Thesis (Ph. D.)--Oregon Graduate Center, 1977.

The main objective of this work is to propose new procedures for the general dynamic factor analysis introduced by Forni et al. (2000). First, we develop an identification method for determining the number of common shocks in the general dynamic factor model. Sufficient conditions for consistency of the criterion are provided for large n (number of series) and T (the series length). We believe that our procedure can shed light on the ongoing debate on the number of factors driving the US or Eurozone economy. Second, we show how the dynamic factor analysis method proposed in Forni et al. (2000), combined with our identification method, allows for identifying and estimating joint and block-specific common factors. This leads to a more sophisticated analysis of the structures of dynamic interrelations within and between the blocks in suchdatasets. Besides the framework of the general dynamic factor model we also propose a consistent lag window spectral density estimator based on multivariate M-estimators by Maronna (1976) when the underlying data are coming from the alpha mixing stationary Gaussian process.

Risk neutral strategies emphasize stock selection rather than market timing in order to achieve the objective of a positive abnormal return. Using CAPM and Fama-French three-factor models as benchmark, this study applies the risk neutral strategies to Taiwanese stock markets. Empirical results reveal that R-square of Fama-French 3-factor model is higher than that of CAPM, implying that Fama-French model outperforms CAPM in explaining the stock returns in our sample. In addition, Portfolios 1 and 2 generate significantly positive abnormal returns. We conclude that risk neutral strategies offer positive abnormal returns.

The work described in this thesis deals with two pore forming toxins, namely Arcanobacterium pyogenes pyolysin and Streptococcus agalactiae CAMP factor. Pyolysin (PLO) belongs to the homologous group of cholesterol-dependent cytolysins. In chapter 2, it is shown that PLO can form small oligomers in solution, without the requirement for any membranes or membrane lipids. These small oligomers may aggregate into larger ones on membranes; however, in solution, they apparently do not grow by addition of further monomers, as their size is virtually unaffected by variations of incubation time or toxin concentration. The small, solution-derived oligomers retain hemolytic activity. The membrane lesions observed by electron microscopy are similar to those that are formed by monomeric PLO, except that they are mostly incomplete and arc-shaped, as opposed to the predominantly ring-shaped ones formed by monomeric PLO when directly incubated with membranes. This structural difference corresponds to a detectable difference in functional pore size, as determined by marker release experiments. Thus, arc-shaped PLO oligomers may form functional pores of reduced size. In chapter 3, we show that liposomes that contain phosphatidylcholine and ceramide but no cholesterol or other sterol are susceptible to the cholesterol-dependent cytolysin pyolysin. Pyolysin, at a low rate, forms small oligomers in solution. The solution-derived oligomers are more effective on ceramide-containing liposomes than the monomeric toxin. In contrast, they have much lower activity on liposome membranes that contain cholesterol but no ceramide. Our findings therefore show that at least one member of the ‘cholesterol-dependent cytolysins’ is in fact not strictly dependent on the sterol. In addition, in conjunction with previous data, they suggest that the requirement for cholesterol involves early or intermediate stages of oligomer formation, rather than the final event of membrane insertion. Chapter 4 of this thesis concerns Streptococcus agalactiae CAMP factor. CAMP factor has previously been reported to bind the Fc fragments of immunoglobulin G (IgG) and has therefore also been called ‘protein B’, in analogy to protein A of Staphylococcus aureus. We attempted to characterize the interaction of protein B with IgG in more detail. In contrast to protein A, CAMP factor does not inhibit the activation of complement by hemolysin antibodies bound to sheep red cell surfaces. IgG also failed to inhibit the cohemolytic activity of CAMP factor, which it displays on sphingomyelinase-treated sheep red cells; this is in disagreement with previous findings. After co-incubation, CAMP factor and IgG were cleanly separated by gel filtration. Therefore, CAMP factor does not detectably bind to IgG.

The work described in this thesis deals with two pore forming toxins, namely Arcanobacterium pyogenes pyolysin and Streptococcus agalactiae CAMP factor. Pyolysin (PLO) belongs to the homologous group of cholesterol-dependent cytolysins. In chapter 2, it is shown that PLO can form small oligomers in solution, without the requirement for any membranes or membrane lipids. These small oligomers may aggregate into larger ones on membranes; however, in solution, they apparently do not grow by addition of further monomers, as their size is virtually unaffected by variations of incubation time or toxin concentration. The small, solution-derived oligomers retain hemolytic activity. The membrane lesions observed by electron microscopy are similar to those that are formed by monomeric PLO, except that they are mostly incomplete and arc-shaped, as opposed to the predominantly ring-shaped ones formed by monomeric PLO when directly incubated with membranes. This structural difference corresponds to a detectable difference in functional pore size, as determined by marker release experiments. Thus, arc-shaped PLO oligomers may form functional pores of reduced size. In chapter 3, we show that liposomes that contain phosphatidylcholine and ceramide but no cholesterol or other sterol are susceptible to the cholesterol-dependent cytolysin pyolysin. Pyolysin, at a low rate, forms small oligomers in solution. The solution-derived oligomers are more effective on ceramide-containing liposomes than the monomeric toxin. In contrast, they have much lower activity on liposome membranes that contain cholesterol but no ceramide. Our findings therefore show that at least one member of the ‘cholesterol-dependent cytolysins’ is in fact not strictly dependent on the sterol. In addition, in conjunction with previous data, they suggest that the requirement for cholesterol involves early or intermediate stages of oligomer formation, rather than the final event of membrane insertion. Chapter 4 of this thesis concerns Streptococcus agalactiae CAMP factor. CAMP factor has previously been reported to bind the Fc fragments of immunoglobulin G (IgG) and has therefore also been called ‘protein B’, in analogy to protein A of Staphylococcus aureus. We attempted to characterize the interaction of protein B with IgG in more detail. In contrast to protein A, CAMP factor does not inhibit the activation of complement by hemolysin antibodies bound to sheep red cell surfaces. IgG also failed to inhibit the cohemolytic activity of CAMP factor, which it displays on sphingomyelinase-treated sheep red cells; this is in disagreement with previous findings. After co-incubation, CAMP factor and IgG were cleanly separated by gel filtration. Therefore, CAMP factor does not detectably bind to IgG.

