Creating a secure wireless sensor network involves authenticating and encrypting messages that are sent throughout the network. The communicating nodes must agree on secret keys in order to be able to encrypt packets. Sensor networks do not have many resources and so, achieving such key agreements is a difficult matter. Many key agreement schemes like Diffie-Hellman and public-key based schemes are not suitable for wireless sensor networks. Pre-distribution of secret keys for all pairs of nodes is not viable due to the large amount of memory used when the network size is large. We propose a novel key management system that works with the random key pre-distribution scheme where deployment knowledge is unknown. We show that our system saves users from spending substantial resources when deploying networks. We also test the new system’s memory usage, and security issues. The system and its performance evaluation are presented in this thesis.

Today most computers have powerful multi core processors that can perform many calculations simultaneously. However writing programs that take full advan- tage of the processors in modern day computers can be a challenge. This is due to the challenge of managing shared resources between parallel processing threads. This report documents the development of the Majo language that aims to solve these problems by using abstractions to make parallel programming easier. The model for the abstractions is dividing the program in to what is called nodes. One node represents one thread of execution and nodes are connected to each other by thread safe communication channels. All communication channels are frst in frst out queues. The nodes communicate by pushing and popping values form these queues. The performance of the language was measured and compared to other languages such as Python, Ruby and JavaScript. The tests were based on timing how long it took to generate the Mandelbrot set as well as sorting a list of inte- gers. The language scalability was also tested by seeing how much the execution time decreased by adding more parallel threads. The results from these tests showed that the developed prototype of the language had some unforeseen bugs that slowed down the execution more then expected in some tests. However the scalability test gave encouraging results. For future development the language exe- cution time should be improved by fxing relevant bugs and a more generalized model for concurrency should be developed.

At least 50% of people will develop cancer at some point during their lifetime and half these will end in fatality. Improving patients’ prognosis relies on early and accurate diagnosis and treatment. Current diagnostic methods are based on histopathological analysis and are time-consuming, expensive and require biopsy. Raman spectroscopy can measure subtle biochemical changes and provides a rapid, non-destructive and objective technique that can be used in vivo for identifying pathological changes in tissue samples. This study investigates both a standard Raman spectrometer system and also a Raman needle probe for their use as diagnostic techniques and clinical tools. Oesophageal, femoral and head and neck lymph nodes were analysed in this study. Metastatic lymph nodes from the three areas could be identified from the non-cancer lymph nodes with a sensitivity of 71% and specificity of 89%. Lymphoma was identified from non-cancer lymph nodes with a sensitivity of 64% and specificity of 86%. It was observed that oesophageal nodes often contained carbon particles, clinically diagnosed as anthracosis. These nodes were much harder to study than the femoral or head and neck, due to strong Raman signal detected from the carbon particles. Lymph nodes are embedded in adipose tissue and as a consequence, very strong lipid peaks were frequently observed in spectra. Spectral differences were exhibited in the measurements of the lymph nodes from the three different anatomical regions. A comparison of the point measurements and mapped data showed no difference in classification. Therefore, indicating that just a few measurements can be sufficient enough sampling to represent a specimen, and demonstrates the practicability of Raman use in vivo for rapid analysis. The Raman needle probe feasibility study showed its potential for in vivo use for real-time diagnosis and as a surgical tool to support biopsy. A sensitivity and specificity of 80% and 79% for the identification of non-cancer head and neck lymph nodes from non-cancer provides similar accuracies to the standard Raman approach, therefore supports its viability for use as a diagnostic tool.

