Enhanced real-time cyanobacterial fluorescence monitoring through chlorophyll-a interference compensation corrections.

In situ fluorometers can be used as a real-time cyanobacteria detection tool to maintain safe drinking and recreational water standards. However, previous studies into fluorometers have established issues arising mainly from measurement inaccuracies due to green algae interference. Therefore, this study focusses on developing correction factors from a systematic study on the impact of green algae as an interference source. This study brings a novel technique where the chlorophyll-a (Chl-a) and phycocyanin measurements are used to correct the fluorometer output for interference bias; four fluorometers were tested against three key cyanobacterial species and the relationship between phycocyanin output, green algae and cyanobacteria concentrations were investigated. Good correlation (R2 > 0.9, p-value < 0.05) was found between the fluorometer phycocyanin output and increasing green algae concentration. The optimal correction method was selected for each of the fluorometer and cyanobacteria species pairs by validating against data from the investigation of green algae as an interference source. The correction factors determined in this study reduced the measurement error for almost all the fluorometers and species tested by 21%-99% depending on the species and fluorometer, compared to previous published correction factors in which the measurement error was reduced by approximately 11%-81%. Field validation of the correction factors showed reduction in fluorometer measurement error at sites in which cyanobacterial blooms were dominated by a single species.

A formulation of the infinite strip resonator problem.

The geometrical theory of diffraction has been used to formulate the infinite strip resonator problem. The conditions of large mirror size and large separation of the end mirrors in the Fox and Li formulation can be removed under this alternative scheme. Diffraction losses and phase shifts are given for resonators of Fresnel number from 0.56 to 0.01.

Grating coupled compound resonators.

A simple model, based on a simple boundary condition at the grating coupling surface, is constructed for a grating coupled cavity. The physical meaning of the boundary condition is discussed, and the gain factor and phase shift of the coupled resonator are studied in terms of the properties of the grating and the reflectivities of the mirrors.

Prediction of the mediastinal drainage after coronary artery bypass surgery.

Using multiple correlation and linear regression approaches, we investigated the association between the amount of mediastinal drainage for the first 24 postoperative hours and clinical variables as well as multiple haematological tests performed at three time points: before anaesthesia induction, 10 minutes after protamine administration and just after skin closure, on 46 patients undergoing primary coronary artery bypass grafting. Three models from the three times were then developed to predict mediastinal drainage. The number of internal mammary grafts, the total number of grafts and plasma fibrinogen concentration were useful predictors of mediastinal drainage at all three times. The platelet count taken only after skin closure was found to provide additional predictive information. Each regression model explained approximately 60% of the variation in postoperative mediastinal drainage. The information obtained from these predictive models is useful in defining high-risk populations.