Naltrexone alteration of the nicotine-induced EEG and mood activation response in tobacco-deprived cigarette smokers.

The neural mechanisms contributing to the arousal-eliciting actions of smoking and nicotine involve multiple neurotransmitter systems. The current study examined the role of opioid neurotransmission in modulating the neuroelectric- and mood-activating response to acute nicotine administration in overnight tobacco-deprived smokers. In a randomized, double-blind, placebo-controlled design involving 18 (10 male, 8 female) overnight tobacco-abstinent smokers, spectrally analyzed electroencephalographic (EEG) activity and subjective reports of mood, euphoria, and smoking withdrawal were assessed in response to nicotine gum (4 mg) after pretreatment with placebo or with 50 mg of the opioid antagonist naltrexone. In addition to reducing withdrawal symptoms and increasing euphoria ratings, as well as subjective alertness in male participants, nicotine induced an EEG arousal response consisting of diffuse slow wave (delta, theta) amplitude reductions, frontal fast alpha wave amplitude increments, and elevations in beta wave amplitude, which were greater in female than in male smokers. Naltrexone attenuated the alerting and euphoric actions of nicotine but did not affect nicotine's ameliorating effects on withdrawal symptoms. Nicotine-induced frontal reductions in delta and global reductions in theta were prevented by naltrexone pretreatment, as were increases in anterior recordings of relative fast alpha. These findings suggest that the opioid system is involved in nicotine-induced subjective and neuroelectric arousal and implicate opioid-cholinergic interactions in the elicitation of these arousal responses to nicotine. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of Hydraulic Fracture with Inflated Dislocation Moving Within a Semi-infinite Medium

Hydraulic fracturing is accompanied by a change in pore fluid pressure. As a result,this may be conveniently represented as inflated dislocation moving within a semi-infinite medium. Theory is developed to describe the pore pressures that build up around an inflated volumetric dislocation migrating within a saturated porous-elastic semi-infinite medium as analog to hydraulic fracturing emplacement. The solution is capable of evaluating the system behavior of both constant fluid pressure and zero flux surface conditions through application of a superposition. Characterization of horizontal moving dislocation processes is conducted as an application of these techniques. Where the mechanical and hydraulic parameters are defined,a priori,type curve matching of responses may be used to evaluate emplacement location uniquely. Pore pressure response elicited at a dilation,subject to pressure control is of interest in representing hydraulic fracturing where leak-off is an important component. The effect of hydraulic fracturing on fracture fluid pressure is evaluated in a poroelastic hydraulic fracture model utilizing dislocation theory. A minimum set of dimensionless parameters are defined that describe the system. Pore fluid pressures recorded during hydraulic fracturing of a well in the San Joaquin Valley of Central California is examined using the proposed model. The estimated geometry of the hydraulic fracture is matched with reasonable fidelity with the measured data.     

Numerical and Experimental Performance Evaluation of the 3-Stage FROSTY Supercooled Cloud Collector

An evaluation of the collection characteristics of a new multistage cascade inertial impactor designed for size-resolved cloud drop collection has been performed. The FROSTY supercooled cloud collector is intended for the collection of supercooled cloud drops in a winter environment in three independent size fractions with stage 50% cut diameters of 15 θ m, 10 θ m, and 4 θ m. Two approaches were selected for the evaluation of the collector. Numerical simulations provided a visualization of the airflow patterns and drop trajectories through the collector while experimental laboratory calibration provided a quantitative analysis of true collection performance. For each of these methods, 50% cut diameters, efficiency curves, and wall losses for each stage of the collector were determined. Collection characteristics were determined experimentally by introducing fluorescein-tagged monodisperse drops into the collector and analyzing collection patterns by fluorescence. The experimental measurements at laboratory conditions indicated 50% cut diameters of 19.0, 11.5, and 5.0 θ m for the three stages. Adjusted for operation at collector design conditions, the 50% cut diameters were 17.0, 10.5, and 4.5 θ m. Numerical modeling of the airflow patterns and drop trajectories through the collector was performed with the commercially available Computational Fluid Dynamics (CFD) software package FLUENT. Trajectory simulations based on the average continuous phase (air) velocity field as well as trajectory simulations which included the effects of statistically derived turbulent velocity fluctuations on drop motion were performed. Comparisons between the numerical and experimental work indicated that the inclusion of turbulent fluctuation effects on drop motion provided much better agreement with experimental observations than trajectories based solely on average flow field velocities. However, the use of continuous phase velocity fluctuations also produced unrealistic losses to wall surfaces for small drop sizes. Despite this shortcoming, numerically derived 50% cut diameters and overall collection efficiency curve shapes for drop trajectories including turbulent velocity fluctuations agreed reasonably well with experimental observations.     

