6,526 research outputs found

    Use of an audio-paced incremental swimming test in young national-level swimmers

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    Purpose:To evaluate the reliability and sensitivity to training of an audio-paced incremental swimming test.Methods:Eight young national-level male swimmers (age 15 ± 1 year) performed a 7 × 200-m incremental swimming test (velocities 1.19, 1.24, 1.28, 1.33, 1.39, and 1.45 m/s and maximal sprint pace) using an audio-pacing device. The same test was performed 4 times by each participant, 1 wk apart to assess reliability (WK1, WK2) and after 9 and 20 wk of training (WK9, WK20). Blood lactate concentration ([La−]) and heart rate (HR) were recorded after each stage. Outcome measures were the velocity (v) and HR at lactate markers of 2 mM, 4 mM, and Δ1 mM.Results:Velocities at the lactate markers proved to be more reliable than HR, with typical errors ranging from 0.66% to 2.30% and 1.28% to 4.50%, respectively (shifts in mean ranged –0.91% to 0.73% and –0.84% to 1.79%, respectively). Across WK1, WK9, and WK20 there were significant improvements in peak velocity (P &lt; .001) and each of the velocities associated with the lactate markers (P &lt; .05), whereas only HR at Δ1 mM improved (P &lt; .05).Conclusions:This article demonstrates that an audio-paced incremental swimming test is reliable for use with junior swimmers and is sensitive to changes observed after training. The postswimming measurement of HR in the pool was comparatively less reliable.</jats:sec

    Quantum Critical Behavior in Kondo Systems

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    This article briefly reviews three topics related to the quantum critical behavior of certain heavy-fermion systems. First, we summarize an extended dynamical mean-field theory for the Kondo lattice, which treats on an equal footing the quantum fluctuations associated with the Kondo and RKKY couplings. The dynamical mean-field equations describe an effective Kondo impurity model with an additional coupling to vector bosons. Two types of quantum phase transition appear to be possible within this approach---the first a conventional spin-density-wave transition, the second driven by local physics. For the second type of transition to be realized, the effective impurity model must have a quantum critical point exhibiting an anomalous local spin susceptibility. In the second part of the paper, such a critical point is shown to occur in two variants of the Kondo impurity problem. Finally, we propose an operational test for the existence of quantum critical behavior driven by local physics. Neutron scattering results suggest that CeCu6x_{6-x}Aux_x passes this test.Comment: 6 pages, 4 eps figures, REVTeX (epsf style

    Clinical course and prognostic factors following bone recurrence from breast cancer.

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    Three hundred and sixty-seven women presenting to the Breast Unit at Guy's Hospital between 1975 and 1990 whose first distant metastasis was in the skeleton were identified and the influence of a number of patient and tumour characteristics on the development and subsequent prognosis of bone metastases was assessed. One hundred and thirty-nine women had disease that remained clinically confined to the skeleton. They were more likely to be older, with lobular carcinoma and to have presented initially with little or no axillary lymph node involvement. The 228 women who subsequently developed disease at extra-osseus sites were more likely to have poorly differentiated ductal tumours and heavy lymph node involvement at primary diagnosis. On multivariate analysis, the clinical and pathological factors of greatest prognostic importance for survival after the development of bone metastases were histological grade (P = < 0.0001), oestrogen receptor status (P = < 0.0001), bone disease at initial presentation (P = < 0.0001), disease-free interval (P = 0.002) and age (P = 0.006)

    Probabilistic Approach to Time-Dependent Load-Transfer Models of Fracture

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    A probabilistic method for solving time-dependent load-transfer models of fracture is developed. It is applicable to any rule of load redistribution, i.e, local, hierarchical, etc. In the new method, the fluctuations are generated during the breaking process (annealed randomness) while in the usual method, the random lifetimes are fixed at the beginning (quenched disorder). Both approaches are equivalent.Comment: 13 pages, 4 figures. To appear in Phys.Rev.

    Identification of host transcriptional networks showing concentration-dependent regulation by HPV16 E6 and E7 proteins in basal cervical squamous epithelial cells.

