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BackgroundEver since Gay-Lussac's time, the alcoholic strength by volume (% vol) has been determined by using densimetric measurements. The typical reference procedure involves distillation followed by pycnometry, which is comparably labour-intensive and therefore expensive. At present, infrared (IR) spectroscopy in combination with multivariate regression is widely applied as a screening procedure, which allows one to determine alcoholic strength in less than 2 min without any sample preparation. The disadvantage is the relatively large investment for Fourier transform (FT) IR or near-IR instruments, and the need for matrix-dependent calibration. In this study, we apply a much simpler device consisting of a patented multiple-beam infrared sensor in combination with a flow-through cell for automated alcohol analysis, which is available in a portable version that allows for on-site measurements.ResultsDuring method validation, the precision of the infrared sensor was found to be equal to or better than densimetric or FTIR methods. For example, the average repeatability, as determined in 6 different wine samples, was 0.05% vol and the relative standard deviation was below 0.2%. Accuracy was ensured by analyzing 260 different alcoholic beverages in comparison to densimetric or FTIR results. The correlation was linear over the entire range from alcohol-free beers up to high-proof spirits, and the results were in substantial agreement (R = 0.99981, p < 0.0001, RMSE = 0.279% vol). The applicability of the device was further proven for the analysis of wines during fermentation, and for the determination of unrecorded alcohol (i.e. non-commercial or illicit products).ConclusionsThe flow-through infrared device is much easier to handle than typical reference procedures, while time-consuming sample preparation steps such as distillation are not necessary. Therefore, the alcoholic strength can be economically and quickly controlled (requiring less than 60 s per sample). The device also gives the opportunity for mobile on-site control in the context of labelling control of wine, beer and spirits, the process monitoring of fermentations, or the evaluation of unrecorded alcohols.

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Representative design refers to the idea that experimental stimuli should be sampled or designed such that they represent the environments to which measured constructs are supposed to generalize. In this article we investigate the role of representative design in achieving valid and reliable psychological assessments, by focusing on a widely used behavioral measure of risk taking-the Balloon Analogue Risk Task (BART). Specifically, we demonstrate that the typical implementation of this task violates the principle of representative design, thus conflicting with the expectations people likely form from real balloons. This observation may provide an explanation for the previously observed limitations in some of the BART's psychometric properties (e.g., convergent validity with other measures of risk taking). To experimentally test the effects of improved representative designs, we conducted two extensive empirical studies (N = 772 and N = 632), finding that participants acquired more accurate beliefs about the optimal behavior in the BART due to these task adaptions. Yet, improving the task's representativeness proved to be insufficient to enhance the BART's psychometric properties. It follows that for the development of valid behavioral measurement instruments-as are needed, for instance, in functional neuroimaging studies-our field has to overcome the philosophy of the "repair program" (i.e., fixing existing tasks). Instead, we suggest that the development of valid task designs requires novel ecological assessments, aimed at identifying those real-life behaviors and associated psychological processes that lab tasks are supposed to capture and generalize to.

MDMA ("ecstasy") is widely used as a recreational drug, although there has been some debate about its neurotoxic effects in humans. However, most studies have investigated subjects with heavy use patterns, and the effects of transient MDMA use are unclear. In this review, we therefore focus on subjects with moderate use patterns, in order to assess the evidence for harmful effects. We searched for studies applying neuroimaging techniques in man. Studies were included if they provided at least one group with an average of <50 lifetime episodes of ecstasy use or an average lifetime consumption of <100 ecstasy tablets. All studies published before July 2015 were included. Of the 250 studies identified in the database search, 19 were included. There is no convincing evidence that moderate MDMA use is associated with structural or functional brain alterations in neuroimaging measures. The lack of significant results was associated with high methodological heterogeneity in terms of dosages and co-consumption of other drugs, low quality of studies and small sample sizes.