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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Numerische Mathematik 73 (1996), S. 149-167 
    ISSN: 0945-3245
    Keywords: Mathematics Subject Classification (1991):65N30, 65F10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary. We consider two level overlapping Schwarz domain decomposition methods for solving the finite element problems that arise from discretizations of elliptic problems on general unstructured meshes in two and three dimensions. Standard finite element interpolation from the coarse to the fine grid may be used. Our theory requires no assumption on the substructures that constitute the whole domain, so the substructures can be of arbitrary shape and of different size. The global coarse mesh is allowed to be non-nested to the fine grid on which the discrete problem is to be solved, and neither the coarse mesh nor the fine mesh need be quasi-uniform. In addition, the domains defined by the fine and coarse grid need not be identical. The one important constraint is that the closure of the coarse grid must cover any portion of the fine grid boundary for which Neumann boundary conditions are given. In this general setting, our algorithms have the same optimal convergence rate as the usual two level overlapping domain decomposition methods on structured meshes. The condition number of the preconditioned system depends only on the (possibly small) overlap of the substructures and the size of the coarse grid, but is independent of the sizes of the subdomains.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Numerische Mathematik 66 (1993), S. 295-319 
    ISSN: 0945-3245
    Keywords: 65N20 ; 65F10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary The composite step biconjugate gradient method (CSBCG) is a simple modification of the standard biconjugate gradient algorithm (BCG) which smooths the sometimes erratic convergence of BCG by computing only a subset of the iterates. We show that 2×2 composite steps can cure breakdowns in the biconjugate gradient method caused by (near) singularity of principal submatrices of the tridiagonal matrix generated by the underlying Lanczos process. We also prove a “best approximation” result for the method. Some numerical illustrations showing the effect of roundoff error are given.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of advanced nursing 50 (2005), S. 0 
    ISSN: 1365-2648
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim.  This paper reports a study comparing the outcomes of diabetic patients undergoing either early discharge or routine care.Background.  The hospital is not the best place to monitor the glycaemic control of patients with diabetes with no other morbidity or complications. It is an unnatural environment in which diet is planned and the activity level is low. The hospital is also an expensive place in which to treat patients.Methods.  This randomized controlled trial was conducted in the medical department of a regional hospital in Hong Kong. A total of 101 patients who needed glycaemic monitoring, but who were otherwise fit for discharge, were recruited. The control group continued to receive routine hospital care. The study group was discharged early and received a follow-up programme which included a weekly or biweekly telephone call from a nurse.Findings.  When compared with the control group, the study group had a greater decrease in HbA1c at 24 weeks, although the statistical difference was marginal (7·6 vs. 8·1, P = 0·06), a higher blood monitoring adherence score at both 12 weeks (5·4 vs. 3·6, P 〈 0·001) and 24 weeks (5·3 vs. 3·5, P 〈 0·001), and a higher exercise adherence score at 12 weeks (5·3 vs. 3·4, P = 0·001) and 24 weeks (5·5 vs. 3·2, P 〈 0·001). The study group had a shorter hospital stay (2·2 vs. 5·9, P 〈 0·001), and the net savings were HK$11,888 per patient.Conclusion.  It is feasible to integrate treatment into the real life environments of patients with diabetes, and nurse-led transitional care is a practical and cost-effective model. Nurse follow-up is effective in maintaining optimal glycaemic control and enhancing adherence to health behaviours. Management of glycaemic control is better done in the community than in the hospital.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1365-2648
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim of the study.  To test the effects of music intervention on pre-operative anxiety in Chinese males undergoing transurethral resection of the prostate . Rationale.  No studies have measured the effects of music intervention in reducing pre-operative anxiety for patients with transurethral resection of the prostate (TURP). Previous studies have examined the effects of music on pre-operative anxiety but have not examined the possible effects of the presence of a carer as an independent variable in pre-operative anxiety levels of patients in addition to the music intervention. The cultural validity of applying a music intervention to the reduction of pre-operative anxiety was also investigated. Design.  A quasi-experimental design with three groups: music intervention, nurse presence and control group. Method.  