Human Adolescent Phase Response Curves to Bright White Light.

Science.gov (United States)

Crowley, Stephanie J; Eastman, Charmane I

2017-08-01

Older adolescents are particularly vulnerable to circadian misalignment and sleep restriction, primarily due to early school start times. Light can shift the circadian system and could help attenuate circadian misalignment; however, a phase response curve (PRC) to determine the optimal time for receiving light and avoiding light is not available for adolescents. We constructed light PRCs for late pubertal to postpubertal adolescents aged 14 to 17 years. Participants completed 2 counterbalanced 5-day laboratory sessions after 8 or 9 days of scheduled sleep at home. Each session included phase assessments to measure the dim light melatonin onset (DLMO) before and after 3 days of free-running through an ultradian light-dark (wake-sleep) cycle (2 h dim [~20 lux] light, 2 h dark). In one session, intermittent bright white light (~5000 lux; four 20-min exposures) was alternated with 10 min of dim room light once per day for 3 consecutive days. The time of light varied among participants to cover the 24-h day. For each individual, the phase shift to bright light was corrected for the free-run derived from the other laboratory session with no bright light. One PRC showed phase shifts in response to light start time relative to the DLMO and another relative to home sleep. Phase delay shifts occurred around the hours corresponding to home bedtime. Phase advances occurred during the hours surrounding wake time and later in the afternoon. The transition from delays to advances occurred at the midpoint of home sleep. The adolescent PRCs presented here provide a valuable tool to time bright light in adolescents.

Artificial light alters natural regimes of night-time sky brightness

Science.gov (United States)

Davies, Thomas W.; Bennie, Jonathan; Inger, Richard; Gaston, Kevin J.

2013-01-01

Artificial light is globally one of the most widely distributed forms of anthropogenic pollution. However, while both the nature and ecological effects of direct artificial lighting are increasingly well documented, those of artificial sky glow have received little attention. We investigated how city lights alter natural regimes of lunar sky brightness using a novel ten month time series of measurements recorded across a gradient of increasing light pollution. In the city, artificial lights increased sky brightness to levels six times above those recorded in rural locations, nine and twenty kilometers away. Artificial lighting masked natural monthly and seasonal regimes of lunar sky brightness in the city, and increased the number and annual regime of full moon equivalent hours available to organisms during the night. The changes have potentially profound ecological consequences.

Nanopatterned yttrium aluminum garnet phosphor incorporated film for high-brightness GaN-based white light emitting diodes

International Nuclear Information System (INIS)

Cho, Joong-yeon; Park, Sang-Jun; Ahn, Jinho; Lee, Heon

2014-01-01

In this study, we fabricated high-brightness white light emitting diodes (LEDs) by developing a nanopatterned yttrium aluminum garnet (YAG) phosphor-incorporated film. White light can be obtained by mixing blue light from a GaN-based LED and yellow light of the YAG phosphor-incorporated film. If white light sources can be fabricated by exciting proper yellow phosphor using blue light, then these sources can be used instead of the conventional fluorescent lamps with a UV source, for backlighting of displays. In this work, a moth-eye structure was formed on the YAG phosphor-incorporated film by direct spin-on glass (SOG) printing. The moth-eye structures have been investigated to improve light transmittance in various optoelectronic devices, including photovoltaic solar cells, light emitting diodes, and displays, because of their anti-reflection property. Direct SOG printing, which is a simple, easy, and relatively inexpensive process, can be used to fabricate nanoscale structures. After direct SOG printing, the moth-eye structure with a diameter of 220 nm was formed uniformly on the YAG phosphor-incorporated film. As a result of moth-eye patterning on the YAG phosphor-incorporated film, the light output power of a white LED with a patterned YAG phosphor-incorporated film increased to up to 13% higher than that of a white LED with a non-patterned film. - Highlights: • GaN-based high-brightness white LED was prepared using patterned YAG phosphor-incorporated films. • Direct hydrogen silsesquioxane printing was used to form moth-eye patterns on the YAG films. • The electroluminescence intensity of the white LED was enhanced by up to 14.9%

Nanopatterned yttrium aluminum garnet phosphor incorporated film for high-brightness GaN-based white light emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Cho, Joong-yeon; Park, Sang-Jun [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Ahn, Jinho, E-mail: jhahn@hanyang.ac.kr [Department of Material Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lee, Heon, E-mail: heonlee@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

2014-11-03

In this study, we fabricated high-brightness white light emitting diodes (LEDs) by developing a nanopatterned yttrium aluminum garnet (YAG) phosphor-incorporated film. White light can be obtained by mixing blue light from a GaN-based LED and yellow light of the YAG phosphor-incorporated film. If white light sources can be fabricated by exciting proper yellow phosphor using blue light, then these sources can be used instead of the conventional fluorescent lamps with a UV source, for backlighting of displays. In this work, a moth-eye structure was formed on the YAG phosphor-incorporated film by direct spin-on glass (SOG) printing. The moth-eye structures have been investigated to improve light transmittance in various optoelectronic devices, including photovoltaic solar cells, light emitting diodes, and displays, because of their anti-reflection property. Direct SOG printing, which is a simple, easy, and relatively inexpensive process, can be used to fabricate nanoscale structures. After direct SOG printing, the moth-eye structure with a diameter of 220 nm was formed uniformly on the YAG phosphor-incorporated film. As a result of moth-eye patterning on the YAG phosphor-incorporated film, the light output power of a white LED with a patterned YAG phosphor-incorporated film increased to up to 13% higher than that of a white LED with a non-patterned film. - Highlights: • GaN-based high-brightness white LED was prepared using patterned YAG phosphor-incorporated films. • Direct hydrogen silsesquioxane printing was used to form moth-eye patterns on the YAG films. • The electroluminescence intensity of the white LED was enhanced by up to 14.9%.

Afternoon nap and bright light exposure improve cognitive flexibility post lunch.

Directory of Open Access Journals (Sweden)

Hichem Slama

Full Text Available Beneficial effects of napping or bright light exposure on cognitive performance have been reported in participants exposed to sleep loss. Nonetheless, few studies investigated the effect of these potential countermeasures against the temporary drop in performance observed in mid-afternoon, and even less so on cognitive flexibility, a crucial component of executive functions. This study investigated the impact of either an afternoon nap or bright light exposure on post-prandial alterations in task switching performance in well-rested participants. Twenty-five healthy adults participated in two randomized experimental conditions, either wake versus nap (n=15, or bright light versus placebo (n=10. Participants were tested on a switching task three times (morning, post-lunch and late afternoon sessions. The interventions occurred prior to the post-lunch session. In the nap/wake condition, participants either stayed awake watching a 30-minute documentary or had the opportunity to take a nap for 30 minutes. In the bright light/placebo condition, participants watched a documentary under either bright blue light or dim orange light (placebo for 30 minutes. The switch cost estimates cognitive flexibility and measures task-switching efficiency. Increased switch cost scores indicate higher difficulties to switch between tasks. In both control conditions (wake or placebo, accuracy switch-cost score increased post lunch. Both interventions (nap or bright light elicited a decrease in accuracy switch-cost score post lunch, which was associated with diminished fatigue and decreased variability in vigilance. Additionally, there was a trend for a post-lunch benefit of bright light with a decreased latency switch-cost score. In the nap group, improvements in accuracy switch-cost score were associated with more NREM sleep stage N1. Thus, exposure to bright light during the post-lunch dip, a countermeasure easily applicable in daily life, results in similar

Bright green light treatment of depression for older adults [ISRCTN69400161

Directory of Open Access Journals (Sweden)

Knickerbocker Nancy C

2005-11-01

Full Text Available Abstract Background Bright white light has been successfully used for the treatment of depression. There is interest in identifying which spectral colors of light are the most efficient in the treatment of depression. It is theorized that green light could decrease the intensity duration of exposure needed. Late Wake Treatment (LWT, sleep deprivation for the last half of one night, is associated with rapid mood improvement which has been sustained by light treatment. Because spectral responsiveness may differ by age, we examined whether green light would provide efficient antidepressant treatment in an elder age group. Methods We contrasted one hour of bright green light (1,200 Lux and one hour of dim red light placebo ( Results The protocol was completed by 33 subjects who were 59 to 80 years old. Mood improved on average 23% for all subjects, but there were no significant statistical differences between treatment and placebo groups. There were negligible adverse reactions to the bright green light, which was well tolerated. Conclusion Bright green light was not shown to have an antidepressant effect in the age group of this study, but a larger trial with brighter green light might be of value.

High-efficient and brightness white organic light-emitting diodes operated at low bias voltage

Science.gov (United States)

Zhang, Lei; Yu, Junsheng; Yuan, Kai; Jian, Yadong

2010-10-01

White organic light-emitting diodes (OLEDs) used for display application and lighting need to possess high efficiency, high brightness, and low driving voltage. In this work, white OLEDs consisted of ambipolar 9,10-bis 2-naphthyl anthracene (ADN) as a host of blue light-emitting layer (EML) doped with tetrabutyleperlene (TBPe) and a thin codoped layer consisted of N, N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine (NPB) as a host of yellow light-emitting layer doped with 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB) were investigated. With appropriate tuning in the film thickness, position, and dopant concentration of the co-doped layer, a white OLED with a luminance yield of 10.02 cd/A with the CIE coordinates of (0.29, 0.33) has been achieved at a bias voltage of 9 V and a luminance level of over 10,000 cd/m2. By introducing the PIN structure with both HIL and bis(10- hydroxybenzo-quinolinato)-beryllium (BeBq2) ETL, the power efficiency of white OLED was improved.

Relationships between brightness of nighttime lights and population density

Science.gov (United States)

Naizhuo, Z.

2012-12-01

Brightness of nighttime lights has been proven to be a good proxy for socioeconomic and demographic statistics. Moreover, the satellite nighttime lights data have been used to spatially disaggregate amounts of gross domestic product (GDP), fossil fuel carbon dioxide emission, and electric power consumption (Ghosh et al., 2010; Oda and Maksyutov, 2011; Zhao et al., 2012). Spatial disaggregations were performed in these previous studies based on assumed linear relationships between digital number (DN) value of pixels in the nighttime light images and socioeconomic data. However, reliability of the linear relationships was never tested due to lack of relative high-spatial-resolution (equal to or finer than 1 km × 1 km) statistical data. With the similar assumption that brightness linearly correlates to population, Bharti et al. (2011) used nighttime light data as a proxy for population density and then developed a model about seasonal fluctuations of measles in West Africa. The Oak Ridge National Laboratory used sub-national census population data and high spatial resolution remotely-sensed-images to produce LandScan population raster datasets. The LandScan population datasets have 1 km × 1 km spatial resolution which is consistent with the spatial resolution of the nighttime light images. Therefore, in this study I selected 2008 LandScan population data as baseline reference data and the contiguous United State as study area. Relationships between DN value of pixels in the 2008 Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) stable light image and population density were established. Results showed that an exponential function can more accurately reflect the relationship between luminosity and population density than a linear function. Additionally, a certain number of saturated pixels with DN value of 63 exist in urban core areas. If directly using the exponential function to estimate the population density for the whole brightly

High Brightness Electron Guns for Next-Generation Light Sources and Accelerators

International Nuclear Information System (INIS)

H. Bluem; M.D. Cole; J. Rathke; T. Schultheiss; A.M.M. Todd; I. Ben-Zvi; T. Srinivasan-Rao; P. Colestock; D.C. Nguyen; R.L. Wood; L. Young; D. Janssen; J. Lewellen; G. Neil; H.L. Phillips; J.P. Preble

2004-01-01

Advanced Energy Systems continues to develop advanced electron gun and injector concepts. Several of these projects have been previously described, but the progress and status of each will be updated. The project closest to completion is an all superconducting RF (SRF) gun, being developed in collaboration with the Brookhaven National Laboratory, that uses the niobium of the cavity wall itself as the photocathode material. This gun has been fabricated and will shortly be tested with beam. The cavity string for a closely-coupled DC gun and SRF cavity injector that is expected to provide beam quality sufficient for proposed ERL light sources and FELs will be assembled at the Jefferson Laboratory later this year. We are also collaboration with Los Alamos on a prototype CW normal-conducting RF gun with similar performance, that will undergo thermal testing in late 2004. Another CW SRF gun project that uses a high quantum efficiency photocathode, similar to the FZ-Rossendorf approach, has just begun. Finally, we will present the RF design and cold test results for a fully axisymmetric, ultra-high-brightness x-band RF gun

Human phase response curve to a 1 h pulse of bright white light

Science.gov (United States)

St Hilaire, Melissa A; Gooley, Joshua J; Khalsa, Sat Bir S; Kronauer, Richard E; Czeisler, Charles A; Lockley, Steven W

2012-01-01

The phase resetting response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase response curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (∼8000 lux) and to compare this PRC to a dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ∼40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–response function for the effects of light on circadian resetting. PMID:22547633

Bright light exposure reduces TH-positive dopamine neurons: implications of light pollution in Parkinson's disease epidemiology.

Science.gov (United States)

Romeo, Stefania; Viaggi, Cristina; Di Camillo, Daniela; Willis, Allison W; Lozzi, Luca; Rocchi, Cristina; Capannolo, Marta; Aloisi, Gabriella; Vaglini, Francesca; Maccarone, Rita; Caleo, Matteo; Missale, Cristina; Racette, Brad A; Corsini, Giovanni U; Maggio, Roberto

2013-01-01

This study explores the effect of continuous exposure to bright light on neuromelanin formation and dopamine neuron survival in the substantia nigra. Twenty-one days after birth, Sprague-Dawley albino rats were divided into groups and raised under different conditions of light exposure. At the end of the irradiation period, rats were sacrificed and assayed for neuromelanin formation and number of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra. The rats exposed to bright light for 20 days or 90 days showed a relatively greater number of neuromelanin-positive neurons. Surprisingly, TH-positive neurons decreased progressively in the substantia nigra reaching a significant 29% reduction after 90 days of continuous bright light exposure. This decrease was paralleled by a diminution of dopamine and its metabolite in the striatum. Remarkably, in preliminary analysis that accounted for population density, the age and race adjusted Parkinson's disease prevalence significantly correlated with average satellite-observed sky light pollution.

Exposure to bright light for several hours during the daytime lowers tympanic temperature

Science.gov (United States)

Aizawa, Seika; Tokura, H.

The present study investigates the effect on thympanic temperature of exposure to different light intensities for several hours during the daytime. Nine healthy young adult volunteers (two male, seven female) were exposed to bright light of 4000 lx or dim light of 100 lx during the daytime from 0930 to 1800 hours; the light condition was then kept at 100 lx for a further hour. Tympanic temperature was measured continuously at a neutral condition (28° C, 60% relative humidity) from 1000 to 1800 hours. Urinary samples were collected from 1100 to 1900 hours every 2 h, and melatonin excretion rate was measured by enzyme immunoassay. Of nine subjects, six showed clearly lower tympanic temperatures in the bright compared with the dim condition from 1400 to 1800 hours. Average tympanic temperatures were significantly lower in the bright than in the dim condition from 1645 to 1800 hours. Melatonin excretion rate tended to be higher in the bright than in the dim condition. It was concluded that exposure to bright light of 4000 lx during the daytime for several hours could reduce tympanic temperature, compared with that measured in dim light of 100 lx.

Exposure to bright light for several hours during the daytime lowers tympanic temperature.

Science.gov (United States)

Aizawa, S; Tokura, H

1997-11-01

The present study investigates the effect on thympanic temperature of exposure to different light intensities for several hours during the daytime. Nine healthy young adult volunteers (two male, seven female) were exposed to bright light of 4000 lx or dim light of 100 lx during the daytime from 0930 to 1800 hours; the light condition was then kept at 100 lx for a further hour. Tympanic temperature was measured continuously at a neutral condition (28 degrees C, 60% relative humidity) from 1000 to 1800 hours. Urinary samples were collected from 1100 to 1900 hours every 2 h, and melatonin excretion rate was measured by enzyme immunoassay. Of nine subjects, six showed clearly lower tympanic temperatures in the bright compared with the dim condition from 1400 to 1800 hours. Average tympanic temperatures were significantly lower in the bright than in the dim condition from 1645 to 1800 hours. Melatonin excretion rate tended to be higher in the bright than in the dim condition. It was concluded that exposure to bright light of 4000 lx during the daytime for several hours could reduce tympanic temperature, compared with that measured in dim light of 100 lx.

Bright light in elderly subjects with nonseasonal major depressive disorder: a double blind randomised clinical trial using early morning bright blue light comparing dim red light treatment

Directory of Open Access Journals (Sweden)

van Someren Eus JW

2008-07-01

Full Text Available Abstract Background Depression frequently occurs in the elderly. Its cause is largely unknown, but several studies point to disturbances of biological rhythmicity. In both normal aging, and depression, the functioning of the suprachiasmatic nucleus (SCN is impaired, as evidenced by an increased prevalence of day-night rhythm perturbations, such as sleeping disorders. Moreover, the inhibitory SCN neurons on the hypothalamus-pituitary adrenocortical axis (HPA-axis have decreased activity and HPA-activity is enhanced, when compared to non-depressed elderly. Using bright light therapy (BLT the SCN can be stimulated. In addition, the beneficial effects of BLT on seasonal depression are well accepted. BLT is a potentially safe, nonexpensive and well accepted treatment option. But the current literature on BLT for depression is inconclusive. Methods/Design This study aims to show whether BLT can reduce non-seasonal major depression in elderly patients. Randomized double blind placebo controlled trial in 126 subjects of 60 years and older with a diagnosis of major depressive disorder (MDD, DSM-IV/SCID-I. Subjects are recruited through referrals of psychiatric outpatient clinics and from case finding from databases of general practitioners and old-people homes in the Amsterdam region. After inclusion subjects are randomly allocated to the active (bright blue light vs. placebo (dim red light condition using two Philips Bright Light Energy boxes type HF 3304 per subject, from which the light bulbs have been covered with bright blue- or dim red light- permitting filters. Patients will be stratified by use of antidepressants. Prior to treatment a one-week period without light treatment will be used. At three time points several endocrinological, psychophysiological, psychometrically, neuropsychological measures are performed: just before the start of light therapy, after completion of three weeks therapy period, and three weeks thereafter. Discussion If BLT

Suppressed speckle contrast of blue light emission out of white lamp with phosphors excited by blue laser diodes for high-brightness lighting applications

Science.gov (United States)

Kinoshita, Junichi; Ikeda, Yoshihisa; Takeda, Yuji; Ueno, Misaki; Kawasaki, Yoji; Matsuba, Yoshiaki; Heike, Atsushi

2012-11-01

The speckle contrast of blue light emission out of high-brightness white lamps using phosphors excited by InGaN/GaN blue laser diodes is evaluated as a measure of coherence. As a result, speckle contrast of as low as 1.7%, the same level as a blue light emitting diode, is obtained. This implies that the original blue laser light can be converted into incoherent light through lamp structures without any dynamic mechanisms. This unique speckle-free performance is considered to be realized by multiple scattering inside the lamp structure, the multi-longitudinal mode operation of the blue laser diodes, and the use of multiple laser diodes. Such almost-incoherent white lamps can be applied for general lighting without any nuisance of speckle noise and should be categorized as lamps rather than lasers in terms of laser safety regulation.

The effect of bright light on sleepiness among rapid-rotating 12-hour shift workers.

Science.gov (United States)

Sadeghniiat-Haghighi, Khosro; Yazdi, Zohreh; Jahanihashemi, Hassan; Aminian, Omid

2011-01-01

About 20% of workers in industrialized countries are shift workers and more than half of them work on night or rotating shifts. Most night workers complain of sleepiness due to lack of adjustment of the circadian rhythm. In simulated night-work experiments, scheduled exposure to bright light has been shown to reduce these complaints. Our study assessed the effects of bright light exposure on sleepiness during night work in an industrial setting. In a cross-over design, 94 workers at a ceramic factory were exposed to either bright (2500 lux) or normal light (300 lux) during breaks on night shifts. We initiated 20-minute breaks between 24.00 and 02.00 hours. Sleepiness ratings were determined using the Stanford Sleepiness Scale at 22.00, 24.00, 02.00 and 04.00 hours. Under normal light conditions, sleepiness peaked at 02:00 hours. A significant reduction (22% compared to normal light conditions) in sleepiness was observed after workers were exposed to bright light. Exposure to bright light may be effective in reducing sleepiness among night workers.

Two- and 4-hour bright-light exposures differentially effect sleepiness and performance the subsequent night.

Science.gov (United States)

Thessing, V C; Anch, A M; Muehlbach, M J; Schweitzer, P K; Walsh, J K

1994-03-01

The effect of two durations of bright light upon sleepiness and performance during typical night shift hours was assessed. Thirty normal, healthy young adults participated in a 2-night protocol. On the 1st night subjects were exposed to bright or dim light beginning at 2400 hours, under one of the following three conditions: bright light for 4 hours, dim light for 2 hours followed by bright light for 2 hours or dim light for 4 hours. Following light exposure, subjects remained awake until 0800 hours in a dimly lit room and slept in the laboratory between 0800 and 1600 hours, during which time sleep was estimated with actigraphy. Throughout the 2nd night, the multiple sleep latency test (MSLT), simulated assembly line task (SALT) performance, and subjective sleepiness were recorded. The single, 4-hour exposure to bright light was found to significantly increase MSLT scores and improve SALT performance during the early morning hours on the night following bright-light exposure. No significant effects were noted with a 2-hour exposure. The most likely explanation for these findings is a phase delay in the circadian rhythm of sleepiness-alertness.

High-Energy Compton Scattering Light Sources

CERN Document Server

Hartemann, Fred V; Barty, C; Crane, John; Gibson, David J; Hartouni, E P; Tremaine, Aaron M

2005-01-01

No monochromatic, high-brightness, tunable light sources currently exist above 100 keV. Important applications that would benefit from such new hard x-ray sources include: nuclear resonance fluorescence spectroscopy, time-resolved positron annihilation spectroscopy, and MeV flash radiography. The peak brightness of Compton scattering light sources is derived for head-on collisions and found to scale with the electron beam brightness and the drive laser pulse energy. This gamma 2

Influences of diurnal bright or dim light exposure on urine volume in humans.

Science.gov (United States)

Hyun, Ki-Ja; Nishimura, Shinya; Tokura, Hiromi

2006-03-01

We investigated with eight healthy females if 8 hr diurnal (0700 to 1500 h) bright rather than dim light (5,000 vs. 80 lx) influenced urine volume. Environmental illuminance was made identical at all other times besides 07:00 to 15:00 h. The participants spent time at strictly regulated schedules in a bioclimatic chamber (26 degrees C, relative humidity 60%) for 57 h. Blood was drawn (2 ml) just before lunch in order to calculate Creatinine clearance (Ccr). Urine volume was significantly higher during wakefulness and the 8-h sleep period with bright rather than dim light. Ccr was significantly higher after bright light. The results were discussed in terms of suppression of the sympathetic nerve system under the influence of diurnal bright light exposure. We also discussed these in terms of physiological polymorphisms.

Night-sky brightness monitoring in Hong Kong: a city-wide light pollution assessment.

Science.gov (United States)

Pun, Chun Shing Jason; So, Chu Wing

2012-04-01

Results of the first comprehensive light pollution survey in Hong Kong are presented. The night-sky brightness was measured and monitored around the city using a portable light-sensing device called the Sky Quality Meter over a 15-month period beginning in March 2008. A total of 1,957 data sets were taken at 199 distinct locations, including urban and rural sites covering all 18 Administrative Districts of Hong Kong. The survey shows that the environmental light pollution problem in Hong Kong is severe-the urban night skies (sky brightness at 15.0 mag arcsec(- 2)) are on average ~ 100 times brighter than at the darkest rural sites (20.1 mag arcsec(- 2)), indicating that the high lighting densities in the densely populated residential and commercial areas lead to light pollution. In the worst polluted urban location studied, the night-sky at 13.2 mag arcsec(- 2) can be over 500 times brighter than the darkest sites in Hong Kong. The observed night-sky brightness is found to be affected by human factors such as land utilization and population density of the observation sites, together with meteorological and/or environmental factors. Moreover, earlier night skies (at 9:30 p.m. local time) are generally brighter than later time (at 11:30 p.m.), which can be attributed to some public and commercial lightings being turned off later at night. On the other hand, no concrete relationship between the observed sky brightness and air pollutant concentrations could be established with the limited survey sampling. Results from this survey will serve as an important database for the public to assess whether new rules and regulations are necessary to control the use of outdoor lightings in Hong Kong.

Bright-light exposure during daytime sleeping affects nocturnal melatonin secretion after simulated night work.

Science.gov (United States)

Nagashima, Shunsuke; Osawa, Madoka; Matsuyama, Hiroto; Ohoka, Wataru; Ahn, Aemi; Wakamura, Tomoko

2018-02-01

The guidelines for night and shift workers recommend that after night work, they should sleep in a dark environment during the daytime. However, staying in a dark environment during the daytime reduces nocturnal melatonin secretion and delays its onset. Daytime bright-light exposure after night work is important for melatonin synthesis the subsequent night and for maintaining the circadian rhythms. However, it is not clear whether daytime sleeping after night work should be in a dim- or a bright-light environment for maintaining melatonin secretion. The aim of this study, therefore, was to evaluate the effect of bright-light exposure during daytime sleeping on nocturnal melatonin secretion after simulated night work. Twelve healthy male subjects, aged 24.8 ± 4.6 (mean ± SD), participated in 3-day sessions under two experimental conditions, bright light or dim light, in a random order. On the first day, the subjects entered the experimental room at 16:00 and saliva samples were collected every hour between 18:00 and 00:00 under dim-light conditions. Between 00:00 and 08:00, they participated in tasks that simulated night work. At 10:00 the next morning, they slept for 6 hours under either a bright-light condition (>3000 lx) or a dim-light condition (night work were compared between the light conditions using paired t-tests. The ANOVA results indicated a significant interaction (light condition and3 day) (p = .006). Post hoc tests indicated that in the dim-light condition, the melatonin concentration was significantly lower on the second day than on the first day (p = .046); however, in the bright-light condition, there was no significant difference in the melatonin concentration between the days (p = .560). There was a significant difference in ΔDLMO between the conditions (p = .015): DLMO after sleeping was advanced by 11.1 ± 17.4 min under bright-light conditions but delayed for 7.2 ± 13.6 min after sleeping under dim-light conditions. No

Recent advances in high-brightness electron guns at AES

International Nuclear Information System (INIS)

Bluem, H.; Todd, A.M.M.; Cole, M.D.; Rathke, J.; Schultheiss, T.

2003-01-01

We describe a number of active Advanced Energy Systems projects pertaining to the development of advanced, high-brightness electron guns for various applications. These projects include a fully superconducting, CW RF gun, nearing test, that utilizes the niobium surface as the photocathode material. An integrated 100 mA, low emittance DC/SRF gun, ideal as an injector for ERL-type light sources and intended as the injector for a 100 kW FEL, is in late design stage. A parallel high-power, CW, normal-conducting L-band RF gun project has just begun. The early performance analysis for this gun also shows good promise as an injector for ERL-type light sources. Lastly, a fully axisymmetric RF gun, operating in X-band, is being studied as a source of extremely bright electron bunches

Bright-light intervention induces a dose-dependent increase in striatal response to risk in healthy volunteers

DEFF Research Database (Denmark)

Macoveanu, Julian; Fisher, Patrick M; Madsen, Martin K

2016-01-01

Bright-light interventions have successfully been used to reduce depression symptoms in patients with seasonal affective disorder, a depressive disorder most frequently occurring during seasons with reduced daylight availability. Yet, little is known about how light exposure impacts human brain...... function, for instance on risk taking, a process affected in depressive disorders. Here we examined the modulatory effects of bright-light exposure on brain activity during a risk-taking task. Thirty-two healthy male volunteers living in the greater Copenhagen area received 3weeks of bright......-light intervention during the winter season. Adopting a double-blinded dose-response design, bright-light was applied for 30minutes continuously every morning. The individual dose varied between 100 and 11.000lx. Whole-brain functional MRI was performed before and after bright-light intervention to probe how...

Human responses to bright light of different durations.

Science.gov (United States)

Chang, Anne-Marie; Santhi, Nayantara; St Hilaire, Melissa; Gronfier, Claude; Bradstreet, Dayna S; Duffy, Jeanne F; Lockley, Steven W; Kronauer, Richard E; Czeisler, Charles A

2012-07-01

Light exposure in the early night induces phase delays of the circadian rhythm in melatonin in humans. Previous studies have investigated the effect of timing, intensity, wavelength, history and pattern of light stimuli on the human circadian timing system. We present results from a study of the duration–response relationship to phase-delaying bright light. Thirty-nine young healthy participants (16 female; 22.18±3.62 years) completed a 9-day inpatient study. Following three baseline days, participants underwent an initial circadian phase assessment procedure in dim light (light pulse (∼10,000 lux) of 0.2 h, 1.0 h, 2.5 h or 4.0 h duration during a 4.5 h controlled-posture episode centred in a 16 h wake episode. After another 8 h sleep episode, participants completed a second circadian phase assessment. Phase shifts were calculated from the difference in the clock time of the dim light melatonin onset (DLMO) between the initial and final phase assessments. Exposure to varying durations of bright light reset the circadian pacemaker in a dose-dependent, non-linear manner. Per minute of exposure, the 0.2 h duration was over 5 times more effective at phase delaying the circadian pacemaker (1.07±0.36 h) as compared with the 4.0 h duration (2.65±0.24 h). Acute melatonin suppression and subjective sleepiness also had a dose-dependent response to light exposure duration. These results provide strong evidence for a non-linear resetting response of the human circadian pacemaker to light duration.

High-brightness semipolar (2021¯) blue InGaN/GaN superluminescent diodes for droop-free solid-state lighting and visible-light communications

KAUST Repository

Shen, Chao

2016-05-25

A high-brightness, droop-free, and speckle-free InGaN/GaN quantum well blue superluminescent diode (SLD) was demonstrated on a semipolar (2021) GaN substrate. The 447-nm emitting SLD has a broad spectral linewidth of 6.3 nm at an optical power of 123 mW. A peak optical power of 256 mW was achieved at 700 mA CW injection current. By combining YAG:Ce phosphor, SLD-generated white light shows a color-rendering index (CRI) of 68.9 and a correlated color temperature (CCT) of 4340 K. The measured frequency response of the SLD revealed a -3 dB bandwidth of 560 MHz, thus demonstrating the feasibility of the device for both solid-state lighting (SSL) and visible-light communication (VLC) applications. © 2016 Optical Society of America.

High-brightness semipolar (2021¯) blue InGaN/GaN superluminescent diodes for droop-free solid-state lighting and visible-light communications

KAUST Repository

Shen, Chao; Ng, Tien Khee; Leonard, John T.; Pourhashemi, Arash; Nakamura, Shuji; DenBaars, Steven P.; Speck, James S.; Alyamani, Ahmed Y.; El-desouki, Munir M.; Ooi, Boon S.

2016-01-01

A high-brightness, droop-free, and speckle-free InGaN/GaN quantum well blue superluminescent diode (SLD) was demonstrated on a semipolar (2021) GaN substrate. The 447-nm emitting SLD has a broad spectral linewidth of 6.3 nm at an optical power of 123 mW. A peak optical power of 256 mW was achieved at 700 mA CW injection current. By combining YAG:Ce phosphor, SLD-generated white light shows a color-rendering index (CRI) of 68.9 and a correlated color temperature (CCT) of 4340 K. The measured frequency response of the SLD revealed a -3 dB bandwidth of 560 MHz, thus demonstrating the feasibility of the device for both solid-state lighting (SSL) and visible-light communication (VLC) applications. © 2016 Optical Society of America.

Bright light treatment as add-on therapy for depression in 28 adolescents: a randomized trial.

Science.gov (United States)

Niederhofer, Helmut; von Klitzing, Kai

2011-01-01

In the last decade, a significant incidence of depression in the younger population has been observed. Bright light therapy, an effective therapeutic option for depressed adults, could also provide safe, economical, and effective rapid recovery in adolescents. The randomized trial included 28 inpatients (18 females and 10 males) between 14 and 17 years old with depressive complaints. The study was conducted between February and December of 2010 in Rodewisch, Germany. Half of the patients (n = 14) first received placebo (50 lux) 1 hour a day in the morning from 9:00 am to 10:00 am for 1 week and then received bright light therapy (2,500 lux) for 1 week in the morning from 9:00 am to 10:00 am. The other half (n = 14) first received bright light therapy and then received placebo. Patients were encouraged to continue ongoing treatment (fluoxetine 20 mg/day and 2 sessions of psychotherapy/week) because there were no changes in medication/dosage and psychotherapy since 1 month before the 4-week study period. For assessment of depressive symptoms, the Beck Depression Inventory (BDI) was administered 1 week before and 1 day before placebo treatment, on the day between placebo and bright light treatment, and on the day after and 1 week after bright light treatment. Saliva samples of melatonin and cortisol were collected at 8:00 am and 8:00 pm 1 week before and 1 day before placebo treatment, on the day between placebo and bright light treatment, on the day after bright light treatment, and 1 week after bright light treatment and were assayed for melatonin and cortisol to observe any change in circadian timing. The BDI scores improved significantly (P = .015). The assays of saliva showed significant differences between treatment and placebo for evening melatonin (P = .040). No significant adverse reactions were observed. Antidepressant response to bright light treatment in this age group was statistically superior to placebo. World Health Organization International Clinical

Fabrication of high-brightness GaN-based light-emitting diodes via thermal nanoimprinting of ZnO-nanoparticle-dispersed resin

International Nuclear Information System (INIS)

Byeon, Kyeong-Jae; Cho, Joong-Yeon; Jo, Han-Byeol; Lee, Heon

2015-01-01

Highlights: • A various high-refractive-index ZnO patterns were formed on LED using imprinting. • Mechanism of light extraction enhancement was demonstrated by simulation and EL. • Light output power of patterned LED was improved up 19.6% by light waveguide effect. - Abstract: We fabricated high-brightness GaN-based light-emitting diodes (LEDs) with highly refractive patterned structures by using a thermal nanoimprint lithography (NIL). A highly refractive ZnO-nanoparticle-dispersed resin (ZNDR) was used in NIL, and a submicron hole, a submicron high-aspect-ratio pillar, and microconvex arrays were fabricated on the indium tin oxide (ITO) top electrode of GaN-based LED devices. We analyzed the light extraction mechanism for each of the three types of patterns by using a finite element method simulation, and found that the high-aspect-ratio pillar had a great ability to improve light extraction owing to its waveguide effect and prominent scattering effect. As a result, the light output power, which was measured in an integrating sphere, of the LED device was enhanced by up to 19.6% when the high-aspect-ratio pillar array was formed on the top ITO electrode of the device. Further, the electrical properties of none of the patterned LED devices fabricated using ZNDR degraded in comparison to those of bare LED devices

Kiloamp high-brightness beams

International Nuclear Information System (INIS)

Caporaso, G.J.

1987-01-01

Brightness preservation of high-current relativistic electron beams under two different types of transport is discussed. Recent progress in improving the brightness of laser-guided beams in the Advanced Test Accelerator is reviewed. A strategy for the preservation of the brightness of space-charge-dominated beams in a solenoidal transport system is presented

High cortisol awakening response is associated with an impairment of the effect of bright light therapy

DEFF Research Database (Denmark)

Martiny, Klaus Per Juul; Lunde, Marianne Anita; Undén, M

2009-01-01

OBJECTIVE: We investigated the predictive validity of the cortisol awakening response (CAR) in patients with non-seasonal major depression. METHOD: Patients were treated with sertraline in combination with bright or dim light therapy for a 5-week period. Saliva cortisol levels were measured in 63...

A high brightness probe of polymer nanoparticles for biological imaging

Science.gov (United States)

Zhou, Sirong; Zhu, Jiarong; Li, Yaping; Feng, Liheng

2018-03-01

Conjugated polymer nanoparticles (CPNs) with high brightness in long wavelength region were prepared by the nano-precipitation method. Based on fluorescence resonance energy transfer (FRET) mechanism, the high brightness property of the CPNs was realized by four different emission polymers. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) displayed that the CPNs possessed a spherical structure and an average diameter of 75 nm. Analysis assays showed that the CPNs had excellent biocompatibility, good photostability and low cytotoxicity. The CPNs were bio-modified with a cell penetrating peptide (Tat, a targeted element) through covalent link. Based on the entire wave fluorescence emission, the functionalized CPNs1-4 can meet multichannel and high throughput assays in cell and organ imaging. The contribution of the work lies in not only providing a new way to obtain a high brightness imaging probe in long wavelength region, but also using targeted cell and organ imaging.

Hybrid white organic light emitting diodes with low efficiency roll-off, stable color and extreme brightness

Energy Technology Data Exchange (ETDEWEB)

Liu, Baiquan; Zou, Jianhua [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China); Su, Yueju; Gao, Dongyu [New Vision Opto-Electronic Technology Co., Ltd, Guangzhou 510640 (China); Lan, Linfeng [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China); Tao, Hong, E-mail: tao.h@scut.edu.cn [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China); Peng, Junbiao [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China)

2014-07-01

Highly efficient and bright hybrid white organic light emitting diodes (WOLEDs) based on simple architectures have been successfully fabricated and characterized. The optimized device can reach a maximum forward-viewing power efficiency (PE) of 20.2 lm/W, a peak forward-viewing current efficiency (CE) of 30.7 cd/A, an extremely high brightness of 95,683 cd/m{sup 2}, and a Commission International de l’E clairage chromaticity coordinates of (0. 436, 0.425) at 12 V. Even at the illumination-relevant brightness of 1000 cd/m{sup 2}, a forward-viewing PE of 17.0 lm/W and CE of 30.7 cd/A are obtained. Moreover, it is found that the device not only suffers slight efficiency roll-off but also exhibits a stable color during a large range of brightness, indicating that the device can satisfy the future commercial requirements. Undoubtedly, the results will be beneficial to the design of both material and device architecture for high-performance WOLEDs and next-generation solid-state lighting sources. - Highlights: • A simple HWOLED with B/O/B structure has been successfully developed. • A extremely high brigthness of 95,683 cd/m{sup 2} is obtained. • A high forward-viewing CE of 30.7 cd/A and PE of 20.2 lm/W are achieved. • Efficiency roll-off is very low and color is relatively stable.

Prophylactic treatment of seasonal affective disorder (SAD) by using light visors : Bright white or infrared light?

NARCIS (Netherlands)

Meesters, Y; Beersma, DGM; Bouhuys, AL; van den Hoofdakker, RH

1999-01-01

Background: Thirty-eight patients with SAD participated in a light visor study addressing two questions. 1. Can the development of a depressive episode be prevent ed by daily exposure to bright light started before symptom onset in early fall and continued throughout the winter? 2. Does the light

Weak evidence of bright light effects on human LH and FSH

Directory of Open Access Journals (Sweden)

Kripke Daniel F

2010-05-01

Full Text Available Abstract Background Most mammals are seasonal breeders whose gonads grow to anticipate reproduction in the spring and summer. As day length increases, secretion increases for two gonadotropins, luteinizing hormone (LH and follicle stimulating hormone (FSH. This response is largely controlled by light. Light effects on gonadotropins are mediated through effects on the suprachiasmatic nucleus and responses of the circadian system. There is some evidence that seasonal breeding in humans is regulated by similar mechanisms, and that light stimulates LH secretion, but primate responses seem complex. Methods To gain further information on effects of bright light on LH and FSH secretion in humans, we analyzed urine samples collected in three experiments conducted for other goals. First, volunteers ages 18-30 years and 60-75 commenced an ultra-short 90-min sleep-wake cycle, during which they were exposed to 3000 lux light for 3 hours at balanced times of day, repeated for 3 days. Urine samples were assayed to explore any LH phase response curve. Second, depressed participants 60-79 years of age were treated with bright light or dim placebo light for 28 days, with measurements of urinary LH and FSH before and after treatment. Third, women of ages 20-45 years with premenstrual dysphoric disorder (PMDD were treated to one 3-hour exposure of morning light, measuring LH and FSH in urine before and after the treatments. Results Two of the three studies showed significant increases in LH after light treatment, and FSH also tended to increase, but there were no significant contrasts with parallel placebo treatments and no significant time-of-day treatment effects. Conclusions These results gave some support for the hypothesis that bright light may augment LH secretion. Longer-duration studies may be needed to clarify the effects of light on human LH and FSH.

Weak evidence of bright light effects on human LH and FSH.

Science.gov (United States)

Kripke, Daniel F; Elliott, Jeffrey A; Youngstedt, Shawn D; Parry, Barbara L; Hauger, Richard L; Rex, Katharine M

2010-05-11

Most mammals are seasonal breeders whose gonads grow to anticipate reproduction in the spring and summer. As day length increases, secretion increases for two gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH). This response is largely controlled by light. Light effects on gonadotropins are mediated through effects on the suprachiasmatic nucleus and responses of the circadian system. There is some evidence that seasonal breeding in humans is regulated by similar mechanisms, and that light stimulates LH secretion, but primate responses seem complex. To gain further information on effects of bright light on LH and FSH secretion in humans, we analyzed urine samples collected in three experiments conducted for other goals. First, volunteers ages 18-30 years and 60-75 commenced an ultra-short 90-min sleep-wake cycle, during which they were exposed to 3000 lux light for 3 hours at balanced times of day, repeated for 3 days. Urine samples were assayed to explore any LH phase response curve. Second, depressed participants 60-79 years of age were treated with bright light or dim placebo light for 28 days, with measurements of urinary LH and FSH before and after treatment. Third, women of ages 20-45 years with premenstrual dysphoric disorder (PMDD) were treated to one 3-hour exposure of morning light, measuring LH and FSH in urine before and after the treatments. Two of the three studies showed significant increases in LH after light treatment, and FSH also tended to increase, but there were no significant contrasts with parallel placebo treatments and no significant time-of-day treatment effects. These results gave some support for the hypothesis that bright light may augment LH secretion. Longer-duration studies may be needed to clarify the effects of light on human LH and FSH.

All-sky brightness monitoring of light pollution with astronomical methods.

Science.gov (United States)

Rabaza, O; Galadí-Enríquez, D; Estrella, A Espín; Dols, F Aznar

2010-06-01

This paper describes a mobile prototype and a protocol to measure light pollution based on astronomical methods. The prototype takes three all-sky images using BVR filters of the Johnson-Cousins astronomical photometric system. The stars are then identified in the images of the Hipparcos and General Catalogue of Photometric Data II astronomical catalogues, and are used as calibration sources. This method permits the measurement of night-sky brightness and facilitates an estimate of which fraction is due to the light up-scattered in the atmosphere by a wide variety of man-made sources. This is achieved by our software, which compares the sky background flux to that of many stars of known brightness. The reduced weight and dimensions of the prototype allow the user to make measurements from virtually any location. This prototype is capable of measuring the sky distribution of light pollution, and also provides an accurate estimate of the background flux at each photometric band. (c) 2010 Elsevier Ltd. All rights reserved.

High-brightness beamline for x-ray spectroscopy at the ALS

Energy Technology Data Exchange (ETDEWEB)

Perera, R.C.C.; Jones, G. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States); Lindle, D.W. [Univ. of Nevada, Las Vegas, NV (United States)

1997-04-01

Beamline 9.3.1 at the Advanced Light Source (ALS) is a windowless beamline, covering the 1-6 keV photon-energy range, designed to achieve the goals of high energy resolution, high flux, and high brightness at the sample. When completed later this year, it will be the first ALS monochromatic hard x-ray beamline, and its brightness will be an order of magnitude higher than presently available in this energy range. In addition, it will provide flux and resolution comparable to any other beamline now in operation. To achieve these goals, two technical improvements, relative to existing x-ray beamlines, were incorporated. First, a somewhat novel optical design for x-rays, in which matched toroidal mirrors are positioned before and after the double-crystal monochromator, was adopted. This configuration allows for high resolution by passing a collimated beam through the monochromator, and for high brightness by focusing the ALS source on the sample with unit magnification. Second, a new {open_quotes}Cowan type{close_quotes} double-crystal monochromator based on the design used at NSLS beamline X-24A was developed. The measured mechanical precision of this new monochromator shows significant improvement over existing designs, without using positional feedback available with piezoelectric devices. Such precision is essential because of the high brightness of the radiation and the long distance (12 m) from the source (sample) to the collimating (focusing) mirror. This combination of features will provide a bright, high resolution, and stable x-ray beam for use in the x-ray spectroscopy program at the ALS.

Trials of bright light exposure and melatonin administration in a patient with non-24 hour sleep-wake syndrome.

Science.gov (United States)

Hayakawa, T; Kamei, Y; Urata, J; Shibui, K; Ozaki, S; Uchiyama, M; Okawa, M

1998-04-01

We report a patient with non-24 h sleep-wake syndrome (non-24) whose free-running sleep-wake cycle was successfully treated with both scheduled bright light exposure and melatonin treatment. In the present study, morning bright light as well as evening melatonin phase-advanced sleep-wake cycles and melatonin rhythm. Both these procedures achieved appropriate entrainment to a 24 h day. However, the patient did not continue morning bright light therapy after the discharge. Rising at appropriate times in the morning for bright light therapy was difficult for him to continue. Melatonin treatment was better tolerated because of its ease of application.

Smart light random memory sprays Retinex: a fast Retinex implementation for high-quality brightness adjustment and color correction.

Science.gov (United States)

Banić, Nikola; Lončarić, Sven

2015-11-01

Removing the influence of illumination on image colors and adjusting the brightness across the scene are important image enhancement problems. This is achieved by applying adequate color constancy and brightness adjustment methods. One of the earliest models to deal with both of these problems was the Retinex theory. Some of the Retinex implementations tend to give high-quality results by performing local operations, but they are computationally relatively slow. One of the recent Retinex implementations is light random sprays Retinex (LRSR). In this paper, a new method is proposed for brightness adjustment and color correction that overcomes the main disadvantages of LRSR. There are three main contributions of this paper. First, a concept of memory sprays is proposed to reduce the number of LRSR's per-pixel operations to a constant regardless of the parameter values, thereby enabling a fast Retinex-based local image enhancement. Second, an effective remapping of image intensities is proposed that results in significantly higher quality. Third, the problem of LRSR's halo effect is significantly reduced by using an alternative illumination processing method. The proposed method enables a fast Retinex-based image enhancement by processing Retinex paths in a constant number of steps regardless of the path size. Due to the halo effect removal and remapping of the resulting intensities, the method outperforms many of the well-known image enhancement methods in terms of resulting image quality. The results are presented and discussed. It is shown that the proposed method outperforms most of the tested methods in terms of image brightness adjustment, color correction, and computational speed.

The "Brightness Rules" Alternative Conception for Light Bulb Circuits

Science.gov (United States)

Bryan, Joel A.; Stuessy, Carol

2006-01-01

An alternative conception for the observed differences in light bulb brightness was revealed during an unguided inquiry investigation in which prospective elementary teachers placed identical bulbs in series, parallel, and combination direct current circuits. Classroom observations, document analyses, and video and audio transcriptions led to the…

Bright Light for Weight Loss: Results of a Controlled Crossover Trial

Directory of Open Access Journals (Sweden)

Konstantin V. Danilenko

2013-02-01

Full Text Available Objective: To investigate whether bright light treatment can reduce body mass in overweight subjects irrespective of their seasonal (= light dependence. Methods: A crossover, placebo-controlled, randomized clinical trial was performed between November and April in Novosibirsk, Russia (55° N. The trial comprised a 3-week in-home session of morning bright light treatment using a device of light-emitting diodes and a 3-week placebo session by means of a deactivated ion generator, separated by an off-protocol period of at least 23 days. The number of placebo and light sessions was matched with respect to season. Data were obtained from 34 overweight women, aged 20-54 years, 10 were seasonal-dependent according to the Seasonal Pattern Assessment Questionnaire. Weekly measures included body weight, percentage body fat by bioimpedancemetry, and subjective scores (appetite, mood, energy levels. Results: Motivation and expectation towards weight loss were similar for the two intervention sessions. With light, compared to the placebo session, weight did not reduce significantly, but percentage fat, fat mass, and appetite were significantly lower (average fat reduction 0.35 kg. The latter two results remained significant after excluding seasonal-dependent subjects from the analysis. Irrespective of the type of intervention, seasonal-dependent subjects had greater weight and fat mass changes during treatment (decline p 0.036 or between sessions (regain p 0.003. Photoperiod (p = 0.0041, air temperature to a lesser extent (p = 0.012, but not sunshine (p = 0.29 was associated with the weight change (greater weight reduction if the second session was in spring. Conclusion: Morning bright light treatment reduces body fat and appetite in overweight women and may be included in weight control programs.

Three-Week Bright-Light Intervention Has Dose-Related Effects on Threat-Related Corticolimbic Reactivity and Functional Coupling

DEFF Research Database (Denmark)

Fisher, Patrick M; Madsen, Martin K; Mc Mahon, Brenda

2014-01-01

environmental stimuli (e.g., threat) and may underlie these effects. Serotonin signaling modulates this circuit and is implicated in the pathophysiology of seasonal and other affective disorders. METHODS: We evaluated the effects of a bright-light intervention protocol on threat-related corticolimbic reactivity......-related amygdala and prefrontal reactivity in a dose-dependent manner. Conversely, amygdala-prefrontal and intraprefrontal functional coupling increased significantly in a dose-dependent manner. Genotype status significantly moderated bright-light intervention effects on intraprefrontal functional coupling....... CONCLUSIONS: This is the first study to evaluate the effects of clinically relevant bright-light intervention on threat-related brain function. We show that amygdala-prefrontal reactivity and communication are significantly affected by bright-light intervention, an effect partly moderated by genotype...

High-brightness rf linear accelerators

International Nuclear Information System (INIS)

Jameson, R.A.

1986-01-01

The issue of high brightness and its ramifications in linacs driven by radio-frequency fields is discussed. A history of the RF linacs is reviewed briefly. Some current applications are then examined that are driving progress in RF linacs. The physics affecting the brightness of RF linacs is then discussed, followed by the economic feasibility of higher brightness machines

Efficient and bright organic light-emitting diodes on single-layer graphene electrodes

Science.gov (United States)

Li, Ning; Oida, Satoshi; Tulevski, George S.; Han, Shu-Jen; Hannon, James B.; Sadana, Devendra K.; Chen, Tze-Chiang

2013-08-01

Organic light-emitting diodes are emerging as leading technologies for both high quality display and lighting. However, the transparent conductive electrode used in the current organic light-emitting diode technologies increases the overall cost and has limited bendability for future flexible applications. Here we use single-layer graphene as an alternative flexible transparent conductor, yielding white organic light-emitting diodes with brightness and efficiency sufficient for general lighting. The performance improvement is attributed to the device structure, which allows direct hole injection from the single-layer graphene anode into the light-emitting layers, reducing carrier trapping induced efficiency roll-off. By employing a light out-coupling structure, phosphorescent green organic light-emitting diodes exhibit external quantum efficiency >60%, while phosphorescent white organic light-emitting diodes exhibit external quantum efficiency >45% at 10,000 cd m-2 with colour rendering index of 85. The power efficiency of white organic light-emitting diodes reaches 80 lm W-1 at 3,000 cd m-2, comparable to the most efficient lighting technologies.

Bright versus dim ambient light affects subjective well-being but not serotonin-related biological factors.

Science.gov (United States)

Stemer, Bettina; Melmer, Andreas; Fuchs, Dietmar; Ebenbichler, Christoph; Kemmler, Georg; Deisenhammer, Eberhard A

2015-10-30

Light falling on the retina is converted into an electrical signal which stimulates serotonin synthesis. Previous studies described an increase of plasma and CNS serotonin levels after bright light exposure. Ghrelin and leptin are peptide hormones which are involved in the regulation of hunger/satiety and are related to serotonin. Neopterin and kynurenine are immunological markers which are also linked to serotonin biosynthesis. In this study, 29 healthy male volunteers were exposed to bright (5000lx) and dim (50lx) light conditions for 120min in a cross-over manner. Subjective well-being and hunger as well as various serotonin associated plasma factors were assessed before and after light exposure. Subjective well-being showed a small increase under bright light and a small decrease under dim light, resulting in a significant interaction between light condition and time. Ghrelin concentrations increased significantly under both light conditions, but there was no interaction between light and time. Correspondingly, leptin decreased significantly under both light conditions. Hunger increased significantly with no light-time interaction. We also found a significant decrease of neopterin, tryptophan and tyrosine levels, but no interaction between light and time. In conclusion, ambient light was affecting subjective well-being rather than serotonin associated biological factors. Copyright © 2015. Published by Elsevier Ireland Ltd.

Bright green light treatment of depression for older adults [ISRCTN69400161

OpenAIRE

Loving, Richard T; Kripke, Daniel F; Knickerbocker, Nancy C; Grandner, Michael A

2005-01-01

Abstract Background Bright white light has been successfully used for the treatment of depression. There is interest in identifying which spectral colors of light are the most efficient in the treatment of depression. It is theorized that green light could decrease the intensity duration of exposure needed. Late Wake Treatment (LWT), sleep deprivation for the last half of one night, is associated with rapid mood improvement which has been sustained by light treatment. Because spectral respons...

