If X is a locally compact Hausdorff space, then a representation of the complex C* algebra C_0(X) on a Hilbert space $H$ is given by a spectral measure that takes its values in the orthogonal... Show moreIf X is a locally compact Hausdorff space, then a representation of the complex C* algebra C_0(X) on a Hilbert space $H$ is given by a spectral measure that takes its values in the orthogonal projections on $H$. It is natural to ask whether something similar is true for a positive representation of the ordered Banach algebra C_0(X) on a Banach lattice E. If E is a KB-space or if E is reflexive, then the answer is affirmative: the representation is given by a spectral measure that takes its values in the positive projections on X. The proofs of above results make use of the fact that E is a Banach space, but there should be a purely order-theoretic approach. In chapter 1 of this thesis, we shall explain that this is indeed the case. In chpater 2, we are talking about simultaneous power factorization in Banach algebras. In an ordered context, we also consider the existence of a positive factorization for a subset of the positive cone of an ordered Banach space that is a positive module over an ordered Banach algebra with a positive bounded left approximate identity. Show less
The topics in this thesis revolve around a group of plus-strand RNA viruses that belong to the Flavivirus genus, a general introduction of which is presented in Chapter 1. The experimental chapters... Show moreThe topics in this thesis revolve around a group of plus-strand RNA viruses that belong to the Flavivirus genus, a general introduction of which is presented in Chapter 1. The experimental chapters in this thesis mainly focus on the construction and characterization of flavivirus infectious clones and the application of these useful tools to address fundamental questions on virus biology or to explore novel vaccine platforms based on the yellow fever virus vaccine strain (YFV-17D). Chapter 2 describes the construction and characterization of recombinant YFV-17D viruses expressing Lassa virus (LASV) glycoprotein coding sequences as bivalent vaccine candidates against wildtype YFV and LASV that circulate in the same region in West Africa. Chapter 3 describes the construction and characterization of an alternative YFV-17D vaccine candidate based on a DNA launched YFV-17D infectious clone, and the study of its immunological characteristics. Chapter 4 describes the construction and characterization of the first NKV (no known vector) flavivirus infectious clone, which was further utilized to study the functional significance of RNA elements present in Modoc virus (MODV) 3__-UTR (untranslated region), as a representative of the NKV flaviviruses. A recently discovered common feature for all flaviviruses is the production of a small flavivirus RNA (sfRNA) in infected cells or animals that results from the incomplete degradation of the viral genome by the host exoribonuclease, XRN-1. XRN-1 was predicted to be stalled by a non-H-type RNA pseudoknot structure that is present is the 3__-UTR of every flavivirus studied thus far. Chapter 5 presents a detailed mutagenesis study of many of the unique sequence and structural characteristics of the XRN-1 stalling site in mosquito-borne flaviviruses using YFV-17D as a model. Chapter 6 describes the establishment of mammalian cell lines that constitutively expressed sfRNA from YFV-17D and WNV. This cell line approach could be valuable to further our understanding of sfRNA function within flavivirus life cycle. Chapter 7 of this thesis is a short epilogue, in which the findings presented in the experimental chapters are summarized and discussed in the context of recently published findings and future research directions are suggested to improve the YFV-17D based vaccine platforms or to address the yet-to-be-solved questions about sfRNA production and function. Show less
