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81.
The influence of antihypertensive treatment on the long-term evolution of arterial pressure and renal function was studied in a prospective controlled trial conducted in renal transplant recipients treated by cyclosporine. Within six months after transplantation, patients were randomly allocated to treatment by the angiotensin-converting enzyme inhibitor, lisinopril (ACEI, alone or associated with frusemide; N = 14), or the calcium antagonist, nifedipine (CA, alone or associated with atenolol; N = 11). Glomerular filtration rate (TcDTPA clearance) and effective renal plasma flow (hippuran clearance) as well as 24-hour urinary excretion of electrolytes and albumin were estimated at about 1 and 2.5 years of follow-up. Before initiation of antihypertensive therapy, the two groups were similar with regards to mean arterial pressure (119 +/- 2 vs. 120 +/- 4 mm Hg), effective renal plasma flow (285 +/- 26 vs. 248 +/- 33 ml/min/1.73 m2) and glomerular filtration rate (59 +/- 4 vs. 61 +/- 8 ml/min/1.73 m2 in the ACEI and CA groups, respectively). Both ACEI and CA treatments were associated with no change in renal function, a similar change in mean arterial pressure (ACEI -18 +/- 3; CA -13 +/- 5 mm Hg) and identical trough blood levels of cyclosporine. Urinary albumin excretion did not change significantly in any groups. Of interest, only in the ACEI group did filtration fraction significantly decrease (from 0.22 +/- 0.01% to 0.19 +/- 0.01% at final studies). These results indicate that in cyclosporine-treated transplant recipients, a satisfactory control of hypertension is obtained by chronic ACEI, which is as effective on arterial pressure as a combination of CA and atenolol.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
82.
The quasi-likelihood function is used to derive Bayesian and non-Bayesian estimates for the unknown parameters of the Pareto distribution. In the Bayesian technique the likelihood function is replaced with the quasi-likelihood function when the mean-variance relationship is defined. The efficiency of the quasi-likelihood estimation relative to the maximum likelihood is calculated. Numerical illustrations for the Bayesian and quasi-Bayesian procedures are given. 相似文献
83.
A.-H. I. Mourad S. K. Maiti 《Fatigue & Fracture of Engineering Materials & Structures》1996,19(1):75-84
Abstract Mode II stable crack extension has been examined for an aircraft grade aluminium alloy D16AT. Both theoretical and experimental results are presented. The experimental observations include load displacement diagrams, plastic wake, crack front tunnelling and scanning electron micrographs of the fracture surfaces. The crack shows a tendency for in-plane extension, and the fracture surface is very flat, smooth and free of any dimples. The crack front advances with neghgible tunnelling at all stages of extension. The span of mode II stable crack growth (SCG) is longer than in the case of mode I SCG reported earlier for the same material and there is also more extensive plastic deformation. In the presence of a slight mode I load, the crack grows out-of-plane and the fractured surface facets resemble that of a mode I or mixed-mode dimpled fracture. The theoretical study is based on a finite element analysis using small deformation theory and incremental plasticity. Some of the experimental results have been theoretically predicted using the COA criterion as the governing criterion. The theoretical results include load-displacement diagrams, crack edge displacement curves, plastic zones and the J resistance curves. There is good agreement between the load-displacement diagrams. The initiation and maximum loads differ by less than 15%. The J resistance curve has a constant slope over the whole span of stable crack growth. 相似文献
84.
85.
This paper introduces a solution of the dynamic economic dispatch (DED) problem using a hybrid approach of Hopfield neural network (HNN) and quadratic programming (QP). The hybrid algorithm is based on using enhanced HNN; to solve the static part of the problem; the QP algorithm for solving the dynamic part of the DED. This technique guarantees the global optimality of the solution due to its look-ahead capability. The new algorithm is applied and tested to an example from the literature and the solution is then compared with that obtained by some other techniques to prove the superiority and effectiveness of the proposed algorithm. 相似文献
86.
Multimedia Tools and Applications - In this paper, we present a novel classification approach based on Extreme Learning Machine (ELM) and Wavelet Neural Networks. We introduce two novel... 相似文献
87.
88.
Hamza Saidi Walid Aloui Abdelaziz Bouazizi 《Journal of Materials Science: Materials in Electronics》2018,29(21):18051-18058
The electrical proprieties of poly (3-hexylthiophene): Silicon nanowires (P3HT: SiNWs) nanocomposite was investigated by impedance spectroscopy technique. The effect of bias voltage under and without illumination was discussed. Indeed, the imaginary part of the impedance shows a high relaxation frequency related to Maxwell–Wagner–Sillars (MWS) polarization. The relaxation time was found in the range of ms and it was shifted towards high frequency with increasing the bias voltage especially at 0.6 V At bias voltage equal to Vth and under illumination, the conductivity increases because the trapped charges acquire the necessary energy to escape from the interface and the hopping time found was reduced. This indicates a change of the conduction mechanism. The Cole–Cole diagram was excellently fitted through an equivalent circuit including a chemical capacitance Cµ, a contact electrical resistance Rs and recombination resistance Rp. 相似文献
89.
90.
Khalil Mokhtari Abdelhafid Elhadri Mourad Abdelaziz 《International Journal of Adaptive Control and Signal Processing》2019,33(9):1359-1373
For a class of nonlinear systems with the representation {A(x), B(x), C} and where the system parameters and dynamics are unknown, a simple adaptive synergetic controller ensuring the asymptotic convergence of the system to a desired manifold is proposed based on the technique of simple adaptive control (SAC). It is well known that the design of the synergetic control (SC) law requires a thorough knowledge of the system parameters and dynamics. Such problem obstructs the synthesis of the SC law and the designer is prompted to pass through the estimation methods, which, in turn, poses a problem of increasing the computation time of the control algorithm. To cope with this problem, a solution is proposed by modifying the original SC law to develop an SAC‐like adaptive SC law without the need of prior knowledge of the system. The stability of the proposed adaptive controller is formally proven via the Lyapunov approach. Experimental application to a quadrotor system is given to validate the theoretical results. 相似文献