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Brady, A., Willis, B., Harder, L., & Vizel, P. (2016). Lunar Phase Modulates Circadian Gene Expression Cycles in the Broadcast Spawning Coral Acropora millepora. Biol Bullet, 230(2), 130–142.
Abstract: Many broadcast spawning corals in multiple reef regions release their gametes with incredible temporal precision just once per year, using the lunar cycle to set the night of spawning. Moonlight, rather than tides or other lunar-regulated processes, is thought to be the proximate factor responsible for linking the night of spawning to the phase of the Moon. We compared patterns of gene expression among colonies of the broadcast spawning coral Acropora millepora at different phases of the lunar cycle, and when they were maintained under one of three experimentally simulated lunar lighting treatments: i) lunar lighting conditions matching those on the reef, or lunar patterns mimicking either ii) constant full Moon conditions, or iii) constant new Moon conditions. Normal lunar illumination was found to shift both the level and timing of clock gene transcription cycles between new and full moons, with the peak hour of expression for a number of genes occurring earlier in the evening under a new Moon when compared to a full Moon. When the normal lunar cycle is replaced with nighttime patterns equivalent to either a full Moon or a new Moon every evening, the normal monthlong changes in the level of expression are destroyed for most genes. In combination, these results indicate that daily changes in moonlight that occur over the lunar cycle are essential for maintaining normal lunar periodicity of clock gene transcription, and this may play a role in regulating spawn timing. These data also show that low levels of light pollution may have an impact on coral biological clocks.
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Ayaki, M., Hattori, A., Maruyama, Y., Nakano, M., Yoshimura, M., Kitazawa, M., et al. (2016). Protective effect of blue-light shield eyewear for adults against light pollution from self-luminous devices used at night. Chronobiol Int, 33(1), 134–139.
Abstract: We investigated sleep quality and melatonin in 12 adults who wore blue-light shield or control eyewear 2 hours before sleep while using a self-luminous portable device, and assessed visual quality for the two eyewear types. Overnight melatonin secretion was significantly higher after using the blue-light shield (P < 0.05) than with the control eyewear. Sleep efficacy and sleep latency were significantly superior for wearers of the blue-light shield (P < 0.05 for both), and this group reported greater sleepiness during portable device use compared to those using the control eyewear. Participants rated the blue-light shield as providing acceptable visual quality.
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Zhao, X., Shi, H., Yu, H., & Yang, P. (2016). Inversion of Nighttime PM2.5 Mass Concentration in Beijing Based on the VIIRS Day-Night Band. Atmosphere, 7(10), 136.
Abstract: In order to monitor nighttime particular matter (PM) air quality in urban area, a back propagation neural network (BP neural network) inversion model is established, using low-light radiation data from the day/night band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (S-NPP) satellite. The study focuses on the moonless and cloudless nights in Beijing during March–May 2015. A test is carried out by selecting surface PM2.5 data from 12 PM2.5 automatic monitoring stations and the corresponding night city light intensity from DNB. As indicated by the results, the linear correlation coefficient (R) between the results and the corresponding measured surface PM2.5 concentration is 0.91, and the root-mean-square error (RMSE) is 14.02 μg/m3 with the average of 59.39 μg/m3. Furthermore, the BP neural network model shows better accuracy when air relative humility ranges from 40% to 80% and surface PM2.5 concentration exceeds 40 μg/m3. The study provides a superiority approach for monitoring PM2.5 air quality from space with visible light remote sensing data at night.
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Tähkämö, L., Räsänen, R. - S., & Halonen, L. (2016). Life cycle cost comparison of high-pressure sodium and light-emitting diode luminaires in street lighting. Int J Life Cycle Assess, 21(2), 137–145.
Abstract: Purpose
Cities and municipalities are facing a great challenge in 2015 when the widely used high-pressure mercury lamps are banned from the European Union market. This results to approximately 18 million lamps to be changed to other light source technologies suitable for outdoor lighting. The most probable replacement technologies are high-pressure sodium and light-emitting diode luminaires. The article provides economic information for the cities and municipalities to use when making the decision on the choice of technology.
Methods
A life cycle cost analysis was conducted for the high-pressure sodium and light-emitting diode luminaires including the investment costs, operating costs and residual value over 30-year time frame. The investment costs included the purchase prices of all parts, freight and installation costs. The operating costs accounted for the energy and maintenance costs, and the residual value was calculated using the 25 % estimate of the initial purchase price. The approach of the calculation considered only the luminaires to be installed; the scope of the study excluded the previous installations, which may contain any light source technology or be inexistent. The analysis excluded the poles, wiring and other infrastructure. A sensitivity analysis additionally studied six scenarios, in which relevant calculation parameters were changed.
Results and discussion
The life cycle cost analysis of the two road lighting luminaire technologies showed that the HPS luminaire was normally a more economical solution compared to the light-emitting diode (LED) luminaire. The total life cycle costs of the HPS luminaire were 45 % lower than those of the LED luminaire per kilometre. However, the scenarios in the sensitivity analysis indicated that there were circumstances where the cost-efficiency of the LED luminaire was particularly improved. In order for the LED technology to become fully competitive against the HPS technology, several scenarios have to take place simultaneously. The life cycle costs of the LED luminaire were reduced compared to the HPS luminaire by increased electricity price, exclusion of spot replacements, reduced purchase price and modularity of the LED luminaire.
Conclusions
Despite the greater luminous efficacy, the LED luminaire was found to have greater life cycle costs compared to the HPS luminaire. However, the LED technology is expected to become more economical in the future due to the development in luminous efficacy, improved product quality, reduction in the purchase price and the enhanced competition in the LED segment. Despite the unfavourable cost structure, the LED technology offers other benefits, such as lighting controls and colour characteristics.
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Lee, S., & Cao, C. (2016). Soumi NPP VIIRS Day/Night Band Stray Light Characterization and Correction Using Calibration View Data. Remote Sensing, 8(2), 138.
Abstract: The Soumi NPP VIIRS Day/Night Band (DNB) nighttime imagery quality is affected by stray light contamination. In this study, we examined the relationship between the Earth scene stray light and the signals in VIIRS’s calibrators to better understand stray light characteristics and to improve upon the current correction method. Our analyses showed the calibrator signal to be highly predictive of Earth scene stray light and can provide additional stray light characteristics that are difficult to obtain from Earth scene data alone. In the current stray light correction regions (mid-to-high latitude), the stray light onset angles can be tracked by calibration view data to reduce correction biases. In the southern hemisphere, it is possible to identify the angular extent of the additional stray light feature in the calibration view data and develop a revised correction method to remove the additional stray light occurring during the southern hemisphere springtime. Outside of current stray light correction region, the analysis of calibration view data indicated occasional stray light contamination at low latitude and possible background biases caused by Moon illumination. As stray light affects a significant portion of nighttime scenes, further refinement in characterization and correction is important to ensure VIIRS DNB imagery quality for Soumi NPP and future missions.
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