Multi-scale data storage schemes for spatial information systems

This thesis documents a research project that has led to the design and prototype implementation of several data storage schemes suited to the efficient multi-scale representation of integrated spatial data. Spatial information systems will benefit from having data models which allow for data to be viewed and analysed at various levels of detail, while the integration of data from different sources will lead to a more accurate representation of reality. The work has addressed two specific problems. The first concerns the design of an integrated multi-scale data model suited for use within Geographical Information Systems. This has led to the development of two data models, each of which allow for the integration of terrain data and topographic data at multiple levels of detail. The models are based on a combination of adapted versions of three previous data structures, namely, the constrained Delaunay pyramid, the line generalisation tree and the fixed grid. The second specific problem addressed in this thesis has been the development of an integrated multi-scale 3-D geological data model, for use within a Geoscientific Information System. This has resulted in a data storage scheme which enables the integration of terrain data, geological outcrop data and borehole data at various levels of detail. The thesis also presents details of prototype database implementations of each of the new data storage schemes. These implementations have served to demonstrate the feasibility and benefits of an integrated multi-scale approach. The research has also brought to light some areas that will need further research before fully functional systems are produced. The final chapter contains, in addition to conclusions made as a result of the research to date, a summary of some of these areas that require future work

Interactive 3-D Visualization: A tool for seafloor navigation, exploration, and engineering

Recent years have seen remarkable advances in sonar technology, positioning capabilities, and computer processing power that have revolutionized the way we image the seafloor. The massive amounts of data produced by these systems present many challenges but also offer tremendous opportunities in terms of visualization and analysis. We have developed a suite of interactive 3-D visualization and exploration tools specifically designed to facilitate the interpretation and analysis of very large (10\u27s to 100\u27s of megabytes), complex, multi-component spatial data sets. If properly georeferenced and treated, these complex data sets can be presented in a natural and intuitive manner that allows the integration of multiple components each at their inherent level of resolution and without compromising the quantitative nature of the data. Artificial sun-illumination, shading, and 3-D rendering can be used with digital bathymetric data (DTM\u27s) to form natural looking and easily interpretable, yet quantitative, landscapes. Color can be used to represent depth or other parameters (like backscatter or sediment properties) which can be draped over the DTM, or high resolution imagery can be texture mapped on bathymetric data. When combined with interactive analytical tools, this environment has facilitated the use of multibeam sonar and other data sets in a range of geologic, environmental, fisheries, and engineering applications

Frequency of cannabis and illicit opioid use among people who use drugs and report chronic pain: A longitudinal analysis.

BACKGROUND:Ecological research suggests that increased access to cannabis may facilitate reductions in opioid use and harms, and medical cannabis patients describe the substitution of opioids with cannabis for pain management. However, there is a lack of research using individual-level data to explore this question. We aimed to investigate the longitudinal association between frequency of cannabis use and illicit opioid use among people who use drugs (PWUD) experiencing chronic pain. METHODS AND FINDINGS:This study included data from people in 2 prospective cohorts of PWUD in Vancouver, Canada, who reported major or persistent pain from June 1, 2014, to December 1, 2017 (n = 1,152). We used descriptive statistics to examine reasons for cannabis use and a multivariable generalized linear mixed-effects model to estimate the relationship between daily (once or more per day) cannabis use and daily illicit opioid use. There were 424 (36.8%) women in the study, and the median age at baseline was 49.3 years (IQR 42.3-54.9). In total, 455 (40%) reported daily illicit opioid use, and 410 (36%) reported daily cannabis use during at least one 6-month follow-up period. The most commonly reported therapeutic reasons for cannabis use were pain (36%), sleep (35%), stress (31%), and nausea (30%). After adjusting for demographic characteristics, substance use, and health-related factors, daily cannabis use was associated with significantly lower odds of daily illicit opioid use (adjusted odds ratio 0.50, 95% CI 0.34-0.74, p < 0.001). Limitations of the study included self-reported measures of substance use and chronic pain, and a lack of data for cannabis preparations, dosages, and modes of administration. CONCLUSIONS:We observed an independent negative association between frequent cannabis use and frequent illicit opioid use among PWUD with chronic pain. These findings provide longitudinal observational evidence that cannabis may serve as an adjunct to or substitute for illicit opioid use among PWUD with chronic pain

