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排序方式: 共有2070条查询结果,搜索用时 15 毫秒
101.
FM Hisama J Oshima CE Yu YH Fu J Mulligan SM Weissman GD Schellenberg 《Canadian Metallurgical Quarterly》1998,52(3):352-357
OBJECTIVE: The audiologic presentation of vestibular schwannoma (VS) associated with neurofibromatosis type 2 (NF2) has not been well characterized. The goal of this study was to investigate the audiologic features of NF2-associated VS and to determine their relationship to the size of the tumor. STUDY DESIGN: A retrospective case review. SETTING: Quaternary governmental medical research institute evaluating patients fitting specific criteria for ongoing clinical studies. PATIENTS: Audiologic and magnetic resonance imaging data were available for 40 patients (25 males, 15 females), with an average age of 32 years, who had been recruited for ongoing clinical and genetic studies of NF2. MAIN OUTCOME MEASURES: The audiologic profile and magnetic resonance imaging characteristic of tumor were retrospectively reviewed. RESULTS: The average size of the tumor at presentation was 7.26 +/- 16.58 cm3 and measured 1.2, 1.6, and 1.1 cm in the anterior/posterior, lateral/medial, and superior/inferior dimensions, respectively. An increase in lateral/medial size of the tumor most significantly correlated with deterioration in mid- (1,000-2,000 Hz) and high- (4,000-8,000 Hz) frequency hearing levels, elevated speech reception threshold, and prolonged auditory brain stem response waves III and V latency. CONCLUSIONS: Patients with NF2 demonstrate a more predictable audiologic profile for a given size tumor than has been previously described with spontaneous or sporadic VS. 相似文献
102.
103.
104.
Sheppard J.W. Kaufman M.A. 《IEEE transactions on instrumentation and measurement》2005,54(3):1003-1018
Accounting for the effects of test uncertainty is a significant problem in test and diagnosis, especially within the context of built-in test. Of interest here, how does one assess the level of uncertainty and then utilize that assessment to improve diagnostics? One approach, based on measurement science, is to treat the probability of a false indication [e.g., built-in-test (BIT) false alarm or missed detection] as the measure of uncertainty. Given the ability to determine such probabilities, a Bayesian approach to diagnosis, and by extension, prognosis suggests itself. In the following, we present a mathematical derivation for false indication and apply it to the specification of Bayesian diagnosis. We draw from measurement science, reliability theory, signal detection theory, and Bayesian decision theory to provide an end-to-end probabilistic treatment of the fault diagnosis and prognosis problem. 相似文献
105.
Irving Kaufman Pan-Tze Chang Hsueh-Shun Hsu Wen-Yuan Huang Daw-Yang Shyong 《Journal of Nondestructive Evaluation》1987,6(2):87-100
This paper discusses surface crack detection by photothermal radiometric imaging (PRI). In PRI, also called dynamic infrared scanning, a surface is scanned with a spot of heat. Imperfections are detected by radiometrically sensing changes in the surface temperature of a small area in the vicinity of this spot. In the work described, cracks narrower than 25 µm (0.001 in.) in a lightly rusted steel surface have been detected. Indiscrete scanning an amplitude modulated heating beam is moved in steps, remaining at each location long enough to measure amplitude and phase of the AC temperature. Incontinuous scanning a constant intensity heating beam is moved continuously while the temperature deviations are measured. This paper presents methods of calculating amplitude and phase of surface temperature for discrete scanning and instantaneous temperature for continuous scanning across a surface crack. For a steel surface scanned by a watt-level laser beam, predicted surface temperature deviations when crossing the crack are several degrees Celsius, with expected radiometrically detected power several orders of magnitude above the detector noise. In experiments performed, both techniques easily detected narrow cracks in a smooth, clean surface. Discolorations and pits, on the other hand, generate a disturbing type of surface noise. This noise was minimized by differential detection. Based on results obtained, continuously scanned PRI with a fan-type heating beam and array detection could become a viable way of mapping surface cracks at practical scanning speeds. 相似文献
106.
The effects of age and gender on the single dose pharmacokinetics of avitriptan and its three metabolites were assessed in 15 young men, 15 young women, 15 elderly men and 15 elderly women. Avitriptan was administered as a 150-mg capsule after a 10-hour fast and serial plasma and urine samples were collected up to 36 hours after the dose. Plasma samples were analyzed for avitriptan and its metabolites, N-desmethyl avitriptan (ND048), O-desmethyl avitriptan (OD048), and methoxypyrimidinyl piperazine (MPP). Urine samples were analyzed for only avitriptan and MPP. Avitriptan was well tolerated in all four groups. The drug was rapidly absorbed with a median time to maximum plasma concentration (tmax) between 0.5 and 1.5 hours. No significant gender-related differences were found in the maximum plasma concentration (Cmax) and area under the concentration-time curve extrapolated to infinity (AUC0-infinity) of avitriptan. Renal clearance of avitriptan was significantly smaller in young women compared with young men, but this is clinically not relevant because only 2% to 3% of the total dose is excreted unchanged. Compared with the young volunteers, mean Cmax was approximately 50% higher in the elderly but there was no difference in the AUC0-infinity between the 2 age groups. Plasma concentrations of ND048, OD048, and MPP were each 50 to 100 fold lower than those of avitriptan. Hence some age- and gender-related differences found in the pharmacokinetics of avitriptan metabolites are probably not relevant in the assessment of overall safety and efficacy of avitriptan. Based on the pharmacokinetics and tolerability, no age or gender-related dose adjustment is necessary for avitriptan. 相似文献
107.
