Integral equation formulation for buoyancy-driven convection problems

An integral equation formulation for buoyancy-driven convection problems is developed and illustrated. Buoyancy-driven convection in a bounded cylindrical geometry with a free surface is studied for a range of aspect ratios and Nusselt numbers. The critical Rayleigh number, the nature of the cellular motion, and the heat transfer enhancement are computed using linear theory. Green's functions are used to convert the linear problem into linear Fredholm integral equations. Theorems are proved which establish the properties of the eigenvalues and eigenfunctions of the linear integral operator which appears in these equations.     

Decision analysis in clinical practice

Medical diagnosis and treatment, as examples of decision making under uncertainty, provide an ideal setting for the application of decision analysis. The paper, in selecting reports of medical decision analysis. discusses the usefulness of elements in decision analysis to the clinical setting. These include decision trees, probability assessments, and utility theory. Some concepts are welcomed by the medical profession and should be utilized to their utmost. However, some reported applications cannot be practically implemented for such reasons as physician time constraints and professional opposition. The paper identifies classes of clinical decision problems which are amenable to decision analysis and proposes ways of adapting the theory to clinical practice.     

Permanently oriented antibody immobilization for digoxin determination with a flow-through fluoroimmunosensor

This paper reports a new flow-through fluoroimmunosensor, the function of which is based on antibodies immobilized on an inmunoreactor of controlled-pore glass (CPG), for determination of digoxin, used in the treatment of congestive heart failure and artery disease. The immunosensor has a detection limit of 1.20 microg L(-1) and provides high reproducibility (RSD=4.5% for a concentration of 0.0025 mg L(-1), and RSD=6.7% for 0.01 mg L(-1)). The optimum working concentration range was found to be 1.2 x 10(-3)-4.0 x 10(-2) mg L(-1). The lifetime of the immunosensor was about 50 immunoassays; if stored unused its lifetime can be extended to three months. A sample speed of about 10-12 samples per hour can be attained. Possible interference from substances with structures similar to digoxin (morphine, heroin, tebaine, codeine, pentazocine and narcotine) was investigated. No cross-reactivity was seen at the highest digoxin: interferent ratio studied (1:100). The proposed fluoroimmunosensor was successfully used to determine digoxin concentrations in human serum samples.     

A signal processing algorithm for reflection from extended targets

A spectral-analysis procedure is proposed for processing signals reflected from extended targets. Some issues of algorithm design and implementation are considered for this class of problems, such as frequency band computation, spectral estimation, etc. Results of numerical processing of empirical data are presented.Translated from Vychislitel'naya Matematika i Matematicheskoe Obespechenie EVM, pp. 102–108, 1985.     

Use of dynamics spectral transform in identification problems

Translated from Matematicheskie Modeli i Optimizatsiya Vychislitel'nykh Algoritmov, pp. 106–111, 1994.