• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1679925
  • 313258
  • 10220
  • 6571
  • 1256
  • 874
  • 182
  • 181
  • 180
  • 176
  • 167
  • 162
  • 139
  • 130
  • 59
  • Tagged with
  • 135137
  • 78193
  • 74608
  • 67095
  • 65175
  • 56160
  • 49350
  • 47978
  • 46082
  • 41584
  • 36519
  • 34968
  • 34468
  • 32389
  • 32068
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
820081

Functional Characterization of the Parl Mitochondrial Proteins in Zebrafish (Danio rerio)

Noble, Sandra A. 30 April 2014 (has links)
The aim of this thesis was the functional characterization of the zebrafish parl (Presenilin-Associated Rhomboid-Like) genes which code for mitochondrial proteins involved in cell survival. A mutation in PARL has been described in Parkinson’s disease patients. I investigated the role of mitochondrial PD-related proteins using a zebrafish parla and parlb deficiency model. I found that the knockdown of both parl genes is lethal. Parla plays a larger role in patterning of the DA neurons in the ventral diencephalon than Parlb. The human PARL rescued the double morphant phenotype, suggesting function conservation between zebrafish and humans. I was able to rescue the mortality and DA neuron mispatterning observed in double morphants with synthetic pink1 mRNA. This suggests that parl genes are epistatic to pink1 in zebrafish. To visualize mitochondria specifically in dopaminergic neurons of live zebrafish, I established a transgenic line Tg(dat:tom20 MLS-mCherry) where regulatory elements of the dopamine transporter (dat) were used to drive expression of a Tom20-mCherry fusion protein that is targeted to the mitochondria. I characterised the expression of Tom20-mCherry to the mitochondria of the majority of DA neuron groups. In addition, I observed a decrease in mCherry fluorescence following MPTP exposure of live fish. The PD-related mutation in PARL is located in a cleavage site of the mammalian protein, which is necessary for the production of the beta peptide; however, this site is predicted to be absent in the zebrafish Parls. To establish the cleavage patterns of the zebrafish Parls and compare them to those of human PARL, I examined the cleavage of Parl-Flag constructs in cultured cells. I detected one band for Parla-Flag and two bands representing Parlb-Flag. The parla and parlb deficiency model along with the characterization of the cleavage patterns of Parl and the Tg(dat:tom20 MLS-mCherry) transgenic line are tools which will help elucidate the role of mitochondrial proteins in PD research.
820082

A Geochemical and Isotopic Investigation of Metasedimentary Rocks from the North Caribou Greenstone Belt, Western Superior Province, Canada

Duff, Jason 30 April 2014 (has links)
The North Caribou Greenstone Belt (NCGB) lies at the core the granitoid-dominant North Caribou Terrane (NCT). Two sedimentary assemblages; the Eyapamikama (ELS) and Zeemal-Heaton Lake (ZHA) form the core of the NCGB. Geochemistry of garnets from the orogenic Au deposit at Musselwhite suggest that the auriferous fluids have a contribution of metamorphic fluids and mineralization consisted of prolonged, multi-stage periods. Chemical zoning suggests changes in the influx of chalcophile and lithophile elements and that Au/sulphide ratios during nucleation were lower relative to later growth events. Zircons from the ELS and ZHA suggest a c. 100 My hiatus in the onset of sedimentation, with the ZHA showing younger, “Timiskaming-type” ages. Age distributions from each assemblage reflect proximal, igneous sources. Nd isotopic compositions of the ZHA suggest a mixture of ancient and contemporaneous sources which are similar to external TTG rocks. Deplete mantle model ages of the ZHA rocks indicate a Mesoarchean inheritance.
820083

Examining Thinking Skills in the Context of Large-scale Assessments Using a Validation Approach

