Building generic anatomical models using virtual model cutting and iterative registration

Article deposited according to publisher policy posted on SHERPA/RoMEO, 30/07/2010.YesFunding provided by the Open Access Authors Fund

Comparative study of unsupervised dimension reduction techniques for the visualization of microarray gene expression data

<p>Abstract</p> <p>Background</p> <p>Visualization of DNA microarray data in two or three dimensional spaces is an important exploratory analysis step in order to detect quality issues or to generate new hypotheses. Principal Component Analysis (PCA) is a widely used linear method to define the mapping between the high-dimensional data and its low-dimensional representation. During the last decade, many new nonlinear methods for dimension reduction have been proposed, but it is still unclear how well these methods capture the underlying structure of microarray gene expression data. In this study, we assessed the performance of the PCA approach and of six nonlinear dimension reduction methods, namely Kernel PCA, Locally Linear Embedding, Isomap, Diffusion Maps, Laplacian Eigenmaps and Maximum Variance Unfolding, in terms of visualization of microarray data.</p> <p>Results</p> <p>A systematic benchmark, consisting of Support Vector Machine classification, cluster validation and noise evaluations was applied to ten microarray and several simulated datasets. Significant differences between PCA and most of the nonlinear methods were observed in two and three dimensional target spaces. With an increasing number of dimensions and an increasing number of differentially expressed genes, all methods showed similar performance. PCA and Diffusion Maps responded less sensitive to noise than the other nonlinear methods.</p> <p>Conclusions</p> <p>Locally Linear Embedding and Isomap showed a superior performance on all datasets. In very low-dimensional representations and with few differentially expressed genes, these two methods preserve more of the underlying structure of the data than PCA, and thus are favorable alternatives for the visualization of microarray data.</p

Genetic Determinants of Cardiovascular Events among Women with Migraine: A Genome-Wide Association Study

Migraine is associated with an increased risk for cardiovascular disease (CVD). Both migraine and CVD are highly heritable. However, the genetic liability for CVD among migraineurs is unclear.We performed a genome-wide association study for incident CVD events during 12 years of follow-up among 5,122 migraineurs participating in the population-based Women's Genome Health Study. Migraine was self-reported and CVD events were confirmed after medical records review. We calculated odds ratios (OR) and 95% confidence intervals (CI) and considered a genome-wide p-value <5×10(-8) as significant.Among the 5,122 women with migraine 164 incident CVD events occurred during follow-up. No SNP was associated with major CVD, ischemic stroke, myocardial infarction, or CVD death at the genome-wide level; however, five SNPs showed association with p<5×10(-6). Among migraineurs with aura rs7698623 in MEPE (OR = 6.37; 95% CI 3.15-12.90; p = 2.7×10(-7)) and rs4975709 in IRX4 (OR = 5.06; 95% CI 2.66-9.62; p = 7.7×10(-7)) appeared to be associated with ischemic stroke, rs2143678 located close to MDF1 with major CVD (OR = 3.05; 95% CI 1.98-4.69; p = 4.3×10(-7)), and the intergenic rs1406961 with CVD death (OR = 12.33; 95% CI 4.62-32.87; p = 5.2×10(-7)). Further, rs1047964 in BACE1 appeared to be associated with CVD death among women with any migraine (OR = 4.67; 95% CI 2.53-8.62; p = 8.0×10(-7)).Our results provide some suggestion for an association of five SNPs with CVD events among women with migraine; none of the results was genome-wide significant. Four associations appeared among migraineurs with aura, two of those with ischemic stroke. Although our population is among the largest with migraine and incident CVD information, these results must be treated with caution, given the limited number of CVD events among women with migraine and the low minor allele frequencies for three of the SNPs. Our results await independent replication and should be considered hypothesis generating for future research

Landschaftsarchitektur und Architektur : Reflexionen, Einordnungen und Perspektiven der Wechselwirkung zweier Professionen

