Direct comparison of three methods for the determination of radon in well water

Radon concentrations obtained using a bubbler device developed to collect and bubble water samples in the laboratory and field were compared with results from conventional liquid scintillation counting. Measurements from standard solutions with a wide concentration range showed excellent agreement between liquid scintillation and results obtained using the bubbler device in conjunction with alpha-scintillation cells. Measurements of waterborne radon concentrations in 110 community and private wells in New York State ranged from 1 to 4,100 Bq L-1, with arithmetic and geometric means of 200 and 30 Bq L-1, respectively. Excellent agreement between the analytical techniques was obtained for each field site.     

Modeling obesity using abductive networks

This paper investigates the use of abductive-network machine learning for modeling and predicting outcome parameters in terms of input parameters in medical survey data. Here we consider modeling obesity as represented by the waist-to-hip ratio (WHR) risk factor to investigate the influence of various parameters. The same approach would be useful in predicting values of clinical parameters that are difficult or expensive to measure from others that are more readily available. The AIM abductive network machine learning tool was used to model the WHR from 13 other health parameters. Survey data were collected for a randomly selected sample of 1100 persons aged 20 yr and over attending nine primary health care centers at Al-Khobar, Saudi Arabia. Models were synthesized by training on a randomly selected set of 800 cases, using both continuous and categorical representations of the parameters, and evaluated by predicting the WHR value for the remaining 300 cases. Models for WHR as a continuous variable predict the actual values within an error of 7.5% at the 90% confidence limits. Categorical models predict the correct logical value of WHR with an error in only 2 of the 300 evaluation cases. Analytical relationships derived from simple categorical models explain global observations on the total survey population to an accuracy as high as 99%. Simple continuous models represented as analytical functions highlight global relationships and trends. Results confirm the strong correlation between WHR and diastolic blood pressure, cholesterol level, and family history of obesity. Compared to other statistical and neural network approaches, AIM abductive networks provide faster and more automated model synthesis. A review is given of other areas where the proposed modeling approach can be useful in clinical practice.     

A quantitative framework for analyzing epicardial activation patterns during ventricular fibrillation

We have developed a method for quantifying the complexity of activation patterns observed during ventricular fibrillation (VF) that is based on our previously reported methodology for decomposing epicardial mapping data into a set of isolated wavefronts. One-half second datasets are acquired from a 21 x 24 array of unipolar electrodes (1 mm spacing), and the wavefronts are isolated. A correlation technique is used to compute the similarity between all possible pairs of the isolated wavefronts. From these data, the wavefronts are sorted into clusters, each of which represents a recurring wavefront morphology. We define multiplicity (M) as the number of clusters needed to account for 90% of the total activations in the VF episode. M measures the complexity of the rhythm. In repetitive patterns (e.g., sinus rhythm), M = 1, indicating that the same morphology repeatedly activates the mapped region. Typically, in VF, M > 1, with larger numbers representing more complex, disorganized patterns. As an example, we computed M at 5, 10, 15, and 20 sec after electrical induction of VF in six pigs. M decreased significantly (p < 0.001), suggesting increasing organization during this period.     

Nonopioid analgesics shorten the duration of postoperative ileus

Morphine inhibits propagating and stimulates nonpropagating colon contractions in monkeys and humans. The use of morphine or other opioids that inhibit propulsive contractions prolongs postoperative ileus. In contrast, ketorolac tromethamine, a nonsteroidal analgesic, has no effect on colon contractions in monkeys. In 14 patients having elective abdominal operations, bipolar electrodes were implanted on the right (n = 13) and left (n = 10) colon. Group A (n = 8) received ketorolac, 30 mg IM q6h, for pain relief. Group B (n = 6) needed supplemental morphine, 2-10 mg IV or IM, plus ketorolac to control their pain. Myoelectric activity was recorded from each subject on postop Days 1-5 and analyzed by computer for electrical control activity (ECA), short and long electrical response activity (ERA), and propagation of long ERA. There was a difference between the two groups in return of propagated long ERA bursts that correlated with clinical recovery from postoperative ileus. Postoperative analgesia with ketorolac resulted in faster resolution of ileus compared to morphine plus ketorolac because opioid-induced motor abnormalities in the colon were avoided.