Ma Yu Tak. / Thesis submitted in: October 2006. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 70-73). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- IEEE 802.11 Standard --- p.4 / Chapter 3 --- Vulnerabilities of IEEE 802.11 --- p.8 / Chapter 3.1 --- Authentication Vulnerabilities --- p.8 / Chapter 3.2 --- Medium Access Control Vulnerabilities --- p.9 / Chapter 3.3 --- Proposed Counter-Measures --- p.10 / Chapter 4 --- Denial-of-Service Attacks by Exploiting the MAC protocol --- p.12 / Chapter 5 --- Simulation Results --- p.20 / Chapter 5.1 --- General DoS Attack Simulations --- p.21 / Chapter 5.1.1 --- Topology 1: A Simple Wireless Network --- p.21 / Chapter 5.1.2 --- Topology 2: Wireless Network in Ad-Hoc Mode --- p.24 / Chapter 5.1.3 --- Topology 3: Network with Hidden Node Problem --- p.29 / Chapter 5.2 --- Targeted DoS Attack Simulations --- p.32 / Chapter 5.2.1 --- Topology 4: A Simple Wireless Network --- p.32 / Chapter 5.2.2 --- Topology 4: A Simple Network with Reversed TCP Flows --- p.38 / Chapter 6 --- Detecting and Solving the Attacks --- p.41 / Chapter 6.1 --- Detection of Attacker --- p.41 / Chapter 6.1.1 --- Detecting General DoS Attackers --- p.41 / Chapter 6.1.2 --- Detecting Targeted DoS Attackers --- p.44 / Chapter 6.2 --- Possible Solutions to the DoS Attacks --- p.53 / Bibliography --- p.70 / Chapter A --- TCP Exponential Backoff with Non-Zero Throughput --- p.74 / Chapter A.1 --- TCP Exponential Backoff Background --- p.74 / Chapter A.2 --- Illustration by Simulation --- p.76 / Chapter A.3 --- Implication of the Finding --- p.77 / Chapter B --- Idle Sense in networks with Hidden Node Problem --- p.79 / Chapter B.1 --- Simulation findings --- p.79 / Chapter B.1.1 --- Four hidden nodes case --- p.79 / Chapter B.1.2 --- Analysis of the simulation results --- p.81 / Chapter B.1.3 --- Study of mixed node types --- p.82 / Chapter B.2 --- Possible approaches to use Idle Sense with Hidden Node Problem --- p.84 / Chapter B.2.1 --- Performance Evaluation --- p.88 / Chapter B.3 --- Conclusions --- p.91

In the expanding spectrum marketplace, there has been a long term evolution towards more market€“oriented mechanisms, such as Opportunistic Spectrum Access (OSA), enabled through Cognitive Radio (CR) technology. However, the potential of CR technologies to revolutionize wireless communications, also introduces challenges based upon the potentially non€“deterministic CR behaviour in the Electrospace. While establishing and enforcing compliance to spectrum etiquette rules are essential to realization of successful OSA networks in the future, there has only been recent increased research activity into enforcement. This dissertation presents novel work on the spectrum monitoring aspect, which is crucial to effective enforcement of OSA. An overview of the challenges faced by current compliance monitoring methods is first presented. A framework is then proposed for the use of random spectral sampling techniques to reduce data collection complexity in wideband sensing scenarios. This approach is recommended as an alternative to Compressed Sensing (CS) techniques for wideband spectral occupancy estimation, which may be difficult to utilize in many practical congested scenarios where compliance monitoring is required. Next, a low€“cost computational approach to online randomized temporal sensing deployment is presented for characterization of temporal spectrum occupancy in cognitive radio scenarios. The random sensing approach is demonstrated and its performance is compared to CS€“based approach for occupancy estimation. A novel frame€“based sampling inversion technique is then presented for cases when it is necessary to track the temporal behaviour of individual CRs or CR networks. Parameters from randomly sampled Physical Layer Convergence Protocol (PLCP) data frames are used to reconstruct occupancy statistics, taking account of missed frames due to sampling design, sensor limitations and frame errors. Finally, investigations into the use of distributed and mobile spectrum sensing to collect spatial diversity to improve the above techniques are presented, for several common monitoring tasks in spectrum enforcement. Specifically, focus is upon techniques for achieving consensus in dynamic topologies such as in mobile sensing scenarios.