Hachey, Krystal 30 April 2014 (has links)
Large Scale Assessments (LSAs) of student achievement in education serve a variety of purposes, such as comparing educational programs, providing accountability measures, and assessing achievement on a broad range of curriculum standards. In addition to measuring content-related processes such as mathematics or reading, LSAs also focus on thinking-related skills such as lower level thinking (e.g., understanding concepts) and problem solving. The purpose of the current study was to deconstruct and clarify the mechanisms that make up an LSA, including thinking skills and assessment perspectives, from a validation approach based on the work by Messick (1995) and Kane (1990). Therefore, when examining the design and student data of two LSAs in reading, (a) what common thinking skills are assessed? and (b) what are the LSAs’ underlying assessment perspectives? Content analyses were carried out on two LSAs that purported to assess thinking skills in reading: the Pan-Canadian Assessment Program (PCAP) and the Educational Quality and Accountability Office (EQAO). As the two LSAs evaluated reading, the link between reading and thinking was also addressed. Conceptual models were developed and used to examine the assessment framework, test booklets, and scoring guide of the two assessments. In addition, a nonlinear factor analysis was conducted on the EQAO item-level data from the test booklets to examine the dimensionality of the LSA. The most prominent thinking skill referenced after qualitatively analyzing the assessment frameworks, test booklets, and scoring guides was critical thinking, while results from the quantitative analysis revealed that two factors best represented the item-level EQAO data. Overall, the tools provided in the current study can help inform both researchers and practitioners about the interaction between the assessment approach and related thinking skills.
820084

Video Streaming in Vehicular Ad Hoc Networks: Challenges, Protocols and The Use of Redundancy

Rezende, Cristiano 30 April 2014 (has links)
Vehicular Ad Hoc Networks (VANETs) are no longer a futuristic promise but rather an attainable technology. Vehicles are already equipped with a variety of computational devices that control or assist drivers in many tasks such as localization, safely breaking, parking and passengers entertainment. The majority of services envisioned for VANETs either require the provision of multimedia support or have it as an extremely beneficial additional feature. In particular, video streaming capabilities over VANETs are crucial to the development of interesting and valuable services. However,VANETs’ highly dynamic topology poses as a demanding challenge to the fulfillment of video streaming’s stringent requirements. The main goal on this thesis is the development of feasible solutions that support the streaming of video content over VANETs. Initially, the main issues of VANETs are explained through both a discussion of its characteristics and the results of some preliminary conclusions. Based on this understanding of VANETs’ peculiarities, three distinguishing solutions are designed REACT-DIS, REDEC and VIRTUS; the two first for video dissemination and the later for video unicast. These solutions offer a great advancement towards the provision of video streaming capabilities but packet loss is still an issue at high data rates. In order to improve the delivery ratios reached by the previous solutions, redundancy is used as an error correction mechanism. The use of redundancy is ideal for VANETs in handling packet loss as they do not require any interaction between source and receivers nodes. Sophisticated coding techniques were used for an efficient use of the increase on entropy of the information sent by the source node. It was also evaluated the selective use of redundancy solely on packets carrying the crucial information of I-frames. Although this selective approach obtained lower overall delivery ratios than when redundancy is used for all packets, the video quality obtained similar improvements under a much lower cost. The evaluation on the use of redundancy has considered the impact on the rate by which unique video content is received at end-users which is fundamental to understand the resolution of videos that can be displayed. This thesis provides several contributions as it advances the knowledge in the peculiarities of VANETs, solutions for video streaming over VANETs and the use of redundancy as an error correction mechanism for video streaming over VANETs.
820085

Network Traffic Control Based on Modern Control Techniques: Fuzzy Logic and Network Utility Maximization

Liu, Jungang 30 April 2014 (has links)
This thesis presents two modern control methods to address the Internet traffic congestion control issues. They are based on a distributed traffic management framework for the fast-growing Internet traffic in which routers are deployed with intelligent or optimal data rate controllers to tackle the traffic mass. The first one is called the IntelRate (Intelligent Rate) controller using the fuzzy logic theory. Unlike other explicit traffic control protocols that have to estimate network parameters (e.g., link latency, bottleneck bandwidth, packet loss rate, or the number of flows), our fuzzy-logic-based explicit controller can measure the router queue size directly. Hence it avoids various potential performance problems arising from parameter estimations while reducing much computation and memory consumption in the routers. The communication QoS (Quality of Service) is assured by the good performances of our scheme such as max-min fairness, low queueing delay and good robustness to network dynamics. Using the Lyapunov’s Direct Method, this controller is proved to be globally asymptotically stable. The other one is called the OFEX (Optimal and Fully EXplicit) controller using convex optimization. This new scheme is able to provide not only optimal bandwidth allocation but also fully explicit congestion signal to sources. It uses the congestion signal from the most congested link, instead of the cumulative signal from a flow path. In this way, it overcomes the drawback of the relatively explicit controllers that bias the multi-bottlenecked users, and significantly improves their convergence speed and throughput performance. Furthermore, the OFEX controller design considers a dynamic model by proposing a remedial measure against the unpredictable bandwidth changes in contention-based multi-access networks (such as shared Ethernet or IEEE 802.11). When compared with the former works/controllers, such a remedy also effectively reduces the instantaneous queue size in a router, and thus significantly improving the queueing delay and packet loss performance. Finally, the applications of these two controllers on wireless local area networks have been investigated. Their design guidelines/limits are also provided based on our experiences.
820086

