分类: 生物学 >> 生物物理学 提交时间: 2016-05-11
摘要: Luminance and contrast are two major attributes of objects in the visual scene. Luminance and contrast information received by visual neurons are often updated simultaneously. We examined the temporal response properties of neurons in the primary visual cortex (V1) to stimuli whose luminance and contrast were simultaneously changed by 50 Hz. We found that response tuning to luminance changes precedes tuning to contrast changes in V1. For most V1 neurons, the onset time of response tuning to luminance changes was shorter than that to contrast changes. Most neurons carried luminance information in the early response stage, while all neurons carried both contrast and luminance information in the late response stage. The early luminance response suggests that cortical processing for luminance is not as slow as previously thought.
分类: 化学 >> 物理化学 提交时间: 2017-11-05 合作期刊: 《结构化学》
摘要: In this work, the photovoltaic properties of BFBPD-PC61BM system as a promising high-performance organic solar cell (OSC) were theoretically investigated by means of quantum chemistry and molecular dynamics calculations coupled with the incoherent charge-hopping model. Moreover, the hole carrier mobility of BFBPD thin-film was also estimated with the aid of an amorphous cell including 100 BFBPD molecules. Results revealed that the BFBPD-PC61BM system possesses a middle-sized open-circuit voltage of 0.70 V, large short-circuit current density of 17.26 mA·cm-2, high fill factor of 0.846, and power conversion efficiency of 10%. With the Marcus model, in the BFBPD-PC61BM interface, the exciton-dissociation rate, kdis, was predicted to be 2.684×1013 s-1, which is as 3~5 orders of magnitude large as the decay (radiative and non-radiative) one (108~1010 s-1), indicating a high exciton-dissociation efficiency of 100% in the BFBPD-PC61BM interface. Furthermore, by the molecular dynamics simulation, the hole mobility of BFBPD thin-film was predicted to be as high as 1.265×10-2 cm2·V-1·s-1, which can be attributed to its dense packing in solid state.