Node scheduling is one of the most effective techniques to maximize the lifetime of a wireless sensor network. It is the process of selecting a subset of nodes to monitor the sensor field on behalf of redundant nodes. At every round of the scheduling a small group of nodes are active while the rest of the sensor nodes are in sleep mode. In this thesis, we propose a novel node scheduling solution for wireless sensor networks. The main characteristic of our approach is its independence from location information as well as distance information. Moreover, it does not rely on unrealistic circular radio propagation models. In order to have a comprehensive solution, we have considered different relations between sensing range and transmission range. When these ranges are equal in addition to the case that transmission range is higher than sensing range, we devise a node scheduling scheme based on the concept of Minimum Dominating Set. Two heuristics are presented to determine a collection of minimum dominating sets of the graph of the wireless sensor network. At each round of the scheduling only one set is active. Minimum dominating sets are scheduled to be rotated periodically. Moreover, every set is synchronized prior to the end of its active period in order to minimize the effect of clock drift of sensor nodes. Two components are considered to address node failures during the on-duty period of minimum dominating sets. These are probing environment and adaptive sleeping. The former is responsible for probing the working nodes of the active set to detect any node failure. The latter adjusts the frequency of probing for minimizing the overhead of probing while preserving an adequate level of robustness for discovery of node failure. This framework is based on the PEAS protocol that has been developed by Fan Ye et al. [98, 99]. We propose a different node scheduling scheme with a three-tier architecture for the case that sensing range is higher than transmission range. The coverage tier includes a set of nodes to monitor the region of the interest. We propose a heuristic to determine a collection of d-dominating sets of the graph of the wireless sensor network. At every round of the scheduling one d-dominating set forms the coverage tier. Connectivity tier consists of sensor nodes that relay the data collected at the coverage tier back to the base station. Finally, the coverage management tier is responsible for managing different patterns of coverage such as cyclic or uniform coverage.

Wireless sensor networks consist of many small sensor nodes with sensing, computation, and wireless communications capabilities. Recently, there have been numerous research results in the power consumption for routing protocol. Routing protocols in WSNs might difference depending on the application and network architecture. This paper focuses on reducing the power consumption for routing protocol of wireless sensor networks too. We present a routing protocol called ACRP. sensor nodes will organize many clusters voluntarily. Cluster heads will distribute time slot to the sensor nodes in the same cluster and sensor nodes will transmit data to cluster head in it¡¦s time slot. After the data had been aggregated by cluster heads, they will send the aggregated data to base station through the routing path that had been established. In addition, in order to lengthen the living time of wireless sensor network, the base station will periodically adjust the amount of sensor nodes in all clusters according to the cluster information.

No description available.

In addition to leukocytes, secondary lymphoid organs are populated by non-hematopoietic stromal cells. This diverse group of cells supports lymphocyte migration and homing, facilitates antigen delivery, and promotes T cell survival. However, there is relatively little known about the specific molecules governing the roles that these cells play in regulating dendritic cell (DC) motility and lymph node architecture. Here, we examine the interaction between two molecules, CLEC-2 and podoplanin (PDPN), that are critical for DC migration and maintaining structural integrity of lymph nodes. Together, these studies identify novel functions of lymph node stromal cells and a unique function for PDPN in the immune system. In response detecting an potentially harmful antigen, DCs in peripheral tissues mature and travel to downstream lymph nodes by following chemokine gradients secreted by lymphatic endothelial cells (LECs) and fibroblastic reticular cells (FRCs) present in the lymph node paracortex. We discovered that, in addition to chemokines, DC migration requires CLEC-2 on DCs, as engagement of CLEC-2 with PDPN, which is expressed by LECs and FRCs, incites DC motility and is required for DC entry into the lymphatics, efficient arrival in the lymph node, and migration along the FRC network within the lymph node. Next, we examined the effect of this interaction with respect to the stromal cell. Through a combination approaches, we discovered that PDPN is a master regulator of contractility in FRCs. The fact that FRCs are contractile cells was previously reported, but our study is the first to identify a function for this contractility: upon blockade of PDPN-mediated contractility, lymph nodes became enlarged, the FRC network became more sparse, and there were increased numbers of lymphocytes in the lymph node. Importantly, during an immune response, these changes resulted in more proliferation of antigen-specific T cells and impaired contraction of the lymph node upon resolution of inflammation. Finally, we found that CLEC-2 binding PDPN recapitulated the effect of PDPN deletion. Thus, during an immune response, CLEC-2+ DCs would use PDPN to efficiently migrate to the lymph node and simultaneously cause FRCs to relax and prepare the lymph node for expansion.

