International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / The design of a protocol for a satellite cluster link establishment and management that accounts for link corruption, node failures, and node re-establishment is presented in this paper. This protocol will need to manage the traffic flow between nodes in the satellite cluster, adjust routing tables due to node motion, allow for sub-networks in the cluster, and similar activities. This protocol development is in its initial stages and we will describe how we use the LabVIEW Sate Diagram tool kit to generate the code to design a state machine representing the protocol for the establishment of inter-satellite communications links.

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that affects the feet in up to 90% of patients, and can result in bone erosions. Little is known about disease activity at the metatarsophalangeal joints (MTPJs). Magnetic resonance imaging is used to visualize erosions, but does not provide quantification. Quantitative computed tomography (QCT) allows for differentiation between bone layers and quantifies volumetric bone mineral density (vBMD). We used a peripheral QCT (pQCT) scanner in MTPJs 2-5 in RA patients to determine reliability of a pQCT protocol, and then we determined the variability in vBMD between RA patients and controls. Patients (n=25) diagnosed with RA (2010 ACR criteria) were recruited from an academic Rheumatology clinic. Controls (n=27) were also recruited and matched for sex, age and ethnicity. Baseline MR data demonstrated that 80%, 64%, 40% and 20% of patients had erosions at MTPJs 2-5, respectively. One year later, MTPJs 2-5 were scanned using pQCT (XCT 2000); 2 transaxial slices were acquired per joint. A trained pQCT operator acquired 2 scans per participant with repositioning. Test-retest, intra- and inter-rater reliability were assessed blindly for total and cortical subcortical densities (mg/cm3). Reliability was reported as root mean square coefficients of variation (%RMSCV) and RMS standard deviation (RMSSD). The mean (SD) age and disease duration were 57.8 (10.2) years and 5.0 (0.9) years, respectively. Test-retest reliability was better for MTPJs 2 and 3, than MTPJs 4 and 5. Inter- and intra-rater reliability demonstrated high reproducibility. Total and cortical subcortical vBMD appeared lower in RA patients than controls. We have reliably determined vBMD using pQCT in MTPJs 2 and 3 in RA patients. The lower vBMD in MTPJ 3 suggests that RA patients may have true erosions at this joint. This research is in the early phases, but we hope to explore the correspondence between pQCT and other RA assessment tools. / Thesis / Master of Science (MSc) / Rheumatoid arthritis (RA) affects joints in the hands and feet. The bones of these joints are affected by periarticular bone loss leading to bone erosions. Magnetic resonance imaging (MRI) and X-ray are used to visualize erosions. Since erosions are characterized by a decrease in bone mineral density (BMD) leading to holes in the bone, we tested the reliability of a peripheral quantitative computed tomography (pQCT) scanner, to measure volumetric BMD (vBMD) in 25 RA patients and compared vBMD to healthy controls. The vBMD measures appeared lower in RA patients than healthy individuals in some joints. As well, there was agreement between bone erosions detected by MRI and reduced vBMD measured by pQCT. Although we could not monitor the change over time, we are hopeful that this scanner will be able to better characterize RA disease activity, with vBMD as a surrogate marker for erosion presence.