This Ph.D. dissertation examined the effects of bacterial DNA on immune surveillance in ovine lymph nodes (LN). The first study identified long-term changes in lymph nodes following exposure to plasmid DNA. Treated lymph nodes were heavier and had larger medullary areas. Furthermore, medullary cord thickness and medullary sinus width as well as germinal center size and number were increased in plasmid treated lymph nodes.<p>To determine whether bacterial DNA altered cell trafficking through lymph nodes, the efferent lymphatic of the prescapular LN of sheep was cannulated and cells were collected. Intradermal injection of as little as 4 ìg of plasmid DNA expressing the green fluorescent protein of jellyfish (eGFP) caused a marked increase in the cell trafficking through the prescapular lymph node. A dose-dependent facet existed for this response, as the increase in cell trafficking response persisted longer with 40 ìg or 400 ìg of plasmid-eGFP than with 4 ìg. This increased cell trafficking was independent of green fluorescent protein expression as both pCAN1-eGFP and pCAN1 induced similar responses.<p>Increased cell traffic induced by bacterial DNA was further characterized by determining whether bacterial DNA form was critical for this response. Treatment with intact plasmid (circular) DNA induced the greatest increase in cell traffic. In contrast, when plasmid DNA was digested with restriction enzymes into linear fragments of DNA, then cell trafficking was not significantly increased. <p>Numerous studies have shown that immunostimulatory guanosine-cytosine (CpG) motifs activate cells in vitro and can improve protective immune responses in vivo . Therefore we tested the hypothesis that the presence of immunostimulatory CpG motifs within plasmids was responsible for altering cell trafficking. It was shown that plasmids with added immunostimulatory CpG sequences affected cell trafficking in a dose-dependent manner. The injection of 40 ìg of pBISIA-88 caused an increase in cell trafficking while injecting 400 ìg pBISIA-88 failed to increase cell flow above control levels.<p>Analysis of cell populations collected in efferent lymph gives insight into treatment effects on immune surveillance. This is well-studied following treatment with antigen and in general, antigen induces a selective movement of cells into lymph that occurs 24 hours post-treatment. In contrast, plasmid DNA induced a rapid, non-selective movement of lymphocytes through the lymph node, suggesting that bacterial DNA and antigen may affect cell trafficking by different mechanisms and thereby have distinct effects on immune surveillance.<p>Short-term effects of bacterial DNA on lymph node architecture and cellular composition were also investigated to determine whether an increase in cell trafficking was associated with structural changes within the lymph node. While it was shown that bacterial DNA induced changes within a lymph node, including and increased number of germinal centers and an increased frequency of CD72*CD21* B cells, these changes were not correlated to increased cell trafficking.<p>In summary, bacterial DNA altered immune surveillance in sheep lymph nodes by changing cell traffic and lymph node architecture and composition. Many of these responses differed from responses observed by others following antigen treatment. The present observations suggest that bacterial DNA can function as an important signal to modulate immune surveillance and host responses to infections by pathogens.