Technological Challenges for High-Brightness Photo-Injectors

CERN Multimedia

Suberlucq, Guy

2004-01-01

Many applications, from linear colliders to free-electron lasers, passing through light sources and many other electron sources, require high brightness electron beams, usually produced by photo-injectors. Because certain parameters of these applications differ by several orders of magnitude, various solutions were implemented for the design and construction of the three main parts of the photo-injectors: lasers, photocathodes and guns. This paper summarizes the different requirements, how they lead to technological challenges and how R&D programs try to overcome these challenges. Some examples of state-of-the-art parts are presented.

Teradiode's high brightness semiconductor lasers

Science.gov (United States)

Huang, Robin K.; Chann, Bien; Burgess, James; Lochman, Bryan; Zhou, Wang; Cruz, Mike; Cook, Rob; Dugmore, Dan; Shattuck, Jeff; Tayebati, Parviz

2016-03-01

TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.

Bright light treatment of depression for older adults [ISRCTN55452501

Directory of Open Access Journals (Sweden)

Knickerbocker Nancy C

2005-11-01

Full Text Available Abstract Background The incidence of insomnia and depression in the elder population is significant. It is hoped that use of light treatment for this group could provide safe, economic, and effective rapid recovery. Methods In this home-based trial we treated depressed elderly subjects with bright white (8,500 Lux and dim red ( Results Eighty-one volunteers, between 60 and 79 years old, completed the study. Both treatment and placebo groups experienced mood improvement. Average GDS scores improved 5 points, the Hamilton Depression Rating Scale (HDRS 17 scores (extracted from the self-rated SIGH-SAD-SR improved 6 points. There were no significant treatment effects or time-by-treatment interactions. No significant adverse reactions were observed in either treatment group. The assays of urine and saliva showed no significant differences between the treatment and placebo groups. The healthy control group was active earlier and slept earlier but received less light than the depressed group at baseline. Conclusion Antidepressant response to bright light treatment in this age group was not statistically superior to placebo. Both treatment and placebo groups experienced a clinically significant overall improvement of 16%.

Bright-light effects on cognitive performance in elderly persons working simulated night shifts: psychological well-being as a mediator?

Science.gov (United States)

Kretschmer, Veronika; Schmidt, Klaus-Helmut; Griefahn, Barbara

2013-11-01

The present study examined whether the relationship between light exposure and cognitive functioning is mediated by psychological well-being in elderly persons working night shifts. The role of psychological well-being has been neglected so far in the relationship between bright light and cognitive performance. Sleepiness and mood were applied as indicators of psychological well-being. Cognitive functioning was examined in terms of concentration, working memory, and divided attention. A total of thirty-two test persons worked in three consecutive simulated night shifts, 16 under bright light (3,000 lux) and 16 under room light (300 lux). Concentration, working memory, and divided attention were measured by computerised tasks. The hypothesised mediators were recorded by questionnaires. Mediation analyses were conducted for estimating direct, total, and indirect effects in simple mediation models. Results indicate that sleepiness and mood did not function as mediators in the prediction of concentration, working memory, and/or divided attention by light exposure. Sleepiness led to an underestimation of the positive bright-light effect on concentration performance. Mood showed only a random effect due to the positive bright-light effect on working memory. Sleepiness and mood could completely be excluded as mediators in the relationship between light exposure and cognitive functioning. This study underlines that psychological well-being of elderly persons is not a critical component in the treatment of bright light on cognitive performance in the night shift workplace. In summary, it becomes evident that bright light has a strong direct and independent effect on cognitive performance, particularly on working memory and concentration.

Direct imaging of phase objects enables conventional deconvolution in bright field light microscopy.

Directory of Open Access Journals (Sweden)

Carmen Noemí Hernández Candia

Full Text Available In transmitted optical microscopy, absorption structure and phase structure of the specimen determine the three-dimensional intensity distribution of the image. The elementary impulse responses of the bright field microscope therefore consist of separate absorptive and phase components, precluding general application of linear, conventional deconvolution processing methods to improve image contrast and resolution. However, conventional deconvolution can be applied in the case of pure phase (or pure absorptive objects if the corresponding phase (or absorptive impulse responses of the microscope are known. In this work, we present direct measurements of the phase point- and line-spread functions of a high-aperture microscope operating in transmitted bright field. Polystyrene nanoparticles and microtubules (biological polymer filaments serve as the pure phase point and line objects, respectively, that are imaged with high contrast and low noise using standard microscopy plus digital image processing. Our experimental results agree with a proposed model for the response functions, and confirm previous theoretical predictions. Finally, we use the measured phase point-spread function to apply conventional deconvolution on the bright field images of living, unstained bacteria, resulting in improved definition of cell boundaries and sub-cellular features. These developments demonstrate practical application of standard restoration methods to improve imaging of phase objects such as cells in transmitted light microscopy.

Photosynthetically supplemental lighting for vegetable crop production with super-bright laser diode

Science.gov (United States)

Hu, Yongguang; Li, Pingping; Shi, Jintong

2007-02-01

Although many artificial light sources like high-pressure sodium lamp, metal halide lamp, fluorescent lamp and so on are commonly used in horticulture, they are not widely applied because of the disadvantages of unreasonable spectra, high cost and complex control. Recently new light sources of light-emitting diode (LED) and laser diode (LD) are becoming more and more popular in the field of display and illumination with the improvement of material and manufacturing, long life-span and increasingly low cost. A new type of super-bright red LD (BL650, central wavelength is 650 nm) was selected to make up of the supplemental lighting panel, on which LDs were distributed with regular hexagon array. Drive circuit was designed to power it and adjust light intensity. System performance including temperature rise and light intensity distribution under different vertical/horizontal distances were tested. Photosynthesis of sweet pepper and eggplant leaf under LD was measured with LI-6400 to show the supplemental lighting effects. The results show that LD system can supply the maximum light intensity of 180 μmol/m2 •s at the distance of 50 mm below the panel and the temperature rise is little within 1 °C. Net photosynthetic rate became faster when LD system increased light intensity. Compared with sunlight and LED supplemental lighting system, LD's promotion on photosynthesis is in the middle. Thus it is feasible for LD light source to supplement light for vegetable crops. Further study would focus on the integration of LD and other artificial light sources.

Does low surface brightness mean low density?

NARCIS (Netherlands)

deBlok, WJG; McGaugh, SS

1996-01-01

We compare the dynamical properties of two galaxies at identical positions on the Tully-Fisher relation, but with different surface brightnesses. We find that the low surface brightness galaxy UGC 128 has a higher mass-to-light ratio, and yet has lower mass densities than the high surface brightness

High brightness semiconductor lasers with reduced filamentation

DEFF Research Database (Denmark)

McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.

1999-01-01

High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture...

Modal evaluation of the anthropogenic night sky brightness at arbitrary distances from a light source

International Nuclear Information System (INIS)

Bará, Salvador; Ribas, Salvador J; Kocifaj, Miroslav

2015-01-01

The artificial emissions of light contribute to a high extent to the observed brightness of the night sky in many places of the world. Determining the all-sky radiance of anthropogenic origin requires solving the radiative transfer equation for ground-level light sources, generally resorting to a double-scattering approximation in order to account for the observed radiance patterns with a reasonable degree of accuracy. Since the all-sky radiance distribution produced by an elementary light source depends on the distance to the observer in a way that is not immediately obvious, the contributions of sources located at different distances have to be computed on an individual basis, solving for each one the corresponding scattering integrals. In this paper we show that these calculations may be significantly alleviated by using a modal approach, whereby the hemispheric night-sky radiance is expanded in terms of a convenient basis of two-dimensional (2D) orthogonal functions. Since the modal coefficients of this expansion do vary smoothly with the distance to the observer, the all-sky brightness distributions produced by light sources located at arbitrary intermediate distances can be efficiently estimated by interpolation, provided that the coefficients at a discrete set of distances are accurately determined beforehand. (paper)

Diagnostics for high-brightness beams

International Nuclear Information System (INIS)

Shafer, R.E.

1990-01-01

Special techniques are required for beam diagnostics on high-brightness particle beams. Examples of high-brightness beams include low-emittance proton linacs (either pulsed or CW), electron linacs suitable for free-electron-laser applications, and future linear colliders. Non-interceptive and minimally-interceptive techniques for measuring beam current, position, profile, and transverse and longitudinal emittance will be reviewed. Included will be stripline, wire scanner, laser neutralization, beam-beam scattering, interceptive microgratings, spontaneous emission, optical transition radiation, and other techniques. 24 refs

Plasmonic EIT-like switching in bright-dark-bright plasmon resonators.

Science.gov (United States)

Chen, Junxue; Wang, Pei; Chen, Chuncong; Lu, Yonghua; Ming, Hai; Zhan, Qiwen

2011-03-28

In this paper we report the study of the electromagnetically induced transparency (EIT)-like transmission in the bright-dark-bright plasmon resonators. It is demonstrated that the interferences between the dark plasmons excited by two bright plasmon resonators can be controlled by the incident light polarization. The constructive interference strengthens the coupling between the bright and dark resonators, leading to a more prominent EIT-like transparency window of the metamaterial. In contrary, destructive interference suppresses the coupling between the bright and dark resonators, destroying the interference pathway that forms the EIT-like transmission. Based on this observation, the plasmonic EIT switching can be realized by changing the polarization of incident light. This phenomenon may find applications in optical switching and plasmon-based information processing.

Recognizing emotions in faces : effects of acute tryptophan depletion and bright light

NARCIS (Netherlands)

aan het Rot, Marije; Coupland, Nicholas; Boivin, Diane B.; Benkelfat, Chawki; Young, Simon N.

2010-01-01

In healthy never-depressed individuals, acute tryptophan depletion (ATD) may selectively decrease the accurate recognition of fearful facial expressions. Here we investigated the perception of facial emotions after ATD in more detail. We also investigated whether bright light, which can reverse

Subjective time runs faster under the influence of bright rather than dim light conditions during the forenoon.

Science.gov (United States)

Morita, Takeshi; Fukui, Tomoe; Morofushi, Masayo; Tokura, Hiromi

2007-05-16

The study investigated if 6 h morning bright light exposure, compared with dim light exposure, could influence time sense (range: 5-15 s). Eight women served as participants. The participant entered a bioclimatic chamber at 10:00 h on the day before the test day, where an ambient temperature and relative humidity were controlled at 25 degrees C and 60%RH. She sat quietly in a sofa in 50 lx until 22:00 h, retired at 22:00 h and then slept in total darkness. She rose at 07:00 h the following morning and again sat quietly in a sofa till 13:00 h, either in bright (2500 lx) or dim light (50 lx), the order of light intensities between the two occasions being randomized. The time-estimation test was performed from 13:00 to 13:10 h in 200 lx. The participant estimated the time that had elapsed between two buzzers, ranging over 5-15 s, and inputting the estimate into a computer. The test was carried out separately upon each individual. Results showed that the participants estimated higher durations of the given time intervals after previous exposure to 6 h of bright rather than dim light. The finding is discussed in terms of different load errors (difference between the actual core temperature and its thermoregulatory set-point) following 6-h exposure to bright or dim light in the morning.

Thoughts About Nursing Curricula: Dark Clouds and Bright Lights.

Science.gov (United States)

Turkel, Marian C; Fawcett, Jacqueline; Amankwaa, Linda; Clarke, Pamela N; Dee, Vivien; Eustace, Rosemary; Hansell, Phyllis Shanley; Jones, Dorothy A; Smith, Marlaine C; Zahourek, Rothlyn

2018-04-01

In this essay, several nurse scholars who are particularly concerned about the contemporary state of nursing science present their concerns about the inclusion of nursing conceptual models and theories in the curricula of nursing programs (dark clouds) and ways in which the concerns have been addressed (bright lights). This essay is the second of two essays that were catalyzed by Barrett's paper, "Again, What Is Nursing Science?" The first essay was published in the previous issue of Nursing Science Quarterly.

High-brightness injector modeling

International Nuclear Information System (INIS)

Lewellen, J.W.

2004-01-01

There are many aspects to the successful conception, design, fabrication, and operation of high-brightness electron beam sources. Accurate and efficient modeling of the injector are critical to all phases of the process, from evaluating initial ideas to successful diagnosis of problems during routine operation. The basic modeling tasks will vary from design to design, according to the basic nature of the injector (dc, rf, hybrid, etc.), the type of cathode used (thermionic, photo, field emitter, etc.), and 'macro' factors such as average beam current and duty factor, as well as the usual list of desired beam properties. The injector designer must be at least aware of, if not proficient at addressing, the multitude of issues that arise from these considerations; and, as high-brightness injectors continue to move out of the laboratory, the number of such issues will continue to expand.

Single-Layer Halide Perovskite Light-Emitting Diodes with Sub-Band Gap Turn-On Voltage and High Brightness.

Science.gov (United States)

Li, Junqiang; Shan, Xin; Bade, Sri Ganesh R; Geske, Thomas; Jiang, Qinglong; Yang, Xin; Yu, Zhibin

2016-10-03

Charge-carrier injection into an emissive semiconductor thin film can result in electroluminescence and is generally achieved by using a multilayer device structure, which requires an electron-injection layer (EIL) between the cathode and the emissive layer and a hole-injection layer (HIL) between the anode and the emissive layer. The recent advancement of halide perovskite semiconductors opens up a new path to electroluminescent devices with a greatly simplified device structure. We report cesium lead tribromide light-emitting diodes (LEDs) without the aid of an EIL or HIL. These so-called single-layer LEDs have exhibited a sub-band gap turn-on voltage. The devices obtained a brightness of 591 197 cd m -2 at 4.8 V, with an external quantum efficiency of 5.7% and a power efficiency of 14.1 lm W -1 . Such an advancement demonstrates that very high efficiency of electron and hole injection can be obtained in perovskite LEDs even without using an EIL or HIL.

High Brightness HDR Projection Using Dynamic Freeform Lensing

KAUST Repository

Damberg, Gerwin

2016-05-03

Cinema projectors need to compete with home theater displays in terms of image quality. High frame rate and spatial resolution as well as stereoscopic 3D are common features today, but even the most advanced cinema projectors lack in-scene contrast and, more important, high peak luminance, both of which are essential perceptual attributes of images appearing realistic. At the same time, HDR image statistics suggest that the average image intensity in a controlled ambient viewing environment such as the cinema can be as low as 1% for cinematic HDR content and not often higher than 18%, middle gray in photography. Traditional projection systems form images and colors by blocking the source light from a lamp, therefore attenuating between 99% and 82% of light, on average. This inefficient use of light poses significant challenges for achieving higher peak brightness levels. In this work, we propose a new projector architecture built around commercially available components, in which light can be steered to form images. The gain in system efficiency significantly reduces the total cost of ownership of a projector (fewer components and lower operating cost), and at the same time increases peak luminance and improves black level beyond what is practically achievable with incumbent projector technologies. At the heart of this computational display technology is a new projector hardware design using phase modulation in combination with a new optimization algorithm that is capable of on-the-fly computation of freeform lens surfaces. © 2016 ACM.

Providing Bright-Hard X-ray Beams from a Lower Energy Light Source

Science.gov (United States)

Robin, David

2002-04-01

At the Advanced Light Source (ALS) there had been an increasing demand for more high brightness harder X-ray sources in the 7 to 40 KeV range. In response to that demand, the ALS storage ring was modified in August 2001. Three 1.3 Tesla normal conducting bending magnets were removed and replaced with three 5 Tesla superconducting magnets (Superbends). The radiation produced by these Superbends is an order of magnitude higher in photon brightness and flux at 12 keV than the 1.3 Tesla bends, making them excellent sources of harder x-rays for protein crystallography and other harder x-ray applications. At the same time the Superbends do not compromise the performance of the facility in the UV and Soft X-ray regions of the spectrum. The Superbends will eventually feed 12 new x-ray beam lines greatly enhancing the facility's capacity in the hard x-ray region. The Superbend project is the biggest upgrade to the ALS storage ring since the ring was commissioned in 1993. In this paper we present, a history of the project, details of the magnet, installation, commissioning, and resulting performance of the ALS with Superbends.

High-intensity sources for light ions

International Nuclear Information System (INIS)

Leung, K.N.

1995-10-01

The use of the multicusp plasma generator as a source of light ions is described. By employing radio-frequency induction discharge, the performance of the multicusp source is greatly improved, both in lifetime and in high brightness H + and H - beam production. A new technique for generating multiply-charged ions in this type of ion source is also presented

Application of high-brightness LEDs in aircraft position lights

Science.gov (United States)

Machi, Nicolo; Mangum, Scott; Singer, Jeffrey M.

2004-10-01

Solid state lighting devices have made their way into a number of niche markets and continue to make inroads into other markets as their price / performance ratios improve. One of these markets is aviation lighting. Although this paper will focus on the use of LEDs for aircraft position lights, much of the discussion is applicable to other installations on the interior and exterior of the aircraft. The color, light distribution and intensity levels for a position light are all closely regulated through Code of Federal Regulation (CFR; formerly Federal Aviation Regulation (FAR)) documents. These lighting requirements, along with harsh thermal and environmental requirements, drive the design. In this paper, we will look at these requirements and discuss what is required in order to use LEDs for this type of application. We will explore the optical, thermal and electrical issues associated with the use of LEDs for position lights and examine the specific case study of the Astreon forward position lights. Finally, we will discuss some of the challenges that we see with solid state lighting in current and future aircraft applications.

High brightness ion source

International Nuclear Information System (INIS)

Dreyfus, R.W.; Hodgson, R.T.

1975-01-01

A high brightness ion beam is obtainable by using lasers to excite atoms or molecules from the ground state to an ionized state in increments, rather than in one step. The spectroscopic resonances of the atom or molecule are used so that relatively long wavelength, low power lasers can be used to obtain such ion beam

Dim nighttime illumination interacts with parametric effects of bright light to increase the stability of circadian rhythm bifurcation in hamsters.

Science.gov (United States)

Evans, Jennifer A; Elliott, Jeffrey A; Gorman, Michael R

2011-07-01

The endogenous circadian pacemaker of mammals is synchronized to the environmental day by the ambient cycle of relative light and dark. The present studies assessed the actions of light in a novel circadian entrainment paradigm where activity rhythms are bifurcated following exposure to a 24-h light:dark:light:dark (LDLD) cycle. Bifurcated entrainment under LDLD reflects the temporal dissociation of component oscillators that comprise the circadian system and is facilitated when daily scotophases are dimly lit rather than completely dark. Although bifurcation can be stably maintained in LDLD, it is quickly reversed under constant conditions. Here the authors examine whether dim scotophase illumination acts to maintain bifurcated entrainment under LDLD through potential interactions with the parametric actions of bright light during the two daily photophases. In three experiments, wheel-running rhythms of Syrian hamsters were bifurcated under LDLD with dimly lit scotophases, and after several weeks, dim scotophase illumination was either retained or extinguished. Additionally, "full" and "skeleton" photophases were employed under LDLD cycles with dimly lit or completely dark scotophases to distinguish parametric from nonparametric effects of bright light. Rhythm bifurcation was more stable in full versus skeleton LDLD cycles. Dim light facilitated the maintenance of bifurcated entrainment under full LDLD cycles but did not prevent the loss of rhythm bifurcation in skeleton LDLD cycles. These studies indicate that parametric actions of bright light maintain the bifurcated entrainment state; that dim scotophase illumination increases the stability of the bifurcated state; and that dim light interacts with the parametric effects of bright light to increase the stability of rhythm bifurcation under full LDLD cycles. A further understanding of the novel actions of dim light may lead to new strategies for understanding, preventing, and treating chronobiological

Thoughts About Advancement of the Discipline: Dark Clouds and Bright Lights.

Science.gov (United States)

Turkel, Marian; Fawcett, Jacqueline; Chinn, Peggy L; Eustace, Rosemary; Hansell, Phyllis Shanley; Smith, Marlaine C; Watson, Jean; Zahourek, Rothlyn

2018-01-01

In this essay, several nurse scholars who are particularly concerned about the contemporary state of nursing science present their specific concerns (dark clouds) about the advancement of our discipline and the ways in which the concerns have been addressed (bright lights). This essay is the first of two essays that were catalyzed by Barrett's paper, "Again, What Is Nursing Science?" The second essay will be published in the next issue Nursing Science Quarterly.

Effects of a two-hour early awakening and of bright light exposure on plasma patterns of cortisol, melatonin, prolactin and testosterone in man.

Science.gov (United States)

Touitou, Y; Benoit, O; Foret, J; Aguirre, A; Bogdan, A; Clodoré, M; Touitou, C

1992-03-01

Bright light is a synchronizing agent that entrains human circadian rhythms and modifies various endocrine and neuroendocrine functions. The aim of the present study was to determine whether and how the exposure to a bright light stimulus during the 2 h following a 2 h earlier awakening could modify the disturbance induced by the the sleep deprivation on the plasma patterns of hormones whose secretion is sensitive to light and/or sleep, namely melatonin, prolactin, cortisol and testosterone. Six healthy and synchronized (lights on: 07.00-23.00) male students (22.5 +/- 1.1 years) with normal psychological profiles volunteered for the study in winter. The protocol consisted of a baseline control night (customary sleep schedule) followed by three shortened nights with a rising at 05.00 and a 2 h exposure to either dim light (50 lux; one week) or bright light (2000 lux; other week). Our study showed a phase advance of the circadian rhythm of plasma cortisol without significant modifications of the hormone mean or peak concentration. Plasma melatonin concentration decreased following bright light exposure, whereas no obvious modifications of plasma testosterone or prolactin patterns could be observed in this protocol.

Improvement in Fatigue, Sleepiness, and Health-Related Quality of Life with Bright Light Treatment in Persons with Seasonal Affective Disorder and Subsyndromal SAD

Directory of Open Access Journals (Sweden)

Cecilia Rastad

2011-01-01

Full Text Available Objective. To investigate the effects of bright light treatment for secondary outcome measures and to explore and validate empirically derived subgroups and treatment effects in subgroups. Methods. A descriptive design. A sample of forty-nine persons (mean age of 45.8 with clinically assessed seasonal affective disorder (SAD or subsyndromal SAD (S-SAD participated in a two-group clinical trial evaluating the effects of treatment with bright light therapy. A person-oriented cluster analysis was applied to study treatment effects in subgroups. Results. For the merged group, sleepiness (Epworth Sleepiness Scale, fatigue (fatigue questionnaire, and health-related quality of life (SF-36 were improved at posttreatment, and results were maintained at the one-month followup. Three distinct subgroups had a high level of fatigue in common, while the level of excessive daytime sleepiness and depressed mood differed between the subgroups. Over time, all subgroups improved following ten days treatment in a light room. Conclusion. Fatigue, excessive daytime sleepiness, and health-related quality of life improve in a similar way as depressed mood following treatment with bright light. The treatment was effective irrespective of the severity of the disorder, that is, for persons with SAD and subsyndromal SAD.

Retinal venous blood carbon monoxide response to bright light in male pigs: A preliminary study.

Science.gov (United States)

Oren, Dan A; Duda, Magdalena; Kozioł, Katarzyna; Romerowicz-Misielak, Maria; Koziorowska, Anna; Sołek, Przemysław; Nowak, Sławomir; Kulpa, Magdalena; Koziorowski, Marek

2017-03-01

The physical mechanism by which light is absorbed in the eye and has antidepressant and energizing effects in Seasonal Affective Disorder and other forms of psychiatric major depression is of scientific interest. This study was designed to explore one specific aspect of a proposed humoral phototransduction mechanism, namely that carbon monoxide (CO) levels increase in retinal venous blood in response to bright light. Eleven mature male pigs approximately six months of age were kept for 7days in darkness and fasted for 12h prior to surgery. Following mild sedation, anesthesia was induced. Silastic catheters were inserted into the dorsal nasal vein through the angular vein of the eye to reach the ophthalmic sinus, from which venous blood outflowing from the eye area was collected. The animals were exposed to 5000lx of fluorescent-generated white light. CO levels in the blood were analyzed by gas chromatography before and after 80min of light exposure. At baseline, mean CO levels in the retinal venous blood were 0.43±0.05(SE)nmol/ml. After bright light, mean CO levels increased to 0.54±0.06nmol/ml (two-tailed t-test plight exposure raises carbon monoxide levels in ophthalmic venous blood. Copyright © 2017 Elsevier B.V. All rights reserved.

The Physics and Applications of High Brightness Electron Beams

Science.gov (United States)

Palumbo, Luigi; Rosenzweig, J.; Serafini, Luca

2007-09-01

brightness photoinjector / M. Ferrario, V. Fusco, M. Migliorati and L. Palumbo. Simulations of coherent synchroton radiation effects in electron machines / M. Migliorati, A, Schiavi and G. Dattoli. QFEL: A numerical code for multi-dimensional simulation of free electron lasers in the quantum regime / A. Schiavi ... [et al.]. First simulations results on laser pulse jitter and microbunching instability at Saprxino / M. Boscolo ... [et al.]. -- Working Group 4. Working group 4 summary: applications of high brightness beams to advanced accelerators and light sources / M. Uesaka and A. Rossi. Study of transverse effects in the production of X-rays with free-electron laser based on an optical ondulator / A. Bacci ... [et al.]. Channeling projects at LNF: from crystal undulators to capillary waveguides / S.B. Dabagov ... [et al.]. Mono-Energetic electron generation and plasma diagnosis experiments in a laser plasma cathode / K. Kinoshita ... [et al.]. A high-density electron beam and quad-scan measurements at Pleiades Thompson X-ray source / J.K. Lim ... [et al.]. Laser pulse circulation system for compact monochromatic tunable hard X-ray source / H. Ogino ... [et al.]. Limits on production of narrow band photons from inverse compton scattering / J. Rosenzweig and O. Williams. Preliminary results from the UCLA/SLAC ultra-high gradient Cerenkov wakefield accelerator experiment / M.C. Thompson ... [et al.]. Status of the polarized nonlinear inverse compton scattering experiment at UCLA / O. Williams... [et al.]. Coupling laser power into a slab-symmetric accelerator structure / R.B. Yoder and J.B. Rosenzweig.

Micro-structure Engineering of InGaN/GaN Quantum Wells for High Brightness Light Emitting Devices

KAUST Repository

Shen, Chao

2013-05-01

> 3 μm in the array configuration would allow the building of practical devices. Overall, this work demonstrated a novel top-down approach to manufacture large effective-area, high brightness emitters for solid-state lighting applications.

Melatonin and bright-light treatment for rest-activity disruption in institutionalized patients with Alzheimer's disease

NARCIS (Netherlands)

Dowling, G.A.; Burr, R.L.; van Someren, E.J.W.; Hubbard, E.M.; Luxenberg, J.S.; Mastick, J.; Cooper, B.A.

2008-01-01

OBJECTIVES: To test whether the addition of melatonin to bright-light therapy enhances the efficacy in treating rest-activity (circadian) disruption in institutionalized patients with Alzheimer's disease (AD). DESIGN: Randomized, controlled trial. SETTING: Two nursing homes in San Francisco,

Very high efficiency phosphorescent organic light-emitting devices by using rough indium tin oxide

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yingjie; Aziz, Hany, E-mail: h2aziz@uwaterloo.ca [Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1 (Canada)

2014-07-07

The efficiency of organic light-emitting devices (OLEDs) is shown to significantly depend on the roughness of the indium tin oxide (ITO) anode. By using rougher ITO, light trapped in the ITO/organic wave-guided mode can be efficiently extracted, and a light outcoupling enhancement as high as 40% is achieved. Moreover, contrary to expectations, the lifetime of OLEDs is not affected by ITO roughness. Finally, an OLED employing rough ITO anode that exhibits a current efficiency of 56 cd/A at the remarkably high brightness of 10{sup 5} cd/m{sup 2} is obtained. This represents the highest current efficiency at such high brightness to date for an OLED utilizing an ITO anode, without any external light outcoupling techniques. The results demonstrate the significant efficiency benefits of using ITO with higher roughness in OLEDs.

Very high efficiency phosphorescent organic light-emitting devices by using rough indium tin oxide

International Nuclear Information System (INIS)

Zhang, Yingjie; Aziz, Hany

2014-01-01

The efficiency of organic light-emitting devices (OLEDs) is shown to significantly depend on the roughness of the indium tin oxide (ITO) anode. By using rougher ITO, light trapped in the ITO/organic wave-guided mode can be efficiently extracted, and a light outcoupling enhancement as high as 40% is achieved. Moreover, contrary to expectations, the lifetime of OLEDs is not affected by ITO roughness. Finally, an OLED employing rough ITO anode that exhibits a current efficiency of 56 cd/A at the remarkably high brightness of 10 5  cd/m 2 is obtained. This represents the highest current efficiency at such high brightness to date for an OLED utilizing an ITO anode, without any external light outcoupling techniques. The results demonstrate the significant efficiency benefits of using ITO with higher roughness in OLEDs.

Effect of morning bright light on body temperature, plasma cortisol and wrist motility measured during 24 hour of constant conditions.

Science.gov (United States)

Foret, J; Aguirre, A; Touitou, Y; Clodoré, M; Benoit, O

1993-06-11

Using 24 h constant conditions, time course of body temperature, plasma cortisol and wrist motility was measured in response to a 3 day morning 2 h bright light pulse. This protocol demonstrated that a 2000 lux illumination was sufficient to elicit a shift of about 2 h of temperature minimum and cortisol peak. In reference session, actimetric recordings showed a circadian time course, closely in relation with core temperature. Bright light pulse resulted in a decrease of amplitude and a disappearance of circadian pattern of actimetry.

Controlling excitons. Concepts for phosphorescent organic LEDs at high brightness

Energy Technology Data Exchange (ETDEWEB)

Reineke, Sebastian

2009-11-15

This work focusses on the high brightness performance of phosphorescent organic light-emitting diodes (OLEDs). The use of phosphorescent emitter molecules in OLEDs is essential to realize internal electron-photon conversion efficiencies of 100 %. However, due to their molecular nature, the excited triplet states have orders of magnitude longer time constants compared to their fluorescent counterparts which, in turn, strongly increases the probability of bimolecular annihilation. As a consequence, the efficiencies of phosphorescent OLEDs decline at high brightness - an effect known as efficiency roll-off, for which it has been shown to be dominated by triplet-triplet annihilation (TTA). In this work, TTA of the archetype phosphorescent emitter Ir(ppy){sub 3} is investigated in time-resolved photoluminescence experiments. For the widely used mixed system CBP:Ir(ppy){sub 3}, host-guest TTA - an additional unwanted TTA channel - is experimentally observed at high excitation levels. By using matrix materials with higher triplet energies, this effect is efficiently suppressed, however further studies show that the efficiency roll-off of Ir(ppy)3 is much more pronounced than predicted by a model based on Foerster-type energy transfer, which marks the intrinsic limit for TTA. These results suggest that the emitter molecules show a strong tendency to form aggregates in the mixed film as the origin for enhanced TTA. Transmission electron microscopy images of Ir(ppy){sub 3} doped mixed films give direct proof of emitter aggregates. Based on these results, two concepts are developed that improve the high brightness performance of OLEDs. In a first approach, thin intrinsic matrix interlayers are incorporated in the emission layer leading to a one-dimensional exciton confinement that suppresses exciton migration and, consequently, TTA. The second concept reduces the efficiency roll-off by using an emitter molecule with slightly different chemical structure, i.e. Ir(ppy){sub 2

High-brightness electron beams for production of high intensity, coherent radiation for scientific and industrial applications

International Nuclear Information System (INIS)

Kim, K.-J.

1999-01-01

Relativistic electron beams with high six-dimensional phase space densities, i.e., high-brightness beams, are the basis for efficient generation of intense and coherent radiation beams for advanced scientific and industrial applications. The remarkable progress in synchrotrons radiation facilities from the first generation to the current, third-generation capability illustrates this point. With the recent development of the high-brightness electron gun based on laser-driven rf photocathodes, linacs have become another important option for high-brightness electron beams. With linacs of about 100 MeV, megawatt-class infrared free-electron lasers can be designed for industrial applications such as power beaming. With linacs of about 10 GeV, 1- angstrom x-ray beams with brightness and time resolution exceeding by several orders of magnitude the current synchrotrons radiation sources can be generated based on self-amplified spontaneous emission. Scattering of a high-brightness electron beam by high power laser beams is emerging as a compact method of generating short-pulse, bright x-rays. In the high-energy frontier, photons of TeV quantum energy could be generated by scattering laser beams with TeV electron beams in future linear colliders

Design of a high-power, high-brightness Nd:YAG solar laser.

Science.gov (United States)

Liang, Dawei; Almeida, Joana; Garcia, Dário

2014-03-20

A simple high-power, high-brightness Nd:YAG solar laser pumping approach is presented in this paper. The incoming solar radiation is both collected and concentrated by four Fresnel lenses and redirected toward a Nd:YAG laser head by four plane-folding mirrors. A fused-silica secondary concentrator is used to compress the highly concentrated solar radiation to a laser rod. Optimum pumping conditions and laser resonator parameters are found through ZEMAX and LASCAD numerical analysis. Solar laser power of 96 W is numerically calculated, corresponding to the collection efficiency of 24  W/m². A record-high solar laser beam brightness figure of merit of 9.6 W is numerically achieved.

Apigenin-7-diglucuronide protects retinas against bright light-induced photoreceptor degeneration through the inhibition of retinal oxidative stress and inflammation.

Science.gov (United States)

Bian, Minjuan; Zhang, Yong; Du, Xiaoye; Xu, Jing; Cui, Jingang; Gu, Jiangping; Zhu, Weiliang; Zhang, Teng; Chen, Yu

2017-05-15

Vision impairment in retinal degenerative diseases such as age-related macular degeneration is primarily associated with photoreceptor degeneration, in which oxidative stress and inflammatory responses are mechanistically involved as central players. Therapies with photoreceptor protective properties remain to be developed. Apigenin-7-diglucuronide (A7DG), a flavonoid glycoside, is present in an assortment of medicinal plants with anti-inflammatory or ant-oxidant activities. However, the pharmacological significance of A7DG remains unknown in vivo. The current study isolated A7DG from Glechoma longituba (Nakai) Kuprian and investigated the retinal protective effect A7DG in mice characterized by bright light-induced photoreceptor degeneration. The results showed that A7DG treatment led to remarkable photoreceptor protection in bright light-exposed BALB/c mice. Moreover, A7DG treatment alleviated photoreceptor apoptosis, mitigated oxidative stress, suppressed reactive gliosis and microglial activation and attenuated the expression of proinflammatory genes in bright light-exposed retinas. The results demonstrated for the first time remarkable photoreceptor protective activities of A7DG in vivo. Inhibition of bright light-induced retinal oxidative stress and retinal inflammatory responses was associated with the retinal protection conferred by A7DG. The work here warrants further evaluation of A7DG as a pharmacological candidate for the treatment of vision-threatening retinal degenerative disorders. Moreover, given the general implication of oxidative stress and inflammation in the pathogenesis of neurodegeneration, A7DG could be further tested for the treatment of other neurodegenerative disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

High-brightness H/sup -/ accelerators

International Nuclear Information System (INIS)

Jameson, R.A.

1987-01-01

Neutral particle beam (NPB) devices based on high-brightness H/sup -/ accelerators are an important component of proposed strategic defense systems. The basic rational and R and D program are outlined and examples given of the underlying technology thrusts toward advanced systems. Much of the research accomplished in the past year is applicable to accelerator systems in general; some of these activities are discussed

Measuring and mapping the night sky brightness of Perth, Western Australia

Science.gov (United States)

Biggs, James D.; Fouché, Tiffany; Bilki, Frank; Zadnik, Marjan G.

2012-04-01

In order to study the light pollution produced in the city of Perth, Western Australia, we have used a hand-held sky brightness meter to measure the night sky brightness across the city. The data acquired facilitated the creation of a contour map of night sky brightness across the 2400 km2 area of the city - the first such map to be produced for a city. Importantly, this map was created using a methodology borrowed from the field of geophysics - the well proven and rigorous techniques of geostatistical analysis and modelling. A major finding of this study is the effect of land use on night sky brightness. By overlaying the night sky brightness map on to a suitably processed Landsat satellite image of Perth we found that locations near commercial and/or light industrial areas have a brighter night sky, whereas locations used for agriculture or having high vegetation coverage have a fainter night sky than surrounding areas. Urban areas have intermediate amounts of vegetation and are intermediate in brightness compared with the above-mentioned land uses. Regions with a higher density of major highways also appear to contribute to increased night sky brightness. When corrected for the effects of direct illumination from high buildings, we found that the night sky brightness in the central business district (CBD) is very close to that expected for a city of Perth's population from modelling work and observations obtained in earlier studies. Given that our night sky brightness measurements in Perth over 2009 and 2010 are commensurate with that measured in Canadian cities over 30 years earlier implies that the various lighting systems employed in Perth (and probably most other cities) have not been optimised to minimize light pollution over that time. We also found that night sky brightness diminished with distance with an exponent of approximately -0.25 ± 0.02 from 3.5 to 10 km from the Perth CBD, a region characterized by urban and commercial land use. For distances

Mechanical design and fabrication of the VHF-gun, the Berkeley normal-conducting continuous-wave high-brightness electron source

Science.gov (United States)

Wells, R. P.; Ghiorso, W.; Staples, J.; Huang, T. M.; Sannibale, F.; Kramasz, T. D.

2016-02-01

A high repetition rate, MHz-class, high-brightness electron source is a key element in future high-repetition-rate x-ray free electron laser-based light sources. The VHF-gun, a novel low frequency radio-frequency gun, is the Lawrence Berkeley National Laboratory (LBNL) response to that need. The gun design is based on a normal conducting, single cell cavity resonating at 186 MHz in the VHF band and capable of continuous wave operation while still delivering the high accelerating fields at the cathode required for the high brightness performance. The VHF-gun was fabricated and successfully commissioned in the framework of the Advanced Photo-injector EXperiment, an injector built at LBNL to demonstrate the capability of the gun to deliver the required beam quality. The basis for the selection of the VHF-gun technology, novel design features, and fabrication techniques are described.

First results from the high-brightness x-ray spectroscopy beamline at ALS

Energy Technology Data Exchange (ETDEWEB)

Perera, R.C.C.; Ng, W.; Jones, G. [Lawrence Berkeley National Lab., CA (United States)] [and others

1997-04-01

Beamline 9.3.1 at the Advanced Light Source (ALS) is a windowless beamline, covering the 1-6 keV photon-energy range, designed to achieve the goal of high brightness at the sample for use in the X-ray Atomic and Molecular Spectroscopy (XAMS) science, surface and interface science, biology and x-ray optical development programs at ALS. X-ray absorption and time of flight photo emission measurements in 2 - 5 keV photon energy in argon along with the flux, resolution, spot size and stability of the beamline will be discussed. Prospects for future XAMS measurements will also be presented.

Development of a high brightness, high current SRF photo-electron source for ERL applications

Energy Technology Data Exchange (ETDEWEB)

Neumann, Axel [Helmholtz-Zentrum Berlin (Germany); Collaboration: bERLinPro Team

2016-07-01

Energy recovery linacs (ERL) offer the potential to combine major beam properties of the two main domains of particle accelerators: The low emittance of linear accelerators and the high average beam current of storage rings, while also allowing to compress to short bunches below the ps regime. This makes among other applications ERLs an ideal candidate for future light sources. The beam properties of the ERL are given by the performance of the injection section and hence of the beam source. Helmholtz-Zentrum Berlin is currently designing and building a high average current all superconducting CW driven ERL as a prototype to demonstrate low normalized beam emittance of 1 mm*mrad at 100 mA and short pulses of about 2 ps. In this contribution we discuss the development of this class of a high brightness, high current SRF photo-electron source and present recent commissioning results. Also, alternative approaches at other laboratories are shortly reviewed.

Effect of a single 3-hour exposure to bright light on core body temperature and sleep in humans.

Science.gov (United States)

Dijk, D J; Cajochen, C; Borbély, A A

1991-01-02

Seven human subjects were exposed to bright light (BL, approx. 2500 lux) and dim light (DL, approx. 6 lux) during 3 h prior to nocturnal sleep, in a cross-over design. At the end of the BL exposure period core body temperature was significantly higher than at the end of the DL exposure period. The difference in core body temperature persisted during the first 4 h of sleep. The latency to sleep onset was increased after BL exposure. Rapid-eye movement sleep (REMS) and slow-wave sleep (SWS; stage 3 + 4 of non-REMS) were not significantly changed. Eight subjects were exposed to BL from 20.30 to 23.30 h while their eyes were covered or uncovered. During BL exposure with uncovered eyes, core body temperature decreased significantly less than during exposure with covered eyes. We conclude that bright light immediately affects core body temperature and that this effect is mediated via the eyes.

Zero- and two-dimensional hybrid carbon phosphors for high colorimetric purity white light-emission.

Science.gov (United States)

Ding, Yamei; Chang, Qing; Xiu, Fei; Chen, Yingying; Liu, Zhengdong; Ban, Chaoyi; Cheng, Shuai; Liu, Juqing; Huang, Wei

2018-03-01

Carbon nanomaterials are promising phosphors for white light emission. A facile single-step synthesis method has been developed to prepare zero- and two-dimensional hybrid carbon phosphors for the first time. Zero-dimensional carbon dots (C-dots) emit bright blue luminescence under 365 nm UV light and two-dimensional nanoplates improve the dispersity and film forming ability of C-dots. As a proof-of-concept application, the as-prepared hybrid carbon phosphors emit bright white luminescence in the solid state, and the phosphor-coated blue LEDs exhibit high colorimetric purity white light-emission with a color coordinate of (0.3308, 0.3312), potentially enabling the successful application of white emitting phosphors in the LED field.

The Eindhoven High-Brightness Electron Programme

NARCIS (Netherlands)

Brussaard, G.J.H.; Wiel, van der M.J.

2004-01-01

The Eindhoven High-Brightness programme is aimed at producing ultra-short intense electron bunches from compact accelerators. The RF electron gun is capable of producing 100 fs electron bunches at 7.5 MeV and 10 pC bunch charge. The DC/RF hybrid gun under development will produce bunches <75 fs at

Low Cost Lithography Tool for High Brightness LED Manufacturing

Energy Technology Data Exchange (ETDEWEB)

Andrew Hawryluk; Emily True

2012-06-30

The objective of this activity was to address the need for improved manufacturing tools for LEDs. Improvements include lower cost (both capital equipment cost reductions and cost-ofownership reductions), better automation and better yields. To meet the DOE objective of $1- 2/kilolumen, it will be necessary to develop these highly automated manufacturing tools. Lithography is used extensively in the fabrication of high-brightness LEDs, but the tools used to date are not scalable to high-volume manufacturing. This activity addressed the LED lithography process. During R&D and low volume manufacturing, most LED companies use contact-printers. However, several industries have shown that these printers are incompatible with high volume manufacturing and the LED industry needs to evolve to projection steppers. The need for projection lithography tools for LED manufacturing is identified in the Solid State Lighting Manufacturing Roadmap Draft, June 2009. The Roadmap states that Projection tools are needed by 2011. This work will modify a stepper, originally designed for semiconductor manufacturing, for use in LED manufacturing. This work addresses improvements to yield, material handling, automation and throughput for LED manufacturing while reducing the capital equipment cost.

Lamp spectrum and spatial brightness at photopic levels

DEFF Research Database (Denmark)

Fotios, Steve; Atli, Deniz; Cheal, Chris

2015-01-01

Light sources are available in a variety of spectral power distributions (SPDs) and this affects spatial brightness in a manner not predicted by quantities such as illuminance. Tuning light source SPD to better match the sensitivity of visual perception may allow the same spatial brightness but a...

Bright to dim oscillatory response of the Neurospora circadian oscillator.

Science.gov (United States)

Gooch, Van D; Johnson, Alicia E; Larrondo, Luis F; Loros, Jennifer J; Dunlap, Jay C

2014-02-01

The fungus Neurospora crassa constitutes an important model system extensively used in chronobiology. Several studies have addressed how environmental cues, such as light, can reset or synchronize a circadian system. By means of an optimized firefly luciferase reporter gene and a controllable lighting system, we show that Neurospora can display molecular circadian rhythms in dim light when cultures receive bright light prior to entering dim light conditions. We refer to this behavior as the "bright to dim oscillatory response" (BDOR). The bright light treatment can be applied up to 76 h prior to dim exposure, and it can be as short as 15 min in duration. We have characterized this response in respect to the duration of the light pulse, the time of the light pulse before dim, the intensity of dim light, and the oscillation dynamics in dim light. Although the molecular mechanism that drives the BDOR remains obscure, these findings suggest that a long-term memory of bright light exists as part of the circadian molecular components. It is important to consider the ecological significance of such dim light responses in respect to how organisms naturally maintain their timing mechanism in moonlight.

Design of high-brightness TEM00-mode solar-pumped laser for renewable material processing

Science.gov (United States)

Liang, D.; Almeida, J.

2014-08-01

The conversion of sunlight into laser light by direct solar pumping is of ever-increasing importance because broadband, temporally constant, sunlight is converted into laser light, which can be a source of narrowband, collimated, rapidly pulsed, radiation with the possibility of obtaining extremely high brightness and intensity. Nonlinear processes, such as harmonic generation, might be used to obtain broad wavelength coverage, including the ultraviolet wavelengths, where the solar flux is very weak. The direct excitation of large lasers by sunlight offers the prospect of a drastic reduction in the cost of coherent optical radiation for high average power materials processing. This renewable laser has a large potential for many applications such as high-temperature materials processing, renewable magnesium-hydrogen energy cycle and so on. We propose here a scalable TEM00 mode solar laser pumping scheme, which is composed of four firststage 1.13 m diameter Fresnel lenses with its respective folding mirrors mounted on a two-axis automatic solar tracker. Concentrated solar power at the four focal spots of these Fresnel lenses are focused individually along a common 3.5 mm diameter, 70 mm length Nd:YAG rod via four pairs of second-stage fused-silica spherical lenses and third-stage 2D-CPCs (Compound Parabolic Concentrator), sitting just above the laser rod which is also double-pass pumped by four V-shaped pumping cavities. Distilled water cools both the rod and the concentrators. 15.4 W TEM00 solar laser power is numerically calculated, corresponding to 6.7 times enhancement in laser beam brightness.

Numerical simulations of novel high-power high-brightness diode laser structures

Science.gov (United States)

Boucke, Konstantin; Rogg, Joseph; Kelemen, Marc T.; Poprawe, Reinhart; Weimann, Guenter

2001-07-01

One of the key topics in today's semiconductor laser development activities is to increase the brightness of high-power diode lasers. Although structures showing an increased brightness have been developed specific draw-backs of these structures lead to a still strong demand for investigation of alternative concepts. Especially for the investigation of basically novel structures easy-to-use and fast simulation tools are essential to avoid unnecessary, cost and time consuming experiments. A diode laser simulation tool based on finite difference representations of the Helmholtz equation in 'wide-angle' approximation and the carrier diffusion equation has been developed. An optimized numerical algorithm leads to short execution times of a few seconds per resonator round-trip on a standard PC. After each round-trip characteristics like optical output power, beam profile and beam parameters are calculated. A graphical user interface allows online monitoring of the simulation results. The simulation tool is used to investigate a novel high-power, high-brightness diode laser structure, the so-called 'Z-Structure'. In this structure an increased brightness is achieved by reducing the divergency angle of the beam by angular filtering: The round trip path of the beam is two times folded using internal total reflection at surfaces defined by a small index step in the semiconductor material, forming a stretched 'Z'. The sharp decrease of the reflectivity for angles of incidence above the angle of total reflection leads to a narrowing of the angular spectrum of the beam. The simulations of the 'Z-Structure' indicate an increase of the beam quality by a factor of five to ten compared to standard broad-area lasers.

Much Ado about Microbunching: Coherent Bunching in High Brightness Electron Beams

Energy Technology Data Exchange (ETDEWEB)

Ratner, Daniel [Stanford Univ., CA (United States)

2011-05-01

The push to provide ever brighter coherent radiation sources has led to the creation of correspondingly bright electron beams. With billions of electrons packed into normalized emittances (phase space) below one micron, collective effects may dominate both the preservation and use of such ultra-bright beams. An important class of collective effects is due to density modulations within the bunch, or microbunching. Microbunching may be deleterious, as in the case of the Microbunching Instability (MBI), or it may drive radiation sources of unprecedented intensity, as in the case of Free Electron Lasers (FELs). In this work we begin by describing models of microbunching due to inherent beam shot noise, which sparks both the MBI as well as SLAC's Linac Coherent Light Source, the world's first hard X-ray laser. We first use this model to propose a mechanism for reducing the inherent beam shot noise as well as for predicting MBI effects. We then describe experimental measurements of the resulting microbunching at LCLS, including optical radiation from the MBI, as well as the first gain length and harmonic measurements from a hard X-ray FEL. In the final chapters, we describe schemes that use external laser modulations to microbunch light sources of the future. In these sections we describe coherent light source schemes for both both linacs and storage rings.

High brightness electron accelerator

International Nuclear Information System (INIS)

Sheffield, R.L.; Carlsten, B.E.; Young, L.M.

1994-01-01

A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of accelerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electrons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electrons as the electrons enter the first cavity. 5 figs

A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

Science.gov (United States)

Nijboer, Tanja C W; Nys, Gudrun M S; van der Smagt, Maarten J; de Haan, Edward H F

2009-01-01

We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level sensory impairments. The patient was not able to indicate the darker or the lighter of two grey squares, even though she was able to see that they differed. In addition, she could not indicate whether the lights in a room were switched on or off, nor was she able to differentiate between normal greyscale images and inverted greyscale images. As the patient recognised objects, colours, and shapes correctly, the impairment is specific for brightness. As low-level, sensory processing is normal, this specific deficit in the recognition and appreciation of brightness appears to be of a higher, cognitive level, the level of semantic knowledge. This appears to be the first report of 'brightness agnosia'.

Proceedings of the third ICFA mini-workshop on high intensity, high brightness hadron accelerators

International Nuclear Information System (INIS)

Roser, T.

1997-01-01

The third mini-workshop on high intensity, high brightness hadron accelerators was held at Brookhaven National Laboratory on May 7-9, 1997 and had about 30 participants. The workshop focussed on rf and longitudinal dynamics issues relevant to intense and/or bright hadron synchrotrons. A plenary session was followed by four sessions on particular topics. This document contains copies of the viewgraphs used as well as summaries written by the session chairs

Discussion of high brightness rf linear accelerators

International Nuclear Information System (INIS)

Jameson, R.A.

1987-01-01

The fundamental aspects of high-brightness rf linacs are outlined, showing the breadth and complexity of the technology and indicating that synergism with advancements in other areas is important. Areas of technology reviewed include ion sources, injectors, rf accelerator structures, beam dynamics, rf power, and automatic control

Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism.

Science.gov (United States)

Fan, Tingting; Grychtol, Patrik; Knut, Ronny; Hernández-García, Carlos; Hickstein, Daniel D; Zusin, Dmitriy; Gentry, Christian; Dollar, Franklin J; Mancuso, Christopher A; Hogle, Craig W; Kfir, Ofer; Legut, Dominik; Carva, Karel; Ellis, Jennifer L; Dorney, Kevin M; Chen, Cong; Shpyrko, Oleg G; Fullerton, Eric E; Cohen, Oren; Oppeneer, Peter M; Milošević, Dejan B; Becker, Andreas; Jaroń-Becker, Agnieszka A; Popmintchev, Tenio; Murnane, Margaret M; Kapteyn, Henry C

2015-11-17

We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

Intranasal administration of dopamine attenuates unconditioned fear in that it reduces restraint-induced ultrasound vocalizations and escape from bright light.

Science.gov (United States)

Talbot, Teddy; Mattern, Claudia; de Souza Silva, Maria Angelica; Brandão, Marcus Lira

2017-06-01

Although substantial evidence suggests that dopamine (DA) enhances conditioned fear responses, few studies have examined the role of DA in unconditioned fear states. Whereas DA does not cross the blood-brain barrier, intranasally-applied dopamine reaches the brain directly via the nose-brain pathways in rodents, providing an alternative means of targeting DA receptors. Intranasal dopamine (IN-DA) has been demonstrated to bind to DA transporters and to increase extracellular DA in the striatum as well as having memory-promoting effects in rats. The purpose of this study was to examine the influence of IN-DA in three tests of fear/anxiety. The three doses of DA hydrochloride (0.03, 0.3, or 1 mg/kg) were applied in a viscous castor oil gel in a volume of 5 µl to each of both nostrils of adult Wistar rats prior to testing of (a) escape from a bright light, using a two-chamber procedure, (b) restraint-induced 22 kHz ultrasound vocalizations (USVs), and (c) exploratory behavior in the elevated plus-maze (EPM). IN-DA dose-dependently reduced escape from bright light and the number of USV responses to restraint. It had no influence on the exploratory behavior in the EPM. IN-DA application reduced escape behavior in two tests of unconditioned fear (escape from bright light and USV response to immobilization). These findings may be interpreted in light of the known antidepressant action of IN-DA and DA reuptake blockers. The results also confirm the promise of the nasal route as an alternative means for targeting the brain's dopaminergic receptors with DA.

Strain relief InGaN/GaN MQW micro-pillars for high brightness LEDs

KAUST Repository

Shen, Chao

2013-01-01

Micro-structured group-III-nitrides are considered as promising strain relief structures for high efficiency solid state lighting. In this work, the strain field in InGaN/GaN multi-quantum wells (MQWs) micro-pillars is investigated using micro-Raman spectroscopy and the design of micro-pillars were studied experimentally. We distinguished the strained and strain-relieved signatures of the GaN layer from the E2 phonon peak split from the Raman scattering signatures at 572 cm-1 and 568 cm-1, respectively. The extent of strain relief is examined considering the height and size of micro-pillars fabricated using focused ion beam (FIB) micro-machining technique. A significant strain relief can be achieved when one micro-machined through the entire epi-layers, 3 μm in our study. The dependence of strain relief on micro-pillar diameter (D) suggested that micro-pillar with D < 3 μm showed high degree of strain relief. Our results shed new insights into designing strain-relieved InGaN/GaN microstructures for high brightness light emitting diode arrays. © 2013 IEEE.