The present study examines the nature of bilingual lexical access using category fluency across five language combinations using 109 healthy speakers of Hindi-English, Kannada-English, Mandarin-English, Spanish-English, and Turkish-English. Participants completed a category fluency task in each of their languages in three main categories (animals, clothing, food), each with two subcategories, as well as a language use questionnaire assessing their proficiency in each of their languages. Multivariate analyses of variance revealed that the average number of correct items named in the category fluency task across the three main categories varied across the different groups for English items only. A series of repeated-measures analyses of covariance revealed that the exposure component that had been extracted from the language use questionnaire using a principal component analysis significantly affected the average number of items named across the three main categories. When the effect of exposure was controlled, the effect of language combination was no longer significant. A regression analysis showed that the relative amount of exposure participants had to each of their languages predicted participants’ relative performance in each language. Additional multivariate analyses of variance found significant differences in the number of correct items named in each main category and subcategory in both English and participants’ other language based on language combination. Overall, these results demonstrate the effects of particular language combinations on bilingual lexical access and provide important insights into the role of proficiency on access.

BACKGROUND: Naloxone, an opioid antagonist, offers a powerful tool for preventing opioid overdose deaths. Because studies have shown opioid overdose education and naloxone distribution (OEND) programs to be a safe, feasible, and effective intervention, several policymakers and public health agencies have advocated for broader access to this life-saving medication. Community health centers (CHCs) are a promising location for expanding naloxone access. This investigation examined the experience of CHC-based HIV primary care teams with a variety of overdose education and naloxone access (OENA) strategies in order to inform future dissemination efforts. METHODS: A mixed methods study was conducted with eight CHCs located in Massachusetts communities experiencing high opioid overdose fatality rates. Individual and group interviews with 29 clinic staff members; clinic and participant surveys; and document review were used to elucidate the OENA strategies. The Consolidated Framework for Implementation Research guided the data collection process and subsequent analysis, which revealed several factors supporting or hindering implementation of OENA activities in CHC primary care settings. RESULTS: Operating in a facilitative state policy environment, the CHCs utilized a mix of approaches to OENA: providing clinic-based services, issuing prescriptions, utilizing pharmacy standing orders, and making referrals to existing community-based OEND programs. With prescribers having limited time and competing priorities, nurses, health educators, and other staff played a prominent role in OENA. Pharmacies also served as important access points for patients and community residents. Several strategies were used to engage patients, including active outreach, partnerships with external organizations, and efforts to destigmatize substance use disorders. Clinic staff participation was enhanced through leadership support for harm reduction approaches, ongoing training, peer modeling, and information sharing. CONCLUSIONS: This study demonstrated that OENA can be integrated into CHC primary care services, adapted to the clinic context, and modified as needed. Successful implementation required a systems-level response, grounded in a team-based care model and a consideration of patient needs. The process for naloxone reimbursement needs to be determined to minimize CHC or patient barriers and ensure sustainability. Clinic training and technical assistance plans should be customized according to the staff members’ potential roles and their stage of readiness.

Kwan Ho-yuet. / "April 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 98-[103]). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