At the turn of the 20th and 21st century far-reaching changes in urban and rural regions imply a transformation in the performance requirements for the professions of landscape architecture and architecture. Simultaneous shrinking and growing of settlement structures, a diversification in the demands of users in regard to the living and working environment and the correlated economic, ecological and social complexity of planning tasks mean new challenges for the two disciplines: these problems cannot be solved isolated from each other, integrated and sustainable long term solutions are needed instead of superficial and one-dimensional approaches. The increasing correlation between building and open space systems implied in these tendencies necessitates a redetermination of the professions involved and their relationship to each other. Professional self-conceptions and perspectives of landscape architects and architects as well as the implied positions in practice manifest themselves in planned and realised 'products'. Aiming to achieve appropriate results and to draw adequate conclusions the multiplex spatial interaction between landscape architecture and architecture is analysed and categorised here based on representative projects. In this way a system of the diverse approaches and focal points of the design interplay between these two disciplines can be developed: spatial references and forming influences as well as the mutual integration of design elements, artificial citations and visual interconnections. The analysis of the relationship between landscape architecture and architecture and the according classification covers both the historical as well as the current contexts. Thereby different scales from single objects to spacious planning are taken into account. Additionally the positions and professional profiles of relevant protagonists are incorporated into the study. Thus complex and sometimes parallel processes can be correlated with each other and overall tendencies of professional development can be differentiated. This approach shows the multi-layered strands of profilation, expansion, hierarchisation and interdisciplinary cooperation. In the conclusion intersections in designing between landscape architecture and architecture – in consideration of separate competences – are summarised. This is followed by statements on the reciprocal positioning of the two professions in practice. Due to the high relevance for future developments a conceptual model for a study structure that takes account of the gained results is included. Thereby fields of professional overlapping and differentiation as well as individual focuses and specialisations are being shaped. Links to connecting points and questions for further research as well as a description of the implementation in teachings complete the work

Landschaftsarchitektur und Architektur : Reflexionen, Einordnungen und Perspektiven der Wechselwirkung zweier Professionen

At the turn of the 20th and 21st century far-reaching changes in urban and rural regions imply a transformation in the performance requirements for the professions of landscape architecture and architecture. Simultaneous shrinking and growing of settlement structures, a diversification in the demands of users in regard to the living and working environment and the correlated economic, ecological and social complexity of planning tasks mean new challenges for the two disciplines: these problems cannot be solved isolated from each other, integrated and sustainable long term solutions are needed instead of superficial and one-dimensional approaches. The increasing correlation between building and open space systems implied in these tendencies necessitates a redetermination of the professions involved and their relationship to each other. Professional self-conceptions and perspectives of landscape architects and architects as well as the implied positions in practice manifest themselves in planned and realised 'products'. Aiming to achieve appropriate results and to draw adequate conclusions the multiplex spatial interaction between landscape architecture and architecture is analysed and categorised here based on representative projects. In this way a system of the diverse approaches and focal points of the design interplay between these two disciplines can be developed: spatial references and forming influences as well as the mutual integration of design elements, artificial citations and visual interconnections. The analysis of the relationship between landscape architecture and architecture and the according classification covers both the historical as well as the current contexts. Thereby different scales from single objects to spacious planning are taken into account. Additionally the positions and professional profiles of relevant protagonists are incorporated into the study. Thus complex and sometimes parallel processes can be correlated with each other and overall tendencies of professional development can be differentiated. This approach shows the multi-layered strands of profilation, expansion, hierarchisation and interdisciplinary cooperation. In the conclusion intersections in designing between landscape architecture and architecture – in consideration of separate competences – are summarised. This is followed by statements on the reciprocal positioning of the two professions in practice. Due to the high relevance for future developments a conceptual model for a study structure that takes account of the gained results is included. Thereby fields of professional overlapping and differentiation as well as individual focuses and specialisations are being shaped. Links to connecting points and questions for further research as well as a description of the implementation in teachings complete the work

Do investments in human and physical capital respond differently to financing constraints?

Using a representative sample of European firms, we study whether financing constraints affect employers’ investments in employee training and physical capital differently. We measure financing constraints with an index that combines survey and balance sheet data. We instrument this index with the non-performing loans ratio of the bank that provided the last loan to the firms or with the average ratio of banks in the local area. We find that financing constraints have no effect on investment in training, but substantially reduce investment in physical capital