| 1. |
- Bertoni, Marco, et al.
(author)
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The Rise of Social Product Development
- 2012
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In: International Journal of Networking and Virtual Organisations. - Australia : Inderscience Publishers. - 1741-5225 .- 1470-9503. ; 11:2, s. 188-207
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Journal article (peer-reviewed)abstract
- The aim of the paper is to discuss the rising potential of social software to increase the knowledge management capabilities of virtual product development teams. It presents six fundamental transitions, elaborated from the empirical findings, which justify the rise of a more bottom-up, social creation and sharing of engineering knowledge in the virtual organisation. The study suggests that traditional engineering knowledge management approaches alone are not sufficient to support development activities in the virtual organisation, and that such teams display an increasing demand for social, comparatively lightweight and remixable platforms for bottom-up, social creation and sharing of knowledge.
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| 2. |
- Dahlgren, Annika, 1964, et al.
(author)
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Linking the Klein-Bell ADL Scale to the International Classification of Functioning, Disability, and Health (ICF) : Linking an ADL scale to the ICF
- 2013
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In: Journal of Rehabilitation Medicine. - : Medical Journals Sweden AB. - 1650-1977. ; 45:4, s. 351-7
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Journal article (peer-reviewed)abstract
- Objective: The main objective of this study was to link the Klein-Bell Activities of Daily Living (KB) Scale to the International Classification of Functioning, Disability and Health (ICF), in order to validate the KB Scale content-wise. Design: A qualitative approach was used with directed content analysis. Methods: Concepts in the KB Scale items were linked to ICF categories according to established rules. This was followed by 4 analyses: examination of the linked categories' frequency distribution; comparison of these categories with Core Sets for spinal cord injury (SCI) and occupational therapists; calculation of content density, content diversity and range of linked categories; and calculation of agreement between two independent linkage versions. Results: All except one identified KB Scale concept could be linked to ICF categories. The occupational therapists Core Sets were most consistent with linked categories in the KB Scale. Content density, content diversity and range varied between the different KB Scale dimensions. Agreement was reliable for the whole KB Scale and for 5 of 6 dimensions. Conclusion: The ICF has provided a valuable reference to identify and quantify the concepts in the KB Scale. Furthermore, comparison between the KB Scale and ICF Core Sets provides insights into areas covered by these instruments.
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| 3. |
- Ericson, Åsa, et al.
(author)
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Expanding the social dimension - Towards a knowledge base for product-service innovation
- 2011
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In: Impacting society through engineering design. - Glasgow : Design Research Society. - 9781904670230 ; , s. 143-152
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Conference paper (peer-reviewed)abstract
- The extension of businesses to incorporate the provision of function as a service in supplement to standalone products is an ongoing movement in manufacturing industry. In short, this means that the development intent should be guided by the need of ‘performance in use’ that the customer wants, e.g. thrust rather than an engine. By this, the established knowledge base challenges the development team. This paper embarks from the assumption that there are three main challenges, i.e. (1) innovation activities, (2) customer data acquisition and (3) the transformation of data into design information. The purpose is to discuss knowledge sharing activities to contribute to product-service innovation. In this study it has been found that contemporary data acquisition activities filter out important dimensions of knowledge. Thus, does not provide a sound base for service provisions.
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| 4. |
- Ericson, Åsa, et al.
(author)
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Revisiting the Research Field of Product-Service Systems Development
- 2012
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In: Proceedings of the ASME 2012 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference : IDETC/CI. - New York : American Society of Mechanical Engineers. - 9780791845028 ; 3, s. 1043-1049
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Conference paper (peer-reviewed)abstract
- The research within the Product-Service Systems (PSS) field aims to support manufacturing industries’ ability to provide value in terms of a service offer to its customers, simultaneously taking a more holistic approach to eco-sustainability. The industrial idea of providing customer benefits in parallel with robust products is not new, yet equipping engineers to conduct innovation and applying a service perspective in the early design stages is noticed as fairly radical. The purpose in this paper is two-fold. First, to describe research efforts within the PSS field seen through our engineering design lenses, second, to explore and discuss plausible directions and by that identify “white spots” on the map, which may be seen as relevant directions for futureresearch.
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| 5. |
- Holm, Åsa, et al.