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    Development of cervical squamous cell carcinoma requires increased expression of the major high-risk human-papillomavirus (HPV) oncogenes E6 and E7 in basal cervical epithelial cells. We used a systems biology approach to identify host transcriptional networks in such cells and study the concentration-dependent changes produced by HPV16-E6 and -E7 oncoproteins. We investigated sample sets derived from the W12 model of cervical neoplastic progression, for which high quality phenotype/genotype data were available. We defined a gene co-expression matrix containing a small number of highly-connected hub nodes that controlled large numbers of downstream genes (regulons), indicating the scale-free nature of host gene co-expression in W12. We identified a small number of 'master regulators' for which downstream effector genes were significantly associated with protein levels of HPV16 E6 (n = 7) or HPV16 E7 (n = 5). We validated our data by depleting E6/E7 in relevant cells and by functional analysis of selected genes in vitro. We conclude that the network of transcriptional interactions in HPV16-infected basal-type cervical epithelium is regulated in a concentration-dependent manner by E6/E7, via a limited number of central master-regulators. These effects are likely to be significant in cervical carcinogenesis, where there is competitive selection of cells with elevated expression of virus oncoproteins.Cancer Research UK (Programme Grant A13080)This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/srep2983

    Effects of environmental exposure on cryogenic thermal insulation materials

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    Investigation was made to optimize selection of insulation materials for reusable space vehicles which will be repeatedly operated over periods of up to ten years. Results of study are summarized in two reports. Volume I describes tests and significant findings. In Volume II, extensive test data obtained are organized in handbook form

    clinical status and evolution in moyamoya which angiographic findings correlate

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    Abstract Moyamoya is a progressive steno-occlusive cerebrovascular pathology of unknown aetiology that usually involves the terminal portions of the internal carotid arteries and/or the proximal portions of the anterior and middle cerebral arteries bilaterally. The pre-operative Suzuki staging system and post-operative Matsushima grade are nearly universally used markers of natural history and surgical revascularization results, respectively, but their correlation with clinical and radiographic manifestations of moyamoya has not been systematically evaluated in a large cohort. This study evaluated the strength of correlations between pre- and post-operative angiographic parameters and clinical status among paediatric patients with moyamoya. The participants included 58 patients of mean age 11 years at the time of surgery who underwent bilateral indirect revascularization in the same procedure at Boston Children's Hospital, between January 2010 and December 2015. All included patients had available pre-operative and 1-year post-operative digital subtraction angiography. Clinical data included presenting symptoms, degree of functional incapacity, and peri-operative and long-term complications. Radiographic data included pre-operative Suzuki stage, degree of arterial stenosis, a novel collateral score, the presence of hypovascular territories on digital subtraction angiography, and post-operative Matsushima grade and evolution of stenosis. Chi-squared test and Pearson coefficient were used for correlation studies for categorical variables and Spearman's rho was used for correlation studies for continuous variables. Results showed that Suzuki stage, collateral score and degree of stenosis were insufficient to predict clinical presentation, pre-operative incapacity and radiographic presentation, whereas the presence of hypovascular territories was correlated with all of these. At 1-year follow-up, Matsushima grade was insufficient for predicting peri-operative or long-term complications, nor did it correlate with post-operative incapacity. The presence of hypovascular territories at 1-year follow-up was correlated with the incidence of post-operative ischaemic symptoms

    Performance measures in three rounds of the English bowel cancer screening pilot

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    OBJECTIVES: To compare performance measures across all three rounds of the English bowel cancer screening faecal occult blood test pilot and their relation to social deprivation and ethnicity. METHODS: In each round in three primary care trusts, data for a restricted population of over 48 500 aged 60–69 years were analysed. Individual-based data included postcode linked to area-based data on the Index of Multiple Deprivation (IMD) 2004, and ethnicity. Outcomes were the rates of screening and colonoscopy uptake, positivity and detection of neoplasia (adenomas or bowel cancer) and bowel cancer, and the positive predictive values (PPVs) of a positive test for neoplasia and bowel cancer. Sensitivity was calculated by the proportional incidence method using data on interval cancers identified from cancer registrations. RESULTS: The overall uptake rate was 61.8%, 57.0% and 58.7% in the first, second and third rounds, respectively. Although the PPV for cancer decreased over the course of the three rounds (10.9% in the 1st round, 6.5% in 3rd round), the PPV for all neoplasia remained relatively constant (42.6% in 1st round, 36.9% in 3rd round). Deprivation and non-white ethnic background (principally Indian subcontinent in the pilot region) were associated with low screening and colonoscopy uptake rates, and this changed little over the three screening rounds. Uptake was lower in men, although differences in uptake between men and women decreased over time. Non-participation in previous rounds was a strong predictor of low uptake. CONCLUSIONS: Performance measures are commensurate with expectations in a screening programme reaching its third round of screening, but a substantial ongoing effort is needed, particularly to address the effects of deprivation and ethnicity in relation to uptake
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