838 research outputs found

    Chronic dermatomycoses of the foot as risk factors for acute bacterial cellulitis of the leg: A case-control study

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    Objective: To assess the role of foot dermatomycosis ( tinea pedis and onychomycosis) and other candidate risk factors in the development of acute bacterial cellulitis of the leg. Methods: A case-control study, including 243 patients ( cases) with acute bacterial cellulitis of the leg and 467 controls, 2 per case, individually matched for gender, age (+/-5 years), hospital and admission date (+/-2 months). Results: Overall, mycology-proven foot dermatomycosis was a significant risk factor for acute bacterial cellulitis (odds ratio, OR: 2.4; p < 0.001), as were tinea pedis interdigitalis (OR: 3.2; p < 0.001), tinea pedis plantaris (OR: 1.7; p = 0.005) and onychomycosis (OR: 2.2; p < 0.001) individually. Other risk factors included: disruption of the cutaneous barrier, history of bacterial cellulitis, chronic venous insufficiency and leg oedema. Conclusions: Tinea pedis and onychomycosis were found to be significant risk factors for acute bacterial cellulitis of the leg that are readily amenable to treatment with effective pharmacological therapy. Copyright (C) 2004 S. Karger AG, Basel

    Prophylactic radiotherapy against heterotopic ossification following internal fixation of acetabular fractures: a comparative estimate of risk.

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    OBJECTIVE: Radiotherapy (RT) is effective in preventing heterotopic ossification (HO) around acetabular fractures requiring surgical reconstruction. We audited outcomes and estimated risks from RT prophylaxis, and alternatives of indometacin or no prophylaxis. METHODS: 34 patients underwent reconstruction of acetabular fractures through a posterior approach, followed by a 8-Gy single fraction. The mean age was 44 years. The mean time from surgery to RT was 1.1 days. The major RT risk is radiation-induced fatal cancer. The International Commission on Radiological Protection (ICRP) method was used to estimate risk, and compared with a method (Trott and Kemprad) specifically for estimating RT risk for benign disease. These were compared with risks associated with indometacin and no prophylaxis. RESULTS: 28 patients (82%) developed no HO; 6 developed Brooker Class I; and none developed Class II-IV HO. The ICRP method suggests a risk of fatal cancer in the range of 1 in 1000 to 1 in 10,000; the Trott and Kemprad method suggests 1 in 3000. For younger patients, this may rise to 1 in 2000; and for elderly patients, it may fall to 1 in 6000. The risk of death from gastric bleeding or perforation from indometacin is 1 in 180 to 1 in 900 in older patients. Without prophylaxis risk of death from reoperation to remove HO is 1 in 4000 to 1 in 30,000. CONCLUSION: These results are encouraging, consistent with much larger series and endorse our multidisciplinary management. Risk estimates can be used in discussion with patients. ADVANCES IN KNOWLEDGE: The risk from RT prophylaxis is small, it is safer than indometacin and substantially overlaps with the range for no prophylaxis.NGB is supported by the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre. JES is supported by Cancer Research UK through the Cambridge Cancer Centre.This is the accepted manuscript version. The final version is available from the BIR at http://www.birpublications.org/doi/abs/10.1259/bjr.20140398?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed&

    Sigma models with off-shell N=(4,4) supersymmetry and noncommuting complex structures

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    We describe the conditions for extra supersymmetry in N=(2,2) supersymmetric nonlinear sigma models written in terms of semichiral superfields. We find that some of these models have additional off-shell supersymmetry. The (4,4) supersymmetry introduces geometrical structures on the target-space which are conveniently described in terms of Yano f-structures and Magri-Morosi concomitants. On-shell, we relate the new structures to the known bi-hypercomplex structures.Comment: 20 pages; v2: significant corrections, clarifications, and reorganization; v3: discussion of supersymmetry vs twisted supersymmetry added, relevant signs corrected

    Imaging Subtle Microstructural Variations in Ceramics with Precision Ultrasonic Velocity and Attenuation Measurements

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    There is an international research effort to incorporate ceramic components into hot sections of heat engines. A major portion of this effort is directed towards the understanding and control of ceramic processing so that the strength of ceramics may be optimized. To date, the strength of sintered ceramics (e.g., SiC) is well below, by about two orders of magnitude, the theoretical strength [1,4]. This discrepancy is understood to be due to the presence of voids, inclusions, agglomerates, and anomalously large grains [4]. These defects, causing premature failure, are introduced or formed during the ceramic manufacturing process. Considerable work has already been done to remove these strength reducing material variations. This has resulted in a steady increase in the fracture strength of ceramics; however, the rate of this increase has slowed. Adding to the problem is the fact that the fracture strength of identically produced experimental samples varies as much as 35 percent [2]. As a result of the loss of momentum toward higher strengths, researchers are turning to ceramic- ceramic fiber composites. These composites show promise of increasing the fracture strength of ceramic materials even further. It is likely that the same material strength variations will be present, at least locally in the matrix, in ceramic composites

