198 research outputs found

    A Weighted Estimate for the Square Function on the Unit Ball in \C^n

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    We show that the Lusin area integral or the square function on the unit ball of \C^n, regarded as an operator in weighted space L2(w)L^2(w) has a linear bound in terms of the invariant A2A_2 characteristic of the weight. We show a dimension-free estimate for the ``area-integral'' associated to the weighted L2(w)L^2(w) norm of the square function. We prove the equivalence of the classical and the invariant A2A_2 classes.Comment: 11 pages, to appear in Arkiv for Matemati

    National Football League Skilled and Unskilled Positions Vary in Opportunity and Yield in Return to Play After an Anterior Cruciate Ligament Injury.

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    BACKGROUND: Anterior cruciate ligament (ACL) injuries pose a significant risk to the careers of players in the National Football League (NFL). The relationships between draft round and position on return to play (RTP) among NFL players are not well understood, and the ability to return to preinjury performance levels remains unknown for most positions. PURPOSE: To test for differences in RTP rates and changes in performance after an ACL injury by position and draft round. We hypothesized that skilled positions would return at a lower rate compared to unskilled positions. We further hypothesized that early draft-round status would relate to a greater rate of RTP and that skilled positions and a lower draft round would correlate with decreased performance for players who return to sport. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Utilizing a previously established database of publicly available information regarding ACL tears among NFL players, athletes with ACL tears occurring between the 2010 and 2013 seasons were identified. Generalized linear models and Kaplan-Meier time-to-event models were used to test the study hypotheses. RESULTS: The overall RTP rate was 61.7%, with skilled players and unskilled players returning at rates of 64.1% and 60.4%, respectively (P = .74). Early draft-round players and unskilled late draft-round players had greater rates of RTP compared to skilled late draft-round players and both unskilled and skilled undrafted free agents (UDFAs). Skilled early draft-round players constituted the only cohort that played significantly fewer games after an injury. Unskilled UDFAs constituted the only cohort to show a significant increase in the number of games started and ratio of games started to games played, starting more games in which they played, after an injury. CONCLUSION: Early draft-round and unskilled players were more likely to return compared to their later draft-round and skilled peers. Skilled early draft-round players, who displayed relatively high rates of RTP, constituted the only cohort to show a decline in performance. Unskilled UDFAs, who exhibited relatively low rates of RTP, constituted the only cohort to show an increase in performance. The significant effect of draft round and position type on RTP may be caused by a combination of differences in talent levels and in opportunities given to returning to play

    Short-term (<8 weeks) high-intensity interval training in diseased cohorts

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    Background & Aim: Exercise training regimes can lead to improvements in measures of cardiorespiratory fitness (CRF), improved general health, and reduced morbidity and overall mortality risk. High intensity interval training (HIIT) offers a time-efficient approach to improve CRF in healthy individuals, but the relative benefits of HIIT compared to traditional training methods are unknown in across different disease cohorts. Methods: This systematic review and meta-analysis compares CRF gains in randomised controlled trials of short-term (<8 weeks) HIIT vs. either no exercise control (CON) or moderate continuous exercise training (MCT) within diseased cohorts. Literature searches of the following databases were performed: MEDLINE, EMBASE, CINAHL, AMED, and PubMed (all from inception to 1st December 2017), with further searches of Clinicaltrials.gov and citations via Google Scholar. Primary outcomes were effect upon CRF variables; VO2peak and Anaerobic Threshold (AT). Results: Thirty-nine studies met the inclusion criteria. HIIT resulted in a clinically significant increase in VO2peak compared with CON (mean difference (MD) 3.32 ml∙kg-1∙min-1; 95% CI 2.56 to 2.08). Overall HIIT provided added benefit to VO2peak over MCT (MD 0.79 ml∙kg-1∙min-1; 95% CI 0.20 to 1.39). The benefit of HIIT was most marked in patients with cardiovascular disease when compared to MCT (VO2peak (MD 1.66 ml∙kg-1∙min-1; 95% CI 0.60 to 2.73); AT (MD 1.61 ml∙kg-1∙min-1; 95% CI 0.33 to 2.90)). Conclusions: HIIT elicits improvements in objective measures of CRF within 8 weeks in diseased cohorts compared to no intervention. When compared to MCT, HIIT imparts statistically significant additional improvements in measures of CRF, with clinically important additional improvements in VO2peak in cardiovascular patients. Comparative efficacy of HIIT vs MCT combined with an often reduced time commitment may warrant HIIT’s promotion as a viable clinical exercise intervention

