Vanessa W Leung

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Decomposition-based quantitative electromyography (DQEMG) comprises a group of methods used to obtain information related to the health of the neuromuscular system. Although primarily objective, aspects of the data analysis protocol include operator decisions that may impact its reliability and reduce the applicability of the technique among multiple users.(More)
OBJECTIVES An artificial saliva (AS) of defined composition is necessary for testing the performance of materials that serve in the mouth as natural saliva is too variable. The chemistry involved is critically important. Many AS recipes can be found in the literature, but the stability of tooth material, i.e. hydroxyapatite (HAP), in most of these has not(More)
OBJECTIVE To survey concentrations and time-variability of the major anions of human saliva using ion chromatography (IC). MATERIALS AND METHODS Resting saliva samples after overnight fasting, obtained under standardized conditions in time-series for 10 subjects, were analysed for chloride, phosphate, nitrate, sulphate, thiocyanate, acetate and lactate. A(More)
OBJECTIVE To use solid titration and laser-scattering end-point detection to determine the hydroxyapatite (HAP) solubility isotherm at 37 degrees C in a plain KCl solution, with CO(2) present, and with additional phosphate. DESIGN Pulverised HAP solid was used to perform a titration to saturation. A very sensitive detector capable of detecting the light(More)
OBJECTIVE Assess the applicability of ion chromatography (IC) for human saliva studies. MATERIALS AND METHODS The behaviour of an ion chromatograph (DX-100, Dionex) in the analysis of human saliva was examined in the following respects: calibration, reproducibility, recovery, and effect of pre-treatment conditions (dilution, temperature). The eluents used(More)
The solution of systems of equilibrium is an important though commonplace operation, rendered difficult by non-linearity. Previous methods of numerical solution have suffered from slow convergence, unreliability, and inefficient structure. An algorithm, RAMESES, is presented in matrix algebra terms, which is both simple in structure and efficient, involving(More)
The algorithm RAMESES has been enhanced by the improvement of the forward extrapolation procedure to give more accurate estimates with a smoothed polynomial function in a dynamically adaptive scheme, ADEPT. A class of problems exhibiting chaotic behaviour due to exaggerated feedback has been controlled by limiting the correction factors. Improved execution(More)
The equations of multiple equilibria systems can be expressed succinctly in matrix algebra terms. This is the basis of the RAMESES algorithm for the solution of those equations. This matrix algebra leads directly to the differential equations for the interdependence of the vector variables of species concentration, component concentration and equilibrium(More)
By the use of a matrix-algebra identity, the algorithm RAMESES for solution of systems of equilibrium equations may be modified to reduce both computer storage requirements and execution time. As a result, standardized formation constants and solubility products are found. This may facilitate compilation of such data in uniform style. An illustrative(More)
The algorithm RAMESES has been made more efficient by incorporation of additional procedures: to extrapolate to the next point by an exact polynomial of any desired order, to control the gain on the adjustment of each independent species, and to optimize the initial guess. The need to consider electroneutrality is emphasized, and some problems with(More)
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