and unprecedented decline of coral reefs worldwide, evaluating the factors that contribute to coral demise is of critical importance. As coral cover declines, macroalgae are becoming more common on tropical reefs. Interactions between these macroalgae and corals may alter the coral microbiome, which is thought to play an important role in colony health and survival. Together, such changes in benthic macroalgae and in the coral microbiome may result in a feedback mechanism that contributes to additional coral cover loss. To determine if macroalgae alter the coral microbiome, we conducted a field-based experiment in which the coral Porites astreoides was placed in competition with five species of macroalgae. Macroalgal contact increased variance in the coral-associated microbial community, and two algal species significantly altered microbial community composition. All macroalgae caused the disappearance of a γ-proteobacterium previously hypothesized to be an important mutualist of P. astreoides. Macroalgal contact also triggered: 1) increases or 2) decreases in microbial taxa already present in corals, 3) establishment of new taxa to the coral microbiome, and 4) vectoring and growth of microbial taxa from the macroalgae to the coral. Furthermore, macroalgal competition decreased coral growth rates by an average of 36.8%. Overall, this study found that competition between corals and certain species of macroalgae leads to an altered coral microbiome, providing a potential mechanism by which macroalgae-coral interactions reduce coral health and lead to coral loss on impacted reefs
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