Highly Efficient Spectrally Stable Red Perovskite Light-Emitting Diodes.

Science.gov (United States)

Tian, Yu; Zhou, Chenkun; Worku, Michael; Wang, Xi; Ling, Yichuan; Gao, Hanwei; Zhou, Yan; Miao, Yu; Guan, Jingjiao; Ma, Biwu

2018-05-01

Perovskite light-emitting diodes (LEDs) have recently attracted great research interest for their narrow emissions and solution processability. Remarkable progress has been achieved in green perovskite LEDs in recent years, but not blue or red ones. Here, highly efficient and spectrally stable red perovskite LEDs with quasi-2D perovskite/poly(ethylene oxide) (PEO) composite thin films as the light-emitting layer are reported. By controlling the molar ratios of organic salt (benzylammonium iodide) to inorganic salts (cesium iodide and lead iodide), luminescent quasi-2D perovskite thin films are obtained with tunable emission colors from red to deep red. The perovskite/polymer composite approach enables quasi-2D perovskite/PEO composite thin films to possess much higher photoluminescence quantum efficiencies and smoothness than their neat quasi-2D perovskite counterparts. Electrically driven LEDs with emissions peaked at 638, 664, 680, and 690 nm have been fabricated to exhibit high brightness and external quantum efficiencies (EQEs). For instance, the perovskite LED with an emission peaked at 680 nm exhibits a brightness of 1392 cd m -2 and an EQE of 6.23%. Moreover, exceptional electroluminescence spectral stability under continuous device operation has been achieved for these red perovskite LEDs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fluorescence brightness and photostability of individual copper (I) oxide nanocubes.

Science.gov (United States)

Zohora, Nafisa; Kandjani, Ahmad Esmaielzadeh; Orth, Antony; Brown, Hannah M; Hutchinson, Mark R; Gibson, Brant C

2017-12-04

Conventional organic fluorophores lose their ability to fluoresce after repeated exposure to excitation light due to photobleaching. Therefore, research into emerging bright and photostable nanomaterials has become of great interest for a range of applications such as bio-imaging and tracking. Among these emerging fluorophores, metal oxide-based nanomaterials have attracted significant attention as a potential multifunctional material with photocatalytic and angeogenisis abilities in addition to fluorescnce applications. However, most of these applications are highly dependent on size, morphology, and chemo-physical properties of individual particles. In this manuscript, we present a method to study the intrinsic optical characteristics of individual copper (I) oxide (Cu 2 O) nanocubes. When excited at 520 nm using only 11 µW excitation power (1.7 W/cm2), individual nanocubes were observed to emit light with peak wavelengths ~760 nm which is conveniently within the near-infrared 1 (NIR1) biological window where tissue autofluorescence is minimal. Bright and photostable fluorescence was observed with intensities up to 487 K counts/s under constant illumination for at least 2 minutes with a brightness approximately four times higher than the autofluorescence from a fixed cumulus-oocyte complex. With near-IR emission, high fluorescence brightness, and outstanding photostability, Cu 2 O nanocubes are attractive candidates for long-term fluorescent bioimaging applications.

Driving home from the night shift: a bright light intervention study.

Science.gov (United States)

Weisgerber, Denise M; Nikol, Maria; Mistlberger, Ralph E

2017-02-01

Sleep deprivation (SD) impairs vigilance and increases the risk of driving accidents during the commute home after night work. Bright light (BL) can enhance alertness and cognitive performance. We examined the effects of BL (5600 lux) versus dim light (DL, 35 lux) at the end of a night awake on driving performance. Subjects (N = 19, 22.8 ± 4 ya) completed three conditions, counterbalanced for order at >1 week intervals. The two overnight SD conditions began in the lab at usual bedtime. After six hours in DL, subjects were exposed to 45 min BL or continued DL, and then completed a 44 min driving test (two lap circuit) in a high fidelity simulator. In the rested condition, subjects slept at home until habitual wakeup time, were transported to the lab and ∼45 min after wakeup, received BL and then the driving test. Oral temperature decreased while reaction time and sleepiness increased across both SD nights. BL suppressed salivary melatonin but had little or no effect on sleepiness or reaction time. SD markedly increased incidents and accidents. Five subjects (26%) sustained a terminal accident (eg, car flip) in the SD-DL condition, but none did so in the SD-BL or rested-BL conditions. Compared to SD-DL, SD-BL was associated with fewer incidents and accidents overall, and with better performance on the second lap of the circuit on several performance measures. BL at the end of a night shift may have potential as a countermeasure to improve driving following night work. Copyright © 2016 Elsevier B.V. All rights reserved.

NIGHT SKY BRIGHTNESS ABOVE ZAGREB 2012.-2017.

Directory of Open Access Journals (Sweden)

Željko Andreić

2018-01-01

Full Text Available The night sky brightness at the RGN site (near the centre of Zagreb, Croatia was monitored form January 2012. to December 2017. The gathered data show that the average night sky brightness in this period did not change significantly, apart from differences caused by yearly variations in meteorological parameters. The nightly minima, maxima and mean values of the sky brightness do change considerably due to changes in meteorological conditions, often being between 2 and 3 magnitudes. The seasonal probability curves and histograms are constructed and are used to obtain additional information on the light pollution at the RGN site. They reveal that the night sky brightness clutters around two peaks, at about 15.0 mag/arcsec2 and at about 18.2 mag/arcsec2. The tendency to slightly lower brightness values in spring and summer can also be seen in the data. Two peaks correspond to cloudy and clear nights respectively, the difference in brightness between them being about 3 magnitudes. A crude clear/cloudy criterion can be defined too: the minimum between two peaks is around 16.7 mag/arcsec2. The brightness values smaller than thisare attributed to clear nights and vice-versa. Comparison with Vienna and Hong-Kong indicates that the light pollution of Zagreb is a few times larger.

Generation of Bright, Spatially Coherent Soft X-Ray High Harmonics in a Hollow Waveguide Using Two-Color Synthesized Laser Pulses.

Science.gov (United States)

Jin, Cheng; Stein, Gregory J; Hong, Kyung-Han; Lin, C D

2015-07-24

We investigate the efficient generation of low-divergence high-order harmonics driven by waveform-optimized laser pulses in a gas-filled hollow waveguide. The drive waveform is obtained by synthesizing two-color laser pulses, optimized such that highest harmonic yields are emitted from each atom. Optimization of the gas pressure and waveguide configuration has enabled us to produce bright and spatially coherent harmonics extending from the extreme ultraviolet to soft x rays. Our study on the interplay among waveguide mode, atomic dispersion, and plasma effect uncovers how dynamic phase matching is accomplished and how an optimized waveform is maintained when optimal waveguide parameters (radius and length) and gas pressure are identified. Our analysis should help laboratory development in the generation of high-flux bright coherent soft x rays as tabletop light sources for applications.

The High Luminosity Challenge: potential and limitations of High Intensity High Brightness in the LHC and its injectors

CERN Document Server

De Maria, R; Banfi, D; Barranco, J; Bartosik, H; Benedetto, E; Bruce, R; Brüning, O; Calaga, R; Cerutti, F; Damerau, H; Esposito, L; Fartoukh, S; Fitterer, M; Garoby, R; Gilardoni, S; Giovannozzi, M; Goddard, B; Gorini, B; Hanke, K; Iadarola, G; Lamont, M; Meddahi, M; Métral, E; Mikulec, B; Mounet, N; Papaphilippou, Y; Pieloni, T; Redaelli, S; Rossi, L; Rumolo, G; Shaposhnikova, E; Sterbini, G; Todesco, E; Tomás, R; Zimmermann, F; Valishev, A

2014-01-01

High-intensity and high-brightness beams are key ingredients to maximize the LHC integrated luminosity and to exploit its full potential. This contribution describes the optimization of beam and machine parameters to maximize the integrated luminosity as seen by the LHC experiments, by taking into account the expected intensity and brightness reach of LHC itself and its injector chain as well as the capabilities of the detectors for next run and foreseen upgrade scenarios.

Characterizing the Motion of Solar Magnetic Bright Points at High Resolution

Science.gov (United States)

Van Kooten, Samuel J.; Cranmer, Steven R.

2017-11-01

Magnetic bright points in the solar photosphere, visible in both continuum and G-band images, indicate footpoints of kilogauss magnetic flux tubes extending to the corona. The power spectrum of bright-point motion is thus also the power spectrum of Alfvén wave excitation, transporting energy up flux tubes into the corona. This spectrum is a key input in coronal and heliospheric models. We produce a power spectrum of bright-point motion using radiative magnetohydrodynamic simulations, exploiting spatial resolution higher than can be obtained in present-day observations, while using automated tracking to produce large data quantities. We find slightly higher amounts of power at all frequencies compared to observation-based spectra, while confirming the spectrum shape of recent observations. This also provides a prediction for observations of bright points with DKIST, which will achieve similar resolution and high sensitivity. We also find a granule size distribution in support of an observed two-population distribution, and we present results from tracking passive tracers, which show a similar power spectrum to that of bright points. Finally, we introduce a simplified, laminar model of granulation, with which we explore the roles of turbulence and of the properties of the granulation pattern in determining bright-point motion.

Quadrature measurements of a bright squeezed state via sideband swapping

DEFF Research Database (Denmark)

Schneider, J.; Glockl, O.; Leuchs, G.

2009-01-01

The measurement of an arbitrary quadrature of a bright quantum state of light is a commonly requested action in many quantum information protocols, but it is experimentally challenging with previously proposed schemes. We suggest that the quadrature be measured at a specific sideband frequency...... of a bright quantum state by transferring the sideband modes under interrogation to a vacuum state and subsequently measuring the quadrature via homodyne detection. The scheme is implemented experimentally, and it is successfully tested with a bright squeezed state of light....

Robust brightness enhancement across a luminance range of the glare illusion.

Science.gov (United States)

Tamura, Hideki; Nakauchi, Shigeki; Koida, Kowa

2016-01-01

The glare illusion refers to brightness enhancement and the perception of a self-luminous appearance that occurs when a central region is surrounded by a luminance gradient. The center region appears to be a light source, with its light dispersing into the surrounding region. If the luminous edge is critical for generating the illusion, modulating the perceived luminance of the image, and switching its appearance from luminous to nonluminous, would have a strong impact on lightness and brightness estimation. Here, we quantified the illusion in two ways, by assessing brightness enhancement and examining whether the center region appeared luminous. Thus, we could determine whether the two effects occurred jointly or independently. We examined a wide luminance range of center regions, from 0 to 200% relative to background. Brightness enhancement in the illusion was observed for a wide range of luminances (20% to 200% relative to background), while a luminous-white appearance was observed when the center region luminance was 145% of the background. These results exclude the possibility that brightness enhancement occurs because the stimuli appear self-luminous. We suggest that restoring the original image intensity precedes the perceptual process of lightness estimation.

Initial observations of high-charge, low-emittance electron beams at HIBAF (High Brightness Accelerator FEL)

Energy Technology Data Exchange (ETDEWEB)

Lumpkin, A.H.; Feldman, R.B.; Carsten, B.E.; Feldman, D.W.; Sheffield, R.L.; Stein, W.E.; Johnson, W.J.; Thode, L.E.; Bender, S.C.; Busch, G.E.

1990-01-01

We report our initial measurements of bright (high-charge, low-emittance) electron beams generated at the Los Alamos High Brightness Accelerator FEL (HIBAF) Facility. Normalized emittance values of less than 50 {pi} mm-mrad for charges ranging from 0.7 to 8.7 nC were obtained for single micropulses at a y-waist and at an energy of 14.7 MeV. These measurements were part of the commissioning campaign on the HIBAF photoelectric injector. Macropulse measurements have also been performed and are compared with PARMELA simulations. 5 refs., 8 figs., 3 tabs.

PePSS - A portable sky scanner for measuring extremely low night-sky brightness

Science.gov (United States)

Kocifaj, Miroslav; Kómar, Ladislav; Kundracik, František

2018-05-01

A new portable sky scanner designed for low-light-level detection at night is developed and employed in night sky brightness measurements in a rural region. The fast readout, adjustable sensitivity and linear response guaranteed in 5-6 orders of magnitude makes the device well suited for narrow-band photometry in both dark areas and bright urban and suburban environments. Quasi-monochromatic night-sky brightness data are advantageous in the accurate characterization of spectral power distribution of scattered and emitted light and, also allows for the possibility to retrieve light output patterns from whole-city light sources. The sky scanner can operate in both night and day regimes, taking advantage of the complementarity of both radiance data types. Due to its inherent very high sensitivity the photomultiplier tube could be used in night sky radiometry, while the spectrometer-equipped system component capable of detecting elevated intensities is used in daylight monitoring. Daylight is a source of information on atmospheric optical properties that in turn are necessary in processing night sky radiances. We believe that the sky scanner has the potential to revolutionize night-sky monitoring systems.

An hour of bright white light in the early morning improves performance and advances sleep and circadian phase during the Antarctic winter.

Science.gov (United States)

Corbett, R W; Middleton, B; Arendt, J

2012-09-13

Previous work has demonstrated that exposure to an hour of bright light in the morning and the evening during the Polar winter has beneficial effects on circadian phase. This study investigated the effect of a single hour of bright white morning light on circadian phase, sleep, alertness and cognitive performance. Nine individuals (eight male, one female, median age 30 years), wintering at Halley Research Station (75°S), Antarctica from 7th May until 6th August 2007, were exposed to bright white light for a fortnight from 08:30 to 09:30 h, with two fortnight control periods on either side. This sequence was performed twice, before and following Midwinter. Light exposure, sleep and alertness were assessed daily by actigraphy, sleep diaries and subjective visual analogue scales. Circadian phase (assessed by urinary 6-sulphatoxymelatonin rhythm) and cognitive performance were evaluated at the end of each fortnight. During light exposure circadian phase was advanced from 4.97 ± 0.96 decimal hours (dh) (mean ± SD) to 4.08 ± 0.68 dh (p = 0.003). Wake-up time was shifted by a similar margin from 8.45 ± 1.83 dh to 7.59 ± 0.78 dh (p < 0.001). Sleep start time was also advanced (p = 0.047) but by a lesser amount, consequently, actual sleep time was slightly reduced. There was no change in objective or subjective measures of sleep quality or subjective measures of alertness. An improvement in cognitive performance was found with both the Single Letter Cancellation Test (p < 0.001) and the Digit Symbol Substitution Test (p = 0.026) with preserved circadian variation. These beneficial effects of a single short duration light treatment may have implications not only for the Antarctic but other remote environments where access to natural light and delayed circadian phase, is problematic. These results require validation in larger studies at varying locations. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Manakins can produce iridescent and bright feather colours without melanosomes.

Science.gov (United States)

Igic, Branislav; D'Alba, Liliana; Shawkey, Matthew D

2016-06-15

Males of many species often use colourful and conspicuous ornaments to attract females. Among these, male manakins (family: Pipridae) provide classic examples of sexual selection favouring the evolution of bright and colourful plumage coloration. The highly iridescent feather colours of birds are most commonly produced by the periodic arrangement of melanin-containing organelles (melanosomes) within barbules. Melanin increases the saturation of iridescent colours seen from optimal viewing angles by absorbing back-scattered light; however, this may reduce the wide-angle brightness of these signals, contributing to a dark background appearance. We examined the nanostructure of four manakin species (Lepidothrix isidorei, L. iris, L. nattereri and L. coeruleocapilla) to identify how they produce their bright plumage colours. Feather barbs of all four species were characterized by dense and fibrous internal spongy matrices that likely increase scattering of light within the barb. The iridescent, yet pale or whitish colours of L. iris and L. nattereri feathers were produced not by periodically arranged melanosomes within barbules, but by periodic matrices of air and β-keratin within barbs. Lepidothrix iris crown feathers were able to produce a dazzling display of colours with small shifts in viewing geometry, likely because of a periodic nanostructure, a flattened barb morphology and disorder at a microstructural level. We hypothesize that iridescent plumage ornaments of male L. iris and L. nattereri are under selection to increase brightness or luminance across wide viewing angles, which may potentially increase their detectability by females during dynamic and fast-paced courtship displays in dim light environments. © 2016. Published by The Company of Biologists Ltd.

Bright nanoscale source of deterministic entangled photon pairs violating Bell's inequality

NARCIS (Netherlands)

Jöns, K.D.; Schweickert, L.S.; Versteegh, M.A.M.; Dalacu, Dan; Poole, Philip J.; Gulinatti, Angelo; Giudice, Andrea; Zwiller, V.G.; Reimer, M.E.

2017-01-01

Global, secure quantum channels will require efficient distribution of entangled photons. Long distance, low-loss interconnects can only be realized using photons as quantum information carriers. However, a quantum light source combining both high qubit fidelity and on-demand bright emission has

Bright squeezed vacuum in a nonlinear interferometer: frequency/temporal Schmidt-mode description

OpenAIRE

Sharapova, P. R.; Tikhonova, O. V.; Lemieux, S.; Boyd, R. W.; Chekhova, M. V.

2018-01-01

Control over the spectral properties of the bright squeezed vacuum (BSV), a highly multimode non-classical macroscopic state of light that can be generated through high-gain parametric down conversion, is crucial for many applications. In particular, in several recent experiments BSV is generated in a strongly pumped SU(1,1) interferometer to achieve phase supersensitivity, perform broadband homodyne detection, or tailor the frequency spectrum of squeezed light. In this work, we present an an...

The surface brightness of spiral galaxies

International Nuclear Information System (INIS)

Phillipps, S.; Disney, M.

1983-01-01

It is proposed that Freeman's discovery that the extrapolated central surface brightness of spiral galaxies is approximately constant can be simply explained if the galaxies contain a spheroidal component which dominates the light in their outer isophotes. Calculations of an effective central surface brightness indicate a wide spread of values. This requires either a wide spread in disc properties or significant spheroidal components or, most probably, both. (author)

Transverse emittance-preserving arc compressor for high-brightness electron beam-based light sources and colliders

Science.gov (United States)

Di Mitri, S.; Cornacchia, M.

2015-03-01

Bunch length magnetic compression is used in high-brightness linacs driving free-electron lasers (FELs) and particle colliders to increase the peak current of the injected beam. To date, it is performed in dedicated insertions made of few degrees bending magnets and the compression factor is limited by the degradation of the beam transverse emittance owing to emission of coherent synchrotron radiation (CSR). We reformulate the known concept of CSR-driven optics balance for the general case of varying bunch length and demonstrate, through analytical and numerical results, that a 500 pC charge beam can be time-compressed in a periodic 180 deg arc at 2.4 GeV beam energy and lower, by a factor of up to 45, reaching peak currents of up to 2 kA and with a normalized emittance growth at the 0.1 μ \\text{m} rad level. The proposed solution offers new schemes of beam longitudinal gymnastics; an application to an energy recovery linac driving FEL is discussed.

Short Pulse High Brightness X-ray Production with the PLEIADES Thomson Scattering Source

International Nuclear Information System (INIS)

Anderson, S.G.; Barty, C.P.J.; Betts, S.M.; Brown, W.J.; Crane, J.K.; Cross, R.R.; Fittinghoff, D.N.; Gibson, D.J.; Hartemann, F.V.; Kuba, J.; LaSage, G.P.; Rosenzweig, J.B.; Slaughter, D.R.; Springer, P.T.; Tremaine, A.M.

2003-01-01

We describe PLEIADES, a compact, tunable, high-brightness, ultra-short pulse, Thomson x-ray source. The peak brightness of the source is expected to exceed 10 20 photons/s/0.1% bandwidth/mm 2 /mrad 2 . Initial results are reported and compared to theoretical calculations

Possible Bright Starspots on TRAPPIST-1

Science.gov (United States)

Morris, Brett M.; Agol, Eric; Davenport, James R. A.; Hawley, Suzanne L.

2018-04-01

The M8V star TRAPPIST-1 hosts seven roughly Earth-sized planets and is a promising target for exoplanet characterization. Kepler/K2 Campaign 12 observations of TRAPPIST-1 in the optical show an apparent rotational modulation with a 3.3-day period, though that rotational signal is not readily detected in the Spitzer light curve at 4.5 μm. If the rotational modulation is due to starspots, persistent dark spots can be excluded from the lack of photometric variability in the Spitzer light curve. We construct a photometric model for rotational modulation due to photospheric bright spots on TRAPPIST-1 that is consistent with both the Kepler and Spitzer light curves. The maximum-likelihood model with three spots has typical spot sizes of R spot/R ⋆ ≈ 0.004 at temperature T spot ≳ 5300 ± 200 K. We also find that large flares are observed more often when the brightest spot is facing the observer, suggesting a correlation between the position of the bright spots and flare events. In addition, these flares may occur preferentially when the spots are increasing in brightness, which suggests that the 3.3-day periodicity may not be a rotational signal, but rather a characteristic timescale of active regions.

Effects of melatonin and bright light treatment in childhood chronic sleep onset insomnia with late melatonin onset: A randomised controlled study

NARCIS (Netherlands)

van Maanen, A.; Meijer, A.M.; Smits, M.G.; van der Heijden, K.B.; Oort, F.J.

2017-01-01

STUDY OBJECTIVES: Chronic sleep onset insomnia with late melatonin onset is prevalent in childhood, and has negative daytime consequences. Melatonin treatment is known to be effective in treating these sleep problems. Bright light therapy might be an alternative treatment, with potential advantages

Transverse Laser Beam Shaping in High Brightness Electron Gun at ATF

CERN Document Server

Roychowdhury, S

2005-01-01

The brightness of electron beams from a photo injector is influenced by the transverse and longitudinal distribution of the laser beam illuminating the cathode. Previous studies at Brookhaven Accelerator Test Facility have shown that formation of an ideal e-beam with lowest transverse emittance requires uniform circular distribution of the emitted electrons. The use of the uniformly distributed power of the laser beam may not lead to that of the emitted electrons because of the non-uniform quantum efficiency. A proper shaping of the laser beam can compensate for this non-uniformity. In this paper we describe the use of digital light processing (DLP) technique based on digital mirror device (DMD) for spatial modulation of the laser beam, for measurements of the quantum efficiency map, and for creating the desirable e-beam density profiles. A DMD is aμelectronic mechanical system (MEMS) comprising of millions of highly reflectiveμmirrors controlled by underlying electronics. We present exper...

Fifty shades of white: how white feather brightness differs among species

Science.gov (United States)

Igic, Branislav; D'Alba, Liliana; Shawkey, Matthew D.

2018-04-01

White colouration is a common and important component of animal visual signalling and camouflage, but how and why it varies across species is poorly understood. White is produced by wavelength-independent and diffuse scattering of light by the internal structures of materials, where the degree of brightness is related to the amount of light scattered. Here, we investigated the morphological basis of brightness differences among unpigmented pennaceous regions of white body feathers across 61 bird species. Using phylogenetically controlled comparisons of reflectance and morphometric measurements, we show that brighter white feathers had larger and internally more complex barbs than duller white feathers. Higher brightness was also associated with more closely packed barbs and barbules, thicker and longer barbules, and rounder and less hollow barbs. Larger species tended to have brighter white feathers than smaller species because they had thicker and more complex barbs, but aquatic species were not significantly brighter than terrestrial species. As similar light scattering principals affect the brightness of chromatic signals, not just white colours, these findings help broaden our general understanding of the mechanisms that affect plumage brightness. Future studies should examine how feather layering on a bird's body contributes to differences between brightness of white plumage patches within and across species.

Green bright squeezed light from a cw periodically poled KTP second harmonic generator

DEFF Research Database (Denmark)

Andersen, Ulrik Lund; Buchhave, Preben

2002-01-01

We present the experimental observation of bright amplitude squeezed light from a singly resonant second harmonic generator (SHG) based on a periodically poled potassium titanyl phosphate (KTP) crystal. Contrary to conventional SHG, the interacting waves in this device couple efficiently using qu...... reduction is greater than what could be expected using normal birefringence phase matched KTP with the same experimental parameters. Excellent agreement between experiment and theory is found. (C)2002 Optical Society of America....... quasi phase matching (QPM) and more importantly QPM allows access to higher valued elements of the nonlinear tensor than is possible under the constraint of birefringence phase matching. We observe a noise reduction of 13% below the shot noise limit in the generated second harmonic field. This noise...

Considerations for high-brightness electron sources

International Nuclear Information System (INIS)

Jameson, R.A.

1990-01-01

Particle accelerators are now used in many areas of physics research and in industrial and medical applications. New uses are being studied to address major societal needs in energy production, materials research, generation of intense beams of radiation at optical and suboptical wavelengths, treatment of various kinds of waste, and so on. Many of these modern applications require a high intensity beam at the desired energy, along with a very good beam quality in terms of the beam confinement, aiming, or focusing. Considerations for ion and electron accelerators are often different, but there are also many commonalties, and in fact, techniques derived for one should perhaps more often be considered for the other as well. We discuss some aspects of high-brightness electron sources here from that point of view. 6 refs

Temperature dependence of Ce:YAG single-crystal phosphors for high-brightness white LEDs/LDs

Science.gov (United States)

Arjoca, Stelian; Víllora, Encarnación G.; Inomata, Daisuke; Aoki, Kazuo; Sugahara, Yoshiyuki; Shimamura, Kiyoshi

2015-05-01

The growth of Ce:Y3Al5O12(Ce:YAG) single-crystal phosphors (SCPs) by the Czochralski technique is analyzed in terms of segregation coefficient, solubility and absorption cross-section. The emission characteristics of these SCPs are investigated in a wide temperature range, from liquid He temperature up to 500 °C. The internal quantum efficiency of SCPs achieves its maximum at about 250 °C. Thermal quenching of SCPs at high temperature is attributed to the Mott-Seitz mechanism. In the case of ceramic powder phosphors, a continuous droop is observed with the temperature due to defect-related non-radiative recombination paths. It is shown that (Ce:YAG SCPs + blue LEDs/LDs) can cover a wide range of color temperatures 5500-7000 K, with color rendering indices around 70. In conclusion, it is shown that Ce:YAG SCPs are the most efficient and temperature stable converters to fabricate high-brightness white light sources with high-power blue LEDs and LDs.

Spatially single-mode source of bright squeezed vacuum

OpenAIRE

Pérez, A. M.; Iskhakov, T. Sh.; Sharapova, P.; Lemieux, S.; Tikhonova, O. V.; Chekhova, M. V.; Leuchs, G.

2014-01-01

Bright squeezed vacuum, a macroscopic nonclassical state of light, can be obtained at the output of a strongly pumped non-seeded traveling-wave optical parametric amplifier (OPA). By constructing the OPA of two consecutive crystals separated by a large distance we make the squeezed vacuum spatially single-mode without a significant decrease in the brightness or squeezing.

980 nm high brightness external cavity broad area diode laser bar

DEFF Research Database (Denmark)

Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup Nielsen, Birgitte

2009-01-01

We demonstrate of-axis spectral beam combining applied to a 980 nm high power broad area diode laser bar. The experiments yielded 9 W of optical power at 30 A of operating current and the measured M2 values of the combined beam from 12 emitters were 1.9 and 6.4 for the fast and the slow axis......, respectively. The slow axis beam quality was 5-6 times better than the value obtained from a single emitter in free running mode. A high brightness of 79 MW/cm2-str was achieved using this configuration. To our knowledge, this is the highest brightness level ever achieved from a broad area diode laser bar....

Bright triplet excitons in caesium lead halide perovskites

Science.gov (United States)

Becker, Michael A.; Vaxenburg, Roman; Nedelcu, Georgian; Sercel, Peter C.; Shabaev, Andrew; Mehl, Michael J.; Michopoulos, John G.; Lambrakos, Samuel G.; Bernstein, Noam; Lyons, John L.; Stöferle, Thilo; Mahrt, Rainer F.; Kovalenko, Maksym V.; Norris, David J.; Rainò, Gabriele; Efros, Alexander L.

2018-01-01

Nanostructured semiconductors emit light from electronic states known as excitons. For organic materials, Hund’s rules state that the lowest-energy exciton is a poorly emitting triplet state. For inorganic semiconductors, similar rules predict an analogue of this triplet state known as the ‘dark exciton’. Because dark excitons release photons slowly, hindering emission from inorganic nanostructures, materials that disobey these rules have been sought. However, despite considerable experimental and theoretical efforts, no inorganic semiconductors have been identified in which the lowest exciton is bright. Here we show that the lowest exciton in caesium lead halide perovskites (CsPbX3, with X = Cl, Br or I) involves a highly emissive triplet state. We first use an effective-mass model and group theory to demonstrate the possibility of such a state existing, which can occur when the strong spin-orbit coupling in the conduction band of a perovskite is combined with the Rashba effect. We then apply our model to CsPbX3 nanocrystals, and measure size- and composition-dependent fluorescence at the single-nanocrystal level. The bright triplet character of the lowest exciton explains the anomalous photon-emission rates of these materials, which emit about 20 and 1,000 times faster than any other semiconductor nanocrystal at room and cryogenic temperatures, respectively. The existence of this bright triplet exciton is further confirmed by analysis of the fine structure in low-temperature fluorescence spectra. For semiconductor nanocrystals, which are already used in lighting, lasers and displays, these excitons could lead to materials with brighter emission. More generally, our results provide criteria for identifying other semiconductors that exhibit bright excitons, with potential implications for optoelectronic devices.

Enhanced brightness of organic light-emitting diodes based on Mg:Ag cathode using alkali metal chlorides as an electron injection layer

International Nuclear Information System (INIS)

Zou Ye; Deng Zhenbo; Xu Denghui; Lü Zhaoyue; Yin Yuehong; Du Hailiang; Chen Zheng; Wang Yongsheng

2012-01-01

Different thicknesses of cesium chloride (CsCl) and various alkali metal chlorides were inserted into organic light-emitting diodes (OLEDs) as electron injection layers (EILs). The basic structure of OLED is indium tin oxide (ITO)/N,N′-diphenyl-N,N′-bis(1-napthyl-phenyl)-1.1′-biphenyl-4.4′-diamine (NPB)/tris-(8-hydroxyquinoline) aluminum (Alq 3 )/Mg:Ag/Ag. The electroluminescent (EL) performance curves show that both the brightness and efficiency of the OLEDs can be obviously enhanced by using a thin alkali metal chloride layer as an EIL. The electron injection barrier height between the Alq 3 layer and Mg:Ag cathode is reduced by inserting a thin alkali metal chloride as an EIL, which results in enhanced electron injection and electron current. Therefore, a better balance of hole and electron currents at the emissive interface is achieved and consequently the brightness and efficiency of OLEDs are improved. - Highlights: ► Alkaline metal chlorides were used as electron injection layers in organic light-emitting diodes based on Mg:Ag cathode. ► Brightness and efficiency of OLEDs with alkaline metal chlorides as electron injection layers were all greatly enhanced. ► The Improved OLED performance was attributed to the possible interfacial chemical reaction. ► Electron-only devices are fabricated to demonstrate the electron injection enhancement.

OSCILLATING LIGHT WALL ABOVE A SUNSPOT LIGHT BRIDGE

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuhong; Zhang, Jun; Jiang, Fayu [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Xiang, Yongyuan, E-mail: shuhongyang@nao.cas.cn [Fuxian Solar Observatory, Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China)

2015-05-10

With the high tempo-spatial Interface Region Imaging Spectrograph 1330 Å images, we find that many bright structures are rooted in the light bridge of NOAA 12192, forming a light wall. The light wall is brighter than the surrounding areas, and the wall top is much brighter than the wall body. The New Vacuum Solar Telescope Hα and the Solar Dynamics Observatory 171 and 131 Å images are also used to study the light-wall properties. In 1330, 171, and 131 Å, the top of the wall has a higher emission, while in the Hα line, the wall-top emission is very low. The wall body corresponds to bright areas in 1330 Å and dark areas in the other lines. The top of the light wall moves upward and downward successively, performing oscillations in height. The deprojected mean height, amplitude, oscillation velocity, and the dominant period are determined to be 3.6 Mm, 0.9 Mm, 15.4 km s{sup −1}, and 3.9 minutes, respectively. We interpret the oscillations of the light wall as the leakage of p-modes from below the photosphere. The constant brightness enhancement of the wall top implies the existence of some kind of atmospheric heating, e.g., via the persistent small-scale reconnection or the magneto-acoustic waves. In another series of 1330 Å images, we find that the wall top in the upward motion phase is significantly brighter than in the downward phase. This kind of oscillation may be powered by the energy released due to intermittent impulsive magnetic reconnection.

1.9 W yellow, CW, high-brightness light from a high efficiency semiconductor laser-based system

Science.gov (United States)

Hansen, A. K.; Christensen, M.; Noordegraaf, D.; Heist, P.; Papastathopoulos, E.; Loyo-Maldonado, V.; Jensen, O. B.; Stock, M. L.; Skovgaard, P. M. W.

2017-02-01

Semiconductor lasers are ideal sources for efficient electrical-to-optical power conversion and for many applications where their small size and potential for low cost are required to meet market demands. Yellow lasers find use in a variety of bio-related applications, such as photocoagulation, imaging, flow cytometry, and cancer treatment. However, direct generation of yellow light from semiconductors with sufficient beam quality and power has so far eluded researchers. Meanwhile, tapered semiconductor lasers at near-infrared wavelengths have recently become able to provide neardiffraction- limited, single frequency operation with output powers up to 8 W near 1120 nm. We present a 1.9 W single frequency laser system at 562 nm, based on single pass cascaded frequency doubling of such a tapered laser diode. The laser diode is a monolithic device consisting of two sections: a ridge waveguide with a distributed Bragg reflector, and a tapered amplifier. Using single-pass cascaded frequency doubling in two periodically poled lithium niobate crystals, 1.93 W of diffraction-limited light at 562 nm is generated from 5.8 W continuous-wave infrared light. When turned on from cold, the laser system reaches full power in just 60 seconds. An advantage of using a single pass configuration, rather than an external cavity configuration, is increased stability towards external perturbations. For example, stability to fluctuating case temperature over a 30 K temperature span has been demonstrated. The combination of high stability, compactness and watt-level power range means this technology is of great interest for a wide range of biological and biomedical applications.

Evaluations of the new LiF-scintillator and optional brightness enhancement films for neutron imaging

Energy Technology Data Exchange (ETDEWEB)

Iikura, H., E-mail: Iikura.hiroshi@jaea.go.jp [Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki (Japan); Tsutsui, N. [Chichibu Fuji Co., Ltd., Ogano, Chichibu, Saitama 368-0193 (Japan); Nakamura, T.; Katagiri, M.; Kureta, M. [Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki (Japan); Kubo, J. [Nissan Motor Co., Ltd., Atsugi, Kanagawa 243-0126 (Japan); Matsubayashi, M. [Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki (Japan)

2011-09-21

Japan Atomic Energy Agency has developed the neutron scintillator jointly with Chichibu Fuji Co., Ltd. In this study, we evaluated the new ZnS(Ag):Al/{sup 6}Li scintillator developed for neutron imaging. It was confirmed that the brightness increased by about double while maintaining equal performance for the spatial resolution as compared with a conventional scintillator. High frame-rate imaging using a high-speed video camera system and this new scintillator made it possible to image beyond 10 000 frames per second while still having enough brightness. This technique allowed us to obtain a high-frame-rate visualization of oil flow in a running car engine. Furthermore, we devised a technique to increase the light intensity of reception for a camera by adding brightness enhancement films on the output surface of the scintillator. It was confirmed that the spatial resolution degraded more than double, but the brightness increased by about three times.

Detection of stably bright squeezed light with the quantum noise reduction of 12.6  dB by mutually compensating the phase fluctuations.

Science.gov (United States)

Yang, Wenhai; Shi, Shaoping; Wang, Yajun; Ma, Weiguang; Zheng, Yaohui; Peng, Kunchi

2017-11-01

We present a mutual compensation scheme of three phase fluctuations, originating from the residual amplitude modulation (RAM) in the phase modulation process, in the bright squeezed light generation system. The influence of the RAM on each locking loop is harmonized by using one electro-optic modulator (EOM), and the direction of the phase fluctuation is manipulated by positioning the photodetector (PD) that extracts the error signal before or after the optical parametric amplifier (OPA). Therefore a bright squeezed light with non-classical noise reduction of π is obtained. By fitting the squeezing and antisqueezing measurement results, we confirm that the total phase fluctuation of the system is around 3.1 mrad. The fluctuation of the noise suppression is 0.2 dB for 3 h.

High brightness photonic band crystal semiconductor lasers in the passive mode locking regime

International Nuclear Information System (INIS)

Rosales, R.; Kalosha, V. P.; Miah, M. J.; Bimberg, D.; Posilović, K.; Pohl, J.; Weyers, M.

2014-01-01

High brightness photonic band crystal lasers in the passive mode locking regime are presented. Optical pulses with peak power of 3 W and peak brightness of about 180 MW cm −2  sr −1 are obtained on a 5 GHz device exhibiting 15 ps pulses and a very low beam divergence in both the vertical and horizontal directions.

Compact light-emitting diode lighting ring for video-assisted thoracic surgery.

Science.gov (United States)

Lu, Ming-Kuan; Chang, Feng-Chen; Wang, Wen-Zhe; Hsieh, Chih-Cheng; Kao, Fu-Jen

2014-01-01

In this work, a foldable ring-shaped light-emitting diode (LED) lighting assembly, designed to attach to a rubber wound retractor, is realized and tested through porcine animal experiments. Enabled by the small size and the high efficiency of LED chips, the lighting assembly is compact, flexible, and disposable while providing direct and high brightness lighting for more uniform background illumination in video-assisted thoracic surgery (VATS). When compared with a conventional fiber bundle coupled light source that is usually used in laparoscopy and endoscopy, the much broader solid angle of illumination enabled by the LED assembly allows greatly improved background lighting and imaging quality in VATS.

Compact light-emitting diode lighting ring for video-assisted thoracic surgery

Science.gov (United States)

Lu, Ming-Kuan; Chang, Feng-Chen; Wang, Wen-Zhe; Hsieh, Chih-Cheng; Kao, Fu-Jen

2014-10-01

In this work, a foldable ring-shaped light-emitting diode (LED) lighting assembly, designed to attach to a rubber wound retractor, is realized and tested through porcine animal experiments. Enabled by the small size and the high efficiency of LED chips, the lighting assembly is compact, flexible, and disposable while providing direct and high brightness lighting for more uniform background illumination in video-assisted thoracic surgery (VATS). When compared with a conventional fiber bundle coupled light source that is usually used in laparoscopy and endoscopy, the much broader solid angle of illumination enabled by the LED assembly allows greatly improved background lighting and imaging quality in VATS.

Effects of Melatonin and Bright Light Treatment in Childhood Chronic Sleep Onset Insomnia With Late Melatonin Onset: A Randomized Controlled Study.

Science.gov (United States)

van Maanen, Annette; Meijer, Anne Marie; Smits, Marcel G; van der Heijden, Kristiaan B; Oort, Frans J

2017-02-01

Chronic sleep onset insomnia with late melatonin onset is prevalent in childhood, and has negative daytime consequences. Melatonin treatment is known to be effective in treating these sleep problems. Bright light therapy might be an alternative treatment, with potential advantages over melatonin treatment. In this study, we compare the effects of melatonin and bright light treatment with a placebo condition in children with chronic sleep onset insomnia and late melatonin onset. Eighty-four children (mean age 10.0 years, 61% boys) first entered a baseline week, after which they received melatonin (N = 26), light (N = 30), or placebo pills (N = 28) for 3 to 4 weeks. Sleep was measured daily with sleep diaries and actigraphy. Before and after treatment children completed a questionnaire on chronic sleep reduction, and Dim Light Melatonin Onset (DLMO) was measured. Results were analyzed with linear mixed model analyses. Melatonin treatment and light therapy decreased sleep latency (sleep diary) and advanced sleep onset (sleep diary and actigraphy), although for sleep onset the effects of melatonin were stronger. In addition, melatonin treatment advanced DLMO and had positive effects on sleep latency and sleep efficiency (actigraphy data), and sleep time (sleep diary and actigraphy data). However, wake after sleep onset (actigraphy) increased with melatonin treatment. No effects on chronic sleep reduction were found. We found positive effects of both melatonin and light treatment on various sleep outcomes, but more and stronger effects were found for melatonin treatment. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

A randomised controlled trial of bright light therapy and morning activity for adolescents and young adults with Delayed Sleep-Wake Phase Disorder.

Science.gov (United States)

Richardson, C; Cain, N; Bartel, K; Micic, G; Maddock, B; Gradisar, M

2018-05-01

A randomised controlled trial evaluated bright light therapy and morning activity for the treatment of Delayed Sleep-Wake Phase Disorder (DSWPD) in young people. 60 adolescents and young adults (range = 13-24 years, mean = 15.9 ± 2.2 y, 63% f) diagnosed with DSWPD were randomised to receive three weeks of post-awakening Green Bright Light Therapy (∼507 nm) and Sedentary Activity (sitting, watching TV), Green Bright Light Therapy and Morning Activity (standing, playing motion-sensing videogame), Red Light Therapy (∼643 nm) and Sedentary Activity or Red Light Therapy and Morning Activity. Sleep (ie sleep onset time, wake up time, sleep onset latency, total sleep time) and daytime functioning (ie morning alertness, daytime sleepiness, fatigue, functional impairment) were measured pre-treatment, post-treatment and at one and three month follow-up. Contrary to predictions, there were no significant differences in outcomes between treatment groups; and interaction effects between treatment group and time for all outcome variables were not statistically significant. However, adolescents and young adults in morning activity conditions did not meaningfully increase their objective activity (ie movement frequency). Overall, adolescents reported significantly improved sleep timing (d = 0.30-0.46), sleep onset latency (d = 0.32) and daytime functioning (d = 0.45-0.87) post-treatment. Improvements in sleep timing (d = 0.53-0.61), sleep onset latency (d = 0.57), total sleep time (d = 0.51), and daytime functioning (d = 0.52-1.02) were maintained, or improved upon, at the three month follow-up. However, relapse of symptomology was common and 38% of adolescents and young adults requested further treatment in addition to the three weeks of light therapy. Although there is convincing evidence for the short-term efficacy of chronobiological treatments for DSWPD, long-term treatment outcomes can be improved. To address this gap in our current knowledge

High voltage high brightness electron accelerators with MITL voltage adder coupled to foilless diodes

International Nuclear Information System (INIS)

Mazarakis, M.G.; Poukey, J.W.; Frost, C.A.; Shope, S.L.; Halbleib, J.A.; Turman, B.N.

1993-01-01

During the last ten years the authors have extensively studied the physics and operation of magnetically-immersed electron foilless diodes. Most of these sources were utilized as injectors to high current, high energy linear induction accelerators such as those of the RADLAC family. Recently they have experimentally and theoretically demonstrated that foilless diodes can be successfully coupled to self-magnetically insulated transmission line voltage adders to produce very small high brightness, high definition (no halo) electron beams. The RADLAC/SMILE experience opened the path to a new approach in high brightness, high energy induction accelerators. There is no beam drifting through the device. The voltage addition occurs in a center conductor, and the beam is created at the high voltage end in an applied magnetic field diode. This work was motivated by the remarkable success of the HERMES-III accelerator and the need to produce small radius, high energy, high current electron beams for air propagation studies and flash x-ray radiography. In this paper they present experimental results compared with analytical and numerical simulations in addition to design examples of devices that can produce multikiloamp electron beams of as high as 100 MV energies and radii as small as 1 mm

Application of Cherenkov light observation to reactor measurements (1). Estimation of reactor power from Cherenkov light intensity

International Nuclear Information System (INIS)

Yamamoto, Keiichi; Takeuchi, Tomoaki; Kimura, Nobuaki; Ohtsuka, Noriaki; Tsuchiya, Kunihiko; Sano, Tadafumi; Nakajima, Ken; Homma, Ryohei; Kosuge, Fumiaki

2015-01-01

Development of the reactor measurement system was started to obtain the real-time in-core nuclear and thermal information, where the quantitative measurement of brightness of Cherenkov light was investigated. The system would be applied as a monitoring system in severe accidents and for the advanced operation management technology in existing LWRs. The calculation and the observation were performed to obtain the quantity of the Cherenkov light caused by the gamma and beta rays emitted from the fuels in the core of Kyoto University Research Reactor. The results indicate that the real-time reactor power can be estimated from the brightness of the Cherenkov light observed by a CCD camera. This method can also work for the estimation of the burn-up of spent fuels at commercial reactors. Since the observed brightness value of the Cherenkov light was influenced by the camera position, the optical observation method should be improved to achieve high accuracy observation. (author)

A Randomized Controlled Trial of Cognitive-Behavior Therapy Plus Bright Light Therapy for Adolescent Delayed Sleep Phase Disorder

Science.gov (United States)

Gradisar, Michael; Dohnt, Hayley; Gardner, Greg; Paine, Sarah; Starkey, Karina; Menne, Annemarie; Slater, Amy; Wright, Helen; Hudson, Jennifer L.; Weaver, Edward; Trenowden, Sophie

2011-01-01

Objective: To evaluate cognitive-behavior therapy plus bright light therapy (CBT plus BLT) for adolescents diagnosed with delayed sleep phase disorder (DSPD). Design: Randomized controlled trial of CBT plus BLT vs. waitlist (WL) control with comparisons at pre- and post-treatment. There was 6-month follow-up for the CBT plus BLT group only. Setting: Flinders University Child & Adolescent Sleep Clinic, Adelaide, South Australia. Patients: 49 adolescents (mean age 14.6 ± 1.0 y, 53% males) diagnosed with DSPD; mean chronicity 4 y 8 months; 16% not attending school. Eighteen percent of adolescents dropped out of the study (CBT plus BLT: N = 23 vs WL: N = 17). Interventions: CBT plus BLT consisted of 6 individual sessions, including morning bright light therapy to advance adolescents' circadian rhythms, and cognitive restructuring and sleep education to target associated insomnia and sleep hygiene. Measurements and Results: DSPD diagnosis was performed via a clinical interview and 7-day sleep diary. Measurements at each time-point included online sleep diaries and scales measuring sleepiness, fatigue, and depression symptoms. Compared to WL, moderate-to-large improvements (d = 0.65-1.24) were found at post-treatment for CBT plus BLT adolescents, including reduced sleep latency, earlier sleep onset and rise times, total sleep time (school nights), wake after sleep onset, sleepiness, and fatigue. At 6-month follow-up (N = 15), small-to-large improvements (d = 0.24-1.53) continued for CBT plus BLT adolescents, with effects found for all measures. Significantly fewer adolescents receiving CBT plus BLT met DPSD criteria at post-treatment (WL = 82% vs. CBT plus BLT = 13%, P sleep and daytime impairments in the immediate and long-term. Studies evaluating the treatment effectiveness of each treatment component are needed. Clinical Trial Information: Australia – New Zealand Trials Registry Number: ACTRN12610001041044. Citation: Gradisar M; Dohnt H; Gardner G; Paine S; Starkey

High brightness photonic band crystal semiconductor lasers in the passive mode locking regime

Energy Technology Data Exchange (ETDEWEB)

Rosales, R.; Kalosha, V. P.; Miah, M. J.; Bimberg, D. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany); Posilović, K. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany); PBC Lasers GmbH, Hardenbergstrasse 36, 10623 Berlin (Germany); Pohl, J.; Weyers, M. [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, Berlin 12489 (Germany)

2014-10-20

High brightness photonic band crystal lasers in the passive mode locking regime are presented. Optical pulses with peak power of 3 W and peak brightness of about 180 MW cm{sup −2} sr{sup −1} are obtained on a 5 GHz device exhibiting 15 ps pulses and a very low beam divergence in both the vertical and horizontal directions.

Studies on a laser driven photoemissive high-brightness electron source and novel photocathodes

International Nuclear Information System (INIS)

Geng Rongli; Song Jinhu; Yu Jin

1997-01-01

A laser driven photoemissive high-brightness electron source at Beijing University is reported. Through a DC accelerating gap of 100 kV voltage, the device is capable of delivering high-brightness electron beam of 35-100 ps pulse duration when irradiated with a mode-locked YAG laser. The geometry of the gun is optimized with the aid of simulation codes EGUN and POISSON. The results of experimental studies on ion implanted photocathode and cesium telluride photocathode are given. The proposed laser driven superconducting RF gun is also discussed

High mobility solution-processed hybrid light emitting transistors

International Nuclear Information System (INIS)

Walker, Bright; Kim, Jin Young; Ullah, Mujeeb; Burn, Paul L.; Namdas, Ebinazar B.; Chae, Gil Jo; Cho, Shinuk; Seo, Jung Hwa

2014-01-01

We report the design, fabrication, and characterization of high-performance, solution-processed hybrid (inorganic-organic) light emitting transistors (HLETs). The devices employ a high-mobility, solution-processed cadmium sulfide layer as the switching and transport layer, with a conjugated polymer Super Yellow as an emissive material in non-planar source/drain transistor geometry. We demonstrate HLETs with electron mobilities of up to 19.5 cm 2 /V s, current on/off ratios of >10 7 , and external quantum efficiency of 10 −2 % at 2100 cd/m 2 . These combined optical and electrical performance exceed those reported to date for HLETs. Furthermore, we provide full analysis of charge injection, charge transport, and recombination mechanism of the HLETs. The high brightness coupled with a high on/off ratio and low-cost solution processing makes this type of hybrid device attractive from a manufacturing perspective

A dual-directional light-control film with a high-sag and high-asymmetrical-shape microlens array fabricated by a UV imprinting process

International Nuclear Information System (INIS)

Lin, Ta-Wei; Liao, Yunn-Shiuan; Chen, Chi-Feng; Yang, Jauh-Jung

2008-01-01

A dual-directional light-control film with a high-sag and high-asymmetric-shape long gapless hexagonal microlens array fabricated by an ultra-violent (UV) imprinting process is presented. Such a lens array is designed by ray-tracing simulation and fabricated by a micro-replication process including gray-scale lithography, electroplating process and UV curing. The shape of the designed lens array is similar to that of a near half-cylindrical lens array with a periodical ripple. The measurement results of a prototype show that the incident lights using a collimated LED with the FWHM of dispersion angle, 12°, are diversified differently in short and long axes. The numerical and experimental results show that the FWHMs of the view angle for angular brightness in long and short axis directions through the long hexagonal lens are about 34.3° and 18.1° and 31° and 13°, respectively. Compared with the simulation result, the errors in long and short axes are about 5% and 16%, respectively. Obviously, the asymmetric gapless microlens array can realize the aim of the controlled asymmetric angular brightness. Such a light-control film can be used as a power saving screen compared with convention diffusing film for the application of a rear projection display

Signal processing for LED lighting systems : illumination rendering and sensing

NARCIS (Netherlands)

Yang, H.

2010-01-01

Solid state lighting, employing high brightness light emitting diodes (LEDs), is becoming increasingly widely used. The advantages of LEDs include high radiative efficiency, long lifetime, limited heat generation and superior tolerance to humidity. Another important advantage of LED lighting systems

Simultaneous Observations of p-mode Light Walls and Magnetic Reconnection Ejections above Sunspot Light Bridges

Energy Technology Data Exchange (ETDEWEB)

Hou, Yijun; Zhang, Jun; Li, Ting; Yang, Shuhong; Li, Xiaohong, E-mail: yijunhou@nao.cas.cn, E-mail: zjun@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2017-10-10

Recent high-resolution observations from the Interface Region Imaging Spectrograph reveal bright wall-shaped structures in active regions (ARs), especially above sunspot light bridges. Their most prominent feature is the bright oscillating front in the 1400/1330 Å channel. These structures are named light walls and are often interpreted to be driven by p-mode waves. Above the light bridge of AR 12222 on 2014 December 06, we observed intermittent ejections superimposed on an oscillating light wall in the 1400 Å passband. At the base location of each ejection, the emission enhancement was detected in the Solar Dynamics Observatory 1600 Å channel. Thus, we suggest that in wall bases (light bridges), in addition to the leaked p-mode waves consistently driving the oscillating light wall, magnetic reconnection could happen intermittently at some locations and eject the heated plasma upward. Similarly, in the second event occurring in AR 12371 on 2015 June 16, a jet was simultaneously detected in addition to the light wall with a wave-shaped bright front above the light bridge. At the footpoint of this jet, lasting brightening was observed, implying magnetic reconnection at the base. We propose that in these events, two mechanisms, p-mode waves and magnetic reconnection, simultaneously play roles in the light bridge, and lead to the distinct kinetic features of the light walls and the ejection-like activities, respectively. To illustrate the two mechanisms and their resulting activities above light bridges, in this study we present a cartoon model.

