Ethanol increases GABAA responses in cells stably transfected with receptor subunits

Ethanol enhancement of GABAA receptor function has been found in some, but not all, studies. These results suggest the existence of ethanol-sensitive and -resistant receptors that may differ in subunit composition, although methodological differences (e.g., 36Cl- flux versus membrane currents) could also contribute to the different results. To examine these possibilities, we used mouse L(tk-) cells stably transfected with alpha 1 + beta 1 or alpha 1 + beta 1 + gamma 2L GABAA receptor subunit DNAs and compared 36Cl- flux with whole-cell, patch-clamp measurements of GABAA receptor function. Both techniques detected a similar modulation of the GABA receptor by ethanol, flunitrazepam, and pentobarbital. The potentiating action of ethanol required the gamma-subunit and was maximal at a concentration of 10 mM. Similar ethanol potentiation was obtained with brief (20 msec) or long (2 sec) applications of GABA. Analysis of data obtained from individual cells expressing alpha 1 beta 1-gamma 2L subunits showed considerable variability in sensitivity to ethanol, particularly with concentrations of 30 and 100 mM. Ethanol potentiated GABA action if the cells were grown on coverslips coated with polylysine, but had no effect on GABAA receptors of cells grown on uncoated coverslips. Thus, ethanol action was influenced by the growth matrix. Taken together, these data indicate that a gamma-subunit is necessary, but not sufficient, for ethanol sensitivity in this cell system. We suggest that posttranslational processing, particularly receptor phosphorylation, may also be important and that stably transfected cells will be useful in elucidating these events.     

Hydrogen-bonding. Part 22. Characterization of soybean oil and prediction of activity coefficients in soybean oil from inverse gas chromatographic data

Previously reported results on twenty-two gaseous compounds with soybean oil as the stationary gas chromatographic phase have been used to characterize soybean oil in terms of dipolarity/polarizability, hydrogen-bond basicity and lipophilicity. The solubility of these gases in soybean oil has been factored into components that show exactly the compound-soybean oil interactions that favor solubility. The same equation used to obtain this information also can be used to predict the gas chromatographic specific retention volume and then the weight-fraction activity coefficient for numerous other compounds on soybean oil, thus leading to predictions of the solubility behavior of these compounds as bulk liquids with soybean oil.     

A comparison of chloride ion diffusion coefficients derived from concentration gradients and non-steady state accelerated ionic migration

A method for electrical indication of the ability of concrete to resist chloride ion penetration was first developed in the USA in the late 1970's. The test method (AASHTO T 277) related chloride ion diffusion to the measurement of electrical charge passed through a test specimen in a relatively short period of time. In this paper, chloride concentration profiles obtained from specimens used in the initial development of the method are used to compute apparent chloride diffusion coefficients, D_app, by application of ionic migration principles. These coefficients are compared to D_app calculated from fitting data obtained from 90-day ponding tests carried out on companion specimens not subjected to application of electrical currents. It is shown that there is a strong linear relationship for conventional concretes between coefficients calculated from chloride concentration gradients produced either by long-term ponding or by accelerated ingress of chloride into the test specimens. Also included in the comparative study are effective diffusion coefficients, D_eff, based on the measurement of specimen resistance and calculated using Einstein's equation. Results indicate that values calculated by any of the techniques yield lower values for diffusion coefficients than those obtained from longer-term ponding. It is shown, however, that rankings of concretes on the basis of diffusion coefficient are similar for both calculated and measured values. Large errors occur in calculated coefficients in cases where anomalies exist in measured chloride gradients. These errors are related to the dependence of calculated diffusion coefficients on chloride concentration ratios. For specialty polymer concretes, mechanisms of penetration of chloride into concrete may be different in the presence of an applied electrical field. These differences may be the result of the short test time in the AASHTO T 277 procedure as well as of the relatively high voltage used. These effects prevent the concrete from reaching the same chloride surface concentration, C_s, as in longer-term (90-day) ponding. Anomalously high D_app valves are computed when the concrete is too resistive or has been surface treated. In these cases, the C_s valves are far greater than those obtained during 90-day ponding.     

The use of a computer tutorial as a replacement for human tuition in a mastery learning strategy

Computer Assisted Learning (CAL) is a traditional activity in tertiary education. Few available CAL programs exhibit user friendliness and most are complex simulation or modelling programs not primarily designed as instructional programs. Authoring languages are designed to enable teachers to write instructional programs without the need to learn computer languages. This investigation reports upon the use of a tutorial program written in the authoring language “STAF2” to replace human tuition as part of a mastery learning experience in undergraduate biology. A similar mastery learning experience, taught identically to both student groups served as a control. All learning was assessed cognitively in terms of Bloom's Taxonomy of Educational Objectives and the results compared between the human-taught and STAF2-taught groups. All learning experiences resulted in the majority of students attaining mastery. The students taught by the STAF2 computer program attained significantly higher scores for retention of knowledge, its application and evaluation when compared with those taught by a human teacher. Whilst there was no significant difference between the groups in terms of comprehension, analysis and synthesis, the mean scores and the percentage of students attaining mastery after computer tuition was higher than the human taught group. The implications of these results are discussed.     