Thirty patients having TURP were randomly assigned ( n  = 10 each group) to one of the three groups. Pre- and post-test measures of systolic and diastolic blood pressure, heart rate and state anxiety using the Chinese State-Trait Anxiety Inventory (C-STAI) were obtained for the three groups. Results.  The findings showed that the music intervention significantly reduced all blood pressure levels for the patients. A reduction in state anxiety level was also found for the music intervention group. No significant reductions in blood pressure, heart rate and state anxiety level were found in the nurse presence and control groups. Conclusion.  The results support the cross-cultural validity of using a music intervention in pre-operative anxiety reduction, in this case for TURP patients waiting in the theatre holding area.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1525-1446
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract  Assessing a combination of cardiovascular disease (CVD)-risk factors may be a practical tool for risk assessment and for finding the high-risk group among local community members. This study examines the association between the number of CVD-risk factors, regardless of any specific combination with the CVD ambit, using data from 1,570 residents in Tsing Yi community (Hong Kong) who registered with the Telehealth System. A quantitative composite CVD Risk Index (CVDRI) with scores ranging from 0 to 6 included rankings for high systolic and diastolic blood pressure, presence of diabetes, body mass index (BMI), smoking, and age. Multivariate logistic regression was used to estimate odds ratios for the prevalence of CVD. Those with a CVDRI of 1, 2, or 3 and above were 1.7 [95% confidence interval (CI) = 1.34–3.99], 5.3 (95% CI = 3.60–7.90), and 10 times (95% CI = 6.41–15.50) more likely to have CVD, respectively, than those with a risk index of 0. Among the CVDRI components, high blood pressure had the greatest influence on CVD risk, followed by presence of diabetes and high BMI. In conclusion, a CVDRI based on existing health data from a Telehealth System was developed and used to identify local community members at risk of CVD. Nurse intervention may achieve greater reduction of CVD morbidity and mortality if multiple risk factors for the high-risk group are addressed at the same time.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    BIT 32 (1992), S. 481-494 
    ISSN: 1572-9125
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We present algorithms for solving quadratically constrained linear least squares problems that do not necessarily require expensive dense matrix factorizations. Instead, only “black box” solvers for certain related unconstrained least squares problems, as well as the solution of two related linear systems involving the coefficient matrixA and the constraint matrixB, are required. Special structures in the problem can thus be exploited in these solvers, and iterative as well as direct solvers can be used. Our approach is to solve for the Lagrange multiplier as the root of an implicitly-defined secular equation. We use both a linear and a rational (Hebden) local model and a Newton and secant method. We also derive a formula for estimating the Lagrange multiplier which depends on the amount the unconstrained solution violates the constraint and an estimate of the smallest generalized singular value ofA andB. The Lagrange multiplier estimate can be used as a good initial guess for solving the secular equation. We also show conditions under which this estimate is guaranteed to be an acceptable solution without further refinement. Numerical results comparing the different algorithms are presented.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Numerical algorithms 7 (1994), S. 17-32 
    ISSN: 1572-9265
    Keywords: Lanczos method ; conjugate gradients squared algorithm ; breakdowns ; composite step ; 65F10 ; 65F25
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We propose a new and more stable variant of the CGS method [27] for solving nonsymmetric linear systems. The method is based on squaring the Composite Step BCG method, introduced recently by Bank and Chan [1,2], which itself is a stabilized variant of BCG in that it skips over steps for which the BCG iterate is not defined and causes one kind of breakdown in BCG. By doing this, we obtain a method (Composite Step CGS or CSCGS) which not only handles the breakdowns described above, but does so with the advantages of CGS, namely, no multiplications by the transpose matrix and a faster convergence rate than BCG. Our strategy for deciding whether to skip a step does not involve any machine dependent parameters and is designed to skip near breakdowns as well as produce smoother iterates. Numerical experiments show that the new method does produce improved performance over CGS on practical problems.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Numerical algorithms 9 (1995), S. 397-397 
    ISSN: 1572-9265
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Type of Medium: Electronic Resource
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