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11.
Presented are the fade duration dynamics as observed in four close stations. Fade duration statistics derived from the collected received signal during a critical period in the region are presented and analysed. The obtained results are compared with the model release by the ITU-R P.1623 recommendation. Some modifications are then proposed. 相似文献
12.
Explores several questions relating to historical inquiry in the field of social psychology. During its Golden Age, 1945–1970, social psychology was busy defining different fields and paradigms, building theories, and verifying hypotheses; there was little time and need for reflection. The 1970s saw an era of doubts, critique and crisis, during which the constituted knowledge bases were undermined on a number of fronts: methodological, ethical, and theoretical. Examples of how critical history may serve a heuristic function for social psychology are given. The question of how to conduct historical inquiry is addressed, even for as problematic an object as social psychology's development in France. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
13.
In the present study, we assessed oxidative stress in patients with dilated cardiomyopathy of ischemic or idiopathic etiology. For this reason we measured whole blood reduced glutathione, erythrocyte superoxide dismutase, susceptibility of erythrocyte membranes and erythrocytes to peroxidation, and SH content of erythrocyte membranes in 12 patients (8 men and 4 women, ages 31 to 66 years) with idiopathic dilated cardiomyopathy, in 11 patients (8 men and 3 women, ages 32 to 65 years) with ischemic dilated cardiomyopathy, and in 21 healthy volunteers (12 men and 9 women, ages 25 to 67 years). There was no statistically significant difference between the two patient groups for the indicators studied (P >0.05). Blood glutathione, erythrocyte superoxide dismutase, and membrane SH content of both groups of patients was decreased compared with controls (P <0.05), whereas erythrocyte and membrane susceptibility to peroxidation were increased (P <0.05). We conclude that patients with idiopathic or ischemic dilated cardiomyopathy exhibit abnormalities of a range of markers of increased oxidative stress. These abnormalities may contribute to contractile dysfunction, increased incidence of fatal arrhythmias, and sudden death. 相似文献
14.
The United States has historically excelled in the design of products, processes and new technologies. Capitalizing on this historical strength to teach applied mathematics and science has many positive implications on education. First, engineering design can be used as a vehicle for addressing deficiencies in mathematics and science education. Second, as achievement in mathematics and science is enhanced, a greater number of students at an earlier age will be exposed to technical career opportunities. Third, enhancing elementary and secondary curricula with engineering design can attract underrepresented populations, such as minorities and females, to engineering as a profession. This paper describes a new and innovative engineering design curriculum, under development in the Austin Independent School District (AISD) in Austin, TX. The philosophic goals upon which the curriculum is based include: integrating the design problem-solving process into elementary schools, demonstrating the relationship of technical concepts to daily life, availing teachers with instructional strategies for teaching applied (as opposed to purely theoretical) science and mathematics, and teaching teamwork skills that are so greatly needed in industry and everyday life. Based on these goals, kindergarten, first grade, and second grade engineering design lessons have been piloted in AISD, in conjunction with a University of Texas program for teacher enhancement and preparation. 相似文献
15.
Sandra L. McLellan Erika J. HollisMorgan M. Depas Meredith Van DykeJosh Harris Caitlin O. Scopel 《Journal of Great Lakes research》2007,33(3):566-580
Escherichia coli distribution and persistence in nearshore Lake Michigan were assessed following heavy rains and sanitary sewer overflow (SSO) and combined sewer overflow (CSO) events over a 5-year period, including an 18-day period following 25.4 cm of rainfall in which intensive studies were conducted following multiple CSO and SSO events. E. coli levels in the Milwaukee estuary and harbor following SSO and CSO events ranged from 104 to nearly 105 CFU/100 mL, which were significantly higher (p ≤ 0.05) than levels following rainfall alone. Sites outside of the breakwall but within the contamination plume (e.g., within 2 km of the harbor) were an order of magnitude lower. Locations 2–5 km from the harbor ranged from below detection limits, of < 1 to 5 CFU/100 mL. E. coli levels corrected for dilution based on specific conductivity measurements were lower than what would be expected for loss due to dilution alone, suggesting a combination of die-off and dilution, were responsible for the rapid disappearance of these organisms outside of the harbor. E. coli and fecal coliforms measured concurrently demonstrated that fecal coliforms could be recovered longer than E. coli in the open waters of the lake. E. coli isolated directly from sewage treatment plant influent were found to have a marked increase in antibiotic resistance traits for ten antibiotics commonly used in the human population compared with isolates from two animal sources of fecal pollution. However, E. coli obtained from sewage impacted water (n = 2,513) and from stormwater impacted water (n = 1,465) collected the previous year when there were no sewage overflows, were found to have no significant difference (p < 0.05) in the frequency of resistance when comparing the two conditions. E. coli survival characteristics and population dynamics are most likely influenced by multiple factors in complex systems such as the watershed/estuarine/lake environments of the Great Lakes. 相似文献
16.