This Ph.D. dissertation examined the effects of bacterial DNA on immune surveillance in ovine lymph nodes (LN). The first study identified long-term changes in lymph nodes following exposure to plasmid DNA. Treated lymph nodes were heavier and had larger medullary areas. Furthermore, medullary cord thickness and medullary sinus width as well as germinal center size and number were increased in plasmid treated lymph nodes.<p>To determine whether bacterial DNA altered cell trafficking through lymph nodes, the efferent lymphatic of the prescapular LN of sheep was cannulated and cells were collected. Intradermal injection of as little as 4 ìg of plasmid DNA expressing the green fluorescent protein of jellyfish (eGFP) caused a marked increase in the cell trafficking through the prescapular lymph node. A dose-dependent facet existed for this response, as the increase in cell trafficking response persisted longer with 40 ìg or 400 ìg of plasmid-eGFP than with 4 ìg. This increased cell trafficking was independent of green fluorescent protein expression as both pCAN1-eGFP and pCAN1 induced similar responses.<p>Increased cell traffic induced by bacterial DNA was further characterized by determining whether bacterial DNA form was critical for this response. Treatment with intact plasmid (circular) DNA induced the greatest increase in cell traffic. In contrast, when plasmid DNA was digested with restriction enzymes into linear fragments of DNA, then cell trafficking was not significantly increased. <p>Numerous studies have shown that immunostimulatory guanosine-cytosine (CpG) motifs activate cells in vitro and can improve protective immune responses in vivo . Therefore we tested the hypothesis that the presence of immunostimulatory CpG motifs within plasmids was responsible for altering cell trafficking. It was shown that plasmids with added immunostimulatory CpG sequences affected cell trafficking in a dose-dependent manner. The injection of 40 ìg of pBISIA-88 caused an increase in cell trafficking while injecting 400 ìg pBISIA-88 failed to increase cell flow above control levels.<p>Analysis of cell populations collected in efferent lymph gives insight into treatment effects on immune surveillance. This is well-studied following treatment with antigen and in general, antigen induces a selective movement of cells into lymph that occurs 24 hours post-treatment. In contrast, plasmid DNA induced a rapid, non-selective movement of lymphocytes through the lymph node, suggesting that bacterial DNA and antigen may affect cell trafficking by different mechanisms and thereby have distinct effects on immune surveillance.<p>Short-term effects of bacterial DNA on lymph node architecture and cellular composition were also investigated to determine whether an increase in cell trafficking was associated with structural changes within the lymph node. While it was shown that bacterial DNA induced changes within a lymph node, including and increased number of germinal centers and an increased frequency of CD72*CD21* B cells, these changes were not correlated to increased cell trafficking.<p>In summary, bacterial DNA altered immune surveillance in sheep lymph nodes by changing cell traffic and lymph node architecture and composition. Many of these responses differed from responses observed by others following antigen treatment. The present observations suggest that bacterial DNA can function as an important signal to modulate immune surveillance and host responses to infections by pathogens.

The objective of the proposed research is to analyze and develop energy optimized design techniques that can improve the operating efficiency for a wireless sensor device. To enhance the operating efficiency, all active functional blocks in a system should focus on energy conservation while achieving the required tasks. In addition, variations in the operating condition should be properly observed and compensated. Otherwise, a wireless sensor device would consume unnecessary energy for a given task or too little energy to meet the requirements. In this research, design strategies and some new circuit topologies are discussed in terms of ultra-low energy constraints. In particular, the signal processing unit, the memory unit, and the power unit in a conventional wireless sensor device will be main focus. As an example of the signal processing unit, a subthreshold current mode computation system has been designed and tested to prove the "low power consumption" feature of analog signal processing. For the memory unit, conventional SRAM cells are compared to a new fully-gated 10T-SRAM cell. For the power unit, a semi-active high-efficient CMOS rectifier with a reverse leakage control has been developed. It employs a cross-coupled NMOS pair and two leakage control comparators to reduce reverse charge leakage currents. In addition, the adaptive body bias control technique is utilized to improve the reliability of the rectifier. In addition, a novel link-variation sensing technique is proposed. The proposed technique can evaluate operational disturbances such as component mismatches and displacement variations so that the performance of a wireless sensor device in the actual environment can be close to the optimum without wasting an excessive amount of energy.

M. Tech. Electrical Engineering. / Aims to develope a detection procedure whose objective function is to try as much as possible not to impact heavily on the resource constrained sensor nodes.