Lotus Pond, Bicultural Ripples: The Psychological Orientations of Korean-Canadian Practitioners of Buddhism

Choi, Glen S. 30 April 2014 (has links)
This dissertation examines whether Buddhist beliefs and practices serve to reinforce and/or promote a Korean and/or Canadian cultural prism for next-generation Korean Buddhist practitioners in Toronto, Canada. I define Korean and Canadian cultural prisms based on the cross-cultural psychological framework of Individualism-Relational Collectivism (I-RC) and Analytical-Holistic (A-H) cognition. The aim of my research is to problematize culture in the construction of religious meaning and behaviour for relatively bicultural individuals. My research question can thus be summarized as follows: How is religious meaning and behaviour culturally constructed by next-generation Korean Buddhist practitioners in Canada? What role do individual cultural orientations and the different Buddhist cultural traditions play in this cultural construction and how does Buddhism compare to the other religions (namely Protestantism) practiced by younger-generation Korean-Canadians in this regard? By answering these questions, I ultimately hope to show whether the meaning system of Korean culture is preserved through religion among the younger generation of Korean Buddhist practitioners. I hypothesize that, due to the relatively non-authoritarian nature of Buddhism, the light of Buddhist beliefs and practices will predominantly be refracted through the a priori cultural prism of the individual in question, and the role of Buddhist doctrine and institutions in promoting a particular orientation (individualistic/relationally collectivistic and analytic/holistic) will be minimal and subordinate to the individual. The particular cultural orientation of this prism will, in turn, be dependent upon individual levels of monoculturalism (Korean or Canadian) or biculturalism (Korean and Canadian). In this way, Buddhism may serve to both preserve and undermine the Korean cultural meaning system. By comparison, I hypothesize that the relatively authoritarian nature of (Protestant) Christianity will likely encourage younger-generation Korean Christians to relate to their religion in a predominantly uniform way, regardless of the individual’s cultural orientation.
820087

CO2 Capture from Dilute Sources via Lime-Based Sorbents

Samari, Mohammad 30 April 2014 (has links)
Direct capture of CO2 from ambient air is a developing technology, which is capable of removing CO2 directly from the atmosphere. Moreover, this technology is independent from sources of CO2 emissions. Hence, it can be set up at locations where pure stream of CO2 is needed such as in enhanced oil recovery. In this research, the performance of pelletized and natural limestone for CO2 capture from air in a fixed bed is studied. To compare the performance of sorbents for air capture, the effects of particle type (natural limestone and pelletized limestone), particle size (250-425 µm and 425-600 µm), gas flowrate (0.5 L/min and 1 L/min), and relative humidity, on the breakthrough time, breakthrough shape, and the global reaction rate are examined. Moreover, carbonation decay of sorbents over series of capture and regeneration cycles is studied. If the inlet stream (air) is humidified at 50% relative humidity, but the lime sorbents are not pre-hydrated, an axially non-uniform carbonated bed results. This phenomenon is due to the partial carbonation of sorbents at the first layers of the bed. While there is a competition between CO2 and water to react with CaO, partial carbonation reaction on the surface of the sorbents not only prevents further hydration, but also decreases the reaction rate at the surface. However, in comparison with a dry system where relative humidity was negligible and sorbents were not pre-hydrated, the observed carbonation conversion was higher. The best results were seen from experiments with pre-hydrated sorbents and humidified inlet stream. The smaller sorbent particles had a better performance (sharper breakthrough curve and longer breakthrough time) due to their greater surface area. A gas-solid reaction model was fitted to the breakthrough curves. Since at the beginning of carbonation there is no resistance of the product layer, it can be assumed that the process is reaction controlled. While after formation of the product layer (CaCO3), it becomes diffusion controlled. Results from fitted data also confirmed these conclusions. Moreover, each of sorbent went through 9 cycles and after each cycle the carbonation conversion of the sorbents was measured by TGA and the surface area by BET.
820088

