Mém. de maîtrise--Histoire de l'art--Paris 4, 2002. / Bibliogr. p. 173.

This thesis evaluates expenditures made by Camp Henry patrons during the 2005 summer camp season while traveling to and from the residential camp located in Newaygo County, Michigan. A purposive random cluster sample was collected via self-administered questionnaire on the arrival days of weeks 3, 7, and 8 of the 8 week summer camp season. The data revealed expenditures in each of the categories on the instrument; lodging expenses, food and beverages, private auto expenses, retail shopping, recreation activities, and “other”. Expenditures for the 55 participants and the individuals traveling with them totaled $4,558. The category with the greatest reported expenditures was food and beverage, totaling $1,645 and the category with the least reported expenditures was lodging, totaling $170. First summer camper group expenditures and returning camper group expenditures were evaluated to determine if a relationship exists between inexperienced and experienced campers, a one-factor ANOVA was run with the logarithm of total expenditures and, with a P value of 0.077, no statistically significant relationship is found. A one-factor ANOVA was utilized to evaluate the relationship between participants residing within 35 miles of the residential camp facility and those living further away. With a P value of 0.101, it is determined that hometown does not have an effect on patron expenditures. A regression analysis of the logarithm of total expenditures and income ranges was performed to determine if an individual’s annual income has an effect on expenditures; with a P value of 0.626 no relationship was found. Lastly, a regression analysis of the logarithm of total expenditures and participant age was run to determine if a relationship between a participant’s age and the amount spent exists. With a P value of 0.574, no statistically significant relationship exists. Limitations of the study include a small sample size, the inability of participants to accurately predict return trip expenditures, and the close proximity of participant residences to the camp facility. Although no statistically significant relationships were found, the expenditure information can be used to develop partnerships between local businesses and the residential summer camp. The possibility of exploring the camp going population and their monetary value to host communities is a worthwhile subject for further scrutiny. The information presented here can be used as a starting point for future studies on expenditures of residential camp patrons.

Formulación espectral de la radiación en coordenadas cartesianas, cilíndricas y esféricas. Aplicación de la formulación a problemas de diagnostico de antenas, análisis del efecto de radomos y transformación campo próximo campo lejano.Estudio del efecto de errores de medida en campo próximo cilíndrico sobre el diagrama de radiación. Se aplican los desarrollos realizados al diseño, construcción y validación de un campo próximo de medida de antenas en coordenadas cilíndricas. / A unified approach of radiation of sources (antennas) in Cartesian, cylindrical and spherical coordinates is presented. The relationship between model expansions is developed and major characteristics of each modal expansion are discussed.The formulation is applied to the near to far field transformation in cylindrical coordinates and design expressions for the implementation of a cylindrical near-field range are developed. These design expressions allow to specify the measuring system in terms of positioning errors and required signal to noise ratio to achieve a certain degree of accuracy in the far field radiation pattern.Finally, a practical design of a cylindrical near field range operating in S band is presented.

Thesis (M.A.)--Universität Bonn, 2008. / Includes bibliographical references (p. 103-110).

No description available.

Cyclic-3',5 '-adenosine monophosphate (cAMP) is an ancient signaling molecule that is found in a variety of species from prokaryotes to eukaryotes and translates extra-cellular stimuli into tightly controlled intra-cellular responses. The two major mammalian cAMP sensors are protein kinase A (PKA), for the phosphorylation of the downstream effectors, and the exchange protein directly activated by cAMP (Epac ), for the guanine nucleotide exchange in the small GTPase Rap proteins. In this study, we investigated the intra-molecular cAMP dependent allosteric network of Epac cyclic nucleotide binding domain (CBD) via solution NMR spectroscopy. Epac proteins have been shown to employ an auto-inhibition strategy in the control of the equilibrium between the active and the inactive states. In the absence of cAMP, the periphery of the Rap recognition site is masked via an ionic interface provided by the N-terminus of the CBD. Binding of cAMP at the distal Phosphate Binding Cassette (PBC), results in weakening of this interface. Here we show that the cAMP binding signal is propagated to the sites important in Epac activation, i.e. the ionic interface, via two key allosteric spots within the CBD. We have also determined the dynamics as a key carrier of cAMP effects to the region forming the ionic interface (ionic latch). Hence entropic enhancements emerged as a key effector in the cAMP mediated ionic latch weakening. We have also provided initial evidence of a negative allosteric contribution from the C-terminal Hinge-Lid region (CHLR) on the cAMP induced Epac activation. In addition to these findings, we also observed critical differences in the mode of cAMP recognition and inter-subdomain communication between the Epac and PKA. A detailed understanding of these two ubiquitous systems, will aid in the development of agonists and antagonists that are relevant in the drug lead development for related diseases, such as Alzheimer's and diabetes. / Thesis / Master of Science (MSc)

No description available.

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.

It is known that guidance cues play important roles in neuronal outgrowth and axonal path-finding. These guidance cues, when bound to the receptors on nerve growth cones, trigger a series of signal transduction pathways that result in dynamic rearrangement of cytoskeleton in neuronal cells. Although enormous studies have been suggested that intracellular calcium concentration is crucial in regulation of neurite outgrowth and cytoskeleton rearrangement, the precise molecular mechanism underlying growth cone guidance is not well understood. The aim of our studies is to set up an evaluation system, growth cone turning assay, which is suitable and reproducible for exploration of the molecular mechanism of guidance cue-induced growth cone turning. The 1-day-old cultured spinal neurons of Xenopus laevis and the approved attractive guidance cue, cAMP, were used in our growth cone turning assay. We evaluate the effects of neuronal developmental stage, size of pressure, frequency and duration in cAMP-induced growth cone turning. We found application of cAMP with a pressure of 2 Hz in frequency and 20 ms in duration can elicit a reliable growth cone attractive response in cultured spinal motoneurons with 14~18 hours in age. Depletion of intracellular calcium store with thapsigargin in calcium-free Ringer could significantly abolish cAMP-induced growth cone turning. The cAMP-induced growth cone turning was not blunted when calcium was omitted from extracellular fluid or bath application of calcium channel inhibitor suggesting calcium influx is not responsible for the growth cone attractive effect of cAMP. Application of membrane-permeable inhibitors of ryanodine receptors but not inositol 1,4,5-trisphosphate (IP3) effectively occluded the attractive effect elicited by cAMP. The cAMP-induced growth cone turning was unapparent under the presence of Li+, a blocker of IP3 formation. It has been suggest besides block IP3 formation, Li+ is also involved in modulation of several signaling pathways including GSK3-£] dependent signaling. However, bath application of GSK3-£] inhibitor has no significant effect on cAMP-induced growth cone turning. Taken together, our results suggest ryanodine-mobilized intracellular Ca2+ store play a major role in cAMP-induced growth cone turning. Moreover, our result on surveying various embryonic stage, drug application protocol also establish a good condition for neuronal growth cone turning assay, which can be used in exploring the molecular mechanism of growth cone path-finding.