521 research outputs found

    Stress, coping, coping effectiveness and emotions in Malaysian elite tenpin bowlers: Role of context and importance.

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    Professional tenpin bowlers were examined for their stressors experienced, coping, coping effectiveness and emotional reactions prior to and during minor and major competitions. Fifteen tenpin bowlers (male n = 6; female n = 9) completed a diary pack on three separate periods: one minor competition period and two major competitions periods. Tenpin bowlers completed a diary to report their stressor encounters, coping strategies, coping effectiveness, resulting emotions and their intensity on a daily basis. Results showed that the tenpin bowlers experienced a limited (n = 5) number of stressors over time which accounted for 95% of the stressors reported, almost similar to those observed in Caucasian athletes. However, unlike Caucasian athletes our sample reported a similar number of positive and negative emotions. Context (training vs. competitions) and the importance of the competition were found to influence stress and coping process especially at the level of individual stressors. Findings suggest a need to further examine cultural similarities and differences in the stress, coping and emotion process among athletes to prevent misunderstanding and miscommunication. This will allow the development interventions which are not only situation and context specific but also culturally sensitive

    A Phase I Trial of Aminolevulinic Acid-Photodynamic Therapy for Treatment of Oral Leukoplakia

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    Background Photodynamic therapy with aminolevulinic acid (ALA PDT) for oral leukoplakia has shown promising effects in regression of oral leukoplakia. Although ALA has been extensively studied and is an ideal photosensitizer, the optimal light dose for treatment of oral leukoplakia has not been determined. We conducted a phase I study to determine MTD and DLT of PDT in patients treated with ALA for leukoplakia. Methods Patients with histologically confirmed oral leukoplakia received a single treatment of ALA PDT in cohorts with escalating doses of light (585 nm). Clinical, histologic, and biologic markers were assessed. Results Analysis of 11 participants is reported. No significant toxicity from ALA PDT was observed in patients who received ALA with a light dose of up to 4 J/cm2. One participant experienced transient grade 3 transaminase elevation due to ALA. One participant had a partial clinical response 3 months after treatment. Biologic mucosal risk markers showed no significant associations. Determination of MTD could not be accomplished within a feasible timeframe for completion of the study. Conclusions ALA PDT could be safely administered with a light dose up to 4 J/cm2 and demonstrated activity. Larger studies are needed to fully elucidate the MTD and efficacy of ALA-PDT

    Number of distinct sites visited by N random walkers on a Euclidean lattice

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    The evaluation of the average number S_N(t) of distinct sites visited up to time t by N independent random walkers all starting from the same origin on an Euclidean lattice is addressed. We find that, for the nontrivial time regime and for large N, S_N(t) \approx \hat S_N(t) (1-\Delta), where \hat S_N(t) is the volume of a hypersphere of radius (4Dt \ln N)^{1/2}, \Delta={1/2}\sum_{n=1}^\infty \ln^{-n} N \sum_{m=0}^n s_m^{(n)} \ln^{m} \ln N, d is the dimension of the lattice, and the coefficients s_m^{(n)} depend on the dimension and time. The first three terms of these series are calculated explicitly and the resulting expressions are compared with other approximations and with simulation results for dimensions 1, 2, and 3. Some implications of these results on the geometry of the set of visited sites are discussed.Comment: 15 pages (RevTex), 4 figures (eps); to appear in Phys. Rev.

    Single- and multi-walled carbon nanotubes viewed as elastic tubes with Young's moduli dependent on layer number

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    The complete energy expression of a deformed single-walled carbon nanotube (SWNT) is derived in the continuum limit from the local density approximation model proposed by Lenosky {\it et al.} \lbrack Nature (London) {\bf 355}, 333 (1992)\rbrack and shows to be content with the classic shell theory by which the Young's modulus, the Poisson ratio and the effective wall thickness of SWNTs are obtained as Y=4.70Y=4.70TPa, ν=0.34\nu=0.34, h=0.75A˚h=0.75{\rm \AA}, respectively. The elasticity of a multi-walled carbon nanotube (MWNT) is investigated as the combination of the above SWNTs of layer distance d=3.4A˚d=3.4 {\rm \AA} and the Young's modulus of the MWNT is found to be an apparent function of the number of layers, NN, varying from 4.70TPa to 1.04TPa for N=1 to \infty.Comment: 4 pages, 1 figur