(author)
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A linear programming model for optimizing HDR brachytherapy dose distributions with respect to mean dose in the DVH-tail
- 2013
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In: Medical physics (Lancaster). - : American Association of Physicists in Medicine. - 0094-2405. ; 40:8
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Journal article (peer-reviewed)abstract
- Purpose: Recent research has shown that the optimization model hitherto used in high-dose-rate (HDR) brachytherapy corresponds weakly to the dosimetric indices used to evaluate the quality of a dose distribution. Although alternative models that explicitly include such dosimetric indices have been presented, the inclusion of the dosimetric indices explicitly yields intractable models. The purpose of this paper is to develop a model for optimizing dosimetric indices that is easier to solve than those proposed earlier. less thanbrgreater than less thanbrgreater thanMethods: In this paper, the authors present an alternative approach for optimizing dose distributions for HDR brachytherapy where dosimetric indices are taken into account through surrogates based on the conditional value-at-risk concept. This yields a linear optimization model that is easy to solve, and has the advantage that the constraints are easy to interpret and modify to obtain satisfactory dose distributions. less thanbrgreater than less thanbrgreater thanResults: The authors show by experimental comparisons, carried out retrospectively for a set of prostate cancer patients, that their proposed model corresponds well with constraining dosimetric indices. All modifications of the parameters in the authors model yield the expected result. The dose distributions generated are also comparable to those generated by the standard model with respect to the dosimetric indices that are used for evaluating quality. less thanbrgreater than less thanbrgreater thanConclusions: The authors new model is a viable surrogate to optimizing dosimetric indices and quickly and easily yields high quality dose distributions.
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| 6. |
- Holm, Åsa
(author)
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Dose Plan Optimization in HDR Brachytherapy using Penalties : Properties and Extensions
- 2011
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Licentiate thesis (other academic/artistic)abstract
- High dose-rate (HDR) brachytherapy is a specific type of radiotherapy used to treat tumours of for example the cervix, prostate, and breasts. In HDR brachytherapy applicators are implanted into or close to the tumour volume. A radioactive source is moved through these applicators and stops at certain positions, known as dwell points. For each patient an anatomy-based dose plan is created that decides for example where to place the applicators, which dwell points to use, and for how long. The aim when creating a dose plan is to deliver an as high dose as possible to the tumour while simultaneously keeping the dose to the surrounding healthy organs as low as possible.In order to improve the quality of dose plans mathematical optimization methods are today used in clinical practice. Usually one solves a linear penalty model that minimizes a weighted deviation from dose intervals provided by a physician. In this thesis we study certain properties and alterations of this model.One interesting property of the model that we study is the distribution of the basic variables. We show that due to the distribution of these variables only a limited number of dwell positions can be used. Since relatively few dwell positions are used some of the corresponding dwell times have to be long in order for the desired overall dose level to be reached. These long dwell times have been observed in clinical practice and are considered to be a problem.Another property that we study is the correlation between the objective value of the linear penalty model and dose-volume parameters used for evaluation of dose plans. We show that the correlation is weak, which implies that optimizing the linear penalty model does not give a solution to the correct problem.Some alternative models are also considered. One that includes into the optimization the decision of where to place the applicators, when HDR brachytherapy is applied for prostate cancer, and one that reduces the long dwell times by using piecewise linear penalties. The solutions to both models show significant improvements.
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| 7. |
- Holm, Åsa, et al.
(author)
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Impact of Using Linear Optimization Models in Dose Planning for HDR Brachytherapy
- 2012
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In: Medical physics (Lancaster). - : American Association of Physicists in Medicine. - 0094-2405. ; 39:2, s. 1021-1028
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Journal article (peer-reviewed)abstract
- Purpose: Dose plans generated with optimization models hitherto used in HDR brachytherapy have shown a tendency to yield longer dwell times than manually optimized plans. Concern has been raised for the corresponding undesired hot spots and various methods to mitigate these have been developed. The hypotheses of this work are a) that one cause for the long dwell times is the use of objective functions comprising simple linear penalties and b) that alternative penalties, being piecewise linear, would lead to reduced length of individual dwell times.Methods: The characteristics of the linear penalties and the piecewise linear penalties are analysed mathematically. Experimental comparisons between the two types of penalties are carried out retrospectively for a set of prostate cancer patients.Results: While most dose-volume parameters do not differ significantly between the two types of penalties significant changes can be seen in the dwell times. On the average, total dwell times were reduced by 4.2%, with a reduction of maximum dwell times by 30%, using the alternative penalties.Conclusion: The use of linear penalties in optimization models for HDR brachytherapy is one cause for undesired longer dwell times appearing in mathematically optimized plans. By introducing alternative penalties significant reduction in dwell times can be achieved for HDR brachytherapy dose plans. Although various constraints as to reduce the long dwell times have been developed our finding is of fundamental interest in showing the shape of the objective function to be one reason for their appearance.
