Underwater swarm sensor networks: applications, deployment, and medium access communication protocols

Research Doctorate - Doctor of Philosophy (PhD)Our oceans are vast and remain mostly unexplored. Advances in underwater technology have enabled exciting new applications for underwater wireless sensing and monitoring of the environment, fauna, flora, and human activity. The 'game changer', however, for future developments will be when swarms of mobile vehicles are able to undertake autonomous missions as they will increase the usefulness and ability to begin extensive sampling of the earth's oceans to gain an insight into this unknown world. Current solutions have been built around static sensor networks and single ROV’s (remotely operated vehicles) and single AUV’s, which have been typically sparsely deployed. The growth of underwater operations will require data communication between various homogeneous and heterogeneous underwater networks and surface based equipment. This thesis has focused on the communication requirements and medium access control (MAC) algorithms for groups of AUV’s operating in close proximity to each other in a swarm-like fashion as an underwater swarm sensor network (USSN). An investigation into the various applications that would benefit from using a swarm of AUV’s has lead to the classification of Non-time Critical Missions, for mapping and surveying for example and Time Critical Missions for using real-time payload data collection for searching for an object or target. This leads to two topology configurations, a Bus Topology and Cluster Topology respectively that requires different Quality of Service boundaries and MAC methods. The requirement to operate vehicles at very close-range has meant an investigation into the atypical short-range underwater acoustic channel and the spatial-temporal diversity that acoustic communications between devices underwater create which is different from long-range underwater acoustic communications and very different from RF communications in terrestrial settings. This work has also studied the data exchange needs of swarming algorithms with a focus on bio-inspired algorithms that can be used in a group of AUV’s to facilitate the formation of vehicles in particular the Cluster Topology. To maintain swarm synchronisation in both Topologies real-time communication is required in a fully connected but distributed group of underwater vehicles (AUV) operating in an USSN. Two MAC layer protocols were developed for the different application areas: “Adaptive Token Polling MAC (ATP-MAC)” has used an adaption of a token polling ring to provide a decentralised distributed MAC protocol for the Non-time Critical Missions and “Adaptive Space Time – Time Division Multiple Access (AST-TDMA)” protocol that utilising a token to trigger time divisions between vehicles rather than a clock used in TDMA is a fully distributed decentralised algorithm. Both protocols are designed to effectively use a single channel broadcast acoustic environment while incorporating a method to handle the spatial-temporal characteristics experienced underwater. They allow operations to be independent of time synchronization between vehicles and require no prior knowledge of propagation delays. Analytical results presented in this thesis show both the AST-TDMA and ATP-MAC protocols exhibit substantial advantages over the conventional TDMA protocol for the applications that they are designed for. It is shown that the new adaptive protocols outperform TDMA in their ability to disseminate time-sensitive information in a timely manner and therefore allow much higher densities of vehicles to operate in swarm-like networks in both the Bus and Cluster Topologies studied. The AST-TDMA protocol operations in a non-ideal underwater communication channel have also been simulated and the results are presented and analysed. This non-ideal channel includes the simulation of noise and reverberation models. A proposed new type of reverberation, Swarm Reverberation, has also been introduced and incorporated in the analysis

Cytoplasmic Localization of PCV1-VP3 is a CRM1-Independent Function

The viral protein PCV1-VP3 is of key interest in the field of cancer therapeutic development. PCV1-VP3 exhibits cancer-specific apoptotic capabilities in p53-null cancer cells, but not in human primary cells. PCV1-VP3 was discovered to exhibit subcellular localization to the cytoplasm of transformed cells in a manner that is independent of CRM1 nuclear export. It was also revealed that two regions of the protein exhibit differential localization capabilities when separated, which raises further questions regarding the functional capabilities of each region with respect to cancer "sensing" and apoptosis induction

The post-transcriptional regulator CsrA plays a central role in the adaptation of bacterial pathogens to different stages of infection in animal hosts.

International audienceThe importance of Csr post-transcriptional systems is gradually emerging; these systems control a variety of virulence-linked physiological traits in many pathogenic bacteria. This review focuses on the central role that Csr systems play in the pathogenesis of certain bacteria and in the establishment of successful infections in animal hosts. Csr systems appear to control the 'switch' between different physiological states in the infection process; for example switching pathogens from a colonization state to a persistence state. Csr systems are controlled by two-component sensor/regulator systems and by non-coding RNAs. In addition, recent findings suggest that the RNA chaperone Hfq may play an integral role in Csr-mediated bacterial adaptation to the host environment

New Insights Into Dietary Approaches to Potassium Management in Chronic Kidney Disease

Potassium disorders are one of the most common electrolyte abnormalities in patients with chronic kidney disease (CKD), contributing to poor clinical outcomes. Maintaining serum potassium levels within the physiologically normal range is critically important in these patients. Dietary potassium restriction has long been considered a core strategy for the management of chronic hyperkalemia in patients with CKD. However, this has been challenged by recent evidence suggesting a paradigm shift toward fostering more liberalized, plant-based dietary patterns. The advent of novel potassium binders and an improved understanding of gastrointestinal processes involved in potassium homeostasis (e.g., gastrointestinal potassium wasting) may facilitate a paradigm shift and incorporation of heart-healthy potassium-enriched food sources. Nevertheless, uncertainty regarding the risk-benefit of plant-based diets in the context of potassium management in CKD remains, requiring well-designed clinical trials to determine the efficacy of dietary potassium manipulation toward improvement of clinical outcomes in patients with CKD