A Far Infrared Metal Waveguide Laser System Optically Pumped Using A Modular Carbon Dioxide Dielectric Waveguide Laser

The theory, design, and construction of an optically pumped far infrared laser is described. The pump source consists of a carbon-dioxide waveguide laser which injects several watts of 10 (mu)m wavelength radiation into a metallic waveguide FIR resonator containing a molecule active in the far infrared. The frequency of the pump laser is monitored using a heterodyne technique and can be stabilized on the peak of the optoacoustic absorption signal of the FIR active medium. System operation is verified for known FIR stimulated emissions of optically pumped methyl alcohol. The wide tuning range of the CO(,2) waveguide pump laser allows excitation of CH(,3)OH pump absorption lines located within (+OR-)115 MHz from the CO(,2) emission line center.;The waveguide pump laser is constructed from four identical beryllium oxide waveguide sections connected in series. The modular concept permits the assembly of waveguide lasers with resonator lengths appropriate for specific laser applications. A high voltage trigger pulser is used to initiate the separate discharges. Successful implementation of an optovoltaic probe for frequency stabilization is demonstrated. Waveguide Brewster\u27s window extensions, a variable output coupling waveguide etalon, and a two element external cavity reflector were developed to enhance laser performance.;The pump radiation is conducted into the FIR cavity using an alumina waveguide through a hole in the end mirror with very low power loss and minimal beam divergence. Output FIR radiation was detected using a pyroelectric detector contained within the cavity chamber. The compact detector unit includes an integral optical chopper and quartz lens.;Output power vs gain length data from the modular CO(,2) waveguide laser permitted the calculation of small signal gain and saturation intensity for various laser gas mixtures. The results so obtained extend the known values of these parameters to higher operating pressures and larger helium fractions. Saturation intensity was found to be dependent upon the fraction of CO(,2) in the gas mixture. The discharge current for optimal power output increased with laser gain.;The optically pumped FIR laser system can be used to investigate lasing for unstudied molecules and pump off-set frequencies or as a source of stable coherent FIR radiation suitable for spectroscopic applications

Development of a Quantum Chemical Two-Electron Integral Program for a Hierarchical Distributed Shared Memory Multiprocessor System (MEMSY)

A quantum mechanical integral program has been implemented on a multiprocessor system with a hierarchical architecture, having at the same time a global memory and a locally distributed memory. Due to this hardware concept the possibilities of communication are manifold and therefore more complexin comparison with other multiprocessor systems, e.g. Intel iPSC/860 or workstation clusters. Nevertheless, the efficiencyobtained using asimulator or the real system are of comparable quality. It is expected that this variety of interprocessor communications can be employed to its full extent in the second part of the program in which hermitian eigenvalue problems have to be solved many times

Evaluating the Effectiveness of Regulatory Stormwater Monitoring Protocols on Groundwater Quality in Urbanized Karst Regions

Non-point pollution from stormwater runoff is one of the greatest threats to water quality in the United States today, particularly in urban karst settings. In these settings, the use of karst features and injection wells for stormwater management results in virtually untreated water being directed into the karst aquifer. Currently, no policies exist specifically to provide water quality protections to karst environments. This study utilized a combination of karst stormwater quality data, along with survey data collected from MS4 Phase II communities, and an analysis of current federal, local, and state water quality regulations, to assess the need for karst-specific water quality regulations. Water quality data indicate that significant levels of contamination are mobilized during storm events, and often are directed into the karst system via Class V injection wells. Survey data collected from MS4 stakeholders in the karst regions of Kentucky indicate stakeholders are generally unable to explain local karst regulations or the steps taken to develop them. This confusion comes in part from insufficient progress on evaluation criteria available for the MS4 Minimum Control Measures (MCMs). Karst waters are often placed into the legal “gray zone” due in part to differences in definitions of key terms in state and federal regulations. This study recommends the development of regulations specific to karst waters at the state and federal levels through either the adaptation of existing or creation of new policies, which place an emphasis on the integration of water quality monitoring and karst education

Spatial decisions and cognitive strategies of monkeys and humans based on abstract spatial stimuli in rotation test

We showed previously that macaque monkeys (Macaca mulatta) could orient in real space using abstract visual stimuli presented on a computer screen. They made correct choices according to both spatial stimuli (designed as an abstract representation of a real space) and nonspatial stimuli (pictures lacking any inner configuration information). However, we suggested that there were differences in processing spatial and nonspatial stimuli. In the present experiment we show that monkeys could also use as a cue abstract spatial stimuli rotated with respect to the real response space. We studied the ability of monkeys to decode abstract spatial information provided in one spatial frame (computer screen) and to perform spatial choices in another spatial frame (touch panel separated from the screen). We analyzed how the monkeys were affected by the type of training, whether they perceived the stimuli as “spatial” or “nonspatial,” and which cues they used to decode them. We compared humans to monkeys in a similar test to find out which cognitive strategy they used and whether they perceive spatial stimuli in the same way. We demonstrated that there were two possible strategies to solve the task, simple “fitting” ignoring rotations and “remapping,” when the stimulus was represented as an “abstract space” per se