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Author West, K.E.; Jablonski, M.R.; Warfield, B.; Cecil, K.S.; James, M.; Ayers, M.A.; Maida, J.; Bowen, C.; Sliney, D.H.; Rollag, M.D.; Hanifin, J.P.; Brainard, G.C.
Title (up) Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans Type Journal Article
Year 2011 Publication Journal of Applied Physiology (Bethesda, Md. : 1985) Abbreviated Journal J Appl Physiol (1985)
Volume 110 Issue 3 Pages 619-626
Keywords Circadian Rhythm/*physiology/*radiation effects; Color; Dose-Response Relationship, Radiation; Humans; Lighting/*methods; Melatonin/*blood; Metabolic Clearance Rate/radiation effects; Photic Stimulation/*methods; Radiation Dosage; Retina/*physiology/*radiation effects; Semiconductors; Young Adult; blue light
Abstract Light suppresses melatonin in humans, with the strongest response occurring in the short-wavelength portion of the spectrum between 446 and 477 nm that appears blue. Blue monochromatic light has also been shown to be more effective than longer-wavelength light for enhancing alertness. Disturbed circadian rhythms and sleep loss have been described as risk factors for astronauts and NASA ground control workers, as well as civilians. Such disturbances can result in impaired alertness and diminished performance. Prior to exposing subjects to short-wavelength light from light-emitting diodes (LEDs) (peak lambda = 469 nm; 1/2 peak bandwidth = 26 nm), the ocular safety exposure to the blue LED light was confirmed by an independent hazard analysis using the American Conference of Governmental Industrial Hygienists exposure limits. Subsequently, a fluence-response curve was developed for plasma melatonin suppression in healthy subjects (n = 8; mean age of 23.9 +/- 0.5 years) exposed to a range of irradiances of blue LED light. Subjects with freely reactive pupils were exposed to light between 2:00 and 3:30 AM. Blood samples were collected before and after light exposures and quantified for melatonin. The results demonstrate that increasing irradiances of narrowband blue-appearing light can elicit increasing plasma melatonin suppression in healthy subjects (P < 0.0001). The data were fit to a sigmoidal fluence-response curve (R(2) = 0.99; ED(50) = 14.19 muW/cm(2)). A comparison of mean melatonin suppression with 40 muW/cm(2) from 4,000 K broadband white fluorescent light, currently used in most general lighting fixtures, suggests that narrow bandwidth blue LED light may be stronger than 4,000 K white fluorescent light for suppressing melatonin.
Address Dept. of Neurology, Thomas Jefferson Univ., Philadelphia, Pennsylvania 19107, USA
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0161-7567 ISBN Medium
Area Expedition Conference
Notes PMID:21164152 Approved no
Call Number IDA @ john @ Serial 287
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Author Vetter, C.; Juda, M.; Lang, D.; Wojtysiak, A.; Roenneberg, T.
Title (up) Blue-enriched office light competes with natural light as a zeitgeber Type Journal Article
Year 2011 Publication Scandinavian Journal of Work, Environment & Health Abbreviated Journal Scand J Work Environ Health
Volume 37 Issue 5 Pages 437-445
Keywords *Circadian Rhythm; *Color; Humans; *Lighting; *Occupational Health; Sleep; Wakefulness; blue light; circadian disruption; Circadian rhythm; sleep
Abstract OBJECTIVES: Circadian regulation of human physiology and behavior (eg, body temperature or sleep-timing), depends on the “zeitgeber” light that synchronizes them to the 24-hour day. This study investigated the effect of changing light temperature at the workplace from 4000 Kelvin (K) to 8000 K on sleep-wake and activity-rest behavior. METHODS: An experimental group (N=27) that experienced the light change was compared with a non-intervention group (N=27) that remained in the 4000 K environment throughout the 5-week study period (14 January to 17 February). Sleep logs and actimetry continuously assessed sleep-wake behavior and activity patterns. RESULTS: Over the study period, the timing of sleep and activity on free days steadily advanced parallel to the seasonal progression of sunrise in the non-intervention group. In contrast, the temporal pattern of sleep and activity in the experimental group remained associated with the constant onset of work. CONCLUSION: The results suggest that artificial blue-enriched light competes with natural light as a zeitgeber. While subjects working under the warmer light (4000 K) appear to entrain (or synchronize) to natural dawn, the subjects who were exposed to blue-enriched (8000 K) light appear to entrain to office hours. The results confirm that light is the dominant zeitgeber for the human clock and that its efficacy depends on spectral composition. The results also indicate that blue-enriched artificial light is a potent zeitgeber that has to be used with diligence.
