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Two methods are presented for the computation of the radiation at microwave frequencies in a thin dielectric medium from a source located in a dense dielectric medium. One is based on geometrical optics and the other on physical optics. The geometrical optics approach encounters some difficulties in the evaluation of the radiation in the thin dielectric medium near grazing-incidence condition, due to excitation of a lateral wave, which is not taken in consideration by this approach. The physical optics method, which considers the lateral wave contribution, approaches this problem successfully and gives a better approximation of the radiated field near grazing. Numerical results, which compare the two methods, and experimental data are offered to validate the theoretical approach 相似文献
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97 patients (25 per cent males, ages ranging from 14 to 73 years, median 38 years) with complaints of chronic fatigue (chronic fatigue syndrome, fibromyalgia or/and spasmophilia) have been enrolled in a prospective study to evaluate the Mg status and the dietary intake of Mg. An IV loading test (performed following the Ryzen protocol) showed a Mg deficit in 44 patients. After Mg supplementation in 24 patients, the loading test showed a significant decrease (p = 0.0018) in Mg retention. Mean values of serum Mg, red blood cell Mg and magnesuria showed no significant difference between patients with or without Mg deficiency. No association was found between Mg deficiency, CFS or FM. However serum Mg level was significantly lower in the patients with spasmophilia than in the other patients. 相似文献
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HC Chen MH Cheng AG Schneeberger TJ Cheng FC Wei YB Tang 《Canadian Metallurgical Quarterly》1998,45(3):570-574
Damage of large arteries is a major contributory factor to the high pulse pressure observed in patients with end-stage renal disease. Whether incremental modulus of elasticity (Einc), a classic marker of arterial stiffness, can predict cardiovascular mortality has never been investigated. A cohort of 79 patients with end-stage renal disease undergoing hemodialysis was studied between September 1995 and January 1998. Mean age at entry was 58+/-15 years. The duration of follow-up was 25+/-7 months, during which 10 cardiovascular and 8 noncardiovascular fatal events occurred. At entry, carotid Einc was calculated from measurements of diameter, thickness (echo-tracking technique), and pulse pressure (tonometry). Based on Cox analyses, 2 dominant factors emerged as predictors of all-cause and cardiovascular mortality: increased Einc and decreased diastolic blood pressure. Lipid abnormalities and the presence of previous cardiovascular events interfered to a smaller extent. After adjustment for confounding variables, the odds ratio for Einc >/=1 kPa-3 was 9.2 (95% confidence interval, 2.4 to 35.0) for all-cause mortality. These results provide the first direct evidence that in patients with end-stage renal disease undergoing hemodialysis, arterial alterations, as determined from carotid Einc, are strong independent predictors of all-cause and cardiovascular mortality. 相似文献
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A Ishizuya-Oka S Ueda S Damjanovski Q Li VC Liang YB Shi 《Canadian Metallurgical Quarterly》1997,192(1):149-161
To determine whether the remodeling of the well-organized intestinal epithelium during amphibian metamorphosis is regionally regulated along the anteroposterior axis of the intestine, we raised a polyclonal antibody against the Xenopus laevis intestinal fatty acid-binding protein (IFABP), which is known to be specifically expressed in intestinal absorptive cells, and examined immunohistochemically the differentiation, proliferation, and apoptosis of the epithelial cells throughout X. laevis small intestine. During pre- and prometamorphosis, IFABP-immunoreactive (ir) epithelial cells were localized only in the anterior half of the larval intestine. At the beginning of metamorphic climax, apoptotic cells detected by nick end-labeling (TUNEL) suddenly increased in number in the entire larval epithelium, concurrently with the appearance of adult epithelial primordia. Subsequently, the adult primordia in the anterior part of the intestine developed more rapidly by active cell proliferation than those in the posterior part, and replaced the larval epithelial cells earlier than those in the posterior part. IFABP-ir cells in the adult epithelium were first detectable at the tips of newly formed folds in the proximal part of the intestine. Thereafter, IFABP expression gradually progressed both in the anteroposterior direction and in the crest-trough direction of the folds. These results suggest that developmental processes of the adult epithelium in the X. laevis intestine are regionally regulated along the anteroposterior axis of the intestine, which is maintained throughout metamorphosis, and along the trough-crest axis of the epithelial folds, which is newly established during metamorphosis. Furthermore, the regional differences in IFABP expression along the anteroposterior axis of the intestine were reproduced in organ cultures in vitro. In addition, IFABP expression was first down-regulated and then reactivated in vitro when the anterior part, but not the posterior part, of the larval intestine was treated with thyroid hormone (TH) for extended periods. Therefore, it seems that, in addition to TH, an endogenous factor(s) localized in the intestine itself with an anteroposterior gradient participates in the development of the adult epithelium during amphibian metamorphosis. 相似文献
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