# Sökning: "johan richter"

1. ## 1. Algebraic Properties of Ore Extensions and Their Commutative Subrings

Sammanfattning : This thesis deals with a class of rings known as Ore extensions. An Ore extension can be described as a noncommutative ring of polynomials in one variable. A special focus of the thesis is the study of commuting elements in Ore extensions. LÄS MER

2. ## 2. Fluorescence Guided Resection of Brain Tumors Evaluation of a Hand-held Spectroscopic Probe

Sammanfattning : Malignant gliomas grow infiltrative in the brain and can therefore not be completely removed by neurosurgical means. However, for an optimized oncological treatment it has proven useful to resect as much as possible of tumor. The identification of the tumor in the marginal zone is difficult but crucial. LÄS MER

3. ## 3. Reordering in Noncommutative Algebras, Orthogonal Polynomials and Operators

Sammanfattning : The main object studied in this thesis is the multi-parametric family of unital associative complex algebras generated by the element $Q$ and the finite or infinite set $\{S_j\}_{j\in J}$ of elements satisfying the commutation relations $S_jQ=\sigma_j(Q)S_j$, where $\sigma_j$ is a polynomial for all $j\in J$. A concrete representation is given by the operators $Q_x(f)(x)=xf(x)$ and $\alpha_{\sigma_j}(f)(x)=f(\sigma_j(x))$ acting on polynomials or other suitable functions. LÄS MER