Address Institute for Medical Psychology, Centre of Chronobiology, Ludwig-Maximilians-Universitat, Munich, Germany
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0355-3140 ISBN Medium
Area Expedition Conference
Notes PMID:21246176 Approved no
Call Number IDA @ john @ Serial 350
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Author Marimuthu C.; Kirubakaran V.
Title (up) Carbon and Energy Pay Back Period for the Solar Street Light using Life Cycle Assessment Type Journal Article
Year 2015 Publication International Journal of ChemTech Research Abbreviated Journal
Volume 8 Issue 3 Pages 1125-1130
Keywords Lighting; Economics
Abstract Electronic street lights are big consumers of energy, costing millions to cities and municipalities around the world. Solar Street light is one of the method to reduce the power consumption by generate the energy using the solar Photovoltaic panel. This system includes the power generators (panel), storage (batteries) and management (controller) as well as the light, poles and weather proof housing for batteries. Life cycle inventories are based on manufacturers data combined with additional calculation and assumption. The Life Cycle Assessment (LCA) methodology used in this research was based on the ISO 14040 and 14044 series. In this paper, the LCA method is used to investigate the environmental impacts of two types of street light technology, conventional street light and solar street light. The cradle to grave analysis for conventional and solar street light includes raw material extraction, production, uses and end of life scenario. The detail investigation has made for the existing solar street light present at Gandhigram Rural University, Dindigul Dist, Tamil Nadu. The specification of the solar street light is 80W capacity, 1.2 m2 area of panel and 135Ah – 12V battery. The total no of poles is 70. For the above system carbon intensity, Energy Pay Back Period and Carbon Pay Back Period have been calculated and compared with conventional street light. The result from the study will support local decision makers when seeking a balance between the environmental, financial and social requirements of public lighting services.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0974-4290 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number UP @ altintas1 @ Serial 3147
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Author Zielinska-Dabkowska, K.
Title (up) Case study of “Walk”: a video installation integrated into the facade of a store in Zurich/CH Type Journal Article
Year 2016 Publication Professional Lighting Design Abbreviated Journal Prof Lighting Des
Volume Issue 101 Pages 52-58
Keywords Lighting; planning; commentary
Abstract With the rapid development of solid state lighting technology and the availability of LED light sources, coupled with the benefits they offer such as energy efficiency, long lifespan and the fact that they can be controlled and programmed, we are now finding LEDs being more widely used for animated advertising. In spite of the pace at which SSL is developing, or perhaps because of this, there is a distinct lack of evaluation guidelines or recommendations for professional designers. It is therefore essential that more research is carried out on this issue on an international scale, and that experts in the field get their heads together in order to formulate some basic guidelines that can be applied in practice.
Address Faculty of Architecture & Design, Hochschule Wismar, Wismar, Germany; k.zielinska-dabkowska(at)hs-wismar.de
Corporate Author Thesis
Publisher Verlag Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 1479
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Author Pagden, M.; Ngahane, K.; Amin, M.S.R.
Title (up) Changing the colour of night on urban streets – LED vs. part-night lighting system Type Journal Article
Year 2019 Publication Socio-Economic Planning Sciences Abbreviated Journal Socio-Economic Planning Sciences
Volume in press Issue Pages 100692
Keywords Energy; Planning; Economics; United Kingdom; LED; Lighting
Abstract Many cities in the United Kingdom are upgrading the streetlights to white light-emitting diode (LED) lamps for reducing the electricity costs and attaining the sustainable energy solutions. Installation of LED lamps on urban street requires higher installation costs and a long-term period to payback benefits of replacing outdated streetlights in terms of energy savings and costs. To achieve the short-term energy efficiency of urban street lighting, city councils sometimes adopt the part-night lighting system particularly in the residential areas. The Coventry City Council recently replaced 29,701 existing sodium lights with LED lamps. This paper performs the economic analyses to understand the feasibility of two street lighting systems: LED lamps and ‘part-night’ lightings on the Coventry streets during the twenty-year period assuming the return period of investment is twenty years. The projection of energy consumption and costs for LED lamps and part-night lighting systems shows that electricity can be saved by 44% and 21% comparing to current electricity usages, respectively. Considering the budgetary constraints of Coventry City Council, this paper concludes that the part-night lighting system may be beneficial in short-term period, but it is economically feasible to replace the existing lower efficiency lights with LED lamps.
Address Faculty of Engineering, Environment & Computing, Coventry University, Priory St, Coventry, West Midlands, CV1 5FB, United Kingdom; pagdenm(at)uni.coventry.ac.uk
Corporate Author Thesis
Publisher English Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0038-0121 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number GFZ @ kyba @ Serial 2234
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