| 1. |
- Andersson, Claes, 1987, et al.
(författare)
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Hierarchical models for epidermal nerve fiber data
- 2018
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Ingår i: Statistics in Medicine. - : Wiley. - 0277-6715 .- 1097-0258. ; 37:3, s. 357-374
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Tidskriftsartikel (refereegranskat)abstract
- While epidermal nerve fiber (ENF) data have been used to study the effects of small fiber neuropathies through the density and the spatial patterns of the ENFs, little research has been focused on the effects on the individual nerve fibers. Studying the individual nerve fibers might give a better understanding of the effects of the neuropathy on the growth process of the individual ENFs. In this study, data from 32 healthy volunteers and 20 diabetic subjects, obtained from suction induced skin blister biopsies, are analyzed by comparing statistics for the nerve fibers as a whole and for the segments that a nerve fiber is composed of. Moreover, it is evaluated whether this type of data can be used to detect diabetic neuropathy, by using hierarchical models to perform unsupervised classification of the subjects. It is found that using the information about the individual nerve fibers in combination with the ENF counts yields a considerable improvement as compared to using the ENF counts only. Copyright © 2017 John Wiley & Sons, Ltd.
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| 2. |
- Andersson, Claes, 1987
(författare)
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Spatial analysis and modeling of nerve fiber patterns
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diabetic neuropathy is a condition associated with diabetes affecting the epidermal nerve fibers (ENFs). This thesis presents analysis methods and models for ENF data, with two main puroposes: to find early signs of diabetic neuropathy and to characterize how this condition changes the nerve fiber structure. Early detection is of interest to be able to take measures to slow down the progression of the condition, and a more detailed description of the changes in the nerve fiber structure could improve the understanding of its underlying mechanisms. The ENF samples are mainly analyzed as point patterns, where the points are the locations where nerve fibers enter the epidermis or terminate. The analysis is partly based on existing summary statistics for point patterns, but we also propose a new summary statistic to quantify the proportion of the skin covered by the nerve fibers. Two cluster processes are introduced as models for the patterns consisting only of the locations where the nerve fibers enter the epidermis. For one of the models, a Bayesian hierarchical method for parameter estimation is proposed. A model for the end points is also presented, and non-spatial models for individual nerve fibers, which are used to perform unsupervised classification of the subjects. From the results we find that while all patterns are aggregated, the level of aggregation tends to increase with increased severity of the neuropathy. The results from the modeling indicate that the increased aggregation is caused by a decrease in the number of clusters, while the structure within clusters appears to be similar in all disease groups. The results from the non-spatial analysis indicate that the nerve fibers from healthy subjects tend to extend further than those from subjects with diabetic neuropathy. The use of methods and models developed in this thesis is not limited to ENF data, but can be applied to point pattern data in general. In particular, the models for the base point patterns and the methods for estimating the parameters of these models are contributions to the point process literature.
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| 3. |
- Andersson, Claes, 1973, et al.
(författare)
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Wickedness and the anatomy of complexity
- 2018
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Ingår i: Futures. - : Elsevier BV. - 0016-3287. ; 95, s. 118-138
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Tidskriftsartikel (refereegranskat)abstract
- Traditional scientific policy approaches and tools are increasingly seen as inadequate, or even counter-productive, for many purposes. In response to these shortcomings, a new wave of approaches has emerged based on the idea that societal systems are irreducibly complex. The new categories that are thereby introduced – like “complex” or “wicked” – suffer, however, by a lack of shared understanding. We here aim to reduce this confusion by developing a meta-ontological map of types of systems that have the potential to “overwhelm us”: characteristic types of problems, attributions of function, manners of design and governance, and generating and maintaining processes and phenomena. This permits us, in a new way, to outline an inner anatomy of the motley collection of system types that we tend to call “complex”. Wicked problems here emerge as the product of an ontologically distinct and describable type of system that blends dynamical and organizational complexity. The framework is intended to provide systematic meta-theoretical support for approaching complexity and wickedness in policy and design. We also points to a potential causal connection between innovation and wickedness as a basis for further theoretical improvement.
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