Human enteric pathogen Salmonella contaminates raw produce and triggers significant economic loss and illness. Under a natural environment, Salmonella resides in soil and enters the interior of plants without causing disease or eliciting symbiotic growth. Upon being consumed by humans, complex virulence mechanisms are elicited by the specific intestine conditions, such as high temperature and humidity and lead to profound infection. The lack of effective prevention and drug treatment are largely attributed to the unclear mechanistic understanding on Salmonella association with environmental media, and in vivo host and pathogen factors required for persistent infection. We have explored the potential of deploying the model plant organism Arabidopsis thaliana to tackle this fundamental yet clinically challenging question, as Arabidopsis possesses many advantages as a model system, including enriched genomic resources, powerful genetic tools, low maintenance cost and a large collection of individual gene deletion mutants. Our preliminary data demonstrated Arabidopsis seedlings under liquid culture conditions mimicking the intestine environment were infected and killed by salmonella within 2 days upon inoculation. The Arabidopsis system possesses well-developed genetic information and the resources to study host factors required for infection on very short time scales, thus complementing traditional animal genetic studies. We aim to define the pathogen factors required for this infection. By merging the fields of extremely powerful Arabidopsis genetics and bacterial genetics/genomics, we hope to provide insight into possible new paradigms for addressing salmonella-mediated food born infection.

We first identified the transcriptional regulatory element of the human dynamin IV gene (Hdyn IV; dymple). The Hdyn IV belongs to a large GTPase family. This protein has a N-terminal highly conserved tripartite GTP-binding domain, coiled-coil (CC) region, but it lacks the pleckstrin homology (PH) domain and a modestly conserved C-terminal proline rich domain (PRD). Hdyn IV gene is enriched in subcellular membrane fractions of cytoplasmic vesicles and endoplasmic reticulum, and the function of Hdyn IV gene is considered to be associated with the functions of mitochondria. The Hdyn IV is expressed as four alternative splicing variants in all eukaryotic organisms. Our question concerning why expressions of four alternative splicing variants in brain tumor tissues? To elucidate the regulatory mechanism and the transcription factors involved, we firstly determined the transcriptional start site by 5¡¦ RACE. We next cloned the 5¡¦-flanking region of the Hdyn IV gene and determined the nucleotide sequence of 999 bases upstream from the transcription start site. The promoter has several potential binding sites for AP2, Sp1 binding protein, but it lacks TATA and CAAT boxes. Transfection studies using a series of Hdyn IV promoter luciferase constructs in HeLa cell demonstrate that the 5¡¦flanking region has a promoter activity. Functional promoter element of the Hdyn IV gene was located within the ¡V140~ +29 region. Deletion analyses demonstrated that the minimal promoter activity for the transcriptional element of Hdyn IV was detected in the sequence between nucleotides ¡V110 and ¡V100. Electorphoretic mobility shift assay demonstrated that a putative transcriptional factor bound to the ¡V119 to ¡V90 region. Site-directed mutagenesis analysis of this region revealed that nucleotides at positions ¡V108 to ¡V100 were essential for transactivation mediated by this element. To summary, the data indicated that the ¡¦¡¦CTCCCAGCA¡¦¡¦ (-108~ -100) sequence is capable of regulating Hdyn IV gene expression. However, the protein involved in the binding of this novel sequence requires further study.

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As deregulation of the electric power system in the United States unfolds, many customers are experiencing changes in their billing rate structure. Some face the addition of power factor penalty tariffs, and seek ways to minimize the added burden. The installation of entrance capacitor banks is the common response, but fails to take complete advantage of capacitor abilities. Other project designs exist that can harness these advantages to the full benefit of the customer. This work will show that distributing shunt capacitors in parallel with induction motors will elevate power factor and voltage, and also decrease ohmic losses in the wiring and protection devices that supply the motor. This reduction often produces a better overall economic solution due to energy savings. The distribution of capacitors at induction motors reduces the reactive current in the branch of the distribution system that supplies them. A reduction in the total current flowing to the motor along the distribution system results in smaller losses throughout the system. As losses diminish, the total real power drawn through the distribution system is lessened, and electric bills are reduced. This alternative to entrance capacitor banks is not as commonly implemented. A misconception that the resistance in facility distribution systems is relatively low has discouraged distributed motor capacitor installation for overall facility power factor correction, in favor of entrance capacitor banks. We will show that the resistance in the distribution system is higher than typically thought, that motor capacitors can exploit this fact, and can often economically outperform entrance capacitor banks which are terminated at the point of incoming utility power. Motor capacitors are not a new technology. They are commercially available off the shelf technology, suitable for power factor correction for induction motors. Distributed capacitors can be utilized for all significantly sized induction motors in a facility. The elevation in power factor and voltage, reduction in reactive current and real power are calculated, and trends are observed. The matter is considered from both the standpoint of engineering and economics to provide an integrated study.

Akademisk avhandling--Göteborgs högskola. / Extra t.p., with thesis note, inserted. "Literatureförteckning": p. [264]-281.