Color appearance of afterimages compared to the chromatic adaptation to illumination

The color appearance of negative afterimages was measured by the elementary color naming method, and the results were compared with those obtained by the two‐room technique. Twenty adapting stimuli were presented on a display sequentially. Subjects first assessed the color appearance of the stimuli. After looking at the adapting stimulus for 10 seconds, the subjects assessed color of the afterimage. Apparent hue of the afterimage was in general not opponent color to the adapting color. The relation between the adapting stimuli and the afterimages was analyzed by the angle difference Δθ, when apparent hues are expressed by the angles of the points on the polar diagram of the opponent color theory. The relation relationship of Δθ to the angle of the adapting color θ_ing was quite similar to the results obtained by the two‐room technique, implying that the chromatic adaptation shown by the afterimage also occurs in the brain rather than in the retina.     

Advanced factor analysis of spatial distributions of PM2.5 in the eastern United States

This work analyzes PM2.5 24-h average concentrations measured every third day at over 300 locations in the eastern United States during 2000. The non-negative factor analytic model, Positive Matrix Factorization, has been enhanced by modeling the dependence of PM2.5 concentrations on temperature, humidity, pressure, ozone concentrations, and wind velocity vectors. The model comprises 12 general factors, augmented by 5 urban-only factors intended to represent excess concentration present in urban locations only. The computed factor components or concentration fields are displayed as concentration maps, one for each factor, showing how much each factor contributes to the average concentration at each location. The factors are also displayed as flux maps that illustrate the spatial movement of PM2.5 aerosol, thus enabling one to pinpoint potential source areas of PM2.5. The quality of the results was investigated by examining how well the model reproduces especially high concentrations of PM2.5 on specific days at specific locations. Delimiting the spatial extent of all such factors that exhibit a clear regional maximum surrounded by an almost-zero outer domain lowered the uncertainty in the computed results.     

Crystallisation of palm olein under the influence of sucrose esters

This work studied the effects of three sucrose esters (S170, P170 and L195) on the crystallisation of palm olein (PO). The effect of the emulsifiers on the crystallisation behaviour, crystallisation curves, microstructure and polymorphism was investigated. Both S170 and P170 accelerated the early stages, via template effects, but suppressed the later stages of PO crystallisation. The effect on the latter stages was stronger with P170 than S170. In contrast, L195 suppressed PO crystallisation at all time points. Through DSC, S170 and P170 only associated with the high-melting fraction of PO whereas L195 showed little influence. All SEs exhibited no effect on polymorphism. S170 and P170 greatly reduced PO crystal size but increased crystal number while the L195 increased the crystal size but decreased the crystal number especially at low concentration. Overall, S170, P170 and L195 influence PO crystallisation kinetics but the effect was dependent on the emulsifier concentration.