No description available.

Satellite cells (SCs) are muscle stem cells that stay in a metabolically and mitotically quiescent state in adult skeletal muscle until activated. In mammals, SCs are activated and enter into the cell cycle for growth and regeneration. The mechanism initiating SC activation in vivo and in vitro, mediated by nitric oxide (NO) and hepatocyte growth factor (HGF) is described in the mouse model, but not in other species. Here, we assessed SC activation by counting bromodeoxyuridine (BrdU)-immuno-positive cells, and found that SC activation in zebrafish single muscle-fibre cultures is also NO and HGF dependent, peaking at 1 mM isosorbide dinitrate (ISDN, an NO donor drug) and 10 ng/mL HGF respectively, using dose-response experiments. Moreover, HGF signalling via the c-Met receptor is involved in the SC activation pathway and is considerably affected by temperature (i.e., 21 °C). Overall, understanding NO-HGF-c-Met signalling in SC activation gives new insights on fish muscle growth and conservation of regulatory pathways between species.

The on-going calibration and validation of visible satellite imagery remains a core activity of the scientific community in pursuit of high quality data characterising the oceanic chlorophyll field, providing input to models assessing primary productivity and the potential role of the oceans in climatic regulation. This work serves to examine the operational characteristics of semi-analytical algorithms that are designed to derive key optical properties from space born observations of ocean colour. The collection of water samples contemporaneously with precision profiled radiometry conforming to similar spectral bands to those of the NASA Sea Viewing Wide Field of view Sensor (SeaWiFS) was planned and executed, with appropriate field sampling techniques developed in accordance with the SeaWiFS Ocean Optics protocols (Mueller and Austin, 1995). Data were collected during extensive fieldwork sampling at a near coastal survey site and during two deep Atlantic research programmes. Historical and recently developed algorithms designed to retrieve the diffuse attenuation coefficient at 490nm and chlorophyll-a pigment concentrations from upwelling radiances were applied to the optical data, to compare the mathematically retrieved in-water properties with the values measured in-situ. The radiometric data were then used to generate general and local algorithm modifications to assess possible differences in the mathematically retrieved values. Statistical analyses of the errors in mathematical retrieval of in-water properties identified stmctured variability resulting from the empirical approach to algorithm generation, supporting the point of view that locally constrained algorithms provide a method of achieving significantly improved results. The problems associated with the derivation of semi-analytical algorithms are then discussed and errors analysed. The new algorithms generated here are found to compare well with their source data and with work by other investigators. Systematic variability was found within the data sets and the affect this has on the determinations is discussed. It is suggested that data users be afforded details of the equations employed in the production of readily available remote sensing products, placing them in a position where they are better able to assess the data in the context of their work.

No description available.

CanX-4/-5 is a formation flying technology demonstration mission that shall demonstrate sub-meter formation tracking control. The key to this precision control is carrier phase differential GPS state estimation, which enables centimeter-level relative state estimation. In this thesis, the formation flying controller design is reviewed in detail, and an innovative closed-loop formation reconfiguration strategy is presented. In addition, the designs of both coarse- and fine-mode relative state estimators are presented. Formation flying simulations demonstrate the efficacy of the proposed control and coarse estimation. Furthermore, hardware tests are performed to test the computational efficiency of the control algorithms and to validate the fine-mode relative navigation filter.

CanX-4/-5 is a formation flying technology demonstration mission that shall demonstrate sub-meter formation tracking control. The key to this precision control is carrier phase differential GPS state estimation, which enables centimeter-level relative state estimation. In this thesis, the formation flying controller design is reviewed in detail, and an innovative closed-loop formation reconfiguration strategy is presented. In addition, the designs of both coarse- and fine-mode relative state estimators are presented. Formation flying simulations demonstrate the efficacy of the proposed control and coarse estimation. Furthermore, hardware tests are performed to test the computational efficiency of the control algorithms and to validate the fine-mode relative navigation filter.

