There is conflicting evidence as to which autonomic receptors mast cells possess and whether the receptors are capable of modulating mediator release. We have studied dog mastocytoma cells because ...
The structural behaviour of sheathed cold-formed steel lipped channel section columns (studs) subjected to combined compression and major axis bending is investigated herein by means of numerical modelling. Finite element (FE) models of single studs, set in tracks and connected to oriented strand board (OSB) and gypsum plasterboard sheathing under varying combinations of axial compression and horizontal loading were developed in ABAQUS and validated against experimental results reported in the literature. The developed numerical models incorporated cross-sectional and global geometric imperfections, while geometrical and material nonlinearities for both the steel and the sheathing were considered in the analyses. Particular emphasis was given to replicating the “as-built” boundary conditions at the ends of the columns, controlled by the screws connecting the column to the track and by the column–track contact interaction. The interaction between the sheathing and the column, as well as the behaviour of the fasteners connecting the two components, were also explicitly modelled. Both the shear and pull-through characteristics of the fasteners were considered and simulated based on experimental findings. Following successful validation of the finite element models, parametric studies were conducted. The results showed that substantial structural performance benefits can be achieved by the addition of sheathing to cold-formed steel members and that the spacing of the connectors has a strong influence on the member response. For a typical system, decreasing the connector spacing from 300 mm to 75 mm was found to increase stud capacity and stiffness by up to 12% and 10% respectively when in pure compression and up to 26% and 22% respectively when in pure bending; under combined loading, capacity increases of up to 29% were found.
Structural sections manufactured from stainless steel possess several features that mean that their response to loading differs from that of equivalent members made from carbon steel. To date these features have not really been recognised in design codes, which have largely adapted rules devised for carbon steel in a rather simplistic fashion. Recently, a new approach for dealing with local buckling and the associated loss of effectiveness that does not utilise the concepts of either cross-sectional classification or effective cross-sectional properties has been developed; it is therefore particularly well suited to dealing with stainless steel. Originally the concept was restricted in application to closed sections. It is extended herein to cover both open and closed cross-sections. It is then incorporated in the procedures for designing columns and beam-columns based on the Eurocode approaches and it is shown that by making further modifications the accuracy of these methods can be significantly improved. The resulting design procedures are no lengthier than those currently given in the stainless steel part of EC3.
Stent implantation has become the new standard angioplasty procedure. In-stent re-stenosis remains the major limitation of coronary stenting. Re-stenosis is related to patient-, lesion- and procedure-specific factors.
When administered intravenously at the time of percutaneous coronary revascularization, glycoprotein IIb/IIIa receptor antagonists decrease the incidence of death and nonfatal myocardial infarction and the need for urgent revascularization. We hypothesized that long-term administration of oral glycoprotein IIb/IIIa antagonists, which block the aggregation of platelets, might stabilize intravascular plaque and prevent additional ischemic cardiac events.
Although previous intravascular ultrasound (IVUS) radiofrequency-based analysis data showed acceptable reproducibility for plaque composition, measurements are not easily obtained, particularly that of lumen contour, because of the limited IVUS resolution. The purpose of this study was to compare a new measurement method (Shin's method) and the conventional measurement method for necrotic core and calcium content in atherosclerotic lesions using Virtual Histology-intravascular ultrasound (VH-IVUS). Fifty-seven patients with unstable angina who underwent elective percutaneous coronary intervention were included. Shin's method focuses on catheter contour, instead of lumen contour, and vessel contour. Patients ages ranged from 46 to 88 years, and 34 were men. A total of 1,401 frames from 59 culprit lesions were assessed. There were no significant differences in the mean area and volume of necrotic core and dense calcium between the two methods. Correlation coefficients (R) were >or=0.99 for all above mentioned parameters (P < 0.001). Between methods, the absolute differences in mean area and volume of necrotic core were 0.02 +/- 0.02 mm(2) and 0.34 +/- 0.29 mm(3), respectively, while for mean area and volume of dense calcium, the absolute differences were 0.04 +/- 0.07 mm(2) and 0.36 +/- 0.52 mm(3), respectively. The reproducibility of Shin's method was excellent. For area of the necrotic core and dense calcium, the means of the differences between the two measurements were nearly zero, and the reproducibility coefficients were within 1% of the means of the two measurements. Mean analysis time for both measurements was 26.8 +/- 6.7 min/segment in the conventional method and 3.3 +/- 0.6 min/segment in Shin's method. Shin's method for measurement of necrotic core and dense calcium using VH-IVUS demonstrated a good correlation with the conventional method and excellent reproducibility. Also, Shin's method required a significantly shorter analysis time than the conventional method. Therefore, Shin's method could replace the conventional method for necrotic core and calcium measurement in atherosclerotic lesions, and it might be useful in the catheterization laboratory for online clinical decision.
Cereal grains contain relatively small quantities of lipids, usually from 2 to 6%, but these lipids are, nevertheless, important constituents of the grain and grain products. They consist mainly of oily triglycerides together with phospholipids and glycolipids (fatty materials containing phosphorus and sugars respectively) and influence the performance of wheat flour in breadmaking, the flavour of oatmeal, the colour of pasta and the storage stability of cereals. The fatty acids in the cereal lipids are mostly polyunsaturated, which is good news in terms of nutrition but a problem during storage; oxidation of the polyunsaturated acids can lead to off‐flavours.
. The attempt to salvage myocardium threatened by ischemia during temporary or permanent occlusion of one or more of the nutrient arteries, is based on the observation that the major determinant of survival is the extent to which myocardium has been lost through infarction. Modern clinical cardiology has therefore looked at various approaches which might limit unnecessary loss of potentially viable myocardium. These are attempts to reduce the oxygen consumption through pharmacological means, attempts at restoring the blood supply and oxygen delivery at an early stage by manipulations on the coronary arteries and interventions aimed at »protecting» cardiac cells threatened by ischemia or reperfusion. Endpoints considered to be proof of improved left ventricular function will be wall motion and ejection fraction measurements as well as reduction in death rate and other serious cardiovascular complications.