Delay and reward choice in ADHD: An experimental test of the role of delay aversion.

Children with attention deficit/hyperactivity disorder (ADHD) choose smaller sooner (SS) over larger later (LL) rewards more than controls. Here we assess the contributions of impulsive drive for immediate rewards (IDIR) and delay aversion (DAv) to this pattern. We also explore the characteristics of, and the degree of familiality in, ADHD SS responders. We had 360 ADHD probands; 349 siblings and 112 controls (aged between 6 to 17 years) chose between SS (1 point after 2 s) and LL reward (2 points after 30 s) outcomes on the Maudsley Index of Delay Aversion (Kuntsi, Oosterlaan, & Stevenson, 2001): Under one condition SS choice led to less overall trial delay under another it did not. ADHD participants chose SS more than controls under both conditions. This effect was larger when SS choice reduced trial delay. ADHD SS responders were younger, had lower IQ, more conduct disorder and had siblings who were more likely to be SS responders themselves. The results support a dual component model in which both IDIR and DAv contribute to SS choice in ADHD. SS choice may be a marker of an ADHD motivational subtype. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

In Situ Silicone Tube Microextraction: A New Method for Undisturbed Sampling of Root-exuded Thiophenes from Marigold (<Emphasis Type="Italic">Tagetes erecta</Emphasis> L.) in Soil

The difficulties of monitoring allelochemical concentrations in soil and their dynamics over time have been a major barrier to testing hypotheses of allelopathic effects. Here, we evaluate three diffusive sampling strategies that employ polydimethylsiloxane (PDMS) sorbents to map the spatial distribution and temporal dynamics of root-exuded thiophenes from the African marigold, Tagetes erecta. Solid phase root zone extraction (SPRE) probes constructed by inserting stainless steel wire into PDMS tubing were used to monitor thiophene concentrations at various depths beneath marigolds growing in PVC pipes. PDMS sheets were used to map the distribution of thiophenes beneath marigolds grown in thin glass boxes. Concentrations of the two major marigold thiophenes measured by these two methods were extremely variable in both space and time. Dissection and analysis of roots indicated that distribution of thiophenes in marigold roots also was quite variable. A third approach used 1 m lengths of PDMS microtubing placed in marigold soil for repeated sampling of soil without disturbance of the roots. The two ends of the tubing remained out of the soil so that solvent could be washed through the tubing to collect samples for HPLC analysis. Unlike the other two methods, initial experiments with this approach show more uniformity of response, and suggest that soil concentrations of marigold thiophenes are affected greatly even by minimal disturbance of the soil. Silicone tube microextraction gave a linear response for α-terthienyl when maintained in soils spiked with 0–10 ppm of this thiophene. This method, which is experimentally simple and uses inexpensive materials, should be broadly applicable to the measurement of non-polar root exudates, and thus provides a means to test hypotheses about the role of root exudates in plant-plant and other interactions.     

Future technology on the flight deck: assessing the use of touchscreens in vibration environments

Abstract

Use of touchscreens in the flight deck has been steadily increasing, however, their usability may be severely impacted when turbulent conditions arise. Most previous research focusses on using touchscreens in static conditions; therefore, this study assessed touchscreen use whilst undergoing turbulent representative motion, generated using a 6-axis motion simulator. Touchscreens were tested in centre, side and overhead positions, to investigate how turbulence affected: (1) error rate, movement times and accuracy, (2) arm fatigue and discomfort. Two touchscreen technologies were compared: a 15” infra-red and a 17.3” projected capacitive touchscreen with force sensing capability. The potential of the force sensing capability to minimise unintentional interactions was also investigated. Twenty-six participants undertook multi-direction tapping (ISO 9241; ISO 2010 ISO (International Organization for Standardization). 2010. “ISO 9241 Ergonomics of Human System Interaction – Part 210: Human-centred Design for Interactive Systems.” Tech. Rep. Switzerland. [Google Scholar]) and gesture tasks, under four vibration conditions (control, light chop, light turbulence and moderate turbulence). Error rate, movement time and workload increased and usability decreased significantly, with screen position and increasing turbulence level.

