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81.
C. R. Lawson 《Geotextiles and Geomembranes》1992,11(4-6):431-448
The use of geotextiles as revetment filters comprised one of the earliest applications for these materials. In performing its role within the revetment structure the geotextile must meet specific mechanical and hydraulic criteria. The mechanical criteria presented in the paper are based on empirical relationships derived by correlating analysed in-situ performance with appropriate laboratory mechanical test methods. The hydraulic criteria presented in the paper rationalizes the plethora of published geotextile filter criteria, and consider such variables as geometric and hydrodynamic stability, mode of water movement through the geotextile filter, and type of foundation soil to be protected. 相似文献
82.
Saturated fractional factorial experimental designs and orthogonal main effect plans are extremely valuable tools in quality engineering. However, one problem with these designs is that there are no replicate runs to be used for estimating experimental error. This note develops an estimator of the experimental error based on the hypothesis that not all factor effects will be non-zero. A joint Bayesian prior distribution is presented for the experimental error variance of an effect, σ2, and the probability that each effect is non-zero. From this prior distribution a posterior marginal distribution for σ2 is derived along with a direct estimate of σ2. This method is compared with the traditional methods of estimating σ2 in unreplicated designs through a numerical example. 相似文献
83.
JC Ardern MJ Saunders K Hyde R Lawson JA Yin GS Lucas 《Canadian Metallurgical Quarterly》1993,7(2):258-262
The hypothesis that 'rare' variable number tandem repeat (VNTR) alleles of the Harvey ras (Ha-ras) locus are an inherited predisposing factor in myeloid malignancies has been evaluated. We describe an application of the polymerase chain reaction (PCR) which amplifies the VNTR region at the Ha-ras locus and offers a number of advantages over conventional Southern analysis. Ha-ras VNTR genotypes were assigned to 57 normal subjects, 46 patients with acute myeloid leukaemia (AML), 26 with myelodysplastic syndrome (MDS) and 49 with chronic granulocytic leukaemia (CGL). By comparison with previous reports we found significantly higher frequencies of rare alleles (20.2%) in our normal subjects of whom more than 35% had at least one 'rare' allele. The frequencies of rare alleles in the patient groups was not significantly different from the normal group (chi 2 = 0.54, p = 0.91). In studies of constitutional and leukaemic DNA from patients with AML, we found that allelic loss at the Ha-ras locus was not a common phenomenon. The improved resolution achievable with PCR compared with Southern analysis was demonstrated by the inability of Southern analysis to resolve six out of 34 PCR heterozygotes. We therefore suggest that previous studies showing linkage between rare Ha-ras alleles and susceptibility to malignancy should be reevaluated using our sensitive PCR technique. 相似文献
84.
The subreflector presented is built of an aggregate of rigid panels, which are controlled by a small number of actuators. An algorithm is described to calculate the actuator motions for a set of given surface distortions. It is assumed that the surface distortions, at different elevation angles, are known a priori. Geometrical optics is used to describe the aperture field distribution and to predict the improvement in performance. Computer modeling of main and subreflectors was used to test the design. This design is suggested for the improvement of a hypothetical radio telescope. In this example, it is predicted that the effective surface errors, due to gravitational distortions, may be reduced to 33% of their uncorrected level with a 48-plate subreflector. Compensation with other subreflector configurations is also investigated 相似文献
85.
Lawson Katherine R.; Ruff Holly A.; McCarton-Daum Cecelia; Kurtzberg Diane; Vaughan Herbert G. Jr. 《Canadian Metallurgical Quarterly》1984,20(1):120
Compared older preterm and full-term infants in their response to objects in a dynamic multimodal context. In Study I, 67 12-wk-old full-term infants and 29 preterm infants (mean age 90 days) served as Ss. After familiarization with a silent moving object, full-term Ss recognized the object when it was stationary. When sound accompanied the moving object during familiarization, full-term Ss showed increased attention to the object but no subsequent recognition of that object. Neither high- nor low-risk preterms, at a comparable conceptional age, recognized the objects under any condition, but the low-risk preterms did show greater attention to the moving objects with sound. In Study II, 43 preterm Ss were tested approximately 6 mo after their estimated term date. The performance of the low-risk preterms was the same as that of full-terms; that is, through differential responding, they demonstrated association of an object and sound. In contrast, the high-risk preterms showed no differential looking. Thus both low- and high-risk preterms showed less differential responding than did normal full-terms at 3 mo, but at 6 mo only the high-risk preterms were different from the full-terms. Results suggest that the high-risk preterms are at a disadvantage for learning about the dynamic and multimodal aspects of their environment. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
86.
