No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Cell membranes are integral for many biological processes. In addition to containing and protecting cellular contents and maintaining the chemical integrity of the cell, these interfaces host a variety of ligand-receptor interactions. These ligand-receptor interactions are important for cell signaling and transport and the ability to monitor them is key to understanding these processes. In addition, therapeutics and drug discovery is also aided by membrane-specific study, as the majority of drugs target receptors associated with the cell surface. The cell membrane can be effectively mimicked by the use of supported lipid bilayers, which provide a robust platform exhibiting the lateral fluidity and composition associated with cell membranes. The ability to study both ligand-receptor interactions as well as small molecule-membrane interactions on these model membranes is aided by the fact that these assays can be multiplexed and are amenable to use with low sample volumes with high throughput. Our laboratory has recently developed a strategy for fluorescent microscopy studies of ligand-receptor interactions on supported lipid bilayers without the use of fluorescently-labeled analytes. This technique involves the incorporation of pH-sensitive fluorophores into the composition of the supported lipid bilayer as embedded reporter dyes. It was determined that this assay can operate as either a “turn-on” or a “turn-off” sensor depending on the analyte to be detected. It was additionally found that modulating the ionic strength of the operating buffer allows for tuning the operating pH and sensitivity of the assay. This label-free technique can be utilized to monitor small peptide interactions with bilayers containing specific phospholipids. Basic amino acid sequences which are associated with transporting contents across membranes or anti-microbial activity can be monitored binding to negatively charged bilayers without the use of labels. Not only is this a sensitive technique for detecting small peptides, but thermodynamic data can be extracted as well. In a final set of experiments, the interaction of proteins with phosphatidylserine (PS) in supported lipid bilayers is observed by utilizing PS-Cu2+-induced quenching of fluorophores. Disruption of this metal-phospholipid, specifically by Ca2+-dependent protein kinases, results in a turn-on fluorescent assay, which can be used to monitor the binding of the protein to PS and the effects of other metal interference.

Wireless sensor networks have been used in different applications due to the advancement of sensor technology. These uses also have raised different optimization issues. Most of the algorithms proposed as solutions to the various optimization problems are either centralized or distributed which are not ideal for these real life applications. Very few strictly local algorithms for wireless sensor networks exist in the literature. In this thesis, we consider some of these optimization problems of sensor networks, for example, sleep-wake scheduling, mobile dispersion, mobile object monitoring, and gathering problems. We also consider the depth adjustment problem of underwater sensor networks. We design cellular automaton based local algorithms for these problems. The cellular automaton is a bioinspired model used to model different physical systems including wireless sensor networks. One of the main advantages of using cellular automaton based algorithms is that they need very little local information to compute a solution. We perform different simulations and analysis and find that our algorithms are efficient in practice. / Thesis (Ph.D, Computing) -- Queen's University, 2012-11-25 13:37:36.854

The coverage and energy issues are the fundamental problems which prevent the development of wireless sensor networks. In order to accurately evaluate the monitoring quality (coverage), one needs to model the interactive of sensors, phenomenons and the environment. Furthermore, in collaborative with scheduling algorithm and computer optimization, protocols can improve the overall monitoring quality and prolong the lifetime of network. This thesis is an investigation of coverage problem and its relative applications in the wireless sensor networks. We first discuss the realistic of current boolean sensing model and propose an irregular sensing model used to determine the coverage in the area with obstacles. We then investigate a joint problem of maintaining the monitoring quality and extending the lifetime of network by using scheduling schemes. Since the scheduling problem is NP hard, genetic algorithm and Markov decision process are used to determine an achievable optimal result for the joint problem of coverage-preserving and lifetime-prolong. In order to avoid the cost of centralized or distributed scheduling algorithms, a localized coverage-preserving scheduling algorithm is proposed by exploring the construction process of Voronoi diagram. Besides exploring the coverage characteristic in a static wireless sensor network, we investigate the coverage problem when the mobile elements are introduced into network. We consider the single-hop mobile data gathering problem with the energy efficiency and data freshness concerns in a wireless sensor network where the connectivity cannot be maintained. We first investigate the upper/lower bound of the covering time for a single collector to cover the monitoring area. Through our investigation we show that for a bounded rectangle area a hexagon walk could explore the area more efficiently than a random walk when the edges of area are known. We then propose a virtual force mobile model (VFM) in which the energy consumption for data transmission is modeled as a virtual elastic force and used to guide of mobile collectors to move to optimal positions for energy saving.

Over the past decade, wireless sensor networks have gained more research attention for their potential applications in healthcare, defense, environmental monitoring, etc. Due to the strict energy limitation in the sensor node, techniques used for energy saving are necessary for this kind of network. MIMO technology is proven to be an effective method of increasing the channel capacity and supporting higher data rate under a fixed power budget and bit-error-rate requirement. So, wireless sensor networks and MIMO technology are combined and investigated in this thesis. The key contributions of this thesis are detailed below. Firstly, the extended total energy consumption equations for different transmission modes in cluster-based wireless sensor networks are derived. The transmitting energy consumption and the circuit energy consumption are taken into account in both intra-cluster and inter-cluster phases respectively. Secondly, a resource allocation framework is proposed for cluster-based cooperative MIMO on consideration of circuit energy. By introducing two adjusting parameters for the transmitting energy and the time slot allocation between intra-cluster and inter-cluster phases, this framework is designed to achieve the maximum data throughput of the whole system whilst maintaining the capacity and outage probability requirement in these two phases respectively. Thirdly, on comparison of various transmission modes in wireless sensor networks, a relatively energy-efficient mode switching framework is proposed for both single-hop and multi-hop transmissions. Based on the destination and the neighboring nodes’ path-loss, the source node can decide which transmission mode, SISO or cooperative MISO, single-hop or multi-hop, should be chosen. Conditions for each mode switching are investigated. The possible existing area of the cooperative nodes and the relaying nodes can be obtained from this framework.