published_or_final_version / Dentistry / Master / Master of Orthodontics

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

In this talk, directional frames, known as curvelets, are used to recover seismic data and images from noisy and incomplete data. Sparsity and invariance properties of curvelets are exploited to formulate the recovery by a `1-norm promoting program. It is shown that our data recovery approach is closely linked to the recent theory of “compressive sensing” and can be seen as a first step towards a nonlinear sampling theory for wavefields. The second problem that will be discussed concerns the recovery of the amplitudes of seismic images in clutter. There, the invariance of curvelets is used to approximately invert the Gramm operator of seismic imaging. In the high-frequency limit, this Gramm matrix corresponds to a pseudo-differential operator, which is near diagonal in the curvelet domain.

The basic principle of tissue engineering is the combination of appropriate cells with biomaterials under conditions that promote and lead to tissue formation. A tissue engineering scaffold is a material that supports cells for their growth, proliferation, and differentiation in the absence of native extracellular matrix (ECM). The ECM was originally thought to provide primarily a mechanical support for the cells, but through receptors on the surface of cells, the ECM takes part in promoting cell adhesion, migration, growth, differentiation, and apoptosis. Ideally, a tissue engineered scaffold should mimic both the form and function of native ECM. Additionally, like any other biomaterial for implantation, a tissue engineered scaffold should be biocompatible and not initiate tissue reactions or immune responses. This work focuses on the evaluation of the biocompatibility of novel alloy-based materials for orthopedic applications. In addition, in the context of bone regeneration, it examines the influence of select native ECM constituents on mesenchymal stem cell (MSC) osteogenic differentiation in 3-D contexts. On the other hand, given the crucial role of vasculogenesis in cell nutrition in the scaffolds, ECM mimics found to support osteogenesis were further evaluated for endothelial cell adhesion and migration. For the hydrogel systems presented in this manuscript, poly(ethylene glycol) diacrylate (PEGDA) networks were selected as the base scaffold due to the broad tunability of their mechanical properties and their previous use in bone regeneration applications. In addition, pure PEGDA hydrogels do not intrinsically promote cell adhesion. Thus, cell interactions with PEGDA gels are initially isolated to the interactions supported by the proteins tethered to the scaffold. This work attempts to contribute to the development of novel materials that provide biocompatibility and enhanced versatility in orthopedic applications. Moreover, in the context of bone regeneration, the use of selective ECM biomolecules in hybrid hydrogel scaffolds will aid in the understanding of MSC osteogenic responses to specific ECM constituents. Additionally, incorporation of ECM mimics that support both osteogenesis and vasculogenesis will provide a more controlled platform which will serve as a foundation for the fabrication of more efficient vascularized bone constructs.

Matrix Sentence Tests consist of syntactically fixed but semantically unpredictable sentences each composed of 5 words (name, verb, quantity, adjective, object). Test sentences are generated by choosing 1 of 10 alternatives for each word to form sentences such as

Today's home network usually involves connecting multiple PCs and peripheral devices, such as printers and scanners, together in a network. This provides the benefit of allowing the PCs in the network to share Internet access and other resources. However, it is expected in the future, the home area network (HAN) will grow and extend to other home devices such as home entertainment systems (including digital TV, hi-fi stereo, etc.), appliances, webcam, security alarm system, etc. Connecting other home devices to a HAN provides users with many benefits not available in today's home networks. For example, home devices capable of connecting to the future HAN are able to share the content downloaded from broadband access anywhere in the home. Users can also have remote access and control of their home devices. To extend the home area network to all these different home devices, however, means that the traffic between the ISP and future HAN will be very different from the traffic generated by today’s home network. In today's home network, which consists mainly of multiple PCs, a best-effort approach is able to satisfy the need, since most of the traffic generated by PCs is not real-time in nature. However, in future HANs, it is anticipated that traffic generated from home devices requiring real-time applications such as multimedia entertainment systems, teleconferencing, etc. will occupy a large proportion of the traffic between the ISP and future HANs. In addition, given the variety of home devices that could potentially be added to future HANs, the amount and variety of traffic between the ISP and a future HAN will certainly be very different from today's home network that is dominated by Internet/data traffic. To allow HAN users of these real-time applications and various types of home devices to continue enjoying seamless experiences in using their home devices without noticing significant delays or unnecessary interruptions, it is important for the ISP to be able to effectively manage the channel to the home so that it can provide sufficient bandwidth to ensure high QoS for home applications. The aim of this thesis is to understand the types of traffic that will be expected and to develop an analytical model that will represent the traffic behaviour between the ISP and future HANs to understand how to manage the channel to provide high QoS. In this thesis, we use the continuous-time PH/M/n/m preemptive priority queue to model the traffic behaviour between the ISP and a future HAN. Three classes of traffic are defined in this model: real-time, interactive, and unclassified. Each of these three traffic classes receives a unique priority level. From the model one can approximate the amount of bandwidth required to be allocated for each traffic class for each household so that the total bandwidth required is minimized while the QoS requirements (delay and blocking probability) of the traffic generated by the home devices are met. Thus this model could potentially be used as a network planning tool for ISPs to estimate how much bandwidth they need to provide per household for homes that use home area network. Alternatively, it could also be used to estimate what quality of service (e.g. what is the mean delay and blocking probability expected) given a certain amount of bandwidth per household.

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