    Short-term (less 8 wk) high-intensity interval training in diseased cohorts

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    Background and Aim: Exercise training regimes can lead to improvements in measures of cardiorespiratory fitness (CRF), improved general health, and reduced morbidity and overall mortality risk. High-intensity interval training (HIIT) offers a time-efficient approach to improve CRF in healthy individuals, but the relative benefits of HIIT compared with traditional training methods are unknown in across different disease cohorts. Methods: This systematic review and meta-analysis compares CRF gains in randomized controlled trials of short-term (G8 wk) HIIT versus either no exercise control (CON) or moderate continuous training (MCT) within diseased cohorts. Literature searches of the following databases were performed: MEDLINE, EMBASE, CINAHL, AMED, and PubMed (all from inception to December 1, 2017), with further searches of Clinicaltrials.gov and citations via Google Scholar.Primary outcomes were effect on CRF variables: V˙ O2peak and anaerobic threshold. Results: Thirty-nine studies met the inclusion criteria. HIIT resulted in a clinically significant increase in V˙ O2peak compared with CON (mean difference [MD] = 3.32 mLIkgj1 Iminj1, 95% confidence interval [CI] = 2.56–2.08). Overall HIIT provided added benefit to V˙ O2peak over MCT (MD = 0.79 mLIkgj1 Iminj1, 95% CI =0.20–1.39). The benefit of HIIT was most marked in patients with cardiovascular disease when compared with MCT (V˙ O2peak: MD =1.66 mLIkgj1 Iminj1, 95% CI = 0.60–2.73; anaerobic threshold: MD = 1.61 mLIkgj1 Iminj1, 95% CI = 0.33–2.90). Conclusions: HIIT elicits improvements in objective measures of CRF within 8 wk in diseased cohorts compared with no intervention. When compared with MCT, HIIT imparts statistically significant additional improvements in measures of CRF, with clinically important additional improvements in V˙ O2peak in cardiovascular patients. Comparative efficacy of HIIT versus MCT combined with an often reduced time commitment may warrant HIIT_s promotion as a viable clinical exercise intervention

    Exercise and other nonpharmacological strategies to reduce blood pressure in older adults: a systematic review and meta-analysis

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    The incidence of hypertension increases with advancing age and represents a significant burden of disease. Lifestyle modification represents the first-line intervention in treatment algorithms; however, the majority of evidence for this comes from studies involving young participants using interventions that may not always be feasible in the elderly. This manuscript presents a systematic review of all randomized controlled trials involving participants with a mean age of 65 or over investigating nonpharmacological strategies to reduce blood pressure (BP). Fifty-three randomized controlled trials were included. The majority of interventions described aerobic exercise training, dynamic resistance exercise training, or combined aerobic and dynamic resistance exercise training (COM), with limited studies reporting isometric exercise training or alternative lifestyle strategies. Aerobic exercise training, dynamic resistance exercise training, COM, and isometric exercise training all elicited significant reductions in both systolic and diastolic BP, with no additional benefit of COM compared with single modality exercise training. Three months of traditional exercise-based lifestyle intervention may produce a reduction in BP of approximately 5 mmHg systolic and 3 mmHg diastolic in older individuals, similar to that expected in younger individuals

