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201.
An extended logistic model with a varying asymptotic upper bound for long-range peak demand forecasting is described. The model has been applied to a typical fast growing system, the Saudi Consolidated Electric Company. The forecasts are compared with actual demands and with those obtained from classical forecasting methods. The model gave relatively accurate peak demand forecasts compared with other classical methods. The model with a single load observation is capable of producing several peak demand forecasts corresponding to different levels of maximum temperature and various levels of social activity. The forecasts produced by the model were also stable irrespective of the length of the ex-post simulation period  相似文献   
202.
The criterion for crack growth instability in an elastic-softening material that is subjected to displacement control loading conditions is examined. A theoretical analysis of the model of a solid containing two symmetrically situated deep cracks and with tensile loading of the remaining ligament, defines the criterion for crack growth instability. The criterion is expressed in terms of the material's softening characteristics and the solid's geometrical parameters. The analysis covers the complete spectrum of material behaviour from the case where the softening zone is very small to the case where instability does not occur until the softening zone traverses the ligament between the crack tips.  相似文献   
203.
A perinatal death presenting as a possible homicide is reported. An infant was born with a cleft palate, but without other apparent abnormality, to a mother who experienced postpartum depression. The infant apparently died during feeding. A death certificate, giving cot death and congenital malformations as the causes of death, was rejected by the registering authority. The possibility of homicide was considered. Exhumation and autopsy showed multiple abnormalities, including congenital heart disease and the karyotype of DiGeorge's anomaly. The case highlights the value of the autopsy in such cases, and emphasizes the role of cytogenetics, even after considerable postmortem delay.  相似文献   
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After reviewing the records of 111 patients with Fuchs' heterochromic iridocyclitis, we studied the therapy and prognosis of secondary glaucoma in 30 of these 111 patients (27%) who had glaucoma or could be considered glaucoma suspects. Maximal medical therapy was unsuccessful in 22 of the 30 patients (73%). Surgical intervention (mostly trabeculectomies, half with 5-fluorouracil) successfully controlled intraocular pressure (< or = 21 mm Hg with or without medication) in 13 of the 18 operated-on patients (72%) after a mean follow-up of 26 months. All successfully operated-on patients retained a visual acuity of 20/80 or better. We had favorable results, possibly because of modern surgical techniques (use of 5-fluorouracil, sodium hyaluronate) or earlier surgical intervention, or both.  相似文献   
206.
Ten patients with biopsy verified chronic hepatitis C virus (HCV) infection were treated with oral ribavirin at a dose of 1,000-1,200 mg per day in two divided doses for 12 weeks. Serum alanine aminotransferase (ALT) levels and hepatitis C viral ribonucleic acid (RNA) levels in serum were followed prior to, during, and 12 weeks posttreatment. ALT levels decreased significantly in all patients during therapy from a mean level of 3.21 mukat/l (range 1.22 to 7.79) before, to 1.25 mukat/l (range 0.78 to 2.04) at the end of treatment (P < 0.005). Hereafter, relapse to pretreatment levels was seen within 12 weeks after treatment stop. The hepatitis C viral RNA levels decreased from a mean 10 log titer of 4.1 (range 1-6) before treatment to 3.4 (range 1-5) at treatment stop. Five patients did not change their HCV RNA titers during treatment. Twelve weeks posttreatment only 3 patients had lower titers than prior to treatment. We conclude that oral ribavirin seems to reduce the viral load, at least temporarily, in some patients with chronic viremic HCV infection. Further studies are needed to evaluate fully the effect of oral ribavirin on chronic HCV infection.  相似文献   
207.
A central assumption in the goal theory literature is that the degree of commitment to the assigned goal moderates the effectiveness of the goal-setting procedure. However, attempts to empirically verify commitment's moderating role have generally met with failure, calling into question either widely used measures of goal commitment, the moderating assumption itself, or both. Three studies are described that address this issue. Results indicate that the moderation assumption is valid but is only relevant to 1 of 3 closely related motivational concepts that are commonly discussed under the heading of commitment: prechoice attitudes, the subsequent choice of a personal goal, and the maintenance of that choice. It is suggested that a view of commitment that more clearly distinguishes these concepts can provide a better guide for future empirical research than can existing viewpoints. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
208.
PURPOSE: To determine the radiosensitivity of bone marrow stromal cells, the rate of interphase chromosome breakage and rejoining of stromal cells in the murine long term bone marrow culture and of human skin fibroblasts were compared. METHODS AND MATERIALS: The cells were irradiated with doses up to 6 Gy and repair times up to 6 hr were investigated. After induction of premature chromosome condensation by fusing the cells with mitotic HeLa cells, the number of interphase chromosome fragments was counted. RESULTS: The number of radiation induced breaks was found to be not significantly different for both cell types with 6.16 +/- 0.26 breaks per Gray for the fibroblasts and 5.96 +/- 0.20 breaks per Gray for the stromal cells. A significant difference was observed in the repair rate. The fibroblasts rejoined 39.6% of the breaks induced initially during the first hour after irradiation and 5.6 +/- 1.84 breaks remained unrejoined after 6 hr, while the stromal cells were able to rejoin 63.2% in 1 hr and had 2.05 +/- 0.07 breaks unrejoined after 6 hr. CONCLUSION: If the well substantiated assumption is made, that the capacity to repair DNA double strand breaks or interphase chromosome breaks is correlated with the cellular radiosensitivity, this finding indicate, that murine bone marrow stromal cells are more radioresistant than human skin fibroblasts.  相似文献   
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