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International Telemetering Conference Proceedings / October 17-20, 1994 / Town & Country Hotel and Conference Center, San Diego, California / A significant problem in the processing chain of a low resolution quantization system is the Analog to Digital converter quantization error. The classical model of quantization treats the error generated as a random additive process that is independent of the input and uniformly distributed. This model is valid for complex or random input signals that are large relative to a least significant bit. But the model fails catastrophically for small, simple signals applied to high resolution quantization systems, and in addition, the model fails for simple signals applied to low resolution quantization systems, i.e. one to 6 bits resolution. This paper will discuss a means of correcting this problem by the application of dither. Two methods of dither will be discussed as well as a real-life implementation of the techniques.

The kinetic energy in river streams, tidal currents, or other artificial water channels has been used as a feasible source of renewable power through different conversion systems. Thus, hydrokinetic energy conversion systems are attracting worldwide interest as another form of distributed alternative energy. Because these systems are still in early stages of development, the basic approaches need significant research. The main challenges are not only to have efficient systems, but also to convert energy more economically so that the cost-benefit analysis drives the growth of this alternative energy form. One way to view this analysis is in terms of the energy conversion efficiency per unit cost. This study presents a detailed assessment of a prototype hydrokinetic energy system along with power output costs. This experimental study was performed using commercial low-cost blades of 20 in diameter inside a tank with water flow speed up to 1.3 m/s. The work was divided into two stages: (a) a fixed-pitch blade configuration, using a radial permanent magnet generator (PMG), and (b) the same hydrokinetic turbine, with a variable-pitch blade and an axial-flux PMG. The results indicate that even though the efficiency of a simple blade configuration is not high, the power coefficient is in the range of other, more complicated designs/prototypes. Additionally, the low manufacturing and operation costs of this system offer an option for low-cost distributed power applications.

A murine model was utilized to test the influence of heavy metal protoporphyrins on burn conversion, heme oxygenase – 1 (HO-1) expression, and inflammation. Heavy metal protoporphyrins, such as cobalt protoporphyrin (Co PP) and tin protoporphyrin (Sn PP), were used to influence the heme oxygenase activity. The effects of these heavy metal protoporphyrins on burn wound conversion were examined using a burn comb model in rats. In addition to assessing the extent of conversion, HO-1 expression and parameters of inflammation were also examined in the area of injury (interspace region) subject to conversion. These studies demonstrate proof in principal that pharmacologic agents known to modify HO activity can also modulate burn wound conversion. Improved outcome correlated with HO-1 expression/activity and reduced inflammation. This suggests that one of the mechanisms utilized by HO-1 to improve burn wound outcome involves modulation of one or more components of the inflammatory response.

Thesis advisor: Dunwei Wang / Due to the increasing energy demand from human activities, efficient utilization of renewable energy, such as wind, solar and geothermal energies, becomes necessary and urgent. Photoelectrochemical water splitting offers a great example to convert solar energy and storage it in the term of chemical bond. Seeking suitable photoanode materials becomes the research focus of my study, because the development of photoanode materials significantly lags that of robust photocathode (such as Si). The main challenge is to fabricate an efficient and stable photoanode material which can deliver high photocurrent and sufficient photovoltage which can match well with those of photocathode when made into tandem cell configuration. Hematite (α-Fe2O3) represents a promising metal oxide photoanode material, with a suitable band gap (2.1 eV), low cost and toxicity. Applying nanostructures and appropriate surface modification layers help address existing research challenges. As a result, a much lower turn on potential and greater photocurrent density is achieved. Another photoanode material attracts our attention is tantalum nitride (Ta3N5), with a similar band gap to hematite but much better light absorption properties, shows a poor stability in aqueous electrolyte. For both photoanode materials, thermodynamic and kinetic aspects are studied in details when tested in water splitting devices. These works provide new ideas and insights on the future studies. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Background: Sputum culture conversion at two months is an important indicator for the effectiveness of treatment and the infectivity of a patient with pulmonary TB. This study aimed at investigating factors that are associated with tuberculosis culture conversion at two months as well as investigating whether sputum culture conversion at two months is a reliable predictor of relapse. Methods: The study makes use of data obtained from 347 newly diagnosed tuberculosis patients who participated in a randomized placebo controlled immunotherapy trial at King George V hospital in Durban. Above objectives were met by carrying out statistical analysis of the secondary data. Chi-square tests for categorical explanatory variables such as HIV status and smoking status and (b) t-tests for continuous variables such as age were used for investigating factors associated with 2-month culture conversion. Multivariate models were used to find the most important variables for predicting 2-month culture conversion. Kaplan Meier curves were used for investigating whether culture conversion at two months is a reliable predictor of relapse. Findings: Of the 347 tuberculosis patients, 34 % were HIV sero-positive. Age, body mass index (BMI), smoking status and gender were found to be important variables that affect sputum culture conversion at two months. At 5 % significance level there was no evidence that those who culture convert at two months were less likely to relapse than those who had not culture converted at two months (p=0.1165). However the trend shown is striking to report as it may be of clinical significance. Among those who had not culture converted at two months, more people (40) than expected (34) relapsed an among those who had culture converted at to months, less people (19) than expected (24) relapsed. Interpretation and recommendations: Some behavioral and biological factors affect two month tuberculosis culture conversion therefore successful tuberculosis management need to take into account the effect of these factors. This study did not show that the sterilizing potential of an anti-tuberculosis regimen can be obtained by evaluation of the culture conversion rates at two months and this may be due to small sample size.