1,443 research outputs found

    On the correct choice of equivalent circuit for fitting bulk impedance data of ionic/electronic conductors

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    Bulk conductivity data of ionically and electronically conducting solid electrolytes and electronic ceramics invariably show a frequency dependence that cannot be modelled by a single-valued resistor. To model this, common practice is to add a constant phase element (CPE) in parallel with the bulk resistance. To fit experimental data on a wide variety of materials, however, it is also essential to include the limiting, high frequency permittivity of the material in the equivalent circuit. Failure to do so can lead to incorrect values for the sample resistance and CPE parameters and to an inappropriate circuit for materials that are electrically heterogeneous

    On Sp(2M) Invariant Green Functions

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    Explicit form of two-point and three-point Sp(2M) invariant Green functions is found.Comment: 7 page

    Exercise intervention in people with cancer undergoing adjuvant cancer treatment following surgery: a systematic review

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    BackgroundRemaining physically active during and after cancer treatment is known to improve associated adverse effects, improve overall survival and reduce the probability of relapse. This systematic review addresses the question: is an exercise training programme beneficial in people with cancer undergoing adjuvant cancer treatment following surgery.MethodsA systematic database search of Embase, Ovid, Medline without Revisions, SPORTDiscus, Web of Science, Cochrane Library and ClinicalTrials.gov for any randomised controlled trials (RCT) or non-RCT addressing the effect of an exercise training programme in those having adjuvant cancer treatment following surgery was conducted.ResultsThe database search yielded 6489 candidate abstracts of which 94 references included the required terms. A total of 17 articles were included in this review. Exercise training is safe and feasible in the adjuvant setting and furthermore may improve measures of physical fitness and health related quality of life (HRQoL).ConclusionThis is the first systematic review on exercise training interventions in people with cancer undergoing adjuvant cancer treatment following surgery. Due to the lack of adequately powered RCTs in this area, it remains unclear whether exercise training in this context improves clinical outcomes other physical fitness and HRQoL. It remains unclear what is the optimal timing of initiation of an exercise programme and what are the best combinations of elements within an exercise training programme to optimise training efficacy. Furthermore, it is unclear if initiating such exercise programmes at cancer diagnosis may have a long-lasting effect on physically activity throughout the subsequent life course

    A New Lower Bound on the Maximum Number of Satisfied Clauses in Max-SAT and its Algorithmic Applications

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    A pair of unit clauses is called conflicting if it is of the form (x)(x), (xˉ)(\bar{x}). A CNF formula is unit-conflict free (UCF) if it contains no pair of conflicting unit clauses. Lieberherr and Specker (J. ACM 28, 1981) showed that for each UCF CNF formula with mm clauses we can simultaneously satisfy at least \pp m clauses, where \pp =(\sqrt{5}-1)/2. We improve the Lieberherr-Specker bound by showing that for each UCF CNF formula FF with mm clauses we can find, in polynomial time, a subformula FF' with mm' clauses such that we can simultaneously satisfy at least \pp m+(1-\pp)m'+(2-3\pp)n"/2 clauses (in FF), where n"n" is the number of variables in FF which are not in FF'. We consider two parameterized versions of MAX-SAT, where the parameter is the number of satisfied clauses above the bounds m/2m/2 and m(51)/2m(\sqrt{5}-1)/2. The former bound is tight for general formulas, and the later is tight for UCF formulas. Mahajan and Raman (J. Algorithms 31, 1999) showed that every instance of the first parameterized problem can be transformed, in polynomial time, into an equivalent one with at most 6k+36k+3 variables and 10k10k clauses. We improve this to 4k4k variables and (25+4)k(2\sqrt{5}+4)k clauses. Mahajan and Raman conjectured that the second parameterized problem is fixed-parameter tractable (FPT). We show that the problem is indeed FPT by describing a polynomial-time algorithm that transforms any problem instance into an equivalent one with at most (7+35)k(7+3\sqrt{5})k variables. Our results are obtained using our improvement of the Lieberherr-Specker bound above

    Supersymmetric Euler-Heisenberg effective action: Two-loop results

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    The two-loop Euler-Heisenberg-type effective action for N = 1 supersymmetric QED is computed within the background field approach. The background vector multiplet is chosen to obey the constraints D_\a W_\b = D_{(\a} W_{\b)} = const, but is otherwise completely arbitrary. Technically, this calculation proves to be much more laborious as compared with that carried out in hep-th/0308136 for N = 2 supersymmetric QED, due to a lesser amount of supersymmetry. Similarly to Ritus' analysis for spinor and scalar QED, the two-loop renormalisation is carried out using proper-time cut-off regularisation. A closed-form expression is obtained for the holomorphic sector of the two-loop effective action, which is singled out by imposing a relaxed super self-duality condition.Comment: 27 pages, 2 eps figures, LaTeX; V2: typos corrected, comments and reference adde

