No abstract is provided for this article.
The concept and structural benefits of prestressing cold-formed steel beams are explored in the present paper. In the proposed system, prestressing is applied by means of a high-strength steel cable located within the cross section of the beam at an eccentric location with respect to the strong geometric axis. The internal forces generated by the prestressing are opposite in sign to those induced under subsequent vertical loading. Hence, the development of detrimental compressive stresses within the top region of the cold-formed steel beam is delayed and thus the load-carrying capacity of the beam is enhanced. Owing to the precamber that is induced along the member during the prestressing stage, the overall deflections of the beam are also reduced significantly. In the present paper, finite-element (FE) modeling was employed to simulate the mechanical behavior of prestressed cold-formed steel beams during the prestressing and vertical loading stages. Following the validation of the FE modeling approach, a set of parametric studies was conducted, where the influence of the key controlling parameters on the structural benefits obtained from the prestressing process was investigated. The parametric results were utilized to determine how the benefits obtained from the addition of the prestressed cable can be maximized, demonstrating the significant enhancements in the performance of the cold-formed steel beam that can be achieved.
The bioresorbable vascular stent (BVS) is totally translucent and radiolucent, leading to challenges when using conventional invasive imaging modalities. Agreement between quantitative coronary angiography (QCA), intravascular ultrasound (IVUS) and optical coherence tomography (OCT) in the BVS is unknown. Forty five patients enrolled in the ABSORB cohort B1 study underwent coronary angiography, IVUS and OCT immediately post BVS implantation, and at 6 months. OCT estimated stent length accurately compared to nominal length (95% CI of the difference: -0.19; 0.37 and -0.15; 0.47 mm(2) for baseline and 6 months, respectively), whereas QCA incurred consistent underestimation of the same magnitude at both time points (Pearson correlation = 0.806). IVUS yielded low accuracy (95% CI of the difference: 0.77; 3.74 and -1.15; 3.27 mm(2) for baseline and 6 months, respectively), with several outliers and random variability test-retest. Minimal lumen area (MLA) decreased substantially between baseline and 6 months on QCA and OCT and only minimally on IVUS (95% CI: 0.11; 0.42). Agreement between the different imaging modalities is poor: worst agreement Videodensitometry-IVUS post-implantation (ICCa 0.289); best agreement IVUS-OCT at baseline (ICCa 0.767). All pairs deviated significantly from linearity (P < 0.01). Passing-Bablok non-parametric orthogonal regression showed constant and proportional bias between IVUS and OCT. OCT is the most accurate technique for measuring stent length, whilst QCA incurs systematic underestimation (foreshortening) and solid state IVUS incurs random error. Volumetric calculations using solid state IVUS are therefore not reliable. There is poor agreement for MLA estimation between all the imaging modalities studied, including IVUS-OCT, hence their values are not interchangeable.
Although most attention has been focused on the drugs used to control asthma, it is increasingly recognised that effective delivery of these drugs to the lungs is just as important. The most effective drugs, β 2 -agonists and corticosteroids, are given by inhalation so there has been a search for more efficient inhaler devices that are easier for patients to use. A symposium at the European Respiratory Society Annual Meeting in 2005 discussed some of the important issues in inhaler therapy in adults and children. This article summarises the major points of discussion that arose out of this symposium. New more effective inhaler devices are now becoming available and are likely to have an important impact on asthma management.
No abstract is provided for this article.
Section:ChooseTop of pageAbstract <<TECHNIQUES FOR STUDYING R...β-ADRENOCEPTORSANTICHOLINERGICSCORTICOSTEROIDSMEDIATOR RECEPTORSFUTURE TARGETS IN THE LUN...CONCLUSIONSReferencesCITING ARTICLES
This report describes the 4-year clinical outcomes of the SPIRIT II study, which randomized 300 patients to treatment with the XIENCE V everolimus-eluting stent (EES), or the TAXUS paclitaxel-eluting stent. At 4-year clinical follow-up, which was available in 256 (85.3%) patients, treatment with EES lead to a trend for lower rates of ischemia-driven major adverse cardiovascular events, a composite of cardiac death, myocardial infarction, and ischemia-driven target lesion revascularization (EES 7.7% vs. paclitaxel-eluting stent 16.4%, P = 0.056). Treatment with EES also resulted in a trend toward lower rates of cardiac death and numerically lower rates of myocardial infarction, ischemia-driven target lesion revascularization, and stent thrombosis. Overall, this study reports numerically fewer clinical events in patients treated with EES at 4-year follow-up, which is consistent with results from earlier follow-up.