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- Arnqvist, Per, 1963-
(author)
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Functional clustering methods and marital fertility modelling
- 2017
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Doctoral thesis (other academic/artistic)abstract
- This thesis consists of two parts.The first part considers further development of a model used for marital fertility, the Coale-Trussell's fertility model, which is based on age-specific fertility rates. A new model is suggested using individual fertility data and a waiting time after pregnancies. The model is named the waiting model and can be understood as an alternating renewal process with age-specific intensities. Due to the complicated form of the waiting model and the way data is presented, as given in the United Nation Demographic Year Book 1965, a normal approximation is suggested together with a normal approximation of the mean and variance of the number of births per summarized interval. A further refinement of the model was then introduced to allow for left truncated and censored individual data, summarized as table data. The waiting model suggested gives better understanding of marital fertility and by a simulation study it is shown that the waiting model outperforms the Coale-Trussell model when it comes to estimating the fertility intensity and to predict the mean and variance of the number of births for a population.The second part of the thesis focus on developing functional clustering methods.The methods are motivated by and applied to varved (annually laminated) sediment data from lake Kassj\"on in northern Sweden. The rich but complex information (with respect to climate) in the varves, including the shapes of the seasonal patterns, the varying varve thickness, and the non-linear sediment accumulation rates makes it non-trivial to cluster the varves. Functional representations, smoothing and alignment are functional data tools used to make the seasonal patterns comparable.Functional clustering is used to group the seasonal patterns into different types, which can be associated with different weather conditions.A new non-parametric functional clustering method is suggested, the Bagging Voronoi K-mediod Alignment algorithm, (BVKMA), which simultaneously clusters and aligns spatially dependent curves. BVKMA is used on the varved lake sediment, to infer on climate, defined as frequencies of different weather types, over longer time periods.Furthermore, a functional model-based clustering method is proposed that clusters subjects for which both functional data and covariates are observed, allowing different covariance structures in the different clusters. The model extends a model-based functional clustering method proposed by James and Suger (2003). An EM algorithm is derived to estimate the parameters of the model.
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| 2. |
- Bauer, Michael, et al.
(author)
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Association between solar insolation and a history of suicide attempts in bipolar I disorder.
- 2019
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In: Journal of psychiatric research. - : Elsevier BV. - 1879-1379 .- 0022-3956. ; 113, s. 1-9
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Journal article (peer-reviewed)abstract
- In many international studies, rates of completed suicide and suicide attempts have a seasonal pattern that peaks in spring or summer. This exploratory study investigated the association between solar insolation and a history of suicide attempt in patients with bipolar I disorder. Solar insolation is the amount of electromagnetic energy from the Sun striking a surface area on Earth. Data were collected previously from 5536 patients with bipolar I disorder at 50 collection sites in 32 countries at a wide range of latitudes in both hemispheres. Suicide related data were available for 3365 patients from 310 onset locations in 51 countries. 1047 (31.1%) had a history of suicide attempt. There was a significant inverse association between a history of suicide attempt and the ratio of mean winter solar insolation/mean summer solar insolation. This ratio is smallest near the poles where the winter insolation is very small compared to the summer insolation. This ratio is largest near the equator where there is relatively little variation in the insolation over the year. Other variables in the model that were positively associated with suicide attempt were being female, a history of alcohol or substance abuse, and being in a younger birth cohort. Living in a country with a state-sponsored religion decreased the association. (All estimated coefficients p<0.01). In summary, living in locations with large changes in solar insolation between winter and summer may be associated with increased suicide attempts in patients with bipolar disorder. Further investigation of the impacts of solar insolation on the course of bipolar disorder is needed.
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| 3. |
- Brodén, Karin, 1963-, et al.