Quantum key distribution (QKD), a novel cryptographic technique for secure distribution of secret keys between two parties, is the first successful quantum technology to emerge from quantum information science. The security of QKD is guaranteed by fundamental properties of quantum mechanical systems, unlike public-key cryptography whose security depends on difficult to solve mathematical problems such as factoring. Current terrestrial quantum links are limited to about 250 km. However, QKD could soon be deployed on a global scale over free-space links to an orbiting satellite used as a trusted node. Envisioning a photonic uplink to a quantum receiver positioned on a low Earth orbit satellite, the Canadian Quantum Encryption and Science Satellite (QEYSSat) is a collaborative project involving Canadian universities, the Canadian Space Agency (CSA) and industry partners. This thesis presents some of the research conducted towards feasibility studies of the QEYSSat mission. One of the main goals of this research is to develop technologies for data acquisition and processing required for a satellite-based QKD system. A working testbed system helps to establish firmly grounded estimates of the overall complexity, the computing resources necessary, and the bandwidth requirements of the classical communication channel. It can also serve as a good foundation for the design and development of a future payload computer onboard QEYSSat. This thesis describes the design and implementation of a QKD post-processing system which aims to minimize the computing requirements at one side of the link, unlike most traditional implementations which assume symmetric computing resources at each end. The post-processing software features precise coincidence analysis, error correction based on low-density parity-check codes, privacy amplification employing Toeplitz hash functions, and a procedure for automated polarization alignment. The system's hardware and software components integrate fully with a quantum optical apparatus used to demonstrate the feasibility of QKD with a satellite uplink. Detailed computing resource requirements and QKD results from the operation of the entire system at high-loss regimes are presented here.

This thesis focuses on the development of the Direct Broadcasting Satellite in Japan under its Kodo Johoka Shakai (Highly Advanced Information Society) policy. The field of new media policies is relatively new but very important in communications studies. The development of new media technologies changes into existing media systems, and profoundly influences economies which are increasingly dependent upon information services. / Japan's case is particularly interesting. Relatively little is known about its DBS policy compared to other industrialized countries, even though Japan has already begun to operate DBS under its own version of the "information society", the Kodo Johoka Shakai (Highly Advanced Information Society). The formulation of DBS policy is related to many factors, including space development, research and development, broadcasting, international telecommunications regulations and economic competition both in international and domestic markets. In order to take these factors into consideration, an historical approach and institutional analysis are used in this thesis.

Graduation date: 1997

Quantum key distribution (QKD), a novel cryptographic technique for secure distribution of secret keys between two parties, is the first successful quantum technology to emerge from quantum information science. The security of QKD is guaranteed by fundamental properties of quantum mechanical systems, unlike public-key cryptography whose security depends on difficult to solve mathematical problems such as factoring. Current terrestrial quantum links are limited to about 250 km. However, QKD could soon be deployed on a global scale over free-space links to an orbiting satellite used as a trusted node. Envisioning a photonic uplink to a quantum receiver positioned on a low Earth orbit satellite, the Canadian Quantum Encryption and Science Satellite (QEYSSat) is a collaborative project involving Canadian universities, the Canadian Space Agency (CSA) and industry partners. This thesis presents some of the research conducted towards feasibility studies of the QEYSSat mission. One of the main goals of this research is to develop technologies for data acquisition and processing required for a satellite-based QKD system. A working testbed system helps to establish firmly grounded estimates of the overall complexity, the computing resources necessary, and the bandwidth requirements of the classical communication channel. It can also serve as a good foundation for the design and development of a future payload computer onboard QEYSSat. This thesis describes the design and implementation of a QKD post-processing system which aims to minimize the computing requirements at one side of the link, unlike most traditional implementations which assume symmetric computing resources at each end. The post-processing software features precise coincidence analysis, error correction based on low-density parity-check codes, privacy amplification employing Toeplitz hash functions, and a procedure for automated polarization alignment. The system's hardware and software components integrate fully with a quantum optical apparatus used to demonstrate the feasibility of QKD with a satellite uplink. Detailed computing resource requirements and QKD results from the operation of the entire system at high-loss regimes are presented here.