55 research outputs found

    Hydraulics of rigid boundary basins

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    1968 Fall.Includes bibliographical references (pages 237-239).Covers not scanned.Print version deaccessioned 2020.The object of the study was to develop design criteria for three classes (A, B and C) of rigid boundary energy dissipating structures. The Class A basin has a smooth floor and flaring vertical walls; the Class B basin is a rectangular basin with smooth floor and vertical walls; the Class C basin is a rectangular basin with smooth vertical walls and an artificially roughened floor. Design aids developed during this study include: dimensionless coefficients for the energy and momentum equations which correct for nonhydrostatic pressure distribution and nonuniform velocity distribution at the outfall sections of circular and rectangular conduits; dimensionless water surface contours and velocity vectors for freely expanding jets supported on the bottom, downstream of circular and rectangular abrupt expansions; drag coefficients for roughness elements of known size and spacing; and other minor criteria. Numerous existing criteria, including Blaisdell's criterion for wall flare, Ippen's relationships for predicting the angle of oblique standing waves and Albertson, et al.'s relationships for determining the properties of the flow field downstream of culvert outlets operating under high tailwater conditions were verified. Design procedures based on continuity of flow and the balance of impulse and momentum from station to station are presented for the three classes of basins. Alternate refined procedures utilizing backwater computations are outlined for Class A and B basins. Numerous example problems are solved in detail in Chapter VII. It is suggested that the energy basin be constructed within the roadway prism as an integral portion of the culvert barrel. Discussions concerning the necessity of tailwater control and of other important factors which should be considered accompany the design computations

    Flood protection at culvert outlets

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    CER69-70DBS-MAS-FJW4.Includes bibliographical references (pages 59-60).Prepared for Wyoming State Highway Department, Planning and Research Division in cooperation with the U.S. Department of Transportation, Federal Highway Administration, Bureau of Public Roads.In this study several classes of information concerning flood protection at culvert outlets are presented. The information is related to the flow conditions at culvert outfalls and to the hydraulics of rigid basins and outlet basins stabilized with rock riprap. In addition, the characteristics of high tailwater and non-scouring, low tailwater basins are covered. In this report it is intended that a hydraulic engineer can take the information contained in the text, examples, illustrations, and figures and apply it toward the design of an energy dissipator of maximum effectiveness. The data on which the report is based were gathered mostly during an experimental program at Colorado State University. In some cases, adequate data were available from other sources. Where such information was needed, it was incorporated into the report

    Effect of Alirocumab on Lipoprotein(a) Over ≥1.5 Years (from the Phase 3 ODYSSEY Program)

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    Elevated lipoprotein(a) [Lp(a)] is independently associated with increased cardiovascular risk. However, treatment options for elevated Lp(a) are limited. Alirocumab, a monoclonal antibody to proprotein convertase subtilisin/kexin type 9, reduced low-density lipoprotein cholesterol (LDL-C) by up to 62% from baseline in phase 3 studies, with adverse event rates similar between alirocumab and controls. We evaluated the effect of alirocumab on serum Lp(a) using pooled data from the phase 3 ODYSSEY program: 4,915 patients with hypercholesterolemia from 10 phase 3 studies were included. Eight studies evaluated alirocumab 75 mg every 2 weeks (Q2W), with possible increase to 150 mg Q2W at week 12 depending on LDL-C at week 8 (75/150 mg Q2W); the other 2 studies evaluated alirocumab 150-mg Q2W from the outset. Comparators were placebo or ezetimibe. Eight studies were conducted on a background of statins, and 2 studies were carried out with no statins. Alirocumab was associated with significant reductions in Lp(a), regardless of starting dose and use of concomitant statins. At week 24, reductions from baseline were 23% to 27% with alirocumab 75/150-mg Q2W and 29% with alirocumab 150-mg Q2W (all comparisons p <0.0001 vs controls). Reductions were sustained over 78 to 104 weeks. Lp(a) reductions with alirocumab were independent of race, gender, presence of familial hypercholesterolemia, baseline Lp(a), and LDL-C concentrations, or use of statins. In conclusion, in addition to marked reduction in LDL-C, alirocumab leads to a significant and sustained lowering of Lp(a)

    Low-density lipoproteins cause atherosclerotic cardiovascular disease. 1. Evidence from genetic, epidemiologic, and clinical studies. A consensus statement from the European Atherosclerosis Society Consensus Panel

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    Aims To appraise the clinical and genetic evidence that low-density lipoproteins (LDLs) cause atherosclerotic cardiovascular disease (ASCVD). Methods and results We assessed whether the association between LDL and ASCVD fulfils the criteria for causality by evaluating the totality of evidence from genetic studies, prospective epidemiologic cohort studies, Mendelian randomization studies, and randomized trials of LDL-lowering therapies. In clinical studies, plasma LDL burden is usually estimated by determination of plasma LDL cholesterol level (LDL-C). Rare genetic mutations that cause reduced LDL receptor function lead to markedly higher LDL-C and a dose-dependent increase in the risk of ASCVD, whereas rare variants leading to lower LDL-C are associated with a correspondingly lower risk of ASCVD. Separate meta-analyses of over 200 prospective cohort studies, Mendelian randomization studies, and randomized trials including more than 2 million participants with over 20 million person-years of follow-up and over 150 000 cardiovascular events demonstrate a remarkably consistent dose-dependent log-linear association between the absolute magnitude of exposure of the vasculature to LDL-C and the risk of ASCVD; and this effect appears to increase with increasing duration of exposure to LDL-C. Both the naturally randomized genetic studies and the randomized intervention trials consistently demonstrate that any mechanism of lowering plasma LDL particle concentration should reduce the risk of ASCVD events proportional to the absolute reduction in LDL-C and the cumulative duration of exposure to lower LDL-C, provided that the achieved reduction in LDL-C is concordant with the reduction in LDL particle number and that there are no competing deleterious off-target effects. Conclusion Consistent evidence from numerous and multiple different types of clinical and genetic studies unequivocally establishes that LDL causes ASCVD.Peer reviewe
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