Dynamic response of some tentative compliant wall structures to convected turbulence fields

Some tentative compliant wall structures designed for possible skin friction drag reduction are investigated. Among the structural models considered is a ribbed membrane backed by polyurethane or PVS plastisol. This model is simplified as a beam placed on a viscoelastic foundation as well as on a set of evenly spaced supports. The total length of the beam may be either finite or infinite, and the supports may be either rigid or elastic. Another structural model considered is a membrane mounted over a series of pretensioned wires, also evenly spaced, and the entire membrane is backed by an air cavity. The forcing pressure field is idealized as a frozen random pattern convected downstream at a characteristic velocity. The results are given in terms of the frequency response functions of the system, the spectral density of the structural motion, and the spectral density of the boundary layer pressure including the effect of structural motion. These results are used in a parametric study of structural configurations capable of generating favorable wave lengths, wave amplitudes, and wave speeds in the structural motion for potential drag reduction

Impact of Acute Rejection on Kidney Allograft Outcomes in Recipients on Rapid Steroid Withdrawal

Background. Our aim was to study the impact of clinical acute rejection (CR) and subclinical rejection (SR) on outcomes in kidney transplant recipients treated with rapid steroid withdrawal (RSW). Methods. All patients who received a living or deceased donor kidney transplant and were treated with RSW were included. The primary outcome was death-censored graft survival. Biopsies with Banff borderline changes were included with the rejection groups. Results. 457 kidney transplant recipients treated with RSW were included; 46 (10%) experienced SR, and 36 (7.8%) had CR. Mean HLA mismatch was significantly higher in the CR group. The Banff grade of rejection was higher in the CR group. There was a larger proportion of patients in both rejection groups with the combination of IFTA and persistent inflammation on the follow-up protocol biopsy done at 1 year. The estimated 5-year death-censored graft survival was 81% in SR, 78% in CR, and 97% in the control group (P < .0001). Significant differences were observed in allograft survival between the CR and control group (HR 9.06, 95% CI 3.39–24.2) and between the SR and control group (HR 4.22, 95% CI 1.30–13.7). Conclusion. Both SR and CR are associated with an inferior graft survival in recipients on RSW

Trends in Outcomes for Neonates Born Very Preterm and Very Low Birth Weight in 11 High-Income Countries

Objective To evaluate outcome trends of neonates born very preterm in 11 high-income countries participating in the International Network for Evaluating Outcomes of neonates. Study design In a retrospective cohort study, we included 154 233 neonates admitted to 529 neonatal units between January 1, 2007, and December 31, 2015, at 24(0/7) to 31(6/7) weeks of gestational age and birth weight <1500 g. Composite outcomes were in-hospital mortality or any of severe neurologic injury, treated retinopathy of prematurity, and bronchopulmonary dysplasia (BPD); and same composite outcome excluding BPD. Secondary outcomes were mortality and individual morbidities. For each country, annual outcome trends and adjusted relative risks comparing epoch 2 (2012-2015) to epoch 1 (2007-2011) were analyzed. Results For composite outcome including BPD, the trend decreased in Canada and Israel but increased in Australia and New Zealand, Japan, Spain, Sweden, and the United Kingdom. For composite outcome excluding BPD, the trend decreased in all countries except Spain, Sweden, Tuscany, and the United Kingdom. The risk of composite outcome was lower in epoch 2 than epoch 1 in Canada (adjusted relative risks 0.78; 95% CI 0.74-0.82) only. The risk of composite outcome excluding BPD was significantly lower in epoch 2 compared with epoch 1 in Australia and New Zealand, Canada, Finland, Japan, and Switzerland. Mortality rates reduced in most countries in epoch 2. BPD rates increased significantly in all countries except Canada, Israel, Finland, and Tuscany. Conclusions In most countries, mortality decreased whereas BPD increased for neonates born very preterm

Clinical Study Impact of Acute Rejection on Kidney Allograft Outcomes in Recipients on Rapid Steroid Withdrawal

Background. Our aim was to study the impact of clinical acute rejection (CR) and subclinical rejection (SR) on outcomes in kidney transplant recipients treated with rapid steroid withdrawal (RSW). Methods. All patients who received a living or deceased donor kidney transplant and were treated with RSW were included. The primary outcome was death-censored graft survival. Biopsies with Banff borderline changes were included with the rejection groups. Results. 457 kidney transplant recipients treated with RSW were included; 46 (10%) experienced SR, and 36 (7.8%) had CR. Mean HLA mismatch was significantly higher in the CR group. The Banff grade of rejection was higher in the CR group. There was a larger proportion of patients in both rejection groups with the combination of IFTA and persistent inflammation on the follow-up protocol biopsy done at 1 year. The estimated 5-year death-censored graft survival was 81% in SR, 78% in CR, and 97% in the control group (P &lt; .0001). Significant differences were observed in allograft survival between the CR and control group (HR 9.06, and between the SR and control group (HR 4.22, 95% CI 1.30-13.7). Conclusion. Both SR and CR are associated with an inferior graft survival in recipients on RSW