Response times of carbon fiber microelectrodes to dynamic changes in catecholamine concentration

The electrode response time and the measured concentrations during dynamic catecholamine changes were compared using constant potential amperometry and fast-scan cyclic voltammetry. The amperometric response to a rectangular pulse of catecholamine is more rectangular than the cyclic voltammetric response; however, the response times are very similar when, during cyclic voltammetry, the temporal lag due to adsorption and desorption of catecholamine to the electrode is removed by deconvolution. Deconvolution of cyclic voltammetry data was applied to stimulated dopamine release in vivo, allowing for modeling of release and uptake kinetics and to measure catecholamine release from single cells, resulting in better resolution of peaks from single vesicles. In vitro postcalibrations were performed to calculate concentrations of catecholamine measured with cyclic voltammetry and amperometry. The addition of 600 microM ascorbic acid to the postcalibration buffer, allowing a catalytic reaction to regenerate dopamine, resulted in similar calculated concentrations for stimulated release of dopamine using amperometry and cyclic voltammetry. Using deconvoluted cyclic voltammetry to remove the response time lag and adding ascorbic acid to the calibration buffer, the shape and concentration of dynamic catecholamine changes are very similar when measured with constant potential amperometry and cyclic voltammetry.     

Plasticity in anterior hypothalamic vasopressin correlates with aggression during anabolic-androgenic steroid withdrawal in hamsters.

In hamsters, adolescent anabolic-androgenic steroid (AAS) exposure facilitates offensive aggression, in part by altering the development and activity of anterior hypothalamic arginine vasopressin (AH-AVP). This study assessed whether these effects were lasting by examining aggression and AH-AVP during AAS withdrawal. Adolescent hamsters administered AAS were tested as adults for aggression at 1, 4, 11, 18, or 25 days of withdrawal, sacrificed the following day, and examined for AH-AVP afferent innervation using immunohistochemistry. Through Day 12 of withdrawal, aggression and AVP were significantly higher in AAS-treated hamsters than in controls. These differences were no longer observable by Day 19 of withdrawal, at which point the behavior and neurobiology of AAS-treated hamsters reverted to that observed in controls. These data indicate that adolescent AAS exposure has short-term, reversible effects on both aggression and AH-AVP, correlating AH-AVP with the aggressive/nonaggressive behavioral phenotype during AAS withdrawal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Estimation of yellow starthistle abundance through CASI-2 hyperspectral imagery using linear spectral mixture models

The invasive weed yellow starthistle (Centaurea solstitialis) has infested between 4 and 6 million hectares in California. It often forms dense infestations and rapidly depletes soil moisture, preventing the establishment of other species. Precise assessment of its canopy cover, especially low-density abundance in the earlier growing season, is the key to effective management. Compact Airborne Spectrographic Imager 2 (CASI-2) hyperspectral imagery was acquired at the western edge of California's Central Valley grasslands on July 15, 2003. Four linear spectral mixture models (LSMM) were investigated from the original CASI-2 data. Band selections based upon residual analysis and feature extraction (PCA) were further explored to reduce the data dimension. All approaches, except four band-selection unconstrained LSMMs, provide consistent results. The uncertainty of the PCA-based LSMM was estimated through a Monte-Carlo simulation. The maximum standard deviation was approximately 11%. The results suggest that unmixing CASI-2 imagery could be used for estimating and mapping yellow starthistle for larger regional areas.     

Customization of a Commercially Available Prep Scale SFC System to Provide Enhanced Capabilities

Preparative Scale Supercritical Fluid Chromatography is emerging as a powerful alternative to HPLC for the purification and separation of complex chemical reaction mixtures. Advantages include greatly reduced solvent usage (and thus lower cost and environmental impact), higher throughput, and in some cases higher resolution. While there are commercially available prep SFC instruments, none currently offer all the features desired by many medicinal chemists engaged in the drug discovery process. These include: the ability to collect an unlimited number of fractions per sample with high recovery and negligible carryover, fully automated capacity to collect several hundred fractions, and the ability to collect fractions into the same disposable test tubes and racks which are already employed in HPLC. This article describes the customization of a preparatory scale SFC system purchased from Berger Instruments, Inc., Newark, DE. (a subsidiary Mettler-Toledo International, Inc., of Greifensee, Switzerland) in order to provide these capabilities.     

Report of the U.S. Department of Energy Fusion Energy Sciences Advisory Committee (FESAC) Panel Reviewing the Theory and Computing Program

This Panel was set up by the Fusion Energy Sciences Advisory Committee (FESAC) at its November 2000 meeting for the purpose of addressing questions from the Department of Energy concerning the theory and computing/simulation program of the Office of Fusion Energy Sciences. Although the Panel primarily addressed programmatic questions, it acknowledges that the theory and computing in fusion energy sciences has a stellar record of research successes. (A recent FESAC report entitled Opportunities in the Fusion Energy Sciences Program listed a number of theory and computing research highlights.) Last year the National Research Council performed an assessment of the quality of the fusion energy sciences program—including theory and computing—and concluded that the quality of its research is on a par with that of other leading areas of contemporary physical science.     

Problem solving: A model for supervision in professional psychology.

Reviews literature on problem-solving models, their application to psychology and other fields, models of supervision, and supervision in psychology. The following processes are addressed: problem identification, generation of alternative solutions, solution evaluation, decision making, performance, and outcome evaluation. Implementation of the problem-solving model and possible sources of difficulty are discussed. This model has the advantages of being atheoretical, systematic, and appropriate for use in clinical, counseling, and school psychology. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The impact of a conceptual solar thermal electric conversion plant on regional meteorological conditions: A numerical study

A two-dimensional, mesoscale model of the atmosphere that incorporates hydrodynamic, thermodynamic, and microphysical processes has been applied to simulate the impact on regional weather of a solar thermal electric conversion (STEC) installation in southern Spain. The STEC plant is conceptualized to occupy an area of 1,000 km² with heliostats covering 25 per cent of the total power plant area. It is assumed to use wet natural draft cooling towers for dissipating waste heat into the atmosphere.The 2-D model is applied to a STEC facility that covers a distance of 32 km in the horizontal with heliostats installed in the middle over a distance of 8 km. The model has been integrated for 9 hr of real time for both typical summer and winter conditions.The results of integration for summer indicate that a STEC installation of the above size has considerable potential for modifying regional weather. Clouds formed after 5 hr of real-time integration and persisted until the end of the integration; rainfall also occurred. In contrast, clouds did not form until 7 hr of real-time integration without the installation and were more sporadic and transient; rainfall was much less.The results for winter conditions do not show any cloud formation after 9 hr of real-time integration. This difference between summer and winter cases is attributed to the very strong winds used as initial conditions for the winter simulation.     

Mars laser hygrometer

We have designed and built a miniature near-IR tunable diode laser (TDL) spectrometer for measuring in situ the water vapor mixing ratio either in the Martian atmosphere or thermally evolved from Martian soil or ice samples. The laser hygrometer uses a thermoelectrically cooled single-mode distributed-feedback TDL at 1.87 microm to scan over a selected vibration-rotation line of both H2O and CO2 near 5327.3 cm(-1). A working prototype that weighs only 230 g has been built and used to generate spectra whose analysis demonstrates precision sensitivities as fine as 1 part in 10(6) by volume in 1 s or 0.1 part in 10(6) in 10 s at Martian pressures and temperatures. Absolute uncertainties of approximately 5% are calculated.