Adaptation to Visual Feedback Delay Influences Visuomotor Learning

Computational theory of motor control suggests that the brain continuously monitors motor commands, to predict their sensory consequences before actual sensory feedback becomes available. Such prediction error is a driving force of motor learning, and therefore appropriate associations between motor commands and delayed sensory feedback signals are crucial. Indeed, artificially introduced delays in visual feedback have been reported to degrade motor learning. However, considering our perceptual ability to causally bind our own actions with sensory feedback, demonstrated by the decrease in the perceived time delay following repeated exposure to an artificial delay, we hypothesized that such perceptual binding might alleviate deficits of motor learning associated with delayed visual feedback. Here, we evaluated this hypothesis by investigating the ability of human participants to adapt their reaching movements in response to a novel visuomotor environment with 3 visual feedback conditions—no-delay, sudden-delay, and adapted-delay. To introduce novelty into the trials, the cursor position, which originally indicated the hand position in baseline trials, was rotated around the starting position. In contrast to the no-delay condition, a 200-ms delay was artificially introduced between the cursor and hand positions during the presence of visual rotation (sudden-delay condition), or before the application of visual rotation (adapted-delay condition). We compared the learning rate (representing how the movement error modifies the movement direction in the subsequent trial) between the 3 conditions. In comparison with the no-delay condition, the learning rate was significantly degraded for the sudden-delay condition. However, this degradation was significantly alleviated by prior exposure to the delay (adapted-delay condition). Our data indicate the importance of appropriate temporal associations between motor commands and sensory feedback in visuomotor learning. Moreover, they suggest that the brain is able to account for such temporal associations in a flexible manner

First Report of Chenodeoxycholic Acid-Substituted Dyes Improving the Dye Monolayer Quality in Dye-Sensitized Solar Cells

Chenodeoxycholic acid (CDCA) is the most used antiaggregation additive in dye-sensitized solar cells since its introduction to the field in 1993. However, effective suppression of dye aggregation comes at the cost of reduced dye loading, a lower open-circuit voltage, and limited control of dye/additive distribution when cosensitizing with free CDCA. To combat this, herein, a novel dye design concept that uses the covalent attachment of a CDCA moiety to triarylamine sensitizers is reported. The CDCA substituents do not affect the photophysical or electrochemical properties of the sensitizers but have a positive effect on the photovoltaic performance with [Cu+/2+(tmby)(2)](TFSI)(1/2) electrolyte (tmby = 4,4 ',6,6 '-tetramethyl-2,2 '-bipyridine, TFSI = bis(trifluoromethanesulfonyl)imide). By ensuring a one-to-one ratio of dye and CDCA, paired with isotropic distributions of each component, this approach results in a higher-quality dye monolayer. Compared with the reference system, the novel approach reported herein gives a higher open-circuit voltage and power conversion efficiency (PCE). The best device is fabricated with the dye C-6-CDCA, delivering a PCE of 6.84% (8 mu m TiO2, 1 mm CDCA, J(SC) = 8.64 mA cm(-2), V-OC = 1007 mV, and FF = 0.77)

Levers of logistics service providers’ efficiency in urban distribution

This paper identifies the most important factors that influence the productivity of the urban fleet of a Logistics Service Provider (LSP). Through a regression analysis on a dataset from distribution warehouses of a single LSP, three main levers are shown to have significant impacts on productivity, namely the network design, the vehicle loading strategy, and the business environment wherein the operations are carried out. This paper contributes to bridge the gap about the lack of works addressing the efficiency of LSPs operating in urban areas, by performing a detailed empirical analysis instead of taking an aggregated company perspective