This thesis investigates the human-factor problems in password authentication and proposes some usable solutions to these problems by focusing on both forms of knowledge based authentication: textual passwords and graphical passwords. It includes a range of empirical studies to examine users' password-related behaviour and practices in authentication, and helps users to adopt secure password behaviour. This thesis consists of two parts. The first part focuses on traditional text-based passwords. Design flaws and usability issues of existing text-password mechanisms used by many organisations cause employees to adopt insecure password practices. The first work in this thesis investigates the reasons for employees' lack of motivation regarding password protection against security failures. An empirical study is conducted to identify the factors causing employees' insecure behaviours in organisations, and several persuasion strategies are tested to persuade employees to use passwords more safely. The results of the study revealed that some persuasion strategies are effective in motivating users to adopt good password practices. The study also found that the failure of password policies and authentication schemes deployed by organisations is a common problem among the organisations. Considering the results of the first study, in the second work of this thesis, a password guideline/advice study is conducted to help users to create stronger and more memorable passwords. A password guideline including a number of password creation methods and a persuasive message is proposed, and its effectiveness in improving the strength of user-chosen passwords is evaluated. The results show that the users who received the proposed guideline produced stronger and more memorable passwords than the users followed the usual password restrictions while creating their passwords. The results also demonstrate that the given password creation methods can be helpful and inspirational for users to create their own encryption formula. All these works reveal the weaknesses of user-chosen textual passwords and inefficacy of existing text-based password mechanisms. Although these studies show that text-based password mechanisms can be strengthened, they are still problematic where usability is concerned. Thus, the second part of this thesis focuses on another form of knowledge-based authentication: graphical passwords. A novel hybrid authentication scheme integrating text and images is introduced to minimise the brute force and shoulder surfing attacks which text and graphical passwords suffer. In the last work of this thesis, the proposed hybrid scheme is implemented and evaluated. The evaluation shows that the proposed scheme provides security and usability at the same time, and it also makes the password creation process enjoyable for users. In summary, the thesis contributes to the analysis of some key security and usability problems which arise in knowledge-based authentication. A series of empirical studies has been conducted. Based on their results, usable solutions to the human-factor problems in password-based authentication are proposed and evaluated.

High school marching bands have several performance options beyond the Friday night football game. These options range from non-competitive regional festivals to performance circuits that culminate in a final national contest. All of these extra-curricular events require resources such as funding, equipment, staffing, and parental involvement (Corral, 2001). The fundamental question was created to investigate opportunities available for participation in music regardless of socioeconomic status, geographic location, etc. Participation in music was explored from the vantage point of marching band – one of the most resource intensive programs in music. Marching band was used in this study because the activity often requires resources that go above and beyond what many administrators, parents, and some directors claim justifiable. The purpose of this causal-comparative study was to examine the effects that resources, financial and otherwise, have on directors’ decisions to participate in marching band competitions. High school marching bands from across the United States were compared to determine the amount of finances and resources invested by each program. The purpose was to find out if resources play a role in a band director’s decision to compete at various national or non-national events. Students who desire to participate in music should have the opportunity to participate in any extra-curricular event without regard to economic distinction. Even though marching arts are not offered at all high schools, those who do commit to investing extreme time and resources to the activity. The nature of marching band, coupled with the relatively small amount of scholarly research on marching bands and resources, made it a unique scenario worthy of further inquiry.

Wars fought over oil have characterized the latter half of the past century, the repercussions of which have been felt in every corner of the globe. Although war remains a constant, attention is transitioning away from oil to another natural resource. As we move through the 21st century, water wars are now at the forefront of global conflicts. Fighting over access to this vital resource is nothing new. Allen Snitow, a documentary filmmaker and journalist claims: “For thousands of years, the conflicts between towns and countries have been defined by the battle over who gets to use the stream. The word rival and river have the same root.”1 Disputes over access to water have been inevitable because of human’s dependence on this natural resource for sustenance. The lack of a substitution for water makes the world water crisis a threat requiring immediate attention and innovative solutions. The assumed responsibility of the government to provide sustainable solutions has proven ineffective in its failure to protect the human right to water. As a world water crisis, there is a need for a more cohesive management approach. Identifying and implementing effective and equitable approaches to water management is a highly debated subject across many disciplines. A common approach to combating issues of access to potable water involves the private sector and its reliance on the market. Alternatively, some advocate for treating water as a public or community good to avoid the commodification of an essential resource. Through various examples and a fleshed out case study, I illustrate how solutions to the water crisis are not determined by theoretical frameworks, but are shaped by the viability of the approaches in a given region. The factors that influence the feasibility of an approach include: the availability of water resources and other geographical or environmental circumstances; the political stability or corruption within the government; the degree of established infrastructure; determination of who the government is responsible for providing water services to; and the specific cultural needs of different groups. By analyzing the aforementioned theoretical perspectives on water management through a lens that considers each of these factors, I attempt to identify and analyze the context for which these approaches are appropriate and effective in providing equitable access to clean water. The political, economic, cultural and geographical contexts of a region are critical in considering how to best alleviate issues of access to potable water. In addition, I argue that across all of these diverse contexts in which we identify water access issues, it is invariably necessary to treat water as a public good in order to protect the human right to water. 1 Alan Snitow, Deborah Kaufman, and Michael Fox, Thirst: Fighting the corporate theft of our water, (San Francisco: Jossey-Bass, 2007), 3.

