There is a growing interest in including light source spectrum in advanced lighting software tools and simulations. Given that traditional lighting software tools have been used primarily for calculating photometric quantities, their simplifying assumptions may not be suitable for calculating other α-opic quantities. Commonly used simulation tools use three values to represent the three primary colors (red, green, and blue), but others have expanded the number of bands (i.e., the spectral resolution) to 9, 27, or 81 in an attempt to more accurately represent variations in light source spectrum and downstream spectrally-derived quantities. It remains unclear, however, to what extent spectral resolution affects calculated quantities. To address this gap, a numerical analysis was completed using a large spectral power distribution database (n = 1,302 light sources). Calculated illuminance, α-opic irradiance, luminous efficacy of radiation (LER), melanopic efficacy of radiation (MER), and melanopic to photopic (M/P) ratio were compared for spectral resolutions of 3 and 9 bands compared to a baseline of 81 bands. Across all examined lighting quantities, considerable errors—a mean absolute percent error of 19%— were found when using 3 band calculations. These were reduced to 4% for 9 band calculations. The errors varied by metric and light source type. The results suggest that the use of 9 bands can more accurately characterize performance of different light source types across a range of metrics compared to using 3 bands.
To evaluate the long-term survival and factors that influence survival among a cohort of elderly trauma patients compared with an uninjured cohort.
Design:
A retrospective cohort analysis.
Data Sources:
Health Care Finance Administration, Baltimore, Md, Medicare data.
Subjects:
A cohort of elderly patients (n=9424) hospitalized for injury in 1987 was identified using Medicare hospital discharge abstract data. An uninjured comparison group (n=37 787) was identified from Medicare eligibility files. For injured patients, an Injury Severity Score was generated from theInternational Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9CM)codes. For both cohorts, preexisting illness was assessed byICD-9CMcodes from Health Care Finance Administration outpatient and inpatient data files for 1986 and 1987.
Main Outcome Measures:
Relative risk for mortality within 5 years subsequent to injury, adjusted for age, sex, and preexisting illness, using Cox proportional hazard regression.
Results:
The injured cohort had a significantly reduced 5-year survival when compared with the uninjured group (relative risk [RR] = 1.71; 95% confidence interval, 1.66-1.77). The lower survival persisted even among patients who survived at least 3 years after injury. Coexisting disease, age, and Injury Severity Score were strong predictors of survival.
Conclusions:
The adverse effect of trauma on survival in elderly patients is not isolated to the immediate postinjury period, but lasts years after the trauma episode. Further study is required to identify the reasons for this persistent effect of trauma on subsequent survival. Arch Surg. 1997;132:1010-1014.
For this report, PNNL / the U.S. Department of Energy (DOE) studied a series of past exterior lighting projects at Princeton, in order to document Princeton’s experiences with solid-state lighting (SSL) and the lessons learned along the way, and to show how their approach to SSL projects evolved as their own learning expanded and as the products available improved in performance and sophistication.
Public policy questions such as public funding for Catholic schools, the extent of government involvement in private education, and church-state relations in general are not unique to the United States. This article discusses Catholic education in Scotland, which a view to explaining the ongoing need for cooperation and goodwill in church-state relations concerning schools.
The GATEWAY program evaluated a tunable LED lighting system installed in the new Swedish Medical Behavioral Health Unit in Seattle that incorporates color-tunable luminaires in common areas, and uses advanced controls for dimming and color tuning, with the goal of providing a better environment for staff and patients. The report reviews the design of the tunable lighting system, summarizes two sets of measurements, and discusses the circadian, energy, and commissioning implications as well as lessons learned from the project.
This study explores whether "future" lighting systems that provide greater control and opportunity for circadian synchronization are acceptable to participants in the role of patients.Tunable, dimmable light emitting diode systems provide multiple potential benefits for healthcare. They can provide significant energy savings, support circadian synchronization by varying the spectrum and intensity of light over the course of the day, address nighttime navigation needs, and provide user-friendly control. There is an emerging understanding of the important visual and nonvisual effects of light; however, important questions remain about the experience and acceptability of this "future" lighting if we are to adopt it broadly.Volunteer participants (34) performed a series of tasks typical of patients, such as reading or watching a video, in a full-scale simulated inpatient room. Each participant conducted these tasks under 12 lighting conditions in a counterbalanced order that included varying illuminance levels, correlated color temperatures (CCTs), and in a few conditions, saturated colors. The participants rated each lighting condition on comfort, intensity, appropriateness, and naturalness.The participants found that conditions with CCTs of 5,000 K and higher were significantly less comfortable and less natural than conditions with lower CCTs. Conditions with lighting distributed in multiple zones in the patient room were viewed more favorably than a traditional overbed configuration. The participants in this simulated patient study reacted negatively to colored lighting on the footwall of the room but found a mixture of warmer and cooler luminaire CCTs acceptable.
This report focuses on four exterior solid-state lighting projects that have been completed at Princeton since 2008, when the University adopted a comprehensive sustainability plan. Through these initial projects – which include a parking garage, a pedestrian path, and two parking lot installations – the school’s facilities engineering staff learned important lessons about SSL technology and gained experience in dealing with the rapidly changing landscape of lighting manufacturers and their suppliers.
