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41.
To manage cost risk, prudent procurement of electric power requires that some portion of a buyer's energy demand be met through long-term contracting. Under cost-of-service regulation or performance-based regulation, a local distribution company (LDC) should be allowed to fully recover all prudently incurred power procurement costs. However, the regulatory test of prudence is an ex post review with the threat of disallowance. This paper presents an economic analysis of procurement prudence involving a small LDC, Bear Valley Electric Service (BVES), which serves a resort area in Southern California. The key findings are: (a) high and volatile prices and rolling blackouts characterized the market environment faced by the owner of BVES, Southern California Water Company (SCWC), at its signing of a 5-year fixed price contract; (b) SCWC was a price-taker with no incentive to act imprudently; (c) the contract was obtained via a competitive bidding process; (d) the contract price was comparable to the benchmark price of contemporaneous contracts; (e) the fixed price contract was economic when compared to available alternatives; and (f) despite (a)–(e), a negotiated settlement with the state regulator and a large user resulted in substantial disallowance. The policy implication is that a regulator should approve a prudent procurement plan proposed by an LDC to remove the unreasonable risk of an ex post review. If the LDC strictly adheres to the plan, the resulting electricity purchases are per se prudent and should entitle the LDC to full cost recovery. 相似文献
42.
Lloyd M. Robeson 《乙烯基与添加剂工艺杂志》1990,12(2):89-94
Polymer blends have received particular interest in the past several decades in both industrial and academic research. An initial survey of miscible polymer pairs (1) (1968) revealed 12 combinations. A later survey (2) (1979) noted approximately 180 miscible pairs. Today possibly over 500 miscible combinations have been noted in the open and patent literature (3). However, the vast majority of possible polymer blend combinations are not miscible (thus phase separated). A significant number of diverse polymer structures have been shown to exhibit miscibility with PVC. Several of these blends have been studied in detail and have shown specific interactions primarily involving the α-hydrogen and PVC (considered the proton donor in proton donor-proton acceptor hydrogen bonding type interactions). The blend of poly(?-caprolactone) with PVC illustrates this interaction and has been reported in many published papers. While polymer miscibility in PVC blends offers significant academic interest, industrial utility is also of considerable importance. The addition of low Tg, miscible polymers to PVC offers permanent plasticization. The addition of high Tg, miscible polymers to PVC yields the desired heat distortion temperature enhancement of rigid PVC. A specific example of permanent plasticization involves nitrile rubber blends which have been commercial since the early 1940's. This presentation will review the growing number of polymers noted to be miscible with PVC. The importance of specific interactions will be discussed. 相似文献
43.
MD Cave 《Canadian Metallurgical Quarterly》1976,71(1):49-58
1. Three resorcinol derivatives with N-isopropyl (orciprenaline), N-t-butyl (terbutaline) and N-p-hydroxypheny-t-butyl (Me506) amine substituents have been compared with (--)-isoprenaline for their ability to produce beta-receptor mediated reductions in serotonin-induced increases in pulmonary resistance, decreases in soleus muscle contractility and increases in heart rate in anaesthetized cats. 2. For all parameters studied the four compounds produced similar maximal responses and dose-response curves were close to parallel. From the graphs doses of the compounds producing 50% of the maximal response (ED50) were interpolated, and from these dose-ratios with respect to (--)-isoprenaline [drug ED50:(--)-isoprenaline ED50] were calculated on a molar basis. 3. Increasing the size of the amine substituent from N-isopropyl to N-t-butyl led to an increase in beta-receptor stimulant activity in bronchial and skeletal muscle, but not in the heart. The change from N-t-butyl to N-p-hydroxyphenyl-t-butyl did not further affect stimulant activity in any of the parameters studied. 4. Calculation of selectivity ratios [molar dose-ratio (heart): molar dose-ratio (pulmonary resistance)] showed that orciprenaline was non-selective, and that terbutaline and Me506 showed a similar degree of selectivity for beta2- as opposed to beta1-receptor mediated actions. 相似文献
44.
Time-response curves were established for the effect of 3 doses of pimozide, a potent and specific dopamine receptor blocker, on deprivation-induced drinking in rats. Injections occurred once every 3 days at intervals of 2, 4, 8, and 16 hr prior to the daily 15 min drinking period. Pimozide produced a significant attenuation in the amount of water normally consumed (on nondrug days) whose degree varied with the proximity of the injection to the drinking period. Only the 2 higher doses (0.5 and 1.0 mg/kg) produced a significant dose dependent effect which was strongest at the 2 hr interval and which gradually weakened by the 8th post injection hr. The relevance of these findings for a direct versus an indirect action of the drug on water intake is discussed. 相似文献
45.
