Objectives : The ABSORB cohort A trial using the bioresorbable everolimus‐eluting scaffold (BVS revision 1.0, Abbott Vascular) demonstrated a slightly higher acute recoil with BVS than with metallic stents. To reinforce the mechanical strength of the scaffold, the new BVS scaffold (revision 1.1) with modified strut design was developed and tested in the ABSORB cohort B trial. This study sought to evaluate and compare the in vivo acute scaffold recoil of the BVS revision 1.0 in ABSORB cohort A and the BVS revision 1.1 in ABSORB cohort B with the historical recoil of the XIENCE V® everolimus‐eluting metal stent (EES, SPIRIT I and II). Methods : In the ABSORB cohort B trial, 101 patients with one or two de‐novo lesions were enrolled at 10 sites. In ABSORB cohort A, 27 patients treated with a BVS 1.0 were analyzed and compared with EES. Acute absolute recoil, assessed by quantitative coronary angiography, was defined as the difference between mean diameter of the last inflated balloon at the highest pressure ( X ) and mean lumen diameter of the stent immediately after the last balloon deflation ( Y ). Acute percent recoil was defined as ( X ‐ Y )/ X and expressed as a percentage. Results : Out of 101 patients enrolled in the ABSORB cohort B trial, 88 patients are available for complete analysis of acute recoil. Absolute recoil of BVS 1.1 (0.19 ± 0.18 mm) was numerically higher than metallic EES (vs. 0.13 ± 0.21 mm) and similar to BVS 1.0 (0.20 ± 0.21 mm) but the differences did not reach statistical significance ( P = 0.40). The acute percent recoil demonstrated the same trend (EES: 4.3% ± 7.1%, BVS 1.0: 6.9% ± 7.0%, BVS 1.1: 6.7% ± 6.4%, P = 0.22). In the multivariate regression model, high balloon/artery ratio (>1.1) (OR 1.91 [1.34–2.71]) was the predictive for high absolute recoil (>0.27 mm) while (larger) preprocedural MLD was protective (OR 0.84 [0.72–0.99]). The stent/scaffold type was not a predictor of acute recoil. Conclusions : The average in vivo acute scaffold recoil of the BVS 1.1 is slightly higher than the metallic EES. However, the scaffold/stent type was not predictive of high acute recoil, while implantation in undersized vessels or usage of oversized devices might confound the results. © 2011 Wiley‐Liss, Inc.
No abstract is provided for this article.
An analytical model based on variational principles for a thin-walled stiffened plate subjected to axial compression is presented. A system of nonlinear differential and integral equations is derived and solved using numerical continuation. The results show that the system is susceptible to highly unstable local--global mode interaction after an initial instability is triggered. Moreover, snap-backs in the response showing sequential destabilization and restabilization, known as cellular buckling or snaking, arise. The analytical model is compared to static finite element models for joint conditions between the stiffener and the main plate that have significant rotational restraint. However, it is known from previous studies that the behaviour, where the same joint is insignificantly restrained rotationally, is captured better by an analytical approach than by standard finite element methods; the latter being unable to capture cellular buckling behaviour even though the phenomenon is clearly observed in laboratory experiments.
The hemodynamic effects of nisoldipine were investigated in 16 patients with suspected coronary artery disease who underwent routine cardiac catheterization. Nisoldipine was given intravenously in a dose of 6 μg/kg over 3 minutes and measurements made before and after drug administration during spontaneous and matched atrial paced heart rate. During sinus rhythm, nisoldipine produced a significant increase in heart rate (19%, p < 10−5). Left ventricular systolic pressure decreased 28% (p < 10−6) and left ventricular end-diastolic pressure did not change significantly (5%, difference not significant). Coronary sinus and great cardiac vein blood flow increased by 21% (p < 0.02) and 25% (p < 0.005), respectively, after nisoldipine administration. Simultaneously, mean aortic pressure decreased 33% (p < 10−6); consequently, the global and regional coronary vascular resistances decreased by 50% (p < 10−4). The decreases in global (−8%) and regional (−4%) myocardial oxygen consumption did not reach statistical significance. A 6% (not significant) increase in end-diastolic volume and an 11% (p < 0.002) decrease in end-systolic volume resulted in an increase of 21% in stroke volume (p < 10−4) with a consistent increase in ejection fraction (+16%, p < 10−5). Total systemic vascular resistance was reduced by 30% (p < 0.0002). During spontaneous heart rate and matched atrial pacing, the time constant of isovolumic relaxation as assessed by a biexponential model, was significantly shortened. The maximal velocity of isovolumic contraction after nisoldipine was administered remained higher (+12%, p < 0.02) at an identical paced heart rate. Thus, nisoldipine is a potent coronary and peripheral vasodilator. No negative inotropic effects were observed in the dosage used.