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| 8. |
- Holm, Åsa
(author)
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Mathematical Optimization of HDR Brachytherapy
- 2013
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Doctoral thesis (other academic/artistic)abstract
- One out of eight deaths throughout the world is due to cancer. Developing new treatments and improving existing treatments is hence of major importance. In this thesis we have studied how mathematical optimization can be used to improve an existing treatment method: high-dose-rate (HDR) brachytherapy.HDR brachytherapy is a radiation modality used to treat tumours of for example the cervix, prostate, breasts, and skin. In HDR brachytherapy catheters are implanted into or close to the tumour volume. A radioactive source is moved through the catheters, and by adjusting where the catheters are placed, called catheter positioning, and how the source is moved through the catheters, called the dwelling time pattern, the dose distribution can be controlled.By constructing an individualized catheter positioning and dwelling time pattern, called dose plan, based on each patient's anatomy, it is possible to improve the treatment result. Mathematical optimization has during the last decade been used to aid in creating individualized dose plans. The dominating optimization model for this purpose is a linear penalty model. This model only considers the dwelling time pattern within already implanted catheters, and minimizes a weighted deviation from dose intervals prescribed by a physician.In this thesis we show that the distribution of the basic variables in the linear penalty model implies that only dwelling time patterns that have certain characteristics can be optimal. These characteristics cause troublesome inhomogeneities in the plans, and although various measures for mitigating these are already available, it is of fundamental interest to understand their cause.We have also shown that the relationship between the objective function of the linear penalty model and the measures commonly used for evaluating the quality of the dose distribution is weak. This implies that even if the model is solved to optimality there is no guarantee that the generated plan is optimal with respect to clinically relevant objectives, or even near-optimal. We have therefore constructed a new model for optimizing the dwelling time pattern. This model approximates the quality measures by the concept conditional value-at-risk, and we show that the relationship between our new model and the quality measures is strong. Furthermore, the new model generates dwelling time patterns that yield high-quality dose distributions.Combining optimization of the dwelling time pattern with optimization of the catheter positioning yields a problem for which it is rarely possible to find a proven optimal solution within a reasonable time frame. We have therefore developed a variable neighbourhood search heuristic that outperforms a state-of-the-art optimization software (CPLEX). We have also developed a tailored branch-and-bound algorithm that is better at improving the dual bound than a general branch-and-bound algorithm. This is a step towards the development of a method that can find proven optimal solutions to the combined problem within a reasonable time frame.
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| 9. |
- Holm, Åsa, et al.
(author)
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Study of the Relationship Between Dosimetric Indices and Linear Penalties in Dose Distribution Optimization for HDR Prostate Brachytherapy
- 2013
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Other publication (other academic/artistic)abstract
- Purpose: Most clinical software for optimizing dwelling time patterns is based on a linear penalty model. The quality of a dose distribution generated by the dwelling time pattern is, however, evaluated through a number of dosimetric indices. The purpose of this article is to investigate the relationship between the linear penalty model and the dosimetric indices.Method and Materials: Data sets from three patients, previously treated for prostate cancer with HDR brachytherapy as a boost to external beam therapy, were used for this study, and for each of them 300 random dwelling time patterns were generated. The relationship between the linear penalty model and the dosimetric indices were studied both by the Pearson’s product moment correlation coefficient between the objective function value of the linear penalty model and the values of the dosimetric indices, and by scatter-grams.Results: For one of the three patients we found a clear connection between the linear penalty model and the values of the dosimetric indices, but not for the other two. For the two patients without a clear connection there where some dosimetric indices that actually improved with deteriorating objective function value.Conclusion: The dwelling time pattern found by using the linear penalty model does not correspond to the optimal dose distribution with respect to dosimetric indices.
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| 10. |
- Kastensson, Åsa, et al.
(author)
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Embracing risk to pursue product innovation in automotive industry
- 2010
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Conference paper (peer-reviewed)abstract
- A company’s ability to successfully introduce radically new products and services is a key success factor for sustaining competitive advantage. This is particularly true for the automotive industry, where smaller manufacturers with niche products struggle to compete with the large-scale efforts of their bigger competitors, and are thus in desperate need to innovate their way out of the current crisis. A key challenge for companies seeking innovation is how to better understand the role of risk in innovative practice. The purpose of this study is to investigate how managers within an automotive company perceive the concept of innovation and the relation between innovation and risk. The study is based on interviews with fifteen managers representing a cross-section of disciplines. The analysis of the informants’ answers resulted in two overarching themes, “novelty” and “value”, which were further broken down into seven sub-themes to highlight different facets of innovation that were raised by managers from these disciplines. While there were many similarities in the perceptions, the most striking differences related to; 1) innovation as being about the “combination of things to something new”, and 2) innovation as being about increasing “customer value”. Several informants noted that risk taking is a success factor to achieve innovation, but they also acknowledged that there are several inhibiting factors that are in contradiction with this approach, such as limited time and money. Further the paper has highlighted the crucial challenge of how to effectively balance risk and opportunity to invest in long-term opportunities, without risking short-term growth.
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