PH Hawley JJ Ronco SA Guillemi J Quieffin JA Russell LM Lawson MT Schechter JS Montaner 《Canadian Metallurgical Quarterly》1994,106(5):1456-1459
BACKGROUND: Although expression of the HER-2/neu oncogene may be of some prognostic importance in advanced ovarian cancer, its role in early-stage disease has not been established. The current study examined the prevalence and significance of HER-2/neu expression in early epithelial ovarian cancer. METHODS: The authors analyzed the expression of HER-2/neu on frozen tumor specimens from 40 patients with early epithelial ovarian cancer using the indirect immunoperoxidase technique with monoclonal antibodies that detect epitopes on the extracellular domain of the HER-2/neu protein. All patients underwent comprehensive surgical staging. HER-2/neu expression was graded as negative, weak, moderate (1+ to 2+), or strong (3+). Complete clinical data and long-term follow up were available for all patients. RESULTS: The distribution of patients by stage was as follows: Stage IA, 6; IB, 0; IC, 14; IIA, 4; IIB, 6; IIC, 10. The mean patient age was 53 years. Fourteen patients had serous tumors; nine, endometrioid; eight, clear cell; eight, mucinous; and one, undifferentiated. Intratumoral heterogeneity of HER-2/neu expression was observed with most specimens. In eight specimens (20%), some areas of the tumor showed strong (3+) expression, beyond the level that can be seen in normal ovarian epithelium. Twenty-eight specimens (70%) showed moderate (1+ to 2+) staining, whereas four specimens (10%) showed negative or weak staining. At a mean follow-up time among surviving patients of 32 months, 15 patients (37%) have had cancer recurrence. No statistically significant relationship was found between HER-2/neu expression and survival, disease-free survival, stage, or grade. A significant increase was found in 3+ expression of HER-2/neu in clear cell tumors. CONCLUSION: Consistent HER-2/neu overexpression occurs infrequently in early ovarian cancer, making it unlikely that such overexpression is a general early event in ovarian carcinogenesis. HER-2/neu expression does not appear to be a strong prognostic marker in early epithelial ovarian cancer. 相似文献
87.
Lead has been extracted from chloride solutions into kerosene containing excess di(2-ethylhexyl)phosphoric acid, using various concentrations of metal and extractant. Extraction proceeded readily, but the results indicated that 1.6 hydrogen ions were exchanged per atom of lead extracted, rather than 2.0 as would be expected for a divalent metal ion. Extraction was unaffected by metal concentration over the range studied (0.1–1.0 g l?1), and the results were highly consistent. The unique log D vs. pH relation allowed simple collection of data for contact stage evaluation by rearrangement of the familiar solvent extraction equations and use of empirically derived constants. An S-shaped extraction isotherm resulted, which limits the ease with which aqueous lead concentrations may be reduced by extraction with di(2-ethylhexyl)phosphoric acid. 相似文献
88.
The variation of the superconducting transition temperature for some ternary molybdenum sulfides (Chevrel phase) has been investigated as a function of hydrostatic pressure up to 22 kbar. The effects of pressure on Tc are the largest yet reported for any set of compounds. 相似文献
89.
Information system complexity is related to many software engineering metrics. Design, construction and maintenance difficulty can be associated with their respective complexity metrics. Complexity measurement algorithms for information system schemas are considered. A set of properties is proposed that serve as a basis for complexity assessment throughout the life cycle. Heretofore, an emphasis in system engineering has been the analysis of software program complexity. Current work, as well as new alternative measures, in software complexity are discussed. Complexity measurement is extended to include other major phases of the system life cycle. Benefits include the evaluation of complexity propagation between system development life cycle phases. Complexity projection provides for improved management of the development process. The implementation of the Dynamic Complexity Monitor (DYCOM) is discussed. DYCOM is comprised of analyzers and models useful in both research and industrial environments. DYCOM supports complexity assessment for requirement definitions, logical and physical design schemata, and implementation and maintenance. The system determines complexity projection functions between life cycle phases. Further, projection functions are automatically updated as the system is used. DYCOM “learns” from system development experience. Also, proposed complexity models can easily be added to DYCOM in order to evaluate their utility. DYCOM serves as a laboratory for examination of alternative complexity metrics. 相似文献
90.
Epidemiological studies indicating that nitrite inhalant abuse is a co-factor in HIV infection and in Kaposi's sarcoma are supported by recent experimental studies, described in this review. Inhalation exposure to the nitrites produce a nonspecific cytotoxicity, depleting many cells of the immune system. Apparently distinct from this cytotoxicity, inhalation of the nitrites impairs a variety of immune mechanisms, affecting both humoral and cell-mediated immunity. In addition, the inhalant-increased macrophage production of the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha), can directly stimulate HIV replication and can also stimulate the growth of Kaposi's sarcoma cells. Thus, nitrite inhalants may impair immune resistance to infection and actively promote viral replication and tumor growth. 相似文献