نتایج جستجو برای: سیستم مهاربندی پیشنهادی mbf
تعداد نتایج: 91354 فیلتر نتایج به سال:
در ساختمانهای بتنی برای مقابله با نیروهای جانبی، معمولاً سیستمهایی مانند قاب خمشی، دیوار برشی و یا ترکیبی از این دو استفاده میشود. استفاده از مهاربندی کابلی به صورت ضربدری، روش جدیدی برای مقاومسازی آنها میباشد. این سیستم به دلیل وزن کم کابل، مقاومت کششی بسیار بالای کابل، سهولت اجرا و عدم نیاز به تعمیر و نگهداری نسبت به سایر سیستمهای مقاومسازی بسیار اقتصادی است. در این سیستم جهت افز...
در سالهای اخیر استفاده از مهاربند کمانشتاب به عنوان سیستم مقاوم در برابر زلزله در کشورهای پیشرو در علم سازه و زلزله توسعه یافته است. به دلیل شکلپذیری این سیستم و رفتار مناسب آن، مهاربند کمانشتاب جایگزین مناسبی برای سیستمهای متداول مهاربندی به شمار میرود. سیستمهای مهاربندی کمانشتاب معمولا در الگوی همگرا مورد توجه بوده است و تاکنون در الگوی واگرا مورد استفاده قرار نگرفته است. استفاده از الگوی...
Background Quantitative myocardial perfusion imaging requires correct measurement of arterial Gd concentration as the input function (AIF). An underestimation of AIF Gd concentration will lead to overestimation of myocardial blood flow (MBF). One source of this underestimation is the T2* effect due to high Gd concentration in the AIF measurement. Despite the short echo time (0.65 ms) used in th...
BACKGROUND Although impairment in perfusion reserve is well recognized in hibernating myocardium, there is substantial controversy as to whether resting myocardial blood flow (MBF) is reduced in such circumstances. Quantitative first-pass cardiovascular magnetic resonance (CMR) perfusion imaging allows absolute quantification of MBF. We hypothesized that MBF assessed at rest by quantitative CMR...
Chronic Myocardial Hiberation The study of Vanoverschelde et al' demonstrated significant abnormalities on morphological analysis of myocardial biopsies from patients with chronic myocardial hibernation. These morphological changes are very similar to those described previously2 and do not occur in stunning; thus, the investigators correctly state that their patients with left ventricular dysfu...
Background Following acute myocardial infarction (AMI), microvascular integrity and function may be compromised as a result of microvascular obstruction (MVO) and vasodilator dysfunction [1,2]. It has been observed that both infarct and remote myocardial territories may exhibit impaired myocardial blood flow (MBF) patterns associated with abnormal vasodilator response [3]. Arterial spin labeled...
This study was undertaken to determine the relationships between myocardial mitochondrial function, regional myocardial blood flow (MBF), and tissue ATP content in acute ischemia. Fifty-one anesthetized dogs were used in the tests. MBF was measured by the H2 gas clearance method in order to define the ischemic area, during periods of coronary occlusion of 10, 20, 60, and 90 min. The correlation...
AIM To compare the interocular and intraocular differences of capillary perfusion, and the intraocular regional differences of retinal blood flow in the macular area of healthy volunteers. METHODS Tissue blood flow in the macula was examined in both eyes of 20 healthy volunteers with the Heidelberg retinal flowmeter. Blood flow measurements were made in a 10 degrees x 2.5 degrees area superio...
The controversy regarding the mechanism(s) of left ventricular (LV) dysfunction in chronic coronary artery disease is, in part, related to the lack of an appropriate animal model for this condition. We have developed such a model by placing Ameroid constrictors on proximal portions of coronary arteries in dogs who were euthanized (mean of 6 wk) after the development of severe global LV dysfunct...
Background Myocardial blood flow (MBF) can be quantified from arterial input function (AIF) and myocardial output function in perfusion MRI by using tracer kinetic modeling. Fermi function constrained deconvolution has been widely used to determine MBF and myocardial perfusion reserve (MPR). However, stress MBF and MPR in healthy subjects quantified by the Fermi deconvolution approach were repo...
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