High-brightness electron source driven by laser

International Nuclear Information System (INIS)

Zhao Kui; Geng Rongli; Wang Lifang

1996-01-01

A DC high-brightness laser driven by photo emissive electron gun is being developed at Beijing University, in order to produce 50∼100 ps electron bunches of high quality. The gun consists of a photocathode preparation chamber and a DC acceleration cavity. Different ways of fabricating photocathode, such as chemical vapor deposition, ion beam implantation and ion beam enhanced deposition, can be adopted. The acceleration gap is designed with the aid of simulation codes EGUN and POISSON. 100 kV DC high voltage is fed to the anode through a careful designed ceramic insulator. The laser system is a mode locked Nd-YAG oscillator proceeded by an amplifier at 10 Hz repetition rate, which can deliver three different wavelength (1064/532/266 nm). The combination of a superconducting cavity with the photocathode preparation chamber is discussed

Multiwavelength Study of Gamma-Ray Bright Blazars

Science.gov (United States)

Morozova, Daria; Larionov, V. M.; Hagen-Thorn, V. A.; Jorstad, S. G.; Marscher, A. P.; Troitskii, I. S.

2011-01-01

We investigate total intensity radio images of 6 gamma-ray bright blazars (BL Lac, 3C 279, 3C 273, W Com, PKS 1510-089, and 3C 66A) and their optical and gamma-ray light curves to study connections between gamma-ray and optical brightness variations and changes in the parsec-scale radio structure. We use high-resolution maps obtained by the BU group at 43 GHz with the VLBA, optical light curves constructed by the St.Petersburg State U. (Russia) team using measurements with the 0.4 m telescope of St.Petersburg State U. (LX200) and the 0.7 m telescope of the Crimean Astrophysical Observatory (AZT-8), and gamma-ray light curves, which we have constructed with data provided by the Fermi Large Area Telescope. Over the period from August 2008 to November 2009, superluminal motion is found in all 6 objects with apparent speed ranging from 2c to 40c. The blazars with faster apparent speeds, 3C 273, 3C 279, PKS 1510-089, and 3C 66A, exhibit stronger variability of the gamma-ray emission. There is a tendency for sources with sharply peaked gamma-ray flares to have faster jet speed than sources with gamma-ray light curves with no sharp peaks. Gamma-ray light curves with sharply peaked gamma-ray flares possess a stronger gamma-ray/optical correlations. The research at St.Petersburg State U. was funded by the Minister of Education and Science of the Russian Federation (state contract N#P123). The research at BU was funded in part by NASA Fermi Guest Investigator grant NNX08AV65G and by NSF grant AST-0907893. The VLBA is an instrument of the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Very-High-Brightness Picosecond Electron Source

International Nuclear Information System (INIS)

Bluem, H.

2003-01-01

Bright, RF photocathode electron guns are the source of choice for most high-performance research accelerator applications. Some of these applications are pushing the performance boundaries of the present state-of-the-art guns. Advanced Energy Systems is developing a novel photocathode RF gun that shows excellent promise for extending gun performance. Initial gun simulations with only a short booster accelerator easily break the benchmark emittance of one micron for 1 nC of bunch charge. The pulse length in these simulations is less than 2 ps. It is expected that with more detailed optimization studies, the performance can be further improved. The performance details of the gun will be presented. In addition, we will discuss the present design concept along with the status of the project

Progress of OLED devices with high efficiency at high luminance

Science.gov (United States)

Nguyen, Carmen; Ingram, Grayson; Lu, Zhenghong

2014-03-01

Organic light emitting diodes (OLEDs) have progressed significantly over the last two decades. For years, OLEDs have been promoted as the next generation technology for flat panel displays and solid-state lighting due to their potential for high energy efficiency and dynamic range of colors. Although high efficiency can readily be obtained at low brightness levels, a significant decline at high brightness is commonly observed. In this report, we will review various strategies for achieving highly efficient phosphorescent OLED devices at high luminance. Specifically, we will provide details regarding the performance and general working principles behind each strategy. We will conclude by looking at how some of these strategies can be combined to produce high efficiency white OLEDs at high brightness.

Do Low Surface Brightness Galaxies Host Stellar Bars?

International Nuclear Information System (INIS)

Cervantes Sodi, Bernardo; Sánchez García, Osbaldo

2017-01-01

With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness is mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.

Do Low Surface Brightness Galaxies Host Stellar Bars?

Energy Technology Data Exchange (ETDEWEB)

Cervantes Sodi, Bernardo; Sánchez García, Osbaldo, E-mail: b.cervantes@irya.unam.mx, E-mail: o.sanchez@irya.unam.mx [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia, A.P. 3-72, C.P. 58089 Michoacán, México (Mexico)

2017-09-20

With the aim of assessing if low surface brightness galaxies host stellar bars and by studying the dependence of the occurrence of bars as a function of surface brightness, we use the Galaxy Zoo 2 data set to construct a large volume-limited sample of galaxies and then segregate these galaxies as having low or high surface brightness in terms of their central surface brightness. We find that the fraction of low surface brightness galaxies hosting strong bars is systematically lower than that found for high surface brightness galaxies. The dependence of the bar fraction on the central surface brightness is mostly driven by a correlation of the surface brightness with the spin and the gas richness of the galaxies, showing only a minor dependence on the surface brightness. We also find that the length of the bars is strongly dependent on the surface brightness, and although some of this dependence is attributed to the gas content, even at a fixed gas-to-stellar mass ratio, high surface brightness galaxies host longer bars than their low surface brightness counterparts, which we attribute to an anticorrelation of the surface brightness with the spin.

Lightness functions

DEFF Research Database (Denmark)

Campi, Stefano; Gardner, Richard; Gronchi, Paolo

2012-01-01

Variants of the brightness function of a convex body K in n-dimensional Euclidean are investigated. The Lambertian lightness function L(K; v , w ) gives the total reflected light resulting from illumination by a light source at infinity in the direction w that is visible when looking...... in the direction v . The partial brightness function R( K ; v , w ) gives the area of the projection orthogonal to v of the portion of the surface of K that is both illuminated by a light source from the direction w and visible when looking in the direction v . A class of functions called lightness functions...... is introduced that includes L(K;.) and R(K;.) as special cases. Much of the theory of the brightness function like uniqueness, stability, and the existence and properties of convex bodies of maximal and minimal volume with finitely many function values equal to those of a given convex body, is extended...

The new world atlas of artificial night sky brightness.

Science.gov (United States)

Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C M; Elvidge, Christopher D; Baugh, Kimberly; Portnov, Boris A; Rybnikova, Nataliya A; Furgoni, Riccardo

2016-06-01

Artificial lights raise night sky luminance, creating the most visible effect of light pollution-artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world's land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights.

Blue Light Enhances Bacterial Clearance and Reduces Organ Injury During Sepsis.

Science.gov (United States)

Lewis, Anthony J; Zhang, Xianghong; Griepentrog, John E; Yuan, Du; Collage, Richard D; Waltz, Paul K; Angus, Derek C; Zuckerbraun, Brian S; Rosengart, Matthew R

2018-05-04

The physiology of nearly all mammalian organisms are entrained by light and exhibit circadian rhythm. The data derived from animal studies show that light influences immunity, and these neurophysiologic pathways are maximally entrained by the blue spectrum. Here, we hypothesize that bright blue light reduces acute kidney injury by comparison with either bright red or standard, white fluorescent light in mice subjected to sepsis. To further translational relevance, we performed a pilot clinical trial of blue light therapy in human subjects with appendicitis. Laboratory animal research, pilot human feasibility trial. University basic science laboratory and tertiary care hospital. Male C57BL/6J mice, adult (> 17 yr) patients with acute appendicitis. Mice underwent cecal ligation and puncture and were randomly assigned to a 24-hour photoperiod of bright blue, bright red, or ambient white fluorescent light. Subjects with appendicitis were randomized to receive postoperatively standard care or standard care plus high-illuminance blue light. Exposure to bright blue light enhanced bacterial clearance from the peritoneum, reduced bacteremia and systemic inflammation, and attenuated the degree of acute kidney injury. The mechanism involved an elevation in cholinergic tone that augmented tissue expression of the nuclear orphan receptor REV-ERBα and occurred independent of alterations in melatonin or corticosterone concentrations. Clinically, exposure to blue light after appendectomy was feasible and reduced serum interleukin-6 and interleukin-10 concentrations. Modifying the spectrum of light may offer therapeutic utility in sepsis.

Dark-Bright Soliton Dynamics Beyond the Mean-Field Approximation

Science.gov (United States)

Katsimiga, Garyfallia; Koutentakis, Georgios; Mistakidis, Simeon; Kevrekidis, Panagiotis; Schmelcher, Peter; Theory Group of Fundamental Processes in Quantum Physics Team

2017-04-01

The dynamics of dark bright solitons beyond the mean-field approximation is investigated. We first examine the case of a single dark-bright soliton and its oscillations within a parabolic trap. Subsequently, we move to the setting of collisions, comparing the mean-field approximation to that involving multiple orbitals in both the dark and the bright component. Fragmentation is present and significantly affects the dynamics, especially in the case of slower solitons and in that of lower atom numbers. It is shown that the presence of fragmentation allows for bipartite entanglement between the distinguishable species. Most importantly the interplay between fragmentation and entanglement leads to the decay of each of the initial mean-field dark-bright solitons into fast and slow fragmented dark-bright structures. A variety of excitations including dark-bright solitons in multiple (concurrently populated) orbitals is observed. Dark-antidark states and domain-wall-bright soliton complexes can also be observed to arise spontaneously in the beyond mean-field dynamics. Deutsche Forschungsgemeinschaft (DFG) in the framework of the SFB 925 ``Light induced dynamics and control of correlated quantum systems''.

Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV

Energy Technology Data Exchange (ETDEWEB)

Wang, He [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Xu, Yiming [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Ulonska, Stefan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Robinson, Joseph S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Ranitovic, Predrag [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Kaindl, Robert A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division

2015-06-11

Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. In this article, we demonstrate a highly-efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ≈3 × 10¹³ s^-1 is generated at 22.3 eV, with 5 × 10^-5 conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders-of-magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase matching, confirmed by simulations. Finally, spectral isolation of a single 72-meV-wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications.

High-brightness high-order harmonic generation at 13 nm with a long gas jet

International Nuclear Information System (INIS)

Kim, Hyung Taek; Kim, I Jong; Lee, Dong Gun; Park, Jong Ju; Hong, Kyung Han; Nam, Chang Hee

2002-01-01

The generation of high-order harmonics is well-known method producing coherent extreme-ultraviolet radiation with pulse duration in the femtosecond regime. High-order harmonics have attracted much attention due to their unique features such as coherence, ultrashort pulse duration, and table-top scale system. Due to these unique properties, high-order harmonics have many applications of atomic and molecular spectroscopy, plasma diagnostics and solid-state physics. Bright generation of high-order harmonics is important for actual applications. Especially, the generation of strong well-collimated harmonics at 13 nm can be useful for the metrology of EUV lithography optics because of the high reflectivity of Mo-Si mirrors at this wavelength. The generation of bright high-order harmonics is rather difficult in the wavelength region below 15nm. Though argon and xenon gases have large conversion efficiency, harmonic generation from these gases is restricted to wavelengths over 20 nm due to low ionization potential. Hence, we choose neon for the harmonic generation around 13 nm; it has larger conversion efficiency than helium and higher ionization potential than argon. In this experiment, we have observed enhanced harmonic generation efficiency and low beam divergence of high-order harmonics from a elongated neon gas jet by the enhancement of laser propagation in an elongated gas jet. A uniform plasma column was produced when the gas jet was exposed to converging laser pulses.

Galaxy Size Evolution at High Redshift and Surface Brightness Selection Effects: Constraints from the Hubble Ultra Deep Field

Science.gov (United States)

Bouwens, R. J.; Illingworth, G. D.; Blakeslee, J. P.; Broadhurst, T. J.; Franx, M.

2004-08-01

We use the exceptional depth of the Ultra Deep Field (UDF) and UDF-parallel Advanced Camera for Surveys fields to study the sizes of high-redshift (z~2-6) galaxies and address long-standing questions about possible biases in the cosmic star formation rate due to surface brightness dimming. Contrasting B-, V-, and i-dropout samples culled from the deeper data with those obtained from the shallower Great Observatories Origins Deep Survey fields, we demonstrate that the shallower data are essentially complete at bright magnitudes to z~0.4", >~3 kpc) low surface brightness galaxies are rare. A simple comparison of the half-light radii of the Hubble Deep Field-North + Hubble Deep Field-South U-dropouts with B-, V-, and i-dropouts from the UDF shows that the sizes follow a (1+z)-1.05+/-0.21 scaling toward high redshift. A more rigorous measurement compares different scalings of our U-dropout sample with the mean profiles for a set of intermediate-magnitude (26.0dropouts from the UDF. The best fit is found with a (1+z)-0.94+0.19-0.25 size scaling (for fixed luminosity). This result is then verified by repeating this experiment with different size measures, low-redshift samples, and magnitude ranges. Very similar scalings are found for all comparisons. A robust measurement of size evolution is thereby demonstrated for galaxies from z~6 to 2.5 using data from the UDF. Based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Brightness and transparency in the early visual cortex.

Science.gov (United States)

Salmela, Viljami R; Vanni, Simo

2013-06-24

Several psychophysical studies have shown that transparency can have drastic effects on brightness and lightness. However, the neural processes generating these effects have remained unresolved. Several lines of evidence suggest that the early visual cortex is important for brightness perception. While single cell recordings suggest that surface brightness is represented in the primary visual cortex, the results of functional magnetic resonance imaging (fMRI) studies have been discrepant. In addition, the location of the neural representation of transparency is not yet known. We investigated whether the fMRI responses in areas V1, V2, and V3 correlate with brightness and transparency. To dissociate the blood oxygen level-dependent (BOLD) response to brightness from the response to local border contrast and mean luminance, we used variants of White's brightness illusion, both opaque and transparent, in which luminance increments and decrements cancel each other out. The stimuli consisted of a target surface and a surround. The surround luminance was always sinusoidally modulated at 0.5 Hz to induce brightness modulation to the target. The target luminance was constant or modulated in counterphase to null brightness modulation. The mean signal changes were calculated from the voxels in V1, V2, and V3 corresponding to the retinotopic location of the target surface. The BOLD responses were significantly stronger for modulating brightness than for stimuli with constant brightness. In addition, the responses were stronger for transparent than for opaque stimuli, but there was more individual variation. No interaction between brightness and transparency was found. The results show that the early visual areas V1-V3 are sensitive to surface brightness and transparency and suggest that brightness and transparency are represented separately.

Simulations of Beam Optics and Bremsstrahlung for High Intensity and Brightness Channeling Radiation

Energy Technology Data Exchange (ETDEWEB)

Hyun, J. [Sokendai, Tsukuba; Piot, P. [NIU, DeKalb; Sen, T. [Fermilab

2018-04-12

This paper presents X-ray spectra of channeling radiation expected at the FAST (Fermi Accelerator Science and Technology) facility in Fermilab. Our purpose is to produce high brightness quasi-monochromatic X-rays in an energy range from 40 keV to 110 keV. We will use a diamond crystal and low emittance electrons with an energy of around 43 MeV. The quality of emitted X-rays depends on parameters of the electron beam at the crystal. We present simulations of the beam optics for high brightness and high yield operations for a range of bunch charges. We estimate the X-ray spectra including bremsstrahlung background. We discuss how the electron beam distributions after the diamond crystal are affected by channeling. We discuss an X-ray detector system to avoid pile-up effects during high charge operations.

Generation of high brightness ion beam from insulated anode PED

International Nuclear Information System (INIS)

Matsukawa, Yoshinobu

1988-01-01

Generation and focusing of a high density ion beam with high brightness from a organic center part of anode of a PED was reported previously. Mass, charge and energy distribution of this beam were analyzed. Three kind of anode were tried. Many highly ionized medium mass ions (up to C 4+ , O 6+ ) accelarated to several times of voltage difference between anode and cathode were observed. In the case of all insulator anode the current carried by the medium mass ions is about half of that carried by protons. (author)

A comprehensive radio view of the extremely bright gamma-ray burst 130427A

NARCIS (Netherlands)

van der Horst, A.J.; Paragi, Z.; de Bruyn, A.G.; Granot, J.; Kouveliotou, C.; Wiersema, K.; Starling, R.L.C.; Curran, P.A.; Wijers, R.A.M.J.; Rowlinson, A.; Anderson, G.A.; Fender, R.P.; Yang, J.; Strom, R.G.

2014-01-01

GRB 130427A was extremely bright as a result of occurring at low redshift whilst the energetics were more typical of high-redshift gamma-ray bursts (GRBs). We collected well-sampled light curves at 1.4 and 4.8 GHz of GRB 130427A with the Westerbork Synthesis Radio Telescope (WSRT); and we obtained

A comprehensive radio view of the extremely bright gamma-ray burst 130427A

NARCIS (Netherlands)

van der Horst, A. J.; Paragi, Z.; de Bruyn, A. G.; Granot, J.; Kouveliotou, C.; Wiersema, K.; Starling, R. L. C.; Curran, P. A.; Wijers, R. A. M. J.; Rowlinson, A.; Anderson, G. A.; Fender, R. P.; Yang, J.; Strom, R. G.

GRB 130427A was extremely bright as a result of occurring at low redshift whilst the energetics were more typical of high-redshift gamma-ray bursts (GRBs). We collected well-sampled light curves at 1.4 and 4.8 GHz of GRB 130427A with the Westerbork Synthesis Radio Telescope (WSRT); and we obtained

Planned High-brightness Channeling Radiation Experiment at Fermilab's Advanced Superconducting Test Accelerator

Energy Technology Data Exchange (ETDEWEB)

Blomberg, Ben [NICADD, DeKalb; Mihalcea, Daniel [NICADD, DeKalb; Panuganti, Harsha [NICADD, DeKalb; Piot, Philippe [Fermilab; Brau, Charles [Vanderbilt U.; Choi, Bo [Vanderbilt U.; Gabella, William [Vanderbilt U.; Ivanov, Borislav [Vanderbilt U.; Mendenhall, Marcus [Vanderbilt U.; Lynn, Christopher [Swarthmore Coll.; Sen, Tanaji [Fermilab; Wagner, Wolfgang [Forschungszentrum Dresden Rossendorf

2014-07-01

In this contribution we describe the technical details and experimental setup of our study aimed at producing high-brightness channeling radiation (CR) at Fermilab’s new user facility the Advanced Superconducting Test Accelerator (ASTA). In the ASTA photoinjector area electrons are accelerated up to 40-MeV and focused to a sub-micron spot on a ~40 micron thick carbon diamond, the electrons channel through the crystal and emit CR up to 80-KeV. Our study utilizes ASTA’s long pulse train capabilities and ability to preserve ultra-low emittance, to produce the desired high average brightness.

Bright lights, big city: influences of ecological light pollution on reciprocal stream-riparian invertebrate fluxes.

Science.gov (United States)

Meyer, Lars A; Sullivan, S Mazeika P

2013-09-01

Cities produce considerable ecological light pollution (ELP), yet the effects of artificial night lighting on biological communities and ecosystem function have not been fully explored. From June 2010 to June 2011, we surveyed aquatic emergent insects, riparian arthropods entering the water, and riparian spiders of the family Tetragnathidae at nine stream reaches representing common ambient ELP levels of Columbus, Ohio, USA, streams (low, 0.1-0.5 lux; moderate, 0.6-2.0 lux; high, 2.1-4.0 lux). In August 2011, we experimentally increased light levels at the low- and moderate-treatment reaches to 10-12 lux to represent urban streams exposed to extremely high levels of ELP. Although season exerted the dominant influence on invertebrate fluxes over the course of the year, when analyzed by season, we found that light strongly influenced multiple invertebrate responses. The experimental light addition resulted in a 44% decrease in tetragnathid spider density (P = 0.035), decreases of 16% in family richness (P = 0.040) and 76% in mean body size (P = 0.022) of aquatic emergent insects, and a 309% increase in mean body size of terrestrial arthropods (P = 0.015). Our results provide evidence that artificial light sources can alter community structure and ecosystem function in streams via changes in reciprocal aquatic-terrestrial fluxes of invertebrates.

The star-bright hour : [luuletused] / Betti Alver

Index Scriptorium Estoniae

Alver, Betti, 1906-1989

2006-01-01

Sisu: The star-bright hour ; Not a dream ; The Piper ; Corals in an ancent river. Luuletused pärinevad kogumikust "Tuulelaeval valgusest on aerud = Windship with Oars of Light. (Tallinn : Huma, 2001). Orig.: Tähetund ; Mitte viirastus, meelepett ; Vilepuhuja ; Korallid Emajões

Brightness waves of electroluminescence in ZnO:La electroluminor

International Nuclear Information System (INIS)

Bhushan, S.; Pandey, A.N.; Kaza, Balakrishna Rao

1979-01-01

A cryostat for the measurement of different luminescent characteristics from liquid N 2 temperature to above has been fabricated. Using this cryostat brightness waves due to sinusoidal excitations for ZnO:La electroluminor (EL) has been studied at different temperatures from -168deg C. Brightness waves for this system consist of two primary peaks during each cycle of excitation. Each primary peak is associated with a secondary peak. This secondary peak at -168deg C exists at the left arm of the primary peak. As the temperature is increased to 18deg C it moves towards the right arm of the primary peak. At an intermediate temperature the secondary peaks are most pronounced. Possible mechanism for these phenomena have been discussed. Temperature dependence of time averaged EL brightness for this system has also been studied and three peaks have been found. The results of brightness waves have also been discussed in the light of temperature dependence of time averaged EL brightness. (auth.)

Intrinsic brightness temperatures of blazar jets at 15 GHz

Directory of Open Access Journals (Sweden)

Hovatta Talvikki

2013-12-01

Full Text Available We have developed a new Bayesian Markov Chain Monte Carlo method to deconvolve light curves of blazars into individual flares, including proper estimation of the fit errors. We use the method to fit 15GHzlight curves obtained within the OVRO 40-m blazar monitoring program where a large number of AGN have been monitored since 2008 in support of the Fermi Gamma-Ray Space Telescope mission. The time scales obtained from the fitted models are used to calculate the variability brightness temperature of the sources. Additionally, we have calculated brightness temperatures of a sample of these objects using Very Long Baseline Array data from the MOJAVE survey. Combining these two data sets enables us to study the intrinsic brightness temperature distribution in these blazars at 15 GHz. Our preliminary results indicate that the mean intrinsic brightness temperature in a sample of 14 sources is near the equipartition brightness temperature of ~ 1011K.

Strategies for the design of bright upconversion nanoparticles for bioanalytical applications

Science.gov (United States)

Wiesholler, Lisa M.; Hirsch, Thomas

2018-06-01

In recent years upconversion nanoparticles (UCNPs) received great attention because of their outstanding optical properties. Especially in bioanalytical applications this class of materials can overcome limitations of common probes like high background fluorescence or blinking. Nevertheless, the requirements for UCNPs to be applicable in biological samples, e.g. small size, water-dispersibility, excitation at low power density are in contradiction with the demand of high brightness. Therefore, a lot of attention is payed to the enhancement of the upconversion luminescence. This review discuss the recent trends and strategies to boost the brightness of UCNPs, classified in three main directions: a) improving the efficiency of energy absorption by the sensitizer via coupling to plasmonic or photonic structures or via attachment of ligands for light harvesting; b) minimizing non-radiative deactivation by variations in the architecture of UCNPs; and c) changing the excitation wavelength to get bright particles at low excitation power density for applications in aqueous systems. These strategies are critically reviewed including current limitations as well as future perspectives for the design of efficient UCNPs especially for sensing application in biological samples or cells.

High Brightness Injectors Based On Photocathode DC Gun

International Nuclear Information System (INIS)

B. Yunn

2001-01-01

Sample results of new injector design method based on a photocathode dc gun are presented, based on other work analytically proving the validity of the emittance compensation scheme for the case even when beam bunching is involved. We have designed several new injectors appropriate for different bunch charge ranges accordingly. Excellent beam quality produced by these injectors clearly shows that a photocathode dc gun can compete with a rf gun on an equal footing as the source of an electron beam for the bunch charge ranging up to 2 nano Coulomb (nC). This work therefore elevates a dc gun based injector to the preferred choice for many ongoing high brightness accelerator projects considering the proven operational stability and high average power capability of the dc gun

On the Feasibility of Very-Low-Density Pure Metal Foams as Bright High-Energy X-ray Sources

Science.gov (United States)

Colvin, Jeffrey; Felter, Thomas

2003-10-01

We have used the Busquet approximation (M. Busquet, Phys. Fluids B 5(11), 4191 (1993)) to explore calculationally what the possible x-ray conversion efficiencies into the K-band would be from irradiating very-low-density pure metal foams with tens of kilojoules of 1/3-micron laser light. We will discuss the advantages of pure metal foams as bright high-energy x-ray sources, and some results of this calculational study. We will also present our ideas for how to fabricate pure metal foams with densities of a few milligrams per cubic centimeter. This work was performed under the auspices of the US Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Effectiveness of recycling light in ultra-bright short-arc discharge lamps.

Science.gov (United States)

Malul, Asher; Nakar, Doron; Feuermann, Daniel; Gordon, Jeffrey M

2007-10-17

Recycling light back into a plasma lamp's radiant zone can enhance its radiance. Measurements are reported for the effectiveness, spectral properties and modified plasma radiance maps that result from light recycling with a specular hemispherical mirror in commercial 150 W ultrabright Xenon short-arc discharge lamps, motivated by projection, biomedical and high-temperature furnace applications. For certain spectral windows and plasma arc regions, radiance can be heightened by up to 70%. However, the overall light recycling efficiency is reduced to about half this value due to lamp geometry. The manner in which light-plasma interactions affect light recycling efficacy is also elucidated.

Energy-exchange collisions of dark-bright-bright vector solitons.

Science.gov (United States)

Radhakrishnan, R; Manikandan, N; Aravinthan, K

2015-12-01

We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices.

Bright to Dim Oscillatory Response of the Neurospora Circadian Oscillator

OpenAIRE

Gooch, Van D.; Johnson, Alicia E.; Larrondo, Luis F.; Loros, Jennifer J.; Dunlap, Jay C.

2014-01-01

The fungus Neurospora crassa constitutes an important model system extensively used in chronobiology. Several studies have addressed how environmental cues, such as light, can reset or synchronize a circadian system. By means of an optimized firefly luciferase reporter gene and a controllable lighting system, we show that Neurospora can display molecular circadian rhythms in dim light when cultures receive bright light prior to entering dim light conditions. We refer to this behavior as the “...

Influence of Type of Electric Bright Light on the Attraction of the African Giant Water Bug, Lethocerus indicus (Hemiptera: Belostomatidae

Directory of Open Access Journals (Sweden)

Luke Chinaru Nwosu

2012-01-01

Full Text Available This study investigated the influence of type of electric bright light (produced by fluorescent light tube and incandescent light bulb on the attraction of the African giant water bug, Lethocerus indicus (Hemiptera: Belostomatidae. Four fluorescent light tubes of 15 watts each, producing white-coloured light and four incandescent light bulbs of 60 watts each, producing yellow-coloured light, but both producing the same amount of light, were varied and used for the experiments. Collections of bugs at experimental house were done at night between the hours of 8.30 pm and 12 mid-night on daily basis for a period of four months per experiment in the years 2008 and 2009. Lethocerus indicus whose presence in any environment has certain implications was the predominant belostomatid bug in the area. Use of incandescent light bulbs in 2009 significantly attracted more Lethocerus indicus 103 (74.6% than use of fluorescent light tubes 35 (25.41% in 2008 [4.92=0.0001]. However, bug’s attraction to light source was not found sex dependent [>0.05; (>0.18=0.4286 and >0.28=0.3897]. Therefore, this study recommends the use of fluorescent light by households, campgrounds, and other recreational centres that are potentially exposed to the nuisance of the giant water bugs. Otherwise, incandescent light bulbs should be used when it is desired to attract the presence of these aquatic bugs either for food or scientific studies.

High Resolution Near Infrared Spectrometer to Study the Zodiacal Light Spectrum

Science.gov (United States)

Kutyrev, Alexander; Arendt, R.; Dwek, E.; Moseley, S. H.; Silverberg, R.; Rapchun, D.

2007-12-01

We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the near infrared region. R. Reynolds at el. (2004, ApJ 612, 1206) demonstrated that observing single Fraunhofer line can be a powerful tool for extracting zodiacal light parameters based on their measurements of the profile of the Mg I line at 5184 A. We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal emission from the DIRBE measurements to get a much higher quality measurement of the extragalactic IR background. The instrument design is based on a dual Fabry-Perot interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to reject the bright out of band telluric OH emission. High spectral contrast is absolutely necessary to achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design, estimated performance of the instrument with the expected results of the observing program. The project is supported by NASA ROSES-APRA grant.

A case study on large-scale dynamical influence on bright band using cloud radar during the Indian summer monsoon

Science.gov (United States)

Jha, Ambuj K.; Kalapureddy, M. C. R.; Devisetty, Hari Krishna; Deshpande, Sachin M.; Pandithurai, G.

2018-02-01

The present study is a first of its kind attempt in exploring the physical features (e.g., height, width, intensity, duration) of tropical Indian bright band using a Ka-band cloud radar under the influence of large-scale cyclonic circulation and attempts to explain the abrupt changes in bright band features, viz., rise in the bright band height by 430 m and deepening of the bright band by about 300 m observed at around 14:00 UTC on Sep 14, 2016, synoptically as well as locally. The study extends the utility of cloud radar to understand how the bright band features are associated with light precipitation, ranging from 0 to 1.5 mm/h. Our analysis of the precipitation event of Sep 14-15, 2016 shows that the bright band above (below) 3.7 km, thickness less (more) than 300 m can potentially lead to light drizzle of 0-0.25 mm/h (drizzle/light rain) at the surface. It is also seen that the cloud radar may be suitable for bright band study within light drizzle limits than under higher rain conditions. Further, the study illustrates that the bright band features can be determined using the polarimetric capability of the cloud radar. It is shown that an LDR value of - 22 dB can be associated with the top height of bright band in the Ka-band observations which is useful in the extraction of the bright band top height and its width. This study is useful for understanding the bright band phenomenon and could be potentially useful in establishing the bright band-surface rain relationship through the perspective of a cloud radar, which would be helpful to enhance the cloud radar-based quantitative estimates of precipitation.

The Los Alamos high-brightness photoinjector

Energy Technology Data Exchange (ETDEWEB)

O' Shea, P.G.

1991-01-01

For a number of years Los Alamos National Laboratory has been developing photocathode RF guns for high-brightness electron beam applications such as free-electron lasers (FELs). Previously thermionic high-voltage guns have been the source of choice for the electron accelerators used to drive FELs. The performance of such FELs is severely limited by the emittance growth produced by the subharmonic bunching process and also by the low peak current of the source. In a photoinjector, a laser driven photocathode is placed directly in a high-gradient RF accelerating cavity. A photocathode allows unsurpassed control over the current, and the spatial and temporal profile of the beam. In addition the electrodeless emission'' avoids many of the difficulties associated with multi-electrode guns, i.e. the electrons are accelerated very rapidly to relativistic energies, and there are no electrodes to distort the accelerating fields. For the past two years we have been integrating a photocathode into our existing FEL facility by replacing our thermionic gun and subharmonic bunchers with a high-gradient 1.3 GHz photoinjector. The photoinjector, which is approximately 0.6 m in length, produces 6 MeV, 300 A, 15 ps linac, and accelerated to a final energy of 40 MeV. We have recently begun lasing at wavelengths near 3 {mu}m. 16 refs., 2 figs., 5 tabs.

The effect of a change in sleep-wakefulness timing, bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature.

Science.gov (United States)

Iskra-Golec, I; Fafrowicz, M; Marek, T; Costa, G; Folkard, S; Foret, J; Kundi, M; Smith, L

2001-12-01

Experiments consisting of baseline, bright light and physical exercise studies were carried out to compare the effect of a 9-hour delay in sleep-wakefulness timing, and the effects of bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature were examined. Each study comprised a 24-hour constant routine at the beginning followed by 3 night shifts and 24-hour constant routine at the end. Performance on tasks differing in cognitive load, mood and body temperature was measured during each constant routine and the interventions were applied during the night shifts. The 24-hour pattern of alertness and performance on the tasks with low cognitive load in post-treatment conditions followed the change in sleep-wakefulness timing while more cognitively loaded tasks tended to show a reverse trend when compared to pre-treatment conditions. There was a phase delay around 4 hours in circadian rhythms of body temperature in post-treatment conditions.

Fuselage mounted anti-collision lights utilizing high power LEDs

Science.gov (United States)

Lundberg, John; Machi, Nicolo; Mangum, Scott; Singer, Jeffrey

2005-09-01

As LEDs continue to improve in efficacy and total light output, they are increasingly finding their way in to new applications in the aviation industry as well as adjacent markets. One function that is particularly challenging and may reap substantial benefits from this new technology is the fuselage mounted anti-collision light. Anti-collision lights provide conspicuity for the aircraft by periodically emitting bright flashes of light. The color, light distribution and intensity levels for these lights are all closely regulated through Federal Aviation Regulation (FAR) documents. These lighting requirements, along with thermal, environmental and aerodynamic requirements, drive the overall design. In this paper, we will discuss the existing technologies used in anti-collision lights and the advantages and challenges associated with an LED solution. Particular attention will be given to the optical, thermal, electrical and aerodynamic aspects associated with an LED approach. A specific case study will be presented along with some of the challenges that have arisen during the design process. These challenges include the addition of an integrated covert anti-collision lighting.

Bright light therapy as part of a multicomponent management program improves sleep and functional outcomes in delirious older hospitalized adults.

Science.gov (United States)

Chong, Mei Sian; Tan, Keng Teng; Tay, Laura; Wong, Yoke Moi; Ancoli-Israel, Sonia

2013-01-01

Delirium is associated with poor outcomes following acute hospitalization. A specialized delirium management unit, the Geriatric Monitoring Unit (GMU), was established. Evening bright light therapy (2000-3000 lux; 6-10 pm daily) was added as adjunctive treatment, to consolidate circadian activity rhythms and improve sleep. This study examined whether the GMU program improved sleep, cognitive, and functional outcomes in delirious patients. A total of 228 patients (mean age = 84.2 years) were studied. The clinical characteristics, delirium duration, delirium subtype, Delirium Rating Score (DRS), cognitive status (Chinese Mini-Mental State Examination), functional status (modified Barthel Index [MBI]), and chemical restraint use during the initial and predischarge phase of the patient's GMU admission were obtained. Nurses completed hourly 24-hour patient sleep logs, and from these, the mean total sleep time, number of awakenings, and sleep bouts (SB) were computed. The mean delirium duration was 6.7 ± 4.6 days. Analysis of the delirium subtypes showed that 18.4% had hypoactive delirium, 30.2% mixed delirium, and 51.3% had hyperactive delirium. There were significant improvements in MBI scores, especially for the hyperactive and mixed delirium subtypes (P hours) (P hours) (P bright light therapy as part of a multicomponent delirium management program. The benefits appear to have occurred mainly in patients with hyperactive delirium, which merits further in-depth, randomized controlled studies.

OLEDs for lighting: new approaches

Science.gov (United States)

Duggal, Anil R.; Foust, Donald F.; Nealon, William F.; Heller, Christian M.

2004-02-01

OLED technology has improved to the point where it is now possible to envision developing OLEDs as a low cost solid state light source. In order to realize this, significant advances have to be made in device efficiency, lifetime at high brightness, high throughput fabrication, and the generation of illumination quality white light. In this talk, the requirements for general lighting will be reviewed and various approaches to meeting them will be outlined. Emphasis will be placed on a new monolithic series-connected OLED design architecture that promises scalability without high fabrication cost or design complexity.

High brightness beams and applications

International Nuclear Information System (INIS)

Sheffield, R.L.

1995-01-01

This paper describes the present research on attaining intense bright electron beams. Thermionic systems are briefly covered. Recent and past results from the photoinjector programs are given. The performance advantages and difficulties presently faced by researchers using photoinjectors is discussed. The progress that has been made in photocathode materials, both in lifetime and quantum efficiency, is covered. Finally, a discussion of emittance measurements of photoinjector systems and how the measurement is complicated by the non-thermal nature of the electron beam is presented

Effects of evening light conditions on salivary melatonin of Japanese junior high school students

Directory of Open Access Journals (Sweden)

Harada Tetsuo

2004-08-01

Full Text Available Abstract Background In a previous study, when adult subjects were exposed to a level of 400 lux light for more than 30 min or a level of 300 lux light for more than 2 hours, salivary melatonin concentration during the night dropped lower than when the subjects were exposed to dim illumination. It was suggested that such light exposure in adolescents or children during the first half of subjective night in normal life might decrease the melatonin level and prevent the falling into sleep. However, there has been no actual study on the effects of light exposure in adolescents. Methods Effects of exposure to the bright light (2000 lux from fluorescent light bulbs during a period of three hours from 19:30 to 22:30 in one evening were examined on evening salivary melatonin concentrations from 19:45 to 23:40. The control group was exposed to dim light (60 lux during these three hours. Both the dim light control group [DLCG] and the bright light experimental group [BLEG] consisted of two female and three male adolescent participants aged 14–15 y. Results The salivary melatonin level increased rapidly from 3.00 pg/ml at 21:45 to 9.18 pg/ml at 23:40 in DLCG, whereas it remained at less than 1.3 pg/ml for the three hours in BLEG. Melatonin concentration by BLEG at 22:30 of the experimental day was lower than that at the same time on the day before the experimental day, whereas it was significantly higher in the experimental day than on the day before the experimental day in DLCG. Conclusions Bright lights of 2000 lux and even moderate lights of 200–300 lux from fluorescent light bulbs can inhibit nocturnal melatonin concentration in adolescents. Ancient Japanese lighting from a traditional Japanese hearth, oil lamp or candle (20–30 lux could be healthier for children and adolescents because rapid and clear increase in melatonin concentration in blood seems to occur at night under such dim light, thus facilitating a smooth falling into night sleep.

High Brightness Neutron Source for Radiography. Final report

International Nuclear Information System (INIS)

Cremer, J.T.; Piestrup, Melvin A.; Gary, Charles K.; Harris, Jack L.; Williams, David J.; Jones, Glenn E.; Vainionpaa, J.H.; Fuller, Michael J.; Rothbart, George H.; Kwan, J.W.; Ludewigt, B.A.; Gough, R.A.; Reijonen, Jani; Leung, Ka-Ngo

2008-01-01

This research and development program was designed to improve nondestructive evaluation of large mechanical objects by providing both fast and thermal neutron sources for radiography. Neutron radiography permits inspection inside objects that x-rays cannot penetrate and permits imaging of corrosion and cracks in low-density materials. Discovering of fatigue cracks and corrosion in piping without the necessity of insulation removal is possible. Neutron radiography sources can provide for the nondestructive testing interests of commercial and military aircraft, public utilities and petrochemical organizations. Three neutron prototype neutron generators were designed and fabricated based on original research done at the Lawrence Berkeley National Laboratory (LBNL). The research and development of these generators was successfully continued by LBNL and Adelphi Technology Inc. under this STTR. The original design goals of high neutron yield and generator robustness have been achieved, using new technology developed under this grant. In one prototype generator, the fast neutron yield and brightness was roughly 10 times larger than previously marketed neutron generators using the same deuterium-deuterium reaction. In another generator, we integrate a moderator with a fast neutron source, resulting in a high brightness thermal neutron generator. The moderator acts as both conventional moderator and mechanical and electrical support structure for the generator and effectively mimics a nuclear reactor. In addition to the new prototype generators, an entirely new plasma ion source for neutron production was developed. First developed by LBNL, this source uses a spiral antenna to more efficiently couple the RF radiation into the plasma, reducing the required gas pressure so that the generator head can be completely sealed, permitting the possible use of tritium gas. This also permits the generator to use the deuterium-tritium reaction to produce 14-MeV neutrons with increases

Leveraging brightness from transportation lighting systems through light source color.

Science.gov (United States)

2013-11-01

Roadway transportation lighting is installed for multiple reasons including traffic safety and pedestrian : security. Judgments of pedestrian safety and security along roadways are not strictly correlated to : specified light levels, but the color of...

Variations in energy, flux, and brightness of pulsating aurora measured at high time resolution

Directory of Open Access Journals (Sweden)

H. Dahlgren

2017-03-01

Full Text Available High-resolution multispectral optical and incoherent scatter radar data are used to study the variability of pulsating aurora. Two events have been analysed, and the data combined with electron transport and ion chemistry modelling provide estimates of the energy and energy flux during both the ON and OFF periods of the pulsations. Both the energy and energy flux are found to be reduced during each OFF period compared with the ON period, and the estimates indicate that it is the number flux of foremost higher-energy electrons that is reduced. The energies are found never to drop below a few kilo-electronvolts during the OFF periods for these events. The high-resolution optical data show the occurrence of dips in brightness below the diffuse background level immediately after the ON period has ended. Each dip lasts for about a second, with a reduction in brightness of up to 70 % before the intensity increases to a steady background level again. A different kind of variation is also detected in the OFF period emissions during the second event, where a slower decrease in the background diffuse emission is seen with its brightness minimum just before the ON period, for a series of pulsations. Since the dips in the emission level during OFF are dependent on the switching between ON and OFF, this could indicate a common mechanism for the precipitation during the ON and OFF phases. A statistical analysis of brightness rise, fall, and ON times for the pulsations is also performed. It is found that the pulsations are often asymmetric, with either a slower increase of brightness or a slower fall.

Comparison of silicone and spin-on glass packaging materials for light-emitting diode encapsulation

Energy Technology Data Exchange (ETDEWEB)

Chang, Liann-Be; Pan, Ke-Wei; Yen, Chia-Yi [Department of Electronic Engineering and Green Technology Research Center, Chang Gung University, Taoyuan, Taiwan (China); Jeng, Ming-Jer, E-mail: mjjeng@mail.cgu.edu.tw [Department of Electronic Engineering and Green Technology Research Center, Chang Gung University, Taoyuan, Taiwan (China); Wu, Chun-Te; Hu, Sung-Cheng; Kuo, Yang-Kuao [Chemical Systems Research Division, Chung-Shan Institute of Science and Technology Armaments Bureau, MND, Taoyuan, Taiwan (China)

2014-11-03

Traditional white light light-emitting diode (LED) encapsulation is performed by mixed phosphors and silicone coating on LED die. However, this encapsulation with silicone coating incurs overheated temperatures and yellowing problem. Therefore, this work attempts to replace silicone paste by using spin-on-glass (SOG) materials. Experimental results indicate that although initial brightness of SOG-based packaging is lower than that of silicone packaging, its light attenuation is significantly lower than that of silicone for a long lighting time. After the LED power is turned on for 12 h, the brightness of LED with silicone and SOG material packaging decreases from 84 to 48 lm and 73 to 59 lm, respectively. Therefore, SOG material provides an alternative packaging solution for high power LED lighting applications. - Highlights: • Spin-on-glass (SOG) material was used to replace silicone coating for LED packaging. • Initial brightness of SOG packaging is lower than that of silicone packaging. • Over time, light attenuation in SOG is much lower than that in silicone. • Color rendering index and brightness of LED packaging was optimized by Taguchi method.

A high brightness source for nano-probe secondary ion mass spectrometry

Energy Technology Data Exchange (ETDEWEB)

Smith, N.S. [Oregon Physics LLC, 2704 SE 39th Loop, Suite 109, Hillsboro, OR 97123 (United States)], E-mail: n.smith@oregon-physics.com; Tesch, P.P.; Martin, N.P.; Kinion, D.E. [Oregon Physics LLC, 2704 SE 39th Loop, Suite 109, Hillsboro, OR 97123 (United States)

2008-12-15

The two most prevalent ion source technologies in the field of surface analysis and surface machining are the Duoplasmatron and the liquid metal ion source (LMIS). There have been many efforts in this area of research to develop an alternative source [; N.S. Smith, W.P. Skoczylas, S.M. Kellogg, D.E. Kinion, P.P. Tesch, O. Sutherland, A. Aanesland, R.W. Boswell, J. Vac. Sci. Technol. B 24 (6) (2006) 2902-2906] with the brightness of a LMIS and yet the ability to produce secondary ion yield enhancing species such as oxygen. However, to date a viable alternative has not been realized. The high brightness and small virtual source size of the LMIS are advantageous for forming high resolution probes but a significant disadvantage when beam currents in excess of 100 nA are required, due to the effects of spherical aberration from the optical column. At these higher currents a source with a high angular intensity is optimal and in fact the relatively moderate brightness of today's plasma ion sources prevail in this operating regime. Both the LMIS and Duoplasmatron suffer from a large axial energy spread resulting in further limitations when forming focused beams at the chromatic limit where the figure-of-merit is inversely proportional to the square of the energy spread. Also, both of these ion sources operate with a very limited range of ion species. This article reviews some of the latest developments and some future potential in this area of instrument development. Here we present an approach to source development that could lead to oxygen ion beam SIMS imaging with 10 nm resolution, using a 'broad area' RF gas phase ion source.

Criteria for emittance compensation in high-brightness photoinjectors

Directory of Open Access Journals (Sweden)

Chun-xi Wang

2007-10-01

Full Text Available A critical process in high-brightness photoinjectors is emittance compensation, which brings under control the correlated transverse emittance growth due to the linear space-charge force. Although emittance compensation has been used and studied for almost two decades, the exact criteria to achieve emittance compensation is not as clear as it should be. In this paper, a perturbative analysis of slice envelopes and emittance evolution close to any reference envelope is developed, via which space-charge and chromatic effects are investigated. A new criterion for emittance compensation is found, which is complementary to the well-known matching condition for the invariant envelope and agrees very well with simulations.

High spatial resolution and high brightness ion beam probe for in-situ elemental and isotopic analysis

Science.gov (United States)

Long, Tao; Clement, Stephen W. J.; Bao, Zemin; Wang, Peizhi; Tian, Di; Liu, Dunyi

2018-03-01

A high spatial resolution and high brightness ion beam from a cold cathode duoplasmatron source and primary ion optics are presented and applied to in-situ analysis of micro-scale geological material with complex structural and chemical features. The magnetic field in the source as well as the influence of relative permeability of magnetic materials on source performance was simulated using COMSOL to confirm the magnetic field strength of the source. Based on SIMION simulation, a high brightness and high spatial resolution negative ion optical system has been developed to achieve Critical (Gaussian) illumination mode. The ion source and primary column are installed on a new Time-of-Flight secondary ion mass spectrometer for analysis of geological samples. The diameter of the ion beam was measured by the knife-edge method and a scanning electron microscope (SEM). Results show that an O2- beam of ca. 5 μm diameter with a beam intensity of ∼5 nA and an O- beam of ca. 5 μm diameter with a beam intensity of ∼50 nA were obtained, respectively. This design will open new possibilities for in-situ elemental and isotopic analysis in geological studies.

An optically stabilized fast-switching light emitting diode as a light source for functional neuroimaging.

Directory of Open Access Journals (Sweden)

Daniel A Wagenaar

Full Text Available Neuroscience research increasingly relies on optical methods for evoking neuronal activity as well as for measuring it, making bright and stable light sources critical building blocks of modern experimental setups. This paper presents a method to control the brightness of a high-power light emitting diode (LED light source to an unprecedented level of stability. By continuously monitoring the actual light output of the LED with a photodiode and feeding the result back to the LED's driver by way of a proportional-integral controller, drift was reduced to as little as 0.007% per hour over a 12-h period, and short-term fluctuations to 0.005% root-mean-square over 10 seconds. The LED can be switched on and off completely within 100 μs, a feature that is crucial when visual stimuli and light for optical recording need to be interleaved to obtain artifact-free recordings. The utility of the system is demonstrated by recording visual responses in the central nervous system of the medicinal leech Hirudo verbana using voltage-sensitive dyes.

[The Performance Analysis for Lighting Sources in Highway Tunnel Based on Visual Function].

Science.gov (United States)

Yang, Yong; Han, Wen-yuan; Yan, Ming; Jiang, Hai-feng; Zhu, Li-wei

2015-10-01

Under the condition of mesopic vision, the spectral luminous efficiency function is shown as a series of curves. Its peak wavelength and intensity are affected by light spectrum, background brightness and other aspects. The impact of light source to lighting visibility could not be carried out via a single optical parametric characterization. The reaction time of visual cognition is regard as evaluating indexes in this experiment. Under the condition of different speed and luminous environment, testing visual cognition based on vision function method. The light sources include high pressure sodium, electrodeless fluorescent lamp and white LED with three kinds of color temperature (the range of color temperature is from 1 958 to 5 537 K). The background brightness value is used for basic section of highway tunnel illumination and general outdoor illumination, its range is between 1 and 5 cd x m(-)2. All values are in the scope of mesopic vision. Test results show that: under the same condition of speed and luminance, the reaction time of visual cognition that corresponding to high color temperature of light source is shorter than it corresponding to low color temperature; the reaction time corresponding to visual target in high speed is shorter than it in low speed. At the end moment, however, the visual angle of target in observer's visual field that corresponding to low speed was larger than it corresponding to high speed. Based on MOVE model, calculating the equivalent luminance of human mesopic vision, which is on condition of different emission spectrum and background brightness that formed by test lighting sources. Compared with photopic vision result, the standard deviation (CV) of time-reaction curve corresponding to equivalent brightness of mesopic vision is smaller. Under the condition of mesopic vision, the discrepancy between equivalent brightness of different lighting source and photopic vision, that is one of the main reasons for causing the

Analysis of a high brightness photo electron beam with self field and wake field effects

International Nuclear Information System (INIS)

Parsa, Z.

1991-01-01

High brightness sources are the basic ingredients in the new accelerator developments such as Free-Electron Laser experiments. The effects of the interactions between the highly charged particles and the fields in the accelerating structure, e.g. R.F., Space charge and Wake fields can be detrimental to the beam and the experiments. We present and discuss the formulation used, some simulation and results for the Brookhaven National Laboratory high brightness beam that illustrates effects of the accelerating field, space charge forces (e.g. due to self field of the bunch), and the wake field (e.g. arising from the interaction of the cavity surface and the self field of the bunch)

Lighting Assessment in Knitting Workshop in Yazd

Directory of Open Access Journals (Sweden)

A Barkhordari

2016-01-01

Full Text Available Introduction: The sense of sight is one of the most vital human senses and help the environment gets most of its information. Whatever one's job is more subtle, more work will be given brightness. Good lighting, increase work efficiency and general physiological effects on people's moods. The relationship between low and high frequency illumination accidents there Methods: This study was conducted in 10 workshops in Yazd home knitting. Due to maximize natural lighting measurements in June and November this year took place in cloudy days. Thus, in both seasons overall lighting, natural and artificial, were evaluated. That, in order to measure all the natural light, artificial light sources (lamps and the measurements were off by clarifying re-lamp, the overall lighting (natural and artificial were measured. In order to measure the general lighting provided by the Illuminating Engineering society and stop the pattern surfaces were used. The workshops with less than standard lighting conditions were identified and interventions to improve the brightness of the workshops were measured again. Results: Average, minimum and maximum overall brightness of spring workshops 4 and 6 respectively, with values of 67/278 and 53/452 is a luxury. Workshops values 5 and 2 47/184 and 43/218 minimum and maximum luxury in order to be daylight in spring. Conclusions: The majority of the studied weaving Workshops lighting was good, with measures such as proper installation and periodic cleaning and dust lamps, replacement lamps burned by use of fluorescent ambient lighting conditions can be improved.

Continued advances in high brightness fiber-coupled laser modules for efficient pumping of fiber and solid-state lasers

Science.gov (United States)

Hemenway, M.; Chen, Z.; Urbanek, W.; Dawson, D.; Bao, L.; Kanskar, M.; DeVito, M.; Martinsen, R.

2018-02-01

Both the fibber laser and diode-pumped solid-state laser market continue to drive advances in pump diode module brightness. We report on the continued progress by nLIGHT to develop and deliver the highest brightness diode-laser pumps using single-emitter technology. Continued advances in multimode laser diode technology [13] and fiber-coupling techniques have enabled higher emitter counts in the element packages, enabling us to demonstrate 305 W into 105 μm - 0.16 NA. This brightness improvement is achieved by leveraging our prior-reported package re-optimization, allowing an increase in the emitter count from two rows of nine emitters to two rows of twelve emitters. Leveraging the two rows off twelve emitter architecture,, product development has commenced on a 400 W into 200 μm - 00.16 NA package. Additionally, the advances in pump technology intended for CW Yb-doped fiber laser pumping has been leveraged to develop the highest brightness 793 nm pump modules for 2 μm Thulium fiber laser pumping, generating 150 W into 200 μm - 0.18 NA and 100 W into 105 μm - 0.15 NA. Lastly, renewed interest in direct diode materials processing led us to experiment with wavelength multiplexing our existing state of the art 200 W, 105 μm - 00.15 NA package into a combined output of 395 WW into 105 μm - 0.16 NA.