Formulae for determining the elastic buckling loads of structural steel rectangular hollow sections (RHS) subjected to concentrated transverse forces are presented herein. The predicted elastic buckling load is bounded by a theoretical lower bound, where only the material within the bearing length is mobilised, and a practical upper bound, where the adjacent material is mobilised to its maximum extent. The lower bound is the elastic buckling load of a wide plate with a width equal to the bearing length and a length equal to the web depth, while the upper bound is determined from finite element (FE) analyses of various representative loading scenarios. The level of mobilisation of adjacent material is quantified by introducing a coefficient ζ that is calibrated through FE analyses in the commercial package ABAQUS, with the rotational stiffness afforded to the webs by the flanges also being captured. The four loading scenarios defined in the North American Specification (NAS) and Australian/New Zealand Standard (AS/NZS) for the design of cold-formed steel structures, namely the Interior-Two-Flange (ITF), End-Two-Flange (ETF), Interior-One-Flange (IOF) and End-One-Flange (EOF) loading conditions, alongside their transitional cases, are considered. Rectangular hollow sections with a broad spectrum of cross-sectional geometric proportions and bearing lengths encompassing the aforementioned loading conditions are considered. It is found that the developed formulae for predicting the elastic buckling loads under concentrated transverse forces provide accurate results that are typically within 5% of the numerical values. Hence, the developed formulae can be employed as a convenient alternative to numerical methods in advanced structural design methodologies, such as the Direct Strength Method (DSM) and the Continuous Strength Method (CSM).
No abstract is provided for this article.
No abstract is provided for this article.
Long-acting bronchodilators are the most effective treatments currently available for managing patients with COPD.Long-acting muscarinic antagonists and β 2 -agonists are equally effective in producing bronchodilation, reducing symptoms, improving quality of life, and preventing exacerbations and are well tolerated.They probably work mainly by relaxing smooth muscle of peripheral airways to reduce gas trapping.Although both drug classes have non-bronchodilator effects that might be beneficial, this has not been clearly established in COPD patients.Remarkably, long-acting β 2 -agonists and long-acting muscarinic antagonists have additive bronchodilator effects, although this has not always translated into greater clinical benefit.Nevertheless, long-acting β 2 -agonist/long-acting muscarinic antagonist fixed-dose combinations are more effective than the single components and inhaled-corticosteroid/long-acting β 2 -agonist combinations.Although there is some rationale for triple therapy with long-acting β 2 -agonist/long-acting muscarinic antagonist/inhaled-corticosteroid, it remains to be shown that this would be more effective than long-acting β 2 -agonist/long-acting muscarinic antagonist combinations, although may be indicated for COPD patients with frequent exacerbations and with overlapping features with asthma, including increased blood eosinophils.It is unlikely that new classes of bronchodilators will be developed for COPD and what is needed is effective and safe antiinflammatory treatments.(BRN Rev.
We present SOFIA/HAWC+ continuum polarisation data on the magnetic fields threading 17 pc-scale massive molecular clumps at the western end of the $η$ Car GMC (Region 9 of CHaMP, representing all stages of star formation from pre-stellar to dispersing via feedback), revealing important details about the field morphology and role in the gas structures of this clump sample. We performed Davis-Chandrasekhar-Fermi and Histogram of Relative Orientation analyses tracing column densities 25.0 $<$ log($N$/m$^{-2}$) $<$ 27.2. With HRO, magnetic fields change from mostly parallel to column density structures to mostly perpendicular at a threshold $N_{\rm crit}$ = (3.7$\pm$0.6)$\times$10$^{26}$ m$^{-2}$, indicating that gravitational forces exceed magnetic forces above this value. The same analysis in 10 individual clumps gives similar results, with the same clear trend in field alignments and a threshold $N_{\rm crit}$ = (1.9$^{+1.5}_{-0.8}$)$\times$10$^{26}$ m$^{-2}$. In the other 7 clumps, the alignment trend with $N$ is much flatter or even reversed, inconsistent with the usual HRO pattern. Instead, these clumps' fields reflect external environmental forces, such as from the nearby HII region NGC 3324. DCF analysis reveals field strengths somewhat higher than typical of nearby clouds, with the $Bn$ data lying mostly above the Crutcher (2012) relation. The mass:flux ratio $λ$ across all clumps has a gaussian distribution, with log$λ_{\rm DCF}$ = -0.75$\pm$0.45 (mean$\pmσ$): only small areas are dominated by gravity. However, a significant trend of rising log$λ$ with falling $T_{\rm dust}$ parallels Pitts et al's (2019) result: $T_{\rm dust}$ falls as $N_{\rm H_2}$ rises towards clump centres. Thus, in this massive clump sample, magnetic fields provide enough support against gravity to explain their overall low star formation rate.