Plasma and blood lead concentrations, lead absorption, and lead excretion in nonhuman primates 总被引:2,自引:0,他引:2
EJ O''Flaherty MJ Inskip AP Yagminas CA Franklin 《Canadian Metallurgical Quarterly》1996,138(1):121-130
The effects of pH, temperature, block of energy production, calcium/calmodulin, protein phosphorylation, and cytoskeleton-disrupting agents (cytochalasin D, nocodazole) on the integrity of the membrane skeleton were studied in polarized MDCK cells. The intracellular distributions of alpha-fodrin, actin, and ankyrin were monitored by immunofluorescence microscopy. The membrane skeleton, once assembled, seemed to be quite stable; the only factors releasing alpha-fodrin from the lateral walls were the acidification of the cytoplasm and the depletion of extracellular calcium ions. Upon cellular acidification, some actin was also released from its normal location along the lateral walls and was seen in colocalization with alpha-fodrin in the cytoplasm, whereas ankyrin remained associated with the lateral walls. No accumulation of plasma membrane lipids was observed in the cytoplasm of acidified cells, as visualized by TMA-DPH. These results suggest that the linkages between the fodrin-actin complex and its membrane association sites are broken upon acidification. The pH-induced change in alpha-fodrin localization was reversible upon restoring the normal pH. Reassembly of the membrane skeleton, however, required temperatures above +20 degrees C, normal energy production, proper cell-cell contacts, and polymerized actin. Release of alpha-fodrin from the lateral walls to the cytoplasm was also observed upon depletion of extracellular calcium ions. This change was accompanied by the disruption of cell-cell contacts, supporting the role of proper cell-cell contacts in the maintenance of the membrane skeleton polarity. These results suggest that local alterations of the cytoplasmic pH and calcium ion concentration may be important in regulating the integrity of the membrane skeleton. 相似文献
17.
The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage and administration of torsemide are reviewed. Torsemide belongs to the pyridine-sulfonylurea class of loop diuretics. Its primary site of activity is the thick ascending limb of the loop of Henle, where it blocks active reabsorption of sodium and chloride, resulting in diuresis, natriuresis, and other effects. Torsemide has high bioavailability, a relatively long half-life, and a prolonged duration of activity. It is highly protein bound. Clinical trials indicate that torsemide is effective in the treatment of hypertension and of edema and other symptoms in patients with chronic renal failure (CRF), hepatic dysfunction, or congestive heart failure (CHF). Torsemide has infrequent, mild, and transient adverse effects; among the most common are orthostatic hypotension, fatigue, dizziness, and nervousness. The recommended initial oral dosages of torsemide are 10-20 mg/day for CHF, 20 mg/day for CRF, 5 mg/day for hypertension, and 5-10 mg/day (in combination with a potassium-sparing diuretic or aldosterone antagonist) for hepatic cirrhosis. In most patients, the pharmacokinetic advantages of torsemide over other loop diuretics are unlikely to translate into a substantial edge in clinical outcomes, and in practice there may be no cost advantages. Although torsemide does not offer major advantages over other loop diuretics, it may be of benefit in patients who do not respond to or cannot tolerate other agents. 相似文献
18.
19.
Hemispheric contributions to the integration of visual and auditory information in speech perception
Differential hemispheric contributions to the perceptual phenomenon known as the McGurk effect were examined in normal subjects, 1 callosotomy patient, and 4 patients with intractable epilepsy. Twenty-five right-handed subjects were more likely to demonstrate an influence of a mouthed word on identification of a dubbed acoustic word when the speaker's face was lateralized to the LVF as compared with the RVF. In contrast, display of printed response alternatives in the RVF elicited a greater percentage of McGurk responses than display in the LVF. Visual field differences were absent in a group of 15 left-handed subjects. These results suggest that in right-handers, the two hemispheres may make distinct contributions to the McGurk effect. The callosotomy patient demonstrated reliable McGurk effects, but at a lower rate than the normal subjects and the epileptic control subjects. These data support the view that both the right and left hemisphere can make significant contributions to the McGurk effect. 相似文献
20.
H. O. Menlove M. M. Fowler E. Garcia M. C. Miller M. A. Paciotti R. R. Ryan S. E. Jones 《Journal of Fusion Energy》1990,9(4):495-506
Experiments using high-efficiency neutron detectors have detected neutron emission from various forms of Pd and Ti metal in pressurized D2 gas cells and D2O electrolysis cells. Four independent neutron detectors based on3He gas tubes were used. Both random neutrons (0.05–0.2 n/s) and time-correlated neutron bursts (10–280 n) of 100-s duration were measured using time-correlation counting techniques. The majority of the neutron burst events occurred at –30°C as the samples were warming up from the liquid nitrogen temperature. 相似文献