|Home||<< 1 2 3 4 5 6 7 8 9 10 >> [11–20]|
Fuller, G. (Ed.). (2013). The Night Shift: Lighting and Nocturnal Strepsirrhine Care in Zoos. Ph.D. thesis, , .
Abstract: Over billions of years of evolution, light from the sun, moon, and stars has provided
organisms with reliable information about the passage of time. Photic cues entrain
the circadian system, allowing animals to perform behaviors critical for survival and
reproduction at optimal times. Modern artificial lighting has drastically altered
environmental light cues. Evidence is accumulating that exposure to light at night
(particularly blue wavelengths) from computer screens, urban light pollution, or as
an occupational hazard of night-shift work has major implications for human health.
Nocturnal animals are the shift workers of zoos; they are generally housed on
reversed light cycles so that daytime visitors can observe their active behaviors. As a
result, they are exposed to artificial light throughout their subjective night. The goal
of this investigation was to examine critically the care of nocturnal strepsirrhine
primates in North American zoos, focusing on lorises (Loris and Nycticebus spp.) and pottos (Perodicticus potto). The general hypothesis was that exhibit lighting design affects activity patterns and circadian physiology in nocturnal strepsirrhines. The
first specific aim was to assess the status of these populations. A multi-institutional husbandry survey revealed little consensus among zoos in lighting design, with both red and blue light commonly used for nocturnal illumination. A review of medical records also revealed high rates of neonate mortality. The second aim was to
develop methods for measuring the effects of exhibit lighting on behavior and
health. The use of actigraphy for automated activity monitoring was explored.
Methods were also developed for measuring salivary melatonin and cortisol as
indicators of circadian disruption. Finally, a multi-institutional study was conducted
comparing behavioral and endocrine responses to red and blue dark phase lighting.
These results showed greater activity levels in strepsirrhines housed under red light than blue. Salivary melatonin concentrations in pottos suggested that blue light
suppressed nocturnal melatonin production at higher intensities, but evidence for
circadian disruption was equivocal. These results add to the growing body of
evidence on the detrimental effects of blue light at night and are a step towards
empirical recommendations for nocturnal lighting design in zoos.
Gil-de-Castro, A., Moreno-Munoz, A., Larsson, A., de la Rosa, J., & Bollen, M. (2013). LED street lighting: A power quality comparison among street light technologies. Lighting Research and Technology, 45(6), 710–728.
Abstract: High-pressure sodium lamps are currently the main lamps used in public lighting. However, the possibility of using high-power light emitting diode (LEDs) for street lighting is growing continuously due to their greater energy efficiency, robustness, long life and light control. The aim of this paper is to study the power quality of high-power lighting networks based on LED and high-pressure sodium lamps. Both electromagnetic and dimmable electronic ballasts, which can dim the lamp output smoothly and uniformly, have been used connected to high-pressure sodium lamps. High-pressure sodium lamps connected to electronic equipment have been tested with different arc power levels using dimming on a 230 V power supply. The study presented in this paper is completely based on measurements, including harmonic currents in the frequency range up to 150 kHz for all the technologies. The main results show a broadband spectrum in LED lamps which confirms other research in ﬂuorescent lamps powered by high-frequency ballasts. Results also indicate a decrease in the harmonic value with increasing harmonic order, and a decrease in the harmonic value at half load (60%) compared with full load (100%). Although total harmonic distortion of the current is lower with high-pressure sodium lamps connected to electronic rather than electromagnetic ballasts, LED lamps achieved the lowest total harmonic distortion of current.
Sweater-Hickcox, K., Narendran, N., Bullough, J., & Freyssinier, J. (2013). Effect of different coloured luminous surrounds on LED discomfort glare perception. Lighting Research and Technology, 45(4), 464–475.
Abstract: Recently, there has been increased interest in energy-efficient lighting as energy resources become higher in demand. Anecdotal evidence suggests that certain populations believe light-emitting diodes (LED) produce more glare than traditional technologies. This may be due to a number of factors such as spectral power distribution (SPD), source luminance, or beam intensity distribution. A study was conducted to assess the effect of different SPDs on the perception of discomfort glare from an LED source. For the range of conditions evaluated, the presence of any luminous surround significantly reduced the perception of discomfort glare from the LED array. The blue luminous surround reduced discomfort glare perception significantly less than the white or the yellow luminous surrounds. The implications for solid-state lighting systems are discussed.
Kostic, A., Kremic, M., Djokic, L., & Kostic, M. (2013). Light-emitting diodes in street and roadway lighting – a case study involving mesopic effects. Lighting Research and Technology, 45(2), 217–229.
Abstract: The paper considers the justification for the application of light-emitting diode (LED) technology to urban lighting. The results suggest that LEDs are convenient for architectural lighting and deserve to be considered for use in ambient lighting. The recently developed Commission Internationale de lâEclairage (CIE) mesopic system enabled the inclusion of mesopic effects into a comprehensive techno-economic analysis, which dealt with efficiency, maintenance and financial aspects of the use of LEDs in street and roadway lighting. It is concluded that the average energy savings when using LED instead of high-pressure sodium (HPS) luminaires amount to 19â26% for single-sided, staggered and opposite layouts, although they are frequently negligible if mesopic effects are not included. The total costs of the LED lighting solutions, even including mesopic effects, are 1.36 to 6.44 times higher than those of the comparable HPS lighting solutions. Therefore, LEDs are questionable for street and roadway lighting.
Kayaba, M., Iwayama, K., Ogata, H., Seya, Y., Tokuyama, K., & Satoh, M. (2013). Drowsiness and low energy metabolism in the following morning induced by nocturnal blue light exposure. Sleep Medicine, 14, e166–e167.
Evening light exposure debilitates the circadian rhythm and elicits sleep disturbance. Blue light peak wavelengths, around 460 nm, suppress melatonin secretion via the non-image-forming system. The effects of nocturnal blue light exposure on sleep have been reported to be specific but rather small (MÃ¼nch, 2008). This study was designed to assess the effect of nocturnal blue light exposure on sleep and energy metabolism until noon the next day.
Materials and methods
Nine healthy male volunteers aged between 21 and 25 participated in this study which had a balanced cross-over design with intrasubject comparisons. After 2 h dark adaptation, the subjects were exposed to blue light or no light for 2 h. The peak wavelength of the blue LED was 465 nm, and the horizontal irradiance of the blue light at the height of eye was at 7.02fÃW/cm2. Sleep was recorded polysomnographically, and energy metabolism was measured with a whole body indirect calorimeter.
There were no significant differences in sleep architecture and energy metabolism during the night. However, dozing (stages 1 and 2) was significantly higher (26.0 < 29.4 vs 6.3 < 8.1 min, P < 0.05), and energy expenditure, O2 consumption, CO2 production and the thermic effect of food (increase in energy expenditure after breakfast) were significantly lower the following morning in the blue light exposure subjects.
Contrary to our expectation, sleep architecture and energy metabolism during sleep were not affected by evening exposure to blue light. It might be due to our milder intervention by which subjects in a sitting position did not gaze at the light source set on the ceiling, while the subjects in previous studies directly received brighter light via custom built goggles (Cajochen, 2005; MÃ¼nch, 2008) or gazed at a light source under the influence of mydriatic agents to dilate pupils (Brainard, 2001). New findings of the present study were that dozing (stages 1 and 2) was significantly increased, and energy metabolism was significantly lower the following morning in blue light exposed subjects. This suggests that modulation of the circadian rhythm is affected by nocturnal blue light exposure and the effect continues in the following daytime even if the intervention was mild.