ABSTRACT
Changes in the sequence or pattern of R-R intervals is an integral part of electrocardiogram detection of most clinically important arrhythmias. Moreover, there is inherent interest in these patterns and their method of study as basic physiological phenomena. Prediction of R-R interval changes based on past history and detection of departure from an established pattern have been utilized in automated monitoring strategies and algorithms. The studies described her further clarify the usefulness of Markov processes for this purpose, compare the accuracy of linear and nonlinear regression models, and indicate some advantages of both.
Subject(s)
Arrhythmias, Cardiac/diagnosis , Diagnosis, Computer-Assisted , Electrocardiography/methods , Arrhythmias, Cardiac/physiopathology , Heart Conduction System/physiopathology , Humans , Regression AnalysisABSTRACT
An automated technique for EEG frequency analysis was employed in the study of nine children with sickle cell disease. Quotients, Q(1) (delta+theta/alpha+beta) and Q(2) (theta/alpha+8), were calculated from the computed power in each frequency range. Recordings from occipital-parietal and temporal-frontal areas resulted in a higher Q(1) for sickle cell disease patients than for reported normals (p<.002 and p<.05 respectively). Q(2) value from the occipital-parietal sites were also higher for the sickle cell group (p<.05).The technique reported here lends itself to serial studies in appropriate patient groups and suggests the possibility of an organic basis for some of the results found.
Subject(s)
Anemia, Sickle Cell/physiopathology , Brain/physiopathology , Electroencephalography , Adolescent , Child , Child, Preschool , Humans , Pilot ProjectsABSTRACT
Direct optical scanning of solute boundaries in large zone gel chromatography experiments provides an accurate means of determining boundary profile shapes and rates of motion. A method has been developed for correcting such boundaries to a constant time frame, eliminating the distortion which arises from finite column scanning rate. Centroids of the corrected profiles can be used to determine the partition cross section for the solute of interest. The partition cross section and flow rate determine translational motion within the column. The axial dispersion coefficient, L, which characterizes rate of boundary spreading may also be calculated from the profiles. In order to explore these procedures a study of four noninteracting solutes was conducted. Partition cross sections determined from rates of motion of boundary centroids were found to be in good agreement with those determined by the equilibrium saturation method on the same column. In order to explore the lowest concentration limits of the technique and to illustrate the boundary characteristics for a self-associating solute, a study of carboxyhemoglobin was conducted over a wide concentration range. From measurements at 220 nm the lowest concentration where useful data could be obtained was 2 micrograms per ml (0.12muM heme). These results establish validity of the procedures used in analyzing the rates of boundary transport and in studying solute transport over a wide range of conditions.