Evaluation of herbal cannabis characteristics by medical users: a randomized trial

BACKGROUND: Cannabis, in herbal form, is widely used as self-medication by patients with diseases such as HIV/AIDS and multiple sclerosis suffering from symptoms including pain, muscle spasticity, stress and insomnia. Valid clinical studies of herbal cannabis require a product which is acceptable to patients in order to maximize adherence to study protocols. METHODS: We conducted a randomized controlled crossover trial of 4 different herbal cannabis preparations among 8 experienced and authorized cannabis users with chronic pain. Preparations were varied with respect to grind size, THC content and humidity. Subjects received each preparation on a separate day and prepared the drug in their usual way in a dedicated and licensed clinical facility. They were asked to evaluate the products based on appearance (smell, colour, humidity, grind size, ease of preparation and overall appearance) and smoking characteristics (burn rate, hotness, harshness and taste). Five-point Likert scores were assigned to each characteristic. Scores were compared between preparations using ANOVA. RESULTS: Seven subjects completed the study, and the product with highest THC content (12%), highest humidity (14%) and largest grind size (10 mm) was rated highest overall. Significant differences were noted between preparations on overall appearance and colour (p = 0.003). DISCUSSION: While the small size of the study precludes broad conclusions, the study shows that medical cannabis users can appreciate differences in herbal product. A more acceptable cannabis product may increase recruitment and retention in clinical studies of medical cannabis

The Vascular Flora of the Potomac River Watershed of King George County, Virginia

The results of two floristic studies of King George County, Virginia, are combined into an annotated checklist. Field work was initiated in 1983-84 with a study of Caledon Natural Area, a 2,500-acre tract with 3.5 miles of frontage on the Potomac River. Collecting resumed in 1991 and 1992 to include other portions of the county drained by the Potomac River. The study area contains a wide variety of habitats including dry upland woods, mesic ravines, low elevation river flats, beaches, swamps, marshes, and creeks; creeks and marshes include both brackish and freshwater environments. The Potomac River watershed of King George County harbors a diverse assemblage of plants; the checklist includes documentation for 918 species of vascular plants classified in 466 genera and 130 families. This total includes 418 species that at the time of collection were the first records of occurrence in King George County

Verbal conditioning and extinction as a function of operant level, number of verbal responses, and type of reinforcement

LD2668 .T4 1966 W271Master of Scienc

IN-CAM Outcomes Database: Its Relevance and Application in Massage Therapy Research and Practice

One of the most commonly used complementary and alternative medicine (CAM) modalities in North America is massage therapy (MT). Research to date indicates many potential health benefits of MT, suggesting that ongoing research efforts to further elucidate and substantiate preliminary findings within the massage profession should be given high priority. Central to the development of a sound evidence base for MT are the use of valid, reliable, and relevant outcome measures in research, and practice in assessing the effectiveness of MT. The purpose of the present article is to introduce MT researchers and massage therapists interested in using outcome measures in research and clinical practice to the IN-CAM Outcomes Database website by describing the Outcomes Database and identifying its utility in MT research and practice. The IN-CAM Outcomes Database is a centralized location where information on outcome measures is collected and made accessible to users. Outcome measures are organized in the database within the Framework of Outcome Domains. The Framework includes health domains relevant to conventional medicine and CAM alike, and health domains that have been identified as important to CAM interventions. Users of the website may search for information on a specific outcome measure, plan research projects, and engage in discussions related to outcomes assessment in the CAM field with other users and with members of the CAM research community. As the MT profession continues to evolve and move toward evidence-informed practice, the IN-CAM Outcomes Database website can be a valuable resource for MT researchers and massage therapists

Psychometric evaluation of the SF-36 health survey in Medicare managed care

Data quality and scoring assumptions for the SF-36 Health Survey were evaluated among the elderly and disabled, using 1998 Cohort I baseline Medicare HOS data (n=177,714). Missing data rates were low, and scoring assumptions were met. Internal consistency reliability was 0.83 to 0.93 for the eight scales and 0.94 and 0.89, respectively, for the physical (PCS) and mental (MCS) component summary measures. Results declined with increased risk factors (e.g., older age, more chronic conditions), but were well above accepted standards for all subgroups. These findings support using standard algorithms for scoring the SF-36 in the HOS and subgroup analyses of HOS data