Doctor of Social Work / This doctoral thesis presents the findings of a qualitative research project which examines the impact of university study on a group of twenty female and male mature-age students at the University of Newcastle, Australia, who have entered university via a non-traditional pathway. The students who are the subject of this thesis are in the second to final years of their undergraduate degree programs and have all faced significant hurdles in gaining university entrance and persevering with their studies. The majority have come from lower socio-economic backgrounds with little, if any, family history of higher education and little positive experience of prior study. Postmodern feminist theory has primarily informed this research, using a narrative method to gather the data, analyse the results and present the findings. This thesis describes the experiences of the twenty individuals, derived from their individual narratives. As such, it gives voice to their stories: their triumphs and achievements as well as their struggles. It examines the gender issues that are at work in the shaping of their experiences, including the ways in which gender affected the type and extent of help and support on which they could rely. It highlights the transformative nature of these experiences for each of the students in this cohort, as well as potentially the next generation, and makes some tentative connections between these individual experiences and the experiences of the wider mature-age university student population. The narratives that individuals tell are socially and culturally located. Hence it is likely that the experiences of these twenty students may reflect, at least to some extent, the experiences of other mature-age students within a similar culture. The findings of this research also highlight the important role that higher education institutions can play, not only in widening access to higher education, but also in encouraging and assisting students, from a diverse range of backgrounds, to participate fully in higher education and achieve their goals.

The introduction of cellular wireless systems in the 1980s has resulted in a huge demand for personal communication services. This demand has made larger capacity systems necessary. This has been partially satisfied by the introduction of second generation digital systems. New third generation systems are now under going standardisation and will require even more efficient utilisation of the spectrum if the high bandwidth features and larger capacity are to become a reality. Motivated by these growing requirements we discuss methods of achieving large improvements in spectral efficiency and performance. Multiple-user communications over a channel can only be achieved with some form of diversity. In this work we point out that the efficient utilisation of the dimensions of space, time, and frequency will ultimately maximise the system capacity of a multiple-user system. We apply our receiver techniques solely to the base-station design where capacity limitations are currently present. We note however, that some of these techniques could also be applied at the mobile terminal receiver. We primarily focus our attention on the direct-sequence code-division multiple-access (DS/CDMA) channel, since this channel is inherently interference limited by other users in the cell of interest. We exploit a new powerful channel coding technique named " turbo coding" for its iterative decoding approach. We show how we can substitute the inner convolutional code of a turbo code encoder with the CDMA channel. By " iterative detection/decoding" or " turbo equalisation" at the receiver we achieve performance results which show the interference from other users to approach complete removal. We develop and analyse a new, low complexity, iterative interference canceller/decoder. This receiver has complexity per user linear with the memory of the channel and independent of the number of users in the system. We extend this receiver to more realistic channels that are asynchronous and include multi-path, and include spatial diversity by using an antenna array at the receiver. The CDMA channel we study exclusively uses randomly generated spreading codes. With this channel model we still achieve single user performance (no interference from other users) with a 10logL gain from L antenna elements and a gain of up to 10logP from P multi-path components. With any new receiver design, sensitivity to channel parameter errors is of paramount interest. We find that the sensitivity of our receiver is low with respect to the parameter errors induced. This is as we desire for a realisable receiver design. Finally we investigate the application of this new iterative interference canceller/decoder receiver to a number of other interference channels. These include the intersymbol interference (ISI) channel, partial response signalling (PRS), and continuous phase modulation (CPM). For these channels excellent performance improvement is generally achieved by the utilisation of the iterative interference canceller/decoder solution. / Thesis (PhD)--University of South Australia, 1999