Method for Measuring Dipole Parameters of Isolated Hearts and Muscles?Application to Frog Gastrocnemius

Resistor networks were developed to measure the magnitude, direction, and location of the resultant dipole moment of isolated hearts or muscles located at the center of a fluid-filled dish. With the network connected to the dish electrodes, these quantities could be determined from only four bipolar voltage measurements. Energized muscle strips were simulated by dipping pieces of metal of different lengths into the electrolyte. The resultant location was found to be midway between the centers of the two pieces, rather than at the gap between them.     

Isolation of a spotted fever group rickettsia from the Pacific Coast tick, Ixodes pacificus, in Oregon

A rickettsia of the spotted fever group was isolated on three occasions from Ixodes pacificus in western Oregon. These isolations, and additional evidence furnished by complement fixation tests on guinea pigs inoculated with other Oregon ticks of this species, indicate that the association of this rickettsia with the Pacific Coast tick may be widespread. This is the first isolation of a spotted fever group rickettsia from I. pacificus. Because the Oregon isolates are mildly virulent for guinea pigs they resemble the Western U and Rickettsia montana strains of rickettsiae. However, preliminary evidence from cross-immunofluorescence tests of mouse antisera suggests the Tillamook and Grants Pass strains are antigenically different from all known spotted fever group agents.     

A Capital Budgeting Heuristic Algorithm Using Exchange Operations

A heuristic algorithm for solving capital budgeting problems is described. The algorithm proceeds from an initial solution, obtained with the use of ranking procedures, and progressively improves the solution through exchange operations. Computational experience in solving a set of 30-variable, 5-constraint problems is described and the approach to optimal values with increasing computation time is shown. The results show considerable time advantage over 0-1 implicit enumeration techniques. In only two of twenty-eight problems were the solutions nonoptimal, and in these two cases the objective function values for the heuristic solutions were within 0.5 percent of those for the optimal solutions. A brief investigation was conducted on larger problems (60 variables, 5 constraints); the time advantage is even greater on problems of that size. Details of the problems and their optimal solutions are available to interested readers upon request to the author.     

The effect of respiratory immunization on cell-mediated immune effector cells of the lung

In order to understand the mechanisms of cellular immune injury in hypersensitivity pneumonitis, the effect of type of antigen on cell-mediated immunity in guinea-pigs receiving respiratory immunization was studied. Lymphocytes obtained by pulmonary lavage were compared with those from peritoneal exudate following immunization with either a soluble protein, human serum albumin, or a particulate suspension of Thermoactinomyces vulgaris. Assays were obtained without mixing cells from these two sources. Statistically significant increases (13-22%) in the number of alveolar rosette-forming cells (RFC) were found in the animals immunized with either antigen, but only the particulate T. vulgaris was also capable of inducing a systemic increase of such cells. That this increase in RFC could be due to specifically reactive lymphocytes was demonstrated by the production of antigen-stimulated macrophage migration inhibition. Some evidence was obtained that indicated that T. vulgaris could act both as a non-specific B-cell stimulant and a specific T-cell activator. The concept of a hypothetical pulmonary 'barrier' is discussed which must be overcome to induce systemic immune responses following respiratory immunization. T. vulgaris must be added to the list of known agents or means for overcoming this 'barrier'.     

Phosphorus removal in the activated sludge process

The results from this research suggest that both calcium phosphate precipitation and enhanced biological uptake play a role in phosphorus removal in the activated sludge process when a non-nitrifying, anaerobic-aerobic system is used to treat a low calcium wastewater. The primary removal mechanism was found to be biological uptake, as calcium phosphate precipitation accounted for only 15–27% of the total phosphorus removed. Calcium phosphate precipitation in the aerobic unit was enhanced because of the pH increase in that reactor. This was the result of low CO₂ production (indicated by low specific oxygen uptake values) and intense aeration which caused excessive CO₂ stripping in the aerobic unit     

Outcome of unsuspected pneumococcemia in children not initially admitted to the hospital

The records were reviewed of 97 episodes of unsuspected pneumococcemia in children not initially admitted to the hospital. Antimicrobial agents were prescribed at the first visit for 46 children; at the second visit 37 of them were improved and nine were not. No antimicrobial agents were prescribed at the first visit for 51; at the second visit 16 of these patients were improved and 35 were not. Pneumococcemia persisted in two treated children and in 13 untreated children. Meningitis was identified later in four children (two treated and two untreated). Although pneumococcemia in children may be a transient event, it may also persist or result in meningitis or other localized infections.     

A dynamical model for generating synthetic electrocardiogram signals

A dynamical model based on three coupled ordinary differential equations is introduced which is capable of generating realistic synthetic electrocardiogram (ECG) signals. The operator can specify the mean and standard deviation of the heart rate, the morphology of the PQRST cycle, and the power spectrum of the RR tachogram. In particular, both respiratory sinus arrhythmia at the high frequencies (HFs) and Mayer waves at the low frequencies (LFs) together with the LF/HF ratio are incorporated in the model. Much of the beat-to-beat variation in morphology and timing of the human ECG, including QT dispersion and R-peak amplitude modulation are shown to result. This model may be employed to assess biomedical signal processing techniques which are used to compute clinical statistics from the ECG.     

Analysis of octyl- and nonylphenol and their ethoxylates in water and sediments by liquid chromatography/tandem mass spectrometry

The ubiquitous presence of alkylphenol ethoxylates in the environment as well as concern for endocrine disruption effects in biota caused by their degradation products (such as octyl- and nonylphenol) has raised interest in the environmental fate of these compounds. As part of an effort to model their behavior in a subestuary of the Chesapeake Bay, a quantitative method for the analysis of octyl- and nonylphenol, and their ethoxylates (1-5) in water and sediment was developed. Extraction procedures are based on solid-phase extraction techniques. Identification and quantitation of the analytes is done by liquid chromatography coupled to tandem mass spectrometry. Instrument detection limits for the compounds ranged from 0.1 to 9 pg injected on column, which allowed method detection limits of 0.04-3 ng/L in water and 0.2-13 ng/g of dry weight in sediment. The method was used to analyze water and sediment from the Back River, MD, where concentrations for the individual compounds ranged from <8 to 200 ng/L in water and <9 to 6700 ng/g of dry weight in sediment. Additionally, structural information obtained in the mass spectrometer is presented that supports previous observations that nonylphenol and its ethoxylates are composed mainly of isomers with a tertiary alpha-carbon.