My project was to develop a hardware and software platform consisting of client nodes and a base station interconnected wirelessly. The nodes collect physical data for their local environment - I implemented a temperature measurement and a battery level reading. These measurements were placed in a packet which was then relayed via other nodes to the base station. The base station is attached to a USB dongle to a computer which collects the data and stores it into a log file for later analysis. In designing such a network, my goal was to learn about routing protocols, take key concepts learned in classes, such as different modulation schemes and the study of wireless degradation in various environments due to reflections and interference, and explore an implementation of a commercial wireless system. Such a system could be modified to fit a multitude of applications such as environmental data collection for farmers, low power networks for data communication for disaster recovery teams, or sensor networks or implemented in a house to collect data over long period and analyze variances in different regions and implement automated control through a feedback loop. To implement my code, I used TI’s EZ430-RF2500. This development kit contains the TI MSP430F2274, a 16MHz, 16 bit RISC processor which in active mode only pulls 270µA. The MSP430F2274 is coupled with a TI CC2500 which is a 2.4GHz RF transceiver used to communicate with the other devices. The EZ430-RF2500 connects to the computer via a USB dongle with proprietary firmware loaded which allows for programming and serial communication with the computer. I built a network using three devices; one connected to a laptop acting as the access point and two remote devices powered by two AAA batteries acting as the end devices or clients. I performed a study of packet success rates in different environments, specifically inside a residential home, outside in a residential neighborhood and in a rural area. In close ranges (distances less than 50’) there were no noticeable differences in performance between the three environments. I could not exceed 50’ inside the residential environment due to the size of the tested house. Beyond 50’ in the two outside environments, the results surprisingly did not differ greatly; successful transmissions were accomplished at distances only 10’ further in Town Lake; that is that successful transmissions were capable up to 95’ at Town Lake and 85’ in my uban neighborhood. As a representative finding, in the urban environment, the clients were successfully transmitting at an 80% success rate at 80’ pulling 84.48mW (26.4mA at 3.2V) while transmitting with 2-FSK. / text

The objective of this dissertation is to develop task scheduling guidelines and algorithms for wireless sensor nodes that harvest energy from ambient environment and use supercapacitor based storage systems to buffer the harvested energy. This dissertation makes five contributions. First, a physics based equivalent circuit model for supercapacitors is developed. The variable leakage resistance (VLR) model takes into account three mechanisms of supercapacitors: voltage dependency of capacitance, charge redistribution, and self-discharge. Second, the effects of time and supercapacitor initial state on supercapacitor voltage change and energy loss during charge redistribution are investigated. Third, the task scheduling problem in supercapacitor based environmentally powered wireless sensor nodes is studied qualitatively. The impacts of supercapacitor state and energy harvesting on task scheduling are examined. Task scheduling rules are developed. Fourth, the task scheduling problem in supercapacitor based environmentally powered wireless sensor nodes is studied quantitatively. The modified earliest deadline first (MEDF) algorithm is developed to schedule nonpreemptable tasks without precedence constraints. Finally, the modified first in first out (MFIFO) algorithm is proposed to schedule nonpreemptable tasks with precedence constraints. The MEDF and MFIFO algorithms take into account energy constraints of tasks in addition to timing constraints. The MEDF and MFIFO algorithms improve the energy performance and maintain the timing performance of the earliest deadline first (EDF) and first in first out (FIFO) algorithms, respectively.

No description available.

Arterial routes are key structuring components of the urban structure. These routes perform vital functions, including the connectivity of nodes or nodal areas, providing access to urban opportunities, linking metropolitan / municipal areas and providing access to the public transportation system. In order to protect the functionality of these routes, which primarily relates to a mobility function, development along these routes should be controlled. The formulation of policies for development along arterial routes is vital to ensure sustainable, integrated development along these routes without negatively impacting on the urban structure as a whole. A number of challenges are experienced during the formulation–process of these policies, especially since development along these routes is multi–faceted in nature. A case study of Ontdekkers Road, which is a major arterial route located within the City of Johannesburg, is used as the main point of departure. A comparison of the three sections of the route extending from Krugersdorp to Johannesburg (i.e. Voortrekker, Ontdekkers and Main Road) and the applicable development policies provides insight into the key challenges experienced during the policy–formulation process and the implementation of these policies. The study provides key recommendations in response to the challenges experienced along major arterial routes. The recommendations predominantly relate to the multi–faceted nature of development along these routes; the necessity of an interdisciplinary approach to policy–formulation; the importance of comprehensive public participation that involves the relevant stakeholders, professionals and authorities; and the continuous interaction between neighbouring municipalities to identify cross–border issues and co–ordinate planning initiatives. The dynamic nature of development along arterial routes necessitates dynamic policies that consider changing social, economic and physical conditions. To this end, the study recommends the review of development policies on an annual basis and the implementation of contingency–based planning. / Thesis (M.Art. et Scien. (Town and Regional Planning))--North-West University, Potchefstroom Campus, 2011.