(author)
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Determining Value in Welfare-Technology : The Need for a Multi-Perspective Framework
- 2023
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In: International Journal of Health Economics and Policy. - : Science Publishing Group. - 2578-9295 .- 2578-9309. ; 8:4, s. 76-88
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Journal article (peer-reviewed)abstract
- Background: Stakeholders in health and social care are implementing digital solutions to facilitate person-centred care for citizens. One problem is choosing which digital solution to implement. Ordinary cost-benefit analysis implicates the measurable parts of the value, leaving the immeasurable without any trace in an analysis. Results: We used design thinking to design a framework that implicates what to add as valuable factors on individual, organisational, and governmental levels. The design is based on empirical material from workshops and literature reviews on systems thinking, quality management, and value factors. The valuable factors at an individual level could include independence, autonomy, and empowerment, and the factors at the organisational level accessibility, competence, and independence. On a central level, the factors are related to person-centred care and its value proposals, such as autonomy and independence. Conclusions: While conducting a cost-benefit analysis, focusing on a standard definition of the value concept is essential. The designed framework needs to be dynamic due to the broad range of welfare technology. The created rubrics cube model, including strategic, organisational-operational and individual levels, should be used by decision-making groups as a flexible foundation. Forthcoming research will test this framework, including the proposed scale for measurement and focusing on welfare technology for older citizens.
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| 6. |
- Skov, Karin, et al.
(author)
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Det nordiske nyreudvekslingsprogram
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In: Ugeskrift for Læger. - 1603-6824 .- 0041-5782. ; , s. 1-6
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Journal article (peer-reviewed)abstract
- This review describes the ScandiaTransplant Kidney Exchange Programme and the background of renal exchange programmes gaining popularity worldwide, possibilities and limitations of the programmes, the ethical aspects and perspectives. The first kidney exchanges between Danish and Swedish countries were performed in 2019, and until now 23 exchanges and transplantations have been performed. All surgical procedures have been performed simultaneously and/or coordinated at different hospitals in Scandinavia, and the kidney grafts were transported between the participating units
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| 7. |
- Sørensen, Danny Mollerup, et al.
(author)
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The P5A ATPase Spf1p is stimulated by phosphatidylinositol 4-phosphate and influences cellular sterol homeostasis
- 2019
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In: Molecular Biology of the Cell. - : American Society for Cell Biology. - 1059-1524 .- 1939-4586. ; 30:9, s. 1069-1084
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Journal article (peer-reviewed)abstract
- P5A ATPases are expressed in the endoplasmic reticulum (ER) of all eukaryotic cells, and their disruption results in severe ER stress. However, the function of these ubiquitous membrane proteins, which belong to the P-type ATPase superfamily, is unknown. We purified a functional tagged version of the Saccharomyces cerevisiae P5A ATPase Spf1p and observed that the ATP hydrolytic activity of the protein is stimulated by phosphatidylinositol 4-phosphate (PI4P). Furthermore, SPF1 exhibited negative genetic interactions with SAC1, encoding a PI4P phosphatase, and with OSH1 to OSH6, encoding Osh proteins, which, when energized by a PI4P gradient, drive export of sterols and lipids from the ER. Deletion of SPF1 resulted in increased sensitivity to inhibitors of sterol production, a marked change in the ergosterol/lanosterol ratio, accumulation of sterols in the plasma membrane, and cytosolic accumulation of lipid bodies. We propose that Spf1p maintains cellular sterol homeostasis by influencing the PI4P-induced and Osh-mediated export of sterols from the ER.
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| 8. |
- Vandkilde, Helle, et al.
(author)
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Cultural Mobility in Bronze Age Europe
- 2015
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In: Forging Identities. The Mobility of Culture in Bronze Age Europe: Volume 1, Edited by Paulina Suchowska-Ducke, Samantha Scott Reiter, Helle Vandkilde. - Oxford : British Archaeological Reports. - 0143-3067. - 9781407314334 ; , s. 5-37
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Book chapter (peer-reviewed)abstract
- The purpose of the following introduction is threefold. First, it sets out to provide an outline of archaeological research into cultural mobility while highlighting the Bronze Age as a major epoch of connectivity in European prehistory. This will serve as the background for the second section, which summarises the main research incentives driving the investigation of mobility in the EC research and training programme Forging Identities – The Mobility of Culture in Bronze Age Europe (FI)1
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