Integration of chaos theory and mathematical models in building simulation: Part II: Conceptual frameworks

Current mathematical models in building research have been limited in most studies to linear dynamics systems. A literature review of past studies investigating chaos theory approaches in building simulation models suggests that as a basis chaos model is valid and can handle the increasing complexity of building systems that have dynamic interactions among all the distributed and hierarchical systems on the one hand, and the environment and occupants on the other. The review also identifies the paucity of literature and the need for a suitable methodology of linking chaos theory to mathematical models in building design and management studies. This study is broadly divided into two parts and presented in two companion papers. Part (I), published in the previous issue, reviews the current state of the chaos theory models as a starting point for establishing theories that can be effectively applied to building simulation models. Part (II) develop conceptual frameworks that approach current model methodologies from the theoretical perspective provided by chaos theory, with a focus on the key concepts and their potential to help to better understand the nonlinear dynamic nature of built environment systems. Case studies are also presented which demonstrate the potential usefulness of chaos theory driven models in a wide variety of leading areas of building research. This study distills the fundamental properties and the most relevant characteristics of chaos theory essential to (1) building simulation scientists and designers (2) initiating a dialogue between scientists and engineers, and (3) stimulating future research on a wide range of issues involved in designing and managing building environmental systems.     

Marking effects in Pavlovian trace conditioning.

[Correction Notice: An erratum for this article was reported in Vol 13(3) of Journal of Experimental Psychology: Animal Behavior Processes (see record 2008-10750-001). The last sentence in the second paragraph of the Discussion on page 128 should read as follows: "A second possibility is that in the marked ITI group, the marking of irrelevant events in the middle of the intertrial interval promoted associations between those events and food, which then interfered with the learning of an association between SI and food."] In four experiments we investigated pigeons' acquisition of a successive discrimination with a trace autoshaping procedure. The conditioned stimuli were 5-s presentations of colored key lights, one of which was followed by food after a 5-s delay. In Experiment 1, which used spatially defined cues, we found that acquisition of differential responding to the reinforced cue was facilitated when a brief flash of light immediately followed both reinforced and nonreinforced cues. Experiment 2 found a similar enhancement by the added light flash in a purely visual discrimination. Experiment 3 found that the flash facilitated learning only when presented immediately after the discriminative cues, and not when it occurred immediately before the cues or at the time of reinforcement. A fourth experiment found this facilitation effect only when the flash and reinforcement occurred on the same trial. These results are interpreted in terms of marking: The flash enhanced learning because it triggered a backward scan through recent memory to search for possible predictors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Digital Underlife in the Networked Writing Classroom

This article offers a theoretical framework for ‘digital underlife’: the distal and potentially transgressive discursive activities proliferated by emerging technologies. Digital underlife is an adaptation of sociologist Erving Goffman's concept of underlife, which figured centrally in Robert Brooke's well-known study of writing activity in 1988. As emerging digital technologies fray the communicative bounds of traditional sites for teaching and learning, such as the classroom and the conference hall, we are confronted anew with a complex array of possibilities for giving and getting attention. Drawing on the work of Charles Moran and Richard Lanham, this article calls for a more receptive disposition toward the productive dimensions of digital underlife. The article promotes a stance that imagines productive digital underlife to be intrinsic to curricula that combine digital writing activity and rhetorical education, rather than short-selling digital underlife as mere distraction, as an impediment to learning, or worse, attempting to banish it altogether.