Arterial routes are key structuring components of the urban structure. These routes perform vital functions, including the connectivity of nodes or nodal areas, providing access to urban opportunities, linking metropolitan / municipal areas and providing access to the public transportation system. In order to protect the functionality of these routes, which primarily relates to a mobility function, development along these routes should be controlled. The formulation of policies for development along arterial routes is vital to ensure sustainable, integrated development along these routes without negatively impacting on the urban structure as a whole. A number of challenges are experienced during the formulation–process of these policies, especially since development along these routes is multi–faceted in nature. A case study of Ontdekkers Road, which is a major arterial route located within the City of Johannesburg, is used as the main point of departure. A comparison of the three sections of the route extending from Krugersdorp to Johannesburg (i.e. Voortrekker, Ontdekkers and Main Road) and the applicable development policies provides insight into the key challenges experienced during the policy–formulation process and the implementation of these policies. The study provides key recommendations in response to the challenges experienced along major arterial routes. The recommendations predominantly relate to the multi–faceted nature of development along these routes; the necessity of an interdisciplinary approach to policy–formulation; the importance of comprehensive public participation that involves the relevant stakeholders, professionals and authorities; and the continuous interaction between neighbouring municipalities to identify cross–border issues and co–ordinate planning initiatives. The dynamic nature of development along arterial routes necessitates dynamic policies that consider changing social, economic and physical conditions. To this end, the study recommends the review of development policies on an annual basis and the implementation of contingency–based planning. / Thesis (M.Art. et Scien. (Town and Regional Planning))--North-West University, Potchefstroom Campus, 2011.

A completely satisfactory water distribution network should fulfill its basic requirements such as providing the expected quality and quantity of water with the desired residual pressures during its lifetime. A water distribution network should accommodate the abnormal conditions caused by failures. These types of failures can be classified into two groups / mechanical failures and hydraulic failures. Mechanical failure is caused due to malfunctioning of the network elements such as pipe breakage, power outage and pump failure. On the other hand, hydraulic failure, considers system failure due to distributed flow and pressure head which are inadequate at one or more demand points.This study deals with the calculation of the hydraulic system reliability of an existing water distribution network regarding the Modified Chandapillai model while calculating the partially satisfied nodes. A case study was carried out on a part of Ankara Water Distribution Network, N8-1. After the modeling of the network, skeletonization and determination of nodal service areas were carried out. The daily demand curves for the area were drawn using the data that were taken from SCADA of the water utility. The daily demand curves of different days were joined and one representative mean daily demand curve together with the standard deviation values was obtained. The friction coefficient values of the pipes and storage tank water elevation were taken as other uncertainty parameters for the model. Bao and Mays (1990) approach were carried together with the hydraulic network solver program prepared by Nohutcu (2002) based on Modified Chandapillai model. The sensitivity analysis for the effects of system characteristics and model assumptions were carried out to see the effects of the parameters on the calculations and to investigate the way of improving the hydraulic reliability of the network. The storage tank should be located at a higher level for improving the reliability of the network. Also having the storage tank water level nearly full level helps in improving the reliability in daily management. Moreover, the hydraulic system reliability is highly dependent on the pumps as the lowest reliability factors were the ones with the no pump scenarios. Determining the required pressures for nodes are very important since they are the dominant factors that effects the reliability calculations. On the other hand, friction coefficient parameters and type of probability distribution function do not have dominant effect on the results. Results of this study were helpful to see the effects of different parameters on the hydraulic reliability calculations and for assessment of the methods for improving the reliability for the network.