| 41. |
- Holmberg, Joakim, et al.
(författare)
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VerOpt - MATLAB Driven Versatile Optimization
- 2001
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Ingår i: Program and proceedings for the Nordic MATLAB Conference Oslo, October 17-18, 2001. - Trondheim : Comsol. - 8299595509 ; , s. 207-212
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- VerOpt, a MATLAB driven versatile optimization environment, enables the choice of a suitable optimization routine, parallelization over TCP/IP and the use of external solvers. VerOpt is the result of working towards the creation of a versatile yet effective environment for applied optimization studies. This paper presents the concepts behind VerOpt, including how and why we use parallelization, and the lessons learnt when using external solvers. The paper also gives a comparison of implemented optimization routines when applied to test problems. Currently, links to three external solvers are implemented. Two of them come from the commercial software market for engineering solutions: ANSYS (version 5.6 University High), a general purpose FE-code and C-MOLD (version 2000.7.1), a code for injection molding. The third solver is from the academic world, AnyBody, a code for biomechanical studies. The implemented optimization routines referred to are Method of Moving Asymptotes (MMA), Simulated Annealing (SA) and a genetic algorithm (GA). The MMA is a gradient-based algorithm whereas the other two can be classified as stochastic. The results of the comparison of the implemented optimization routines, in which �fmincon� from the MATLAB Optimization Toolbox is also used, show that MMA is generally the fastest routine, but does not always find the best solution. However, in test cases when parallelization is used the comparison is not ideal, since the parallelization procedures for the algorithms are not equivalent. When optimization routines are based on numerically computed gradients, such as MMA, they are embarrassingly parallel. This is because the gradients are independent of each other, which makes it possible to compute them simultaneously, but on different processors. For a stochastic routine such as SA a different approach is needed. In our case we have used a simple form of domain decomposition. An interesting result is that, in the test case involving ANSYS, we found that using ANSYS alone, as solver as well as optimizer, did not give such a good solution as using VerOpt. A clear future development is to add a greater number of different types of optimization routines. A possible future development is to transform VerOpt into something that is more akin to a regular style MATLAB Toolbox. Irrespective of this development, VerOpt will be a significant aid for education as well as research in applied optimization. It will also serve the authors as the environment for further research in the fields of injection molding and biomechanics.
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| 42. |
- Holmberg, Lars, et al.
(författare)
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A randomized trial comparing radical prostatectomy with watchful waiting in early prostate cancer
- 2002
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 347:11, s. 781-789
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Radical prostatectomy is widely used in the treatment of early prostate cancer. The possible survival benefit of this treatment, however, is unclear. We conducted a randomized trial to address this question. METHODS: From October 1989 through February 1999, 695 men with newly diagnosed prostate cancer in International Union against Cancer clinical stage T1b, T1c, or T2 were randomly assigned to watchful waiting or radical prostatectomy. We achieved complete follow-up through the year 2000 with blinded evaluation of causes of death. The primary end point was death due to prostate cancer, and the secondary end points were overall mortality, metastasis-free survival, and local progression. RESULTS: During a median of 6.2 years of follow-up, 62 men in the watchful-waiting group and 53 in the radical-prostatectomy group died (P=0.31). Death due to prostate cancer occurred in 31 of 348 of those assigned to watchful waiting (8.9 percent) and in 16 of 347 of those assigned to radical prostatectomy (4.6 percent) (relative hazard, 0.50; 95 percent confidence interval, 0.27 to 0.91; P=0.02). Death due to other causes occurred in 31 of 348 men in the watchful-waiting group (8.9 percent) and in 37 of 347 men in the radical-prostatectomy group (10.6 percent). The men assigned to surgery had a lower relative risk of distant metastases than the men assigned to watchful waiting (relative hazard, 0.63; 95 percent confidence interval, 0.41 to 0.96). CONCLUSIONS: In this randomized trial, radical prostatectomy significantly reduced disease-specific mortality, but there was no significant difference between surgery and watchful waiting in terms of overall survival.
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| 43. |
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| 44. |
- Holmberg, Lars
(författare)
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Desmopressin (DDAVP) and factor VIII
- 2003
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 1:9, s. 2046-2047
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 45. |
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| 46. |
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| 47. |
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| 48. |
- Holmberg, Lars, et al.
(författare)
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Pre-operative oestradiol levels - relation to survival in breast cancer
- 2001
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Ingår i: European Journal of Surgical Oncology. - : Elsevier BV. - 0748-7983 .- 1532-2157. ; 27:2, s. 152-156
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: There are clinical observations that operation during the luteal phase of the menstrual cycle (with high oestradiol levels) may positively influence prognosis in breast cancer. However, few studies have information on plasma levels of hormones pre-operatively. METHODS: We studied 774 women treated for breast cancer where plasma levels of oestradiol had been measured 1-2 days pre-operatively. Date and cause of death were ascertained from the files of the Swedish Cancer Register and 5434 person-years were observed. The endpoint was death with breast cancer as the underlying cause (n=41 and n=158 in the pre- and post-menopausal group, respectively). RESULTS: In life-table analyses, only pre-menopausal patients with oestradiol 500 pmol/l and above had a tendency (not statistically significant) for better survival. Multivariate Cox models with oestradiol modelled in continuous form yielded relative hazards (RH) close to unity in all women and in strata according to menopausal status. CONCLUSIONS: When oestradiol was analysed in categorized form, only women with the highest levels had a tendency for improved prognosis (RH around 0.7; not statistically significant). Moreover, this pattern was not apparent for pre-menopausal women. Our findings contradict the notion that the pre-operative oestradiol level is independently associated with breast cancer prognosis.
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| 49. |
- Holmberg, Lars, et al.
(författare)
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Stopping HABITS
- 2004
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Ingår i: Lancet. ; 363, s. 1476-
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Tidskriftsartikel (refereegranskat)
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| 50. |
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