Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2006. / Härtill 4 uppsatser.

Hannover, University, Diss., 2005.

The project is an orbital design study of a proposed CubeSat at Mississippi State University. The launch date is not specified. As for the mission, it is defined as forest fire detection. CubeSats are small satellites that are 10 x 10 x 10 cm in dimension and has a mass no more than 1 kg. They are currently used in different applications in many countries as an easy access to space. The analyses of this project have been carried out using a commercial software package, System Tool Kit (STK), developed by Analytical Graphics, Incorporated. This software provides a tool for performing simulations required for determining the orbit or the trajectory for satellites. In addition, a perturbation orbital study has been conducted and different propagators have been tested.

Orbital pseudotumor, also known as idiopathic orbital inflammatory disease (IOID), is an idiopathic inflammatory process within the orbit. The potential for permanent visual impairment makes this disease important to diagnose and treat. While oral corticosteroids are the mainstay of therapy, they can have significant toxicity when used for long periods of time. We present a case of IOID that was successfully treated with leflunomide after methotrexate was discontinued for toxicity-related issues. To our knowledge, use of leflunomide for this condition has not previously been reported in the literature.

No description available.

No description available.

ABSTRACT A novel locally manufactured and developed porous hydroxyapatite orbital implant has been investigated and found to be as safe as commercially available implants. Objective To describe and analyze the results of twenty orbital implants implanted into patients in one arm of a multicentre trial. Methods A porous hydroxyapatite orbital implant with a smooth cap was developed and implanted into twenty patients. These patients were followed up for a period of four months. Patients were examined for signs of infection or extrusion of the implants. The amount of post-operative pain, chemosis, granuloma formation and vascularity was also assessed. Results None of the twenty patients had any signs of extrusion or infection at the termination of the study. There was very little pain or chemosis noted and no granuloma formation. Conclusion The locally developed implants were safe in anophthalmic eyes when reviewed after a four month follow-up period.

OBJECTIVE: To determine risk factors and examination findings that are predictive of orbital fractures in pediatric patients, in the hope of using the findings to develop a rule for when to obtain a Computerized Tomography Scan (CT). Additionally, we will examine the treatments underwent by patients with confirmed orbital fractures. METHODS: A retrospective cohort study was conducted on patients below the age of 22 who were seen in the Emergency Department (ED) at Boston Children's Hospital (BCH) between January 2009 and May 2013, and underwent Computerized Tomography Scan (CT) for evaluation of orbital fracture. 326 cases were selected for inclusion in analysis. Electronic medical records (EMR) of cases were reviewed and data was collected about mechanism of injury, symptoms, physical exam (PE) findings, diagnosis of orbital fracture, and treatment. Data collected was analyzed using SPSS Statistical Software v.21. Frequency of variables was determined, and chi-square analysis was performed comparing frequencies for patients with orbital fractures to patients without orbital fractures. RESULTS: Of the 326 cases undergoing CT, 133 (40.8%) had radiographic evidence of an orbital fracture. Nausea/vomiting, orbital tenderness, orbital swelling, orbital ecchymosis, and limitation of extraocular movement (EOM) were all identified as statistically significant clinical indicators of orbital fractures. 22 (16.5%) of patients with confirmed orbital fractures underwent surgery, with an average time to surgery of 4.5 days. CONCLUSION: We found that 16.5% of cases with orbital fractures, and only 6.7% of all cases, underwent surgery. We have identified 5 factors that can be used for the development of an evidence-based algorithm for determining when to obtain a CT to rule out an orbital fracture in a pediatric population. We believe that we can use this to improve the evaluation of orbital fractures ED, which in turn will improve the utilization of ED resources, and reduce the exposure of pediatric patients to the risks associated with CT.

We study the electronic band structure of no-common-atom InAs-GaSb superlattice within a nearest-neighbor bond-orbital model. The effect of interfacial asymmetry is also taken into account. This model can reproduce fairly accurate bulk band structures near the center of the Brillouin zone. We find that interfacial asymmetry, which is first included in bond-orbital model, can yield spin splitting. We also find that a negative indirect band gap appears for long period superlattice, due to interfacial asymmetry and band anisotropy of the heavy hole band in GaSb material. This indicates that the semiconductor-semimetal transition, which occurs when the period d reach a critical value dC, does exist in InAs-GaSb superlattice. In our calculation, the critical period dC is about 150 Å.

This dissertation develops a methodology for automated trajectory control of a spacecraft about a non-maneuvering target. The methodology utilizes relative orbital elements (ROEs), combined with guidance laws based upon artificial potential functions (APFs), to perform automated trajectory planning and maneuver design. The investigation provides a definitive reference on the definition and use of ROEs for relative proximity operations. The detailed derivation of ROEs is provided, along with transformations between ROEs and relative Cartesian state elements, characteristics of unforced motion in terms of ROEs, and the effect of impulsive maneuvers on ROEs. Operationally-useful guidance algorithms utilizing ROEs are developed and demonstrated. These ROE-based algorithms for rendezvous, circumnavigation and station-keeping provide a toolkit for relative proximity operations mission planning. A new approach for APF formulation using ROEs as the target variables is developed. While previous approaches allowed targeting of a specified relative position, the present approach allows the targeting of relative orbit geometries. The approach capitalizes upon the orbital dynamics represented through the ROEs, and retains the computational simplicity offered by the APFs. Formulations for the APF targeting of individual ROEs, as well as simultaneous targeting of a set of ROEs, are established. An approach for combining ROE targeting using APFs with obstacle avoidance is presented. The trajectory guidance algorithm performance is evaluated using a flight-like guidance, navigation and control simulation environment, including orbital perturbations. Algorithm performance is established through a set of operationally relevant scenarios. The guidance algorithms are shown to be capable of correcting for environmental disturbances, while meeting the targeted relative orbits in an automated fashion.