A confidence level algorithm for the determination of absolute configuration using vibrational circular dichroism or raman optical activity

Spectral comparison is an important part of the assignment of the absolute configuration (AC) by vibrational circular dichroism (VCD), or equally by Raman optical activity (ROA). In order to avoid bias caused by personal interpretation, numerical methods have been developed to compare measured and calculated spectra. Using a neighbourhood similarity measure, the agreement between a computed and measured VCD or ROA spectrum is expressed numerically to introduce a novel confidence level measure. This allows users of vibrational optical activity (VOA) techniques (VCD and ROA) to assess the reliability of their assignment of the AC of a compound. To that end, a database of successful AC determinations is compiled along with neighbourhood similarity values between the experimental spectrum and computed spectra for both enantiomers. For any new AC determination, the neighbourhood similarities between the experimental spectrum and the computed spectra for both enantiomers are projected on the database allowing an interpretation of the reliability of their assignment

Development of methodology to assign absolute configurations using vibrational circular dichroism

De kennis van de 3D structuur van actieve bestanddelen van chirale medicijnen is zeer belangrijk, aangezien stereo-isomeren dikwijls een verschillende activiteit vertonen. Er zijn meerdere technieken beschikbaar om deze Absolute Configuratie te bepalen (eenkristal x-straal diffractie bijv.). Een nieuwe methode die sterk in opmars is en heel wat voordelen biedt is gebaseerd op het vibrationeel circulair dichroïsme (VCD). Het VCD fenomeen is een gevolg van de optische activiteit van een medium (chirale molecule in oplossing bijv.) en is de differentiële absorptie van circulair gepolariseerd infrarood straling. In een VCD spectrum zit de stereochemische informatie van de chirale molecule vervat, aangezien de moleculen die elkaars spiegelbeeld zijn VCD intensiteiten hebben van gelijke intensiteit maar met tegengesteld teken. Om deze stereochemische informatie echter de extraheren wordt er gebruikt gemaakt van kwantum chemische berekeningen om de VCD spectra van moleculen met gekende stereochemie te simuleren, zodat deze dan kunnen worden vergeleken met experimentele spectra. Op basis van de overeenkomst tussen experimentele en theoretische spectra kan de absolute configuratie worden toegewezen. In dit proefschrift is de sterkte van deze techniek bevestigd; 21 chirale moleculen uit de farmaceutische industrie (Johnson & Johnson) en organische synthese zijn met succes onderzocht. Een belangrijke conclusie is dat deze methode mits de nodige voorzorgen kan worden toegepast in een industriële omgeving en krachtiger kan zijn dan eenkristal x-straal diffractie

Testing the structure and process of personality using ambulatory assessment data : an overview of within-person and person-specific techniques

In the present article, we discuss the potential of ambulatory assessment for an idiographic study of the structure and process of personality. To this end, we first review important methodological issues related to the design and implementation of an ambulatory assessment study in the personality domain, including methods of ambulatory assessment, frequency of measurement and duration of the study, ambulatory assessment scales and questionnaires, participant selection, training and motivation, and ambulatory assessment hard- and software. Next, we provide a detailed outline of available analytical approaches that can be used to analyze the intensive longitudinal data generated by an ambulatory assessment study. By doing this, we hope to familiarize personality scholars with these methods and to provide guidance for their use in the field of personality psychology and beyond

Mind the level: problems with two recent nation-level analyses in psychology

Two recent articles (both published in Psychological Science) rely on nation-level data to address questions about psychological processes: Oishi and Diener (2014), referred to here as “OD,” and Hershfield et al. (2014), referred to as “HBW.” In our opinion, both articles contain problems with regard to the use and interpretation of nation-level data. The problems are (1) the failure to account for the statistical dependence of countries within regions, (2) the use of nation-level data with questionable reliability, and (3) a confusion between individual and national levels of analysis

The role of stimulus-driven versus goal-directed processes in fight and flight tendencies measured with motor evoked potentials induced by Transcranial Magnetic Stimulation

This study examines two contrasting explanations for early tendencies to fight and flee. According to a stimulus-driven explanation, goal-incompatible stimuli that are easy/difficult to control lead to the tendency to fight/flee. According to a goal-directed explanation, on the other hand, the tendency to fight/flee occurs when the expected utility of fighting/fleeing is the highest. Participants did a computer task in which they were confronted with goal-incompatible stimuli that were (a) easy to control and fighting had the highest expected utility, (b) easy to control and fleeing had the highest expected utility, and (c) difficult to control and fleeing and fighting had zero expected utility. After participants were trained to use one hand to fight and another hand to flee, they either had to choose a response or merely observe the stimuli. During the observation trials, single-pulse Transcranial Magnetic Stimulation (TMS) was applied to the primary motor cortex 450 ms post-stimulus onset and motor evoked potentials (MEPs) were measured from the hand muscles. Results showed that participants chose to fight/flee when the expected utility of fighting/fleeing was the highest, and that they responded late when the expected utility of both responses was low. They also showed larger MEPs for the right/left hand when the expected utility of fighting/fleeing was the highest. This result can be interpreted as support for the goal-directed account, but only if it is assumed that we were unable to override the presumed natural mapping between hand (right/left) and response (fight/flight)

Psychopathology and positive emotions in daily life

In this short review, we describe recent trends from Ecological Momentary Assessment (EMA) research investigating positive affect (PA) in relation to mood disorders. Aside from notable exceptions (e.g. mania), most mood disorders involve relatively lower levels of PA in daily life, often combined with a larger level of variability in PA. In reaction to positive events, studies show a puzzling ‘mood brightening’ effect in individuals with mood disorder symptoms that suggests hyper responsiveness to real-life rewards. Studies into anhedonia (i.e. lack of, or lower levels of PA) suggest that high-arousal PA and anticipatory PA are potential targets for intervention. Despite PA-focused EMA-interventions bear promises of greater therapeutic effectiveness, so far, these promises have not materialized yet