Atmospheric pressure, glow discharge, optical emission source for the direct sampling of liquid media

A glow discharge spectroscopy (GDS) source operates at atmospheric pressure. One of the discharge electrodes of the device is formed by an electrolytic solution 27 containing the analyte specimen. The passage of electrical current (either electrons or positive ions) across the solution/gas phase interface causes local heating and the volatilization of the analyte species. Collisions in the discharge region immediately above the surface of the solution results in optical emission and ionization that are characteristic of the analyte elements. As such, these analyte elements can be identified and quantified by optical emission spectroscopy (OES) or mass spectrometry (MS). The device uses the analyte solution as either the cathode or anode. Operating parameters depend on the electrolyte concentration (i.e. solution conductivity) and the gap 35 between the solution surface and the counter electrode. Typical conditions include discharge currents of about 10 to about 60 mA and potentials of about 200 to about 1000 volts. Electrolyte solutions of pH, pNa or pLi values of about 0.5 to about 2 and interelectrode gaps of about 0.5 to about 3 mm produce stable plasmas where the analyte solutions are totally consumed at flow rates of up to about 2.0 mL/min

Cholinergic suppression: A postsynaptic mechanism of long-term associative learning

Food avoidance learning in the mollusc Pleurobranchaea entails reduction in the responsiveness of key brain interneurons in the feeding neural circuitry, the paracerebral feeding command interneurons (PCNs), to the neurotransmitter acetylcholine (AcCho). Food stimuli applied to the oral veil of an untrained animal depolarize the PCNs and induce the feeding motor program (FMP). Atropine (a muscarinic cholinergic antagonist) reversibly blocks the food-induced depolarization of the PCNs, implicating AcCho as the neurotransmitter mediating food detection. AcCho applied directly to PCN somata depolarizes them, indicating that the PCN soma membrane contains AcCho receptors and induces the FMP in the isolated central nervous system preparation. The AcCho response of the PCNs is mediated by muscariniclike receptors, since comparable depolarization is induced by muscarinic agonists (acetyl-ß -methylcholine, oxotremorine, pilocarpine), but not nicotine, and blocked by muscarinic antagonists (atropine, trifluoperazine). The nicotinic antagonist hexamethonium, however, blocked the AcCho response in four of six cases. When specimens are trained to suppress feeding behavior using a conventional food-avoidance learning paradigm (conditionally paired food and shock), AcCho applied to PCNs in the same concentration as in untrained animals causes little or no depolarization and does not initiate the FMP. Increasing the concentration of AcCho 10-100 times, however, induces weak PCN depolarization in trained specimens, indicating that learning diminishes but does not fully abolish AcCho responsiveness of the PCNs. This study proposes a cellular mechanism of long-term associative learning -- namely, postsynaptic modulation of neurotransmitter responsiveness in central neurons that could apply also to mammalian species

An Analysis of the Factors Affecting the Career Orientation of Federal Civilian Engineers

This study was conducted to analyze the factors that affect the career orientation of federal civilian engineers at the Naval Avionics Center in Indianapolis, Indiana. One hundred and sixty-seven scientists and engineers from several engineering divisions were surveyed regarding turnover intentions. Based on literature reviews in the area of turnover with this particular population, a model was developed containing several factors related to intent to remain in the organization. Results indicated that this model predicts the turnover intention with 87.5 percent accuracy. Findings are interpreted in light of ongoing efforts on an organization-wide basis to introduce change in the Center's culture through a quality management program. Keywords: Career orientation, Job satisfaction turnover. (sdw)Naval Avionics Center, Civilian Personnel Departmenthttp://archive.org/details/analysisoffactor00robeN0016389WR90118NAApproved for public release; distribution is unlimited

Process Control of Activated Sludge Treatment

General feed forward controllers, conforming to standard control modes, have been derived for an activated sludge process. The analysis indicated that the appropriate controllers are proportional control with measurement of substrate flow rate, and derivative control with measurement of inlet substrate concentration, and manipulation of the rate of return sludge by both controllers. The performance of these controllers was tested by computer simulation of five dynamic aerator models with and without sludge storage, and with two settling basin models. In all cases significant reduction of the maximum exit substrate concentration was achieved. Additional improvement resulted from the use of sludge storage. As the aerator model became more linear the control results also improved. The first dynamic results were obtained using a perfect steady state settler model, the remainder assumed that the settler dynamics could be represented by a variable time delay. The addition of the settler dynamics caused the control to degrade somewhat. Finally the generality of the two controllers was proved mathematically for the five biological kinetic models for substrate utilization and bacterial growth

Radio astronomy

The following subject areas are covered: (1) scientific opportunities (millimeter and sub-millimeter wavelength astronomy; meter to hectometer astronomy; the Sun, stars, pulsars, interstellar masers, and extrasolar planets; the planets, asteroids, and comets; radio galaxies, quasars, and cosmology; and challenges for radio astronomy in the 1990's); (2) recommendations for new facilities (the millimeter arrays, medium scale instruments, and small-scale projects); (3) continuing activities and maintenance, upgrading of telescopes and instrumentation; (4) long range programs and technology development; and (5) social, political, and organizational considerations

2018 – 2019 Kentucky Agricultural Economic Situation and Outlook

This publication covers the situation and outlook for 2018-2019 in the following areas: U.S. Agricultural Economy; Kentucky’s Agricultural Economy; Selected Commodity Profiles - Cattle; Poultry; Hogs; Equine; Dairy; Corn; Soybeans; Wheat; Tobacco; Fruits, Vegetables and Greenhouse; and Forestry