Proportional Sampling in Life Length Studies

In studying electron tube life, measuring the life of a tube in service in a system whose age is T amounts to lifelength proportional sampling. The problems of estimating mean life from such data are considered for finite T and for “equilibrium” (large T). Several variations on the straight-forward life-biased sampling plan which are avilable to the experimenter are mentioned and conditions are found under which these other sampling schemes would be better than the life-proportional scheme. Particular attention is paid to the gamma and Weibull families of distributions. Other applications of these results are discussed.     

Signal and noise transfer in spatiotemporal quantum-based imaging systems

Fourier-based transfer theory is extended into the temporal domain to describe both spatial and temporal noise processes in quantum-based medical imaging systems. Lag is represented as a temporal scatter in which the release of image quanta is delayed according to a probability density function. Expressions describing transfer of the spatiotemporal Wiener noise power spectrum through quantum gain and scatter processes are derived. Lag introduces noise correlations in the temporal domain in proportion to the correlated noise component only. The effect of lag is therefore dependent on both spatial and temporal physical processes. A simple model of a fluoroscopic system shows that image noise is reduced by a factor that is similar to Wagner's information bandwidth integral, which depends on the temporal modulation transfer function.     

More on the psychology of false confessions.

Responds to comments by J. T. McCann (see record 1998-00122-001) and A. Reifman (see record 1998-00122-002) concerning S. M. Kassin's article (see record 1997-07781-003) on the psychology of false confessions. It is stated that these commentaries offer interesting perspectives with which to expand what is currently known about the psychology of confession evidence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ecological momentary assessment in a behavioral drinking moderation training program.

We assessed predictors of self-reported excessive drinking (>5 drinks) in a sample of heavy drinkers. Participants were randomly assigned to moderation training or a waiting-list control condition. They were trained in ecological momentary assessment (EMA) involving self-monitoring of drinking and other variables on a small hand-held computer, the electronic diary (ED). During the 8-week study, participants were compliant in their use of the ED for both random prompts and the entry of data related to specific drinking episodes. Generalized estimating equations were used to fit models involving predictors related to past history of drinking, aspects of the training program, drinking restraint, and episode-specific mood. The models indicated robust predictors of decreased and increased drinking. Our results suggest that EMA is a useful methodology for assessing drinking and related behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Negative Affect and Smoking Lapses: A Prospective Analysis.

Relapse is a central problem in smoking treatment. Data collected at the time of relapse episodes indicate that stress and negative affect (NA) promote relapse, but retrospective data are potentially biased. The authors performed a prospective analysis of stress and NA prior to initial lapses in smokers (N = 215). Day-to-day changes in stress (daily negative and positive events and Perceived Stress Scale scores) and NA (multiple momentary affect ratings) did not predict lapse risk on the following day. However, within the lapse day itself, NA was already significantly increasing hours before lapses, but only for episodes attributed to stress or bad mood. Thus, rapid increases in NA, but not slow-changing shifts in stress and NA, were associated with relapse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Smoking patterns and dependence: Contrasting chippers and heavy smokers.

The authors used ecological momentary assessment to contrast smoking patterns among chippers (CHs; n = 26)--smokers who smoke despite an apparent absence of tobacco dependence--with those seen in heavy smokers (HSs; n = 28). Smoking and nonsmoking settings (activity, mood, etc.) were assessed by means of electronic diary. CHs were not social smokers; like HSs, they smoked half their cigarettes while alone. When smoking, CHs' urge levels equaled those of HSs; between cigarettes, CHs had few urges, whereas HSs reported moderate urges. CHs' smoking was particularly associated with indulgent activities: relaxation, socializing, eating, and drinking alcohol. Outside of these indulgent settings, CHs' (but not HSs') smoking was associated with negative affect. In idiographic analyses, CHs' smoking was under much stronger stimulus control than was that of HSs. The authors propose that the disappearance of stimulus control over use is a characteristic of dependence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cesium-137 contamination of soils in settlements of Leningrad oblast and assessment of data accumulated after the Chernobyl accident

The results of works performed in 2007 and 2008 to determine the contamination density (CD) of soil with ¹³⁷Cs and its depth distribution in 45 settlements of the Volosovo and Kingisepp raions of Leningrad oblast, affected by the Chernobyl accident, are reported. With the lognormal distribution of CD values assumed, the confidence ranges for the CD values averaged for specific settlements were estimated on the basis of the results of the above-mentioned works and of the whole set of data accumulated by now. The shortcomings of the Methodical Recommendations of 1990 as applied to the contamination conditions characteristic of Leningrad oblast are noted. In 35 of the 45 settlements surveyed, the volume of data accumulated by now is insufficient for making substantiated management and legal decisions. One of possible ways to make the studies less labor-consuming within the framework of the statistical model used is discussed.     

Modeling Discoloration in Potable Water Distribution Systems

Discoloration of potable water supplied to customer taps is one of the biggest causes of water quality related customer complaints. At present, understanding of the fundamental processes that cause discoloration is limited and the modeling of events unfeasible. This paper describes the development, verification, and validation of a novel cohesive transport modeling approach to simulate discoloration within distribution systems. The model is based on the principal that strength characteristics of fine particulate material accumulated at the pipe walls are conditioned by the shear stress of the usual daily hydraulics. Discoloration occurs when the flow through the systems changes, exceeding the peak daily value. Fieldwork results from two sites are presented in detail: Site 1 demonstrates model application including sensitivity and parameter dependence, while data from Site 2 is used to investigate the hypothesis that daily hydraulic forces condition the material layers within the pipes. Model simulations are also presented for a selection of other field sites to demonstrate the wider applicability of the model.     

The Morning After: Limit Violations and the Self-Regulation of Alcohol Consumption.

The authors examined whether the reciprocal relationship between alcohol consumption and distress unfolded over time in 2 samples of social drinkers. Participants monitored their alcohol intake and their cognitive and emotional responses to that drinking on hand-held computers. On mornings after drinking, those who had violated their self-imposed limits the day before reported more guilt, even after controlling for acute negative symptoms of drinking and amount consumed. Reciprocally, guilt led to poorer self-regulation of alcohol intake: Greater distress over alcohol consumption was linked to more intake, intoxication, and more limit violations. Individual differences moderated the relationships among limit violations, distress, and drinking. Consistent with the limit violation effect, violating a limit produced distress over consumption among social drinkers, and they responded to that distress by drinking more. (PsycINFO Database Record (c) 2010 APA, all rights reserved)