Peeling fingers in an elastic Hele-Shaw channel

Using experiments and a depth-averaged numerical model, we study instabilities of two-phase flows in a Hele-Shaw channel with an elastic upper boundary and a non-uniform cross-section prescribed by initial collapse. Experimentally, we find increasingly complex and unsteady modes of air-finger propagation as the dimensionless bubble speed, Ca, and level of collapse are increased, including pointed fingers, indented fingers and the feathered modes first identified by Cuttle et al.(J. Fluid Mech., vol. 886, 2020, A20). By introducing a measure of the viscous contribution to finger propagation, we identify a Ca threshold beyond which viscous forces are superseded by elastic effects. Quantitative prediction of this transition between 'viscous' and 'elastic' reopening regimes across levels of collapse establishes the fidelity of the numerical model. In the viscous regime, we recover the non-monotonic dependence on Ca of the finger pressure, which is characteristic of benchtop models of airway reopening. To explore the elastic regime numerically, we extend the depth-averaged model introduced by Fontana et al. (J. Fluid Mech., vol. 916, 2021, A27) to include an artificial disjoining pressure which prevents the unphysical self-intersection of the interface. Using time simulations, we capture for the first time the majority of experimental finger dynamics, including feathered modes. We show that these disordered states continually evolve, with no evidence of convergence to steady or periodic states. We find that the steady bifurcation structure satisfactorily predicts the bubble pressure as a function of Ca, but that it does not provide sufficient information to predict the transition to unsteady dynamics which appears strongly nonlinear.Comment: 28 pages, 15 figure

Muscle fiber conduction velocity is more affected after eccentric than concentric exercise

It has been shown that mean muscle fiber conduction velocity (CV) can be acutely impaired after eccentric exercise. However, it is not known whether this applies to other exercise modes. Therefore, the purpose of this experiment was to compare the effects of eccentric and concentric exercises on CV, and amplitude and frequency content of surface electromyography (sEMG) signals up to 24 h post-exercise. Multichannel sEMG signals were recorded from biceps brachii muscle of the exercised arm during isometric maximal voluntary contraction (MVC) and electrically evoked contractions induced by motor-point stimulation before, immediately after and 2 h after maximal eccentric (ECC group, N = 12) and concentric (CON group, N = 12) elbow flexor exercises. Isometric MVC decreased in CON by 21.7 ± 12.0% (± SD, p < 0.01) and by 30.0 ± 17.7% (p < 0.001) in ECC immediately post-exercise when compared to baseline. At 2 h post-exercise, ECC showed a reduction in isometric MVC by 24.7 ± 13.7% (p < 0.01) when compared to baseline, while no significant reduction (by 8.0 ± 17.0%, ns) was observed in CON. Similarly, reduction in CV was observed only in ECC both during the isometric MVC (from baseline of 4.16 ± 0.3 to 3.43 ± 0.4 m/s, p < 0.001) and the electrically evoked contractions (from baseline of 4.33 ± 0.4 to 3.82 ± 0.3 m/s, p < 0.001). In conclusion, eccentric exercise can induce a greater and more prolonged reduction in muscle force production capability and CV than concentric exercis

Range of shoulder motion in patients with adhesive capsulitis; Intra-tester reproducibility is acceptable for group comparisons

<p>Abstract</p> <p>Background</p> <p>Measurements of range of motion play a key role in shoulder research. The purpose of this study is to investigate intra-observer reproducibility of measurements of active and passive range of motion in patients with adhesive capsulitis.</p> <p>Methods</p> <p>The study was carried out in a population consisting of 32 patients with clinical signs of adhesive capsulitis. A specified measurement protocol was used, and range of motion in affected and non-affected shoulders was measured twice for each patient with a one-week interval.</p> <p>Results</p> <p>For most of the investigated individual movements, test-retest differences in range of motion score of more than approximately 15° are not likely to occur as a result of measurement error only. Point-estimates for the intraclass correlation coefficient ranged from 0.61 to 0.93.</p> <p>Conclusion</p> <p>Range of motion of patients with adhesive capsulitis can be measured with acceptable reproducibility in settings where groups are compared. Scores for individual patients should be interpreted with caution.</p

Hydrodilatation, corticosteroids and adhesive capsulitis: A randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Hydrodilatation of the glenohumeral joint is by several authors reported to improve shoulder pain and range of motion for patients with adhesive capsulitis. Procedures described often involve the injection of corticosteroids, to which the reported treatment effects may be attributed. Any important contribution arising from the hydrodilatation procedure itself remains to be demonstrated.</p> <p>Methods</p> <p>In this randomized trial, a hydrodilatation procedure including corticosteroids was compared with the injection of corticosteroids without dilatation. Patients were given three injections with two-week intervals, and all injections were given under fluoroscopic guidance. Outcome measures were the Shoulder Pain and Disability Index (SPADI) and measures of active and passive range of motion. Seventy-six patients were included and groups were compared six weeks after treatment. The study was designed as an open trial.</p> <p>Results</p> <p>The groups showed a rather similar degree of improvement from baseline. According to a multiple regression analysis, the effect of dilatation was a mean improvement of 3 points (confidence interval: -5 to 11) on the SPADI 0–100 scale. T-tests did not demonstrate any significant between-group differences in range of motion.</p> <p>Conclusion</p> <p>This study did not identify any important treatment effects resulting from three hydrodilatations that included steroid compared with three steroid injections alone.</p> <p>Trial registration</p> <p>The study is registered in Current Controlled Trials with the registration number ISRCTN90567697.</p

Mortality among Patients with Cleared Hepatitis C Virus Infection Compared to the General Population: A Danish Nationwide Cohort Study

BACKGROUND: The increased mortality in HCV-infected individuals partly stems from viral damage to the liver and partly from risk-taking behaviours. We examined mortality in patients who cleared their HCV-infection, comparing it to that of the general population. We also addressed the question whether prognosis differed according to age, substance abuse (alcohol abuse and injection drug use) and comorbidity. METHODOLOGY/PRINCIPAL FINDINGS: Patients with cleared HCV-infection were categorized into one of 8 groups according to age (20-39 years or 40-69 years) and patient characteristics (no substance abuse/no comorbidity; substance abuse/no comorbidity; no substance abuse/comorbidity; and substance abuse/comorbidity). For each patient, 4 age- and gender-matched individuals without substance abuse or comorbidity were selected from the general population, comprising a total of 8 comparison cohorts. We analyzed 10-year survival and used stratified Cox Regression analysis to compute mortality rate ratios (MRRs), comparing mortality between the 8 patient groups and the comparison cohorts, adjusting for personal income. Among patients without substance abuse or comorbidity, those aged 40-69 years had the same mortality as the comparison cohort (10-year survival: 95% (95% confidence interval [CI]: 93%-97%), MRR: 1.3 (95% CI: 0.8-2.3)), whereas those aged 20-39 years had higher mortality than the comparison cohort (10-year survival: 93% versus 99%, MRR: 5.7 (95% CI: 2.3-14.0). For both age categories, substance abuse and comorbidity decreased survival and increased MRRs. Patients aged 40-69 years with substance abuse and comorbidity suffered from substantial mortality (MRR: 12.5 (95% CI: 5.1-30.6)). CONCLUSIONS: Mortality in patients aged 40-69 years with cleared HCV-infection is comparable to individuals without HCV, provided they have no substance abuse or comorbidity. Any substance abuse and/or comorbidity not captured in the registries used for our study could explain the increased mortality in patients aged 20-39 years without documented substance abuse or comorbidity