    Predictive approaches to heterogeneous treatment effects: a scoping review

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    Background: Recent evidence suggests that there is often substantial variation in the benefits and harms across a trial population. We aimed to identify regression modeling approaches that assess heterogeneity of treatment effect within a randomized clinical trial. Methods: We performed a literature review using a broad search strategy, complemented by suggestions of a technical expert panel. Results: The approaches are classified into 3 categories: 1) Risk-based methods (11 papers) use only prognostic factors to define patient subgroups, relying on the mathematical dependency of the absolute risk difference on baseline risk; 2) Treatment effect modeling methods (9 papers) use both prognostic factors and treatment effect modifiers to explore characteristics that interact with the effects of therapy on a relative scale. These methods couple data-driven subgroup identification with approaches to prevent overfitting, such as penalization or use of separate data sets for subgroup identification and effect estimation. 3) Optimal treatment regime methods (12 papers) focus primarily on treatment effect modifiers to classify the trial population into those who benefit from treatment and those who do not. Finally, we also identified papers which describe model evaluation methods (4 papers). Conclusions: Three classes of approaches were identified to assess heterogeneity of treatment effect. Methodological research, including both simulations and empirical evaluations, is required to compare the available methods in different settings and to derive well-informed guidance for their application in RCT analysis

    Inflation and late time acceleration in braneworld cosmological models with varying brane tension

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    Braneworld models with variable brane tension λ\lambda introduce a new degree of freedom that allows for evolving gravitational and cosmological constants, the latter being a natural candidate for dark energy. We consider a thermodynamic interpretation of the varying brane tension models, by showing that the field equations with variable λ\lambda can be interpreted as describing matter creation in a cosmological framework. The particle creation rate is determined by the variation rate of the brane tension, as well as by the brane-bulk energy-matter transfer rate. We investigate the effect of a variable brane tension on the cosmological evolution of the Universe, in the framework of a particular model in which the brane tension is an exponentially dependent function of the scale factor. The resulting cosmology shows the presence of an initial inflationary expansion, followed by a decelerating phase, and by a smooth transition towards a late accelerated de Sitter type expansion. The varying brane tension is also responsible for the generation of the matter in the Universe (reheating period). The physical constraints on the model parameters, resulted from the observational cosmological data, are also investigated.Comment: 25 pages, 8 figures, accepted for publication in European Physical Journal

    MRI vastus lateralis fat fraction predicts loss of ambulation in Duchenne muscular dystrophy

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    ObjectiveWe studied the potential of quantitative MRI (qMRI) as a surrogate endpoint in Duchennemuscular dystrophy by assessing the additive predictive value of vastus lateralis (VL) fat fraction(FF) to age on loss of ambulation (LoA).MethodsVL FFs were determined on longitudinal Dixon MRI scans from 2 natural history studies inLeiden University Medical Center (LUMC) and Cincinnati Children’s Hospital MedicalCenter (CCHMC). CCHMC included ambulant patients, while LUMC included a mixedambulant and nonambulant population. We fitted longitudinal VL FF values to a sigmoidalcurve using a mixed model with random slope to predict individual trajectories. The additivevalue of VL FF over age to predict LoA was calculated from a Cox model, yielding a hazard ratio.ResultsEighty-nine MRIs of 19 LUMC and 15 CCHMC patients were included. At similar age,6-minute walking test distances were smaller and VL FFs were correspondingly higher inLUMC compared to CCHMC patients. Hazard ratio of a percent-point increase in VL FF forthe time to LoA was 1.15 for LUMC (95% confidence interval [CI] 1.05–1.26; p = 0.003) and0.96 for CCHMC (95% CI 0.84–1.10; p = 0.569).ConclusionsThe hazard ratio of 1.15 corresponds to a 4.11-fold increase of the instantaneous risk of LoA inpatients with a 10% higher VL FF at any age. Although results should be confirmed in a largercohort with prospective determination of the clinical endpoint, this added predictive value ofVL FF to age on LoA supports the use of qMRI FF as an endpoint or stratification tool inclinical trials.Development and application of statistical models for medical scientific researc
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