The histochemical localization of carbohydrates and lipids and some oxidative, hydrolytic and steroid-linked enzymes has been studied in the testis of the camel with particular reference to the effect of the season on the distribution of these substances. PAS-positive, but diastase-resistant, material was seen mainly in the wall of blood vessels and in the boundary tissues of the seminiferous tubules, tubuli recti and rete testis. Clear cyclical changes were seen for glycogen in the lining epithelium of the seminiferous tubules. Glycogen was most abundant in early stages and very scanty or absent in the late stages of the cycle of the seminiferous epithelium. Numerous small lipid droplets were seen in the interstitial cells and towards the lumen of the seminiferous tubules that contain elongate spermatids or spermatozoa. Large lipid droplets were also demonstrable in the basal layer of the seminiferous epithelium and in the cytoplasmic debri. Alkaline phosphatase was demonstrated in the boundary tissues of the seminiferous tubules, tubuli recti and reti testis and in the cells bordering the lumen of the seminiferous tubules. Succinate and lactic dehydrogenases showed similar patterns of distribution in the interstitial elements and intratubularly. delta5-3beta hydroxysteroid dehydrogenase was exclusively demonstrated in the interstitial cells. 17beta-hydroxysteroid dehydrogenase could not be demonstrated. The season seems to have no effect on the distribution of all these substances. The possible significance of all these findings is discussed. 相似文献
46.
Two percept-genetic methods, the Meta-Contrast Technique (MCT) and the Serial Afterimage Test (AI), were used to study adaptive aspects of perception in a group of 37 subjects suffering from manifest anxiety. The perceptual processes laid bare by these methods reflected not only anxiety but also defensive formations. MCT and AI correlated with each other in these respects and, when combined, correlated with rated symptoms. In accordance with the theory behind percept-genetic methods, anxiety signs appearing late in the test serials were more likely to correspond to manifest symptoms than signs which appeared early. The AI test scores seemed to reflect a difference between anxiety experienced as an inherent quality of life and anxiety as a foreign force struggling for dominance. 相似文献
47.
Sixty Sprague-Dawley rats were fed diets containing 0, 10, 100, 1,000, and 10,000 ppm of methoxychlor for 16 weeks under ad libitum- and restricted-feeding regimens. Methoxychlor at 10,000 ppm was lethal to some rats, reduced food consumption and growth, and increased liver weight relative to body weight. Methoxychlor at 1,000 ppm reduced food consumption and growth of rats fed ad libitum but did not reduce growth of restricted-fed rats. Reduced hepatic storage of vitamin A was detectable when methoxychlor was fed at levels of 100 ppm or higher. 相似文献
48.
Results of studies have suggested that endotoxin and lowered coronary arterial perfusion pressures are detrimental to cardiac performance and lead to failure. Prevention of cardiac failure in the isolated canine heart preparation confronted with endotoxin and decreased coronary perfusion pressure was possible by perfusing these hearts with sodium nitroprusside. Prevention of failure was manifested by a lowered left ventricular endiastolic pressure and was associated with increased coronary flow and decreased coronary resistance with increased oxygen delivery and decreased oxygen extraction. Possible explanations for improved performance by dilator perfusion include increased delivery of oxygen and nutrients to myocardial tissue as well as a reduction of ventricular wall tension by dilating the coronary vascular skeleton. Prevention of extravasation of interstitial fluid into myocardial tissue by reducing overperfusion of potentially damaged coronary vessels could serve to maintain myocardial integrity and ventricular compliance. The potential use of such therapy warrants further study, with emphasis on evaluating the hemodynamics of the intact animal. 相似文献
49.
50.
MD Norenberg 《Canadian Metallurgical Quarterly》1976,33(4):265-269
Results of a histochemical study of glutamic dehydrogenase in experimental portal-systemic encephalopathy with hyperammonemia indicate that the enzyme's activity in brain was increased in all stages of the encephalopathy, and this increase appeared to be localized exclusively in astrocytes. The results are consistent with the view that the astrocyte has a critical role in ammonia metabolism in brain, probably in ammonia detoxification. The findings, moreover, indicate that one pool of glutamate, possibly the small pool, is located in the astrocyte. 相似文献