Dynamic Amplification of Optical Signals by Photorefractive Ferroelectric Liquid Crystals

In this chapter, the photorefractive effect in photoconductive ferroelectric liquid crystal blends is described. A blend of liquid crystals that form chiral smectic C phase and photoconductive compounds shows the photorefractive effect. The ferroelectric liquid crystal blends containing a photoconductive chiral compound were found to exhibit a gain coefficient of over 1200 cm-1 and the response time of sub-millisecond. Using the blend, real-time dynamic amplification of an optical image signal of over 30 fps was demonstrated

Greater Disruption Due to Failure of Inhibitory Control on an Ambiguous Distractor

Considerable evidence indicates that a stimulus that is subthreshold, and thus consciously invisible, influences brain activity and behavioral performance. However, it is not clear how subthreshold stimuli are processed in the brain. We found that a task-irrelevant subthreshold coherent motion led to a stronger disturbance in task performance than did suprathreshold motion. With the subthreshold motion, activity in the visual cortex measured by functional magnetic resonance imaging was higher, but activity in the lateral prefrontal cortex was lower, than with suprathreshold motion. These results suggest that subthreshold irrelevant signals are not subject to effective inhibitory control

Cross-modal effect between taste and shape controlled by curvature entropy

In recent years, cross-modal effects in which perceptions interact with each other have been drawing attention. In the case of the cross-modal effect between vision and taste, the effect of the angularity of shapes on taste has been widely studied while there has been little research on the other features of shapes. Previous studies have shown that the emotional valence arisen from visual perception causes the cross-modal effect between vision and taste. Therefore, this study focuses on the complexity of shapes, which is said to influence emotional valence, as a visual stimulus and aims to confirm the cross-modal effect induced by its sensation. First, based on previous research, the hypotheses about the effects of the complexity of shapes on taste were made. Second, by using particle swarm optimization algorithm, closed curve shapes were generated based on curvature entropy, a quantitative index of the complexity of shapes, which indicates the randomness of curvature transition. Third, cup holders, which had these closed curve shapes on their sides, were created by using a 3D printer. Finally, by comparing the tastes of orange juice in these cup holders, the effect of the complexity of shapes on the perception of sweetness, sourness and intensity was confirmed. The results suggest that the complexity of shapes controlled by curvature entropy weakens the perception of sweetness whereas it enhances that of sourness and intensity. This finding can be used for reducing sugar intake in bottle packaging

Novelty index for curved surface using KL divergence and its effectiveness on industrial products

It is said that the relationship between “novelty” and hedonic response is expressed as an inverse U-shape. The latest studies about perception emphasize “novelty” as a factor of emotion and quantify “novelty” by assessing the difference in amount of information using Kullback-Leibler (KL) divergence. In this study, we proposed a novelty index of closed surfaces using KL divergence focusing on their curvatures. To calculate novelty index, we firstly calculated Gaussian curvature of each vertex in the shape. Then, we defined occurrence probability distribution which represents probability that a vertex has a certain curvature. The KL divergence expresses the difference between the occurrence probability distributions of the standard shape and the target shape. To confirm the effectiveness of the proposed index, we conducted the cognitive experiment using the shape samples of an automobile generated by particle swarm optimization method. The coefficient of determination between the proposed index and sensory evaluation values of “difference” were very high which support the applicability of the index. Furthermore, the consideration of location information increased the correlation with sensory evaluation. This suggests the possibility to evaluate an industrial design requirement quantitatively and contributes to develop the automatic shape generation in product design

Poly(olefin sulfone)s

In this chapter, we introduce poly(olefin sulfone)s and review the recent progress on the photoinduced depolymerization of poly(olefin sulfone)s as well as their applications. Poly(olefin sulfone)s combined with photobase generators (PBGs) are depolymerized upon irradiation with light. A poly(olefin sulfone) is a 1:1 alternating copolymer of olefin monomer and sulfur dioxide in which the protons on the carbons adjacent to the sulfonyl groups can be readily abstracted by a base. This removal leads to a depolymerization chain reaction, resulting in incorporation of a photobase generating chromophore that can undergo a photoinduced unzipping reaction. During this reaction, the original olefin monomer and sulfur dioxide are regenerated from the primary chain of the poly(olefin sulfone). The photoinduced depolymerization of poly(olefin sulfone)s has been investigated for a wide variety of applications, including stereolithography, printable microcircuit fabrication, and removable adhesives

Interference and feature specificity in visual perceptual learning

AbstractPerceptual learning (PL) often shows specificity to a trained feature. We investigated whether feature specificity is related to disruption in PL using the texture discrimination task (TDT), which shows learning specificity to background element but not to target element. Learning was disrupted when orientations of background elements were changed in two successive training sessions (interference) but not in a random order from trial to trial (roving). The presentation of target elements seemed to have reversed effect; learning occurred in two-parts training but not with roving. These results suggest that interference in TDT is feature specific while disruption by roving is not

Photorefractive effect in composites of ferroelectric liquid crystal and photoconductive polymer

The photorefractive effect in composites of a ferroelectric liquid crystal (FLC) and several photoconductive polymers was investigated. The photorefractivity of mixtures of photoconductive polymers and an FLC (polymer/FLC), as well as that of photoconductivepolymer-stabilized ferroelectric liquid crystals (PPS-FLCs) was examined. The polymer/FLC samples exhibited two-beam coupling gain coefficients of about 6,12 cm 21 in a 5 mm gap cell. The photopolymerization of a methacrylate monomer in the FLC medium established a polymer-stabilized state in which the alignment of FLC molecules was mechanically stabilized. The noise in a two-beam coupling signal was reduced significantly in the PPS-FLC samples

The Photorefractive Effect in Liquid Crystals

This chapter summarizes the state of the art of research regarding photorefractive liquid crystals. Photorefractive effect is of interest because it can be used to obtain dynamic holograms, based on interference between dual laser beams within a liquid crystal to generate a refractive index grating. This technique can be employed in numerous diffraction optics applications, such as optical amplifiers, phase-conjugate wave generators, 3D displays, novelty filters, and optical tomography. The photorefractive effect in liquid crystals is especially pronounced, and both ferroelectric and nematic liquid crystals have been researched for this purpose, with the former showing special promise in practical applications. As an example, ferroelectric liquid crystals have been found to readily produce a refractive index grating in conjunction with a significant gain and a formation time of 900 ms

Supersymmetric extension of the sine-Gordon theory with integrable boundary interactions

Integrability and supersymmetry of the supersymmetric extension of the sine-Gordon theory on a half-line are examined and the boundary potential which preserves both the integrability and supersymmetry on the bulk is derived. It appears that unlike the boundary bosonic sine-Gordon theory, integrability and supersymmetry strongly restrict the form and parameters of the boundary potential, so that no free parameter in the boundary term is allowed up to a choice of signs.Comment: Latex 9 pages, submitted to Phys. Lett.