Metric spaces, which generalise the properties of commonly-encountered physical and abstract spaces into a mathematical framework, frequently occur in computer science applications. Three major kinds of questions about metric spaces are considered here: the intrinsic dimensionality of a distribution, the maximum number of distance permutations, and the difficulty of reverse similarity search. Intrinsic dimensionality measures the tendency for points to be equidistant, which is diagnostic of high-dimensional spaces. Distance permutations describe the order in which a set of fixed sites appears while moving away from a chosen point; the number of distinct permutations determines the amount of storage space required by some kinds of indexing data structure. Reverse similarity search problems are constraint satisfaction problems derived from distance-based index structures. Their difficulty reveals details of the structure of the space. Theoretical and experimental results are given for these three questions in a wide range of metric spaces, with commentary on the consequences for computer science applications and additional related results where appropriate.

<p>This dissertation investigates the economic behavior of families in developing settings. Utilizing uniquely rich, longitudinal survey data from Indonesia, it demonstrates the complexity of market environments facing rural households, as well as the importance of extended family networks in determining the health and well-being of young children. These essays serve as an illustration of advances in development economics that are possible when fundamental models are revisited and examined with new longitudinal data. The results of these exercises are important not only for updating economic models of behavior, but for what they reveal about the complexities of decision making, and for the effective design and evaluation of development policy around the world.</p> / Dissertation

Given a connected oriented graph D, we say that a subset S of V(D) is convex in D if, for every pair of vertices x, y in S, the vertex set of every x-y geodesic (x-y shortest dipath) and y-x geodesic in D is contained in S. The convexity number con (D) of a nontrivial connected oriented graph D is the maximum cardinality of a proper convex set of D. Let S_{C}(K_{n})={con(D)|D is an orientation of K_{n}} and S_{SC}(K_{n})={con(D)|D is a strong orientation of K_{n}}. We show that S_{C}(K_{3})={1,2} and S_{C}(K_{n})={1,3,4,...,n-1} if n >= 4. We also have that S_{SC}(K_{3})={1} and S_{SC}(K_{n})={1,3,4,...,n-2} if n >= 4 . We also show that every triple n, m, k of integers with n >= 5, 3 <= k <= n-2, and n+1 <= m <= n(n-1)/2, there exists a strong connected oriented graph D of order n with |E(D)|=m and con (D)=k.

Differential space time block coding is a technology that combining traditional space time block coding and differential coding. Differential space time block coding could exploit full spatial diversity gain where the channel state information is not known. Each user in CC-CDMA system is assigned a fold of codes which sent via different carriers to reconstruct perfect auto-correlation and cross-correlation function. Complete Complementary codes could offer MAI-free and MI-free operation for DS-spreading. In this thesis we combine differential space time block coding and CC-CDMA, and discuss the character of the system.

In this thesis, we proposed a simple yet novel multicast scheduling scheme for IEEE 802.16e wireless metropolitan area networks. Specifically, we want to solve the problem that how the base station schedules data messages in a multicast superframe such that mobile stations can receive their required multicast data and the total awake time of mobile stations is minimal. We first prove that this problem is NP-complete, and then propose a greedy k-approximation algorithm, named G-EEMS, whose running time is , where n is the total number of multicast data messages and k is the size of MBS (multicast and broadcast service) zone in a frame. Simulation results show that, in terms of energy throughput, G-EEMS significantly outperforms the existing scheme, called SMBC-D.

published_or_final_version / abstract / toc / Mathematics / Master / Master of Philosophy