Stable high brightness radio frequency driven micro-discharge lamps at 193 (ArF*) and 157 nm ( F2*)

International Nuclear Information System (INIS)

Salvermoser, M; Murnick, D E

2004-01-01

A stable discharge between two pin electrodes separated by several hundred micrometres in a high pressure rare gas (∼900 mbar) halogen (∼1 mbar) mixture is shown to yield continuous wave (CW) ultra violet (UV) and vacuum UV light sources. Lamps operating at 193 (ArF*) and 157 nm F 2 *) have been demonstrated. Total CW output power in the UV was measured to be 30 for ArF* and 20 mW for F 2 *. The brightness of the light sources is estimated to be of the order of several W cm -2 sr -1 . With direct current excitation, electrode lifetimes are limited to a few minutes due to fluorine salt deposits. However, using a radio frequency (RF) field to drive the discharge, the lifetime of the lamps increased to hundreds of hours. A one-dimensional model of the RF micro-discharge explaining the increase in electrode lifetime is presented. The technology described can be adapted to many other wavelengths and promises even higher powers in future

Circadian phase-shifting effects of a laboratory environment: a clinical trial with bright and dim light

Directory of Open Access Journals (Sweden)

Elliott Jeffrey A

2005-09-01

Full Text Available Abstract Background Our aims were to examine the influence of different bright light schedules on mood, sleep, and circadian organization in older adults (n = 60, ages 60–79 years with insomnia and/or depression, contrasting with responses of young, healthy controls (n = 30, ages 20–40 years. Methods Volunteers were assessed for one week in their home environments. Urine was collected over two 24-hour periods to establish baseline acrophase of 6-sulphatoxymelatonin (aMT6s excretion. Immediately following home recording, volunteers spent five nights and four days in the laboratory. Sleep periods were fixed at eight hours in darkness, consistent with the volunteers' usual sleep periods. Volunteers were randomly assigned to one of three light treatments (four hours per day within the wake period: (A two hours of 3,000 lux at 1–3 hours and 13–15 hours after arising; (B four hours of 3,000 lux at 6–10 hours after arising; (C four hours of dim placebo light at 6–10 hours after arising. Lighting was 50 lux during the remainder of wakefulness. The resulting aMT6s acrophase was determined during the final 30 hours in the laboratory. Results Neither mood nor total melatonin excretion differed significantly by treatment. For the three light treatments, significant and similar phase-response plots were found, indicating that the shift in aMT6s acrophase was dependent upon the circadian time of treatment. The changes in circadian timing were not significantly correlated to changes in sleep or mood. Conclusion The trial failed to demonstrate photoperiodic effects. The results suggest that even low levels of illumination and/or fixed timing of behavior had significant phase-shifting effects.

Highly efficient blue organic light emitting device using indium-free transparent anode Ga:ZnO with scalability for large area coating

International Nuclear Information System (INIS)

Wang Liang; Matson, Dean W.; Polikarpov, Evgueni; Swensen, James S.; Bonham, Charles C.; Cosimbescu, Lelia; Gaspar, Daniel J.; Padmaperuma, Asanga B.; Berry, Joseph J.; Ginley, David S.

2010-01-01

Organic light emitting devices have been achieved with an indium-free transparent anode, Ga doped ZnO (GZO). A large area coating technique was used (RF magnetron sputtering) to deposit the GZO films onto glass. The respective organic light emitting devices exhibited an operational voltage of 3.7 V, an external quantum efficiency of 17%, and a power efficiency of 39 lm/W at a current density of 1 mA/cm 2 . These parameters are well within acceptable standards for blue OLEDs to generate a white light with high enough brightness for general lighting applications. It is expected that high-efficiency, long-lifetime, large area, and cost-effective white OLEDs can be made with these indium-free anode materials.

Characterizing bars in low surface brightness disc galaxies

Science.gov (United States)

Peters, Wesley; Kuzio de Naray, Rachel

2018-05-01

In this paper, we use B-band, I-band, and 3.6 μm azimuthal light profiles of four low surface brightness galaxies (LSBs; UGC 628, F568-1, F568-3, F563-V2) to characterize three bar parameters: length, strength, and corotation radius. We employ three techniques to measure the radius of the bars, including a new method using the azimuthal light profiles. We find comparable bar radii between the I-band and 3.6 μm for all four galaxies when using our azimuthal light profile method, and that our bar lengths are comparable to those in high surface brightness galaxies (HSBs). In addition, we find the bar strengths for our galaxies to be smaller than those for HSBs. Finally, we use Fourier transforms of the B-band, I-band, and 3.6 μm images to characterize the bars as either `fast' or `slow' by measuring the corotation radius via phase profiles. When using the B- and I-band phase crossings, we find three of our galaxies have faster than expected relative bar pattern speeds for galaxies expected to be embedded in centrally dense cold dark matter haloes. When using the B-band and 3.6 μm phase crossings, we find more ambiguous results, although the relative bar pattern speeds are still faster than expected. Since we find a very slow bar in F563-V2, we are confident that we are able to differentiate between fast and slow bars. Finally, we find no relation between bar strength and relative bar pattern speed when comparing our LSBs to HSBs.

The bright-bright and bright-dark mode coupling-based planar metamaterial for plasmonic EIT-like effect

Science.gov (United States)

Yu, Wei; Meng, Hongyun; Chen, Zhangjie; Li, Xianping; Zhang, Xing; Wang, Faqiang; Wei, Zhongchao; Tan, Chunhua; Huang, Xuguang; Li, Shuti

2018-05-01

In this paper, we propose a novel planar metamaterial structure for the electromagnetically induced transparency (EIT)-like effect, which consists of a split-ring resonator (SRR) and a pair of metal strips. The simulated results indicate that a single transparency window can be realized in the symmetry situation, which originates from the bright-bright mode coupling. Further, a dual-band EIT-like effect can be achieved in the asymmetry situation, which is due to the bright-bright mode coupling and bright-dark mode coupling, respectively. Different EIT-like effect can be simultaneously achieved in the proposed structure with the different situations. It is of certain significance for the study of EIT-like effect.

Sky brightness and twilight measurements at Jogyakarta city, Indonesia

International Nuclear Information System (INIS)

Herdiwijaya, Dhani

2016-01-01

The sky brightness measurements were performed using a portable photometer. A pocket-sized and low-cost photometer has 20 degree area measurement, and spectral ranges between 320-720 nm with output directly in magnitudes per arc second square (mass) unit. The sky brightness with 3 seconds temporal resolutions was recorded at Jogyakarta city (110° 25’ E; 70° 52’ S; elevation 100 m) within 136 days in years from 2014 to 2016. The darkest night could reach 22.61 mpass only in several seconds, with mean value 18.8±0.7 mpass and temperature variation 23.1±1.2 C. The difference of mean sky brightness between before and after midnight was about -0.76 mpass or 2.0 times brighter. Moreover, the sky brightness and temperature fluctuations were more stable in after midnight than in before midnight. It is suggested that city light pollution affects those variations, and subsequently duration of twilight. By comparing twilight brightness for several places, we also suggest a 17° solar dip or about 66 minutes before sunrise for new time of Fajr prayer. (paper)

The JLab high power ERL light source

International Nuclear Information System (INIS)

Neil, G.R.; Behre, C.; Benson, S.V.

2006-01-01

A new THz/IR/UV photon source at Jefferson Lab is the first of a new generation of light sources based on an Energy-Recovered (superconducting) Linac (ERL). The machine has a 160MeV electron beam and an average current of 10mA in 75MHz repetition rate hundred femtosecond bunches. These electron bunches pass through a magnetic chicane and therefore emit synchrotron radiation. For wavelengths longer than the electron bunch the electrons radiate coherently a broadband THz ∼ half cycle pulse whose average brightness is >5 orders of magnitude higher than synchrotron IR sources. Previous measurements showed 20W of average power extracted [Carr, et al., Nature 420 (2002) 153]. The new facility offers simultaneous synchrotron light from the visible through the FIR along with broadband THz production of 100fs pulses with >200W of average power. The FELs also provide record-breaking laser power [Neil, et al., Phys. Rev. Lett. 84 (2000) 662]: up to 10kW of average power in the IR from 1 to 14μm in 400fs pulses at up to 74.85MHz repetition rates and soon will produce similar pulses of 300-1000nm light at up to 3kW of average power from the UV FEL. These ultrashort pulses are ideal for maximizing the interaction with material surfaces. The optical beams are Gaussian with nearly perfect beam quality. See www.jlab.org/FEL for details of the operating characteristics; a wide variety of pulse train configurations are feasible from 10ms long at high repetition rates to continuous operation. The THz and IR system has been commissioned. The UV system is to follow in 2005. The light is transported to user laboratories for basic and applied research. Additional lasers synchronized to the FEL are also available. Past activities have included production of carbon nanotubes, studies of vibrational relaxation of interstitial hydrogen in silicon, pulsed laser deposition and ablation, nitriding of metals, and energy flow in proteins. This paper will present the status of the system and

The JLab high power ERL light source

Energy Technology Data Exchange (ETDEWEB)

G.R. Neil; C. Behre; S.V. Benson; M. Bevins; G. Biallas; J. Boyce; J. Coleman; L.A. Dillon-Townes; D. Douglas; H.F. Dylla; R. Evans; A. Grippo; D. Gruber; J. Gubeli; D. Hardy; C. Hernandez-Garcia; K. Jordan; M.J. Kelley; L. Merminga; J. Mammosser; W. Moore; N. Nishimori; E. Pozdeyev; J. Preble; R. Rimmer; Michelle D. Shinn; T. Siggins; C. Tennant; R. Walker; G.P. Williams and S. Zhang

2005-03-19

A new THz/IR/UV photon source at Jefferson Lab is the first of a new generation of light sources based on an Energy-Recovered, (superconducting) Linac (ERL). The machine has a 160 MeV electron beam and an average current of 10 mA in 75 MHz repetition rate hundred femtosecond bunches. These electron bunches pass through a magnetic chicane and therefore emit synchrotron radiation. For wavelengths longer than the electron bunch the electrons radiate coherently a broadband THz {approx} half cycle pulse whose average brightness is > 5 orders of magnitude higher than synchrotron IR sources. Previous measurements showed 20 W of average power extracted[1]. The new facility offers simultaneous synchrotron light from the visible through the FIR along with broadband THz production of 100 fs pulses with >200 W of average power. The FELs also provide record-breaking laser power [2]: up to 10 kW of average power in the IR from 1 to 14 microns in 400 fs pulses at up to 74.85 MHz repetition rates and soon will produce similar pulses of 300-1000 nm light at up to 3 kW of average power from the UV FEL. These ultrashort pulses are ideal for maximizing the interaction with material surfaces. The optical beams are Gaussian with nearly perfect beam quality. See www.jlab.org/FEL for details of the operating characteristics; a wide variety of pulse train configurations are feasible from 10 microseconds long at high repetition rates to continuous operation. The THz and IR system has been commissioned. The UV system is to follow in 2005. The light is transported to user laboratories for basic and applied research. Additional lasers synchronized to the FEL are also available. Past activities have included production of carbon nanotubes, studies of vibrational relaxation of interstitial hydrogen in silicon, pulsed laser deposition and ablation, nitriding of metals, and energy flow in proteins. This paper will present the status of the system and discuss some of the discoveries we have made

Application of Cherenkov light observation to reactor measurements (2). Design and trial fabrication of Cherenkov light estimation system

International Nuclear Information System (INIS)

Yamamoto, Keiichi; Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Hayashi, Takayasu; Kosuge, Fumiaki; Sano, Tadafumi

2015-11-01

Development of the reactor measurement system was started to obtain the real-time in-core nuclear and thermal information, where the quantitative measurement of brightness of Cherenkov light was investigated. This report summarized the results of design and trial fabrication of the Cherenkov light estimation system from thermal power evaluation from Cherenkov light image emitted from the fuel elements. The developed Cherenkov light estimation system was verified with the Cherenkov light image emitted from the fuels in the core of Kyoto University Research Reactor (KUR). From the results, the thermal power of the fuel elements evaluated from the brightness of the Cherenkov light observed by a CCD camera was almost the same as that of thermal power calculated from SRAC code. On the other hand, the evaluation values of some fuel elements were different from the calculation values. This, it is necessary to improve the observation method of Cherenkov light in the reactor and the evaluation method of the brightness of Cherenkov light. (author)

Advanced high brightness ion rf accelerator applications in the nuclear energy

International Nuclear Information System (INIS)

Jameson, R.A.

1991-01-01

The capability of modern rf linear accelerators to provide intense high quality beams of protons, deuterons, or heavier ions is opening new possibilities for transmuting existing nuclear wastes, for generating electricity from readily available fuels with minimal residual wastes, for building intense neutron sources for materials research, for inertial confinement fusion using heavy ions, and for other new applications. These are briefly described, couched in a perspective of the advances in the understanding of the high brightness beams that has enabled these new programs. 32 refs., 2 figs

High power, high brightness electron beam generation in a pulse-line driven pseudospark discharge

International Nuclear Information System (INIS)

Destler, W.W.; Segalov, Z.; Rodgers, J.; Ramaswamy, K.; Reiser, M.

1993-01-01

High brightness (∼10 10 A/m 2 rad 2 ), high power density (∼10 10 W/cm 2 ) electron beams have been generated by the mating of a hollow-cathode discharge device operating in the pseudospark regime to the output of a high power pulse line accelerator. Very small diameter (∼1 mm) electron beams with currents in the range 500--1000 A and energies in the range 150--300 keV have been generated with effective emittances estimated to be at or below 170 mm mrad. Such emittances are comparable to those achieved in conventional electron beam sources at current densities several orders of magnitude lower than those observed in these experiments

State-Of High Brightness RF Photo-Injector Design

Science.gov (United States)

Ferrario, Massimo; Clendenin, Jym; Palmer, Dennis; Rosenzweig, James; Serafini, Luca

2000-04-01

The art of designing optimized high brightness electron RF Photo-Injectors has moved in the last decade from a cut and try procedure, guided by experimental experience and time consuming particle tracking simulations, up to a fast parameter space scanning, guided by recent analytical results and a fast running semi-analytical code, so to reach the optimum operating point which corresponds to maximum beam brightness. Scaling laws and the theory of invariant envelope provide to the designers excellent tools for a first parameters choice and the code HOMDYN, based on a multi-slice envelope description of the beam dynamics, is tailored to describe the space charge dominated dynamics of laminar beams in presence of time dependent space charge forces, giving rise to a very fast modeling capability for photo-injectors design. We report in this talk the results of a recent beam dynamics study, motivated by the need to redesign the LCLS photoinjector. During this work a new effective working point for a split RF photoinjector has been discovered by means of the previous mentioned approach. By a proper choice of rf gun and solenoid parameters, the emittance evolution shows a double minimum behavior in the drifting region. If the booster is located where the relative emittance maximum and the envelope waist occur, the second emittance minimum can be shifted at the booster exit and frozen at a very low level (0.3 mm-mrad for a 1 nC flat top bunch), to the extent that the invariant envelope matching conditions are satisfied.

The limit values for brightness and contrast adjustment in digital panoramic radiography

Science.gov (United States)

Zahra, A. T.; Syahraini, S. I.; Kiswanjaya, B.; Ustriyana, P.

2017-08-01

There is an overall lack of studies about digital panoramic radiography. The application of image enhancement techniques is still being done based on the operator’s preferences, since there is no objective limitation. The aim is to evaluate the limit values of the brightness and contrast adjustment in digital panoramic radiography. Digital panoramic radiographs were divided into three groups (dark, medium, and light), and the contrast and brightness adjustments were done using Digora for Windows. The static evaluations were done using three criteria: 1 if the image had lower quality, 2 if there was no difference and 3 if the image had better quality. The radiographic changes differed in each group depending on the initial imaging conditions. The brightness adjustment limit values in the dark and medium groups were -10 and +20, respectively, and -20 and +10 in the light group. The contrast adjustment limit values in all of the groups were -10 and +10.

High Efficiency, Illumination Quality OLEDs for Lighting

Energy Technology Data Exchange (ETDEWEB)

Joseph Shiang; James Cella; Kelly Chichak; Anil Duggal; Kevin Janora; Chris Heller; Gautam Parthasarathy; Jeffery Youmans; Joseph Shiang

2008-03-31

The goal of the program was to demonstrate a 45 lumen per watt white light device based upon the use of multiple emission colors through the use of solution processing. This performance level is a dramatic extension of the team's previous 15 LPW large area illumination device. The fundamental material system was based upon commercial polymer materials. The team was largely able to achieve these goals, and was able to deliver to DOE a 90 lumen illumination source that had an average performance of 34 LPW a 1000 cd/m{sup 2} with peak performances near 40LPW. The average color temperature is 3200K and the calculated CRI 85. The device operated at a brightness of approximately 1000cd/m{sup 2}. The use of multiple emission colors particularly red and blue, provided additional degrees of design flexibility in achieving white light, but also required the use of a multilayered structure to separate the different recombination zones and prevent interconversion of blue emission to red emission. The use of commercial materials had the advantage that improvements by the chemical manufacturers in charge transport efficiency, operating life and material purity could be rapidly incorporated without the expenditure of additional effort. The program was designed to take maximum advantage of the known characteristics of these material and proceeded in seven steps. (1) Identify the most promising materials, (2) assemble them into multi-layer structures to control excitation and transport within the OLED, (3) identify materials development needs that would optimize performance within multilayer structures, (4) build a prototype that demonstrates the potential entitlement of the novel multilayer OLED architecture (5) integrate all of the developments to find the single best materials set to implement the novel multilayer architecture, (6) further optimize the best materials set, (7) make a large area high illumination quality white OLED. A photo of the final deliverable is shown

Bright Stuff on Ceres = Sulfates and Carbonates on CI Chondrites

Science.gov (United States)

Zolensky, Michael; Chan, Queenie H. S.; Gounelle, Matthieu; Fries, Marc

2016-01-01

Recent reports of the DAWN spacecraft's observations of the surface of Ceres indicate that there are bright areas, which can be explained by large amounts of the Mg sulfate hexahydrate (MgSO4•6(H2O)), although the identification appears tenuous. There are preliminary indications that water is being evolved from these bright areas, and some have inferred that these might be sites of contemporary hydro-volcanism. A heat source for such modern activity is not obvious, given the small size of Ceres, lack of any tidal forces from nearby giant planets, probable age and presumed bulk composition. We contend that observations of chondritic materials in the lab shed light on the nature of the bright spots on Ceres

Enhancing light emission in flexible AC electroluminescent devices by tetrapod-like zinc oxide whiskers.

Science.gov (United States)

Wen, Li; Liu, Nishuang; Wang, Siliang; Zhang, Hui; Zhao, Wanqiu; Yang, Zhichun; Wang, Yumei; Su, Jun; Li, Luying; Long, Fei; Zou, Zhengguang; Gao, Yihua

2016-10-03

Flexible alternating current electroluminescent devices (ACEL) are more and more popular and widely used in liquid-crystal display back-lighting, large-scale architectural and decorative lighting due to their uniform light emission, low power consumption and high resolution. However, presently how to acquire high brightness under a certain voltage are confronted with challenges. Here, we demonstrate an electroluminescence (EL) enhancing strategy that tetrapod-like ZnO whiskers (T-ZnOw) are added into the bottom electrode of carbon nanotubes (CNTs) instead of phosphor layer in flexible ACEL devices emitting blue, green and orange lights, and the brightness is greatly enhanced due to the coupling between the T-ZnOw and ZnS phosphor dispersed in the flexible polydimethylsiloxane (PDMS) layer. This strategy provides a new routine for the development of high performance, flexible and large-area ACEL devices.

Morning Versus Evening Bright Light Treatment at Home to Improve Function and Pain Sensitivity for Women with Fibromyalgia: A Pilot Study.

Science.gov (United States)

Burgess, Helen J; Park, Margaret; Ong, Jason C; Shakoor, Najia; Williams, David A; Burns, John

2017-01-01

To test the feasibility, acceptability, and effects of a home-based morning versus evening bright light treatment on function and pain sensitivity in women with fibromyalgia. A single blind randomized study with two treatment arms: 6 days of a 1 hour morning light treatment or 6 days of a 1 hour evening light treatment. Function, pain sensitivity, and circadian timing were assessed before and after treatment. Participants slept at home, except for two nights in Sleep Center. Ten women meeting the American College of Rheumatology's diagnostic criteria for fibromyalgia, including normal blood test results. Self-reported function was assessed with the Fibromyalgia Impact Questionnaire (FIQ). Pain sensitivity was assessed using a heat stimulus that gave measures of threshold and tolerance. Circadian timing was assessed with the dim light melatonin onset. Both morning and evening light treatments led to improvements in function and pain sensitivity. However, only the morning light treatment led to a clinically meaningful improvement in function (>14% reduction from baseline FIQ) and morning light significantly increased pain threshold more than evening light ( P  treatment appears to be a feasible and acceptable adjunctive treatment to women with fibromyalgia. Those who undergo morning light treatment may show improvements in function and pain sensitivity. Advances in circadian timing may be one mechanism by which morning light improves pain sensitivity. Findings can inform the design of a randomized controlled trial. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

The Advanced Light Source Upgrade

International Nuclear Information System (INIS)

Chemla, Daniel S.; Feinberg, Benjamin; Hussain, Zahid; Krebs, Gary F.; Padmore, Howard A.; Robin, David S.; Robinson, Arthur L.; Smith, Neville V.

2003-01-01

The ALS, a third-generation synchrotron light source at Berkeley Lab, has been operating for almost a decade and is generating forefront science by exploiting the high brightness of a third-generation source in three areas: (1) high resolving power for spectroscopy; (2) high spatial resolution for microscopy and spectromicroscopy; and (3) high coherence for experiments such as speckle. However, the ALS was one of the first third-generation machines to be designed, and accelerator and insertion-device technology have significantly changed since its conception. As a result, its performance will inevitably be outstripped by newer, more advanced sources. To remain competitive and then set a new standard, the performance of the ALS, in particular its brightness, must be enhanced. Substantial improvements in brightness and current have always been feasible in principle, but they incur the penalty of a much reduced lifetime, which is totally unacceptable to our users. Significant brightness improvements can be realized in the core soft x-ray region by going to top-off operation, where injection would be quasi-continuous and the lifetime objections disappear. In top-off mode with higher average current, a reduced vertical emittance and beta function, and small-gap permanent-magnet or superconducting insertion devices, one to two orders of magnitude improvement in brightness can be had in the soft x-ray range. These improvements also extend the high energy range of the undulator radiation beyond the current limit of 2000 eV. Descriptions of the upgrade and the important new science achievable are presented

Theoretical approaches to lightness and perception.

Science.gov (United States)

Gilchrist, Alan

2015-01-01

Theories of lightness, like theories of perception in general, can be categorized as high-level, low-level, and mid-level. However, I will argue that in practice there are only two categories: one-stage mid-level theories, and two-stage low-high theories. Low-level theories usually include a high-level component and high-level theories include a low-level component, the distinction being mainly one of emphasis. Two-stage theories are the modern incarnation of the persistent sensation/perception dichotomy according to which an early experience of raw sensations, faithful to the proximal stimulus, is followed by a process of cognitive interpretation, typically based on past experience. Like phlogiston or the ether, raw sensations seem like they must exist, but there is no clear evidence for them. Proximal stimulus matches are postperceptual, not read off an early sensory stage. Visual angle matches are achieved by a cognitive process of flattening the visual world. Likewise, brightness (luminance) matches depend on a cognitive process of flattening the illumination. Brightness is not the input to lightness; brightness is slower than lightness. Evidence for an early (perception, the many claims tend to fall apart upon close inspection of the evidence. Much of the evidence for the current revival of the 'new look' is probably better explained by (1) a natural desire of (some) subjects to please the experimenter, and (2) the ease of intuiting an experimental hypothesis. High-level theories of lightness are overkill. The visual system does not need to know the amount of illumination, merely which surfaces share the same illumination. This leaves mid-level theories derived from the gestalt school. Here the debate seems to revolve around layer models and framework models. Layer models fit our visual experience of a pattern of illumination projected onto a pattern of reflectance, while framework models provide a better account of illusions and failures of constancy

Optical Sky Brightness and Transparency during the Winter Season at Dome A Antarctica from the Gattini-All-Sky Camera

Science.gov (United States)

Yang, Yi; Moore, Anna M.; Krisciunas, Kevin; Wang, Lifan; Ashley, Michael C. B.; Fu, Jianning; Brown, Peter J.; Cui, Xiangqun; Feng, Long-Long; Gong, Xuefei; Hu, Zhongwen; Lawrence, Jon S.; Luong-Van, Daniel; Riddle, Reed L.; Shang, Zhaohui; Sims, Geoff; Storey, John W. V.; Suntzeff, Nicholas B.; Tothill, Nick; Travouillon, Tony; Yang, Huigen; Yang, Ji; Zhou, Xu; Zhu, Zhenxi

2017-07-01

The summit of the Antarctic plateau, Dome A, is proving to be an excellent site for optical, near-infrared, and terahertz astronomical observations. Gattini is a wide-field camera installed on the PLATO instrument module as part of the Chinese-led traverse to Dome A in 2009 January. We present here the measurements of sky brightness with the Gattini ultra-large field of view (90^\\circ × 90^\\circ ) in the photometric B-, V-, and R-bands; cloud cover statistics measured during the 2009 winter season; and an estimate of the sky transparency. A cumulative probability distribution indicates that the darkest 10% of the nights at Dome A have sky brightness of S B = 22.98, S V = 21.86, and S R = 21.68 mag arcsec-2. These values were obtained during the year 2009 with minimum aurora, and they are comparable to the faintest sky brightness at Maunakea and the best sites of northern Chile. Since every filter includes strong auroral lines that effectively contaminate the sky brightness measurements, for instruments working around the auroral lines, either with custom filters or with high spectral resolution instruments, these values could be easily obtained on a more routine basis. In addition, we present example light curves for bright targets to emphasize the unprecedented observational window function available from this ground-based site. These light curves will be published in a future paper.

Composition-Dependent Energy Splitting between Bright and Dark Excitons in Lead Halide Perovskite Nanocrystals.

Science.gov (United States)

Chen, Lan; Li, Bin; Zhang, Chunfeng; Huang, Xinyu; Wang, Xiaoyong; Xiao, Min

2018-03-14

Perovskite semiconductor nanocrystals with different compositions have shown promise for applications in light-emitting devices. Dark excitonic states may suppress light emission from such nanocrystals by providing an additional nonradiative recombination channel. Here, we study the composition dependence of dark exciton dynamics in nanocrystals of lead halides by time-resolved photoluminescence spectroscopy at cryogenic temperatures. The presence of a spin-related dark state is revealed by magneto-optical spectroscopy. The energy splitting between bright and dark states is found to be highly sensitive to both halide elements and organic cations, which is explained by considering the effects of size confinement and charge screening, respectively, on the exchange interaction. These findings suggest the possibility of manipulating dark exciton dynamics in perovskite semiconductor nanocrystals by composition engineering, which will be instrumental in the design of highly efficient light-emitting devices.

Three-Port dc-dc Conversion in Light-to-Light Systems

DEFF Research Database (Denmark)

Mira Albert, Maria del Carmen

conversion efficiency under low irradiation conditions. This work is part of a Ph.D. research project to study the feasibility of implementing three-port converter (TPC) topologies in solar powered LED, light-to-light (LtL) systems. After the introduction in Chapter 1, an overview of the state-of-the art...... conventional light sources based on heated filaments (incandescent and halogen) and gas discharge (fluorescent, sodium, etc). The rapid development of this technology makes it possible to replace the conventional technologies towards high brightness LED lighting systems. The combination of these technologies......—solar cells, energy storage elements and LEDs—in a stand-alone solar powered LED system, can provide light where otherwise it would be cumbersome; in rural areas, where cabling can be challenging and expensive, and also in the urban environment, where the cost of digging and construction is very expensive...

Shedding light on emotional perception: Interaction of brightness and semantic content in extrastriate visual cortex.

Science.gov (United States)

Schettino, Antonio; Keil, Andreas; Porcu, Emanuele; Müller, Matthias M

2016-06-01

The rapid extraction of affective cues from the visual environment is crucial for flexible behavior. Previous studies have reported emotion-dependent amplitude modulations of two event-related potential (ERP) components - the N1 and EPN - reflecting sensory gain control mechanisms in extrastriate visual areas. However, it is unclear whether both components are selective electrophysiological markers of attentional orienting toward emotional material or are also influenced by physical features of the visual stimuli. To address this question, electrical brain activity was recorded from seventeen male participants while viewing original and bright versions of neutral and erotic pictures. Bright neutral scenes were rated as more pleasant compared to their original counterpart, whereas erotic scenes were judged more positively when presented in their original version. Classical and mass univariate ERP analysis showed larger N1 amplitude for original relative to bright erotic pictures, with no differences for original and bright neutral scenes. Conversely, the EPN was only modulated by picture content and not by brightness, substantiating the idea that this component is a unique electrophysiological marker of attention allocation toward emotional material. Complementary topographic analysis revealed the early selective expression of a centro-parietal positivity following the presentation of original erotic scenes only, reflecting the recruitment of neural networks associated with sustained attention and facilitated memory encoding for motivationally relevant material. Overall, these results indicate that neural networks subtending the extraction of emotional information are differentially recruited depending on low-level perceptual features, which ultimately influence affective evaluations. Copyright © 2016 Elsevier Inc. All rights reserved.

The brightness of colour.

Directory of Open Access Journals (Sweden)

David Corney

Full Text Available The perception of brightness depends on spatial context: the same stimulus can appear light or dark depending on what surrounds it. A less well-known but equally important contextual phenomenon is that the colour of a stimulus can also alter its brightness. Specifically, stimuli that are more saturated (i.e. purer in colour appear brighter than stimuli that are less saturated at the same luminance. Similarly, stimuli that are red or blue appear brighter than equiluminant yellow and green stimuli. This non-linear relationship between stimulus intensity and brightness, called the Helmholtz-Kohlrausch (HK effect, was first described in the nineteenth century but has never been explained. Here, we take advantage of the relative simplicity of this 'illusion' to explain it and contextual effects more generally, by using a simple Bayesian ideal observer model of the human visual ecology. We also use fMRI brain scans to identify the neural correlates of brightness without changing the spatial context of the stimulus, which has complicated the interpretation of related fMRI studies.Rather than modelling human vision directly, we use a Bayesian ideal observer to model human visual ecology. We show that the HK effect is a result of encoding the non-linear statistical relationship between retinal images and natural scenes that would have been experienced by the human visual system in the past. We further show that the complexity of this relationship is due to the response functions of the cone photoreceptors, which themselves are thought to represent an efficient solution to encoding the statistics of images. Finally, we show that the locus of the response to the relationship between images and scenes lies in the primary visual cortex (V1, if not earlier in the visual system, since the brightness of colours (as opposed to their luminance accords with activity in V1 as measured with fMRI.The data suggest that perceptions of brightness represent a robust

Light emitting diodes for today's energy conscious world

Energy Technology Data Exchange (ETDEWEB)

Papanier, J

2000-10-01

The role played by light emitting diodes in back lighting, decorative illumination, emergency lighting, and automated signage are described as indicators of the many benefits and advantages of LED technology. The basic principles underlying the functioning of LEDs are explained, including the reasons behind their high efficiency in applications requiring colour. The difference between wattage and lumens is clarified; wattage refers to power consumption, whereas lumens measure brightness or light output, the measure most significant in the case of LEDs.

SKY BRIGHTNESS AND TRANSPARENCY IN THE i-BAND AT DOME A, ANTARCTICA

International Nuclear Information System (INIS)

Zou Hu; Zhou Xu; Jiang Zhaoji; Hu Jingyao; Ma Jun; Ashley, M. C. B.; Luong-Van, D. M.; Storey, J. W. V.; Cui Xiangqun; Feng Longlong; Gong Xuefei; Kulesa, C. A.; Lawrence, J. S.; Liu Genrong; Moore, A. M.; Pennypacker, C. R.; Travouillon, T.; Qin Weijia; Sun Bo; Shang Zhaohui

2010-01-01

The i-band observing conditions at Dome A on the Antarctic plateau have been investigated using data acquired during 2008 with the Chinese Small Telescope Array. The sky brightness, variations in atmospheric transparency, cloud cover, and the presence of aurorae are obtained from these images. The median sky brightness of moonless clear nights is 20.5 mag arcsec -2 in the SDSS i band at the south celestial pole (which includes a contribution of about 0.06 mag from diffuse Galactic light). The median over all Moon phases in the Antarctic winter is about 19.8 mag arcsec -2 . There were no thick clouds in 2008. We model contributions of the Sun and the Moon to the sky background to obtain the relationship between the sky brightness and transparency. Aurorae are identified by comparing the observed sky brightness to the sky brightness expected from this model. About 2% of the images are affected by relatively strong aurorae.

Space charge and wake field analysis for a high brightness electron source

International Nuclear Information System (INIS)

Parsa, Z.

1991-01-01

We present a brief overview of the formalism used, and some simulation results for transverse and longitudinal motion of a bunch of particles moving through a cavity (e.g., the Brookhaven National Laboratory high brightness photocathode gun), including effects of the accelerating field, space charge forces (e.g., arising from the interaction of the cavity surface and the self field of the bunch). 3 refs., 12 figs

High voltage high brightness electron accelerator with MITL voltage adder coupled to foilless diode

International Nuclear Information System (INIS)

Mazarakis, M.G.; Poulkey, J.W.; Rovang, D.

1995-01-01

The design and analysis of a high brightness electron beam experiment under construction at Sandia National Laboratory is presented. The beam energy is 12 MeV, the current 35-40 kA, the rms radius 0.5 mm, and the pulse duration FWHM 40 ns. The accelerator is SABRE a pulsed inductive voltage adder, and the electron source is a magnetically immersed foilless diode. This experiment has as its goal to stretch the technology to the edge and produce the highest possible electron current in a submillimeter radius beam

Low surface brightness galaxies in the cluster A1367

International Nuclear Information System (INIS)

Davies, J.I.; Phillipps, S.; Disney, M.J.

1989-01-01

We have obtained deep CCD frames of apparently blank regions of sky in the hope of detecting very low surface brightness (LSB) objects in the cluster A1367. We discuss our data reduction, and image detection and selection techniques. If the galaxies detected are actually cluster members then they are dwarfs and the conclusions of a previous paper on the Fornax cluster are essentially confirmed. One area of variance is that the lowest surface brightness galaxies do not appear to be preferentially concentrated towards the cluster centre. This can be explained by there being a much larger density of dwarf galaxies over this bright galaxy-rich region of the universe. We find over our small area approximately four times as many LSB galaxies as would be expected from our Fornax data. We speculate on the possible origin and likely intensity of intergalactic light within clusters. (author)

Status of the Advanced Light Source

International Nuclear Information System (INIS)

Marx, J.N.

1990-06-01

The Advanced Light Source (ALS), now under construction at the Lawrence Berkeley Laboratory, will be a national user facility for the production of high-brightness and partially coherent soft x-ray and ultraviolet synchrotron radiation. The ALS is based on a low-emittance electron storage ring optimized for operation at 1.5 GeV with insertion devices in 10 long straight sections and 24 premier bend-magnet ports. High-brightness photon beams, from less than 10 eV to more than 2 keV, will be produced by undulators, thereby providing many research opportunities in materials and surface science, biology, atomic physics and chemistry. Wigglers and bend magnets will provide high-flux, broad-band radiation at energies to 10 keV. 6 refs., 6 figs., 2 tabs

Photoluminescence, energy transfer and tunable color of Ce(3+), Tb(3+) and Eu(2+) activated oxynitride phosphors with high brightness.

Science.gov (United States)

Lü, Wei; Huo, Jiansheng; Feng, Yang; Zhao, Shuang; You, Hongpeng

2016-06-21

New tuneable light-emitting Ca3Al8Si4O17N4:Ce(3+)/Tb(3+)/Eu(2+) oxynitride phosphors with high brightness have been prepared. When doped with trivalent cerium or divalent europium they present blue luminescence under UV excitation. The energy transfer from Ce(3+) to Tb(3+) and Ce(3+) to Eu(2+) ions is deduced from the spectral overlap between Ce(3+) emission and Tb(3+)/Eu(2+) excitation spectra. The energy-transfer efficiencies and corresponding mechanisms are discussed in detail, and the mechanisms of energy transfer from the Ce(3+) to Tb(3+) and Ce(3+) to Eu(2+) ions are demonstrated to be a dipole-quadrupole and dipole-dipole mechanism, respectively, by the Inokuti-Hirayama model. The International Commission on Illumination value of color tuneable emission as well as luminescence quantum yield (23.8-80.6%) can be tuned by controlling the content of Ce(3+), Tb(3+) and Eu(2+). All results suggest that they are suitable for UV light-emitting diode excitation.

Working group II report: Production and dynamics of high brightness beams

International Nuclear Information System (INIS)

Sheffield, R.L.

1996-01-01

This paper summarizes the main discussions of the Working Group on the Production and Dynamics of High Brightness Beams. The following topics are covered in this paper. Proposed new electron sources and needed research on existing sources is covered. The discussions on issues relating to the description of phase space on non-thermalized electron beam distributions and the theoretical modeling on non-thermalized electron beam distributions is presented. Finally, the present status of the theoretical modeling of beam transport in bends is given

Flux and brightness calculations for various synchrotron radiation sources

International Nuclear Information System (INIS)

Weber, J.M.; Hulbert, S.L.

1991-11-01

Synchrotron radiation (SR) storage rings are powerful scientific and technological tools. The first generation of storage rings in the US., e.g., SURF (Washington, D.C.), Tantalus (Wisconsin), SSRL (Stanford), and CHESS (Cornell), revolutionized VUV, soft X-ray, and hard X-ray science. The second (present) generation of storage rings, e.g. the NSLS VUV and XRAY rings and Aladdin (Wisconsin), have sustained the revolution by providing higher stored currents and up to a factor of ten smaller electron beam sizes than the first generation sources. This has made possible a large number of experiments that could not performed using first generation sources. In addition, the NSLS XRAY ring design optimizes the performance of wigglers (high field periodic magnetic insertion devices). The third generation storage rings, e.g. ALS (Berkeley) and APS (Argonne), are being designed to optimize the performance of undulators (low field periodic magnetic insertion devices). These extremely high brightness sources will further revolutionize x-ray science by providing diffraction-limited x-ray beams. The output of undulators and wigglers is distinct from that of bending magnets in magnitude, spectral shape, and in spatial and angular size. Using published equations, we have developed computer programs to calculate the flux, central intensity, and brightness output bending magnets and selected wigglers and undulators of the NSLS VUV and XRAY rings, the Advanced Light Source (ALS), and the Advanced Photon Source (APS). Following is a summary of the equations used, the graphs and data produced, and the computer codes written. These codes, written in the C programming language, can be used to calculate the flux, central intensity, and brightness curves for bending magnets and insertion devices on any storage ring

Characterizing high-energy light curves of Fermi/Lat GRBs

Energy Technology Data Exchange (ETDEWEB)

Gillette, Jarred [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2015-08-21

A systematic analysis of the light curves of Gamma-Ray Burst (GRBs) with redshift and detected at high-energy (> 100 MeV) by Fermi/LAT has never been done before our work, because there were only a handful of detections. Now we have 20 of those, which we can use to characterize the GRBs in their rest frame. We compared a characteristic decay times Tc of GRBs with redshifts using the new “Pass 8” data, and used a Crystal Ball function to parametrize GRB characteristics. An unexpected anti-correlation between Tc and the peak flux was observed. This means that brighter peaked GRBs have shorter durations. There is also no correlation between the Tc and the decay index, which makes the anti-correlation with brightness more clear. This results appears to be consistent with the External Shock model, which is one of the competing hypothesis on the origin of the high-energy emission. We did not observe any bimodality, which is seen in GRBs at lower energies.

Effects of day-time exposure to different light intensities on light-induced melatonin suppression at night.

Science.gov (United States)

Kozaki, Tomoaki; Kubokawa, Ayaka; Taketomi, Ryunosuke; Hatae, Keisuke

2015-07-04

Bright nocturnal light has been known to suppress melatonin secretion. However, bright light exposure during the day-time might reduce light-induced melatonin suppression (LIMS) at night. The effective proportion of day-time light to night-time light is unclear; however, only a few studies on accurately controlling both day- and night-time conditions have been conducted. This study aims to evaluate the effect of different day-time light intensities on LIMS. Twelve male subjects between the ages of 19 and 23 years (mean ± S.D., 20.8 ± 1.1) gave informed consent to participate in this study. They were exposed to various light conditions (day-time light conditions). They were then exposed to bright light (300 lx) again between 01:00 and 02:30 (night-time light exposure). They provided saliva samples before (00:55) and after night-time light exposure (02:30). A one-tailed paired t test yielded significant decrements of melatonin concentration after night-time light exposure under day-time dim, 100- and 300-lx light conditions. No significant differences exist in melatonin concentration between pre- and post-night-time light exposure under day-time 900- and 2700-lx light conditions. Present findings suggest the amount of light exposure needed to prevent LIMS caused by ordinary nocturnal light in individuals who have a general life rhythm (sleep/wake schedule). These findings may be useful in implementing artificial light environments for humans in, for example, hospitals and underground shopping malls.

Extremely high-brightness kW-class fiber coupled diode lasers with wavelength stabilization

Science.gov (United States)

Huang, Robin K.; Chann, Bien; Glenn, John D.

2011-06-01

TeraDiode has produced ultra-high brightness fiber-coupled direct diode lasers. A fiber-coupled direct diode laser with a power level of 1,040 W from a 200 μm core diameter, 0.18 numerical aperture (NA) output fiber at a single center wavelength was demonstrated. This was achieved with a novel beam combining and shaping technique using COTS diode lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 18 mm-mrad and is the lowest BPP kW-class direct diode laser yet reported. The laser has been used to demonstrate laser cutting and welding of steel sheet metal up to 6.65 mm thick. Higher brightness fiber-coupled diode lasers, including a module with 418 W of power coupled to a 100 μm, 0.15 NA fiber, have also been demonstrated.

Fabrication of bright and thin Zn₂SiO₄ luminescent film for electron beam excitation-assisted optical microscope.

Science.gov (United States)

Furukawa, Taichi; Kanamori, Satoshi; Fukuta, Masahiro; Nawa, Yasunori; Kominami, Hiroko; Nakanishi, Yoichiro; Sugita, Atsushi; Inami, Wataru; Kawata, Yoshimasa

2015-07-13

We fabricated a bright and thin Zn₂SiO₄ luminescent film to serve as a nanometric light source for high-spatial-resolution optical microscopy based on electron beam excitation. The Zn₂SiO₄ luminescent thin film was fabricated by annealing a ZnO film on a Si₃N₄ substrate at 1000 °C in N₂. The annealed film emitted bright cathodoluminescence compared with the as-deposited film. The film is promising for nano-imaging with electron beam excitation-assisted optical microscopy. We evaluated the spatial resolution of a microscope developed using this Zn₂SiO₄ luminescent thin film. This is the first report of the investigation and application of ZnO/Si₃N₄ annealed at a high temperature (1000 °C). The fabricated Zn₂SiO₄ film is expected to enable high-frame-rate dynamic observation with ultra-high resolution using our electron beam excitation-assisted optical microscopy.

Electromagnetically induced transparency control in terahertz metasurfaces based on bright-bright mode coupling

Science.gov (United States)

Yahiaoui, R.; Burrow, J. A.; Mekonen, S. M.; Sarangan, A.; Mathews, J.; Agha, I.; Searles, T. A.

2018-04-01

We demonstrate a classical analog of electromagnetically induced transparency (EIT) in a highly flexible planar terahertz metamaterial (MM) comprised of three-gap split-ring resonators. The keys to achieve EIT in this system are the frequency detuning and hybridization processes between two bright modes coexisting in the same unit cell as opposed to bright-dark modes. We present experimental verification of two bright modes coupling for a terahertz EIT-MM in the context of numerical results and theoretical analysis based on a coupled Lorentz oscillator model. In addition, a hybrid variation of the EIT-MM is proposed and implemented numerically to dynamically tune the EIT window by incorporating photosensitive silicon pads in the split gap region of the resonators. As a result, this hybrid MM enables the active optical control of a transition from the on state (EIT mode) to the off state (dipole mode).

Efficiency optimization of green phosphorescent organic light-emitting device

Energy Technology Data Exchange (ETDEWEB)

Park, Jung Soo; Jeon, Woo Sik; Yu, Jae Hyung [Department of Information Display, Kyung Hee University, Dongdaemoon-gu, Seoul 130-701 (Korea, Republic of); Pode, Ramchandra, E-mail: rbpode@khu.ac.k [Department of Physics, Kyung Hee University, Dongdaemoon-gu, Seoul 130-701 (Korea, Republic of); Kwon, Jang Hyuk, E-mail: jhkwon@khu.ac.k [Department of Information Display, Kyung Hee University, Dongdaemoon-gu, Seoul 130-701 (Korea, Republic of)

2011-03-01

Using a narrow band gap host of bis[2-(2-hydroxyphenyl)-pyridine]beryllium (Bepp{sub 2}) and green phosphorescent Ir(ppy){sub 3} [fac-tris(2-phenylpyridine) iridium III] guest concentration as low as 2%, high efficiency phosphorescent organic light-emitting diode (PHOLED) is realized. Current and power efficiencies of 62.5 cd/A (max.), 51.0 lm/W (max.), and external quantum efficiency (max.) of 19.8% are reported in this green PHOLED. A low current efficiency roll-off value of 10% over the brightness of 10,000 cd/m{sup 2} is noticed in this Bepp{sub 2} single host device. Such a high efficiency is obtained by the optimization of the doping concentration with the knowledge of the hole trapping and the emission zone situations in this host-guest system. It is suggested that the reported device performance is suitable for applications in high brightness displays and lighting.

The Acute Effects of Intermittent Light Exposure in the Evening on Alertness and Subsequent Sleep Architecture.

Science.gov (United States)

Yang, Minqi; Ma, Ning; Zhu, Yingying; Su, Ying-Chu; Chen, Qingwei; Hsiao, Fan-Chi; Ji, Yanran; Yang, Chien-Ming; Zhou, Guofu

2018-03-15

Exposure to bright light is typically intermittent in our daily life. However, the acute effects of intermittent light on alertness and sleep have seldom been explored. To investigate this issue, we employed within-subject design and compared the effects of three light conditions: intermittent bright light (30-min pulse of blue-enriched bright light (~1000 lux, ~6000 K) alternating with 30-min dim normal light (~5 lux, ~3600 K) three times); continuous bright light; and continuous dim light on subjective and objective alertness and subsequent sleep structure. Each light exposure was conducted during the three hours before bedtime. Fifteen healthy volunteers (20 ± 3.4 years; seven males) were scheduled to stay in the sleep laboratory for four separated nights (one for adaptation and the others for the light exposures) with a period of at least one week between nights. The results showed that when compared with dim light, both intermittent light and continuous bright light significantly increased subjective alertness and decreased sleep efficiency (SE) and total sleep time (TST). Intermittent light significantly increased objective alertness than dim light did during the second half of the light-exposure period. Our results suggested that intermittent light was as effective as continuous bright light in their acute effects in enhancing subjective and objective alertness and in negatively impacting subsequent sleep.

The Acute Effects of Intermittent Light Exposure in the Evening on Alertness and Subsequent Sleep Architecture

Directory of Open Access Journals (Sweden)

Minqi Yang

2018-03-01

Full Text Available Exposure to bright light is typically intermittent in our daily life. However, the acute effects of intermittent light on alertness and sleep have seldom been explored. To investigate this issue, we employed within-subject design and compared the effects of three light conditions: intermittent bright light (30-min pulse of blue-enriched bright light (~1000 lux, ~6000 K alternating with 30-min dim normal light (~5 lux, ~3600 K three times; continuous bright light; and continuous dim light on subjective and objective alertness and subsequent sleep structure. Each light exposure was conducted during the three hours before bedtime. Fifteen healthy volunteers (20 ± 3.4 years; seven males were scheduled to stay in the sleep laboratory for four separated nights (one for adaptation and the others for the light exposures with a period of at least one week between nights. The results showed that when compared with dim light, both intermittent light and continuous bright light significantly increased subjective alertness and decreased sleep efficiency (SE and total sleep time (TST. Intermittent light significantly increased objective alertness than dim light did during the second half of the light-exposure period. Our results suggested that intermittent light was as effective as continuous bright light in their acute effects in enhancing subjective and objective alertness and in negatively impacting subsequent sleep.

Far infrared spectroscopy of high-Tc superconductors at the National Synchrotron Light Source

International Nuclear Information System (INIS)

Perkowitz, S.; Williams, G.P.

1989-01-01

This paper reports the first far infrared transmission spectra for micron-thick films of high-T c rare-earth superconductors such as DyBaCuO, with implications for the superconducting gap. Spectra were obtained at Brookhaven's National Synchrotron Light Source, a new high-intensity, broad-band millimeter to infrared source. The National Synchrotron Light Source at Brookhaven National Laboratory, known for powerful X-ray and UV output, is also a high-intensity (10 to 1000 times above a black body), high-brightness (intensity per solid angle), broad-band, picosecond, millimeter to infrared source. These features make it valuable for far-infrared condensed matter experiments, especially those in highly absorbing or extremely small systems. A first application has been to measure very small infrared transmissions through thick bulk-like high-T c superconducting films. Preliminary measurements through films of the conventional superconductor Nb 3 Ge established techniques. These were followed by the first measurements (to the author's knowledge) through micron-thick films of high-T c rare-earth superconductors such as DyBaCuO over 10-300 cm -1 , which includes the superconducting gap according to BCS or moderately strong-coupled theory. The authors discuss the transmission evidence bearing on the existence of a gap and other important features of high-T c superconductors, and describe the synchrotron and instrumentation features which make possible these unusual measurements

Generation of a high-brightness pulsed positron beam for the Munich scanning positron microscope

Energy Technology Data Exchange (ETDEWEB)

Piochacz, Christian

2009-11-20

Within the present work the prerequisites for the operation of the Munich scanning positron microscope (SPM) at the high intense neutron induced positron source Munich (NEPOMUC) were established. This was accomplished in two steps: Firstly, a re-moderation device was installed at the positron beam facility NEPOMUC, which enhances the brightness of the positron beam for all connected experiments. The second step was the design, set up and initial operation of the SPM interface for the high efficient conversion of the continuous beam into a bunched beam. The in-pile positron source NEPOMUC creates a positron beam with a diameter of typically 7 mm, a kinetic energy of 1 keV and an energy spread of 50 eV. The NEPOMUC re-moderator generates from this beam a low energy positron beam (20 - 200 eV) with a diameter of less than 2 mm and an energy spread well below 2.5 eV. This was achieved with an excellent total efficiency of 6.55{+-}0.25 %. The re-moderator was not only the rst step to implement the SPM at NEPOMUc, it enables also the operation of the pulsed low energy positron beam system (PLEPS). Within the present work, at this spectrometer rst positron lifetime measurements were performed, which revealed the defect types of an ion irradiated uranium molybdenum alloy. Moreover, the instruments which were already connected to the positron beam facility bene ts considerably of the high brightness enhancement. In the new SPM interface an additional re-moderation stage enhances the brightness of the beam even more and will enable positron lifetime measurements at the SPM with a lateral resolution below 1 {mu}m. The efficiency of the re-moderation process in this second stage was 24.5{+-}4.5 %. In order to convert high efficiently the continuous positron beam into a pulsed beam with a repetition rate of 50 MHz and a pulse duration of less than 50 ps, a sub-harmonic pre-bucher was combined with two sine wave bunchers. Furthermore, the additional re-moderation stage of the

Generation of a high-brightness pulsed positron beam for the Munich scanning positron microscope

International Nuclear Information System (INIS)

Piochacz, Christian

2009-01-01

Within the present work the prerequisites for the operation of the Munich scanning positron microscope (SPM) at the high intense neutron induced positron source Munich (NEPOMUC) were established. This was accomplished in two steps: Firstly, a re-moderation device was installed at the positron beam facility NEPOMUC, which enhances the brightness of the positron beam for all connected experiments. The second step was the design, set up and initial operation of the SPM interface for the high efficient conversion of the continuous beam into a bunched beam. The in-pile positron source NEPOMUC creates a positron beam with a diameter of typically 7 mm, a kinetic energy of 1 keV and an energy spread of 50 eV. The NEPOMUC re-moderator generates from this beam a low energy positron beam (20 - 200 eV) with a diameter of less than 2 mm and an energy spread well below 2.5 eV. This was achieved with an excellent total efficiency of 6.55±0.25 %. The re-moderator was not only the rst step to implement the SPM at NEPOMUc, it enables also the operation of the pulsed low energy positron beam system (PLEPS). Within the present work, at this spectrometer rst positron lifetime measurements were performed, which revealed the defect types of an ion irradiated uranium molybdenum alloy. Moreover, the instruments which were already connected to the positron beam facility bene ts considerably of the high brightness enhancement. In the new SPM interface an additional re-moderation stage enhances the brightness of the beam even more and will enable positron lifetime measurements at the SPM with a lateral resolution below 1 μm. The efficiency of the re-moderation process in this second stage was 24.5±4.5 %. In order to convert high efficiently the continuous positron beam into a pulsed beam with a repetition rate of 50 MHz and a pulse duration of less than 50 ps, a sub-harmonic pre-bucher was combined with two sine wave bunchers. Furthermore, the additional re-moderation stage of the SPM

Prediction of outcome of bright light treatment in patients with seasonal affective disorder: Discarding the early response, confirming a higher atypical balance, and uncovering a higher body mass index at baseline as predictors of endpoint outcome.

