Exploring several nonconventional interactions of ice-binding proteins

Traditionally, ice-binding proteins (IBPs), also known as antifreeze proteins (AFPs), have been defined by two universal activities: ice recrystallization inhibition and thermal hysteresis. However, there remains the possibility IBPs have other complementary functions given the diversity found within this protein group. This thesis explores some of these in both natural and applied settings, in the hopes of furthering our understanding of this remarkable group of proteins. Plant IBPs could function as part of a defensive strategy against ice nucleators produced by certain pathogens. To assess this hypothesis, recombinant IBPs from perennial ryegrass and purple false brome were combined with the ice nucleation protein (INP) from the plant pathogen, Pseudomonas syringae. Strikingly, the plant proteins depressed the freezing point of the bacterial INP, while a fish AFP could not, nor did the INPs have any effect on IBP activity. Thus, the interaction between these two different proteins suggests a role in plant defensive strategies against pathogenic bacteria as another IBP function. In addition, the potential use of hyperactive insect IBPs in organ preservation was investigated. Current kidney preservation techniques involve storing the organ at 4 °C for a maximum of 24 h prior to transplantation. Extending this “safe” time would have profound effects on renal transplants, however, ischemic injury is prevalent when storage periods are prolonged. Experiments described here allowed subzero preservation for 72 h with the addition of a beetle IBP to CryoStasis® solution. Kidneys stored using the traditional technique for 24 h and the method developed here for 72 h showed similar levels of biomarker enzymes, underscoring the potential utility of insect IBPs for future transplant purposes. Finally, IBP function in the freeze-tolerant gall fly, Eurosta solidaginis, was examined. Larvae representing the mid-autumn stage displayed ice-binding activity, suggesting an IBP is being expressed, possibly as a protective measure against freezing damage when fall temperatures can unpredictably drop. IBP activity was also observed in the larvae’s host plant, Solidago spp. Mass spectrometry analysis of ice-affinity purified plant extracts provided three candidate pathogenesis-related proteins that could be responsible for the detected activity, further demonstrating additional functions of IBPs.

The Comparative Effectiveness of EEG Biomarkers in Antidepressant Response and Illness Prediction in Major Depressive Disorder

Thesis (Ph.D, Neuroscience Studies) -- Queen's University, 2016-08-27 00:55:35.782

An Islanding Detection Method based on Impedance Estimation and Grid Identification for Grid-Tie Distributed Power Generation Systems

Power system policies are broadly on track to escalate the use of renewable energy resources in electric power generation. Integration of dispersed generation to the utility network not only intensifies the benefits of renewable generation but also introduces further advantages such as power quality enhancement and freedom of power generation for the consumers. However, issues arise from the integration of distributed generators to the existing utility grid are as significant as its benefits. The issues are aggravated as the number of grid-connected distributed generators increases. Therefore, power quality demands become stricter to ensure a safe and proper advancement towards the emerging smart grid. In this regard, system protection is the area that is highly affected as the grid-connected distributed generation share in electricity generation increases. Islanding detection, amongst all protection issues, is the most important concern for a power system with high penetration of distributed sources. Islanding occurs when a portion of the distribution network which includes one or more distributed generation units and local loads is disconnected from the remaining portion of the grid. Upon formation of a power island, it remains energized due to the presence of one or more distributed sources. This thesis introduces a new islanding detection technique based on an enhanced multi-layer scheme that shows superior performance over the existing techniques. It provides improved solutions for safety and protection of power systems and distributed sources that are capable of operating in grid-connected mode. The proposed active method offers negligible non-detection zone. It is applicable to micro-grids with a number of distributed generation sources without sacrificing the dynamic response of the system. In addition, the information obtained from the proposed scheme allows for smooth transition to stand-alone operation if required. The proposed technique paves the path towards a comprehensive protection solution for future power networks. The proposed method is converter-resident and all power conversion systems that are operating based on power electronics converters can benefit from this method. The theoretical analysis is presented, and extensive simulation results confirm the validity of the analytical work.

¬FISH DISTRIBUTIONS IN LAKE ONTARIO’S EASTERN BASIN AND THE UPPER ST. LAWRENCE RIVER: AN ANALYSIS USING GIS AND OCCUPANCY MODELLING TECHNIQUES

Predictive models of species distributions are important tools for fisheries management. Unfortunately, these predictive models can be difficult to perform on large waterbodies where fish are difficult to detect and exhaustive sampling is not possible. In recent years the development of Geographic Information Systems (GIS) and new occupancy modelling techniques has improved our ability to predict distributions across landscapes as well as account for imperfect detection. I surveyed the nearshore fish community at 105 sites between Kingston, Ontario and Rockport, Ontario with the objective of modelling geographic and environmental characteristics associated with littoral fish distributions. Occupancy modelling was performed on Round Goby, Yellow perch, and Lepomis spp. Modelling with geographic and environmental covariates revealed the effect of shoreline exposure on nearshore habitat characteristics and the occupancy of Round Goby. Yellow Perch, and Lepomis spp. occupancy was most strongly associated negatively with distance to a wetland. These results are consistent with past research on large lake systems indicate the importance of wetlands and shoreline exposure in determining the fish community of the littoral zone. By examining 3 species with varying rates of occupancy and detection, this study was also able to demonstrate the variable utility of occupancy modelling.

A NEW DC UPS FOR DC POWER DISTRIBUTION SYSTEM IN DATA CENTER

In recent years, the 380V DC and 48V DC distribution systems have been extensively studied for the latest data centers. It is widely believed that the 380V DC system is a very promising candidate because of its lower cable cost compared to the 48V DC system. However, previous studies have not adequately addressed the low reliability issue with the 380V DC systems due to large amount of series connected batteries. In this thesis, a quantitative comparison for the two systems has been presented in terms of efficiency, reliability and cost. A new multi-port DC UPS with both high voltage output and low voltage output is proposed. When utility ac is available, it delivers power to the load through its high voltage output and charges the battery through its low voltage output. When utility ac is off, it boosts the low battery voltage and delivers power to the load form the battery. Thus, the advantages of both systems are combined and the disadvantages of them are avoided. High efficiency is also achieved as only one converter is working in either situation. Details about the design and analysis of the new UPS are presented. For the main AC-DC part of the new UPS, a novel bridgeless three-level single-stage AC-DC converter is proposed. It eliminates the auxiliary circuit for balancing the capacitor voltages and the two bridge rectifier diodes in previous topology. Zero voltage switching, high power factor, and low component stresses are achieved with this topology. Compared to previous topologies, the proposed converter has a lower cost, higher reliability, and higher efficiency. The steady state operation of the converter is analyzed and a decoupled model is proposed for the converter. For the battery side converter as a part of the new UPS, a ZVS bidirectional DC-DC converter based on self-sustained oscillation control is proposed. Frequency control is used to ensure the ZVS operation of all four switches and phase shift control is employed to regulate the converter output power. Detailed analysis of the steady state operation and design of the converter are presented. Theoretical, simulation, and experimental results are presented to verify the effectiveness of the proposed concepts.