Greedy methods for approximate graph matching with applications for social network analysis

In this thesis, we study greedy algorithms for approximate sub-graph matching with attributed graphs. Such algorithms find one or multiple copies of a sub-graph pattern from a bigger data graph through approximate matching. One intended application of sub-graph matching method is in Social Network Analysis for detecting potential terrorist groups from known terrorist activity patterns. We propose a new method for approximate sub-graph matching which utilizes degree information to reduce the search space within the incremental greedy search framework. In addition, we have introduced the notion of a “seed” in incremental greedy method that aims to find a good initial partial match. Simulated data based on terrorist profiles database is used in our experiments that compare the computational efficiency and matching accuracy of various methods. The experiment results suggest that with increasing size of the data graph, the efficiency advantage of degree-based method becomes more significant, while degree-based method remains as accurate as incremental greedy. Using a “seed” significantly improves matching accuracy (at the cost of decreased efficiency) when the attribute values in the graphs are deceptively noisy. We have also investigated a method that allows to expand a matched sub-graph from the data graph to include those nodes strongly connected to the current match

Enhancing security in quantum cryptography

Quantum Key Distribution was named as one of the top ten emerging technologies by Technology Review Journal in 2003 in their annual edition. The growth in quantum cryptography since the beginning of the millennium has been expedited by new theories and ideas. The introduction of practical quantum cryptosystems offered by USA based company MagiQTech and its European rival idQuantique has changed the face of cryptography. With active experimental research in USA, Europe, Japan and Singapore, the scope of quantum cryptography seems to be growing daily. When Bennett and Brassard proposed their BB84 protocol in Bangalore in 1984, no one would have guessed the quantum revolution they had launched. Since then, new protocols have been proposed and new theories developed, but BB84 remains the simplest and probably the easiest to implement. Now that the practical implementation of basic quantum cryptography has been achieved, one can be almost certain that new protocols will sooner or later be tested for the efficiency they could provide. We have developed a Classical Authentication Aided (CAA) protocol, which merges the classical authentication policies with quantum transmission to make it even more secure. With the complexities of the authentication policies and the bit to qubit conversion, our system becomes a complex one. We also discuss the possibilities of free space quantum transmission of the protocol instead of only through optical fiber

Fast Detection of Community Structures using Graph Traversal in Social Networks

Finding community structures in social networks is considered to be a challenging task as many of the proposed algorithms are computationally expensive and does not scale well for large graphs. Most of the community detection algorithms proposed till date are unsuitable for applications that would require detection of communities in real-time, especially for massive networks. The Louvain method, which uses modularity maximization to detect clusters, is usually considered to be one of the fastest community detection algorithms even without any provable bound on its running time. We propose a novel graph traversal-based community detection framework, which not only runs faster than the Louvain method but also generates clusters of better quality for most of the benchmark datasets. We show that our algorithms run in O(|V | + |E|) time to create an initial cover before using modularity maximization to get the final cover. Keywords - community detection; Influenced Neighbor Score; brokers; community nodes; communitiesComment: 29 pages, 9 tables, and 13 figures. Accepted in "Knowledge and Information Systems", 201

Churn in Social Networks

Book chapterTelcom networks, online gaming communities, online communities and discussion forums all have one thing in common: they all can be represented by a network of the social links between people. The links in this social network may be based on calls between customers or explicit and implicit connections extracted from online communities, such as friendship relations, shared activity in popular forums, common contributions to discussion threads and so on. While churn in the telcom sector has been studied extensively, no research has been carried out on the general meaning and consequence of churn in online social networks and communities. This chapter aims at filling this gap. Churn is an important factor for social network providers, as it leads to a loss of social capital and ultimately effects service sustainability. Churn undermines the health and ability of communities to self-govern and self-maintain. The risks to digital social networks arise not only through members stopping their activity, but also through significantly reducing activity. This becomes particularly evident where network services rely upon member activity.Not peer reviewe

A review of electromagnetic sensing for healthcare applications

Recent breakthroughs in the fields of antennas, electromagnetic sensors, propagation, and advanced materials have unveiled new opportunities for body area sensing, disease detection, and continuous monitoring. Traditional healthcare approaches not only incur substantial costs but also suffer from inherent drawbacks such as ionizing radiation risks. A range of medical devices, including pacemakers, implants, endoscopy equipment, microwave imaging, and thermal ablation clinical apparatus have greatly benefited from the incorporation of electromagnetic sensors and wireless body area networks. Electromagnetic sensors hold significant potential to transform not only the healthcare sector but also the sports and wearable electronics industries, offering myriad innovative applications. This comprehensive review paper provides an in-depth exploration of the challenges and prospects associated with electromagnetic sensors, including but not limited to microwave probes, resonators, and antennas. We aim to shed light on the potential of these emerging technologies and provide a roadmap for their future development in the context of healthcare and beyond