The Impact of LED Color Rendering on the Dark Adaptation of Human Eyes at Tunnel Entrances.

The dark adaptation of drivers' eyes at a tunnel entrance seriously affects traffic safety. This can be improved by the design of tunnel lighting. Light-Emitting Diode (LEDs) have been applied as a new type of luminaire in tunnel lighting in recent years, but at present, there are few studies on the influence of color rendering of LEDs on tunnel traffic safety, and there is no explicit indicator for the selection of appropriate color rendering parameters in tunnel lighting specifications, which has aroused researchers' concern. In this article, several new color rendering evaluation indexes were compared, and as a result, it is considered that CRI2012 (a color difference-based color rendering index) is more suitable for evaluating the color rendering of LEDs used at tunnel entrances. The dark adaptation phenomenon was simulated in the laboratory. Four CRI2012s, three color temperatures and eight colored targets were used in the experiments. The results showed that yellow, silver and white can provide shorter reaction times, while red and brown lead to longer reaction times, which can provide a reference for the design of road and warning signs at tunnel entrances. The effect of target color on reaction time was greater than that of color rendering. Under most target colors, the higher the CRI2012, the shorter the reaction time. When designing the color rendering of the LEDs at a tunnel entrance, the value should thus be as large as possible (close to 100), and a lower color temperature value (about 2800 K) should be selected. This paper provides technical support for tunnel lighting design and a reference for tunnel lighting specifications, which is of significance to improve driving safety and avoid traffic accidents in highway tunnels.

Influence of Vehicle Speed on the Characteristics of Driver's Eye Movement at a Highway Tunnel Entrance during Day and Night Conditions: A Pilot Study.

The aim of this study was to investigate how vehicle speed influences the characteristics of driver's eye movement at highway tunnel entrances during day and night. In this study, six drivers' eye movement data (from 200 m before tunnel entrance to 200 m inside tunnel entrance) under five predetermined vehicle speeds (40, 50, 60, 70 and 80 km/h) in the daytime and three predetermined vehicle speeds (40, 60 and 80 km/h) in the nighttime were recorded using the non-intrusive Dikablis Professional eye-tracking system. Pupil size, the average fixation duration time and the average number of fixation were analyzed and then the influence of the vehicle speed on these parameters was evaluated by means of IBM SPSS Statistics 20.0. The results for pupil size in daytime increased when approaching the tunnel entrance, while as for nighttime, pupil size decreased when approaching the tunnel entrance and then increased after entering the tunnel. The pupil size in daytime has a significant negative correlation with vehicle speed, while the pupil size in nighttime did not show a significant association with vehicle speed. Furthermore, the average fixation duration in daytime increased when entering the tunnel, and had a significant negative correlation with vehicle speed. Also, the average number of fixations in daytime decreased when entering the tunnel and has a significant negative correlation with vehicle speed. However, the average fixation duration and the average number of fixations in nighttime did not show any significant association with vehicle speed. Moreover, limitations and future directions of the study are discussed for the further investigation.

Physical exercise before pregnancy helps the development of mouse embryos produced in vitro.

Effects of pre-gestational physical activity on the later development of embryos generated in vitro were evaluated. Kunming mice were divided into two groups, namely exercised and unexercised, with the former undergoing physical training on a motor-driven leveled treadmill over a period of 4weeks (5days/week and 60min/day). After that, following superovulation, collection of oocytes from both groups was performed for in vitro fertilization (IVF) and somatic cell nuclear transfer (SCNT). Notably and specifically, natural mating between the unexercised mice was also done for in vivo fertilization (IVIF). Observation on the preimplantation embryo development showed that SCNT embryos from exercised group (NEM) had significant higher rates of cleavage and formation of blastocyst containing more blastomeres compared to SCNT embryos from unexercised group (NCM); while IVF embryos in exercised group (FEM) showed a significant higher rate of cleavage and blastocyst formation. Further analysis of embryos from the trained group on the molecular level demonstrated a prominent increase in terms of ATP levels, mitochondria membrane potential (Δψm) and mtDNA copy number and an obvious decrease in H2O2 concentration than those from the respective control group. Meanwhile, epigenetically, methylation levels of CpG sites on imprinting control regions of imprinted genes (Igf2, Igf2r, Meg 3 and H19) in the NEM embryos were normalized in exercise groups compared to the NCM embryos, which were comparable to the in vivo-derived embryos. Moreover, global DNA and histone methylation (H3K4m2, H3K9m3 and H3K36m) further confirmed that NEM-derived embryos and in vivo-derived ones stay in the same cluster, indicating that physical activity in pre-pregnancy facilitates the maintenance of epigenetic modifications. Generally, these results strongly suggest that physical exercise before pregnancy is in favor of the later embryo development.