Lymph nodes (LNs) are dynamic organs responsible for providing a supportive and centralized environment for the generation of immune response. Utilizing a highly organized network of non-hematopoietic stromal cells, the LN serves as the context in which the immune system collects and presents antigen, promotes innate and adaptive immune interaction, and generates protective cell-mediated and humoral immunity. In this way, proper organization and function of the LN environment is a critical component of effective immunity, and understanding its complexity has direct impact on the ability to generate and modulate primary immune response to specific antigens. To this end, the LN architecture, underlying stromal networks, and environmental and cellular responses to influenza vaccination were investigated. Using novel approaches to conduit imaging, details of the collagen network that comprises the LN scaffolding have been integrated into current understandings of LN architecture. The cellular compartment responsible for the maintenance of that scaffolding, fibroblastic reticular cells (FRCs), have been studied using an induced diptheria toxin receptor model. By specifically ablating the FRC population in mice, their role in the maintenance of T cell homeostasis has been confirmed in vivo. More surprisingly, a disruption of the FRC network resulted in a loss of B cell follicle structure within LNs, and a reduction in humoral immunity to influenza vaccination. These findings led to the identification of a new subset of FRCs which reside in B cell follicles, and serve as a critical source of the B cell survival factor BAFF. Turning towards the hematopoietic response to influenza vaccination, a highly unexpected lymph node resident dendritic cell (LNDC) response has been identified following vaccine antigen deposition within specialized sites in the LN medulla. Rapid migration of LNDCs into these sites optimizes exposure of the population to viral antigen, and de novo synthesis of a CXCL10 chemokine gradient by activated LNDCs ensures efficient antigen specific \(CD4^+\) T cell response, and protective humoral immunity - independent of migratory dendritic cell status. Altogether, these studies highlight a highly dynamic, responsive LN environment with direct influence on primary immune response - the understanding of which has broad implications in vaccine biology.

Coverage in a Wireless Sensor Network reflects how well a sensor network monitors an area. Many times it is impossible to provide full coverage. The key challenges are to prolong the lifetime and ensure connectivity to provide a stable network. In this thesis we first define p-percent coverage problem in which we require only p% of the whole area to be monitored. We propose two algorithms, Connected P-Percent Coverage Depth First Search (CpPCA-DFS) and Connected P-Percent Connected Dominating Set (CpPCA-CDS). Through simulations we then compare and analyze them for their efficiency and lifetime. Finally in conclusion we prove that CpPCA-CDS provides 5 to 20 percent better active node ratio at low density. At high node density it achieves better distribution of covered area however the lifetime is only 5 to10 percent shorter then CpPCA-DFS. Overall CpPCA-CDS provides up to 30 percent better distribution of covered area.

Vystyti mikrosensorinio tinklo duomenų perdavimą racionalaus maršrutizavimo sistemoje. Minimizuoti perdavimų skaičių, sudarant bevielį mikrosensorinį tinklą. Taip pat, trumpinti skaičiavimo procesus, kai mazgai turi atlikti racionalų maršrutizavimą. Bevielio mikrosensorinio tinklo trumpiausio kelio radimas turi būti paprastai realizuojamas ir skaičiuojamas. / In this paper it is described a method of creation of the shortest path algorithm for wireless sensor networks. Algorithm computes optimal shortest path and works on any wireless sensor networks topology. One of the limitations of wireless sensor nodes is their inherent limited energy resource. The limited available energy of sensor nodes is mainly problem making communication and computational processing. An energy efficient routing protocol can limit the number of nodes transmissions and the computational complexity of finding the shortest routing path. In the experimental part, the correct functionality of the algorithm is evaluated and the results are analized.