Science.gov (United States)

Dimitrova, Tzvetelina D; Reeves, Gloria M; Snitker, Soren; Lapidus, Manana; Sleemi, Aamar R; Balis, Theodora G; Manalai, Partam; Tariq, Muhammad M; Cabassa, Johanna A; Karim, Naila N; Johnson, Mary A; Langenberg, Patricia; Rohan, Kelly J; Miller, Michael; Stiller, John W; Postolache, Teodor T

2017-11-01

We tested the hypothesis that the early improvement in mood after the first hour of bright light treatment compared to control dim-red light would predict the outcome at six weeks of bright light treatment for depressed mood in patients with Seasonal Affective Disorder (SAD). We also analyzed the value of Body Mass Index (BMI) and atypical symptoms of depression at baseline in predicting treatment outcome. Seventy-eight adult participants were enrolled. The first treatment was controlled crossover, with randomized order, and included one hour of active bright light treatment and one hour of control dim-red light, with one-hour washout. Depression was measured on the Structured Interview Guide for the Hamilton Rating Scale for Depression-SAD version (SIGH-SAD). The predictive association of depression scores changes after the first session. BMI and atypical score balance with treatment outcomes at endpoint were assessed using multivariable linear and logistic regressions. No significant prediction by changes in depression scores after the first session was found. However, higher atypical balance scores and BMI positively predicted treatment outcome. Absence of a control intervention for the six-weeks of treatment (only the first session in the laboratory was controlled). Exclusion of patients with comorbid substance abuse, suicidality and bipolar I disorder, and patients on antidepressant medications, reducing the generalizability of the study. Prediction of outcome by early response to light treatment was not replicated, and the previously reported prediction of baseline atypical balance was confirmed. BMI, a parameter routinely calculated in primary care, was identified as a novel predictor, and calls for replication and then exploration of possible mediating mechanisms. Published by Elsevier B.V.

Can the season of birth risk factor for schizophrenia be prevented by bright light treatment for the second trimester mother around the winter solstice?

Science.gov (United States)

Schwartz, Paul J

2014-12-01

The season of birth risk factor for schizophrenia exerts a pervasive effect on the global population, particularly at northerly latitudes. The winter infection hypothesis and the low vitamin D hypothesis are both compelling but lack conclusive clinical data. The present work develops a maternal-fetal chronobiological hypothesis for this season of birth risk factor and its prevention by maternal bright light treatment. Around the winter solstice, due to decreased sunlight, the chronobiological apparatus of the at-risk second trimester mother is characterized by a reduced amplitude circadian pacemaker, and a reduced maximum of her nocturnal plasma melatonin concentrations (MTmax) and an increased minimum of her nocturnal core body temperatures (Tmin)--both of which exert adverse effects on the fetal hippocampus and dorsal striatum. The consequences for the fetus include reduced volume and increased excitability of the hippocampus, ventral striatal dysfunction, increased presynaptic nigrostriatal dopamine transmission, and increased propensity for pathological nigrostriatal neuronal phasic firing. Thus, the maternal-fetal chronobiological hypothesis fully accounts for the fetal precursors of the major pathognomonic abnormalities in adults with schizophrenia. Bright light treatment for the second trimester mother around the winter solstice, by increasing maternal circadian amplitude, could possibly prevent the fetal hippocampal and striatal abnormalities and eliminate the season of birth risk factor for schizophrenia. Copyright © 2014 Elsevier Ltd. All rights reserved.

Lighting up your product! : The influence of retail lighting on product perception

NARCIS (Netherlands)

Creusen, M.E.H.; Pont, S.C.; Schoormans, J.P.L.

2017-01-01

This research is one of the first attempts to shed light on the influence of different lighting characteristics on consumer product perception. Study 1 looked at the influence of light level (i.e., brightness) and color temperature on consumer perception of a sneaker and a toaster. Study 2 assessed

Beam position monitors for the high brightness lattice

International Nuclear Information System (INIS)

Ring, T.

1985-06-01

Engineering developments associated with the high brightness lattice and the projected change in machine operating parameters will inherently affect the diagnostics systems and devices installed at present in the storage ring. This is particularly true of the beam position monitoring (BPI) system. The new sixteen unit cell lattice with its higher betatron tune values and the limited space available in the redesigned machine straights for fitting standard BPI vessels forces a fundamental re-evaluation of the beam position monitor system. The design aims for the new system are based on accepting the space limitations imposed while still providing the monitor points required to give good radial and vertical closed orbit plots. The locations of BPI's in the redesigned machine straights is illustrated. A description of the new BPI assemblies and their calibration is given. The BPI's use capacitance button type pick-ups; their response is described. (U.K.)

Can light make us bright? Effects of light on cognition and sleep

NARCIS (Netherlands)

Chellappa, Sarah Laxhmi; Gordijn, Marijke C. M.; Cajochen, Christian; VanDongen, HPA; Kerkhof, GA

2011-01-01

Light elicits robust nonvisual effects on numerous physiological and behavioral variables, such as the human sleep-wake cycle and cognitive performance. Light effects crucially rely on properties such as dose, duration, timing, and wavelength. Recently, the use of methods such as fMRI to assess

Source brightness fluctuation correction of solar absorption fourier transform mid infrared spectra

Directory of Open Access Journals (Sweden)

T. Ridder

2011-06-01

Full Text Available The precision and accuracy of trace gas observations using solar absorption Fourier Transform infrared spectrometry depend on the stability of the light source. Fluctuations in the source brightness, however, cannot always be avoided. Current correction schemes, which calculate a corrected interferogram as the ratio of the raw DC interferogram and a smoothed DC interferogram, are applicable only to near infrared measurements. Spectra in the mid infrared spectral region below 2000 cm⁻¹ are generally considered uncorrectable, if they are measured with a MCT detector. Such measurements introduce an unknown offset to MCT interferograms, which prevents the established source brightness fluctuation correction. This problem can be overcome by a determination of the offset using the modulation efficiency of the instrument. With known modulation efficiency the offset can be calculated, and the source brightness correction can be performed on the basis of offset-corrected interferograms. We present a source brightness fluctuation correction method which performs the smoothing of the raw DC interferogram in the interferogram domain by an application of a running mean instead of high-pass filtering the corresponding spectrum after Fourier transformation of the raw DC interferogram. This smoothing can be performed with the onboard software of commercial instruments. The improvement of MCT spectra and subsequent ozone profile and total column retrievals is demonstrated. Application to InSb interferograms in the near infrared spectral region proves the equivalence with the established correction scheme.

Highly efficient phosphorescent blue and white organic light-emitting devices with simplified architectures

Energy Technology Data Exchange (ETDEWEB)

Chang, Chih-Hao, E-mail: chc@saturn.yzu.edu.tw [Department of Photonics Engineering, Yuan Ze University, Chung-Li, Taiwan 32003 (China); Ding, Yong-Shung; Hsieh, Po-Wei; Chang, Chien-Ping; Lin, Wei-Chieh [Department of Photonics Engineering, Yuan Ze University, Chung-Li, Taiwan 32003 (China); Chang, Hsin-Hua, E-mail: hhua3@mail.vnu.edu.tw [Department of Electro-Optical Engineering, Vanung University, Chung-Li, Taiwan 32061 (China)

2011-09-01

Blue phosphorescent organic light-emitting devices (PhOLEDs) with quantum efficiency close to the theoretical maximum were achieved by utilizing a double-layer architecture. Two wide-triplet-gap materials, 1,3-bis(9-carbazolyl)benzene and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, were employed in the emitting and electron-transport layers respectively. The opposite carrier-transport characteristics of these two materials were leveraged to define the exciton formation zone and thus increase the probability of recombination. The efficiency at practical luminance (100 cd/m{sup 2}) was as high as 20.8%, 47.7 cd/A and 31.2 lm/W, respectively. Furthermore, based on the design concept of this simplified architecture, efficient warmish-white PhOLEDs were developed. Such two-component white organic light-emitting devices exhibited rather stable colors over a wide brightness range and yielded electroluminescence efficiencies of 15.3%, 33.3 cd/A, and 22.7 lm/W in the forward directions.

Highly efficient phosphorescent blue and white organic light-emitting devices with simplified architectures

International Nuclear Information System (INIS)

Chang, Chih-Hao; Ding, Yong-Shung; Hsieh, Po-Wei; Chang, Chien-Ping; Lin, Wei-Chieh; Chang, Hsin-Hua

2011-01-01

Blue phosphorescent organic light-emitting devices (PhOLEDs) with quantum efficiency close to the theoretical maximum were achieved by utilizing a double-layer architecture. Two wide-triplet-gap materials, 1,3-bis(9-carbazolyl)benzene and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, were employed in the emitting and electron-transport layers respectively. The opposite carrier-transport characteristics of these two materials were leveraged to define the exciton formation zone and thus increase the probability of recombination. The efficiency at practical luminance (100 cd/m 2 ) was as high as 20.8%, 47.7 cd/A and 31.2 lm/W, respectively. Furthermore, based on the design concept of this simplified architecture, efficient warmish-white PhOLEDs were developed. Such two-component white organic light-emitting devices exhibited rather stable colors over a wide brightness range and yielded electroluminescence efficiencies of 15.3%, 33.3 cd/A, and 22.7 lm/W in the forward directions.

The surface brightness of spiral galaxies: Pt. 4

International Nuclear Information System (INIS)

Phillipps, S.; Disney, M.; Ohio State Univ., Columbus

1988-01-01

Using measurements from IRAS correlations are found between optical surface brightness and both infrared-to-optical flux ratio and infrared colour temperature, in the sense that galaxies with high surface brightness have higher FIR emission and higher temperatures. (author)

Development of low emittance high brightness electron beams and rf accelerating structures

International Nuclear Information System (INIS)

Pellegrini, C.

1991-01-01

The main goals of this project were the construction of an S-band RF photoinjector for the production of a high brightness electron beam, and the development of a new type of RF accelerator structure; the Plane wave transformer. By the end of October 1991 the photoinjector had been built, its RF characteristics had been measured at low power, and an initial test of the gun at high RF power had been done. The Plane Wave Transformer had also been built and tested at lower power. In both cases the results obtained are mostly in agreement with the expected and calculated behavior

Contrasting trends in light pollution across Europe based on satellite observed night time lights.

Science.gov (United States)

Bennie, Jonathan; Davies, Thomas W; Duffy, James P; Inger, Richard; Gaston, Kevin J

2014-01-21

Since the 1970s nighttime satellite images of the Earth from space have provided a striking illustration of the extent of artificial light. Meanwhile, growing awareness of adverse impacts of artificial light at night on scientific astronomy, human health, ecological processes and aesthetic enjoyment of the night sky has led to recognition of light pollution as a significant global environmental issue. Links between economic activity, population growth and artificial light are well documented in rapidly developing regions. Applying a novel method to analysis of satellite images of European nighttime lights over 15 years, we show that while the continental trend is towards increasing brightness, some economically developed regions show more complex patterns with large areas decreasing in observed brightness over this period. This highlights that opportunities exist to constrain and even reduce the environmental impact of artificial light pollution while delivering cost and energy-saving benefits.

High-efficiency, 154  W CW, diode-pumped Raman fiber laser with brightness enhancement.

Science.gov (United States)

Glick, Yaakov; Fromzel, Viktor; Zhang, Jun; Ter-Gabrielyan, Nikolay; Dubinskii, Mark

2017-01-20

We demonstrate a high-power, high-efficiency Raman fiber laser pumped directly by laser diode modules at 978 nm. 154 W of CW power were obtained at a wavelength of 1023 nm with an optical to optical efficiency of 65%. A commercial graded-index (GRIN) core fiber acts as the Raman fiber in a power oscillator configuration, which includes spectral selection to prevent generation of the second Stokes. In addition, brightness enhancement of the pump beam by a factor of 8.4 is attained due to the Raman gain distribution profile in the GRIN fiber. To the best of our knowledge this is the highest power and highest efficiency Raman fiber laser demonstrated in any configuration allowing brightness enhancement (i.e., in either cladding-pumped configuration or with GRIN fibers, excluding step-index core pumped), regardless of pumping scheme (i.e., either diode pumped or fiber laser pumped).

Colours in black and white: the depiction of lightness and brightness in achromatic engravings before the invention of photography.

Science.gov (United States)

Zavagno, Daniele; Massironi, Manfredo

2006-01-01

What is it like to see the world in black and white? In the pioneer days of cinema, when movies displayed grey worlds, was it true that no 'colours' were actually seen? Did every object seen in those projections appear grey in the same way? The answer is obviously no--people in those glorious days were seeing a world full of light, shadows, and objects in which colours were expressed in terms of lightness. But the marvels of grey worlds have not always been so richly displayed. Before the invention of photography, the depiction of scenes in black-and-white had to face some technical and perceptual challenges. We have studied the technical and perceptual constraints that XV-XVIII century engravers had to face in order to translate actual colours into shades of grey. An indeterminacy principle is considered, according to which artists had to prefer the representation of some object or scene features over others (for example brightness over lightness). The reasons for this lay between the kind of grey scale technically available and the kind of information used in the construction of 3-D scenes. With the invention of photography, photomechanical reproductions, and new printing solutions, artists had at their disposal a continuous grey scale that greatly reduces the constraints of the indeterminacy principle.

High-brightness tapered laser diodes with photonic crystal structures

Science.gov (United States)

Li, Yi; Du, Weichuan; Kun, Zhou; Gao, Songxin; Ma, Yi; Tang, Chun

2018-02-01

Beam quality of tapered laser diodes is limited by higher order lateral mode. On purpose of optimizing the brightness of tapered laser diodes, we developed a novel design of tapered diodes. This devices based on InGaAs/AlGaAs asymmetry epitaxial structure, containing higher order lateral mode filtering schemes especially photonic crystal structures, which fabricated cost effectively by using standard photolithography and dry etch processes. Meanwhile, the effects of photonic crystal structures on mode control are also investigated theoretically by FDBPM (Finite-Difference Beam Propagation Method) calculation. We achieved a CW optical output power of 6.9W at 940nm for a single emitter with 4 mm cavity length. A nearly diffraction limited beam of M2 ≍1.9 @ 0.5W has been demonstrated, and a highest brightness of β =75MW/(cm2 ·sr) was reached.

ENHANCEMENT OF A SUNSPOT LIGHT WALL WITH EXTERNAL DISTURBANCES

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuhong; Zhang, Jun [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Erdélyi, Robert, E-mail: shuhongyang@nao.cas.cn [Solar Physics and Space Plasma Research Centre, School of Mathematics and Statistics, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

2016-12-20

Based on the Interface Region Imaging Spectrograph observations, we study the response of a solar sunspot light wall to external disturbances. A flare occurrence near the light wall caused material to erupt from the lower solar atmosphere into the corona. Some material falls back to the solar surface and hits the light bridge (i.e., the base of the light wall), then sudden brightenings appear at the wall base followed by the rise of wall top, leading to an increase of the wall height. Once the brightness of the wall base fades, the height of the light wall begins to decrease. Five hours later, another nearby flare takes place, and a bright channel is formed that extends from the flare toward the light bridge. Although no obvious material flow along the bright channel is found, some ejected material is conjectured to reach the light bridge. Subsequently, the wall base brightens and the wall height begins to increase again. Once more, when the brightness of the wall base decays, the wall top fluctuates to lower heights. We suggest, based on the observed cases, that the interaction of falling material and ejected flare material with the light wall results in the brightenings of wall base and causes the height of the light wall to increase. Our results reveal that the light wall can be not only powered by the linkage of p -mode from below the photosphere, but may also be enhanced by external disturbances, such as falling material.

Label-free detection of cellular drug responses by high-throughput bright-field imaging and machine learning.

Science.gov (United States)

Kobayashi, Hirofumi; Lei, Cheng; Wu, Yi; Mao, Ailin; Jiang, Yiyue; Guo, Baoshan; Ozeki, Yasuyuki; Goda, Keisuke

2017-09-29

In the last decade, high-content screening based on multivariate single-cell imaging has been proven effective in drug discovery to evaluate drug-induced phenotypic variations. Unfortunately, this method inherently requires fluorescent labeling which has several drawbacks. Here we present a label-free method for evaluating cellular drug responses only by high-throughput bright-field imaging with the aid of machine learning algorithms. Specifically, we performed high-throughput bright-field imaging of numerous drug-treated and -untreated cells (N = ~240,000) by optofluidic time-stretch microscopy with high throughput up to 10,000 cells/s and applied machine learning to the cell images to identify their morphological variations which are too subtle for human eyes to detect. Consequently, we achieved a high accuracy of 92% in distinguishing drug-treated and -untreated cells without the need for labeling. Furthermore, we also demonstrated that dose-dependent, drug-induced morphological change from different experiments can be inferred from the classification accuracy of a single classification model. Our work lays the groundwork for label-free drug screening in pharmaceutical science and industry.

Selection effects in the bivariate brightness distribution for spiral galaxies

International Nuclear Information System (INIS)

Phillipps, S.; Disney, M.

1986-01-01

The joint distribution of total luminosity and characteristic surface brightness (the bivariate brightness distribution) is investigated for a complete sample of spiral galaxies in the Virgo cluster. The influence of selection and physical limits of various kinds on the apparent distribution are detailed. While the distribution of surface brightness for bright galaxies may be genuinely fairly narrow, faint galaxies exist right across the (quite small) range of accessible surface brightnesses so no statement can be made about the true extent of the distribution. The lack of high surface brightness bright galaxies in the Virgo sample relative to an overall RC2 sample (mostly field galaxies) supports the contention that the star-formation rate is reduced in the inner region of the cluster for environmental reasons. (author)

Low surface brightness spiral galaxies

International Nuclear Information System (INIS)

Romanishin, W.

1980-01-01

This dissertation presents an observational overview of a sample of low surface brightness (LSB) spiral galaxies. The sample galaxies were chosen to have low surface brightness disks and indications of spiral structure visible on the Palomar Sky Survey. They are of sufficient angular size (diameter > 2.5 arcmin), to allow detailed surface photometry using Mayall 4-m prime focus plates. The major findings of this dissertation are: (1) The average disk central surface brightness of the LSB galaxies is 22.88 magnitude/arcsec 2 in the B passband. (2) From broadband color measurements of the old stellar population, we infer a low average stellar metallicity, on the order of 1/5 solar. (3) The spectra and optical colors of the HII regions in the LSB galaxies indicate a lack of hot ionizing stars compared to HII regions in other late-type galaxies. (4) The average surface mass density, measured within the radius containing half the total mass, is less than half that of a sample of normal late-type spirals. (5) The average LSB galaxy neutral hydrogen mass to blue luminosity ratio is about 0.6, significantly higher than in a sample of normal late-type galaxies. (6) We find no conclusive evidence of an abnormal mass-to-light ratio in the LSB galaxies. (7) Some of the LSB galaxies exhibit well-developed density wave patterns. (8) A very crude calculation shows the lower metallicity of the LSB galaxies compared with normal late-type spirals might be explained simply by the deficiency of massive stars in the LSB galaxies

High-energy Neutrino Flares from X-Ray Bright and Dark Tidal Disruption Events

Energy Technology Data Exchange (ETDEWEB)

Senno, Nicholas; Murase, Kohta; Mészáros, Peter [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)

2017-03-20

X-ray and γ-ray observations by the Swift satellite revealed that a fraction of tidal disruption events (TDEs) have relativistic jets. Jetted TDEs have been considered to be potential sources of very-high-energy cosmic-rays and neutrinos. In this work, using semi-analytical methods, we calculate neutrino spectra of X-ray bright TDEs with powerful jets and dark TDEs with possible choked jets, respectively. We estimate their neutrino fluxes and find that non-detection would give us an upper limit on the baryon loading of the jet luminosity contained in cosmic-rays ξ {sub cr} ≲ 20–50 for Sw J1644+57. We show that X-ray bright TDEs make a sub-dominant (≲5%–10%) contribution to IceCube’s diffuse neutrino flux, and study possible contributions of X-ray dark TDEs given that particles are accelerated in choked jets or disk winds. We discuss future prospects for multi-messenger searches of the brightest TDEs.

Atomic physics with high-brightness synchrotron x-ray sources

International Nuclear Information System (INIS)

Jones, K.W.; Johnson, B.M.; Meron, M.

1985-11-01

A description of atomic physics experiments that we intend to carry out at the National Synchrotron Light Source is given. Emphasis is given to work that investigates the properties of multiply charged ions. The use of a synchrotron storage ring for highly charged heavy ions is proposed as a way to produce high current beams which will make possible experiments to study the photoexcitation and ionization of multiply charged ions for the first time. Experiments along the same lines which are feasible at the proposed Advanced Light Source are considered briefly. 7 refs., 2 figs

Simultaneous brightness contrast of foraging Papilio butterflies

Science.gov (United States)

Kinoshita, Michiyo; Takahashi, Yuki; Arikawa, Kentaro

2012-01-01

This study focuses on the sense of brightness in the foraging Japanese yellow swallowtail butterfly, Papilio xuthus. We presented two red discs of different intensity on a grey background to butterflies, and trained them to select one of the discs. They were successfully trained to select either a high intensity or a low intensity disc. The trained butterflies were tested on their ability to perceive brightness in two different protocols: (i) two orange discs of different intensity presented on the same intensity grey background and (ii) two orange discs of the same intensity separately presented on a grey background that was either higher or lower in intensity than the training background. The butterflies trained to high intensity red selected the orange disc of high intensity in protocol 1, and the disc on the background of low intensity grey in protocol 2. We obtained similar results in another set of experiments with purple discs instead of orange discs. The choices of the butterflies trained to low intensity red were opposite to those just described. Taken together, we conclude that Papilio has the ability to learn brightness and darkness of targets independent of colour, and that they have the so-called simultaneous brightness contrast. PMID:22179808

Dynamics of annular bright field imaging in scanning transmission electron microscopy

International Nuclear Information System (INIS)

Findlay, S.D.; Shibata, N.; Sawada, H.; Okunishi, E.; Kondo, Y.; Ikuhara, Y.

2010-01-01

We explore the dynamics of image formation in the so-called annular bright field mode in scanning transmission electron microscopy, whereby an annular detector is used with detector collection range lying within the cone of illumination, i.e. the bright field region. We show that this imaging mode allows us to reliably image both light and heavy columns over a range of thickness and defocus values, and we explain the contrast mechanisms involved. The role of probe and detector aperture sizes is considered, as is the sensitivity of the method to intercolumn spacing and local disorder.

Restoration and Enhancement of Underwater Images Based on Bright Channel Prior

Directory of Open Access Journals (Sweden)

Yakun Gao

2016-01-01

Full Text Available This paper proposed a new method of underwater images restoration and enhancement which was inspired by the dark channel prior in image dehazing field. Firstly, we proposed the bright channel prior of underwater environment. By estimating and rectifying the bright channel image, estimating the atmospheric light, and estimating and refining the transmittance image, eventually underwater images were restored. Secondly, in order to rectify the color distortion, the restoration images were equalized by using the deduced histogram equalization. The experiment results showed that the proposed method could enhance the quality of underwater images effectively.

First results of the spatial and temporal variation of the night sky brightness in the surroundings of Valencia

Science.gov (United States)

Marco, E.; Morales Rubio, A.; Zamorano, J.; Sánchez de Miguel, A.

2017-03-01

In recent years a study of the quality of the night sky in the surroundings of the metropolitan area of Valencia has been done. To achieve this, we used a Sky Quality Meter (SQM-LE) together with a GPS in order to cover a large number of routes from very bright locations near the city of Valencia to very dark areas located more than 100 kilometres away. The objectives of the study were to determine the variation of light pollution with respect to the distance to Valencia, locate areas with a high quality night sky in order to claim for their protection and verify the contribution of smaller towns in the brightness of the sky. Since light pollution also affects biodiversity, we have especially studied its influence on the night sky close to natural parks. Night routes have been done in the interior and vicinity of the Parc de la Calderona, the Albufera and especially the Parc del T ´uria. Our study concludes that these parks are completely degraded and need an urgent protection plan against light pollution. Finally, we present the first results of our fixed detectors SQM-LU scattered throughout the Valencian territory.

Effect of bright light and melatonin on cognitive and noncognitive function in elderly residents of group care facilities: a randomized controlled trial.

Science.gov (United States)

Riemersma-van der Lek, Rixt F; Swaab, Dick F; Twisk, Jos; Hol, Elly M; Hoogendijk, Witte J G; Van Someren, Eus J W

2008-06-11

Cognitive decline, mood, behavioral and sleep disturbances, and limitations of activities of daily living commonly burden elderly patients with dementia and their caregivers. Circadian rhythm disturbances have been associated with these symptoms. To determine whether the progression of cognitive and noncognitive symptoms may be ameliorated by individual or combined long-term application of the 2 major synchronizers of the circadian timing system: bright light and melatonin. A long-term, double-blind, placebo-controlled, 2 x 2 factorial randomized trial performed from 1999 to 2004 with 189 residents of 12 group care facilities in the Netherlands; mean (SD) age, 85.8 (5.5) years; 90% were female and 87% had dementia. Random assignment by facility to long-term daily treatment with whole-day bright (+/- 1000 lux) or dim (+/- 300 lux) light and by participant to evening melatonin (2.5 mg) or placebo for a mean (SD) of 15 (12) months (maximum period of 3.5 years). Standardized scales for cognitive and noncognitive symptoms, limitations of activities of daily living, and adverse effects assessed every 6 months. Light attenuated cognitive deterioration by a mean of 0.9 points (95% confidence interval [CI], 0.04-1.71) on the Mini-Mental State Examination or a relative 5%. Light also ameliorated depressive symptoms by 1.5 points (95% CI, 0.24-2.70) on the Cornell Scale for Depression in Dementia or a relative 19%, and attenuated the increase in functional limitations over time by 1.8 points per year (95% CI, 0.61-2.92) on the nurse-informant activities of daily living scale or a relative 53% difference. Melatonin shortened sleep onset latency by 8.2 minutes (95% CI, 1.08-15.38) or 19% and increased sleep duration by 27 minutes (95% CI, 9-46) or 6%. However, melatonin adversely affected scores on the Philadelphia Geriatric Centre Affect Rating Scale, both for positive affect (-0.5 points; 95% CI, -0.10 to -1.00) and negative affect (0.8 points; 95% CI, 0.20-1.44). Melatonin

Generating a high brightness multi-kilowatt laser by dense spectral combination of VBG stabilized single emitter laser diodes

Science.gov (United States)

Fritsche, H.; Koch, Ralf; Krusche, B.; Ferrario, F.; Grohe, Andreas; Pflueger, S.; Gries, W.

2014-05-01

Generating high power laser radiation with diode lasers is commonly realized by geometrical stacking of diode bars, which results in high output power but poor beam parameter product (BPP). The accessible brightness in this approach is limited by the fill factor, both in slow and fast axis. By using a geometry that accesses the BPP of the individual diodes, generating a multi kilowatt diode laser with a BPP comparable to fiber lasers is possible. We will demonstrate such a modular approach for generating multi kilowatt lasers by combining single emitter diode lasers. Single emitter diodes have advantages over bars, mainly a simplified cooling, better reliability and a higher brightness per emitter. Additionally, because single emitters can be arranged in many different geometries, they allow building laser modules where the brightness of the single emitters is preserved. In order to maintain the high brightness of the single emitter we developed a modular laser design which uses single emitters in a staircase arrangement, then coupling two of those bases with polarization combination which is our basic module. Those modules generate up to 160 W with a BPP better than 7.5 mm*mrad. For further power scaling wavelength stabilization is crucial. The wavelength is stabilized with only one Volume Bragg Grating (VBG) in front of a base providing the very same feedback to all of the laser diodes. This results in a bandwidth of BPP better than 7.5 mm*mrad, which can easily coupled into a 100 μm fiber and 0.15 NA.

Supercontinuum light sources for food analysis

DEFF Research Database (Denmark)

Møller, Uffe Visbech; Petersen, Christian Rosenberg; Kubat, Irnis

2014-01-01

. One track of Light & Food will target the mid-infrared spectral region. To date, the limitations of mid-infraredlight sources, such as thermal emitters, low-power laser diodes, quantum cascade lasers and synchrotron radiation, have precluded mid-IR applications where the spatial coherence, broad...... bandwidth,high brightness and portability of a supercontinuum laser are all required. DTU Fotonik has now demonstrated the first optical fiber based broadband supercontinuum light souce, which covers 1.4-13.3μm and thereby most of the molecular fingerprint region....

Acute Effects of Morning Light on Plasma Glucose and Triglycerides in Healthy Men and Men with Type 2 Diabetes

Science.gov (United States)

Versteeg, Ruth I.; Stenvers, Dirk J.; Visintainer, Dana; Linnenbank, Andre; Tanck, Michael W.; Zwanenburg, Gooitzen; Smilde, Age K.; Fliers, Eric; Kalsbeek, Andries; Serlie, Mireille J.; la Fleur, Susanne E.; Bisschop, Peter H.

2017-01-01

Ambient light intensity is signaled directly to hypothalamic areas that regulate energy metabolism. Observational studies have shown associations between ambient light intensity and plasma glucose and lipid levels, but human data on the acute metabolic effects of light are scarce. Since light is the main signal indicating the onset of the diurnal phase of physical activity and food intake in humans, we hypothesized that bright light would affect glucose and lipid metabolism. Therefore, we determined the acute effects of bright light on plasma glucose and lipid concentrations in 2 randomized crossover trials: (1) in 8 healthy lean men and (2) in 8 obese men with type 2 diabetes. From 0730 h, subjects were exposed to either bright light (4000 lux) or dim light (10 lux) for 5 h. After 1 h of light exposure, subjects consumed a 600-kcal mixed meal. Primary endpoints were fasting and postprandial plasma glucose levels. In healthy men, bright light did not affect fasting or postprandial plasma glucose levels. However, bright light increased fasting and postprandial plasma triglycerides. In men with type 2 diabetes, bright light increased fasting and postprandial glucose levels. In men with type 2 diabetes, bright light did not affect fasting triglyceride levels but increased postprandial triglyceride levels. We show that ambient light intensity acutely affects human plasma glucose and triglyceride levels. Our findings warrant further research into the consequences of the metabolic effects of light for the diagnosis and prevention of hyperglycemia and dyslipidemia. PMID:28470119

Session 21.2 - Measurement of Light at Night

Science.gov (United States)

Wainscoat, Richard J.

2016-10-01

The introduction of the mercury vapor lamp for general lighting in the 1930s probably marked the beginning of significant light pollution. Lighting levels have increased slowly, year-to-year, with sky brightness levels increasing only slowly on timescales of a year; no measurement protocols or instruments existed to quantify this increase. However, on timescales of 10-20 years, or on generational timescales, the increases in night sky levels, particularly in urban areas, have been dramatic. Younger people speak with their parents or grandparents who remark how beautiful the sky used to be, and how many stars they could see when they when they were younger. Older people can themselves remember how many stars were visible in the sky when they were younger. Whole generations of children now grow up without ever seeing the Milky Way. Society has not had tools to easily measure sky brightness, and monitoring from space has only recently become available. A subtle increase of 10% sky brightness per year, for example, is not noticeable to the human eye on the time scale of a year, and has been tolerated by society. But such an increase compounds to an increase of a factor 2.6 in 10 years, 6.7 in 20 years, and a factor 45 in 40 years, corresponding to a dramatic increase in sky brightness, an almost complete loss in ability to see faint objects in the night sky, and rendering the sky unusable for most forms of astronomy. The most striking examples are the urban observatories found in many major cities that can no longer be used. Session 2 was primarily focused on measurement of light at night, with an emphasis on measurement of light pollution. It comprised of 6 papers that are summarized below. Over the last decade, our ability to measure light pollution has grown tremendously, and the instrumentation needed to produce reliable quantitative measurements has become much more affordable, and now includes consumer grade digital cameras and even smart phones. During this same

On correct evaluation techniques of brightness enhancement effect measurement data

Science.gov (United States)

Kukačka, Leoš; Dupuis, Pascal; Motomura, Hideki; Rozkovec, Jiří; Kolář, Milan; Zissis, Georges; Jinno, Masafumi

2017-11-01

This paper aims to establish confidence intervals of the quantification of brightness enhancement effects resulting from the use of pulsing bright light. It is found that the methods used so far may yield significant bias in the published results, overestimating or underestimating the enhancement effect. The authors propose to use a linear algebra method called the total least squares. Upon an example dataset, it is shown that this method does not yield biased results. The statistical significance of the results is also computed. It is concluded over an observation set that the currently used linear algebra methods present many patterns of noise sensitivity. Changing algorithm details leads to inconsistent results. It is thus recommended to use the method with the lowest noise sensitivity. Moreover, it is shown that this method also permits one to obtain an estimate of the confidence interval. This paper neither aims to publish results about a particular experiment nor to draw any particular conclusion about existence or nonexistence of the brightness enhancement effect.

Velocity bunching of high-brightness electron beams

Directory of Open Access Journals (Sweden)

S. G. Anderson

2005-01-01

Full Text Available Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly

Fabrication and characterization of high-brightness light emitting diodes based on n-ZnO nanorods grown by a low-temperature chemical method on p-4H-SiC and p-GaN

International Nuclear Information System (INIS)

Alvi, N H; Riaz, M; Tzamalis, G; Nur, O; Willander, M

2010-01-01

Light emitting diodes (LEDs) based on n-ZnO nanorods (NRs)/p-4H-SiC and n-ZnO (NRs)/p-GaN were fabricated and characterized. For the two LEDs the ZnO NRs were grown using a low temperature (<100 °C) aqueous chemical growth (ACG) technique. Both LEDs showed very bright nearly white light electroluminescence (EL) emission. The observed luminescence was a result of the combination of three emission lines composed of violet-blue, green and orange-red peaks observed from the two LEDs. Room temperature photoluminescence (PL) was also measured and consistency with EL was observed. It was found that the green and violet-blue peaks are red-shifted while the orange peak is blue-shifted in the EL measurement. It was also found that due to the effect of the GaN substrate the violet-blue peak in the EL measurement is more red-shifted in n-ZnO (NRs)/p-GaN LEDs as compared to n-ZnO (NRs)/p-4H-SiC LEDs

Light-emitting diodes - Their potential in biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Yeh, Naichia Gary; Wu, Chia-Hao [College of Applied Sciences, MingDao University, 369 Wen-Hua Road, Peetou, Changhua 52345 (China); Cheng, Ta Chih [Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, 1 Hseuh-Fu Rd., Nei-Pu Hsiang, Pingtung 91201 (China)

2010-10-15

The rapid development of high brightness light-emitting diodes (LEDs) makes feasible the use of LEDs, among other light sources (such as laser, intense pulse light and other incoherent light systems), for medical treatment and light therapy. This paper provides a general review on red, green, blue, ultraviolet LED applications in photo rejuvenation and medical treatments of a variety of physical abnormalities, as well as the relief of stress, circadian rhythm disorders, and seasonal affective disorder. The review, concentrated in the papers published after 1990, intends to show that LEDs are well qualified to succeed its more energy demanding counterparts in the named areas and beyond. (author)

High brightness--multiple beamlets source for patterned X-ray production

Science.gov (United States)

Leung, Ka-Ngo [Hercules, CA; Ji, Qing [Albany, CA; Barletta, William A [Oakland, CA; Jiang, Ximan [El Cerrito, CA; Ji, Lili [Albany, CA

2009-10-27

Techniques for controllably directing beamlets to a target substrate are disclosed. The beamlets may be either positive ions or electrons. It has been shown that beamlets may be produced with a diameter of 1 .mu.m, with inter-aperture spacings of 12 .mu.m. An array of such beamlets, may be used for maskless lithography. By step-wise movement of the beamlets relative to the target substrate, individual devices may be directly e-beam written. Ion beams may be directly written as well. Due to the high brightness of the beamlets from extraction from a multicusp source, exposure times for lithographic exposure are thought to be minimized. Alternatively, the beamlets may be electrons striking a high Z material for X-ray production, thereafter collimated to provide patterned X-ray exposures such as those used in CAT scans. Such a device may be used for remote detection of explosives.

Strategy Guideline: High Performance Residential Lighting

Energy Technology Data Exchange (ETDEWEB)

Holton, J.

2012-02-01

The Strategy Guideline: High Performance Residential Lighting has been developed to provide a tool for the understanding and application of high performance lighting in the home. The high performance lighting strategies featured in this guide are drawn from recent advances in commercial lighting for application to typical spaces found in residential buildings. This guide offers strategies to greatly reduce lighting energy use through the application of high quality fluorescent and light emitting diode (LED) technologies. It is important to note that these strategies not only save energy in the home but also serve to satisfy the homeowner's expectations for high quality lighting.

A MULTIWAVELENGTH STUDY OF THE HIGH SURFACE BRIGHTNESS HOT SPOT IN PKS 1421-490

International Nuclear Information System (INIS)

Godfrey, L. E. H.; Bicknell, G. V.; Lovell, J. E. J.; Jauncey, D. L.; Gelbord, J.; Schwartz, D. A.; Birkinshaw, M.; Worrall, D. M.; Marshall, H. L.; Georganopoulos, M.; Perlman, E. S.; Murphy, D. W.

2009-01-01

Long Baseline Array imaging of the z = 0.663 broadline radio galaxy PKS 1421-490 reveals a 400 pc diameter high surface brightness hot spot at a projected distance of ∼40 kpc from the active galactic nucleus. The isotropic X-ray luminosity of the hot spot, L 2-10keV = 3 x 10 44 ergs s -1 , is comparable to the isotropic X-ray luminosity of the entire X-ray jet of PKS 0637-752, and the peak radio surface brightness is hundreds of times greater than that of the brightest hot spot in Cygnus A. We model the radio to X-ray spectral energy distribution using a one-zone synchrotron self-Compton model with a near equipartition magnetic field strength of 3 mG. There is a strong brightness asymmetry between the approaching and receding hotspots and the hot spot spectrum remains flat (α ∼ 0.5) well beyond the predicted cooling break for a 3 mG magnetic field, indicating that the hotspot emission may be Doppler beamed. A high plasma velocity beyond the terminal jet shock could be the result of a dynamically important magnetic field in the jet. There is a change in the slope of the hotspot radio spectrum at GHz frequencies, which we model by incorporating a cutoff in the electron energy distribution at γ min ∼ 650, with higher values implied if the hotspot emission is Doppler beamed. We show that a sharp decrease in the electron number density below a Lorentz factor of 650 would arise from the dissipation of bulk kinetic energy in an electron/proton jet with a Lorentz factor Γ jet ∼> 5.

Accompanying of parameters of color, brightness and hardness on polymeric films coated with pigmented inks cured by different radiation doses of ultraviolet light

International Nuclear Information System (INIS)

Bardi, M.A.G.; Machado, L.D.B.

2011-01-01

Complete text of publication follows. In the search for alternatives to traditional paint systems containing solvents, the curing process of polymer coatings by ultraviolet (UV) light has been widely studied and discussed, specially because of their high content of solids and null emission of VOCs. Radiation curing is defined as the conversion of a reactive liquid into a solid through polymerization and crosslinking reactions between the species, promoted by the interaction of the chemical system with the incident ionizing radiation. The appearance of the coated object (e.g., color, gloss) is a complex function of the light incident on the object, the optical scattering characteristic of the material, and human perception. Pigments are very fine powders being nearly insoluble in binders and solvents, but provide color and the ability to hide the underlying surface. In this context, this paper aims to investigate variations on color, brightness and hardness of UV-cured pigmented coatings by different doses. When it comes to irradiation exposition, the incorporation of pigments can preferentially cause its reflection or absorption of the incident radiation. Reflection usually occurs at the pigment surface within the resin so that the radiation has to pass through the top layers twice. Some degradation can, therefore, occur at the surface, and this is why materials frequently lose gloss on exposure.

The bright optical afterglow of the long GRB 001007

DEFF Research Database (Denmark)

Ceron, J.M.C.; Castro-Tirado, A.J.; Gorosabel, J.

2002-01-01

We present optical follow up observations of the long GRB 001007 between 6.14 hours and similar to468 days after the event. An unusually bright optical afterglow (OA) was seen to decline following a steep power law decay with index alpha = -2.03 +/- 0.11, possibly indicating a break in the light...... curve at t - t(0) hours after the gamma ray event provide tentative (1.2σ) evidence for a break in the optical light curve. The spectral index β of the OA yields -1.24 +/- 0.57. These values may be explained both...

High-brightness switchable multiwavelength remote laser in air

Energy Technology Data Exchange (ETDEWEB)

Yao Jinping; Cheng Ya; Xu Zhizhan [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Zeng Bin; Li Guihua; Chu Wei; Ni Jielei; Zhang Haisu [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of Chinese Academy of Sciences, Beijing 100080 (China); Xu Huailiang [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Chin, See Leang [Center for Optics, Universite Laval, Quebec City, Quebec G1V 0A6 (Canada)

2011-11-15

We demonstrate a harmonic-seeded switchable multiwavelength laser in air driven by intense midinfrared femtosecond laser pulses, in which population inversion occurs at an ultrafast time scale (i.e., less than {approx}200 fs) owing to direct formation of excited molecular nitrogen ions by strong-field ionization of inner-valence electrons. The bright multiwavelength laser in air opens the perspective for remote detection of multiple pollutants based on nonlinear optical spectroscopy.

Impact of the ADT on the beam quality with high brightness beams in collision (MD2155)

CERN Document Server

Buffat, Xavier; Kostoglou, Sofia; Salvachua Ferrando, Belen Maria; Papadopoulou, Parthena Stefania; Ponce, Laurette; Solfaroli Camillocci, Matteo; Suykerbuyk, Ronaldus; Valuch, Daniel; Walsh, David John; Barranco Garcia, Javier; Pieloni, Tatiana; CERN. Geneva. ATS Department

2018-01-01

The results of an experiment aiming at determining indirectly the noise level in the LHC, isolating the contribution of the transverse damper, through their impact on the emittance of colliding high brightness bunches at 6.5 TeV in the LHC are presented.

High-brightness electron beam evolution following laser-based cleaning of a photocathode

Directory of Open Access Journals (Sweden)

F. Zhou

2012-09-01

Full Text Available Laser-based techniques have been widely used for cleaning metal photocathodes to increase quantum efficiency (QE. However, the impact of laser cleaning on cathode uniformity and thereby on electron beam quality are less understood. We are evaluating whether this technique can be applied to revive photocathodes used for high-brightness electron sources in advanced x-ray free-electron laser (FEL facilities, such as the Linac Coherent Light Source (LCLS at the SLAC National Accelerator Laboratory. The laser-based cleaning was applied to two separate areas of the current LCLS photocathode on July 4 and July 26, 2011, respectively. The QE was increased by 8–10 times upon the laser cleaning. Since the cleaning, routine operation has exhibited a slow evolution of the QE improvement and comparatively rapid improvement of transverse emittance, with a factor of 3 QE enhancement over five months, and a significant emittance improvement over the initial 2–3 weeks following the cleaning. Currently, the QE of the LCLS photocathode is holding constant at about 1.2×10^{-4}, with a normalized injector emittance of about 0.3  μm for a 150-pC bunch charge. With the proper procedures, the laser-cleaning technique appears to be a viable tool to revive the LCLS photocathode. We present observations and analyses for the QE and emittance evolution in time following the laser-based cleaning of the LCLS photocathode, and comparison to the previous studies, the measured thermal emittance versus the QE and comparison to the theoretical model.

Sleep deprivation in bright and dim light : antidepressant effects on major depressive disorder

NARCIS (Netherlands)

Burg, W. van den; Bouhuys, A.L.; Hoofdakker, R.H. van den; Beersma, D.G.M.

Twenty-three patients with a major depressive disorder were deprived of a night’s sleep twice weekly, one week staying up in the dimly lit living room of the ward (< 60 lux), and one week in a brightly lit room (> 2000 lux). Immediate, but transient beneficial effects of sleep deprivation were

THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. I. BRIGHT UV STARS IN THE BULGE OF M31

International Nuclear Information System (INIS)

Rosenfield, Philip; Johnson, L. Clifton; Dalcanton, Julianne J.; Williams, Benjamin F.; Gilbert, Karoline M.; Girardi, Léo; Bressan, Alessandro; Lang, Dustin; Guhathakurta, Puragra; Dorman, Claire E.; Howley, Kirsten M.; Lauer, Tod R.; Olsen, Knut A. G.; Bell, Eric F.; Bianchi, Luciana; Caldwell, Nelson; Dolphin, Andrew; Kalirai, Jason; Larsen, Søren S.; Rix, Hans-Walter

2012-01-01

As part of the Panchromatic Hubble Andromeda Treasury multi-cycle program, we observed a 12' × 6.'5 area of the bulge of M31 with the WFC3/UVIS filters F275W and F336W. From these data we have assembled a sample of ∼4000 UV-bright, old stars, vastly larger than previously available. We use updated Padova stellar evolutionary tracks to classify these hot stars into three classes: Post-AGB stars (P-AGB), Post-Early AGB (PE-AGB) stars, and AGB-manqué stars. P-AGB stars are the end result of the asymptotic giant branch (AGB) phase and are expected in a wide range of stellar populations, whereas PE-AGB and AGB-manqué (together referred to as the hot post-horizontal branch; HP-HB) stars are the result of insufficient envelope masses to allow a full AGB phase, and are expected to be particularly prominent at high helium or α abundances when the mass loss on the red giant branch is high. Our data support previous claims that most UV-bright sources in the bulge are likely hot (extreme) horizontal branch (EHB) stars and their progeny. We construct the first radial profiles of these stellar populations and show that they are highly centrally concentrated, even more so than the integrated UV or optical light. However, we find that this UV-bright population does not dominate the total UV luminosity at any radius, as we are detecting only the progeny of the EHB stars that are the likely source of the UV excess. We calculate that only a few percent of main-sequence stars in the central bulge can have gone through the HP-HB phase and that this percentage decreases strongly with distance from the center. We also find that the surface density of hot UV-bright stars has the same radial variation as that of low-mass X-ray binaries. We discuss age, metallicity, and abundance variations as possible explanations for the observed radial variation in the UV-bright population.

Final Report on DTRA Basic Research Project #BRCALL08-Per3-C-2-0006 "High-Z Non-Equilibrium Physics and Bright X-ray Sources with New Laser Targets"

Energy Technology Data Exchange (ETDEWEB)

Colvin, Jeffrey D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-06-01

This project had two major goals. Final Goal: obtain spectrally resolved, absolutely calibrated x-ray emission data from uniquely uniform mm-scale near-critical-density high-Z plasmas not in local thermodynamic equilibrium (LTE) to benchmark modern detailed atomic physics models. Scientific significance: advance understanding of non-LTE atomic physics. Intermediate Goal: develop new nano-fabrication techniques to make suitable laser targets that form the required highly uniform non-LTE plasmas when illuminated by high-intensity laser light. Scientific significance: advance understanding of nano-science. The new knowledge will allow us to make x-ray sources that are bright at the photon energies of most interest for testing radiation hardening technologies, the spectral energy range where current x-ray sources are weak. All project goals were met.

Advanced chip designs and novel cooling techniques for brightness scaling of industrial, high power diode laser bars

Science.gov (United States)

Heinemann, S.; McDougall, S. D.; Ryu, G.; Zhao, L.; Liu, X.; Holy, C.; Jiang, C.-L.; Modak, P.; Xiong, Y.; Vethake, T.; Strohmaier, S. G.; Schmidt, B.; Zimer, H.

2018-02-01

The advance of high power semiconductor diode laser technology is driven by the rapidly growing industrial laser market, with such high power solid state laser systems requiring ever more reliable diode sources with higher brightness and efficiency at lower cost. In this paper we report simulation and experimental data demonstrating most recent progress in high brightness semiconductor laser bars for industrial applications. The advancements are in three principle areas: vertical laser chip epitaxy design, lateral laser chip current injection control, and chip cooling technology. With such improvements, we demonstrate disk laser pump laser bars with output power over 250W with 60% efficiency at the operating current. Ion implantation was investigated for improved current confinement. Initial lifetime tests show excellent reliability. For direct diode applications 96% polarization are additional requirements. Double sided cooling deploying hard solder and optimized laser design enable single emitter performance also for high fill factor bars and allow further power scaling to more than 350W with 65% peak efficiency with less than 8 degrees slow axis divergence and high polarization.

ROLE OF DIAMOND SECONDARY EMITTERS IN HIGH BRIGHTNESS ELECTRON SOURCES

International Nuclear Information System (INIS)

2005-01-01

In this paper we explore the possibility of using diamond secondary emitter in a high average current electron injector to amplify the current from the photocathode and to isolate the cathode and the injector from each other to increase the life time of the cathode and preserve the performance of the injector. Secondary electron yield of 225 and current density of 0.8 a/cm 2 have been measured in the transmission mode from type 2 a natural diamond. Although the diamond will be heated during normal operation in the injector, calculations indicate that by cryogenically cooling the diamond, the temperature gradient along the diamond can be maintained within the acceptable range. The electron energy and temporal distributions are expected to be narrow from this device resulting in high brightness beams. Plans are underway to measure the SEY in emission mode, fabricate photocathode-diamond capsule and test diamond and capsule in superconducting RF injector

Combination of light and melatonin time cues for phase advancing the human circadian clock.

Science.gov (United States)

Burke, Tina M; Markwald, Rachel R; Chinoy, Evan D; Snider, Jesse A; Bessman, Sara C; Jung, Christopher M; Wright, Kenneth P

2013-11-01

Photic and non-photic stimuli have been shown to shift the phase of the human circadian clock. We examined how photic and non-photic time cues may be combined by the human circadian system by assessing the phase advancing effects of one evening dose of exogenous melatonin, alone and in combination with one session of morning bright light exposure. Randomized placebo-controlled double-blind circadian protocol. The effects of four conditions, dim light (∼1.9 lux, ∼0.6 Watts/m(2))-placebo, dim light-melatonin (5 mg), bright light (∼3000 lux, ∼7 Watts/m(2))-placebo, and bright light-melatonin on circadian phase was assessed by the change in the salivary dim light melatonin onset (DLMO) prior to and following treatment under constant routine conditions. Melatonin or placebo was administered 5.75 h prior to habitual bedtime and 3 h of bright light exposure started 1 h prior to habitual wake time. Sleep and chronobiology laboratory environment free of time cues. Thirty-six healthy participants (18 females) aged 22 ± 4 y (mean ± SD). Morning bright light combined with early evening exogenous melatonin induced a greater phase advance of the DLMO than either treatment alone. Bright light alone and melatonin alone induced similar phase advances. Information from light and melatonin appear to be combined by the human circadian clock. The ability to combine circadian time cues has important implications for understanding fundamental physiological principles of the human circadian timing system. Knowledge of such principles is important for designing effective countermeasures for phase-shifting the human circadian clock to adapt to jet lag, shift work, and for designing effective treatments for circadian sleep-wakefulness disorders.

Study of the X-ray binary AM Herculis. II - Spectrophotometry at maximum light

International Nuclear Information System (INIS)

Voikhanskaia, N.F.

1980-01-01

The spectrum of the AM Her system at maximum light is analyzed, and a comparison is made between the spectra when the system is at different levels of brightness. At maximum light the equivalent line widths fluctuate rapidly on a time scale of about 1 min at all phases of the orbit period. As the brightness drops, the system becomes less strongly excited consequently, the high-excitation elements represented in the spectrum first fade and then vanish. At maximum light the bulk of the radiation comes from the hottest and densest parts of the luminous region. As the light wanes the contribution of their radiation to the total light of the system diminishes, and the radiation of the cooler, more tenuous parts of the emission region becomes perceptible. In addition, the pronounced change in the shape of the emission-line profiles during the orbital period at minimum light implies a considerable amount of irregularity in the region producing the lines, unlike the uniform emission region at maximum light

Effects of electromagnetic radiation (bright light, extremely low-frequency magnetic fields, infrared radiation) on the circadian rhythm of melatonin synthesis, rectal temperature, and heart rate.

Science.gov (United States)

Griefahn, Barbara; Künemund, Christa; Blaszkewicz, Meinolf; Lerchl, Alexander; Degen, Gisela H

2002-10-01

Electromagnetic spectra reduce melatonin production and delay the nadirs of rectal temperature and heart rate. Seven healthy men (16-22 yrs) completed 4 permuted sessions. The control session consisted of a 24-hours bedrest at infrared radiation (65 degrees C) was applied from 5 pm to 1 am. Salivary melatonin level was determined hourly, rectal temperature and heart rate were continuously recorded. Melatonin synthesis was completely suppressed by light but resumed thereafter. The nadirs of rectal temperature and heart rate were delayed. The magnetic field had no effect. Infrared radiation elevated rectal temperature and heart rate. Only bright light affected the circadian rhythms of melatonin synthesis, rectal temperature, and heart rate, however, differently thus causing a dissociation, which might enhance the adverse effects of shiftwork in the long run.

[Negotiating light therapy. Kellogg versus Finsen, and the controversy about the health effects of light rays around 1900].

Science.gov (United States)

Ingold, Niklaus

2015-07-01

Western medicine has produced different rationales for the application of light rays to cure diseases in the 201h century. Since the 1980s, physicians have used bright light for treating mental disorders. In the interwar period, however, physicians regarded ultraviolet rays rather than bright light as medically relevant. This view goes back to the 1890s, when the physician (and later Nobel Price laureate) Niels R. Finsen started treating skin tuberculosis with light rays. However, Finsen was not the only physician who utilized the new electric light to develop effective therapies. Famous American inventor of the breakfast cereal and eugenicists, John Harvey Kellogg used incandescent lamps to heat a sweatbox. Consequently, two different therapeutic schools emerged from these therapeutic experiments. This article shows how these two schools negotiated the use of light therapy and how a specific idea of medically interesting light rays emerged thereby.

There is nothing paranormal about near-death experiences: how neuroscience can explain seeing bright lights, meeting the dead, or being convinced you are one of them.