Practitioner Summary: This study evaluated the use of infra-red and projected capacitive touchscreen technologies using multi-directional tapping and gesture tasks, whilst being subjected to different levels of turbulence representative motion. Performance degraded significantly with increasing turbulence level and touchscreen location. This has implications for future flight deck design.     

Emotion experience, expression, and regulation in Alzheimer's disease.

Alzheimer's disease (AD) is associated with intact experience but abnormal expression of emotion. Because emotion regulation is important in determining levels of experienced and expressed emotion, individuals with AD and control participants were asked to watch film clips under conditions of spontaneous expression, suppression, or amplification of emotion. Both groups had difficulties with behavioral amplification that were related to performance on a measure of theory of mind. However, intentional use of suppression was intact even for those with AD, consistent with models of aging that regard some emotion control processes as being relatively more automatic in older adulthood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Appraisals, coping, and stress in breast cancer screening: A longitudinal investigation of causal structure.

The cognitive-appraisal model of R. S. Lazarus and S. Folkman (1984) is one of the most prominent theories of stress. As integral elements in this model, appraisal and coping have both been proposed as mediators of the stress response. The purpose of this study was to test the predictive power of the theoretical model based on 2 competing formulations using structural equation modeling techniques. One conceptual model proposed that coping influences stress through appraisal; the other proposed that appraisals impact on stress via coping. 506 women (aged 50+ yrs) undergoing breast cancer screening completed measures of appraisal, coping, and stress. Support was found for both hypothesized causal structures. The implications of these findings are discussed in terms of Lazarus's theoretical perspective. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Model Studies of NOx Storage and Sulphur Deactivation of NOx Storage Catalysts

The storage of NO _x under lean conditions in model NO _x storage catalysts as well as the deactivation by sulphur have been studied. We find that NO₂ plays an important role in the storage mechanism as an oxidising agent. Two different mechanisms for this are discussed: the formation of surface peroxides and the oxidation of nitrites to nitrates. FTIR studies show that NO _x is stored as surface nitrates. The sulphur deactivation is found to be more severe when SO₂ is added during the rich phase than when SO₂ is added during the lean period. FTIR shows the formation of bulk sulphates both under lean and rich conditions.     

Partitioning and speciation of chromium, copper, and arsenic in CCA-contaminated soils: influence of soil composition

This study focused on the influence of soil composition and physicochemical characteristics on the retention and partitioning of Cu, Cr and As in nine chromated copper arsenate (CCA) artificially contaminated soils. A statistical mixture design was used to set up the number of soils and their respective composition. Sequential extraction and modified solvent extraction were used to assess Cu and Cr partitioning and As speciation [As(III) or As(V)]. It was found that peat had a strong influence on CEC (232 meq/100 g), on buffer capacity and on Cu and Cr retention, whereas kaolinite's contribution to the CEC was minor (38 meq/100 g). Average metal retention in mineral soils was low (58% for Cu and 23% for Cr) but increased dramatically in highly organic soils (96% for Cu and 78% for Cr). However, both organic and mineral soils demonstrated a very high sorption of added As (71-81%). Levels of Cu and Cr in a soluble or exchangeable form (F1) in highly organic soils were very low, whereas the levels strongly bound to organic matter were much higher. Conversely, in mineral soils, 47% of Cu and 18% of Cr were found in F1. As a result, Cr and Cu in moderately and highly organic contaminated soils were present in less mobile and less bioavailable forms, whereas in mineral soils, the labile fraction was higher. The modified method used for selective determination of mineral As species in CCA-contaminated soils was found to be quantitative and reliable. Results revealed that arsenic was principally in the pentavalent state. Nevertheless, in organic soils, arsenite was found in significant proportions (average value of 29% in highly organic soils). This indicates that some reduction of arsenate to arsenite occurred since the original species in CCA is As(V).