The influence of coking-product pyrolysis within the coke furnace on the phenol content in coal tar and in the water in the gas-collection cycle and at the biochemical-treatment unit is considered. 相似文献
108.
DG Standaert CM Testa GD Rudolf ZR Hollingsworth 《Canadian Metallurgical Quarterly》1996,276(1):342-352
N-methyl-D-aspartate (NMDA) glutamate receptors have an established role in the regulation of motor behavior by the basal ganglia. Recent studies have revealed that NMDA receptors are heteromeric assemblies of structurally related subunits from two families: NMDAR1, which is required for channel activity, and NMDAR2A-D, which modulate the properties of the channels. In the rat, the NMDA receptor subunits exhibit anatomically restricted patterns of expression, so that each component of the basal ganglia has a distinct NMDA receptor subunit mRNA phenotype. We have used in vivo intrastriatal injection of synthetic antisense oligodeoxynucleotides (ODNs) to examine the roles of particular NMDA receptor subunits in the regulation of motor behavior in rats. Injection of 15 nmol of a 20-mer ODN targeted to the NMDAR1 subunit induced spontaneous ipsilateral rotation. Smaller doses of NMDAR1 antisense ODN did not lead to spontaneous rotation, but prominent ipsilateral rotation was observed after systemic administration of D-amphetamine. An antisense ODN to NMDAR2A was also effective in eliciting amphetamine-inducible rotation, although the magnitude of the effect was less than that seen with NMDAR1, whereas ODNs targeted to NMDAR2B, NMDAR2C and an NMDAR1 sense strand ODN had no effect on behavior. In situ hybridization demonstrated that injection of the NMDAR1, NMDAR2A or NMDAR2B antisense ODNs produced specific reductions in target mRNA signal intensity in the injected striatum. After NMDAR1 antisense ODN injection, striatal binding of 3H-glutamate target mRNA signal intensity in the injected striatum. After NMDAR1 antisense ODN injection, striatal binding of 3H-glutamate to NMDA sites was not altered, although strychnine-insensitive 3H-glycine binding sites exhibited a small but significant reduction. These observations suggest that NMDA receptor complexes containing NMDAR1 and, to a lesser extent, NMDAR2A subunits play particularly important roles in the regulation of motor behavior by neostriatal neurons. 相似文献
109.
Careful granulometric preparation of coal samples is required. The sample must contain no more than 30% of the ≤0.5 mm class. The preparation of the plastometric equipment for testing is also considered. 相似文献
110.
TR Ulich J del Castillo G Senaldi E Cheung L Roskos J Young G Molineux J Guo J Schoemperlen L Munyakazi R Murphy-Filkins JE Tarpley CF Toombs S Kaufman S Yin AG Nelson JL Nichol WP Sheridan 《Canadian Metallurgical Quarterly》1999,27(1):117-130
A single injection of > or =10 microg/kg PEG-rHuMGDF in mice causes a dose-dependent increase in circulating platelets beginning on day 3 and peaking on days 5-6. The mean platelet volume and platelet distribution width at doses > or =100 microg/kg initially increase in a dose-dependent fashion and later decrease. However, the mean platelet volume does not change when platelets are incubated with PEG-rHuMGDF in vitro. The number of marrow megakaryocytes increases in a dose-dependent fashion as early as day 1 and peaks on day 3. Marrow megakaryocyte colony-forming units (CFU-Meg) do not increase on days 1-3 at a dose of 100 microg/kg (a dose that increases platelet numbers two- to threefold and may be clinically relevant), but the relative frequency of high ploidy megakaryocytes and the proportion of large marrow megakaryocytes (29-50 microm in diameter) increases. After a dose of 1,000 microg/kg the percentage of megakaryocytes in mitosis peaks at 24-48 hours and the percentage of megakaryocytes incorporating BrdU is maximal at 48 hours, the relatively delayed peak of BrdU incorporation most likely representing endomitosis. The relative frequency of type II and III megakaryocytes peaks on days 3 and 4, respectively. Pharmacokinetic analysis of PEG-rHuMGDF shows peak serum concentrations at 2-4 hours and a terminal half-life of 11.4+/-2.5 hours. A single injection of PEG-rHuMGDF ameliorates carboplatin-induced megakaryocytopenia and thrombocytopenia in a dose-response dependent fashion. In conclusion, a single injection of PEG-rHuMGDF increases megakaryocyte and platelet production in normal and myelo-suppressed mice. 相似文献