On the Structure of Covers of Sofic Shifts

A canonical cover generalizing the left Fischer cover to arbitrary sofic shifts is introduced and used to prove that the left Krieger cover and the past set cover of a sofic shift can be divided into natural layers. These results are used to find the range of a flow-invariant and to investigate the ideal structure of the universal C*-algebra associated to a sofic shift space.Comment: To appear in Documenta Mathematica. Section 2 has been shortened. Three sections concerning the layered structure of the left Krieger cover and the past set cover have been merged and rewritten. Non-essential examples have been omitted. 21 pages, 8 figure

The Cuntz splice does not preserve ∗*-isomorphism of Leavitt path algebras over Z\mathbb{Z}

We show that the Leavitt path algebras $L_{2,\mathbb{Z}}$ and $L_{2-,\mathbb{Z}}$ are not isomorphic as $*$-algebras. There are two key ingredients in the proof. One is a partial algebraic translation of Matsumoto and Matui's result on diagonal preserving isomorphisms of Cuntz--Krieger algebras. The other is a complete description of the projections in $L_{\mathbb{Z}}(E)$ for $E$ a finite graph. This description is based on a generalization, due to Chris Smith, of the description of the unitaries in $L_{2,\mathbb{Z}}$ given by Brownlowe and the second named author. The techniques generalize to a slightly larger class of rings than just $\mathbb{Z}$.Comment: 17 pages. Since version 2 we extended the arguments from Z to more general ring

On Flow Equivalence of Sofic Shifts

The flow equivalence of sofic shifts is examined using results about the structure of the corresponding covers. A canonical cover generalising the left Fischer cover to arbitrary sofic shifts is introduced and used to prove that the left Krieger cover and the past set cover of a sofic shift can be divided into natural layers. These results are used to find the range of a flow invariant and to investigate the ideal structure of the universal C^*-algebras associated to sofic shifts. The right Fischer covers of sofic beta-shifts are constructed, and it is proved that the covering maps are always 2 to 1. This is used to construct the corresponding fiber product covers and to classify these up to flow equivalence. Additionally, the flow equivalence of renewal systems is studied, and several partial results are obtained in an attempt to find the range of the Bowen-Franks invariant over the set of renewal systems of finite type. In particular, it is shown that the Bowen-Franks group is cyclic for every member of a class of renewal systems known to attain all entropies realised by shifts of finite type.Comment: 143 pages, 36 figures, PhD thesi

Validation of miRNA genes suitable as Reference genes in qPCR analyses of miRNA gene expression in Atlantic salmon (Salmo salar)

Background MicroRNAs (miRNAs) are an abundant class of endogenous small RNA molecules that downregulate gene expression at the post-transcriptional level. They play important roles by regulating genes that control multiple biological processes, and recent years there has been an increased interest in studying miRNA genes and miRNA gene expression. The most common method applied to study gene expression of single genes is quantitative PCR (qPCR). However, before expression of mature miRNAs can be studied robust qPCR methods (miRNA-qPCR) must be developed. This includes identification and validation of suitable reference genes. We are particularly interested in Atlantic salmon (Salmo salar). This is an economically important aquaculture species, but no reference genes dedicated for use in miRNA-qPCR methods has been validated for this species. Our aim was, therefore, to identify suitable reference genes for miRNA-qPCR methods in Salmo salar. Results We used a systematic approach where we utilized similar studies in other species, some biological criteria, results from deep sequencing of small RNAs and, finally, experimental validation of candidate reference genes by qPCR to identify the most suitable reference genes. Ssa-miR-25-3p was identified as most suitable single reference gene. The best combinations of two reference genes were ssa-miR-25-3p and ssa-miR-455-5p. These two genes were constitutively and stably expressed across many different tissues. Furthermore, infectious salmon anaemia did not seem to affect their expression levels. These genes were amplified with high specificity, good efficiency and the qPCR assays showed a good linearity when applying a simple cybergreen miRNA-PCR method using miRNA gene specific forward primers. Conclusions We have identified suitable reference genes for miRNA-qPCR in Atlantic salmon. These results will greatly facilitate further studies on miRNA genes in this species. The reference genes identified are conserved genes that are identical in their mature sequence in many aquaculture species. Therefore, they may also be suitable as reference genes in other teleosts. Finally, the systematic approach used in our study successfully identified suitable reference genes, suggesting that this may be a useful strategy to apply in similar validation studies in other aquaculture species

Shared Mental Models: National Representative Coaches’ Thinking on Importance, Characteristics, and Development

The aims of the study were to explore how national representative handball coaches reflect on the cognitive properties of the team and how these attributes are developed through team practice. A theoretical (shared mental models) thematic analysis was conducted, and five coaches with extensive experience from the national team and elite clubs participated. The data were analyzed with regard to three overarching topics: importance, characteristics, and development of shared mental models. The interviews revealed that measures intended to influence a shared mental model permeate team practice and underpin the assumption of opponent-specific shared mental models. Alignment between briefings and debriefings as well as field practice were emphasized and used to enhance a shared mental model and understood as measures that facilitate pattern recognition and primed decisions. Single-loop as well as double-loop learning were identified as coaching initiatives to promote the development of shared mental models. Systematic practice with the goal of promoting coordination through repetition of the coordinative patterns in critical game situations was emphasized. Implicit communication is a characteristic of teams sharing a mental model, and distinct proactive bodily movements were emphasized as a crucial requirement for coordination. A model was elaborated to show how the categories can be understood in the cyclic relation between matches and the development of shared mental models.publishedVersio

Shared Mental Models: National Representative Coaches’ Thinking on Importance, Characteristics, and Development

The aims of the study were to explore how national representative handball coaches reflect on the cognitive properties of the team and how these attributes are developed through team practice. A theoretical (shared mental models) thematic analysis was conducted, and five coaches with extensive experience from the national team and elite clubs participated. The data were analyzed with regard to three overarching topics: importance, characteristics, and development of shared mental models. The interviews revealed that measures intended to influence a shared mental model permeate team practice and underpin the assumption of opponent-specific shared mental models. Alignment between briefings and debriefings as well as field practice were emphasized and used to enhance a shared mental model and understood as measures that facilitate pattern recognition and primed decisions. Single-loop as well as double-loop learning were identified as coaching initiatives to promote the development of shared mental models. Systematic practice with the goal of promoting coordination through repetition of the coordinative patterns in critical game situations was emphasized. Implicit communication is a characteristic of teams sharing a mental model, and distinct proactive bodily movements were emphasized as a crucial requirement for coordination. A model was elaborated to show how the categories can be understood in the cyclic relation between matches and the development of shared mental models.publishedVersio