Science.gov (United States)

Mobbs, Dean; Watt, Caroline

2011-10-01

Approximately 3% of Americans declare to have had a near-death experience. These experiences classically involve the feeling that one's soul has left the body, approaches a bright light and goes to another reality, where love and bliss are all encompassing. Contrary to popular belief, research suggests that there is nothing paranormal about these experiences. Instead, near-death experiences are the manifestation of normal brain function gone awry, during a traumatic, and sometimes harmless, event. Copyright © 2011 Elsevier Ltd. All rights reserved.

Bright Single-Photon Sources Based on Anti-Reflection Coated Deterministic Quantum Dot Microlenses

Directory of Open Access Journals (Sweden)

Peter Schnauber

2015-12-01

Full Text Available We report on enhancing the photon-extraction efficiency (PEE of deterministic quantum dot (QD microlenses via anti-reflection (AR coating. The AR-coating deposited on top of the curved microlens surface is composed of a thin layer of Ta2O5, and is found to effectively reduce back-reflection of light at the semiconductor-vacuum interface. A statistical analysis of spectroscopic data reveals, that the AR-coating improves the light out-coupling of respective microlenses by a factor of 1.57 ± 0.71, in quantitative agreement with numerical calculations. Taking the enhancement factor into account, we predict improved out-coupling of light with a PEE of up to 50%. The quantum nature of emission from QDs integrated into AR-coated microlenses is demonstrated via photon auto-correlation measurements revealing strong suppression of two-photon emission events with g(2(0 = 0.05 ± 0.02. As such, these bright non-classical light sources are highly attractive with respect to applications in the field of quantum cryptography.

Workplace lighting for improving alertness and mood in daytime workers.

Science.gov (United States)

Pachito, Daniela V; Eckeli, Alan L; Desouky, Ahmed S; Corbett, Mark A; Partonen, Timo; Rajaratnam, Shantha Mw; Riera, Rachel

2018-03-02

Exposure to light plays a crucial role in biological processes, influencing mood and alertness. Daytime workers may be exposed to insufficient or inappropriate light during daytime, leading to mood disturbances and decreases in levels of alertness. To assess the effectiveness and safety of lighting interventions to improve alertness and mood in daytime workers. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, seven other databases; ClinicalTrials.gov and the World Health Organization trials portal up to January 2018. We included randomised controlled trials (RCTs), and non-randomised controlled before-after trials (CBAs) that employed a cross-over or parallel-group design, focusing on any type of lighting interventions applied for daytime workers. Two review authors independently screened references in two stages, extracted outcome data and assessed risk of bias. We used standardised mean differences (SMDs) and 95% confidence intervals (CI) to pool data from different questionnaires and scales assessing the same outcome across different studies. We combined clinically homogeneous studies in a meta-analysis. We used the GRADE system to rate quality of evidence. The search yielded 2844 references. After screening titles and abstracts, we considered 34 full text articles for inclusion. We scrutinised reports against the eligibility criteria, resulting in the inclusion of five studies (three RCTs and two CBAs) with 282 participants altogether. These studies evaluated four types of comparisons: cool-white light, technically known as high correlated colour temperature (CCT) light versus standard illumination; different proportions of indirect and direct light; individually applied blue-enriched light versus no treatment; and individually applied morning bright light versus afternoon bright light for subsyndromal seasonal affective disorder.We found no studies comparing one level of illuminance versus another.We found two CBA

High brightness potassium ion gun for the HIF neutralized transport experiment (NTX)

International Nuclear Information System (INIS)

Eylon, S.; Henestroza, E.; Roy, P.K.; Yu, S.S.

2003-01-01

The NTX experiment at the Heavy Ion Fusion Virtual National Laboratory is exploring the performance of neutralized final focus systems for high perveance heavy ion beams. To focus a high intensity beam to a small spot requires a high brightness beam. In the NTX experiment, a potassium ion beam of up to 400 keV and 80 mA is generated in a Pierce type diode. At the diode exit, an aperture with variable size provides the capability to vary the beam perveance and to significantly reduce the beam emittance. We shall report on the gun characterization including current density profile, phase space distributions and the control of electrons generated by the beam scraping at the aperture. Comparison with particle simulations using the EGUN code will be presented

Ultra High Brightness/Low Cost Fiber Coupled Packaging, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — High peak power, high efficiency, high reliability lightweight, low cost QCW laser diode pump modules with up to 1000W of QCW output become possible with nLight's...

A Next Generation Light Source Facility at LBNL

International Nuclear Information System (INIS)

Corlett, J.N.; Austin, B.; Baptiste, K.M.; Byrd, J.M.; Denes, P.; Donahue, R.; Doolittle, L.; Falcone, R.W.; Filippetto, D.; Fournier, S.; Li, D.; Padmore, H.A.; Papadopoulos, C.; Pappas, C.; Penn, G.; Placidi, M.; Prestemon, S.; Prosnitz, D.; Qiang, J.; Ratti, A.; Reinsch, M.; Sannibale, F.; Schlueter, R.; Schoenlein, R.W.; Staples, J.W.; Vecchione, T.; Venturini, M.; Wells, R.; Wilcox, R.; Wurtele, J.; Charman, A.; Kur, E.; Zholents, A.A.

2011-01-01

The Next Generation Light Source (NGLS) is a design concept, under development at LBNL, for a multibeamline soft x-ray FEL array powered by a ∼2 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. The CW superconducting linear accelerator is supplied by a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for EEHG, HGHG, SASE, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format, with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds.

Temporary blinding from bright light sources as a significant impact on occupational safety and health

International Nuclear Information System (INIS)

Reidenbach, Hans-Dieter

2008-01-01

Low power laser and high-brightness LEDs (HB-LEDs) have been applied in specially developed and computer assisted test setups in order to determine the duration and progression of colours in afterimages, the disturbance of visual acuity as well as the impairment of colour and contrast vision. Interrelationships between wavelength, exposure duration, optical power and energy have been investigated. Afterimage durations up to 300 seconds were found if the fovea of the human retina is irradiated from a laser beam at less than 30 μW, whereas lower values are valid in the Parafoveal region and in the periphery. The visual acuity was strongly reduced during about 30 % of the afterimage time. The time-dependent progression of the afterimage colours was determined for 4 different dominant wavelengths of HB-LEDs, i.e. 455 nm, 530 nm, 590 nm and 625 nm, in the power range between 0.05 m W and 0.5 m W for exposure durations between 0.5 s and 5 s. The flight of colours obtained with 5 test persons is given as 8-bit RGB-values and illustrated as a function of the applied optical energy in the CIE chromaticity diagram together with the respective total afterimage durations. The colour contrast capability was investigated for 3 volunteers with specially developed test charts in 7 colours, namely without and after glare from 4 coloured high-brightness LEDs. Each subject completed 56 time-consuming tests since adequate adaptation was necessary between the respective tests. Glare increases the identification times about 14 s and 16 s and even stronger impairment is observable especially at low colour contrast. Tests with 40 subjects and 4 different pseudoisochromatic colour plates have shown that colour vision was impaired for periods between 27 s and 186 s depending on the applied colour plate and respective LED colour. Such relatively long lasting visual disturbances could be of particular concern connected with performing safety critical operations such as working with machines

Release from the cone ribbon synapse under bright light conditions can be controlled by the opening of only a few Ca(2+) channels.

Science.gov (United States)

Bartoletti, Theodore M; Jackman, Skyler L; Babai, Norbert; Mercer, Aaron J; Kramer, Richard H; Thoreson, Wallace B

2011-12-01

Light hyperpolarizes cone photoreceptors, causing synaptic voltage-gated Ca(2+) channels to open infrequently. To understand neurotransmission under these conditions, we determined the number of L-type Ca(2+) channel openings necessary for vesicle fusion at the cone ribbon synapse. Ca(2+) currents (I(Ca)) were activated in voltage-clamped cones, and excitatory postsynaptic currents (EPSCs) were recorded from horizontal cells in the salamander retina slice preparation. Ca(2+) channel number and single-channel current amplitude were calculated by mean-variance analysis of I(Ca). Two different comparisons-one comparing average numbers of release events to average I(Ca) amplitude and the other involving deconvolution of both EPSCs and simultaneously recorded cone I(Ca)-suggested that fewer than three Ca(2+) channel openings accompanied fusion of each vesicle at the peak of release during the first few milliseconds of stimulation. Opening fewer Ca(2+) channels did not enhance fusion efficiency, suggesting that few unnecessary channel openings occurred during strong depolarization. We simulated release at the cone synapse, using empirically determined synaptic dimensions, vesicle pool size, Ca(2+) dependence of release, Ca(2+) channel number, and Ca(2+) channel properties. The model replicated observations when a barrier was added to slow Ca(2+) diffusion. Consistent with the presence of a diffusion barrier, dialyzing cones with diffusible Ca(2+) buffers did not affect release efficiency. The tight clustering of Ca(2+) channels, along with a high-Ca(2+) affinity release mechanism and diffusion barrier, promotes a linear coupling between Ca(2+) influx and vesicle fusion. This may improve detection of small light decrements when cones are hyperpolarized by bright light.

Giant Low Surface Brightness Galaxies

Science.gov (United States)

Mishra, Alka; Kantharia, Nimisha G.; Das, Mousumi

2018-04-01

In this paper, we present radio observations of the giant low surface brightness (LSB) galaxies made using the Giant Metrewave Radio Telescope (GMRT). LSB galaxies are generally large, dark matter dominated spirals that have low star formation efficiencies and large HI gas disks. Their properties suggest that they are less evolved compared to high surface brightness galaxies. We present GMRT emission maps of LSB galaxies with an optically-identified active nucleus. Using our radio data and archival near-infrared (2MASS) and near-ultraviolet (GALEX) data, we studied morphology and star formation efficiencies in these galaxies. All the galaxies show radio continuum emission mostly associated with the centre of the galaxy.

The distribution of star formation and metals in the low surface brightness galaxy UGC 628

Science.gov (United States)

Young, J. E.; Kuzio de Naray, Rachel; Wang, Sharon X.

2015-09-01

We introduce the MUSCEL Programme (MUltiwavelength observations of the Structure, Chemistry and Evolution of LSB galaxies), a project aimed at determining the star-formation histories of low surface brightness galaxies. MUSCEL utilizes ground-based optical spectra and space-based UV and IR photometry to fully constrain the star-formation histories of our targets with the aim of shedding light on the processes that led low surface brightness galaxies down a different evolutionary path from that followed by high surface brightness galaxies, such as our Milky Way. Here we present the spatially resolved optical spectra of UGC 628, observed with the VIRUS-P IFU at the 2.7-m Harlen J. Smith Telescope at the McDonald Observatory, and utilize emission-line diagnostics to determine the rate and distribution of star formation as well as the gas-phase metallicity and metallicity gradient. We find highly clustered star formation throughout UGC 628, excluding the core regions, and a log(O/H) metallicity around -4.2, with more metal-rich regions near the edges of the galactic disc. Based on the emission-line diagnostics alone, the current mode of star formation, slow and concentrated in the outer disc, appears to have dominated for quite some time, although there are clear signs of a much older stellar population formed in a more standard inside-out fashion.

BrightFocus Foundation

Science.gov (United States)

... About BrightFocus Foundation Featured Content BrightFocus: Investing in Science to Save Mind and Sight We're here to help. Explore ... recognition is very important. Monday, November 6, 2017 New Diagnosis? Managing a mind and sight disease is a journey. And you’ ...

The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering

Science.gov (United States)

Pilipenko, S. V.; Kovalev, Y. Y.; Andrianov, A. S.; Bach, U.; Buttaccio, S.; Cassaro, P.; Cimò, G.; Edwards, P. G.; Gawroński, M. P.; Gurvits, L. I.; Hovatta, T.; Jauncey, D. L.; Johnson, M. D.; Kovalev, Yu A.; Kutkin, A. M.; Lisakov, M. M.; Melnikov, A. E.; Orlati, A.; Rudnitskiy, A. G.; Sokolovsky, K. V.; Stanghellini, C.; de Vicente, P.; Voitsik, P. A.; Wolak, P.; Zhekanis, G. V.

2018-03-01

The high brightness temperatures, Tb ≳ 1013 K, detected in several active galactic nuclei by RadioAstron space VLBI observations challenge theoretical limits. Refractive scattering by the interstellar medium may affect such measurements. We quantify the scattering properties and the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstron correlated flux density measurements at 1.7, 4.8, and 22 GHz on projected baselines up to 240 000 km we find two characteristic angular scales in the quasar core, about 100 and 10 μas. Some indications of scattering substructure are found. Very high brightness temperatures, Tb ≥ 1013 K, are estimated at 4.8 and 22 GHz even taking into account the refractive scattering. Our findings suggest a clear dominance of the particle energy density over the magnetic field energy density in the core of this quasar.

Color and emotion: effects of hue, saturation, and brightness.

Science.gov (United States)

Wilms, Lisa; Oberfeld, Daniel

2017-06-13

Previous studies on emotional effects of color often failed to control all the three perceptual dimensions of color: hue, saturation, and brightness. Here, we presented a three-dimensional space of chromatic colors by independently varying hue (blue, green, red), saturation (low, medium, high), and brightness (dark, medium, bright) in a factorial design. The 27 chromatic colors, plus 3 brightness-matched achromatic colors, were presented via an LED display. Participants (N = 62) viewed each color for 30 s and then rated their current emotional state (valence and arousal). Skin conductance and heart rate were measured continuously. The emotion ratings showed that saturated and bright colors were associated with higher arousal. The hue also had a significant effect on arousal, which increased from blue and green to red. The ratings of valence were the highest for saturated and bright colors, and also depended on the hue. Several interaction effects of the three color dimensions were observed for both arousal and valence. For instance, the valence ratings were higher for blue than for the remaining hues, but only for highly saturated colors. Saturated and bright colors caused significantly stronger skin conductance responses. Achromatic colors resulted in a short-term deceleration in the heart rate, while chromatic colors caused an acceleration. The results confirm that color stimuli have effects on the emotional state of the observer. These effects are not only determined by the hue of a color, as is often assumed, but by all the three color dimensions as well as their interactions.

Simple, compact, high brightness source for x-ray lithography and x-ray radiography

International Nuclear Information System (INIS)

Hawryluk, A.M.

1986-01-01

A simple, compact, high brightness x-ray source has recently been built. This source utilizes a commercially available, cylindrical geometry electron beam evaporator, which has been modified to enhance the thermal cooling to the anode. Cooling is accomplished by using standard, low-conductivity laboratory water, with an inlet pressure of less than 50 psi, and a flow rate of approx.0.3 gal/min. The anode is an inverted cone geometry for efficient cooling. The x-ray source has a measured sub-millimeter spot size (FWHM). The anode has been operated at 1 KW e-beam power (10 KV, 100 ma). Higher operating levels will be investigated. A variety of different x-ray lines can be obtained by the simple interchange of anodes of different materials. Typical anodes are made from easily machined metals, or materials which are vacuum deposited onto a copper anode. Typically, a few microns of material is sufficient to stop 10 KV electrons without significantly decreasing the thermal conductivity through the anode. The small size and high brightness of this source make it useful for step and repeat exposures over several square centimeter areas, especially in a research laboratory environment. For an aluminum anode, the estimated Al-K x-ray flux at 10 cms from the source is 70 μW/cm 2

Artificial light at night confounds broad-scale habitat use by migrating birds

Science.gov (United States)

McLaren, James D.; Buler, Jeffrey J.; Schreckengost, Tim; Smolinsky, Jaclyn A.; Boone, Matthew; van Loon, E. Emiel; Dawson, Deanna K.; Walters, Eric L.

2018-01-01

With many of the world's migratory bird populations in alarming decline, broad-scale assessments of responses to migratory hazards may prove crucial to successful conservation efforts. Most birds migrate at night through increasingly light-polluted skies. Bright light sources can attract airborne migrants and lead to collisions with structures, but might also influence selection of migratory stopover habitat and thereby acquisition of food resources. We demonstrate, using multi-year weather radar measurements of nocturnal migrants across the northeastern U.S., that autumnal migrant stopover density increased at regional scales with proximity to the brightest areas, but decreased within a few kilometers of brightly-lit sources. This finding implies broad-scale attraction to artificial light while airborne, impeding selection for extensive forest habitat. Given that high-quality stopover habitat is critical to successful migration, and hindrances during migration can decrease fitness, artificial lights present a potentially heightened conservation concern for migratory bird populations.

Modeling of Diamond Field-Emitter-Arrays for high brightness photocathode applications

Science.gov (United States)

Kwan, Thomas; Huang, Chengkun; Piryatinski, Andrei; Lewellen, John; Nichols, Kimberly; Choi, Bo; Pavlenko, Vitaly; Shchegolkov, Dmitry; Nguyen, Dinh; Andrews, Heather; Simakov, Evgenya

2017-10-01

We propose to employ Diamond Field-Emitter-Arrays (DFEAs) as high-current-density ultra-low-emittance photocathodes for compact laser-driven dielectric accelerators capable of generating ultra-high brightness electron beams for advanced applications. We develop a semi-classical Monte-Carlo photoemission model for DFEAs that includes carriers' transport to the emitter surface and tunneling through the surface under external fields. The model accounts for the electronic structure size quantization affecting the transport and tunneling process within the sharp diamond tips. We compare this first principle model with other field emission models, such as the Child-Langmuir and Murphy-Good models. By further including effects of carrier photoexcitation, we perform simulations of the DFEAs' photoemission quantum yield and the emitted electron beam. Details of the theoretical model and validation against preliminary experimental data will be presented. Work ssupported by LDRD program at LANL.

A Next Generation Light Source Facility at LBNL

Energy Technology Data Exchange (ETDEWEB)

Corlett, J.N.; Austin, B.; Baptiste, K.M.; Byrd, J.M.; Denes, P.; Donahue, R.; Doolittle, L.; Falcone, R.W.; Filippetto, D.; Fournier, S.; Li, D.; Padmore, H.A.; Papadopoulos, C.; Pappas, C.; Penn, G.; Placidi, M.; Prestemon, S.; Prosnitz, D.; Qiang, J.; Ratti, A.; Reinsch, M.; Sannibale, F.; Schlueter, R.; Schoenlein, R.W.; Staples, J.W.; Vecchione, T.; Venturini, M.; Wells, R.; Wilcox, R.; Wurtele, J.; Charman, A.; Kur, E.; Zholents, A.A.

2011-03-23

The Next Generation Light Source (NGLS) is a design concept, under development at LBNL, for a multibeamline soft x-ray FEL array powered by a ~;;2 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. The CW superconducting linear accelerator is supplied by a high-brightness, highrepetition- rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for EEHG, HGHG, SASE, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format, with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds.

New Light on the Mind’s Eye : The Pupillary Light Response as Active Vision

NARCIS (Netherlands)

Mathôt, Sebastiaan; Van der Stigchel, Stefan

2015-01-01

The eye’s pupils constrict (shrink) in brightness and dilate (expand) in darkness. The pupillary light response was historically considered a low-level reflex without any cognitive component. Here, we review recent studies that have dramatically changed this view: The light response depends not only

WINDII airglow observations of wave superposition and the possible association with historical "bright nights"

Science.gov (United States)

Shepherd, G. G.; Cho, Y.-M.

2017-07-01

Longitudinal variations of airglow emission rate are prominent in all midlatitude nighttime O(1S) lower thermospheric data obtained with the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS). The pattern generally appears as a combination of zonal waves 1, 2, 3, and 4 whose phases propagate at different rates. Sudden localized enhancements of 2 to 4 days duration are sometimes evident, reaching vertically integrated emission rates of 400 R, a factor of 10 higher than minimum values for the same day. These are found to occur when the four wave components come into the same phase at one longitude. It is shown that these highly localized longitudinal maxima are consistent with the historical phenomena known as "bright nights" in which the surroundings of human dark night observers were seen to be illuminated by this enhanced airglow.Plain Language SummaryFor centuries, going back to the Roman era, people have recorded experiences of brightened skies during the night, called "bright nights." Currently, scientists study airglow, an emission of light from the high atmosphere, 100 km above us. Satellite observations of a green airglow have shown that it consists of waves 1, 2, 3, and 4 around the earth. It happens that when the peaks of the different waves coincide there is an airglow brightening, and this article demonstrates that this event produces a bright night. The modern data are shown to be entirely consistent with the historical observations.

Light therapy: Methodological issues from an engineering perspective.

NARCIS (Netherlands)

Joost van Hoof; Aries; MD E.J.M. Wouters; Van Someren; Schoutens; Westerlaken; Aarts; Sinoo

2011-01-01

Light therapy is increasingly administered and studied as a non-pharmacologic treatment for a variety of health-related problems. Light therapy comes in a variety of ways, ranging from being exposed to daylight to being exposed to light from light boxes and ambient bright light. Light therapy is an

Design and construction of a DC high-brightness laser driven electron gun

Science.gov (United States)

Zhao, K.; Geng, R. L.; Wang, L. F.; Zhang, B. C.; Yu, J.; Wang, T.; Wu, G. F.; Song, J. H.; Chen, J. E.

1996-02-01

A DC high-brightness laser driven photoemissive electron gun is being developed at Peking University, in order to produce 50-100 ps electron bunches of high quality. The gun consists of a photocathode preparation chamber and a DC acceleration cavity. Different ways of fabricating photocathodes, such as chemical vapor deposition, ion beam implantation and ion beam enhanced deposition, can be adopted. The acceleration gap is designed with the aid of simulation codes EGUN and POISSON. The laser system is a mode-locked Nd-YAG oscillator proceeded by an amplifier at 10 Hz repetition rate, which can deliver three different wavelengths (1064/532/266 nm). The combination of a superconducting cavity with the photocathode preparation chamber is also discussed in this paper.

HIGH ENERGY, HIGH BRIGHTNESS X-RAYS PRODUCED BY COMPTON BACKSCATTERING AT THE LIVERMORE PLEIADES FACILITY

International Nuclear Information System (INIS)

Tremaine, A M; Anderson, S G; Betts, S; Crane, J; Gibson, D J; Hartemann, F V; Jacob, J S; Frigola, P; Lim, J; Rosenzweig, J; Travish, G

2005-01-01

PLEIADES (Picosecond Laser Electron Interaction for the Dynamic Evaluation of Structures) produces tunable 30-140 keV x-rays with 0.3-5 ps pulse lengths and up to 10 7 photons/pulse by colliding a high brightness electron beam with a high power laser. The electron beam is created by an rf photo-injector system, accelerated by a 120 MeV linac, and focused to 20 (micro)m with novel permanent magnet quadrupoles. To produce Compton back scattered x-rays, the electron bunch is overlapped with a Ti:Sapphire laser that delivers 500 mJ, 100 fs, pulses to the interaction point. K-edge radiography at 115 keV on Uranium has verified the angle correlated energy spectrum inherent in Compton scattering and high-energy tunability of the Livermore source. Current upgrades to the facility will allow laser pumping of targets synchronized to the x-ray source enabling dynamic diffraction and time-resolved studies of high Z materials. Near future plans include extending the radiation energies to >400 keV, allowing for nuclear fluorescence studies of materials

Multistage morphological segmentation of bright-field and fluorescent microscopy images

Science.gov (United States)

Korzyńska, A.; Iwanowski, M.

2012-06-01

This paper describes the multistage morphological segmentation method (MSMA) for microscopic cell images. The proposed method enables us to study the cell behaviour by using a sequence of two types of microscopic images: bright field images and/or fluorescent images. The proposed method is based on two types of information: the cell texture coming from the bright field images and intensity of light emission, done by fluorescent markers. The method is dedicated to the image sequences segmentation and it is based on mathematical morphology methods supported by other image processing techniques. The method allows for detecting cells in image independently from a degree of their flattening and from presenting structures which produce the texture. It makes use of some synergic information from the fluorescent light emission image as the support information. The MSMA method has been applied to images acquired during the experiments on neural stem cells as well as to artificial images. In order to validate the method, two types of errors have been considered: the error of cell area detection and the error of cell position using artificial images as the "gold standard".

Night Sky Brightness Measurement by the Public through a Mobile Phone App

Science.gov (United States)

Kamegai, Kazuhisa; Tsukada, Ken; Inoue, Hiroki

2015-08-01

The darkness of night sky is important naturally for astronomy researchers, and also for the public people. Particularly, it is meaningful for those who begin to have an interest in gazing stars. Some previous studies suggest that light pollution may affect human health and ecosystem in various ways. Furthermore, it causes a lot of waste of electric energy for lighting.In Japan, the night sky brightness had been measured by Ministry of Environment for a few decades. Recently some global efforts have been also conducted. However the number of measured position is limited because the measurement needs some apparatus and takes long time.Here we show a result of quick and easy measurements of night sky brightness by the public people through a mobile phone app. The measurements were conducted in cooperation between some members of the Tenpla project and a weather forecasting company. The app has been developed by the company and has been installed by over 6.5 million people, which allow us to get a large number of data. Our purposes are (1) making map of night sky brightness all over Japan and (2) providing an opportunity to enjoy gazing star for those who are not usually interested in astronomy.As an interactive function of the app, we put a questionnaire of four choices in which we ask users how many stars are visible in a part of the constellation of Orion. When users answer the question, we get the answer and the position where they are. Depending on the answer, we can roughly recognize the sky brightness of the position.We opened the measurements for several nights. As a result, we could get 4000 - 5000 data all over the country per night. The map of each night is a snapshot of sky brightness of the night including effect of the weather. For example we can recognize that the sky is getting darker as a function of distance from the metropolitan area of Tokyo. We will show the detail results in the presentation.

1.9 W yellow, CW, high-brightness light from a high efficiency semiconductor laser-based system

DEFF Research Database (Denmark)

Hansen, Anders Kragh; Christensen, Mathias; Noordegraaf, Danny

2017-01-01

Semiconductor lasers are ideal sources for efficient electrical-to-optical power conversion and for many applications where their small size and potential for low cost are required to meet market demands. Yellow lasers find use in a variety of bio-related applications, such as photocoagulation......, imaging, flow cytometry, and cancer treatment. However, direct generation of yellow light from semiconductors with sufficient beam quality and power has so far eluded researchers. Meanwhile, tapered semiconductor lasers at near-infrared wavelengths have recently become able to provide neardiffraction...... power in just 60 seconds. An advantage of using a single pass configuration, rather than an external cavity configuration, is increased stability towards external perturbations. For example, stability to fluctuating case temperature over a 30 K temperature span has been demonstrated. The combination...

Dawn song in natural and artificial continuous day: Light pollution affects songbirds at high latitudes.

Science.gov (United States)

Derryberry, Elizabeth P

2017-10-01

In Focus: Da Silva, A., & Kempenaers, B. (2017). Singing from North to South: Latitudinal variation in timing of dawn singing under natural and artificial light conditions. Journal of Animal Ecology, 86, 1286-1297. doi: 10.1111/1365-2656.12739 Satellite images of the world at night show bright dots connected by glowing lines crisscrossing the globe. As these connect-the-dots become brighter and expand into more and more remote regions, much of the flora and fauna of the world are experiencing evolutionarily unprecedented levels of light at night. Light cues are essential to most physiological and behavioural processes, and so the need to measure the effects of light pollution on these processes is critical. In this issue, Da Silva and Kempenaers take on this task using an important reproductive behaviour in songbirds-dawn song. The geographic, temporal and taxonomic breadth of sampling in this study allows for a close examination of a potentially complex interaction between light pollution and natural variation in the behaviour of dawn singing across latitude, season and species. Their extensive dataset highlights complexity in how songbirds respond to light pollution. Although light pollution has a strong effect on the timing of dawn song, not all songbirds respond the same way to light pollution, and the effects of light pollution vary with changes in natural light levels. Early dawn singers show more flexibility in the timing of dawn song across the season and across latitudes than late dawn singers, and also appear less affected by light pollution at high latitudes than are late dawn singers. These findings suggest that not all songbirds are responding to artificial continuous daylight as they do to natural continuous daylight, highlighting the general need to measure the fitness effects of light pollution. © 2017 The Author. Journal of Animal Ecology © 2017 British Ecological Society.

High-speed photometry of the dwarf nova Z Cha in quiescence

International Nuclear Information System (INIS)

Wood, Janet; Horne, Keith; Berriman, Graham; O'Donoghue, Darragh; Warner, Brian

1986-01-01

High-speed white light photometry of the cataclysmic variable star Z Cha is used to study the structure of the system and to derive the properties of its components. The white dwarf and bright spot eclipse timings require a mass ratio, q=Msub(R)/Msub(WD) of 0.146 0 .9>i>81 0 .6. The infalling stream passes through the light centre of the bright spot. If the central luminous object is the white dwarf its mass is 0.54+-0.01 Msolar mass which corresponds to a secondary star mass of 0.081+-0.003 Msolar mass. Agreement between colour and brightness temperatures for the white dwarf and bright spot provide a rough confirmation of the 97 pc distance. (author)

Strategy Guideline. High Performance Residential Lighting

Energy Technology Data Exchange (ETDEWEB)

Holton, J. [IBACOS, Inc., Pittsburgh, PA (United States)

2012-02-01

This report has been developed to provide a tool for the understanding and application of high performance lighting in the home. The strategies featured in this guide are drawn from recent advances in commercial lighting for application to typical spaces found in residential buildings. This guide offers strategies to greatly reduce lighting energy use through the application of high quality fluorescent and light emitting diode (LED) technologies. It is important to note that these strategies not only save energy in the home but also serve to satisfy the homeowner’s expectations for high quality lighting.

Visible Color and Photometry of Bright Materials on Vesta

Science.gov (United States)

Schroder, S. E.; Li, J. Y.; Mittlefehldt, D. W.; Pieters, C. M.; De Sanctis, M. C.; Hiesinger, H.; Blewett, D. T.; Russell, C. T.; Raymond, C. A.; Keller, H. U.

2012-01-01

The Dawn Framing Camera (FC) collected images of the surface of Vesta at a pixel scale of 70 m in the High Altitude Mapping Orbit (HAMO) phase through its clear and seven color filters spanning from 430 nm to 980 nm. The surface of Vesta displays a large diversity in its brightness and colors, evidently related to the diverse geology [1] and mineralogy [2]. Here we report a detailed investigation of the visible colors and photometric properties of the apparently bright materials on Vesta in order to study their origin. The global distribution and the spectroscopy of bright materials are discussed in companion papers [3, 4], and the synthesis results about the origin of Vestan bright materials are reported in [5].

Status of light ion inertial fusion research at NRL

International Nuclear Information System (INIS)

Cooperstein, G.; Barker, R.J.; Colombant, D.G.; Goldstein, S.A.; Meger, R.A.; Mosher, D.; Neri, J.M.; Ottinger, P.F.

1984-01-01

This chapter reports on the use of high-brightness proton beams, extracted from axial pinch-reflex diodes mounted on the Naval Research Laboratory (NRL) Gamble II generator, to study light ion inertial fusion. Topics covered include the modular approach, ion beam brightness studies, light-ion beam transport, final focusing, the single diode approach, the inductive storage approach, an energy loss experiment, and future plans. Analysis of a modular inertial confinement fusion (ICF) system using axial pinch-reflex diodes shows that an operational window for transport of light-ion species exists. A proof-of-principle experiment for the required final focusing cell was conducted on Gamble II. Preliminary experiments using vacuum inductive storage and plasma opening switches have demonstrated factorof-three pulse compressions, with corresponding power and voltage multiplications for pulse durations of interest to PBFA II. The stopping power of deuterons in hot plasmas was measured in other experiments. It is demonstrated that about 40% enhancement in stopping power over that in cold targets when the deuteron beam is focused on the target to about .25 MA/cm 2 . Includes 6 diagrams

Measuring brightness temperature distributions of plasma bunches

International Nuclear Information System (INIS)

Kirko, V.I.; Stadnichenko, I.A.

1981-01-01

The possibility of restoration of brightness temperature distribution along plasma jet on the base of a simple ultra high- speed photography and subsequent photometric treatment is shown. The developed technique has been applied for finding spectral radiation intensity and brightness temperature of plasma jets of a tubular gas-cumulative charge and explosive plasma compressor. The problem of shock wave front has been successfully solved and thus distribution of above parameters beginning from the region preceeding the shock wave has been obtained [ru

Efficient fluorescence/phosphorescence white organic light-emitting diodes with ultra high color stability and mild efficiency roll-off

Science.gov (United States)

Du, Xiaoyang; Tao, Silu; Huang, Yun; Yang, Xiaoxia; Ding, Xulin; Zhang, Xiaohong

2015-11-01

Efficient fluorescence/phosphorescence hybrid white organic light-emitting diodes (OLEDs) with single doped co-host structure have been fabricated. Device using 9-Naphthyl-10 -(4-triphenylamine)anthrancene as the fluorescent dopant and Ir(ppy)3 and Ir(2-phq)3 as the green and orange phosphorescent dopants show the luminous efficiency of 12.4% (17.6 lm/W, 27.5 cd/A) at 1000 cd/m2. Most important to note that the efficiency-brightness roll-off of the device was very mild. With the brightness rising up to 5000 and 10 000 cd/m2, the efficiency could be kept at 11.8% (14.0 lm/W, 26.5 cd/A) and 11.0% (11.8 lm/W, 25.0 cd/A). The Commission Internationale de L'Eclairage (CIE) coordinates and color rending index (CRI) were measured to be (0.45, 0.48) and 65, respectively, and remained the same in a large range of brightness (1000-10 000 cd/m2), which is scarce in the reported white OLEDs. The performance of the device at high luminance (5000 and 10 000 cd/m2) was among the best reported results including fluorescence/phosphorescence hybrid and all-phosphorescent white OLEDs. Moreover, the CRI of the white OLED can be improved to 83 by using a yellow-green emitter (Ir(ppy)2bop) in the device.

Is light pollution getting better or worse?

Science.gov (United States)

Kyba, Christopher C. M.

2018-04-01

Awareness of light pollution is spreading, but with changing lighting technologies, emissions are shifting to wavelengths our current measuring devices cannot assess well. Community involvement is essential to evaluate changes in sky brightness.

But for the Bad, There Would Not Be Good: Grounding Valence in Brightness through Shared Relational Structures

Science.gov (United States)

Lakens, Daniel; Semin, Gun R.; Foroni, Francesco

2012-01-01

Light and dark are used pervasively to represent positive and negative concepts. Recent studies suggest that black and white stimuli are automatically associated with negativity and positivity. However, structural factors in experimental designs, such as the shared opposition in the valence (good vs. bad) and brightness (light vs. dark) dimensions…

Analysis of insertion device magnet measurements for the Advanced Light Source

International Nuclear Information System (INIS)

Marks, S.; Humphries, D.; Kincaid, B.M.; Schlueter, R.; Wang, C.

1993-07-01

The Advanced Light Source (ALS), which is currently being commissioned at Lawrence Berkeley Laboratory, is a third generation light source designed to produce XUV radiation of unprecedented brightness. To meet the high brightness goal the storage ring has been designed for very small electron beam emittance and the undulators installed in the ALS are built to a high degree of precision. The allowable magnetic field errors are driven by electron beam and radiation requirements. Detailed magnetic measurements and adjustments are performed on each undulator to qualify it for installation in the ALS. The first two ALS undulators, IDA and IDB, have been installed. This paper describes the program of measurements, data analysis, and adjustments carried out for these two devices. Calculations of the radiation spectrum, based upon magnetic measurements, are included. Final field integral distributions are also shown. Good field integral uniformity has been achieved using a novel correction scheme, which is also described

Thin Film Packaging Solutions for High Efficiency OLED Lighting Products

Energy Technology Data Exchange (ETDEWEB)

None

2008-06-30

was characterized as having less than 10% change in transmission during the 15,000 hour test period; (3) demonstrated thin film encapsulation of a phosphorescent OLED device with 1,500 hours of lifetime at 60 C and 80% RH; (4) demonstrated that a thin film laminate encapsulation, in addition to the direct thin film deposition process, of a polymer OLED device was another feasible packaging strategy for OLED lighting. The thin film laminate strategy was developed to mitigate defects, demonstrate roll-to-roll process capability for high volume throughput (reduce costs) and to support a potential commercial pathway that is less dependent upon integrated manufacturing since the laminate could be sold as a rolled good; (5) demonstrated that low cost 'blue' glass substrates could be coated with a siloxane barrier layer for planarization and ion-protection and used in the fabrication of a polymer OLED lighting device. This study further demonstrated that the substrate cost has potential for huge cost reductions from the white borosilicate glass substrate currently used by the OLED lighting industry; (6) delivered four-square feet of white phosphorescent OLED technology, including novel high efficiency devices with 82 CRI, greater than 50 lm/W efficiency, and more than 1,000 hours lifetime in a product concept model shelf; (7) presented and or published more than twenty internal studies (for private use), three external presentations (OLED workshop-for public use), and five technology-related external presentations (industry conferences-for public use); and (8) issued five patent applications, which are in various maturity stages at time of publication. Delivery of thin film encapsulated white phosphorescent OLED lighting technology remains a challenging technical achievement, and it seems that commercial availability of thin, bright, white OLED light that meets market requirements will continue to require research and development effort. However, there will be

Bright point study

International Nuclear Information System (INIS)

Tang, F.; Harvey, K.; Bruner, M.; Kent, B.; Antonucci, E.

1982-01-01

Transition region and coronal observations of bright points by instruments aboard the Solar Maximum Mission and high resolution photospheric magnetograph observations on September 11, 1980 are presented. A total of 31 bipolar ephemeral regions were found in the photosphere from birth in 9.3 hours of combined magnetograph observations from three observatories. Two of the three ephemeral regions present in the field of view of the Ultraviolet Spectrometer-Polarimeter were observed in the C IV 1548 line. The unobserved ephemeral region was determined to be the shortest-lived (2.5 hr) and lowest in magnetic flux density (13G) of the three regions. The Flat Crystal Spectrometer observed only low level signals in the O VIII 18.969 A line, which were not statistically significant to be positively identified with any of the 16 ephemeral regions detected in the photosphere. In addition, the data indicate that at any given time there lacked a one-to-one correspondence between observable bright points and photospheric ephemeral regions, while more ephemeral regions were observed than their counterparts in the transition region and the corona

Scientific program of the Advanced Light Source at LBL

International Nuclear Information System (INIS)

Robinson, A.L.; Schlachter, A.S.

1991-10-01

Construction of the Advanced Light Source (ALS) at the Lawrence Berkeley Laboratory is nearing completion, with operation as a US Department of Energy national user facility scheduled to begin in the spring of 1993. Based on a low-emittance, 1.5-GeV electron storage ring with 10 long straight sections available for insertion devices and, initially, 24 bend-magnet ports, the ALS will be a third-generation source of soft x-ray and ultraviolet (collectively, the XUV) synchrotron radiation. Experimental facilities (insertion devices, beamlines, and end stations) will be developed and operated by participating research teams working with the ALS staff. The ability to exploit the high spectral brightness of the ALS was the main criterion for PRT selection. In the XUV spectral regions served by the ALS, a major benefit of high brightness will be the ability to achieve spatial resolution in the neighborhood of 200 angstroms in x-ray microscopy and holography and in spatially resolved spectroscopy. Other beneficiaries of high brightness include very-high-resolution spectroscopy, spectroscopy of dilute species, diffraction from very small samples, and time-resolved spectroscopy and diffraction

Low dimensional neutron moderators for enhanced source brightness

DEFF Research Database (Denmark)

Mezei, Ferenc; Zanini, Luca; Takibayev, Alan

2014-01-01

In a recent numerical optimization study we have found that liquid para-hydrogen coupled cold neutron moderators deliver 3–5 times higher cold neutron brightness at a spallation neutron source if they take the form of a flat, quasi 2-dimensional disc, in contrast to the conventional more voluminous...... for cold neutrons. This model leads to the conclusions that the optimal shape for high brightness para-hydrogen neutron moderators is the quasi 1-dimensional tube and these low dimensional moderators can also deliver much enhanced cold neutron brightness in fission reactor neutron sources, compared...... to the much more voluminous liquid D2 or H2 moderators currently used. Neutronic simulation calculations confirm both of these theoretical conclusions....

Search for high-energy neutrinos from bright GRBs with ANTARES

NARCIS (Netherlands)

Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M.C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Chiarusi, T.; Circella, M.; Coelho, J.A.B.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Deschamps, A.; De Bonis, G.; Distefano, C.; Di Palma, I.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; Elsässer, D.; Enzenhöfer, A.; Felis, I.; Fusco, L.A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Glotin, H.; Grégoire, T.; Gracia-Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A.J.; Hello, Y.; Hernández-Rey, J.J.; Hößl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C.W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J.A.; Mathieu, A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Nezri, E.; Pavalas, G.E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Roensch, K.; Sánchez-Losa, A.; Saldaña, M.; Salvadori, I.; Samtleben, D.F.E.; Sanguineti, M.; Sapienza, P.; Schnabel, J.; Schüssler, F.; Seitz, T.; Sieger, C.; Spurio, M.; Stolarczyk, T.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Tselengidou, M.; Turpin, D.; Tönnis, C.; Vallage, B.; Vallée, C.; Van Elewyck, V.; Vivolo, D.; Vizzocca, A.; Wagner, S.; Wilms, J.; Zornoza, J.D.; Zúñiga, J.

2017-01-01

Gamma-ray bursts are thought to be sites of hadronic acceleration, thus neutrinos are expected from the decay of charged particles, produced in pγ interactions. The methods and results of a search for muon neutrinos in the data of the ANTARES neutrino telescope from four bright GRBs (GRB 080916C,

A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

NARCIS (Netherlands)

Nijboer, T.C.W.; Nys, G.M.S.; van der Smagt, M.J.; de Haan, E.H.F.

2009-01-01

We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level

Survey and alignment for the Swiss Light Source

International Nuclear Information System (INIS)

Wei, F.Q.; Dreyer, K.; Fehlmann, U.; Pochon, J.L.; Wrulich, A.

1999-01-01

The Swiss Light Source (SLS) is a dedicated high brightness synchrotron light source currently under construction at the Paul Scherrer Institute (PSI) in Villigen. It will be commissioned in 2001. The accelerator complex includes a 2.4 GeV electron storage ring (SR) with 288 in circumference, a full energy injection booster synchrotron (Booster) and a 100 MeV linear pre-accelerator. The general alignment method and first results of the network measurements are presented. A laser tracker LTD500 is mainly adopted for network measurements and the alignment of storage ring components. (authors)

Adaptive Lighting Design – Staged Experiences of Light

DEFF Research Database (Denmark)

Petersen, Kjell Yngve; Søndergaard, Karin

in ways that meaningfully adapt. In the two installations, two different aspects are at play. In White Cube, the light colours are balanced. In White Box, the light follows the movements of the people in the space. In situations with several people occupying the same space, social relations become......Adaptive Lighting Design – Staged Experiences of Light The two installations, White Cube and White Box, enable experience-based studies as a form of perceptual activity, wherein lighting conditions are examined in a dialectical exchange between the system and the people participating. Adaptive...... lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. Software can be seen to bear a communicative aesthetic, where the relation of user situations and the design intentions are controlled...

Light Modulates Ocular Complications in an Albino Rat Model of Type 1 Diabetes Mellitus.

Science.gov (United States)

Andrawus, Elias; Veildbaum, Gizi; Zemel, Esther; Leibu, Rina; Perlman, Ido; Shehadeh, Naim

2017-07-01

The purpose of the study was to assess potential interactions of light exposure and hyperglycemia upon ocular complications in diabetic rats. Streptozotocin-induced (STZ-induced) diabetic rats ( N = 39) and non-diabetic rats ( N = 9) were distributed into eight groups according to the irradiance and color of the light phase during the 12/12-hour light/dark regime. Follow-up lasted 90 days and included assessment of cataract development and electroretinogram (ERG) recordings. Stress to the retina was also assessed by glial fibrillary acidic protein immunocytochemistry. Cataract development was fast in diabetic rats that were exposed to unattenuated white light or to bright colored lights during the light phase. Diabetic rats that were kept under attenuated brown or yellow light during the light phase exhibited slower rate of cataract development. Electroretinogram responses indicated very severe retinal damage in diabetic rats kept under bright colored lights in the blue-yellow range or bright white light during the light phase. Electroretinogram damage was milder in rats kept under bright red light or attenuated yellow or brown light during the light phase. Glial fibrillary acidic protein expression in retinal Müller cells was consistent with ERG assessment of retinal damage. Attenuating white light and filtering out short wavelengths have a protective effect on the eyes of diabetic rats as evident by slower rate of cataract formation and a smaller degree of retinal damage. Our findings suggest that special glasses attenuating light exposure and filtering out short wavelengths (400-530 nm) may be beneficial for diabetic patients.

Diode lasers optimized in brightness for fiber laser pumping

Science.gov (United States)

Kelemen, M.; Gilly, J.; Friedmann, P.; Hilzensauer, S.; Ogrodowski, L.; Kissel, H.; Biesenbach, J.

2018-02-01

In diode laser applications for fiber laser pumping and fiber-coupled direct diode laser systems high brightness becomes essential in the last years. Fiber coupled modules benefit from continuous improvements of high-power diode lasers on chip level regarding output power, efficiency and beam characteristics resulting in record highbrightness values and increased pump power. To gain high brightness not only output power must be increased, but also near field widths and far field angles have to be below a certain value for higher power levels because brightness is proportional to output power divided by beam quality. While fast axis far fields typically show a current independent behaviour, for broadarea lasers far-fields in the slow axis suffer from a strong current and temperature dependence, limiting the brightness and therefore their use in fibre coupled modules. These limitations can be overcome by carefully optimizing chip temperature, thermal lensing and lateral mode structure by epitaxial and lateral resonator designs and processing. We present our latest results for InGaAs/AlGaAs broad-area single emitters with resonator lengths of 4mm emitting at 976nm and illustrate the improvements in beam quality over the last years. By optimizing the diode laser design a record value of the brightness for broad-area lasers with 4mm resonator length of 126 MW/cm2sr has been demonstrated with a maximum wall-plug efficiency of more than 70%. From these design also pump modules based on 9 mini-bars consisting of 5 emitters each have been realized with 360W pump power.

Determination atmospheric conditions by evaluating clearness index, turbidity and brightness of the sky

International Nuclear Information System (INIS)

Kandilli, C.

2005-01-01

There are fifteen different sky types which range from totally overcast sky to low turbidity clear sky have been defined by CIE (International Commission on Illumination). For the applications of solar energy engineering and day lighting purposes, it has a great importance to determine the physical characteristics of atmosphere and the sky type. The most important parameters which define the sky type are clearness index, turbidity and brightness. In this study, the parameters of clearness index, turbidity and brightness of the sky belong to Izmir was calculated and their relations with solar radiation and its components were represented according to 10 years data (1994-2004) of meteorology station of Ege University Solar Energy Institute. In this study, clearness index, turbidity, sky clearness and brightness were evaluated to put forward the effects of the these parameters on the atmospheric condition for designing and engineering purposes

Exploring the Impact of Natural Light Exposure on Sleep of Healthy Older Adults: A Field Study

Directory of Open Access Journals (Sweden)

Mariëlle P. J. Aarts

2018-05-01

Full Text Available Studies among people with dementia demonstrated that the sleep quality and rhythm improves significantly when people are exposed to ambient bright light. Since almost half of the healthy older people also indicate to suffer from chronic sleep disorders, the question arises whether ambient bright light can be beneficial to healthy older people. Particularly the effect on sleep/wake rhythm in relation to the exposure to natural light is the focus. It was hypothesised that the sleep quality would be worse in winter due to a lower daylight dose than in summer due to the lower illuminance and exposure duration. A field study was conducted to examine the relationship between daylight exposure and sleep quality in 14 healthy older adults living independently in their own dwellings in the Netherlands. All participants were asked to take part of the study both during the summer period as well as during the winter period. Therefore, they had to wear an actigraph for five consecutive days which measured sleep, activity and light exposure. Results confirmed that people were significantly longer exposed to high illumination levels (>1000 lx in summer than in winter. Sleep quality measures, however, did not differ significantly between summer and winter. A significant, positive correlation was found between exposure duration to high illuminance from daylight during the day and the sleep efficiency the following night in summer, implying that being exposed to high illuminance for a longer time period has a positive effect on sleep efficiency for the individual data. There was also a tendency of less frequent napping in case of longer exposure duration to light for both seasons. Sleep quality does not differ between summer and winter but is related to the duration of the exposure to bright light the day prior to the night.

InP/ZnS nanocrystals for colour conversion in white light emitting diodes

DEFF Research Database (Denmark)

Shirazi, Roza

In this work a comprehensive study of a colloidal InP/ZnS nanocrystals (NC) as the colour conversion material for white light emitting diodes (WLED) is shown. Studied nanocrystals were synthesised by wet chemistry using one pot, hot injection method. A quantum efficiency (QE) of photoluminescence......, radiative and non-radiative recombination rates were determined and QE of 63% for the population of NCs that emit light was derived. A search for source of exciton losses in bright nanocrystals temperature resolved TRPL was studied and it revealed carrier trapping most likely at core-shell interface as well...... as at the surface and which competes with bright and dark exciton states. A presence of long-lived dark excitons and trapped charges lead to strong Auger recombination at high (relative to the trapping times) excitation. A colour conversion efficiency of the nanocrystals upon light absorption and in a process...

Advanced laser technologies for high-brightness photocathode electron gun

International Nuclear Information System (INIS)

Tomizawa, Hiromitsu

2012-01-01

A laser-excited photocathode RF gun is one of the most reliable high-brightness electron beam sources for XFELs. Several 3D laser shaping methods have been developed as ideal photocathode illumination sources at SPring-8 since 2001. To suppress the emittance growth caused by nonlinear space-charge forces, the 3D cylindrical UV-pulse was optimized spatially as a flattop and temporally as squarely stacked chirped pulses. This shaping system is a serial combination of a deformable mirror that adaptively shapes the spatial profile with a genetic algorithm and a UV-pulse stacker that consists of four birefringent α-BBO crystal rods for temporal shaping. Using this 3D-shaped pulse, a normalized emittance of 1.4 πmm mrad was obtained in 2006. Utilizing laser's Z-polarization, Schottky-effect-gated photocathode gun was proposed in 2006. The cathode work functions are reduced by a laser-induced Schottky effect. As a result of focusing a radially polarized laser pulse with a hollow lens in vacuum, the Z-field (Z-polarization) is generated at the cathode. (author)

Advanced Laser Technologies for High-brightness Photocathode Electron Gun

Science.gov (United States)

Tomizawa, Hiromitsu

A laser-excited photocathode RF gun is one of the most reliable high-brightness electron beam sources for XFELs. Several 3D laser shaping methods have been developed as ideal photocathode illumination sources at SPring-8 since 2001. To suppress the emittance growth caused by nonlinear space-charge forces, the 3D cylindrical UV-pulse was optimized spatially as a flattop and temporally as squarely stacked chirped pulses. This shaping system is a serial combination of a deformable mirror that adaptively shapes the spatial profile with a genetic algorithm and a UV-pulse stacker that consists of four birefringent α-BBO crystal rods for temporal shaping. Using this 3D-shaped pulse, a normalized emittance of 1.4 π mm mrad was obtained in 2006. Utilizing laser's Z-polarization, Schottky-effect-gated photocathode gun was proposed in 2006. The cathode work functions are reduced by a laser-induced Schottky effect. As a result of focusing a radially polarized laser pulse with a hollow lens in vacuum, the Z-field (Z-polarization) is generated at the cathode.

InGaN micro-LED-pillar as the building block for high brightness emitters

KAUST Repository

Shen, Chao; Cha, Dong Kyu; Ng, Tien Khee; Ooi, Boon S.; Yang, Yang

2013-01-01

In summary, we confirmed the improved electrical and optical characteristics, with reduced efficiency droop in InGaN μLED-pillars when these devices were scaled down in size. We demonstrated that strain relief contributed to further improvement in EQE characteristics in small InGaN μLED-pillars (D < 50 μm), apart from the current spreading effect. The μLED-pillar can be deployed as the building block for large effective-area, high brightness emitter. © 2013 IEEE.

: Light Steering Projection Systems and Attributes for HDR Displays

KAUST Repository

Damberg, Gerwin

2017-06-02

New light steering projectors in cinema form images by moving light away from dark regions into bright areas of an image. In these systems, the peak luminance of small features can far exceed full screen white luminance. In traditional projectors where light is filtered or blocked in order to give shades of gray (or colors), the peak luminance is fixed. The luminance of chromatic features benefit in the same way as white features, and chromatic image details can be reproduced at high brightness leading to a much wider overall color gamut coverage than previously possible. Projectors of this capability are desired by the creative community to aid in and enhance storytelling. Furthermore, reduced light source power requirements of light steering projectors provide additional economic and environmental benefits. While the dependency of peak luminance level on (bright) image feature size is new in the digital cinema space, display technologies with identical characteristics such as OLED, LED LCD and Plasma TVs are well established in the home. Similarly, direct view LED walls are popular in events, advertising and architectural markets. To enable consistent color reproduction across devices in today’s content production pipelines, models that describe modern projectors and display attributes need to evolve together with HDR standards and available metadata. This paper is a first step towards rethinking legacy display descriptors such as contrast, peak luminance and color primaries in light of new display technology. We first summarize recent progress in the field of light steering projectors in cinema and then, based on new projector and existing display characteristics propose the inclusion of two simple display attributes: Maximum Average Luminance and Peak (Color) Primary Luminance. We show that the proposed attributes allow a better prediction of content reproducibility on HDR displays. To validate this assertion, we test professional content on a commercial HDR

The influence of ambient light on the driver

Science.gov (United States)

Klinger, Karsten D.; Lemmer, Uli

2008-04-01

Increasingly, cars are fitted with interior ambient lighting which is switched on while driving. This special kind of interior light emphasizes the interior design of the car, it makes a car look special and gives the buyers a new option to personalize their automobiles. But how does ambient interior light influence the driver? We conducted a series of over 50 tests to study the influence of interior ambient light on contrast perception under different illumination levels, colors and positions of the illuminated areas. Our tests show that in many cases the ambient lighting can improve the visual contrast for seeing objects in the headlamp beam. But the test persons mentioned that the tested brightness looked too bright and that they felt glared. The measured values instead proved that no disability glare exists. Therefore, provided that the drivers can adjust the intensity of the ambient light to avoid glare, the ambient light has no negative effect on the drivers' contrast perception.