    Gauge and Supersymmetric Invariance of a Boundary Bagger-Lambert-Gustavsson Theory

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    In this paper we will discuss the effect of a having a boundary on the supersymmetric invariance and gauge invariance of the Bagger-Lambert-Gustavsson (BLG) Theory. We will show that even though the supersymmetry and gauge invariance of the original BLG theory is broken due to the presence of a boundary, it restored by the addition of suitable boundary terms. In fact, to achieve the gauge invariance of this theory, we will have to introduce new boundary degrees of freedom. The boundary theory obeyed by these new boundary degrees of freedom will be shown to be a generalization of the gauged Wess-Zumino-Witten model, with the generators of the Lie algebra replaced by the generators of the Lie 3-algebra. The gauge and supersymmetry variations of the boundary theory will exactly cancel the boundary terms generated by the gauge and supersymmetric variations of the bulk theory.Comment: 15 pages, 0 figures, accepted for publication in JHE

    N = 2 supersymmetric sigma-models and duality

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    For two families of four-dimensional off-shell N = 2 supersymmetric nonlinear sigma-models constructed originally in projective superspace, we develop their formulation in terms of N = 1 chiral superfields. Specifically, these theories are: (i) sigma-models on cotangent bundles T*M of arbitrary real analytic Kaehler manifolds M; (ii) general superconformal sigma-models described by weight-one polar supermultiplets. Using superspace techniques, we obtain a universal expression for the holomorphic symplectic two-form \omega^{(2,0)} which determines the second supersymmetry transformation and is associated with the two complex structures of the hyperkaehler space T*M that are complimentary to the one induced from M. This two-form is shown to coincide with the canonical holomorphic symplectic structure. In the case (ii), we demonstrate that \omega^{(2,0)} and the homothetic conformal Killing vector determine the explicit form of the superconformal transformations. At the heart of our construction is the duality (generalized Legendre transform) between off-shell N = 2 supersymmetric nonlinear sigma-models and their on-shell N = 1 chiral realizations. We finally present the most general N = 2 superconformal nonlinear sigma-model formulated in terms of N = 1 chiral superfields. The approach developed can naturally be generalized in order to describe 5D and 6D superconformal nonlinear sigma-models in 4D N = 1 superspace.Comment: 31 pages, no figures; V2: reference and comments added, typos corrected; V3: more typos corrected, published versio

    Extended supersymmetric sigma models in AdS_4 from projective superspace

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    There exist two superspace approaches to describe N=2 supersymmetric nonlinear sigma models in four-dimensional anti-de Sitter (AdS_4) space: (i) in terms of N=1 AdS chiral superfields, as developed in arXiv:1105.3111 and arXiv:1108.5290; and (ii) in terms of N=2 polar supermultiplets using the AdS projective-superspace techniques developed in arXiv:0807.3368. The virtue of the approach (i) is that it makes manifest the geometric properties of the N=2 supersymmetric sigma-models in AdS_4. The target space must be a non-compact hyperkahler manifold endowed with a Killing vector field which generates an SO(2) group of rotations on the two-sphere of complex structures. The power of the approach (ii) is that it allows us, in principle, to generate hyperkahler metrics as well as to address the problem of deformations of such metrics. Here we show how to relate the formulation (ii) to (i) by integrating out an infinite number of N=1 AdS auxiliary superfields and performing a superfield duality transformation. We also develop a novel description of the most general N=2 supersymmetric nonlinear sigma-model in AdS_4 in terms of chiral superfields on three-dimensional N=2 flat superspace without central charge. This superspace naturally originates from a conformally flat realization for the four-dimensional N=2 AdS superspace that makes use of Poincare coordinates for AdS_4. This novel formulation allows us to uncover several interesting geometric results.Comment: 88 pages; v3: typos corrected, version published in JHE

    Double In Situ Approach for the Preparation of Polymer Nanocomposite with Multi-functionality

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    A novel one-step synthetic route, the double in situ approach, is used to produce both TiO2nanoparticles and polymer (PET), and simultaneously forming a nanocomposite with multi-functionality. The method uses the release of water during esterification to hydrolyze titanium (IV) butoxide (Ti(OBu)4) forming nano-TiO2in the polymerization vessel. This new approach is of general significance in the preparation of polymer nanocomposites, and will lead to a new route in the synthesis of multi-functional polymer nanocomposites
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