There is little evidence that Health Technology Assessment (HTA) is much used in dentistry. Dental implant technology is an example of innovative oral health technology. The objectives of this research were to gather the evidence needed for the assessment of overdenture implant treatment so that both patients and dental practitioners can make informed decisions about this technology. These objectives included 1) investigating what types of dental clinicians adopt and provide dental implants 2) determining the effect of the clinicians' experience in the provision of implant supported prostheses and 3) measuring the patients' preference in provision of mandibular 2-implants overdenture technology. / For the first part, a cross-sectional survey was sent to all licensed Canadian Dentists to measure the adoption and provision of implant technology. For the second part, we used the data on the first 140 edentulous elders who were enrolled in a randomized controlled clinical trial to compare the effects of mandibular conventional (CD) and 2-implant overdentures (IOD) on nutrition. The change in patient ratings of satisfaction after treatment, laboratory costs and the number of unscheduled visits were compared. For the last part, edentulous elders (N=36) who were wearing maxillary dentures and either a mandibular conventional denture (CD, n=13) or a two-implant overdenture (IOD, n=23) participated in this study. Participants' preference was measured during a 20-minute interview. / Multivariate regression analysis on the data from the first part of the study shows that the Dentist's gender, province of practice, specialty, and whether they practice alone or in association with other practitioners, are significantly associated with the adoption of implant technology (p&lt;0.05). It is also shown that there was no difference in satisfaction scores for either prosthesis between the groups treated by experienced specialists or new dentists. Furthermore, it is shown that IOD wearers were willing to pay three times more than the current cost of conventional dentures for implant prostheses (p&lt;0.05). / Overall, the results of this study 1) inform decision makers on what types of clinicians provide implant technology and 2) suggest that, with minimal training, all dental clinicians irrespective of their specialty, can provide successful implant overdenture prostheses that edentulous patients are willing to pay for.

It is known that the ring of invariants of any two-row group is Cohen-Macaulay. This result inspired the conjecture that the ring of invariants of any two-row group is a complete intersection. In this thesis, we study this conjecture in the case where the ground field is the prime field $\mathbb{F}_p$. We prove that all Abelian reflection two-row $p$-groups have complete intersection invariant rings. We show that all two-row groups with \textit{non-normal} Sylow $p$-subgroups have polynomial invariant rings. We also show that reflection two-row groups with \textit{normal} reflection Sylow $p$-subgroups have polynomial invariant rings. As an interesting application of a theorem of Nakajima about hypersurface invariant rings, we rework a classical result which says that the invariant rings of subgroups of $\text{SL}(2,\,p)$ are all hypersurfaces. In addition, we obtain a result that characterizes Nakajima $p$-groups in characteristic $p$, namely, if the invariant ring is generated by norms, then the group is a Nakajima $p$-group. / Thesis (Ph.D, Mathematics & Statistics) -- Queen's University, 2009-09-29 15:08:40.705

This Major Degree Project explores the concept of “complete streets” and the framing of an appropriate “complete streets” checklist for historic districts and character neighbourhoods in downtown contexts, attempting to learn especially from the case of Winnipeg’s Warehouse District Neighbourhood. A “complete streets” checklist is considered to include a combination of infrastructure and urban design considerations, such as sidewalks, bike lanes, intersections, transit stops, curb extensions, travel lane widths, and parking needs. It proceeds from the premise that if an individual street or system of streets is ‘complete’, individuals will be more likely to reduce the time spent using automobiles, and increase the time expended on walking, biking, or using other transit alternatives, while making travel on the streets safer and more enjoyable for all users. The MDP examines the current street-related infrastructure and uses within the Warehouse District Neighbourhood of Downtown Winnipeg and discusses the relevance of current or recent City of Winnipeg plans and proposals. Taking the form of a practicum, the research sought to inform and engage local planners, engineers and public officials regarding a “complete streets” approach to their work – primarily in terms of the recommended framing of a complete streets checklist as well as recommendations for future area improvements in the Warehouse District Neighbourhood, demonstrating the usefulness of the checklist.

Given graphs G,H, is it possible to find a matching which, when deleted from G, destroys all copies of H? The answer is obvious for some inputs—notably, when G is a large complete graph the answer is “no”—but in general this can be a very difficult question. In this thesis, we study this decision problem when H is a fixed tree or cycle; our aim is to identify those H for which it can be solved efficiently. The H-transverse matching problem, TM(H) for short, asks whether an input graph admits a matching M such that no subgraph of G − M is isomorphic to H. The main goal of this thesis is the following dichotomy. When H is a triangle or one of a few small-diameter trees, there is a polynomial-time algorithm to find an H-transverse matching if one exists. However, TM(H) is NP-complete when H is any longer cycle or a tree of diameter ≥ 4. In addition, we study the restriction of these problems to structured graph classes. / Graduate