    The relationship between leader support, staff influence over decision making, work pressure and patient satisfaction : a cross-sectional analysis of NHS datasets in England

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    Objective To explore the relationships between leader support, staff influence over decisions, work pressure and patient satisfaction. Design A cross-sectional study of large National Health Service (NHS) datasets in England in 2010. Setting and participants 158 NHS acute hospital trusts in England (n=63 156) from all staff groups. Primary and secondary outcome measures Survey data measuring leader support, staff influence over decision making, staff work pressure and objective outcome data measuring patient satisfaction. Results Multilevel serial mediation analysis showed a significantly positive association between leader support and staff influence over decisions (B=0.74, SE=0.07, p<0.01). Furthermore, staff influence over decisions showed a negative association with staff work pressure (B=−0.84, SE=0.41, p<0.05) which in turn was negatively linked to patient satisfaction (B=−17.50, SE=4.34, p<0.01). Serial mediation showed a positive indirect effect of leader support on patient satisfaction via staff influence over decisions and work pressure (B=10.96, SE=5.55, p<0.05). Conclusions and implications Our results provide evidence that leader support influences patient satisfaction through shaping staff experience, particularly staff influence over decisions and work pressure. Patients’ care is dependent on the health, well-being, and effectiveness of the NHS workforce. That, in turn, is determined by the extent to which leaders are supportive in ensuring that work environments are managed in a way which protects the well-being of staff

    Hermitian versus holomorphic complex and quaternionic generalized supersymmetries of the M-theory. A classification

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    Relying upon the division-algebra classification of Clifford algebras and spinors, a classification of generalized supersymmetries (or, with a slight abuse of language,"generalized supertranslations") is provided. In each given space-time the maximal, saturated, generalized supersymmetry, compatible with the division-algebra constraint that can be consistently imposed on spinors and on superalgebra generators, is furnished. Constraining the superalgebra generators in both the complex and the quaternionic cases gives rise to the two classes of constrained hermitian and holomorphic generalized supersymmetries. In the complex case these two classes of generalized supersymmetries can be regarded as complementary. The quaternionic holomorphic supersymmetry only exists in certain space-time dimensions and can admit at most a single bosonic scalar central charge. The results here presented pave the way for a better understanding of the various MM algebra-type of structures which can be introduced in different space-time signatures and in association with different division algebras, as well as their mutual relations. In a previous work, e.g., the introduction of a complex holomorphic generalized supersymmetry was shown to be necessary in order to perform the analytic continuation of the standard MM-theory to the 11-dimensional Euclidean space. As an application of the present results, it is shown that the above algebra also admits a 12-dimensional, Euclidean, FF-algebra presentation.Comment: 25 pages, LaTe

    A note on spin-s duality

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    Duality is investigated for higher spin (s2s \geq 2), free, massless, bosonic gauge fields. We show how the dual formulations can be derived from a common "parent", first-order action. This goes beyond most of the previous treatments where higher-spin duality was investigated at the level of the equations of motion only. In D=4 spacetime dimensions, the dual theories turn out to be described by the same Pauli-Fierz (s=2) or Fronsdal (s3s \geq 3) action (as it is the case for spin 1). In the particular s=2 D=5 case, the Pauli-Fierz action and the Curtright action are shown to be related through duality. A crucial ingredient of the analysis is given by the first-order, gauge-like, reformulation of higher spin theories due to Vasiliev.Comment: Minor corrections, reference adde

    Dynamics of Higher Spin Fields and Tensorial Space

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    The structure and the dynamics of massless higher spin fields in various dimensions are reviewed with an emphasis on conformally invariant higher spin fields. We show that in D=3,4,6 and 10 dimensional space-time the conformal higher spin fields constitute the quantum spectrum of a twistor-like particle propagating in tensorial spaces of corresponding dimensions. We give a detailed analysis of the field equations of the model and establish their relation with known formulations of free higher spin field theory.Comment: JHEP3 style, 40 pages; v2 typos corrected, comments and references added; v3 published versio

    An evaluation of the stimulants and impediments to innovation within PFI/PPP projects

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    This paper identifies the theoretical stimulants and impediments associated with the implementation of PFI/PPP (Private Finance Initiative/Public Private Partnership) projects. A current defect of this procurement approach is the unintentional constraint upon the innovations incorporated into the development of PFI projects. A critical evaluation of the published literature has been utilized to synthesize a theoretical model. The paper proposes a theoretical model for the identification of potential innovation stimulants and impediments within this type of procurement. This theoretical model is then utilised to evaluate four previously completed PFI projects. These project case-studies have been examined in detail. The evaluation demonstrates how ineffective current procedures are. The application of this model before project letting could eliminate unintentional constraints and stimulate improved innovation within the process. The implementation of the model could improve the successful delivery of innovation within the entire PFI/PPP procurement process
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