Simulation of programmable logic controller

The development and test of a PLC control program takes time, increases equipment down-time, and might damage hardware due to program errors. All of these problems can be eliminated if there is a computer simulation system for testing control programs off line. This paper presented a new method, called Direct Sequential Method, for simulating PLCs. This method resolves a ladder logic sequentially by applying a series of logic deductions. This simulation system has been implemented in C and tested successfully.     

Molecular studies on kinin receptors

We describe the results of functional studies on DNA clones encoding functional bradykinin receptors derived from human, rat, and mouse sources and including both genomic and complementary DNA clones. In both the Xenopus oocyte and the COS cell expression systems, the receptors from human and rat showed the pharmacological properties of B2 receptors, but receptors from mouse displayed both B1- and B2-like pharmacological properties. We further investigated the molecular relationship between the B1 and B2 receptor subtypes expressed by a human fibroblast cell line, and we demonstrate that these two receptor subtypes are encoded by distinct mRNA species.     

Contractile responses and structure of small bronchi isolated from rats after 20 months' exposure to ozone

Short-term exposure to high concentrations of ozone has been shown to increase airway responsiveness in normal humans and in all laboratory animal species studied to date. While our knowledge concerning the pulmonary effects of single exposures to ozone has increased rapidly over recent years, the effects of repeated exposures are less understood. The goal of the present study was to determine whether airway responsiveness is increased after near-lifetime exposure to ozone. Airway segments representing approximately eighth generation airways were isolated from Fischer 344 rats of both genders that had been exposed for 6 hr per day, 5 days per week for 20 months to 0, 0.12, 0.5, or 1.0 parts per million (ppm) ozone. Circumferential tension development was measured in isolated airways in response to bethanechol, acetylcholine, and electrical field stimulation. Responsiveness of the airways to the contractile stimuli was described by the effective dose or frequency that elicited half-maximum contraction (ED50) and the maximum response. Since ozone exposure is associated with remodeling of peripheral airways, smooth muscle area was determined and tension responses were normalized to the area measurements. Before normalization of tension data to smooth muscle area, neither the ED50 nor maximum response of small bronchi to the contractile stimuli was altered after chronic ozone exposure. Smooth muscle area was greater in airways isolated from animals that had been exposed to 0.5 ppm ozone. After accounting for smooth muscle area, maximum responses of the small bronchi isolated from male rats were significantly reduced after 0.12 and 0.5 ppm ozone. Although not significant statistically, a similar trend was observed in airways isolated from female rats. These results suggest that the increase in airway responsiveness associated with acute ozone exposure does not persist during near-lifetime exposure. Although the mechanism responsible for the adaptation to the effects of O3 on airway responsiveness is unknown, the results indicate that smooth muscle cell function was compromised by the chronic exposure. The mechanism(s) responsible for mediating this effect and the relevance of these results to humans remains to be determined.     

Singular Tetrahedral Finite Elements for Vector Electromagnetics

The electromagnetic fields at reentrant edges made of conductor are generally singular and the polynomial basis functions used in traditional finite elements do not model the fields well in these regions. Two new tetrahedral elements are introduced with basis functions that incorporate the known asymptotic variation of the fields with distance from the edge. The basis is split into gradient and rotational parts. Additional vertex functions can be added to improve the conditioning of the global matrix system that arises in the time-harmonic case. Results are presented for the scattering parameters of a number of waveguide discontinuities. The new elements reduce the error considerably compared to the Whitney element, and generally outperform the second-order edge element, even though that has more degrees of freedom     

Treatment algorithm use to optimize management of symptomatic patients with a history of mania

BACKGROUND: While monotherapy has significant limitations in bipolar disorder, few published data addressing alternatives exist. Treatment algorithms have been proposed, but none have undergone empirical evaluation. This study provides a systematic prospective, open evaluation of the effectiveness and tolerability of a treatment algorithm for patients with histories of mania. METHOD: Twenty-eight symptomatic outpatients from a public mental health facility who were diagnosed as having either bipolar I or schizoaffective illness, bipolar type, entered the study. Minimum blood levels of lithium and divalproex sodium were defined. Medications were pushed to predetermined levels (as tolerated) before proceeding to the next algorithm step. Clinical symptoms were assessed monthly using the Brief Psychiatric Rating Scale (BPRS, 27 item) and Clinical Global Impressions scale. RESULTS: Pretreatment and posttreatment clinical symptoms were compared. Over 50% of patients attained 30% improvement from baseline BPRS after 4 months. Thirty-six percent of patients (N = 10) became mood stable, 46% (N = 13) remained mood unstable, and 18% (N = 5) dropped out before completing the algorithm. Although patients who finished the algorithm were taking more medication, either dosage and/or drugs, somatic complaints did not increase. CONCLUSION: The potential benefit of a defined treatment algorithm was demonstrated for these complex and persistently ill patients. Despite long treatment histories, patients improved with more frequent visits and addition of medication(s). A randomized controlled trial comparing a similar treatment algorithm with treatment-as-usual is warranted.