Stability of the nine sky quality meters in the Dutch night sky brightness monitoring network.

Science.gov (United States)

den Outer, Peter; Lolkema, Dorien; Haaima, Marty; van der Hoff, Rene; Spoelstra, Henk; Schmidt, Wim

2015-04-22

In the context of monitoring abundance of artificial light at night, the year-to-year stability of Sky Quality Meters (SQMs) is investigated by analysing intercalibrations derived from two measurement campaigns that were held in 2011 and 2012. An intercalibration comprises a light sensitivity factor and an offset for each SQM. The campaigns were concerned with monitoring measurements, each lasting one month. Nine SQMs, together forming the Night Sky Brightness Monitoring network (MHN) in The Netherlands, were involved in both campaigns. The stability of the intercalibration of these instruments leads to a year-to-year uncertainty (standard deviation) of 5% in the measured median luminance occurring at the MHN monitoring locations. For the 10-percentiles and 90-percentiles, we find 8% and 4%, respectively. This means that, for urban and industrial areas, changes in the sky brightness larger than 5% become detectable. Rural and nature areas require an 8%-9% change of the median luminance to be detectable. The light sensitivety agrees within 8% for the whole group of SQMs.

Improvement of white organic light emitting diode performances by an annealing process

International Nuclear Information System (INIS)

Sepeai, Suhaila; Salleh, Muhamad Mat; Yahaya, Muhammad; Umar, Akrajas Ali

2009-01-01

White organic light emitting diode (OLED) devices with the structure ITO/PHF:rubrene/Al, in which PHF (poly(9,9-di-n-hexylfluorenyl-2,7-diyl)) is used as blue light emitting host and rubrene (5,6,11,12-tetraphenylnapthacene) as an orange dye dopant, have been fabricated. Indium tin oxide (ITO) coated-glass and aluminium were used as anode and cathode, respectively. The devices were fabricated with various rubrene-dopant to obtain a white light emission. The OLED device that composed of several concentrations of rubrene-doped PHF film was prepared in this study. It was found that the concentration of rubrene in the PHF-rubrene thin film matrix plays a key role in producing the white color emission. In a typical result, the device composed of 0.06 wt.% rubrene-dopant produced the white light emission with the Commission Internationale de L'Eclairage (CIE) coordinate of (0.30,0.33). The turn-on voltage and the brightness were found to be as low as 14.0 V and as high as 6540 cd/m 2 , respectively. The annealing technique at relatively low temperature (50 o C, 100 o C, and 150 o C) was then used to optimize the performance of the device. In a typical result, the turn-on voltage of the device could be successfully reduced and the brightness could be increased using the annealing technique. At an optimum condition, for example, annealed at 150 o C, the turn-on voltage as low as 8.0 V and the brightness as high as 9040 cd/m 2 were obtained. The mechanism for the improvement of the device performance upon annealing will be discussed.

Algorithm to illustrate context using dynamic lighting effects

Science.gov (United States)

John, Roshy M.; Balasubramanian, T.

2007-09-01

With the invention of Ultra-Bright LED, solid state lighting has come to something which is much more efficient and energy saving when compared to conventional incandescent or fluorescent lighting. With the use of proper driver electronics now a days it is possible to install solid state lighting systems with the cost same as that of any other lighting technology. This paper is a part of the research project we are doing in our lab, which deals with using ultra bright LEDs of different colors for lighting applications. The driver electronics are made in such a way that, the color and brightness of the lights will change according to context. For instance, if one of the users is reading a story or listening to music in a Personal Computer or in a hand held device such as a PDA, the lighting systems and the HVAC (Heating Ventilation Air-conditioning) systems will change dramatically according to the content of the story or the music. The vulnerability of solid-state lighting helps to accomplish such an effect. Such a type of system will help the reader to feel the story mentally and physically as well. We developed complete driver electronics for the system using multiple microcomputers and a full software suite which uses complex algorithms to decode the context from text or music and synchronize it to lighting and HVAC information. The paper also presents some case-study statistics which shows the advantage of using the system to teach kindergarten children, deaf and dumb children and for language learning classes.

Solar flare effects on the zodiacal light

International Nuclear Information System (INIS)

Misconi, N.Y.

1975-01-01

An observational and theoretical study was carried out of possible solar flare effects on the zodiacal light. A total of 38 nights (February, March and April 1966, March 1967, and March 1968) of ground based observations, which were taken from Mt. Haleakala, Hawaii by Weinberg, were searched for solar flare effects. No changes were found in the shape of the main cone of the zodiacal light at elongations greater than 23 degrees from the sun to a limit of approximately 20 S 10 (V) units, and none were found in the level of brightness from night to night to a limit of approximately 100 S 10 (V) units. The earlier reported enhancement in the zodiacal light due to a large solar flare by Blackwell and Ingham (1961) is considered doubtful for two reasons: probable contamination of their observations by enhanced atmospheric emission, and detailed geometry of that event shows that it is unlikely that the plasma/dust interaction could have caused a 40 percent enhancement in the zodiacal light. Whether or not the plasma/dust interaction can be effective in causing a brightness change, a knowledge of the brightness contribution along the lines of sight and as a function of heliocentric distance is needed. For this purpose models of dielectric and metallic particles with spatial distribution of the form r/sup -ν/, ν = 0,1,2, and size distribution of the form a/sup -p/, p = 2.5,4, were computed using the Mie scattering theory. Dynamical processes affecting the dust particle's heliocentric orbit were considered in relation to brightness changes

Recent advances in light outcoupling from white organic light-emitting diodes

Science.gov (United States)

Gather, Malte C.; Reineke, Sebastian

2015-01-01

Organic light-emitting diodes (OLEDs) have been successfully introduced to the smartphone display market and have geared up to become contenders for applications in general illumination where they promise to combine efficient generation of white light with excellent color quality, glare-free illumination, and highly attractive designs. Device efficiency is the key requirement for such white OLEDs, not only from a sustainability perspective, but also because at the high brightness required for general illumination, losses lead to heating and may, thus, cause rapid device degradation. The efficiency of white OLEDs increased tremendously over the past two decades, and internal charge-to-photon conversion can now be achieved at ˜100% yield. However, the extraction of photons remains rather inefficient (typically physics of outcoupling in white OLEDs and review recent progress toward making light extraction more efficient. We describe how structures that scatter, refract, or diffract light can be attached to the outside of white OLEDs (external outcoupling) or can be integrated close to the active layers of the device (internal outcoupling). Moreover, the prospects of using top-emitting metal-metal microcavity designs for white OLEDs and of tuning the average orientation of the emissive molecules within the OLED are discussed.

Adaptive Lighting

DEFF Research Database (Denmark)

Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

2015-01-01

the investigations of lighting scenarios carried out in two test installations: White Cube and White Box. The test installations are discussed as large-scale experiential instruments. In these test installations we examine what could potentially occur when light using LED technology is integrated and distributed......Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... differently into an architectural body. We also examine what might occur when light is dynamic and able to change colour, intensity and direction, and when it is adaptive and can be brought into interaction with its surroundings. In short, what happens to an architectural space when artificial lighting ceases...

Measuring the color and brightness of artificial sky glow from cities using an all-sky imaging system calibrated with astronomical methods in the Johnson-Cousins B and V photometric systems

Science.gov (United States)

Pipkin, Ashley; Duriscoe, Dan M.; Lughinbuhl, Christian

2017-01-01

Artificial light at night, when observed at some distance from a city, results in a dome of sky glow, brightest at the horizon. The spectral power distribution of electric light utilized will determine its color of the light dome and the amount of light will determine its brightness. Recent outdoor lighting technologies have included blue-rich light emitting diode (LED) sources that may increase the relative amount of blue to green light in sky glow compared to typical high pressure sodium (HPS) sources with warmer spectra. Measuring and monitoring this effect is important to the preservation of night sky visual quality as seen from undeveloped areas outside the city, such as parks or other protected areas, since the dark-adapted human eye is more sensitive to blue and green. We present a method using a wide field CCD camera which images the entire sky in both Johnson V and B photometric bands. Standard stars within the images are used for calibration. The resulting all-sky brightness maps, and a derived B-V color index map, provide a means to assess and track the impact of specific outdoor lighting practices. We also present example data from several cities, including Las Vegas, Nevada, Flagstaff, Arizona, and Cheyenne, Wyoming.

LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

International Nuclear Information System (INIS)

Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua

2014-01-01

Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ( f licker ) of stars can be used to measure log g to a high accuracy of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T eff = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested

Large-area and bright pulsed electroluminescence in monolayer semiconductors

KAUST Repository

Lien, Der-Hsien; Amani, Matin; Desai, Sujay B.; Ahn, Geun Ho; Han, Kevin; He, Jr-Hau; Ager, Joel W.; Wu, Ming C.; Javey, Ali

2018-01-01

Transition-metal dichalcogenide monolayers have naturally terminated surfaces and can exhibit a near-unity photoluminescence quantum yield in the presence of suitable defect passivation. To date, steady-state monolayer light-emitting devices suffer from Schottky contacts or require complex heterostructures. We demonstrate a transient-mode electroluminescent device based on transition-metal dichalcogenide monolayers (MoS, WS, MoSe, and WSe) to overcome these problems. Electroluminescence from this dopant-free two-terminal device is obtained by applying an AC voltage between the gate and the semiconductor. Notably, the electroluminescence intensity is weakly dependent on the Schottky barrier height or polarity of the contact. We fabricate a monolayer seven-segment display and achieve the first transparent and bright millimeter-scale light-emitting monolayer semiconductor device.

Large-area and bright pulsed electroluminescence in monolayer semiconductors

KAUST Repository

Lien, Der-Hsien

2018-04-04

Transition-metal dichalcogenide monolayers have naturally terminated surfaces and can exhibit a near-unity photoluminescence quantum yield in the presence of suitable defect passivation. To date, steady-state monolayer light-emitting devices suffer from Schottky contacts or require complex heterostructures. We demonstrate a transient-mode electroluminescent device based on transition-metal dichalcogenide monolayers (MoS, WS, MoSe, and WSe) to overcome these problems. Electroluminescence from this dopant-free two-terminal device is obtained by applying an AC voltage between the gate and the semiconductor. Notably, the electroluminescence intensity is weakly dependent on the Schottky barrier height or polarity of the contact. We fabricate a monolayer seven-segment display and achieve the first transparent and bright millimeter-scale light-emitting monolayer semiconductor device.

A new method to detect and correct sample tilt in scanning transmission electron microscopy bright-field imaging

Energy Technology Data Exchange (ETDEWEB)

Brown, H.G. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Ishikawa, R.; Sánchez-Santolino, G. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Lugg, N.R., E-mail: shibata@sigma.t.u-tokyo.ac.jp [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Ikuhara, Y. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan); Allen, L.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Shibata, N. [Institute of Engineering Innovation, School of Engineering, University of Tokyo, Tokyo 113-8656 (Japan)

2017-02-15

Important properties of functional materials, such as ferroelectric shifts and octahedral distortions, are associated with displacements of the positions of lighter atoms in the unit cell. Annular bright-field scanning transmission electron microscopy is a good experimental method for investigating such phenomena due to its ability to image light and heavy atoms simultaneously. To map atomic positions at the required accuracy precise angular alignment of the sample with the microscope optical axis is necessary, since misalignment (tilt) of the specimen contributes to errors in position measurements of lighter elements in annular bright-field imaging. In this paper it is shown that it is possible to detect tilt with the aid of images recorded using a central bright-field detector placed within the inner radius of the annular bright-field detector. For a probe focus near the middle of the specimen the central bright-field image becomes especially sensitive to tilt and we demonstrate experimentally that misalignment can be detected with a precision of less than a milliradian, as we also confirm in simulation. Coma in the probe, an aberration that can be misidentified as tilt of the specimen, is also investigated and it is shown how the effects of coma and tilt can be differentiated. The effects of tilt may be offset to a large extent by shifting the diffraction plane detector an amount equivalent to the specimen tilt and we provide an experimental proof of principle of this using a segmented detector system. - Highlights: • Octahedral distortions are associated with displacements of lighter atoms. • Annular bright-field imaging is sensitive to light and heavy atoms simultaneously. • Mistilt of the specimen leads to errors in position measurements of lighter elements. • It is possible to detect tilt using images taken by a central bright-field detector. • Tilt may be offset by shifting the diffraction plane detector by an equivalent amount.

Development of a Highly Efficient Hybrid White Organic-Light-Emitting Diode with a Single Emission Layer by Solution Processing.

Science.gov (United States)

Wu, Jun-Yi; Chen, Show-An

2018-02-07

We use a mixed host, 2,6-bis[3-(carbazol-9-yl)phenyl]pyridine blended with 20 wt % tris(4-carbazoyl-9-ylphenyl)amine, to lower the hole-injection barrier, along with the bipolar and high-photoluminescence-quantum-yield (Φ p = 84%), blue thermally activated delay fluorescence (TADF) material of 9,9-dimethyl-9,10-dihydroacridine-2,4,6-triphenyl-1,3,5-triazine (DMAC-TRZ) as a blue dopant to compose the emission layer for the fabrication of a TADF blue organic-light-emitting diode (BOLED). The device is highly efficient with the following performance parameters: maximum brightness (B max ) = 57586 cd/m 2 , maximum current efficiency (CE max ) = 35.3 cd/A, maximum power efficiency (PE max ) = 21.4 lm/W, maximum external quantum efficiency (EQE max ) = 14.1%, and CIE coordinates (0.18, 0.42). This device has the best performance recorded among the reported solution-processed TADF BOLEDs and has a low efficiency roll-off: at brightness values of 1000 and 5000 cd/m 2 , its CEs are close, being 35.1 and 30.1 cd/A, respectively. Upon further doping of the red phosphor Ir(dpm)PQ 2 (emission peak λ max = 595 nm) into the blue emission layer, we obtained a TADF-phosphor hybrid white organic-light-emitting diode (T-P hybrid WOLED) with high performance: B max = 43594 cd/m 2 , CE max = 28.8 cd/A, PE max = 18.1 lm/W, and CIE coordinates (0.38, 0.44). This B max = 43594 cd/m 2 is better than that of the vacuum-deposited WOLED with a blue TADF emitter, 10000 cd/m 2 . This is also the first report on a T-P hybrid WOLED with a solution-processed emitting layer.

Characterization and effect of light on the plasma membrane H(+) -ATPase of bean leaves

Science.gov (United States)

Linnemeyer, P. A.; Van Volkenburgh, E.; Cleland, R. E.

1990-01-01

Proton excretion from bean (Phaseolus vulgaris L.) leaf cells is increased by bright white light. To test whether this could be due, at least in part, to an increase in plasma membrane (PM) ATPase activity, PM vesicles were isolated from primary leaves by phase partitioning and used to characterize PM ATPase activity and changes in response to light. ATPase activity was characterized as magnesium ion dependent, vanadate sensitive, and slightly stimulated by potassium chloride. The pH optimum was 6.5, the Km was approximately 0.30 millimolar ATP, and the activity was about 60% latent. PM vesicles were prepared from leaves of plants grown for 11 days in dim red light (growing slowly) or grown for 10 days in dim red light and then transferred to bright white-light for 1 day (growing rapidly). For both light treatments, ATPase specific activity was approximately 600 to 700 nanomoles per milligram protein per minute, and the latency, Km, and sensitivity to potassium chloride were also similar. PM vesicles from plants grown in complete darkness, however, exhibited a twofold greater specific activity. We conclude that the promotion of leaf growth and proton excretion by bright white light is not due to an increase in ATPase specific activity. Light does influence ATPase activity, however; both dim red light and bright white light decreased the ATPase specific activity by nearly 50% as compared with dark-grown leaves.

High Output LED-Based Profile Lighting Fixture

DEFF Research Database (Denmark)

Török, Lajos; Beczkowski, Szymon; Munk-Nielsen, Stig

2011-01-01

Recent developments in power light emitting diode (LED) industry have made LEDs suitable for being efficiently used in high intensity lighting fixtures instead of the commonly used high intensity discharge (HID) lamps. A high output LEDbased profile-light fixture is presented in this paper...

Extraocular light via the ear canal does not acutely affect human circadian physiology, alertness and psychomotor vigilance performance.

Science.gov (United States)

Bromundt, Vivien; Frey, Sylvia; Odermatt, Jonas; Cajochen, Christian

2014-04-01

We aimed at testing potential effects of extraocular bright light via the ear canals on human evening melatonin levels, sleepiness and psychomotor vigilance performance. Twenty healthy young men and women (10/10) kept a regular sleep-wake cycle during the 2-week study. The volunteers reported to the laboratory on three evenings, 2 h 15 min before usual bedtime, on average at 21:45 h. They were exposed to three different light conditions, each lasting for 12 min: extraocular bright light via the ear canal, ocular bright light as an active control condition and a control condition (extraocular light therapy device with completely blacked out LEDs). The timing of exposure was on average from 22:48 to 23:00 h. During the 2-h protocol, saliva samples were collected in 15-min intervals for melatonin assays along with subjective sleepiness ratings, and the volunteers performed a 10-min visual psychomotor vigilance task (PVT) prior to and after each light condition. The evening melatonin rise was significantly attenuated after the 12-min ocular bright light exposure while no significant changes were observed after the extraocular bright light and sham light condition. Subjective sleepiness decreased immediately over a short period only after ocular light exposure. No significant differences were observed for mean reaction times and the number of lapses for the PVT between the three light conditions. We conclude that extraocular transcranial light exposure in the late evening does not suppress melatonin, reduce subjective sleepiness or improve performance, and therefore, does not acutely influence the human circadian timing system.

Low-intensity blue-enriched white light (750 lux) and standard bright light (10,000 lux) are equally effective in treating SAD. A randomized controlled study.

Science.gov (United States)

Meesters, Ybe; Dekker, Vera; Schlangen, Luc J M; Bos, Elske H; Ruiter, Martine J

2011-01-28

Photoreceptor cells containing melanopsin play a role in the phase-shifting effects of short-wavelength light. In a previous study, we compared the standard light treatment (SLT) of SAD with treatment using short-wavelength blue-enriched white light (BLT). Both treatments used the same illuminance (10,000 lux) and were equally highly effective. It is still possible, however, that neither the newly-discovered photoreceptor cells, nor the biological clock play a major role in the therapeutic effects of light on SAD. Alternatively, these effects may at least be partly mediated by these receptor cells, which may have become saturated as a result of the high illuminances used in the therapy. This randomized controlled study compares the effects of low-intensity BLT to those of high-intensity SLT. In a 22-day design, 22 patients suffering from a major depression with a seasonal pattern (SAD) were given light treatment (10,000 lux) for two weeks on workdays. Subjects were randomly assigned to either of the two conditions, with gender and age evenly distributed over the groups. Light treatment either consisted of 30 minutes SLT (5000 °K) with the EnergyLight® (Philips, Consumer Lifestyle) with a vertical illuminance of 10,000 lux at eye position or BLT (17,000 °K) with a vertical illuminance of 750 lux using a prototype of the EnergyLight® which emitted a higher proportion of short-wavelengths. All participants completed questionnaires concerning mood, activation and sleep quality on a daily basis. Mood and energy levels were also assessed on a weekly basis by means of the SIGH-SAD and other assessment tools. On day 22, SIGH-SAD ratings were significantly lower than on day 1 (SLT 65.2% and BLT 76.4%). On the basis of all assessments no statistically significant differences were found between the two conditions. With sample size being small, conclusions can only be preliminary. Both treatment conditions were found to be highly effective. The therapeutic effects of low

Low-intensity blue-enriched white light (750 lux and standard bright light (10 000 lux are equally effective in treating SAD. A randomized controlled study

Directory of Open Access Journals (Sweden)

Bos Elske H

2011-01-01

Full Text Available Abstract Background Photoreceptor cells containing melanopsin play a role in the phase-shifting effects of short-wavelength light. In a previous study, we compared the standard light treatment (SLT of SAD with treatment using short-wavelength blue-enriched white light (BLT. Both treatments used the same illuminance (10 000 lux and were equally highly effective. It is still possible, however, that neither the newly-discovered photoreceptor cells, nor the biological clock play a major role in the therapeutic effects of light on SAD. Alternatively, these effects may at least be partly mediated by these receptor cells, which may have become saturated as a result of the high illuminances used in the therapy. This randomized controlled study compares the effects of low-intensity BLT to those of high-intensity SLT. Method In a 22-day design, 22 patients suffering from a major depression with a seasonal pattern (SAD were given light treatment (10 000 lux for two weeks on workdays. Subjects were randomly assigned to either of the two conditions, with gender and age evenly distributed over the groups. Light treatment either consisted of 30 minutes SLT (5000°K with the EnergyLight® (Philips, Consumer Lifestyle with a vertical illuminance of 10 000 lux at eye position or BLT (17 000°K with a vertical illuminance of 750 lux using a prototype of the EnergyLight® which emitted a higher proportion of short-wavelengths. All participants completed questionnaires concerning mood, activation and sleep quality on a daily basis. Mood and energy levels were also assessed on a weekly basis by means of the SIGH-SAD and other assessment tools. Results On day 22, SIGH-SAD ratings were significantly lower than on day 1 (SLT 65.2% and BLT 76.4%. On the basis of all assessments no statistically significant differences were found between the two conditions. Conclusion With sample size being small, conclusions can only be preliminary. Both treatment conditions were found

The advanced light source: America's brightest light for science and industry

International Nuclear Information System (INIS)

Cross, J.; Lawler, G.

1994-03-01

America's brightest light comes from the Advanced Light Source (ALS), a national facility for scientific research, product development, and manufacturing. Completed in 1993, the ALS produces light in the ultraviolet and x-ray regions of the spectrum. Its extreme brightness provides opportunities for scientific and technical progress not possible anywhere else. Technology is poised on the brink of a major revolution - one in which vital machine components and industrial processes will be drastically miniaturized. Industrialized nations are vying for leadership in this revolution - and the huge economic rewards the leaders will reap

A sudden brightness decrease of the young pre-MS object GM Cep

Science.gov (United States)

Munari, U.; Castellani, F.; Giannini, T.; Antoniucci, S.; Lorenzetti, D.

2017-11-01

In the framework of our EXor monitoring programme dubbed EXORCISM (EXOR OptiCal and Infrared Systematic Monitoring - Antoniucci et al. 2013 PPVI, Lorenzetti et al. 2007 ApJ 665, 1182; Lorenzetti et al. 2009 ApJ 693, 1056), we observed a new fading of the optical brightness of the Young Stellar Object (YSO) GM Cep (d=870 pc). This is a well studied variable (Semkov & Peneva 2012 APSS,338,95; Ibryamov et al. 2015 PASA,32,11; Xiao, Kroll, & Henden 2010 AJ, 139, 1527; Sicilia-Aguilar et al. 2008 ApJ,673,382-3) whose light-curve is dominated by recurrent brightness dims, interpreted as non-periodical eclipse events due to orbiting dust structures that move along the line of sight (UXor-type variability - Grinin 1988).

Influence of Two Different Light Intensities from 16:00 to 20:30 Hours on Evening Dressing Behavior in the Cold

OpenAIRE

Kim, Hee-Eun; Tokura, Hiromi

2007-01-01

The present experiment tested our hypothesis that the subjects will wear more clothing in the evening cold under the influence of bright light exposure in the late afternoon and evening. Nine young female adults participated in this study. Light intensity was controlled from 9:00 h to 16:00 h at 100 lx, and from 16:00 h to 20:30 h either at 3000 lx in the bright light (»Bright«) or at 10 lx in the dim light (»Dim«) conditions. Light intensity was maintained at 10 lx from 20:30 h to ...

Projection displays and MEMS: timely convergence for a bright future

Science.gov (United States)

Hornbeck, Larry J.

1995-09-01

Projection displays and microelectromechanical systems (MEMS) have evolved independently, occasionally crossing paths as early as the 1950s. But the commercially viable use of MEMS for projection displays has been illusive until the recent invention of Texas Instruments Digital Light Processing TM (DLP) technology. DLP technology is based on the Digital Micromirror DeviceTM (DMD) microchip, a MEMS technology that is a semiconductor digital light switch that precisely controls a light source for projection display and hardcopy applications. DLP technology provides a unique business opportunity because of the timely convergence of market needs and technology advances. The world is rapidly moving to an all- digital communications and entertainment infrastructure. In the near future, most of the technologies necessary for this infrastrucutre will be available at the right performance and price levels. This will make commercially viable an all-digital chain (capture, compression, transmission, reception decompression, hearing, and viewing). Unfortunately, the digital images received today must be translated into analog signals for viewing on today's televisions. Digital video is the final link in the all-digital infrastructure and DLP technoogy provides that link. DLP technology is an enabler for digital, high-resolution, color projection displays that have high contrast, are bright, seamless, and have the accuracy of color and grayscale that can be achieved only by digital control. This paper contains an introduction to DMD and DLP technology, including the historical context from which to view their developemnt. The architecture, projection operation, and fabrication are presented. Finally, the paper includes an update about current DMD business opportunities in projection displays and hardcopy.

Recent developments in the application of rf superconductivity to high-brightness and high-gradient ion beam accelerators

International Nuclear Information System (INIS)

Delayen, J.R.; Bohn, C.L.; Kennedy, W.L.; Nichols, G.L.; Roche, C.T.; Sagalovsky, L.

1991-01-01

A development program is underway to apply rf superconductivity to the design of continuous-wave (cw) linear accelerators for high- brightness ion beams. Since the last workshop, considerable progress has been made both experimentally and theoretically toward this application. Recent tests of niobium resonators for ion acceleration have yielded average accelerating gradients as high as 18 MV/m. In an experiment with a radio-frequency quadrupole geometry, niobium was found to sustain cw peak surface electric fields as high as 128 MV/m over large (10 cm 2 ) surface areas. Theoretical studies of beam impingement and cumulative beam breakup have also yielded encouraging results. Consequently, a section of superconducting resonators and focusing elements has been designed for tests with high-current deuteron beams. In addition, considerable data pertaining to the rf properties of high-T c superconductors has been collected at rf-field amplitudes and frequencies of interest in connection with accelerator operation. This paper summarizes the recent progress and identifies current and future work in the areas of accelerator technology and superconducting materials which will build upon it

Light Pollution: Outdoor lighting is a growing threat to astronomy.

Science.gov (United States)

Riegel, K W

1973-03-30

There have been major qualitative and quantitative changes in outdoor lighting technology in the last decade. The level of skylight caused by outdoor lighting systems is growing at a very high rate, about 20 percent per year nationwide. In addition, the spectral distribution of man-made light pollution may change in the next decade from one containing a few mercury lines to one containing dozens of lines and a significantly increased continuum level. Light pollution is presently damaging to some astronomical programs, and it is likely to become a major factor limiting progress in the next decade. Suitable sites in the United States for new dark sky observing facilities are very difficult to find. Some of the increase in outdoor illumination is due to the character of national growth and development. Some is due to promotional campaigns, in which questionable arguments involving public safety are presented. There are protective measures which might be adopted by the government; these would significantly aid observational astronomy, without compromising the legitimate outdoor lighting needs of society. Observatories should establish programs to routinely monitor sky brightness as a function of position, wavelength, and time. The astronomical community should establish a mechanism by which such programs can be supported and coordinated.

Untangling the contributions of image charge and laser profile for optimal photoemission of high-brightness electron beams

International Nuclear Information System (INIS)

Portman, J.; Zhang, H.; Makino, K.; Ruan, C. Y.; Berz, M.; Duxbury, P. M.

2014-01-01

Using our model for the simulation of photoemission of high brightness electron beams, we investigate the virtual cathode physics and the limits to spatio-temporal and spectroscopic resolution originating from the image charge on the surface and from the profile of the exciting laser pulse. By contrasting the effect of varying surface properties (leading to expanding or pinned image charge), laser profiles (Gaussian, uniform, and elliptical), and aspect ratios (pancake- and cigar-like) under different extraction field strengths and numbers of generated electrons, we quantify the effect of these experimental parameters on macroscopic pulse properties such as emittance, brightness (4D and 6D), coherence length, and energy spread. Based on our results, we outline optimal conditions of pulse generation for ultrafast electron microscope systems that take into account constraints on the number of generated electrons and on the required time resolution.

Proxy magnetometry of the photosphere: why are G-band bright points so bright?

NARCIS (Netherlands)

Rutten, R.J.; Kiselman, Dan; Voort, Luc Rouppe van der; Plez, Bertrand

2000-01-01

We discuss the formation of G-band bright points in terms of standard uxtube modeling, in particular the 1D LTE models constructed by Solanki and coworkers. Combined with LTE spectral synthesis they explain observed G-band bright point contrasts quite well. The G-band contrast increase over the

Beam brightness calculation for analytical and empirical distribution functions

International Nuclear Information System (INIS)

Myers, T.J.; Boulais, K.A.; O, Y.S.; Rhee, M.J.

1992-01-01

The beam brightness, a figure of merit for a beam quality useful for high-current low-emittance beams, was introduced by van Steenbergen as B = I/V 4 , where I is the beam current and V 4 is the hypervolume in the four-dimensional trace space occupied by the beam particles. Customarily, the brightness is expressed in terms of the product of emittances ε x ε y as B = ηI/(π 2 ε x ε y ), where η is a form factor of order unity which depends on the precise definition of emittance and hypervolume. Recently, a refined definition of the beam brightness based on the arithmetic mean value defined in statistics is proposed. The beam brightness is defined as B triple-bond 4 > = I -1 ∫ ρ 4 2 dxdydx'dy', where I is the beam current given by I ∫ ρ 4 dxdydx'dy'. Note that in this definition, neither the hypervolume V 4 nor the emittance, are explicitly used; the brightness is determined solely by the distribution function. Brightnesses are unambiguously calculated and expressed analytically in terms of the respective beam current and effective emittance for a few commonly used distribution functions, including Maxwellian and water-bag distributions. Other distributions of arbitrary shape frequently encountered in actual experiments are treated numerically. The resulting brightnesses are expressed in the form B = ηI/(π 2 ε x ε y ), and η is found to be weakly dependent on the form of velocity distribution as well as spatial distribution

Design of a Multi-Color Lamp Using High Brightness RGB LEDs

Energy Technology Data Exchange (ETDEWEB)

Song, S.B.; Kang, S.H.; Yeo, I.S. [Chonnam National University, Kwangju (Korea)

2003-02-01

This paper proposes the design of a multi-color lamp using high brightness RGB LEDs for color variation. Appropriate number of RGB LEDs is so chosen according to the color mixing theory that the overall LEDs represent a color temperature of 6500K. Also, the chosen RGB LEDs are suitably arranged by using an optical design program. The lamp has an internal controller circuit, so it can be directly connected to the existing incandescent lamp socket. It's main body is comprised of two PCB layers. The upper layer contains 44 LEDs and the lower one has a simple microcontroller-based PWM control circuit. The lamp has functions of both ON/OFF control and PWM control, and enables color variation of over 100,000 colors and of more than 10 patterns. (author). 7 refs., 11 figs., 3 tabs.

RADIOASTRON OBSERVATIONS OF THE QUASAR 3C273: A CHALLENGE TO THE BRIGHTNESS TEMPERATURE LIMIT

Energy Technology Data Exchange (ETDEWEB)

Kovalev, Y. Y.; Kardashev, N. S.; Voitsik, P. A.; Kovalev, Yu. A.; Lisakov, M. M.; Sokolovsky, K. V. [Astro Space Center of Lebedev Physical Institute, Profsoyuznaya 84/32, 117997 Moscow (Russian Federation); Kellermann, K. I. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Lobanov, A. P.; Zensus, J. A.; Anderson, J. M.; Bach, U.; Kraus, A. [Max-Planck-Institute for Radio Astronomy, Auf dem Hügel 69, D-53121 (Germany); Johnson, M. D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gurvits, L. I. [Joint Institute for VLBI ERIC, P.O. Box 2, 7990 AA Dwingeloo (Netherlands); Jauncey, D. L. [CSIRO Astronomy and Space Sciences, Epping, NSW 1710 (Australia); Ghigo, F. [National Radio Astronomy Observatory, Rt. 28/92, Green Bank, WV 24944-0002 (United States); Ghosh, T.; Salter, C. J. [Arecibo Observatory, NAIC, HC3 Box 53995, Arecibo, Puerto Rico, PR 00612 (United States); Petrov, L. Yu. [Astrogeo Center, 7312 Sportsman Drive, Falls Church, VA 22043 (United States); Romney, J. D. [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801-0387 (United States)

2016-03-20

Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of 10{sup 11.5} K. Relativistic boosting can increase its observed value, but apparent brightness temperatures much in excess of 10{sup 13} K are inaccessible using ground-based very long baseline interferometry (VLBI) at any wavelength. We present observations of the quasar 3C 273, made with the space VLBI mission RadioAstron on baselines up to 171,000 km, which directly reveal the presence of angular structure as small as 26 μas (2.7 light months) and brightness temperature in excess of 10{sup 13} K. These measurements challenge our understanding of the non-thermal continuum emission in the vicinity of supermassive black holes and require a much higher Doppler factor than what is determined from jet apparent kinematics.

The Extremely Luminous Quasar Survey (ELQS) in SDSS and the high-z bright-end Quasar Luminosity Function

Science.gov (United States)

Schindler, Jan-Torge; Fan, Xiaohui; McGreer, Ian

2018-01-01

Studies of the most luminous quasars at high redshift directly probe the evolution of the most massive black holes in the early Universe and their connection to massive galaxy formation. Unfortunately, extremely luminous quasars at high redshift are very rare objects. Only wide area surveys have a chance to constrain their population. The Sloan Digital Sky Survey (SDSS) nd the Baryon Oscillation Spectroscopic Survey (BOSS) have so far provided the most widely adopted measurements of the type I quasar luminosity function (QLF) at z>3. However, a careful re-examination of the SDSS quasar sample revealed that the SDSS quasar selection is in fact missing a significant fraction of $z~3$ quasars at the brightest end.We have identified the purely optical color selection of SDSS, where quasars at these redshifts are strongly contaminated by late-type dwarfs, and the spectroscopic incompleteness of the SDSS footprint as the main reasons. Therefore we have designed the Extremely Luminous Quasar Survey (ELQS), based on a novel near-infrared JKW2 color cut using WISE AllWISE and 2MASS all-sky photometry, to yield high completeness for very bright (i < 18.0) quasars in the redshift range of 2.8<= z<=5.0. It effectively uses Random Forest machine-learning algorithms on SDSS and WISE photometry for quasar-star classification and photometric redshift estimation.The ELQS is spectroscopically following up ~230 new quasar candidates in an area of ~12000 deg2 in the SDSS footprint, to obtain a well-defined and complete quasar sample for an accurate measurement of the bright-end quasar luminosity function (QLF) at 2.8<= z<=5.0. So far the ELQS has identified 75 bright new quasars in this redshift range and observations of the fall sky will continue until the end of the year. At the AAS winter meeting we will present the full spectroscopic results of the survey, including a re-estimation and extension of the high-z QLF toward higher luminosities.

Environmentally Benign Technology for Efficient Warm-White Light Emission

Science.gov (United States)

Shen, Pin-Chun; Lin, Ming-Shiun; Lin, Ching-Fuh

2014-06-01

Nowadays efficient down conversion for white light emission is mainly based on rare-earth doped phosphors or cadmium-containing quantum dots. Although they exhibit high luminescence efficiency, the rare-earth mining and cadmium pollution have so far led to extremely high environmental cost, which conflicts the original purpose of pursuing efficient lighting. Here, we explore a new strategy to achieve efficient luminescence conversion based on polymer-decorated nanoparticles. The ZnO and Mn2+ doped ZnS nanoparticles are encapsulated by poly(9,9-di-n- hexylfluorenyl-2,7-diyl). The resultant core-shell nanocomposites then encompass three UV-to-visible luminescence conversion routes for photon emissions at blue, green, and orange colors, respectively. As a result, the color temperature is widely tunable (2100 K ~ 6000 K), so candle light or pure white light can be generated. The quantum yield up to 91% could also be achieved. Such rare-earth-element free nanocomposites give the bright perspectives for energy-saving, healthy, and environmentally benign lighting.

Limits of colour vision in dim light.

Science.gov (United States)

Kelber, Almut; Lind, Olle

2010-09-01

Humans and most vertebrates have duplex retinae with multiple cone types for colour vision in bright light, and one single rod type for achromatic vision in dim light. Instead of comparing signals from multiple spectral types of photoreceptors, such species use one highly sensitive receptor type thus improving the signal-to-noise ratio at night. However, the nocturnal hawkmoth Deilephila elpenor, the nocturnal bee Xylocopa tranquebarica and the nocturnal gecko Tarentola chazaliae can discriminate colours at extremely dim light intensities. To be able to do so, they sacrifice spatial and temporal resolution in favour of colour vision. We review what is known about colour vision in dim light, and compare colour vision thresholds with the optical sensitivity of the photoreceptors in selected animal species with lens and compound eyes. © 2010 The Authors, Ophthalmic and Physiological Optics © 2010 The College of Optometrists.

Drop-out and mood improvement: a randomised controlled trial with light exposure and physical exercise [ISRCTN36478292

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Lönnqvist Jouko

2004-08-01

Full Text Available Abstract Background Combining bright light exposure and physical exercise may be an effective way of relieving depressive symptoms. However, relatively little is known about individual factors predicting either a good response or treatment failure. We explored background variables possibly explaining the individual variation in treatment response or failure in a randomised trial. Methods Participants were volunteers of working-age, free from prior mental disorders and recruited via occupational health centres. The intervention was a randomised 8-week trial with three groups: aerobics in bright light, aerobics in normal room lighting, and relaxation/stretching in bright light. Good response was defined as a 50% decrease in the symptom score on either the Hamilton Depression Rating Scale (HDRS or 8-item scale of atypical symptoms. Background variables for the analysis included sex, age, body-mass index, general health habits, seasonal pattern, and sleep disturbances. Results Complete data were received from 98 subjects (11 men, 87 women. Of them, 42 (5 men, 37 women were classified as responders on the HDRS. Overall, light had a significant effect on the number of responders, as assessed with the HDRS (X2 = .02. The number needed to treat (NNT for light was 3.8. Conclusions We investigated the effect of bright light and exercise on depressive symptoms. Problems with sleep, especially initial insomnia, may predict a good response to treatment using combined light and exercise. Bright light exposure and physical exercise, even in combination, seem to be well tolerated and effective on depressive symptoms.

Improvement of white organic light emitting diode performances by an annealing process

Energy Technology Data Exchange (ETDEWEB)

Sepeai, Suhaila, E-mail: suhaila_sepeai@yahoo.co [Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor (Malaysia); Salleh, Muhamad Mat, E-mail: mms@pkrisc.cc.ukm.m [Institute Of Microengineering And Nanoelectronic, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor (Malaysia); Yahaya, Muhammad; Umar, Akrajas Ali [Institute Of Microengineering And Nanoelectronic, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor (Malaysia)

2009-06-30

White organic light emitting diode (OLED) devices with the structure ITO/PHF:rubrene/Al, in which PHF (poly(9,9-di-n-hexylfluorenyl-2,7-diyl)) is used as blue light emitting host and rubrene (5,6,11,12-tetraphenylnapthacene) as an orange dye dopant, have been fabricated. Indium tin oxide (ITO) coated-glass and aluminium were used as anode and cathode, respectively. The devices were fabricated with various rubrene-dopant to obtain a white light emission. The OLED device that composed of several concentrations of rubrene-doped PHF film was prepared in this study. It was found that the concentration of rubrene in the PHF-rubrene thin film matrix plays a key role in producing the white color emission. In a typical result, the device composed of 0.06 wt.% rubrene-dopant produced the white light emission with the Commission Internationale de L'Eclairage (CIE) coordinate of (0.30,0.33). The turn-on voltage and the brightness were found to be as low as 14.0 V and as high as 6540 cd/m{sup 2}, respectively. The annealing technique at relatively low temperature (50 {sup o}C, 100 {sup o}C, and 150 {sup o}C) was then used to optimize the performance of the device. In a typical result, the turn-on voltage of the device could be successfully reduced and the brightness could be increased using the annealing technique. At an optimum condition, for example, annealed at 150 {sup o}C, the turn-on voltage as low as 8.0 V and the brightness as high as 9040 cd/m{sup 2} were obtained. The mechanism for the improvement of the device performance upon annealing will be discussed.

High-performance flexible inverted organic light-emitting diodes by exploiting MoS2 nanopillar arrays as electron-injecting and light-coupling layers.

Science.gov (United States)

Guo, Kunping; Si, Changfeng; Han, Ceng; Pan, Saihu; Chen, Guo; Zheng, Yanqiong; Zhu, Wenqing; Zhang, Jianhua; Sun, Chang; Wei, Bin

2017-10-05

Inverted organic light-emitting diodes (IOLEDs) on plastic substrates have great potential application in flexible active-matrix displays. High energy consumption, instability and poor electron injection are key issues limiting the commercialization of flexible IOLEDs. Here, we have systematically investigated the electrooptical properties of molybdenum disulfide (MoS 2 ) and applied it in developing highly efficient and stable blue fluorescent IOLEDs. We have demonstrated that MoS 2 -based IOLEDs can significantly improve electron-injecting capacity. For the MoS 2 -based device on plastic substrates, we have achieved a very high external quantum efficiency of 7.3% at the luminance of 9141 cd m -2 , which is the highest among the flexible blue fluorescent IOLEDs reported. Also, an approximately 1.8-fold improvement in power efficiency was obtained compared to glass-based IOLEDs. We attributed the enhanced performance of flexible IOLEDs to MoS 2 nanopillar arrays due to their light extraction effect. The van der Waals force played an important role in the formation of MoS 2 nanopillar arrays by thermal evaporation. Notably, MoS 2 -based flexible IOLEDs exhibit an intriguing efficiency roll-up, that is, the current efficiency increases slightly from 14.0 to 14.6 cd A -1 with the luminance increasing from 100 to 5000 cd m -2 . In addition, we observed that the initial brightness of 500 cd m -2 can be maintained at 97% after bending for 500 cycles, demonstrating the excellent mechanical stability of flexible IOLEDs. Furthermore, we have successfully fabricated a transparent, flexible IOLED with low efficiency roll-off at high current density.

Ho-doped SrBi{sub 2}Nb{sub 2}O{sub 9} multifunctional ceramics with bright green emission and good electrical properties

Energy Technology Data Exchange (ETDEWEB)

Yu, Lei; Hao, Jigong; Li, Wei [College of Materials Science and Engineering, Liaocheng University, Liaocheng (China); Xu, Zhijun; Chu, Ruiqing [School of Environmental and Materials Engineering, Yantai University, Yantai (China)

2017-10-15

Ho{sup 3+}-doped SrBi{sub 2}Nb{sub 2}O{sub 9} multifunctional ferroelectric ceramics with bright green light emission and good electrical properties were fabricated in this work. Under blue light excitation, samples showed bright green light with two typical emission bands: a strong green emission centered at 545 nm corresponding to the intra f-f transition from the excited {sup 5}S{sub 2} to the ground state {sup 5}I{sub 8} and a relatively weak red emission located 653 nm induced by the {sup 5}F{sub 5} → {sup 5}I{sub 8} transition of Ho{sup 3+}. Due to the concentration quenching effect, the intensity of emission was strongly dependent on the doping concentration. Furthermore, the electrical properties have improved by Ho{sup 3+} doping. At x = 0.004, samples exhibit optimal electrical properties with high Curie temperature (T{sub c} = 441 C) and large 2P{sub r} and d{sub 33} values (2P{sub r} = 15.54 μC cm{sup -2}, d{sub 33} = 19 pC/N). These results demonstrate that the SBN-xHo ceramics possess excellent multifunctional properties to achieve a variety of applications. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Completion of the brightness upgrade of the ALS

International Nuclear Information System (INIS)

Steier, C; Madur, A; Bailey, B; Berg, K; Biocca, A; Black, A; Casey, P; Colomb, D; Gunion, B; Li, N; Marks, S; Nishimura, H; Pappas, C; Petermann, K; Portmann, G; Prestemon, S; Rawlins, A; Robin, D; Rossi, S; Scarvie, T

2014-01-01

The Advanced Light Source (ALS) at Berkeley Lab remains one of the brightest sources for soft x-rays worldwide. A multiyear upgrade of the ALS is underway, which includes new and replacement x-ray beamlines, a replacement of many of the original insertion devices and many upgrades to the accelerator. The accelerator upgrade that affects the ALS performance most directly is the ALS brightness upgrade [1], which reduces the horizontal emittance from 6.3 to 2.0 nm (2.5 nm effective). Magnets for this upgrade were installed in late 2012 and early 2013 followed by user operation with the reduced emittance.

Bright light therapy as part of a multicomponent management program improves sleep and functional outcomes in delirious older hospitalized adults

Directory of Open Access Journals (Sweden)

Chong MS

2013-05-01

Full Text Available Mei Sian Chong,1 Keng Teng Tan,2 Laura Tay,1 Yoke Moi Wong,1 Sonia Ancoli-Israel3,41Department of Geriatric Medicine, Tan Tock Seng Hospital, Singapore; 2Department of Pharmacy, Tan Tock Seng Hospital, Singapore; 3Departments of Psychiatry and Medicine, University of California, San Diego, CA, USA; 4VA Center of Excellence for Stress and Mental Health (CESAMH, San Diego, CA, USAObjective: Delirium is associated with poor outcomes following acute hospitalization. A specialized delirium management unit, the Geriatric Monitoring Unit (GMU, was established. Evening bright light therapy (2000–3000 lux; 6–10 pm daily was added as adjunctive treatment, to consolidate circadian activity rhythms and improve sleep. This study examined whether the GMU program improved sleep, cognitive, and functional outcomes in delirious patients.Method: A total of 228 patients (mean age = 84.2 years were studied. The clinical characteristics, delirium duration, delirium subtype, Delirium Rating Score (DRS, cognitive status (Chinese Mini–Mental State Examination, functional status (modified Barthel Index [MBI], and chemical restraint use during the initial and predischarge phase of the patient’s GMU admission were obtained. Nurses completed hourly 24-hour patient sleep logs, and from these, the mean total sleep time, number of awakenings, and sleep bouts (SB were computed.Results: The mean delirium duration was 6.7 ± 4.6 days. Analysis of the delirium subtypes showed that 18.4% had hypoactive delirium, 30.2% mixed delirium, and 51.3% had hyperactive delirium. There were significant improvements in MBI scores, especially for the hyperactive and mixed delirium subtypes (P < 0.05. Significant improvements were noted on the DRS sleep–wake disturbance subscore, for all delirium-subtypes. The mean total sleep time (7.7 from 6.4 hours (P < 0.05 and length of first SB (6.0 compared with 5.3 hours (P < 0.05 improved, with decreased mean number of SBs and awakenings. The

High-intensity light-ion beam research at NRL

International Nuclear Information System (INIS)

Cooperstein, G.; Colombant, D.G.; Barker, R.J.

1982-01-01

High-brightness proton beams (.4 MA, 1 MV) have recently been extracted from 20 cm 2 axial pinch-reflex diodes (PRDs) mounted on the NRL Gamble II generator. A source power brightness of GT 10 TW/cm 2 rad 2 was achieved in these experiments. A new barrel-shaped equitorial PRD that can be coupled to PBFA-II has also been operated on Gamble II and has demonstrated 50% proton efficiency with predominately azimuthally-symmetric charged-particle flow. In other experiments the stopping power of deuterons in hot plasmas was measured using a PRD on Gamble II. Results show about 40% enhancement in stopping power over that in cold targets when the beam was focused to about .25 MA/cm 2 . Research is also being performed on transporting ion beams in large-diameter channels (>= 2.5 cm) and on a post-transport, plasma-filled, magnetic-focusing section to bring the beam to pellet dimensions. (author)

Light pollution offshore: Zenithal sky glow measurements in the mediterranean coastal waters

Science.gov (United States)

Ges, Xavier; Bará, Salvador; García-Gil, Manuel; Zamorano, Jaime; Ribas, Salvador J.; Masana, Eduard

2018-05-01

Light pollution is a worldwide phenomenon whose consequences for the natural environment and the human health are being intensively studied nowadays. Most published studies address issues related to light pollution inland. Coastal waters, however, are spaces of high environmental interest, due to their biodiversity richness and their economical significance. The elevated population density in coastal regions is accompanied by correspondingly large emissions of artificial light at night, whose role as an environmental stressor is increasingly being recognized. Characterizing the light pollution levels in coastal waters is a necessary step for protecting these areas. At the same time, the marine surface environment provides a stage free from obstacles for measuring the dependence of the skyglow on the distance to the light polluting sources, and validating (or rejecting) atmospheric light propagation models. In this work we present a proof-of-concept of a gimbal measurement system that can be used for zenithal skyglow measurements on board both small boats and large vessels under actual navigation conditions. We report the results obtained in the summer of 2016 along two measurement routes in the Mediterranean waters offshore Barcelona, travelling 9 and 31.7 km away from the coast. The atmospheric conditions in both routes were different from the ones assumed for the calculation of recently published models of the anthropogenic sky brightness. They were closer in the first route, whose results approach better the theoretical predictions. The results obtained in the second route, conducted under a clearer atmosphere, showed systematic differences that can be traced back to two expected phenomena, which are a consequence of the smaller aerosol content: the reduction of the anthropogenic sky glow at short distances from the sources, and the slower decay rate of brightness with distance, which gives rise to a relative excess of brightness at large distances from the

Light and Light Sources High-Intensity Discharge Lamps

CERN Document Server

Flesch, Peter G

2006-01-01

Light and Light Sources gives an introduction to the working principles of high-intensity discharge (HID) lamps and points out challenges and problems associated with the development and operation of HID lamps. The state-of-the-art in electrode and plasma diagnostics as well as numerical methods used for the understanding of HID lamps are described. This volume addresses students as well as scientists and researchers at universities and in industry.

From dark to bright: novel daylighting applications in solid state lighting

Science.gov (United States)

Adler, Helmar G.

2011-10-01

The term "daylighting" is used in various ways, on one hand in a more architectural sense, i.e. using existing daylight to illuminate spaces, and on the other, more recently, for using light sources to replicate daylight. The emergence of solid state lighting (SSL) opens up a large number of new avenues for daylighting. SSL allows innovative controllability of intensity and color for artificial light sources that can be advantageously applied to daylighting. With the assistance of these new technologies the combination of natural and artificial lighting could lead to improvements in energy savings and comfort of living beings. Thus it is imperative to revisit or even improve daylighting research so that building networks of the future with their sensor, energy (e.g. HVAC) and lighting requirements can benefit from the emerging capabilities. This paper will briefly review existing daylighting concepts and technology and discuss new ideas. An example of a tunable multi-color SSL system will be shown.

Bright light treatment in elderly patients with nonseasonal major depressive disorder: a randomized placebo-controlled trial.

Science.gov (United States)

Lieverse, Ritsaert; Van Someren, Eus J W; Nielen, Marjan M A; Uitdehaag, Bernard M J; Smit, Jan H; Hoogendijk, Witte J G

2011-01-01

Major depressive disorder (MDD) in elderly individuals is prevalent and debilitating. It is accompanied by circadian rhythm disturbances associated with impaired functioning of the suprachiasmatic nucleus, the biological clock of the brain. Circadian rhythm disturbances are common in the elderly. Suprachiasmatic nucleus stimulation using bright light treatment (BLT) may, therefore, improve mood, sleep, and hormonal rhythms in elderly patients with MDD. To determine the efficacy of BLT in elderly patients with MDD. Double-blind, placebo-controlled randomized clinical trial. Home-based treatment in patients recruited from outpatient clinics and from case-finding using general practitioners' offices in the Amsterdam region. Eighty-nine outpatients 60 years or older who had MDD underwent assessment at baseline (T0), after 3 weeks of treatment (T1), and 3 weeks after the end of treatment (T2). Intervention Three weeks of 1-hour early-morning BLT (pale blue, approximately 7500 lux) vs placebo (dim red light, approximately 50 lux). Mean improvement in Hamilton Scale for Depression scores at T1 and T2 using parameters of sleep and cortisol and melatonin levels. Intention-to-treat analysis showed Hamilton Scale for Depression scores to improve with BLT more than placebo from T0 to T1 (7%; 95% confidence interval, 4%-23%; P = .03) and from T0 to T2 (21%; 7%-31%; P = .001). At T1 relative to T0, get-up time after final awakening in the BLT group advanced by 7% (P hour urinary free cortisol level was 37% lower (P = .003) compared with the placebo group. The evening salivary cortisol level had decreased by 34% in the BLT group compared with an increase of 7% in the placebo group (P = .02). In elderly patients with MDD, BLT improved mood, enhanced sleep efficiency, and increased the upslope melatonin level gradient. In addition, BLT produced continuing improvement in mood and an attenuation of cortisol hyperexcretion after discontinuation of treatment. clinicaltrials