Distributed Algorithms for Networks Formation in a Scalable Internet of Things

Jedda, Ahmed 30 April 2014 (has links)
The Internet of Things (IoT) is a vision that aims at inter-connecting every physical identifiable object (or, a thing) via a global networking infrastructure (e.g., the legacy Internet). Several architectures are proposed to realize this vision; many of which agree that the IoT shall be considered as a global network of networks. These networks are used to manage wireless sensors, Radio Frequency IDentification (RFID) tags, RFID readers and other types of electronic devices and integrate them into the IoT. A major requirement of the IoT architectures is scalability, which is the capability of delivering high performance even if the input size (e.g., number of the IoT objects) is large. This thesis studies and proposes solutions to meet this requirement, and specifically focuses on the scalability issues found in the networks of the IoT. The thesis proposes several network formation algorithms to achieve these objectives, where a network formation algorithm is an algorithm that, if applied to a certain network, optimizes it to perform its tasks in a more efficient manner by virtually deleting some of its nodes and/or edges. The thesis focuses on three types of networks found in the IoT: 1) RFID readers coverage networks; whose main task is to cover (i.e., identify, monitor, track, sense) IoT objects located in a given area, 2) readers inter-communications networks; whose main task is to guarantee that their nodes are able to inter-communicate with each other and hence use their resources more efficiently (the thesis specifically considers inter-communication networks of readers using Bluetooth for communications), and 3) Object Name Systems (ONS) which are networks of several inter-connected database servers (i.e., distributed database) whose main task is to resolve an object identifier into an Internet address to enable inter-communication via the Internet. These networks are chosen for several reasons. For example, the technologies and concepts found in these networks are among the major enablers of the IoT. Furthermore, these networks solve tasks that are central to any IoT architecture. Particularly, the thesis a) studies the data and readers redundancy problem found in RFID readers coverage networks and introduces decentralized RFID coverage and readers collisions avoidance algorithms to solve it, b) contributes to the problem of forming multihop inter-communications networks of Bluetooth-equipped readers by proposing decentralized time-efficient Bluetooth Scatternet Formation algorithms, and c) introduces a geographic-aware ONS architecture based on Peer-To-Peer (P2P) computing to overcome weaknesses found in existing ONS architectures.
820089

A Quality Guaranteed Video Dissemination Protocol over Urban Vehicular Ad Hoc Networks

Li, Yang 30 April 2014 (has links)
Video dissemination over Vehicular Ad Hoc Networks (VANETs) is an attractive technology which supports many novel applications. Hence, the merit of this thesis has twofold. Firstly, we evaluate and compare three routing techniques and two error resilience techniques. We select a sender-based routing technique called SUV and compare it with the other two selected receiver-based routing techniques named REACT-DIS and CDS. The results, more specifically, show that the receiver-based solutions outperform the sender-based solution. In addition, only CDS method fulfils the general quality requirements as it is the best that reduces redundancy packets and covers the whole topology. The results also indicate that the video coding scheme, Interleaving, can fix the multiple consecutive packet losses and guarantee reliable video qualities over VANETs. Network Coding, however, fails to provide satisfactory video quality for urban scenarios. This study next combines the selected receiver based routing techniques and the two error resilience techniques. We find the best combination is Interleaving over CDS. Secondly, we design a quality guaranteed video dissemination protocol for urban VANETs scenarios. Based on our comparison result, our protocol selects the CDS and Interleaving as the routing and error resilient techniques. To fix the single packet loses caused by the topology’s intermittent disconnection and collisions, we propose a store-carry-broadcast scheme for the nodes to re-transmit the local buffer saved packets. The results, when compared to the selected techniques and combinations, show that our proposed protocol is the most efficient one in terms of packet delivery, delay, overhead and video quality.
820090

Translating the True North: Exploring Representations of Canada Around the 2010 G8 and G20 Summits

Harms, Charissa 30 April 2014 (has links)
A country’s international reputation has profound implications for its citizens; given that national image or reputation is built and circulated using language on a global scale, translation is necessarily involved. This project draws on bilingual corpora of government and media texts to examine how Canada was framed in the discourses and narratives in circulation in its two official languages at the time of the 2010 G8 and G20 Summits, using concepts and techniques from Critical Discourse Analysis, narrative theory, and corpus linguistics. Examining some aspects of language in use such as collocation, semantic relations, and metaphor, several of the ways in which Canada was framed in the two contexts and languages were compared. The project concludes that discourses and narratives may differ between sources and languages, thereby highlighting the importance of recognizing the impact of translation on the variety of national representations within discourses and narratives.

Page generated in 1.2193 seconds