    Short-term (<8 weeks) high-intensity interval training in diseased cohorts

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    Background & Aim: Exercise training regimes can lead to improvements in measures of cardiorespiratory fitness (CRF), improved general health, and reduced morbidity and overall mortality risk. High intensity interval training (HIIT) offers a time-efficient approach to improve CRF in healthy individuals, but the relative benefits of HIIT compared to traditional training methods are unknown in across different disease cohorts. Methods: This systematic review and meta-analysis compares CRF gains in randomised controlled trials of short-term (<8 weeks) HIIT vs. either no exercise control (CON) or moderate continuous exercise training (MCT) within diseased cohorts. Literature searches of the following databases were performed: MEDLINE, EMBASE, CINAHL, AMED, and PubMed (all from inception to 1st December 2017), with further searches of Clinicaltrials.gov and citations via Google Scholar. Primary outcomes were effect upon CRF variables; VO2peak and Anaerobic Threshold (AT). Results: Thirty-nine studies met the inclusion criteria. HIIT resulted in a clinically significant increase in VO2peak compared with CON (mean difference (MD) 3.32 ml∙kg-1∙min-1; 95% CI 2.56 to 2.08). Overall HIIT provided added benefit to VO2peak over MCT (MD 0.79 ml∙kg-1∙min-1; 95% CI 0.20 to 1.39). The benefit of HIIT was most marked in patients with cardiovascular disease when compared to MCT (VO2peak (MD 1.66 ml∙kg-1∙min-1; 95% CI 0.60 to 2.73); AT (MD 1.61 ml∙kg-1∙min-1; 95% CI 0.33 to 2.90)). Conclusions: HIIT elicits improvements in objective measures of CRF within 8 weeks in diseased cohorts compared to no intervention. When compared to MCT, HIIT imparts statistically significant additional improvements in measures of CRF, with clinically important additional improvements in VO2peak in cardiovascular patients. Comparative efficacy of HIIT vs MCT combined with an often reduced time commitment may warrant HIIT’s promotion as a viable clinical exercise intervention

    Transverse lattice calculation of the pion light-cone wavefunctions

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    We calculate the light-cone wavefunctions of the pion by solving the meson boundstate problem in a coarse transverse lattice gauge theory using DLCQ. A large-N_c approximation is made and the light-cone Hamiltonian expanded in massive dynamical fields at fixed lattice spacing. In contrast to earlier calculations, we include contributions from states containing many gluonic link-fields between the quarks.The Hamiltonian is renormalised by a combination of covariance conditions on boundstates and fitting the physical masses M_rho and M_pi, decay constant f_pi, and the string tension sigma. Good covariance is obtained for the lightest 0^{-+} state, which we identify with the pion. Many observables can be deduced from its light-cone wavefunctions.After perturbative evolution,the quark valence structure function is found to be consistent with the experimental structure function deduced from Drell-Yan pi-nucleon data in the valence region x > 0.5. In addition, the pion distribution amplitude is consistent with the experimental distribution deduced from the pi gamma^* gamma transition form factor and diffractive dissociation. A new observable we calculate is the probability for quark helicity correlation. We find a 45% probability that the valence-quark helicities are aligned in the pion.Comment: 27 pages, 9 figure

    Considerations on equity in management of end-stage kidney disease in low- and middle-income countries

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    Achievement of equity in health requires development of a health system in which everyone has a fair opportunity to attain their full health potential. The current, large country-level variation in the reported incidence and prevalence of treated end-stage kidney disease indicates the existence of system-level inequities. Equitable implementation of kidney replacement therapy (KRT) programs must address issues of availability, affordability, and acceptability. The major structural factors that impact equity in KRT in different countries are the organization of health systems, overall health care spending, funding and delivery models, and nature of KRT prioritization (transplantation, hemodialysis or peritoneal dialysis, and conservative care). Implementation of KRT programs has the potential to exacerbate inequity unless equity is deliberately addressed. In this review, we summarize discussions on equitable provision of KRT in low- and middle-income countries and suggest areas for future research

    Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

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    The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR
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