Deblurring subject to nonnegativity constraints when knownfunctions are present with application to object-constrainedcomputerized tomography

The reconstruction of tomographic images is often treated as a linear deblurring problem. When a high-density, man-made metal object is present somewhere in the image field, it is a deblurring problem in which the unknown function has a component that is known except for some location and orientation parameters. We first address general linear deblurring problems in which a known function having unknown parameters is present. We then show how the resulting iterative solution can be applied to tomographic imaging in the presence of man-made foreign objects, and we apply the result, in particular, to X-ray computed tomography imaging used in support of brachytherapy treatment of advanced cervical cancer.     

Distributed Adaptive Algorithms for Optimal Opportunistic Medium Access

We examine threshold-based transmission strategies for distributed opportunistic medium access in a scenario with fairly general probabilistic interference conditions. Specifically, collisions between concurrent transmissions are governed by arbitrary probabilities, allowing for a form of channel capture and covering binary interference constraints as an important special case. We address the problem of setting the threshold values so as to optimize the aggregate throughput utility of the various users, and particularly focus on a weighted logarithmic throughput utility function (Proportional Fairness). We provide an adaptive algorithm for finding the optimal threshold values in a distributed fashion, and rigorously establish the convergence of the proposed algorithm under mild statistical assumptions. Moreover, we discuss how the algorithm may be adapted to achieve packet-level stability with only limited exchange of queue length information among the various users. We also conduct extensive numerical experiments to corroborate the theoretical convergence results.     

Age-related decline of visual processing components in change detection.

Previous research has suggested that an age-related decline in change detection may be due to older adults using a more conservative response criterion. However, this finding may reflect methodological limitations of the traditional change detection design, in which displays are presented continuously until a change is detected. Across 2 experiments, the authors assessed adult age differences in a version of change detection that required a response after each pair of pre- and postchange displays, thus reducing the potential contribution of response criterion. Older adults performed worse than younger adults, committing more errors and requiring a greater number of display cycles for correct detection. These age-related performance declines were substantially reduced after controlling statistically for elementary perceptual speed. Search strategy was largely similar for the 2 age groups, but perceptual speed was less successful in accounting for age-related variance in detectability when a more precise spatial localization of change was required (Experiment 2). Thus, the negative effect of aging in the present tasks lies in a reduction of detection efficiency due largely to processing speed, though some strategy-level effects may also contribute. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting Sea Lamprey (Petromyzon marinus) Ammocoete Habitat Using Geographic Information Systems

The sea lamprey (Petromyzon marinus) is an invasive, parasitic species with a long history of decimating fisheries in the Laurentian Great Lakes. The sea lamprey life cycle consists of stream larval ammocoete, open water parasitic, and adult spawning phases. Population control of sea lamprey is achieved mainly through the application of chemical lampricides that target the sedentary larval stage. The physical characteristics of preferred ammocoete habitat are well defined at the sub-reach scale (< 50 m). We tested whether the spatial distribution of beds of preferred ammocoete habitat depends upon a specific set of geomorphic variables (field-measured slope, and geographic information system (GIS)- derived curvature, radius of curvature, presence of a confluence, and valley wall type). We tested for this relationship at several spatial scales of stream length ranging from 50 m to 300 m, on the East Branch of the Chagrin River, Ohio, USA, a tributary stream to Lake Erie. Of the five geomorphic variables tested, field-measured slope and radius of curvature influence the probability of a stream segment containing preferred habitat at a stream segment length of 50 m. We found no relationships at longer stream segment lengths. GIS-estimated slopes were not sufficiently accurate at such short segment lengths, so the final model included radius of curvature only. These results are applicable to the Empiric Stream Treatment Ranking (ESTR) system, which ranks tributaries for treatment with lampricide based partially on the total amount of preferred ammocoete habitat. GIS-based estimates of the total amount of preferred ammocoete habitat may complement current field-based estimates, or provide a basis for nested sampling designs.     

Individual- and organizational-level consequences of organizational citizenship behaviors: A meta-analysis.

Although one of the main reasons for the interest in organizational citizenship behaviors (OCBs) is the potential consequences of these behaviors, no study has been reported that summarizes the research regarding the relationships between OCBs and their outcomes. Therefore, the purpose of this study is to provide a meta-analytic examination of the relationships between OCBs and a variety of individual- and organizational-level outcomes. Results, based on 168 independent samples (N = 51,235 individuals), indicated that OCBs are related to a number of individual-level outcomes, including managerial ratings of employee performance, reward allocation decisions, and a variety of withdrawal-related criteria (e.g., employee turnover intentions, actual turnover, and absenteeism). In addition, OCBs were found to be related (k = 38; N = 3,611 units) to a number of organizational-level outcomes (e.g., productivity, efficiency, reduced costs, customer satisfaction, and unit-level turnover). Of interest, somewhat stronger relationships were observed between OCBs and unit-level performance measures in longitudinal studies than in cross-sectional studies, providing some evidence that OCBs are causally related to these criteria. The implications of these findings for both researchers and practitioners are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)