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1.
Barbara M. Johnston Peter R. Johnston 《International journal for numerical methods in engineering》2003,56(4):589-607
Accurate numerical evaluation of integrals arising in the boundary element method is fundamental to achieving useful results via this solution technique. In this paper, a number of techniques are considered to evaluate the weakly singular integrals which arise in the solution of Laplace's equation in three dimensions and Poisson's equation in two dimensions. Both are two‐dimensional weakly singular integrals and are evaluated using (in a product fashion) methods which have recently been used for evaluating one‐dimensional weakly singular integrals arising in the boundary element method. The methods used are based on various polynomial transformations of conventional Gaussian quadrature points where the transformation polynomial has zero Jacobian at the singular point. Methods which split the region of integration into sub‐regions are considered as well as non‐splitting methods. In particular, the newly introduced and highly accurate generalized composite subtraction of singularity and non‐linear transformation approach (GSSNT) is applied to various two‐dimensional weakly singular integrals. A study of the different methods reveals complex relationships between transformation orders, position of the singular point, integration kernel and basis function. It is concluded that the GSSNT method gives the best overall results for the two‐dimensional weakly singular integrals studied. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
2.
TP Hopp 《Canadian Metallurgical Quarterly》1995,4(9):1851-1859
Evidence is presented that the cytoplasmic domain of the type I interleukin-1 receptor (IL-1R) may be a GTPase. This domain conserves segments of hydrophobic amino acids that suggest a structural relatedness to the ras protooncogene protein and other members of the GTPase superfamily, despite a lack of significant detectable sequence homology. When the hydrophobic segments of the IL-1R were aligned with similar segments of the GTPases, it became apparent that the IL-1Rs possess a number of conserved amino acids that represent plausible functional residues for base-specific binding of GTP, magnesium chelation, and phosphate ester hydrolysis. Furthermore, a segment of five contiguous residues were found that is identical between ras and the IL-1R, and which is positioned to form part of the guanine base binding pocket. If this model is correct, then the IL-1Rs possess a highly conserved effector protein binding region, but one that is entirely unrelated to the effector regions of other superfamily members. Therefore, if the IL-1R is indeed a GTPase, then its activation function may be directed to as-yet unrecognized effector target proteins, as part of a unique cellular signal transduction pathway. 相似文献
3.
Pre-transplant nephrectomy was done in a 25-year-old man for calculous pyelonephritis using a retroperitoneal laparoscopic approach with a newly devised ligature applicator-dissector- kidney retractor. 相似文献
4.
The evaluation of microcomputer programs: an area of debate 总被引:1,自引:0,他引:1
V. M. Johnston 《Journal of Computer Assisted Learning》1987,3(1):40-50
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Letters to the editor 总被引:1,自引:0,他引:1
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[Correction Notice: An erratum for this article was reported in Vol 31(2) of Canadian Psychology Psychologie Canadienne (see record 2007-08913-001). In the October 1989 issue (Vol. 30, No. 4, p. 697), Arnold Rincover's affiliation with the Ontario Institute for Studies in Education was incorrectly given as Associate Professor. He has been an Extramural Instructor at O.I.S.E.] Reviews the book, The parent-child connection by Arnold Rincover (1988). The parent-child connection is a well written book that offers valuable advice to help parents of young children evaluate and understand their children's behaviour. It also offers useful suggestions on managing child behaviour, although these parenting tips are most likely to be useful to those parents who least need them (i.e., those with numerous personal and social resources, whose children are presenting only minor behavioural difficulties). The two general themes of the book, child behaviour as communication and developmental norms as guidelines for deciding if behaviour is problematic, are well-suited to the purposes of a parent reference book. They offer an appropriate framework for discussing specific child behaviours and helping parents to determine if these behaviours are problematic in their children. This book is a welcome addition to the list of available parenting books, and may prove particularly useful for younger parents in need of accurate and understandable information about normal child development and behaviour. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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PURPOSE: Ultrasound estimated bladder weight was compared before and after surgery for benign prostatic hyperplasia (BPH) to reveal a possible reversible change in bladder hypertrophy. MATERIALS AND METHODS: Ultrasound estimated bladder weight was measured before and after subcapsular (17) or transurethral (16) prostatectomy in 33 male patients with BPH. Sequential changes in the American Urological Association symptom score and urinary flow rate were also examined. RESULTS: Along with a significant improvement in the American Urological Association symptom scores and maximum flow rate, ultrasound estimated bladder weight decreased from 52.9 +/- 22.6 to 31.6 +/- 15.8 gm. in 12 weeks after treatment. In all but 4 patients (29 of 33, or 87.9%) ultrasound estimated bladder weight decreased to less than 35.0 gm. in 12 weeks after treatment. Interestingly, in all patients with an initial ultrasound estimated bladder weight of greater than 80 gm. the bladder weight still remained at an abnormally high level 12 weeks after treatment. CONCLUSIONS: Bladder hypertrophy was completely reversible after the surgical treatment of the obstruction in the majority of patients with BPH. The measurement of ultrasound estimated bladder weight was of value in monitoring therapeutic effects in BPH patients. An extraordinarily high ultrasound estimated bladder weight of 80 gm. or more might suggest degenerative and irreversible pathological changes in the bladder detrusor. 相似文献
9.
This article reviews the current status and future prospects for glass-ionomer materials. These materials are of two chemical types: the older, self-hardening cements, which set by an acid-base neutralization reaction to give relatively brittle materials; and the newer, resin-modified cements, which set partly by polymerization and partly by neutralization. Compared with the self-hardening cements, the latter materials have improved esthetics, improved resistance to moisture, and greater toughness. Both types of glass-ionomer cement bond well to enamel and dentin and release a clinically useful amount of fluoride. They have been used in a variety of applications: as liners or bases, for luting of stainless steel crowns, for Class V restorations in permanent teeth, and for Class II and Class III restorations in primary teeth. The resin-modified glass-ionomers are particularly promising for these latter uses, although it is too early to be sure whether their long-term durability is sufficient. Self-hardening glass-ionomer materials are likely to retain specific niches of clinical application, including in their metal-reinforced and cermet-containing forms. 相似文献
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